| Summary: | 碩士 === 國立交通大學 === 應用化學系 === 90 === Without changing exposure source, the size of device can be reduced by resolution enhancement techniques (RETs). The application of design of experiment (DOE) can increase the process latitude by optimizing parameters and process settings with no extra cost. The using of optical proximity correction (OPC) can correct the pattern distortion of resist effectively.
This thesis can be divided into three parts. The first part is modification of transmittance control mask (TCM). As the line widths get narrower, in order to avoid the photoresist bridging between two contact holes by fabricating an attenuated area in contact hole on mask, the fabrication is quite difficult. If high transmittance material were used in the entire contact hole area, the difficulty of fabrication will be reduced. Simulation has proved that this modification has a good improvement. The second part, the Taguchi Genichi DOE has been applied by using L9 orthogonal array to study the effects of resist parameters and optical parameters on the 248 nm DUV lithographic process for the 0.07μm isolated lines. By simulation, the optimized resist parameters were found out to be prebake temperature 120℃, prebake time 60 sec, post exposure bake temperature 130℃, post exposure bake time 55 sec and development time 50 sec. The optimized optical parameters were found out to be Quadrupole Off-Axis Illumination (OAI) center sigma equivalent 0.6, radius sigma equivalent 0.22, numerical aperture 0.7, transmittance of attenuated phase-shifting mask (APSM) 29%. The optimized results indicated that depth of focus increased from 0.31μm to 0.46μm；exposure latitude increased from 3.81% to 7.62%. Regarding OPC, the using of scattering bar can correct pattern distortion effectively. The third part, the Taguchi method has been applied by using L9 orthogonal array to study the effects of resist parameters and optical parameters on the 248 nm DUV lithographic process for the 0.13μm dense lines. The optimized resist parameters were found out to be prebake temperature 125℃, prebake time 90 sec, post exposure bake temperature 130℃, post exposure bake time 35 sec and development time 45 sec. The optimized optical parameters were found out to be Annular OAI outer ring sigma equivalent 0.8, ratio of inner ring over outer ring sigma equivalent 2/3, numerical aperture 0.7, transmittance of APSM 25%. The optimized results indicated that depth of focus increased from 0.43μm to 0.77μm；exposure latitude increased from 4.59% to 10.59%. Regarding OPC, the using of feature bias can correct pattern distortion effectively.
12 inches wafer will be coupled with 90 nm linewidth in future, the difficulty of fabrication of narrow linewidth is high, using computer simulation combined with Taguchi DOE could analyze and study various process parameters efficiently and systematically.
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