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3 July 1995 Evaluation of shifter edge shape on attenuated phase-shifting mask
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The influence of edge taper angle and edge roughness on transferred wafer image was investigated by computer simulation for sub-half-micron space and hole patterns on the wafer. The exposure latitude for a 0.3- micrometers space pattern on the wafer is almost unchanged for angles exceeding 60 degrees. The exposure latitude for 0.3-, 0.35-, and 0.4- micrometers hole patterns remains almost unchanged unless the edge roughness exceeds 0.04 micrometers . However, when shifter thickness on the pattern edge decreases 50%, a particularly bad case, and edge roughness of 0.01 micrometers results in 25% degradation of exposure latitude. Taking simulation results into consideration, we optimized the mask manufacturing process using wet etching for CrO-based phase shifters and obtained an edge roughness of approximately 0.01 micrometers and an edge taper angle greater than 60 degrees. Experiment showed that wet-etched mask performance is equivalent to that of the dry-etched mask.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Taro Saito, Hideyuki Jinbo, K. Yano, Seki Suzuki, and Yoshio Tanaka "Evaluation of shifter edge shape on attenuated phase-shifting mask", Proc. SPIE 2512, Photomask and X-Ray Mask Technology II, (3 July 1995);

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