发明授权
US07132340B2 Application of post-pattern resist trim for reducing pocket-shadowing in SRAMs
有权
用于减少SRAM中的口袋阴影的后图案抗蚀剂修整的应用
- 专利标题: Application of post-pattern resist trim for reducing pocket-shadowing in SRAMs
- 专利标题(中): 用于减少SRAM中的口袋阴影的后图案抗蚀剂修整的应用
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申请号: US11018602申请日: 2004-12-21
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公开(公告)号: US07132340B2公开(公告)日: 2006-11-07
- 发明人: Kayvan Sadra , Theodore W. Houston
- 申请人: Kayvan Sadra , Theodore W. Houston
- 申请人地址: US TX Dallas
- 专利权人: Texas Instruments Incorporated
- 当前专利权人: Texas Instruments Incorporated
- 当前专利权人地址: US TX Dallas
- 代理商 Peter K. McLarty; W. James Brady, III; Frederick J. Telecky, Jr.
- 主分类号: H01L21/8238
- IPC分类号: H01L21/8238 ; H01L21/336
摘要:
Methods (600, 700) are disclosed for minimizing the effect of pocket shadowing in the fabrication of an angled pocket implant (32) extending underlying a gate region (21) of a transistor (10), particularly in SRAM devices (400). The pocket shadowing is minimized by initially forming a relatively thick resist layer (810) overlying the semiconductor device (800), then the resist layer thickness (810y) is reduced (trimmed) to a reduced thickness (860y) by using a subsequent post-development dry or wet resist-reduction etch process (630, 730). The etch process (630, 730) also increases corner rounding (860r), thereby reducing pocket shadowing of the angled implant from nearby features or the resist (228, 328, 860). The pocket shadow reduction may be accomplished by first forming (610, 710) the relatively thick resist layer (810) overlying the semiconductor device (400, 800). The resist layer (860) is then wet and/or dry etched (630, 730) to trim the resist thickness (860y) and to round the corners (860r) of the resist (442, 860). In combination, these changes reduce shadowing of angled implants from nearby structures and resist edges. The method may further comprise a first implant (720) (e.g., an LDD implant) before the resist etch trim (730), and a second angled pocket implant (740) after the etch trim (730) to permit individually optimizing the resist thickness and CD for each implant. Thus, only one lithography step is required, while cross diffusion of the LDD implant is mitigated. Transistors (443 and 446, 448, or 830 and 840) formed in this manner may yield improved performance when incorporated into SRAM (400, 800) since the probability that such transistors will be more closely matched is increased.
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