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21 March 2007 OPC to reduce variability of transistor properties
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Scaling toward 65 nm and beyond, process variations are increased and influences both functional yield and parametric yield. The process variations consist of systematic components and random components. Systematic variations are caused by predictable design and process procedures, therefore systematic variations should be removed from process corner model for LSI design. With the effect of scaling, print images on a wafer shows complicated distortion. The method of calculating distorted transistor properties without slicing into individual rectangular transistors has been previously proposed. Using this calculation method, transistor properties with distortion are able to be calculated, reduction of transistor property variations is expected. Transistor property variations caused by layout dependence could be reduced by using OPC with SPICE for each transistor, however, the calculation time of gate length retarget with SPICE is not realistic. Therefore we have investigated approximation for transistor properties using statistics of gate length distribution and layout parameters, and found that parameter fitting by average and &sgr; of gate length distribution of each transistor is useful. According to the results of application to standard cell libraries using OPC with transistor property estimation, we have achieved that our new OPC reduces threshold voltage and drive current variations greatly without increasing throughput. It is difficult to suppress variation about all properties without area penalty, however, property priority required for each transistor is different. Therefore performance improvement of the whole circuit and chip is possible by the argument of priority between manufacturing engineer and circuit designer or using design intents.
© (2007) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Kaoru Koike, Kohichi Nakayama, Kazuhisa Ogawa, and Hidetoshi Ohnuma "OPC to reduce variability of transistor properties", Proc. SPIE 6521, Design for Manufacturability through Design-Process Integration, 65210J (21 March 2007);


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