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7 July 1997 Scanning array lens lithography for large-area applications
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A new optical system has recently been developed for large area lithography applications. The new optical system is referred to as scanning array lens lithography (SALLY) and is based on the well-known Wynne-Dyson 1:1 projection lens configuration that has found widespread use in the IC, thin- film head and micromachining industries. The array lens is designed to project essentially a single elongated field that can be extended to span the width of any substrate. This enables a substrate to be exposed in a single scanning motion. The array lens is composed of multiple, compact catadioptric lens relays having trapezoidal shaped image fields that are positioned in an alternating and overlapping fashion. The resulting imaging capability is comparable to that of a single very large well-corrected lens. Features exposed in the transition between separate fields exhibit no visible variations in their structures. This paper describes the system configuration and test results for a three-field prototype SALLY system composed of lens relays with a numerical aperture (NA) of 0.10. This NA was selected to provide a useful combination of resolution, depth-of-focus (DOF) and exposure irradiance for large area and thick resist applications. SEM results from field-to-field measurements demonstrate that a seamless transition between separate image fields can be achieved. Resolution of equal line/space patterns down to 2.3 micrometer has been attained. In addition, thick resist imagery showing thickness to linewidth aspect ratios of greater than 8.5:1, in 33 micrometer thick resist is shown.
© (1997) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Lawrence C. Wang, David A. Markle, and Raymond J. Ellis "Scanning array lens lithography for large-area applications", Proc. SPIE 3048, Emerging Lithographic Technologies, (7 July 1997);

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