Mask defect specification in the spacer patterning process by using a fail-bit-map analysis

We obtained the acceptable mask defect size for both opaque and clear defects in the spacer patterning process using the fail-bit-map analysis and a mask with programmed defects. The spacer patterning process consists of the development of photoresist film, the etching of the core film using the photoresist pattern as the etching mask, the deposition of a spacer film on both sides of the core film pattern, and the removal of the core film. The pattern pitch of the spacer film becomes half that of the photoresist. Both the opaque defect and the clear defect of the mask resulted in a short defect in the spacer pattern. From the fail-bit-map analysis, the acceptable mask defect size for opaque and clear defects was found to be 80nm and 120nm, respectively, which could be relaxed from that in ITRS2008. The difference of the acceptable mask defect size for opaque and clear defects comes from the difference of the defect printability at the resist development.