Extending optical lithography using image reversal processing.
01 January 1987
A commercial image reversal process was evaluated for extending optical lithography resolution. This evaluation uncovered severe uniformity problems using the manufacturer's equipment and suggested process. Results from this study were used to develop a temperature controlled image reversal process which minimized the thermal degradation of the sensitizer in the photoresist and improved wafer to wafer and batch to batch uniformity. Optimization of this modified process demonstrated that the resolution capabilities of GCA6300 steppers can be extended down to 0.625micron linear features with a 2micron focal range on flat oxide wafers. This corresponds to a 30% resolution enhancement using the Tropel 52035G lens employed in this study.