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5 May 2005 Manufacturing-aware design methodology for assist feature correctness
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Sub-resolution assist features (SRAFs) provide an absolutely essential technique for critical dimension (CD) control and process window enhancement in subwavelength lithography. As focus levels change during manufacturing, CDs at a given "legal" pitch can fail to achieve manufacturing tolerances required for adequate yield. Furthermore, adoption of off-axis illumination (OAI) and SRAF techniques to enhance resolution at minimum pitch worsens printability of patterns at other pitches. Our previous work [Gupta et al.] described a novel dynamic programming-based technique for Assist-Feature Correctness (AFCorr) to account for interactions within a cell row. We now extend the AFCorr methodology to handle vertical interactions of field polys between adjacent cell rows in the detailed placement of standard-cell designs. Pattern bridge between field poly geometries becomes a major reason for yield degradation even though CD variation of gates determines circuit performance. In this paper, AFCorr is validated in all possible horizontal (H-) and vertical (V-) interactions of polysilicon geometries in the layout. For benchmark designs, forbidden pitch count between polysilicon shapes of neighboring cells is reduced by 89%-100% in 130nm and 93%-100% in 90nm. Edge placement error (EPE) count is also reduced by 80%-98% in 130nm and 83%-100% in 90nm. AFCorr facilitates additional SRAF insertion by up to 7.4% for 130nm and 7.9% for 90nm. In addition, AFCorr provides substantial improvement in CD control with negligible timing, area, or CPU overhead. The advantages of AFCorr are expected to increase in future technology nodes.
© (2005) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Puneet Gupta, Andrew B. Kahng, and Chul-Hong Park "Manufacturing-aware design methodology for assist feature correctness", Proc. SPIE 5756, Design and Process Integration for Microelectronic Manufacturing III, (5 May 2005);

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