Wilhelmus Peter Martinus Nijssen

ImRe, BIM and SUPER using patternwise esterification

Abstract Patternwise esterification of diazonaphthoquinone - novolak based photoresists was used for three advanced photolithographic procedures namely ImRe (Image Reversal), BIM (Built In Mask) and SUPER (SUbmicron Positively dry Etch Resist). With all three techniques 0.6 μm patterns with vertical side walls could be obtained using 405 nm UV light and a 0.30 NA lens. This corresponds with a k-factor of 0.44, which is well beyond the Rayleigh limit (k = 0.61).

Built in mask (BIM): a new way to a submicron process with high resolution and good latitude

Abstract The performance of the Image Reversal (ImRe) process can be improved considerably by formation of a dye in the patternwise irradiated, insolubilized, areas. The dye is generated during the reversal bake and acts as a (built in) mask during the blanket exposure. The resulting intensity distribution is self-aligned to the intensity distribution of the first exposure and thus leads to a better defined mask edge in the latent image. Simulation results obtained with the newly developed program SLIM (Simulation of Latent Image Manipulation) and some chemical routes for dye formation are presented.

High resolution optical lithography by formation of a Built On Mask (BOM)

Abstract By means of a U.V. induced shift in absorption from 360 to 435 nm an image is formed in a photosensitive layers on top of a positive photoresist. Upon heating this image becomes fixed. The resulting mask, which we call a Built On Mask (B.O.M.), is transferred into the photoresist by means of a flood exposure. Then the top layer is stripped and the photoresist developed. A positive resist image results when the flood exposure is done with 365 nm and a negative image results with a 435 nm flood exposure. Experiments with the BOM system show a resolution capability which lies below 0.8 μm and also a large process latitude.