Paper
24 July 2002 Challenges of 50-nm gate process in alternating phase shifting lithography
Cheng Yu Fang, Kuei-Chun Hung, Z. H. Huang, Benjamin Szu-Min Lin, Shu-Hao Hsu, Yeong-Song Yen, Paul P.W. Yen, Jiunn-Ren Huang, Hua-Yu Liu
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Abstract
An extended 248nm lithography process with alternating phase-shift masks (PSMs) and etch-trimming techniques has produced 50nm gate critical dimensions (CDs). Well-controlled CD uniformity and line-end edge roughness (LER) are also demonstrated in this work. The primary factor in the improvement of through-pitch proximity bias was phase shifter width. With optimum shifter width, where pitches are greater than 600 nm, a through-pitch proximity bias of less than 10 nm can be obtained. Photoresist also has a significant role in implementing alternating PSMs, requiring high activation energy and suitable thickness. Soft-bake and post-bake temperatures were determined to enlarge the depth-of-focus (DOF). The forbidden pitch effect was enhanced to constrain the common process window after optical proximity correction (OPC) had been implemented. However, proximity bias can be kept constant with changeable diffusion length due to the through-pitch CD profiles, all isolated like. Improvement of through-focus CD at the forbidden pitch was examined by optimizing diffusion length; the common process window can be improved by 25%. All process results, including line-end roughness, DOF, exposure latitude, well-controlled CD uniformity, and through-pitch proximity bias, showed that 248 nm photolithography with alternating phase shifting mask could meet the requirements of 100nm node application.
© (2002) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Cheng Yu Fang, Kuei-Chun Hung, Z. H. Huang, Benjamin Szu-Min Lin, Shu-Hao Hsu, Yeong-Song Yen, Paul P.W. Yen, Jiunn-Ren Huang, and Hua-Yu Liu "Challenges of 50-nm gate process in alternating phase shifting lithography", Proc. SPIE 4690, Advances in Resist Technology and Processing XIX, (24 July 2002); https://doi.org/10.1117/12.474238
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KEYWORDS
Critical dimension metrology

Lithography

Photomasks

Diffusion

Optical proximity correction

Phase shifts

Photoresist materials

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