Mask defect printability in the spacer patterning process

We studied the mask defect printability for both opaque and clear defects in the spacer patterning process. 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. The opaque defect and the clear defect of the mask, respectively, resulted in an "open-short complex" defect and a short defect in the spacer pattern, The defect size of both the opaque and clear defect became smaller as the process proceeded from the development to the core film etching and the spacer pattern fabrication. The decrease of the mask defect printability during the spacer process is likely to be related to the reduction of the line width roughness (LWR) and to the reduction of mask enhanced factor (MEF). The acceptable mask defect size was also studied from the viewpoint of the defect printability to the spacer pattern for both the opaque and clear defect, and found to be 55-60nm, which was relaxed from that in ITRS2007.