7 November 1983 Edge Sharpening, Contrast Enhancement, And Feature Dependent Amplification In Inorganic Resist - A Simulation Study
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Computer simulation of the photodoping and lateral diffusion of silver during exposure is used to explore the theoretical potential of inorganic resists and to explore the extent to which it is realized in the Ge-Se resist system. The resist exposure is modeled as photodoping, silver into the substrate at the bottom of a bleachable sensitized layer. The silver concentration is assumed to be uniform vertically throughout the layer and allowed to diffuse laterally. The amount of photo-doping is proportional to the product of the intensity of light reaching the bottom of the sensitized layer and the local silver concentration. The layer is assumed to have a bleachable absorption proportional to the silver concentration , a nonbleachable absorption and a bleaching rate coefficient. A FORTRAN algorithm for solving the resulting coupled differential equations has been developed for use with the SAMPLE program. Both dynamic bleaching (hole burning) and lateral diffusion can lead to a sharper edge and/or higher contrast in the photodoped silver concentration than those in the incident exposure aerial image. For the 100A thick Ge-Se system at 0.75 urn features on the GCA DSW4800 stepper, the diffusion length is two times larger than the feature size, so that the contrast is equal to that of the aerial image at any exposure time. For large features with large transition region between the clear and dark fields contrast enhancement can be obtained using thick resists ($>100 A sup 0$) at the expanse of longer exposure time. For Ge-Se the lateral diffusion combined with photodoping saturation allow a feature dependent amplification of the relative silver concentrations for various feature sizes. This together, with the high contrast development process [1] allow inorganic resist to image well at low contrast exposure.
© (1983) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Wingyu Leung, Wingyu Leung, Andrew R. Neureuther, Andrew R. Neureuther, William G. Oldham, William G. Oldham, "Edge Sharpening, Contrast Enhancement, And Feature Dependent Amplification In Inorganic Resist - A Simulation Study", Proc. SPIE 0394, Optical Microlithography II: Technology for the 1980s, (7 November 1983); doi: 10.1117/12.935131; https://doi.org/10.1117/12.935131


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