Method of problem solving to diagnose high particle failures due to unique rotation stopping position: CFM: Contamination free manufacturing
Particle defects in the form of foreign material (FM) are a common occurrence in semiconductor manufacturing. This work discusses the strategies used to detect the source of FM particles in a room temperature oxide furnace. FM particles were measured during the 215 Å oxide recipe qualification and showed counts as high 603 particles, exceeding the limit of 130 particles. Common sources of FM particles such as hardware contamination and process recipe conditions were ruled out as the root cause. It was discovered that the rotation stop position of the boat during deposition for the 215 Å recipe put the pedestal alignment pin (attached to the elevator) in front of the backfill N2 injector during the backfill sequence of the recipe. The high flow of 30 slm during the backfill caused the pin to vibrate and produce particles. The probability of stopping at this position for a given recipe is 1 out of 360. The final solution was to make all recipes stop at a home position to guarantee the pin does not stop in front of the N2 injector.