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14 December 2009 The effect of UPW quality on photolithography defect
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Proceedings Volume 7520, Lithography Asia 2009; 75202V (2009)
Event: SPIE Lithography Asia, 2009, Taipei, Taiwan
Photolithography resist process consists of priming, resist coating, post-apply bake, exposure, post-exposure bake develop, and post bake; advanced RETs and immersion photolithography has more critical resist process steps. Materials used in the resist process require the utmost in cleanliness, especially coating & develop process. In photolithography, De-Ionized Water (DIW) or Ultra Pure Water (UPW) is used during resist developing process as the pre-wet and rinsing material. UPW is supplied by a centralized auto supply system in a semiconductor fabrication; the UPW is controlled for temperature, pH, resistivity, TOC, ions, and etc. State of the art semiconductor design continues to shrink; defect control becomes essential for high yields in semiconductor fabrication. In this paper, effect of UPW quality on resist process defect is revealed. Low resistivity DIW used in resist developing process generates residue defects, which created killing block etch defect after the subsequent etching process. Different measurements for DIW quality are demonstrated; water pH, conductivity, and Total Organic Carbon (TOC) in this case reflected the quality issue of UPW. Detail study on the residue defect and the cause-and-effect with UPW's quality is shown and discussed; the hypothesis is explained with experimental results. High quality UPW is required to eliminate the residue defect, hence minimal defective wafer is obtained. Additionally, resist developing process optimization to improve process robustness is also important.
© (2009) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Wah Hoo Ng, Siew Ing Yet, and Chu Yaw Liau "The effect of UPW quality on photolithography defect", Proc. SPIE 7520, Lithography Asia 2009, 75202V (14 December 2009);

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