8 August 1993 Comparison of various phase-shift strategies and application to 0.35-μm ASIC designs
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Phase shifting masks for real circuits have been investigated extensively only for DRAMs. In this paper, we report on the applicability of i-line phase shifting lithography to the production of application specific ICs (ASICs). The performance of several phase shift strategies is compared, using an i-line stepper with a numerical aperture of 0.48. Data preparation and mask technology considerations are taken into account. Emphasis is placed on the two most critical levels: poly gate and contact window. Results on poly topography are shown. For the poly level, the frequency doubling alternating shifter strategy in combination with a positive resist seems to be capable of printing features down to 0.35 micrometers CD, but the development of automatic phase shift level generation software is still in a preliminary phase. Edge contrast enhancement strategies in combination with a negative resist are considerably simpler, in particular the halftone PSM strategy. These strategies are also very useful in combination with a positive resist for the contact level, where a doubling of the process latitudes was obtained.
© (1993) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Kurt G. Ronse, Kurt G. Ronse, Rik M. Jonckheere, Rik M. Jonckheere, Casper A. H. Juffermans, Casper A. H. Juffermans, Luc Van den Hove, Luc Van den Hove, } "Comparison of various phase-shift strategies and application to 0.35-μm ASIC designs", Proc. SPIE 1927, Optical/Laser Microlithography, (8 August 1993); doi: 10.1117/12.150416; https://doi.org/10.1117/12.150416

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