X-ray lithographic conditions for high aspect ratio SU-8 resist structures are characterized for potential application in x-ray optics and bioMEMS. The effects of the main process parameters such as exposure dose, post exposure bake, development time and the packing density of the microfabricated features on the development depth and increase in feature size at the top portion of the resist (as compared to that in mask) were investigated. As test samples, we fabricated 1mm high, densely-packed SU-8 structures comprising of 30μm square pillars with spacings of 36μm, 12μm and 6μm. Dissolution rates are found to be longer for densely packed structures than predicted by simple physical models based on isolated structures. We examine the effect on dissolution rates of the density of features in our structures. We also optimised our process with respect to the parameters described above using the Taguchi method. We find that optimisation of the development time with exposure dose and post-exposure bake time can reduce the dimensional error to ~ 3% for certain densely-packed structures.

A WC-SiC nanocomposite thin layer structure consisting of nano-grains of WC embedded in SiC has been fabricated on an n-type Si substrate by ion beam synthesis (IBS) using a metal vapor vacuum arc ion source. A SiC layer was first formed by high dose carbon implantation into the silicon substrate. Subsequent W implantation was preformed to form the WC-SiC nanocomposite structure that can be achieved under appropriate implantation and annealing conditions. Characterization of the implanted samples was performed using atomic force microscopy (AFM), conducting AFM, x-ray photoelectron spectroscopy, and transmission electron microscopy. Excellent field emission properties with an ultra-low turn-on field of 0.35 V/μm from such a nanocomposites structure have been achieved. While it has been demonstrated that the surface morphology effect and the local electrical inhomogeneity are two field enhancement mechanisms for IBS SiC/Si structures, they are not sufficient to account for the excellent emission properties of these WC-SiC nanocomposite layers. To explain the excellent field emission properties from these structures, a proximity field enhancement effect between closely spaced conducting grains in a dielectric medium and an internal quantum tunneling mechanism are proposed.

Ultra Shallow Junctions are required to successfully improve device performance with scaling to have a better threshold voltage control, improve transistor performance, reduce CHC (Channel Hot Carrier) degradation and reduce parasitic capacitance. All these play an increasingly critical role as we move on to the 45 nm node and beyond to provide the required ac and dc device performance for CMOS devices. In the low energy implant regime, four point probe based sheet resistivity measurement becomes highly unreliable as does silicon damage based metrology systems used currently for advanced process control and monitoring. A non-contact metrology method is investigated based on leakage and tunneling currents in a non-conductive film that contains the implanted dose. These shallow implants damage the non-conductive film causing leakage paths to the silicon substrate. The implant damage is proportional to the dose and energy of the implanted species. Furthermore implanting the non-conductive film causes the top layers of the film to become conductive thus changing the electrical oxide thickness of this film. Excellent correlation was found among the implanted dose, energy to the equivalent oxide thickness. Results from controlled experiments indicate that this method has potential for use in low energy implanter qualification and ultra large scale integration process control and monitoring.

Femtosecond laser pulses with energy of 0.9 nJ per pulse and a 80 MHz repetition rate at a wavelength of 750 nm were used to fabricate straight microchannels in a PMMA substrate. The size and shape of the microchannels can be controlled by changing the fabrication parameters of speed, the number of fabrication repeats and delay in-between fabrication repeats. It has been proposed that the absorption of energy in the focal region modifies the density of the polymer matrix, which after annealing the sample above the glass transition temperature results in the formation of the microchannels. Diffusion of heat through the substrate is a uniform process which has the effect of creating symmetrically shaped channels. This fabrication method is expected to have applications in the fabrication of microstructures or microfluidic devices in polymer substrates.

Wafer-to-wafer bonding techniques, such as anodic bonding or high temperature silicon direct fusion bonding, have been in development since the late 1960's and became key technologies for MEMS manufacturing. Plasma assisted wafer bonding is an emerging method offering several advantages over traditional bonding techniques. This technology was first discovered and patented in the early 1990's and has been used in SOI production for the past five years. Now plasma activation benefits are being used to enable 3D integration and advanced MEMS device fabrication and packaging. The main advantage of plasma assisted bonding is that high strength direct bonds between substrates, like Si, glass or polymers, can be achieved already below 300°C.

We present a review of our work on the development and applications of AlInGaN-based deep ultraviolet light emitting diodes (LEDs) with peak emission in the spectral range from 247 nm to 365 nm. The devices demonstrate wall-plug efficiency in excess of 2%, modulation frequency in excess of 200 MHz and very low noise performance. Single wavelength device as well as multi-wavelength high power ultraviolet lamps have been developed for applications in sterilization industry, UV-curing, optical sensors, medical, biomedical and spectroscopic instrumentation.

Scattering from metal nanoparticles via excitation of surface plasmon (SP) resonances has the potential to dramatically increase the emission of light-emitting devices. A further redshift in the plasmon resonance is possible by overcoating the metal nanoparticles with a high refractive index medium. In this paper we report a red shift in the emission enhancement peak from Silicon on Insulator (SOI) light emitting diodes (LEDs) by overcoating the metal particles with ZnS, as determined by the electroluminescence (EL) spectra. We demonstrate a 7 fold increase in the electroluminescence at 970nm with an evident redshift from 900nm for the uncoated case.

Localized surface plasmons on metallic nanoparticles can be surprisingly efficient at coupling light into or out of a silicon waveguide. We have previously reported a factor of 7 times enhancement in the electroluminescence from a silicon-on-insulator light-emitting diode with silver nanoparticles at a wavelength of 930nm. In this paper we model the scattering enhancement for metal particles on a silicon-on-insulator substrate and show that the shape of the spectrum is well predicted using the scattering cross-section and angular dependence of emission of an ideal dipole on a layered substrate. This indicates that the scattering and absorption enhancement at long wavelengths is mainly a single-particle effect, in contrast to previous suggestions that it is a waveguide-mediated multi-particle effect. In particular we show that the particle-waveguide interaction leads to a dramatic enhancement of scattered light at long wavelengths compared with the light scattered by metal islands on glass.

Fabrication of microlens array using polymer reflow is beginning to be a mainstream process, whether the polymer is directly used or whether the spherical profile is transferred by plasma etching to a glass substrate as, for example, in some handphone cameras. The focus so far has been on uniformity and obtaining lenses with equal radius and equal focal length. Actually it is easy to show using a phenomenological model that the focal length is depending on the lens radius, and not much on the contact angle, an effect that can be traced to the line tension force. For a biomedical application we need to terminate a 600um diameter imaging fiber with a group of lenses of different diameters - but with similar focal length. We have devised a microfabrication process on a silicon wafer to produce the lens with variable diameter and identical focal length, while etching the silicon wafer has helped us producing a sheath to insert the optical fiber and mount the lenses on the optical fiber.

This paper presents a characterization of wet etching of glass in HF-based solutions with a focus on etching rate, masking layers and quality of the generated surface. The first important factor that affects the deep wet etching process is the glass composition. The presence of oxides such as CaO, MgO or Al₂O₃ that give insoluble products after reaction with HF can generate rough surface and modify the etching rate. A second factor that influences especially the etch rate is the annealing process (560°C / 6 hours in N₂ environment). For annealed glass samples an increase of the etch rate with 50-60% was achieved. Another important factor is the concentration of the HF solution. For deep wet etching of Pyrex glass in hydrofluoric acid solution, different masking layers such as Cr/Au, PECVD amorphous silicon, LPCVD polysilicon and silicon carbide are analyzed. Detailed studies show that the stress in the masking layer is a critical factor for deep wet etching of glass. A low value of compressive stress is recommended. High value of tensile stress in the masking layer (200-300 MPa) can be an important factor in the generation of the pinholes. Another factor is the surface hydrophilicity. A hydrophobic surface of the masking layer will prevent the etching solution from flowing through the deposition defects (micro/nano channels or cracks) and the generation of pinholes is reduced. The stress gradient in the masking layer can also be an important factor in generation of the notching defects on the edges. Using these considerations a special multilayer masks Cr/Au/Photoresist (AZ7220) and amorphous silicon/silicon carbide/Photoresist were fabricated for deep wet etching of a 500 μm and 1mm-thick respectively Pyrex glass wafers. In both cases the etching was performed through wafer. From our knowledge these are the best results reported in the literature. The quality of the generated surface is another important factor in the fabrication process. We notice that the roughness of generated surface can be significantly improved by adding HCl in HF solution (the optimal ratio between HF (49%) and HCl (37%) was 10/1).

