Pressure control for reduced microbubble formation

摘要

Microbubbles in leading-edge photoresist materials create a challenge to the demanding yield requirements of today's shrinking circuit designs. When microbubbles are dispensed onto a wafer surface, they can act as an additional lens in the exposure path, ultimately distorting the pattern and affecting yield. Proper filter selection, filter priming, and dispense settings chosen during process startup are critical to reducing microbubbles, but certain chemistries can continue to cause problems even if the process has been optimized.rnThis paper presents the results of applying a small amount of positive pressure on the chemistry before the dispense nozzle to reduce microbubbles in top anti-reflective coating (TARC). A two-stage technology dispense system was utilized to adjust the pressure on the chemistry in the dispense line while an in-line optical particle counter monitored the microbubbles generated during the dispense process.