Printing small geometries using wavelength of 248 nm on low- k materials is not a plug-in photolithography process from one technology to other technology node. In this paper, a method of film characterization of low-k dielectric materials will be discussed. For a characterization of chemical vapor deposited low-k dielectric materials, a positive tone deep UV (DUV) chemically amplified photoresist (CAR) was used as a poisoning gauge. In early development state of low-k dielectrics and copper dual damascene interconnects in back-end-of-line processes, unstable patterning behaviors were observed in spite of using an organic bottom antireflective coating layers on low-k substrates. The initial work was focused on finding the source of lot-to-lot critical dimension (CD) variations and understanding what causes this problem as well. Study indicated a strong correlation that photo CD depended on time interval between photolithography process and previous process step. Significant photo CD shift was introduced by short cycle time from thin film deposition to photolithography process and post via etch clean process to trench photolithography process. To minimize photo CD variations, the process optimizations were necessary in low- k dielectric film deposition, rework, via etch process, and post via etch clean process. As parallel efforts to improve lot-to-lot CD control, various photoresist system, different ambient annealing conditions, various surface organic and inorganic capping techniques were tested. In this experiments, time interval between processes was tightly controlled and maximized the worst case of scenario. Fresh and aged low-k dielectric films were analyzed using time-of- flight secondary ion mass spectrometry and x-ray photoelectron spectroscopy techniques. This work suggested that N2 containing in the film or introducing N2 into low-k dielectric film caused lot-ot-lot photo CD variations.
This paper presents integrated fault detection capability of the Spreeta biosensor technology. A specific feature is discussed based on multi-point image characterization. Multi-point image characterization provides a means to monitor biosensor surface damage, as well as sample anomalies such as macroparticulates are bubbles.
The use of in situ process monitoring equipment is becoming increasingly important in the drive to produce focal plan arrays more efficiently and at decreased cost. As part of Texas Instruments' modular approach to microelectronics manufacturing (microelectronics manufacturing science and technology, MMST), a number of internal process monitors and sensors have been developed. We describe the use of one such sensor, a spectral ellipsometer (SE) for in situ, real-time monitoring and control during infrared device fabrication. Using the SE we have demonstrated end-point detection for the removal of the air-contaminated surface layer of HgCdTe during a remote microwave hydrogen plasma cleanup process step. The SE is also being used to monitor the real-time growth of an interlevel MOCVD ZnS insulator. The spectral ellipsometer provides rapid feedback of film thickness, at a rate of about 10 Hz, enabling its use for process control. We describe the use of the SE for both the HgCdTe surface plasma etch cleanup and the ZnS deposition processes.
In situ monitoring provides numerous advantages in the fabrication of HgCdTe-based infrared devices. Two in situ monitoring techniques are currently being investigated in our laboratory: optical emission spectroscopy (OES) and ellipsometry. OES is ideal for end point detection, for monitoring reactor integrity, and it also provides chemical information. Ellipsometry is a technique useful for the determination of film thickness and surface roughness. Process control can be readily achieved through the implementation of these two in situ measurement techniques. Examples of the use of OES for end point detection during the plasma etching of }fgCdTe and ZnS are discussed. In situ ellips.ometry is being pursued for monitoring the mild plasma etching of bromine/ methanol polished HgCdTe surfaces prior to in situ passivation and insulator deposition. To support the utility of in si.u ellipsoriietry, our initial studies using ex situ ellipsoinetry measurements of plasma etched HgCdTe are highlighted. The advantages of in situ monitoring for multistep vacuum processing, including contamination reduction and improved process control, are presented.
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