8 November 2005 Characteristics of RIE lag and pattern density effect in alternating aperture phase shift masks
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Abstract
As the feature size decreases to 90nm and 65nm, the role of phase shift mask as a RET method becomes more and more important. Although alternating PSM has been one of the possible methods to improve the resolution, however, the difficulty of mask manufacturing prevent us from adopting the technology. One of the main issues is microloading effect including RIE lag, pattern density effect that cause especially the imbalance of phase shifting due to the etch depth difference in the patterns with different CD size and different pitch as the feature size downs to subhalf micron. This leads to the space CD difference with the DOF variation in the wafer image. In this paper, characteristics of RIE lag and other phenomenon were evaluated with the DOE method that included such parameters: source power, bias power and pressure. Etch depth difference was confirmed with AFM measurement and calculated to phase shift angle. Results were analyzed with statistical method and major effects and interaction effects were found.
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Byung-Soo Chang, Yoon-Young Chang, Hyun-Suk Bang, In-Soo Lee, Lee-Ju Kim, Chang-Nam Ahn, Hong-Suk Kim, "Characteristics of RIE lag and pattern density effect in alternating aperture phase shift masks", Proc. SPIE 5992, 25th Annual BACUS Symposium on Photomask Technology, 59923Q (8 November 2005); doi: 10.1117/12.632022; https://doi.org/10.1117/12.632022
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