We present a simple yet efficient technique to obtain membrane with precise thickness by the etching of silicon in anisotropic etchant. This technique uses a mechanical holder to protect the front side of the wafer and a light signal to monitor from a distance the thickness of a reference hole in the etched wafer. The original feature in our set-up is that we measure the absorption of the light in two different bands of wavelength, one where the silicon is highly absorbant and the other where it is not, to improve the robustness of the measurement. This principle allows for effectively compensating for the fluctuation in the light source intensity, and provide real-time information on the membrane thickness, removing the incertitude inherent in the usual timed etch. We present the application of this technique to the manufacturing of thick single-crystal stiffener used to prevent the warp of stacked thin films presenting a gradient of stress.

The backward scattering of TM-polarized light by a two-side-open subwavelength slit in a metal film is analyzed. We show that the reflection coefficient versus wavelength possesses a Fabry-Perot-like dependence that is similar to the anomalous behavior of transmission reported in the study [Y. Takakura, Phys. Rev. Lett. 86, 5601 (2001)]. The open slit totally reflects the light at the near-to-resonance wavelengths. In addition, we show that the interference of incident and resonantly backward-scattered light produces in the near-field diffraction zone a spatially localized wave whose intensity is 10-10³ times greater than the incident wave, but one order of magnitude smaller than the intra-cavity intensity. The amplitude and phase of the resonant wave at the slit entrance and exit are different from that of a Fabry-Perot cavity.

DNA polymer gel was prepared by combining DNA-lipid and polymer gel. A hemicyanine dye, trans-4-{4- (dibutylamino)-styryl}-1 methylpyridinium iodide (DBASMPI) doped DNA polymer gel was obtained by soaking it in dye solution. We observed optical properties of dye-doped DNA polymer gel. Amplified spontaneous emission (ASE) properties of dye-doped DNA polymer gel at ambient temperature were investigated. We measured the intensity of output light from samples as a function of pump pulse energy in order to determine the threshold energies. The emission spectra were obtained under several values of excitation intensity to confirm spectral narrowing. We discussed the lasing capability by dye-doped DNA polymer gel.

We report the influence of nitrogen implantation and annealing on the microstructures and photocatalytic properties of a nanostructured titania (TiO₂) film. Titania samples were implanted at 40 keV and ion dose range of 10¹⁶/cm² to 4×10¹⁶/cm². From X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses it was found that the anatase phase of titania predominated with small amount of brookite, and the structure was stable at annealing temperatures up to 973 K. The samples showed narrower XRD peaks corresponding to larger mean-grain sizes comparing to the un-implanted titania samples. The SIMS (secondary ion mass spectroscopy) nitrogen depth profile showed a maximum nitrogen concentration at about 70 nm beneath the film surface. The absorption edge of the titania samples as measured using spectrophotometer was found to shift toward longer wavelengths with the increase of ion dose. The experiments of photodegradation of phenol were performed under a UV illumination for the N-implanted titania film which exhibited improved photocatalytic properties with the increase of annealing temperature.

We succeeded to prepare the microsphere of polymer to which the marine DNA was doped. Moreover, ASE (Amplified Spontaneous Emission) was observed since the optical property of the microsphere to which the DNA was doped was discussed. In addition, an excellent optical property was found being shown in the comparison with DNA doped polymer thin film. The DNA shows a very interesting optical property like the improvement of the fluorescent intensity and the control of the concentration quenching of the dye by inserting the functional dye between the base pairs. On the other hand, the research using the surface is advanced to the microsphere for the reasons why the surface area is large. Light can be confined highly effective in the miniature space, and the microsphere of polymer is a material that is promising as optical micro cavity.

Painless and portable blood extraction device has been immersed in the world of miniaturization on bio-medical research particularly in manufacturing point-of-care systems. The fabrication of a blood extraction device integrated with an electrolyte-monitoring system is reported in this paper. The device has advantages in precise controlled dosage of blood extracted including the slightly damaged blood vessels and nervous system. The in-house blood diagnostic will become simple for the patients. Main components of the portable system are; the blood extraction device and electrolyte-monitoring system. The monitoring system consists of ISFET (Ion Selective Field Effect Transistor) for measuring the concentration level of minerals in blood. In this work, we measured the level of 3 ions; Na+, K+ and Cl-. The mentioned ions are frequently required the measurement since their concentration levels in the blood can indicate whether the kidney, pancreas, liver or heart is being malfunction. The fabrication of the whole system and experimentation on each ISM (Ion Sensitive Membrane) will be provided. Taking the advantages of LIGA technology, the 100 hollow microneedles fabricated by Synchrotron Radiation deep X-ray lithography through PCT (Plane-pattern to Cross-section Transfer) technique have been consisted in 5x5 mm² area. The microneedle is 300 μm in base-diameter, 500 μm-pitch, 800 μm-height and 50 μm hole-diameter. The total size of the blood extraction device is 2x2x2 cm³. The package is made from a plastic socket including slots for inserting microneedle array and ISFET connecting to an electrical circuit for the monitoring. Through the dimensional design for simply handling and selection of disposable material, the patients can self-evaluate the critical level of the body minerals in anywhere and anytime.

This paper presents our latest results on the designs, fabrication and calibration of two micro accelerometers and a convective based gyroscope, as well as their combination to create a motion sensor for inertial navigation applications. Among the two accelerometers, the first one is a 3-DOF micro accelerometer utilizing piezoresistive effect in single crystal silicon. The sensing structure consists of four sensing-beams surrounding a seismic-mass. Therefore, the sensor is smaller than the cross-beam type accelerometer. The second accelerometer is a dual axis thermal accelerometer, working based on the thermo-resistive effect of silicon thermistors in free convective regime. Since no seismic mass is used, the shock-resistance becomes very high (up to 9.0×10⁶g). The novel structure of the thermistors eliminated up to 93% of stress induced by temperature. The dual-axis gas gyroscope proposed here is working based on the thermo-resistive effect of light-doped silicon thermistor and the force convective heat transfer. The sensor configuration consists of a gas pump and a micro thermistor sensing element, packaged in an aluminum case with overall diameter and length of 14mm and 25mm, respectively. Unlike vibrating gyroscopes reported recently in MEMS-field, our gyroscope has "no" seismic mass; therefore it can eliminate the inherent problems such as fragility, low shock-resistance, squeezed-film air-damping, etc. Moreover, since the driving power for the moving mass is not necessary, the power consumption is also reduced. Finally, an algorithm to process the signal from a system consists of a 3-DOF accelerometer and 3-DOF gyroscope is presented. In this algorithm, quaternion based calculation was applied instead of Euler angles, therefore the problems of singularity or complicated trigonometric calculations can be avoided. The algorithm can be applied for inertial navigation systems (INS).

