A novel statistically designed tracking technique is described which utilizes multiple exposure systems and photoresists to decompose tool, material, and process contributions to variation in lithography. The application of this technique is described as a means of characterizing an overall lithography process. In one application, the primary source of variation in the photo process was attributed to resists and resist processes rather than related to exposure tool. Process variation in one resist system was tracked unambiguously to changes in developer normality. Finally, results from this work extended previous studies showing that open frame exposure measurements are sensitive measures of photoresist process variation for both conventional and chemically amplified resists.
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