Silicon Verification of Flare Model & Application to Real Chip for Long Range Proximity Correction
Optical proximity correction (OPC) plays a vital role in the lithography process for critical dimension (CD) control. Flare, or stray light, is an added incoherent background intensity that will detract from lithography system performance, CD control, and process latitude. In this paper, the flare effects on CD variation by changing the total image intensity are discussed. The flare map is obtained by running the flare model on the mask layout. Based on the flare map, flare test patterns are designed and flare test reticle is written. After collecting wafer silicon data with CD SEM, flare model is verified and the flare impacts on the across chip line width variation (ACLV) are presented. With the existence of flare, CD bias across different areas of the cell could be measured. Based on the analysis of flare model and the experiment results, applications on flare correction are discussed by using OPC.
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