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Proceedings Paper

A thick CESL stressed ultra-small (Lg=40-nm) SiGe-channel MOSFET fabricated with 193-nm scanner lithography and TEOS hard mask etching
Author(s): Wen-Shiang Liao; Tung-Hung Chen; Hsin-Hung Lin; Wen-Tung Chang; Tommy Shih; Huan-Chiu Tsen; Lee Chung
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Paper Abstract

A 100Å-thick SiGe (22.5%) channel MOSFET with gate length down to 40nm has been successfully integrated with 14Å nitrided gate oxide as well as a 1200Å high-compressive PECVD ILD-SiNx stressing layer as the contact etching stop layer (CESL) that enhances the PMOS electron mobility with +33% current gain. To achieve a poly-Si gate length target of 400Å (40nm), a 193nm scanner lithography and an aggressive oxide hard mask etching techniques were used. First, a 500Å-thick TEOS hard mask layer was deposited upon the 1500Å-thick poly-Si gate electrode. Second, both 1050Å-thick bottom anti-reflective coating (BARC) and 2650Å-thick photoresist (P/R) were coated and a 193nm scanner lithography tool was used for the gate layout patterning with nominal logic 90nm exposure energy. Then, a deep sub-micron plasma etcher was used for an aggressive P/R and BARC trimming down processing and the TEOS hard mask was subsequently plasma etched in another etching chamber without breaking the plasma etcher’s vacuum. Continuously, the P/R and BARC were removed with a plasma ashing and RCA cleaning. Moreover, the patterned Si-fin capping oxide can be further trimmed down with a diluted HF(aq) solution (DHF) while rendering the RCA cleaning process and the remained TEOS hard mask is still thick enough for the subsequent poly-Si gate main etching. Finally, an ultra narrow poly-Si gate length of 40nm with promising PMOS drive current enhancement can be formed through a second poly-Si etching, which is above the underneath SiGe (22.5%) conduction channel as well as its upper 14Å-thick nitrided gate oxide.

Paper Details

Date Published: 27 March 2007
PDF: 6 pages
Proc. SPIE 6520, Optical Microlithography XX, 65204P (27 March 2007); doi: 10.1117/12.708935
Show Author Affiliations
Wen-Shiang Liao, United Microelectronics Corp. (Taiwan)
Tung-Hung Chen, United Microelectronics Corp. (Taiwan)
Hsin-Hung Lin, United Microelectronics Corp. (Taiwan)
Wen-Tung Chang, United Microelectronics Corp. (Taiwan)
National Chia Tung Univ. (Taiwan)
Tommy Shih, United Microelectronics Corp. (Taiwan)
Huan-Chiu Tsen, United Microelectronics Corp. (Taiwan)
Lee Chung, United Microelectronics Corp. (Taiwan)

Published in SPIE Proceedings Vol. 6520:
Optical Microlithography XX
Donis G. Flagello, Editor(s)

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