Quantifying proximity and related effects in advanced wafer processes

Proximity effect correction presumes that a significant proportion of CD variations observed in wafer lithography and processes can be systematically predicted from calculations made on a pattern layout prior to fabrication. Total shape variations include a portion that repeats from chip-to-chip and wafer-to-wafer, and a randomly varying portion. Repeating effects can be compensated by modifying feature shapes on the mask pattern. The project described in this report is a study to characterize the systematic shape distortions in an experimental 0.25 micrometers process. Analyses of variation are made to quantify dependencies on specific variation sources. Two-dimensional 'behavior models,' derived from characterization data measured from processed wafers, can be used to compute shape corrections for arbitrary pattern layouts. This project was undertaken in collaboration with the Hewlett Packard Research Laboratories, Palo Alto, CA.