Method of Designing Phase-Shifting Masks Utilizing a Compactor

概要

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A new method is proposed for designing Levenson-type phase-shifting masks. In this method, phases are assigned in an intermediate layout, and then the intermediate layout is converted to a final layout. In practice,the intermediate layout is a symbolic layout, and the symbolic layout is converted to a mask layout by a compactor. According to the strategy, no conflict spots arise during the operation, which greatly improves design efficiency. This design method is applicable to random patterns in a memory peripheral circuit and in microcomputer chips. As a result of application to the peripheral circuit of dynamic random access memory (DRAM), about 16% shrinkage of the mask area was obtained, compared with a conventional mask. As for a microcomputer chip, 12% shrinkage of mask area was obtained under the condition of 50% shrinkage of aluminum-wire spacing. Together with the interactive method reported before, which is applicable to a memory core circuit, the design of the Levenson-type masks for standard LSIs is totally covered.
社団法人応用物理学会の論文
1994-12-30