DNA-CTMA solutions in ethanol doped by various azobenzene compounds were prepared and their absorbance transition by irradiate UV were measured. It was found that trans-cis transition took place in the cases of doped azobenzene and azobenzene-4,4'-dicarboxylic acid diethyl ester(ADCDE). It did not depend for the speed of trans-cis transition of solution which doped both azobenzene and ADCDE to DNA-CTMA with those amount of doping. To the next DNA-CTMA films doped by azobenzene and ADCDE were prepared and their absorbance transition by irradiate UV were measured. Consequently, trans-cis transition took place only by only the films doped azobenzene and was not transferred by the films doped ADCDE. It was found that trans-cis transition of DNA-CTMA films doped by azobenzene (100:1) was faster than PMMA films doped same amount of azobenzene. It is considered that because azobenzene molecules were isolated by intercalation to DNA and the spatial flexibility of azobenzene molecules became large, the speed of trans-cis transition of azobenzene became early compared with the case where it doped to PMMA.

The increasing requirements for antenna apertures with multiple functions in terms of frequency diversity, beam steering and beam shaping have lead to the concept of re-configurable antennas. RF MEMS switch technology is promising to enable the development of such structures. Through electromagnetic analysis, this research demonstrates the feasibility of using RF MEMS switches to facilitate the phase shifting required for phased array beam steering. A particular problem associated with the practical implementation of RF MEMS switches, the substrate choice, was investigated. Ceramic substrates have appropriate loss tangent coefficients and dielectric constant, however, the thermal mismatch between silicon nitride and other materials used to construct the mechanical parts of the switch introduces thermal mismatch stress and process problems during fabrication. Micro RF relay switches on a ceramic substrate have been fabricated and their pull-in voltage characteristics were measured and compared to the theoretical results for the RF relays.

Advances in sensor technology and wireless communications have made networked micro-sensors possible, where each sensor individually gathers and transmits informations from the natural environment. This work aims to present an overview of the benefits and of the most recent advances in antenna technologies, investigating the possibility of integrating enhanced solutions in a large distributed wireless sensor network for the environmental monitoring. The goal of the work covered in this paper is in fact to investigate the possibilities of developing a radiating structure featuring low cost, reconfigurability and scalability for other frequency bands, adoptability in different communication systems, reproducibility and at the same time incorporating wide functionality. The antenna in fact is the key element in order to fully integrate a wireless microsystem on a single chip. The integration requires a small antenna on a low-loss substrate material compatible with the microelectronic devices. EBG structures are typically two or three dimensional periodic media characterized by the capability to inhibit the electromagnetic wave propagation for each angle and each polarization in a specific frequency band. These optimized synthetic materials can represent an opportunity for the development and design of innovative electromagnetic devices. The EBG structures, being complex structures, present different degrees of freedom, that can be used to optimize the performances of the application they are used for, e.g. printed antennas. An integrated design technique of the wireless device, built with printed patches on a complex dielectric substrate is here presented.

Although coordinate metrology has reached a very high state of development concerning versatility and accuracy for common engineering parts, a high precision capability with nano scale resolution and accuracy is often hard to achieve when it is required to measure very small parts and features. The limiting component is the bulky probing system of traditional CMMs (coordinate measuring machines). In order to satisfy increasing demand for highly accurate geometrical measurements on small parts and small structures, a new measuring probe of high sensitivity and small geometrical dimension with low contact forces needs to be developed. In this paper, a novel probing system, which combines a FBG (Fibre Bragg Grating) embedded optical fibre tactile probe with an optical sensing technique, has been proposed. With the sensor elements integrated into the probe tip directly, the system sensitivity can be increased significantly. A preliminary theoretical analysis of the sensitivity of the FBG fibre sensor under axial and lateral end point loading has been presented and the results show that this micro scale probe has great potential to realize a resolution of 1nanometer on geometrical measurement of small parts.

This paper investigates the transient heat transfer behavior and doping concentration of the thermomechanical microprobe using the transient finite element method and SUPREM-IV.GS software for the experimental validation. The thermomechanical microprobe is a newly developed high-density data storage technique. Heat management, on the other hand, is an extremely critical issue in high-density data storage application. This study explores the transient heat transfer behavior of the thermomechanical microprobe through measurement and simulation. In order to study this transient heat transfer behavior, a microprobe is fabricated, and the transient finite element method is adopted for optimizing and analyzing the performance of the microprobe. Furthermore, the doping parameter would govern the data writing and reading response of the thermomechanical microprobe. To optimize the microprobe's performance, this paper also utilizes the process simulation software SUPREM-IV.GS as well as the area weighting method to predict the electrical characteristic of the microprobe. The main goal of this research is to develop a ethodology for the required heating/cooling rate to reach the expected temperature which is affected by the different geometric specifications of the cantilever beam structure of the microprobes. Furthermore, this research fabricates the thermomechanical microprobe using complementary metal oxide semiconductor (CMOS)-compatible micromechanical manufacturing technology. The results show that the required time response to reach the designed heating temperature is about a few microseconds for a small-sized heater. Moreover, in terms of temperature cooling status, we find that the larger dimension of a cantilever beam can enhance the heat dissipation from the heater in order for the expected temperature to be reached within the time range of microseconds. In addition, the resistivity of the heater obtained from the simulation prediction based on the SUMPEM-IV.GS and the area weighting method corroborates the experiment data in the literature.

Application of thin polymer film as storing mean for non-volatile memory devices is investigated. Capacitance-voltage (C-V) measurement of metal-ferroelectric-metal device using ferroelectric copolymer P(VDF-TrFE) as dielectric layer shows stable 'butter-fly' curve. The two peaks in C-V measurement corresponding to the largest capacitance are coincidental at the coercive voltages that give rise to zero polarization in the polarization hysteresis measurement. By comparing data of C-V and P-E measurement, a correlation between two types of hysteresis is established in which it reveals simultaneous electrical processes occurring inside the device. These processes are caused by the response of irreversible and reversible polarization to the applied electric field that can be used to present a memory window. The memory effect of ferroelectric copolymer is further demonstrated for fabricating polymeric non-volatile memory devices using metal-ferroelectric-insulator-semiconductor structure (MFIS). By applying different sweeping voltages at the gate, bidirectional flat-band voltage shift is observed in the ferroelectric capacitor. The asymmetrical shift after negative sweeping is resulted from charge accumulation at the surface of Si substrate caused by the dipole direction in the polymer layer. The effect is reversed for positive voltage sweeping.

Silicon quantum dots (SiQDs) embedded in silicon dioxide are being investigated as a means of engineering a wide band gap semiconductor for potential application in silicon based tandem solar cells. The conductivity of the self-organized silicon dots embedded in the oxide is an important parameter in characterizing the electronic transport mechanisms. We present in this paper our initial results on measurement of the resistivity as a function of temperature. In order to reduce contact resistance aluminium contacts are annealed to induce spiking through upper layers of oxide and thus producing a large contact surface area. Samples with various initial silicon rich concentrations are compared. Activation energies for various tentative conduction mechanisms are calculated from this data and possible conduction models presented.

This contribution is focused on plasma-enhanced chemical vapor deposition systems and their unique features that make them particularly attractive for nanofabrication of flat panel display microemitter arrays based on ordered patterns of single-crystalline carbon nanotip structures. The fundamentals of the plasma-based nanofabrication of carbon nanotips and some other important nanofilms and nanostructures are examined. Specific features, challenges, and potential benefits of using the plasma-based systems for relevant nanofabrication processes are analyzed within the framework of the "plasma-building unit" approach that builds up on extensive experimental data on plasma diagnostics and nanofilm/nanostructure characterization, and numerical simulation of the species composition in the ionized gas phase (multicomponent fluid models), ion dynamics and interaction with ordered carbon nanotip patterns, and ab initio computations of chemical structure of single crystalline carbon nanotips. This generic approach is also applicable for nanoscale assembly of various carbon nanostructures, semiconductor quantum dot structures, and nano-crystalline bioceramics. Special attention is paid to most efficient control strategies of the main plasma-generated building units both in the ionized gas phase and on nanostructured deposition surfaces. The issues of tailoring the reactive plasma environments and development of versatile plasma nanofabrication facilities are also discussed.

