His suggestion is to adopt phase-compliant design rules, but to delay phase assignment until final verification. This could be avoided, he said, if a target layer can be used as a reference. It can effectively double the resolution of an optical lithography system, but not without cost, he noted. Designers need to know it intimately. Heng said that AltPSM can have a density impact of up to 6 percent and a resource impact of 10 to 20 percent.
Spacing conflicts can also be an issue.
There are several approaches to resolve conflicts. One involves the use of phase-breaking blocks to break unwanted interactions between phase shapes. Another is increasing the width of critical features, and a third is increasing spacing between critical features. We need a well-thought out AltPSM methodology and a new set of tools to handle it. All rights reserved.