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12 June 2003 Characterization of resist flow process for the improvement of contact hole CD uniformity
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We can print contact hole pattern beyond the optical resolution limit using resist flow process. But CD uniformity should be improved for its masse implementation because CD uniformity gets worser as shrink bias gets larger in resist flow process. For example, contact hole size of wafer edge region is larger by the amount of about 20nm than that of wafer center region. Contact hole CD uniformity depends on uniformity of wafer temperature to which bake oven temperature uniformity and atmosphere temperature uniformity surrounding the wafer in bake oven can affect. The air and exhaust have large effect on the temperature uniformity of atmosphere surrounding the wafer. And mechanical structure of bake oven has an influence on wafer temperature uniformity. So we tested CD uniformity according to types of middle cover in bake oven. We also investigated CD uniformity according to resist inherent characteristics concerning resist flow rate. We optimized resist flow process using two step flow system, which improves wafer CD uniformity by amount of 30% compared to one step resist flow process and considering resist thickness dependency. Device characteristics of chain resistance uniformity was enhanced by improving contact hole CD uniformity.
© (2003) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Cha-Won Koh, Dong-Ho Lee, Myoung-Soo Kim, Sung-Nam Park, and Won-Taik Kwon "Characterization of resist flow process for the improvement of contact hole CD uniformity", Proc. SPIE 5039, Advances in Resist Technology and Processing XX, (12 June 2003);

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