This paper presents a method to form thick spin-on glass (SOG) sacrificial layer for accelerometer encapsulation fabrication. SOG is chosen as the sacrificial material because it is easy to apply, has good thickness uniformity, and can be easily etched back before densification. Siloxane type SOG is applied on blank wafers and accelerometer patterns by multiple spin, bake, and cure processes. A series of gradual hot plate baking up to 250°C are experimented for each spun layer. After multiple spin and bake, the SOG layers are etched back in hydrofluoric acid (HF) solution of various concentrations to form rectangular encapsulation bases. 25 samples are prepared for SOG thickness uniformity characterization. Center thickness and four perimeter thickness measurements are taken for each sample using thin-film mapper. These five measurements are averaged to get sample thickness. Two surface profiler measurements are taken for each sample perpendicularly to each other using Tencor surface profiler. The minimum reading is subtracted from the maximum reading to get sample variation. Upon SEM inspection, mildly sloped etched walls from HF etching are observed. No surface cracking was visible. Shallow trench patterns are apparent on SOG deposited on accelerometer pattern. The average sample thickness is 5 μm with 3.7% thickness variation across samples. The average variation within each sample is 0.14 μm with an average of 2.6% thickness variation within sample. These thickness variations are acceptable for encapsulation structure deposition.

For improving the sensitivity of a SPR biosensor, we proposed a new combination of the thin silver (Ag) and SiO₂ films, and used the common-path heterodyne interferometry. Although the Ag film has higher sensitivity than the gold (Au) film¹, but Ag has toxicity for many media and it is easy to be oxidized. In order to enhance the sensitivity and protect the tested medium not to directly contact with Ag, we selected a coating of SiO₂ on the Ag film for the reason of it is cheaper and easy to obtain. The simulations and experimental results are shown that its best resolution could reach to the value of 6.9×10^-9RIU.

The explosive properties of porous-silicon, impregnated with an oxidant, were researched. The electrochemical etching of porous silicon layers was investigated, and a porous layer structural model is proposed to model the pore and crystallite dimensions of the porous layer. A gravimetric experimental technique is described whereby the pore dimensions and specific surface area can be determined. A new relationship between pore size and specific surface area was established. The types of oxidants and their properties, as well as the impregnation of the porous layers by different oxidants, were researched. It was observed that the filling of the pores by the oxidant is a function of pore diameter, specific surface area and type of oxidant used. The experimentally observed explosive properties are a function of silicon resistivity, porous layer porosity and pore dimensions. It was found that there is an optimum pore size for the most energetic explosion. Future applications for this new technology are proposed.

A new atmospheric pressure plasma electrolytic process has been developed for the deposition of TiO₂ crystalline thin films on metal substrate. Contrary to the other deposition techniques, the process occurs in a liquid precursor, composed of titanium tetraisopropoxide and absolute ethanol. A plasma discharge is created and confined around the cathode in a superheated vapour sheath surrounded by the liquid phase, inducing the production of a thin TiO₂ coating at the surface of the cathode. Because of the flexibility of the operating parameters, this technology allows the rapid deposition of thin films with a wide range of structural and physical properties. This process enables therefore the production of nanocrystalline titania films with adjustable morphology and structure (anatase, rutile) by adjusting the operating voltage, current intensity, the treatment time and calcination temperature. The analysis of the structure and composition of these TiO₂ coatings have been carried out by Scanning Electron Microscopy, Transmission Electron Microscopy, Raman spectroscopy, X-ray Photoelectron Spectroscopy and X-Ray Diffraction. A thorough study has been performed to understand the influence of the operating parameters on the properties and structure of the coatings.

We studied composites of single walled carbon nanotubes and poly(3hexylthiophene) by optical absorption, X-ray diffraction and transmission electron and scanning tunneling microscopy. Dispersing single walled carbon nanotubes in poly(3hexylthiophene) leads to sharpening of vibronic structure and enhanced optical absorbance near the band edge. We show that the enhanced order in the polymer is due to templating of the polymer chains by the surface of the carbon nanotubes leading to increased electronic delocalization.

Self-sustaining Nickel membranes with periodic and regular distribution of pores, in the scale of hundred of nanometers, were produced by interference lithography and electroplating. The process consists in the recording of submicrometric 2D periodic photoresist columns, on a metal-coated glass substrate, using the double exposure of an interference fringe pattern. As the photoresist is a good electrical isolator, when the sample is immersed in a Ni electroplating bath, the array of photoresist columns impedes the Nickel deposition in the patterned areas. A nickel film is then growth among the photoresist columns with a thickness up to 80 % of the height of the columns. In order to release the submicrometric membrane from the substrate, a thick hexagonal Nickel sustaining structure is electroformed, using conventional photolithography. The dimensions of the sustaining structure can be adapted in order to fulfill the pressure requirements of the filtration system. The good uniformity of the pore sizes as well as the smooth of the surface make such devices very interesting for separation of particles by size in filtration systems.

A new simplified heterojunction phototransistor (HPT) circuit model is given in this paper. Most of papers use Ebers-Moll model to describe the optical-electrical relations of HPT. Which is a physical based model and must be changed with different device structure. In this paper, an empirical model is employed. This model mainly formed by three parts: the photo current (I_ph), base current (I_b) and collector current(I_c). A dependent current source is used to model the photo current between the collector and base. The photo current can be different from different optical power. Ib are depend on base-emitter voltage while Ic is a function of collector-emitter voltage, I_b and I_ph. Contrast with the Ebers-moll model, the empirical model greatly reduced the complexity of the circuit. The model parameters are extracted on measured Ic-Vce and gummel plots. Then, dates in some documents were used to test the empirical model. There is a good agreement with the measured results.

The effect of a buffer layer and/or interface region on the photovoltaic properties of Al-doped ZnO (AZO)/Cu₂O heterojunction solar cells was investigated. The I-V characteristics and photovoltaic properties in AZO/ZnO-In₂O₃/Cu₂O devices were considerably improved by increasing the Zn content (Zn/(In+Zn atomic ratio)) of the ZnO-In₂O₃ thin-film buffer layer. In addition, the photovoltaic properties of AZO/Zn_1-XMg_XO/Cu₂O devices were found to degrade significantly as the composition (X) was increased above approximately 0.1 because of the increase in resistivity of the buffer layer. Although the spectral response of photocurrent observed in AZO/Zn_1-XMg_XO/Cu₂O devices was considerably affected by altering the value of X, the photo-generated hole in the buffer layer of these devices was not successfully injected into the Cu₂O. AZO/Cu₂O heterojunctions fabricated using Cu₂O sheets with a sulfurized surface exhibited ohmic I-V characteristics.

Soft magnetic composite materials find increasing use in electrical motors, replacing existing laminate materials. In this study, the composites have been fabricated with micro- and nano-sized highly pure iron powders coated by polyester and phenolic resins. Soft magnetic composite materials have been pressed into ring type for magnetic properties measurement, and bar type for mechanical properties measurement over the pressure range up to 870 MPa. Some samples have subsequently been heat treated to 300°C. The effect of the amount of organic materials on the magnetic properties like as permeability, magnetic flux density, core loss and green density were investigated. And electrical resistivities were also examined. On the addition of the organic coating materials of 5 wt%, green density of the compacted composites is most high of 6.9 g/cm³, and magnetic properties are also better. For the case of 5 wt% polyester resin, the effect of powder size with 100 nm, 3 μm, 10 μm and 53 μm were examined. Both the green density and the magnetic properties are best for the particle size of 10 μm. Fine particles below 3 μm easily agglomerate each other, and homogeneous coating of each particle surface is difficult.

