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Masaru SASAGO Takahiro MATSUO Kazuhiro YAMASHITA Masayuki ENDO Kouji MATSUOKA Taichi KOIZUMI Akiko KATSUYAMA Noboru NOMURA
New critical-dimension controlling technique of off-axis illumination for aperiodic patterns has been developed. By means of arranging not-imaging additional pattern near 0.25 micron isolated patterns, the depth of focus of an isolated pattern was improved as well as the periodic patterns. Simulation and experimental results were verified on a 0.48 numerical-aperture, KrF excimer laser stepper. Using new deep-ultra-violet hardening technique for chemically amplified positive resist, the critical dimension loss of resist pattern was prevented. 0.25 micron design rule pattern was obtained with excellent mask linearity without critical-dimension-loss. The combination techniques are achieved quarter micron design rule complex circuit pattern layouts.