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17 May 1994 Optimizing distortion for a large-field submicrometer lens
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A large field i-line lens has been developed for submicron IC manufacturing. This lens has a field size of 22 mm X 44 mm (total area of 9.68 cm2), which is the largest field size of any current submicron microlithographic lens. A primary consideration in the development of this lens is its overall distortion, which must be small enough to provide total overlay consistent with submicron design rules. This paper presents distortion characteristics of the Ultratech Stepper Model 2244i lens. Models that can be used to predict the lens distortion and result in minimizing absolute distortion have been developed. The technique used to minimize the lens distortion of the 2244i, along with the effectiveness and the application, also is described. We review the utility of this process for matching new lenses to a customer's existing lenses, and we show how this process supports the mix-and-match of this lens's large field size with the smaller fields of reduction lenses.
© (1994) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Shiow-Hwei Hwang and Bruce J. Ruff "Optimizing distortion for a large-field submicrometer lens", Proc. SPIE 2197, Optical/Laser Microlithography VII, (17 May 1994);


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