Thermoelectric conversion based on the thin film of thermoelectric materials has the advantages of integration, flexibility and miniaturization. A thin-film flexible thermopile power generator has practical application in a free-form surface due to its flexibility. Such a generator also has the potential to be used as a wearable power-source. We proposed a thermopile composed of Bi₂Te_2.5Se_0.5 and Bi_0.5Sb_1.5Te₃ as thermoelectric materials formed on a polyimide sheet with a heat absorber sheet and a heat sink sheet. BiTe was used as the thermoelectric material, because it has highest performance around room temperature. Thin films of the thermoelectric materials were deposited on a polyimide sheet by the DC sputtering and lift-off process. There were 380 thermocouples fabricated on the sheet. A flexible thermopile power generator was formed when a substrate polyimide sheet bent into a wavy form and the set between a flexible heat absorber and sink sheets. Hot and cold junctions were formed when the substrate was bent into a wavy form. Due to this wavy form and slits in the thermopile sheet, heat absorber and sink sheets, the thermopile generator could be bent in two orthogonal two directions. The fabricated thermopile had a length of 66 mm, a width of 38 mm and a height of 2.5 mm. The average output voltage was 160 μV/K per thermocouple. This result was about 41% of the theoretical value. However, a high-resistivity of p-type BiTe thin-film was obtained because of a poor crystalline structure. The achieved resistance of 110mΩ•cm was 130 times greater than that of the sputtering target. In addition, the low continuity of brittle thermoelectric materials leads to low flexibility. Therefore, we investigated this problem by using x-ray diffraction and electron probe microanalysis. We propose a novel structure and fabrication technique that solves these problems and enhances the potential use of flexible thermopile generator in practical applications.

The silicon pressure sensor has been developed for over thirty years and widely used in automobiles, medical instruments, commercial electronics, etc. There are many different specifications of silicon pressure sensors that cover a very large sensing range, from less than 1 psi to as high as 1000 psi. The key elements of the silicon pressure sensor are a square membrane and the piezoresistive strain gages near the boundary of the membrane. The dimensions of the membrane determine the full sensing range and the sensitivity of the silicon sensor, including thickness and in-plane length. Unfortunately, in order to change the sensing range, the manufacturers need to order a customized epi wafer to get the desired thickness. All masks (usually six) have to be re-laid and re-fabricated for different membrane sizes. The existing technology requires at least three months to deliver the prototype for specific customer requests or the new application market. This research proposes a new approach to dramatically reduce the prototyping time from three months to one week. The concept is to tune the rigidity of the sensing membrane by modifying the boundary conditions without changing the plenary size. An extra mask is utilized to define the geometry and location of deep-RIE trenches and all other masks remain the same. Membranes with different depths and different patterns of trenches are designed for different full sensing ranges. The simulation results show that for a 17um thick and 750um wide membrane, the adjustable range by tuning trench depth is about 45% (from 5um to 10um), and can go to as high as 100% by tuning both the pattern and depth of the trenches. Based on an actual test in a product fabrication line, we verified that the total delivery time can be minimized to one week to make the prototyping very effective and cost-efficient.

When an organic solution of a polymer is dropped on a hydrophilic surface, e. g. a glass substrate, polymer film is dewetted on the surface during evaporation of solvent, leaving several polymer patterns such as stripes, dots (domes) and polygon networks. Dewetting phenomena are not only observed in polymer films but also in low mass molecular films. A cyanine-dye complex was prepared from a cationic cyanine dye and an anionic amphiphile. When a chloroform solution of the cyanine complex was spread on a glass substrate by a roller, micro-domes of the cyanine-dye complex formed in dewetted films. The roller draws the three-phase line (the air-solid-liquid boundary of the droplet of the chloroform solution) with a constant rate, which leads to a two-dimensional ordered array of micro-domes. Typically, the size of micro-domes obtained were several or several ten micrometers in width and one micrometer in height. The diameter and height of micro-domes depended on the roller speed. Fluorescence microscopy shows that the cyanine-dye complex is condensed in each micro-dome. The micro-domes consist of polycrystals and gave fluorescence emission that was difference from a chloroform solution of the cyanine-dye complex.

The 3D structural shape-control using Synchrotron Radiation (SR) lithography for the configurations of less than a micron-size has been realized. The fabrication process will be described in details. Moreover, the structure with aspect ratio as high as 4 was achieved. The briefly introduced fabrication process is to deposit a PMMA (polymethylmethacrylate) layer to a silicon substrate by spin coating. The layer is used as the X-ray resist. Subsequently, to expose SR onto the resist through an X-ray mask, then to develop the exposed resist. The principal shape-control is accomplished by optimizing each parameter influencing the resist formation, the exposed SR dosage, and development time. All mentioned above are the parameters determined from the fabrication of an arbitrary shape which is the main purpose in this paper. The targeted evaluation of the fabricated structures is to provide the line and space of 1μm pitch, 1.9μm line-height, and aspect ratio of 4. The technique for optimization of the experimental condition and each parameter for the fabrication process will be explained in the paper. This research is expected to be useful for other related work on manufactures of sub-micron structure. The suggested applications are; a variety of optical elements such as the polarized light beam splitters, diffraction optical elements, and a number of applications in device or system which requires nanoscale structures will find this work employable. The fabrication technique of higher aspect ratio and narrower line-width will be investigated in the future research.

Lead magnesium niobate-lead titanate ((1-x) Pb (Mg_1/3Nb_2/3-xPbTiO₃, PMNT) solid solution thin films were prepared on silicon substrates by Sol-Gel method. The well crystallized thin films were prepared on 700°C for 1 hour and micro-patterning of PMNT thin films were researched by wet etching. PMNT etch rate higher than 2.4μm/min could be obtained with well etch profile by using HF/HNO₃/H₂O. XRD analysis and ferroelectric property test showed that there were not the crystal lattice distortion and ferroelectric property change during PMNT etching. In the paper, the key technologies in the preparation and patterning of PMNT thin films were solved and had laid good technology foundation for the preparation of silicon-base ferroelectric thin film microfabricated devices.

A nanoelectromechanical model based on atomistic simulations including charge transfer was investigated. Classical molecular dynamics method combined with continuum electric models could be applied to a carbon-nanotube nanoelectromechanical memory device that could be characterized by carbon-nanotube bending performance by atomistic capacitive and interatomic forces. The capacitance of the carbon atom was changed with the height of the carbon atom. We performed MD simulations for a suspended (5,5) carbon-nanotube-bridge with the length of 11.567 nm (L_CNT) and the depth of the trench of 0.9 ~ 1.5 nm (H). After the carbon-nanotube collided on the gold surface, the carbon-nanotube-bridge oscillated on the gold surface with amplitude of ~1 Å, and the amplitude gradually decreased. When H ≤ 1.3 nm, the carbon-nanotube-bridge continually contacted with the gold surface after the first collision. When H ≥ 1.4 nm, the carbon-nanotube-bridge stably contacted with the gold surface after several rebounds. As H increased, the threshold voltage linearly increased. As the applied bias increased, the transition time exponentially decreased at each trench depth. When H / L_CNT was below 0.13, the carbon-nanotube nanoelectromechanical memories were permanent nonvolatile memory devices, whereas the carbon-nanotube nanoelectromechanical memories were volatile memory or switching devices when H / L_CNT was above 0.14. The turn-on voltages and tunneling resistances obtained from our simulations are compatible to those obtained from previous experimental and theoretical results.

