Paper
24 July 1996 Resolution enhancement with thin Cr for chrome mask making
Byung-Cheol Cha, Seong-Woon Choi, Jin-Min Kim, Hanku Cho, Jung-Min Sohn
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Abstract
The main issue for fabricating a conventional Cr Mask with e-beam exposure system is a resolution limitation. Required minimum Critical Dimension (CD) goes down to below 1.0 μm on 4 X reticle, sometimes down to below 0.5 μm for OPC pattern. The resist which widely used in E-beam lithography is positive tone PBS. PBS has used in wet chrome etching process with spin spray or dip methods, due to its lack of resistance to dry etch durability. However, the isotropic process of wet chrome etching results in undercutting of the chrome. Thus, undercut causes the differences of CD between after development and final mask image. The purpose of this study is to decrease undercutting so that CD error can be minimized and a lot of rooms for overdevelopment margin can be obtained. CD linearity in case of below 1.0 μm was also investigated in detail. For this study, the chrome thickness coated on 6 x 6 x 250 mil PBS chrome plates was reduced. As a result of our study, we found that overdevelopment is marginal for the same final CD when using the thinner Cr, due to undercutting reduced. Good CD uniformity has been also achieved with good CD linearity.
© (1996) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Byung-Cheol Cha, Seong-Woon Choi, Jin-Min Kim, Hanku Cho, and Jung-Min Sohn "Resolution enhancement with thin Cr for chrome mask making", Proc. SPIE 2793, Photomask and X-Ray Mask Technology III, (24 July 1996); https://doi.org/10.1117/12.245205
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KEYWORDS
Critical dimension metrology

Chromium

Etching

Wet etching

Photomasks

Dry etching

Mask making

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