PMJ' 99 panel discussion review: OPC mask technology for KrF lithography

Optical proximity effect correction (OPC) now is a prerequisite technique to improve common process windows of the present optical lithography process. It will be also applied to 0.13 micrometer device processes. Although the technology is now widely used, there are still issues to be solved in terms of choice of OPC methods, pattern fidelity specs, software/data processing limitations, mask manufacturing equipments and manufacturing yields with costs. Photomask Japan '99 Symposium (PMJ '99) had a panel discussion this year covering such issues. For 0.13 micrometer generation, critical dimension (CD) accuracy of plus or minus 4 nm on wafer is given for error budget derived from masks, which OPC masks must also achieve. Mask defects with a size of 70 nm must be repaired, which also requires mask repair accuracy of OPC geometry copy features with high performance. As OPC is sometimes applied to the corner part of figure shapes, it is also required to clarify CD specifications for such portions depending on desired pattern layouts. A mask process with zero defects will also be required as a countermeasure of such mask making difficulty. As a consensus, it is also proposed that acceleration of collaboration between device makers, equipment/software makers and mask shops is much required.