We are currently developing basic building blocks for creating digital logic units that are based on mechanical components. Transistors, which are semiconductor devices, rely on doping to change intrinsic semiconductor to extrinsic semiconductors. However, at low or high temperatures, that control is impossible as semiconductors revert to intrinsic behaviour. Also, semiconductors exhibit various complications under ionizing (radiation) environment. We have fabricated logic units using micro-mechanical relays using MEMS technology. The logic units consist of a micro-mechanical relay with three electrical gates. The mechanical relay is fabricated with a cantilever over an airgap, and is operated by applying voltage to the gate. The applied voltage creates an electric force between the gate and a cantilever structure. The electrostatic force arches the cantilever into electrical contact. Since the operation does not depend on controlling the type of charge carriers, the proposed method does not suffer from the limitations shared by semiconductors. With different input combinations applied to the gates of the device, development of MEMS mechanical logic, leading to general digital circuits, is possible. Characterization of the devices is performed, which includes operation times, operation voltages, and maximum currents. Design, fabrication and testing of these micro-mechanical logic elements will be presented in the paper.

The surface structure and chemistry of polymers affect their functionality for a great range of applications in areas as diverse as biosensors, corrosion protection, semiconductor processing, biofouling, tissue engineering and biomaterials technology. Some of those applications require purposeful tailoring of laterally differentiated regions (e.g., array structures for multi-channel/multi-analyte biosensors and patterning for promotion of selective adhesion of cells/proteins). While such tailoring is currently taking place on the μm-scale, it is likely in the future to progress into the nm-regime. Attachment of biological moieties at surfaces and interfaces has been shown to be highly dependant on local chemistry at the intended site of attachment. Additionally, the local molecular-scale geometry may promote or hinder attachment events, as in the case of biofilms. To date, however, the effect of frictional properties of surfaces for chemical and biomolecular attachment is a much less understood phenomenon. In this study we show controlled patterning of a polymer surface (polydimethylsiloxane (PDMS)) arising from manipulation by Atomic Force Microscopy (AFM). PDMS is a bio-active/selective polymer having a broad range of applications, such as biomedical devices, molecular stamps, hydraulic fluid devices and in soft lithography. The polymer surface has been selectively altered by high speed scanning in order to generate regions on the surface that exhibit differentiated frictional properties. By altering the loading force, scan width, and area of the AFM probe-to-polymer contact it is possible to produce a variety of detailed and complex patterns with frictional contrast, including anisotropic frictional gradients on the polymer surface. The controlled manipulation of the polymer surface can be carried out on the micro-, meso- and nano-scale.

Micron sized structures/components are commonly employed in a variety of devices (e.g., biosensors, array devices). At present such devices are based on macroscopic technologies. Future applications of differentiated structures/surfaces are expected to place considerable demands on down-sizing technologies, i.e. enable meso/nanoscopic manipulation. An emerging set of methods known collectively as soft lithography is now being utilised for a large variety of applications including micromolding, microfluidic networks and microcontact printing. In particular stamps and elastomeric elements can be formed by transfer of a pattern to a polymer by a master. The 'master' can be fabricated by a variety of techniques capable of producing well-defined surface topographies. Established lithographic techniques used in the microelectronic industry, such as photolithography, are generally used to fabricate such master templates at the micron scale. A number of polymers can be used to transfer patterns. One of the most widely used polymers for pattern transfer has been polydimethylsiloxane (PDMS). The elastomer is chemically resistant, has a low surface energy and readily conforms to different surface topographies. Obtaining a master is the limiting factor in the production of PDMS replicas. In this study we demonstrate the use of Diamond-Like-Carbon (DLC) as a master template for producing PDMS micro/nano stamps and 3 dimensional PDMS structures. Intricate surface relief patterns were formed on the DLC surface from lithographic techniques by Atomic Force Microscopy (AFM) operated in the electrical conductivity mode. Attributes of the technique include: -Features with line widths less than 20 nm can be formed on the DLC. -The radius of curvature at edges can be less than 10 nm. -The slope of the features is limited by the aspect ratio of the tip. -Highly complex shapes can be fashioned. -Feature depth can be controlled by DLC film thickness and/or by the bias voltage applied. -The master is highly durable. -The master relief after patterning is extremely flat.

The general principles of optical design based on the theories of reflection, refraction and diffraction have been rigorously developed and optimized over the last three centuries. Of increasing importance has been the ability to predict and devise new optical technologies designed for specific functions. A key design feature of many of today's optical materials is the control of reflection and light transmittance through the medium. A sudden transition or impedance mismatch from one optical medium to another can result in unwanted reflections from the surface plane. Modification of a surface by creation of a gradual change in refractive index over a significant portion of a wavelength range will result in a reduction in reflection. An alternative surface modification to the multi layered stack coating (gradient index coating) is to produce a surface with structures having a period and height shorter than the light wavelength. These structures act like a pseudo-gradient index coating and can be described by the effective medium theory. Bernhard and Miller some forty years ago were the first to observe such structures found on the surface of insects. These were found in the form of hexagonally close packed nanometre sized protrusions on the corneal surface of certain moths. In this study we report on similar structures which we have found on certain species of cicada wings demonstrating that the reflective/transmission properties of these natural nano-structures can be tuned by controlled removal of the structure height using Atomic Force Microscopy (AFM).

For this study, Ti/Si and Ta/Si structures were implanted with two doses of nitrogen 10¹⁵ ions/cm² (low dose) and 10¹⁷ ions/cm² (high dose) at 10KeV and 20KeV energy. Characterization was performed by Sheet resistance measurement and X-Ray diffraction (XRD) techniques. Results shows that implantation of 10¹⁵ ions/cm² dose of nitrogen does not cause any nitridation, while in case of high dose implanted samples formation of tantalum nitride phase was observed. Nitride layers formed this way was used as diffusion barrier layers for copper metallization in Silicon based integrated circuits.

Nanoparticle manipulation by various plasma forces in near-substrate areas of the Integrated Plasma-Aided Nanofabrication Facility (IPANF) is investigated. In the IPANF, high-density plasmas of low-temperature rf glow discharges are sustained. The model near-substrate area includes a variable-length pre-sheath, where a negatively charged nanoparticle is accelerated, and a self-consistent collisionless sheath with a repulsive electrostatic potential. Conditions enabling the nanoparticle to overcome the repulsive barrier and deposit onto the substrate are investigated numerically and experimentally. Under certain conditions the momentum gained by the nanoparticle in the pre-sheath area appears to be sufficient for the driving ion drag force to outbalance the repulsive electrostatic and thermophoretic forces. Numerical results are applied for the explanation of size-selective nanoparticle deposition in the Ar+H₂+CH₄ plasma-assisted chemical vapor deposition of various carbon nanostructure patterns for electron field emitters and are cross-referenced by the field emission scanning electron microscopy. It is shown that the nanoparticles can be efficiently manipulated by the temperature gradient-controlled thermophoretic force. Experimentally, the temperature gradients in the near-substrate areas are measured in situ by means of the temperature gradient probe and related to the nanofilm fabrication conditions. The results are relevant to plasma-assisted synthesis of numerous nanofilms employing structural incorporation of the plasma-grown nanoparticles, including but not limited to nanofabrication of ordered single-crystalline carbon nanotip arrays for electron field emission applications.

We report a naturally grown stripe structure with a nanometer scale wavelength in REBa₂Cu₃O_7-δ (RE = Sm and Eu) superconductors investigated with scanning tunneling microscopy (STM) and transmission electron microscopy (TEM). Such a periodic array was unveiled owning to the 3 dimensionally spatial oscillation of RE and Ba around the stoichiometric ratio. The study displayed that novel nanostripes function as robust pinning sites and effectively enhance the peak effect and the irreversibility line at 77K. This illustrates an approach to fabricate high performance REBa₂Cu₃O_7-δ superconductors for application in liquid nitrogen temperature.

