Nano-scale linewidth measurements are performed in semiconductor manufacturing, the data storage industry, and micro-mechanical engineering. It is well known that the interaction of probe and sample affects the measurement accuracy of linewidth measurements performed with atomic force microscopy (AFM). The emergent ultra-sharp carbon nanotube tips provide a new approach to minimizing the distortion of the measured profile caused by interaction with the finite probe tip. However, there is nearly always a significant tilt angle resulting when the nanotube is attached to an ordinary probe. As a result, we can obtain an accurate sidewall image of only one side of the linewidth sample rather than two sides. This somewhat reduces the advantage of using nanotube probes. To solve this problem, a dual image stitching method based on image registration is proposed in this article. After the first image is obtained, which provides an accurate profile of one side of the measured line, we rotate the sample 180° to obtain the second image, which provides an accurate profile of the other side of the line. We keep the sidewall data for the better side of each image and neglect the data taken for the other side of each image. Then, we combine these better two sides to yield a new image for which the linewidth can be calculated.
The continental scaling down of CMOS feature size to 100 nm and below necessitates a characterization technique to resolve high aspect ratio features in the nanoscale regime. This paper reports the use of atomic force microscopy coupled with high aspect ratio multi-walled carbon nanotube scanning probe tip for the purpose of imaging surface profile of photoresists. Multi-walled carbon-nanotube scanning probe tip for the purpose of imaging surface profile of photoresists. Multi-walled carbon-nanotube tips used in this work are 5-10 nm in diameter and about a micron long. Their exceptional mechanical strength and ability to reversibly buckle enable resolution of steep, deep nanometer-scale features. Images of photoresist patterns generated by 257 nm interference lithography as well as 193 nm lithography are presented to demonstrate multi-walled carbon nanotube scanning probe tip for applications in metrology.
Interferometric lithography affords the unique ability to independently control dose, pitch and aerial image contrast during photolithographic exposure. In this report, we describe the use of a deep-UV interferometric lithography exposure tool to study the impact of aerial image contrast on resists imaging properties. A wide range of high resolution resists materials was surveyed, including positive- and negative-tone systems, chemically amplified and conventional diazonaphthoquinone imagining chemistries, and aqueous- and solvent-developed systems. In all cases, resist line- edge roughness was observed to increase as aerial image contrast was decreased, though the precise behavior varied with resist material. Polymer molecular weight was systematically varied with resists materia. Polymer molecular weight was systematically varied in a negative- tone chemically amplified resist formulation. The results indicate that molecular weight is a significant factor influencing the magnitude and type of line-edge roughness at low aerial image contrast.
The systematic substitution of fluorine for hydrogen in mesogenic materials has proved to be of great value for the modification of a wide range of physical properties. This is especially true in the case of ferroelectric liquid crystals in which the fluorine has been strategically introduced into the aromatic core (k), at or near the chiral center (Z) or in the achiral tail (n) in the generic liquid crystal (with X equals O, S and Z equals Me, halogen): H/F(CF2)n(CH2)mOC6H(4 - k)FkCOXPhOCOC*HZR. In this system the fluorine can be introduced in any of these three specific locations, or any combinations thereof, with the intent of enhancing performance such as broadening of the ferroelectric Sc* phase temperature range, enhancement of the magnitude of spontaneous polarization Ps and a variety of more subtle yet important modifications such as viscosity and dielectric and optical anisotropy. The ramifications of the incorporation of fluorine on these physical properties are discussed with a variety of examples.
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