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  Anchor Semiconductor, Inc.  
 

Combination of rule and pattern based lithography unfriendly pattern detection in OPC flow

 

 

ABSTRACT
Foundry companies encounter again and again the same or similar lithography unfriendly patterns(Hot-spots)in different designs within the same technology node and across different technology nodes, which eluded design rule check(DRC), but detected again and again in OPC verification step. Since Model-based OPC tool applies OPC on whole-chip design basis, individual hot-spot patterns are treated same as the rest of design patterns, regardless of its severity.

We have developed a methodology to detect those frequently appeared hot-spots in pre-OPC design, as well as post OPC designs to separate them from the rest of designs, which provide the opportunity to treat them differently in early OPC flow. The methodology utilizes the combination of rule based and pattern based detection algorithms. Some hotspot patterns can be detected using rule-based algorithm, which offer the flexibility of detecting similar patterns within pre-defined ranges. However, not all patterns can be detected(or defined)by rules. Thus, a pattern-based approach is developed using defect pattern library concept. The GDS/OASIS format hot-spot patterns can be saved into a defect pattern library. Fast pattern matching algorithm is used to detect hot-spot patterns in a design using the library as a pattern template database. Even though the pattern matching approach lacks the flexibility to detect patterns’ similarity, but it has the capability to detect any patterns as long as a template exists.

The pattern-matching algorithm can be either exact match or a fuzzy match. The rule based and pattern based hot-spot pattern detection algorithms complement each other and offer both speed and flexibility in hot spot pattern detection in pre-OPC and post-OPC designs.

In this paper, we will demonstrate the methodology in our OPC flow and the benefits of such methodology application in production environment for 90nm designs. After the hot spot pattern detection, examples of special treatment to selected hot spot patterns will be shown.

Key words:Optical proximity correction(OPC), hot spot detection, defect pattern library, pattern matching

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