We present a theoretical model for an atomic diode made up of two one-dimensional semi-infinite linear arrays which are separated by a distance d on a surface substrate. By the use of one-dimensional Green's functions we obtain the local density of states (LDOS) of the system for the continuum limit appropriate to metallic adsorbates and the tight-binding model appropriate to semiconductor adsorbates. The I-V characteristics are studied in the limit of a weakly coupling perturbation between the linear arrays of atoms as well as the limit where the inter-array potential is strongly influenced by an electric field. The latter means that there is strong dependence of the tunneling amplitudes on the applied field which are calculated using suitably modified transfer matrix method.

Simulations for deformed shape-predictions of the 3-dimensional microstructures fabricated by Plane-pattern to Crosssection Transfer (PCT) Technique and Synchrotron Radiation (SR) lithography are described in this paper. We have attempted to study on a nonlinear relation between X-ray dosage and depth of the structure in the past work. The shapeprediction was investigated from two pairs of parameters influencing the structural deformation; dose-depth and position-dose. However, the above simulations resulted as, the higher height of the structure, the more error margin observed. A possible cause could be the etching direction dependent on the developing time. Thus, we currently emphasize on the factor causing this error. In order to comprehend the mechanism of the factor, the mathematical system of X-ray energy distribution onto PMMA (poly-methylmethacrylate) resist has been developed. The shape-prediction is consequent of the simulations based on calculations from the mathematics software. The investigation of the system enhances a possibility for higher accuracy of the prediction. In addition, the desired shapes can be confirmed by the simulations before the mask design and running experiments. The mathematical system for energy distribution dependents on the SR light source, X-ray mask specification, and resist specification. As a result, the predicted structures relevant to the absorbed energy-depth-position parameter set and absorbed energy-etching rate parameter set were obtained from this system. The simulations for shape-prediction were completed by the above parameter sets with the simulation software, MATHEMATICA^(R). Graphic displays of predicted shapes are provided in the paper for clearly understanding.

VO₂ thin films were prepared from V₂O₅ films using post-deposition annealing in vacuum. The films obtained have been studied by using XRD, XPS, SEM, UV-VIS and electrical measurements. The results show that the samples prepared at the optimal conditions before and after phase transition the resistance of VO₂ thin film changes about 10³ orders and the transmittance of 900nm light change 40%. Different preparation conditions can change the phase transition properties in VO₂ thin films. The structural properties of samples are improved but the phase transition properties are declined by the increase of annealing time and annealing temperature. The best reasonable annealing time and annealing temperature has been got by discussing the effects of annealing time and annealing temperature on the phase transition point and hysteresis width. Other factors that affect the optical and electrical properties in VO₂ thin films have also been discussed.

This paper implements modification of tungsten oxide film using ion implantation and a physical characterization of the film. The film was implanted with nitrogen at energies between 10 keV and 40 keV and ion dose range 10¹⁴−10¹⁶ cm^-2. The surface morphology of the film after implantation has been modified as observed using electron microscopy. The transmittance of the film was found to decrease with increasing implantation energy and ion dose as measured using conventional spectrophotometer. Depth profile of nitrogen was analyzed using Secondary Ion Mass Spectroscopy (SIMS) and found a peak of nitrogen across the depth of the implanted layer. The amount of nitrogen was found to increase with increasing ion dose and energy. From electron diffraction a broader diffraction rings were revealed from both the implanted and un-implanted layers, indicating that the crystalline properties of the tungsten oxide film after ion implantation remains the same.

This paper presents an investigation on the dynamic characteristics of a compliant bistable micromechanism. The analyzed bistable micromechanism has two stationary positions at the two extremes of the motion range, where the strain energies are local minimum. A bistable mechanism is a nonlinear system with a special stiffness. In this study, the compliant bistable micromechanism adopted was a well-known configuration. The central mass of the micromechanism was treated as a carriage to carry switching components, such as a mirror or an electrical contact. The dynamic characteristics of the bistable micromechanism would be significant in the application of switching devices. In order to verify the correctness of theoretical prediction on the dynamic characteristics, the designed micromechanisms were fabricated by MEMSCAP's PolyMUMPs^(R). In addition, a test rig incorporating the required instruments was then constructed for measuring the performance of the bistable micromechanism. From the experimental study, it revealed that good agreement between analytical and experimental results were obtained.

This paper studies spin-on glass (SOG) etching in T-shaped microchannels by hydrofluoric acid (HF). Since oxide etching by HF in microchannels is both reaction and diffusion limited, an etching model based on non-first order chemical reaction/steady-state diffusion sacrificial layer etching mechanism is presented to compensate for the etching effect at channel junction. Microchannels are formed on silicon substrate by deep reactive ion etching (DRIE). Samples with channel depth varying from 1μm to 6 μm are prepared by varying exposure time to reactant gas in DRIE chamber. Channel widths prior to the junction are varied from 2 μm to 10 μm while channel width beyond the junction is fixed at 5 μm. The channels are then filled with SOG by multiple spin, bake and cure processes. After etchback planarization using 5% HF solution, the samples are coated with 1.5 μm thick positive photoresist. An etch window is opened at channel fronts to expose underlying SOG. The samples are then time-etched in 5% HF solution and etch front propagation is observed under optical microscope through the transparent photoresist layer. It is observed that SOG etch rate in the microchannels is independent of channel width or channel depth. SOG etch rate at channel's T-junction is 0.67 times lower than etch rate in the straight channels preceding it due to HF concentration variation and etch product transfer rate variation effects. The proposed model fits experimental data well. Offset crosses vent pattern is determined as a good candidate for removing sacrificial oxide under an enclosed cap structure.

In this paper, influences of Fresnel diffraction for the advance accuracy in sub-micron resolution of the PCT (Planepattern to Cross-section Transfer) technique are discussed. Some analytical simulations were performed for a prediction of X-ray intensity distribution. The X-ray mask pattern employed in this work was a set of right triangles placed in double rows facing each other which was designed by the fact that when mask slit becomes narrower while approaching the corner, the influence of the diffraction gradually becomes more significant. In X-ray lithography, especially for optical applications, it has been realized that the Fresnel diffraction is most effective factor for designing the shape of slits in submicron. The group of triangle mask patterns has 1.48 μm-pitch and 20 μm-height with 0.5 μm-thick Ta absorber. The submicron structure was successfully fabricated by PCT with a proximity gap of 300 μm. The fabricated structure exposed by 1.84kJ/cm³ X-ray dose has 190 nm in height. The analysis was summarized by comparing the PCT simulations and the data from experimental results.

High-speed metal-based optical microscanning devices with low production cost and simple fabrication process wre successfully fabricated by direct deposition of piezoelectric materials using the aerosol deposition method (ADM) onto the micro-structured metal scanner frame. Large optical scanning angle of 35° at high resonance frequency of 23.6 kHz was achieved in ambient air without vacuum package. The scanner is applicable to SVGA high-resolution display of 800 x 600 or more. This method is a powerful tool for realizing ceramic integration with metal components.

