Patterning 0.1-μm device by using hybrid PSM

Abstract

Phase shifting mask (PSM) is a method widely known that can enhance optical resolution. Previous work has shown that attenuated PSM with off axis illumination and dark field alternating PSM with double exposure are the two most prominent methods. Both have been shown to print pattern smaller than 0.1 micrometer using KrF. However, using this technique in manufacturing can run into issues on unacceptable overlay error, stronger proximity effect, highly complicated layout, and with much lower wafer printing throughput. In this paper, we introduce a hybrid PSM design and we have characterized the performance by using both simulation and actual wafer data. Our approach is to combine alternating and attenuated PSM into one mask design. For mask making, we have elected to use a high transmission, phase shifting material that coupled with quartz etch process. Several feature types we studied. Of those, poly-gate pattern for both ASIC and DRAM were demonstrated. Data preparation and mask making technology have both been taken into consideration in our analysis. By using this hybrid PSM, sub-0.1 micrometer pattern could be printed with single KrF exposure and with much reduced layout complexity.