The nanocontact printing process of non-planar substrate was conducted on the substrate as coated with the metal thin film on which the mask's pattern was to be printed by using the flexible h-PDMS stamp. In this study, in order to embody non-planar nanocontact print, the following types of nanostructures which were respectively different in a pattern form, a pattern size and a line width: a straight line type, an oblique line type, an L type and an U type. The mask size is 5 x 5 x 0.9 inch, and the pattern form size is 100nm ~ 500nm where the line width ratio and the pattern space are different and the depth is 200nm. The flexible h-PDMS stamp was fabricated by using VDT-731, SIP 6831.1, Fluka 87927 and HMS-301 as a mold material. The flexible h-PDMS stamp with a high resolution corresponds exactly to the master pattern, and could be replicated a pattern up to the size of 100nm. Also, in the surface characteristic, as a result of measuring the wettability, it could be known that the h-PDMS stamp has the surface characteristic of the hydrophobic and surface energy. The adhesion force and the friction force were very low. In the nanocontact printing of non-planar substrates experiment, a substrate of cylindrical on which the Cr adhesion layer of 100Å and the Au etching layer of 500Å were deposited by using the DC sputter and a substrate of ellipsoidal on which the Ti adhesion layer of 100Å and the Pd etching layer of 500Å were deposited in the form of a thin film, were fabricated, and a pattern was transferred to the substrates where to print by the flexible h-PDMS stamp wet with the SAM solution, and nanostructures had a high resolution without any defect could be fabricated. Also, we are seeking for its applicability to a organic electronic device, flexible electronic display, biological electronic device and the like by optimizing the nanocontact printing process.

A new technique incorporating combinatorial deposition to develop new multicomponent oxide and oxynitride thin-film phosphors by r.f. magnetron sputtering is demonstrated using subdivided powder targets. By sputtering with a powder target that is subdivided into two or more parts, phosphor thin films with a chemical composition that varied across the substrate surface could be successfully prepared. In Zn₂Si_1-XGe_XO₄:Mn thin films, for example, the chemical composition (Ge content (X)) could be optimized to obtain higher electroluminescent and photoluminescent emission intensities by using only one deposition with the new technique. As a result, a high luminances of 11800 and 1536 cd/m² for green emission was obtained in Zn₂Si_0.6Ge_0.4O₄:Mn TFEL device driven at 1 kHz and 60 Hz, respectively. In ((AlN)_1-X-(CaO)_X):Eu thin films, for example, the chemical composition (CaO content (X)) could be optimized to obtain higher electroluminescent and photoluminescent emission intensities by using only one deposition with the new technique. As a result, a luminance of 170 cd/m² for red emission was obtained in an ((AlN)_0.1-(CaO)_0.9):Eu TFEL device driven at 1 kHz.

This paper presents the fabrication and experiment of a flexible micro hollow cathode discharge device. The device is composed of three layers which are a thin anode layer, a insulation layer and a hollow cathode layer. The micro hollow cathode discharge occurs between two electrodes that have an array of holes with the diameter of 70 μm. The device has an array of 7 × 11 holes. The hollow cathode discharge usually has a characteristic of the high current density. The device is fabricated by micromaching technology. The micro hollow cathode is made by means of nickel electroplating in the photoresist mold. The material of the thin insulator is polyimide. Polyimide is spin-coated on a nickel layer and the anode is fabricated by thermal evaporation of aluminum. The thickness of the flexible discharge device is 50 μm and total size of the device is 20 mm × 10 mm. The test set up consists of a direct current high voltage source, a ballast resistor, a gas chamber and a CCD camera. The discharge test was performed in argon gas chamber at room temperature for various pressures. We measured the current while the discharge occurs for various voltages applied. Compared with macro discharge devices, this device operates at much higher pressure, even at 1 atm. The discharge appears at the applied voltage of 0.23 kV in 260 mm Hg. We observed the stable discharge. The device breaks down when the current is over 3 mA. The obtained current-voltage relationship is linear.

A new design for a high accuracy, 3-degree of freedom (DOF) MEMS manipulator is proposed. The 3-DOF robotic manipulator is to be used for biomedical applications such as cell probing, tissue sampling, neuron signal reading and drug delivery, in which high accuracy and repeatability of positioning is required. While sensing or imaging elements are not available in the integration with the manipulator to provide feedback for positioning, we investigated a calibration approach to minimize the positioning errors. In-plane and vertical MEMS thermal actuators are chosen to perform the required tasks. The modeling of the thermal actuators was first studied and the results match with experimental results. A calibration algorithm is implemented to allow the minimization of accumulated motion errors. The algorithm was successfully applied to the manipulator and results were obtained. A MATLAB script was written to simplify the calibration procedure. Problems faced in the design and potential solutions will be also discussed.

In this paper, silicon corrugated diaphragms with non-compensated and compensated mask layout have been fabricated on a single silicon (100) wafer by using potassium hydroxide (KOH) etching technique. Although, recently corrugated diaphragms have been used for a diaphragm structure due to its excellent properties, no theoretical and analytical studies on the fabrication process of these diaphragms have been performed. Therefore, the characterization of the KOH etching process with emphasized on convex corner behavior has been studied through both experiments and simulations in order to realize the perfect corrugated diaphragm. Details of the etching of corrugated diaphragms have been studied by using process simulation software of a three-dimensional anisotropic etching profile prior to fabrication process. The influence of the KOH etching temperature and concentration on the convex corner undercutting of corrugated diaphragm are observed. The convex corner behavior has been analyzed based on the geometrical parameters and the new emergent high index silicon planes. It was found that the convex corner undercutting phenomena is significantly reduced at low etching temperature and high KOH concentration respectively. It can be concluded that the prominent facets contributing to the undercutting of the convex corners of the corrugated diaphragm for the given etching condition coincide with the {411} plane. The introduction of the additional mask layout for the protection of convex corners at all convex-mask geometry of the corrugated diaphragm during the KOH etching process has been proved by simulation to produce almost perfect square corners. These simulation results have been confirmed by experiments.

Work is focused on the study and control of anisotropic silicon etching profiles by using conventional room temperature RIE system with SF₆/O₂ chemistry. The main process parameters of etching are considered in order to achieve high etching rate, high anisotropy, high aspect ratio, good selectivity, and all this achieved with good homogeneity and repeatability. High anisotropic etching profile, resulting in undercut less than 1.5 μm, aspect ratio higher than 10 and selectivity to oxide of 80 are obtained for 40 μm depth and 3.5 μm wide squared etched pillars. We determined that 29 % content of oxygen in total gas flow is optimal. Silicon and oxide etching rate and selectivity in dependence of total gas flow and gas flow ratio were investigated. Typically, silicon etching rate of 1.6 μm/min, oxide etching rate of 20 nm/min and selectivity of 80 were obtained. Due to the effect of load dependency of etching process, empirical dependence between load and etching rate was determined. Positive RIE lag is observed at etching high aspect ratio trenches. Etched trenches of 6 μm width (aspect ratio less than 7) revealed negligible influence of pressure on aspect ratio dependent etching, for etching performed at pressure 60 or 100 mtorr.

The paper investigates conditions for depositing perovskite-oriented strontium-doped lead zirconate titanate (PSZT) thin films using RF magnetron sputtering. PSZT is a material that can exhibit high piezoelectric and ferroelectric properties. The deposition was conducted using an 8/65/35 PSZT sputtering target. The effects of sputtering conditions and the deposition rates for films sputtered onto several surfaces (including gold and platinum coated substrates) were studied. Combinations of in-situ heating during sputtering and post-deposition Rapid Thermal Annealing (RTA) were performed and resulting phases determined. RTA was carried out in argon to observe their effects. The sputtered films were analyzed by Scanning Electron Microscopy (SEM), X-ray Diffractometry (XRD), and X-Ray Photoelectron Spectroscopy (XPS). Results show dramatic differences in the grain structure of the deposited films on the different surfaces. The stoichiometry of the sputtered films is demonstrated using XPS. In the case of gold and platinum coated substrates, sputtering was also carried out for different durations, to establish the growth rate of the film, and to observe the variation in grain size with sputtering duration. The deposited thin films were resistant to most chemical wet etchants and were Ion Beam Etched (IBE) at 19 nm/min.