Status and Needs of In-Situ Real-time Process Particle Detection

Particle defects play a major role in yield losses in semiconductor device fabrication. It is generally acknowledged that about 50 percent of all yield losses are due to particles. Processing of devices with 0.35 to 0.5 μm minimum feature sizes will exacerbate the effects of particles due to the large relative abundance of submicron particles. The cleanroom is no longer the major particle contributor because current state-of-the-art cleanrooms have less than 10 particles (<0.5 μm) per cubic foot. Particles in processing equipment now play the dominant role in wafer contamination. An analysis of the status and needs of particle detection techniques for semiconductor processing equipment and processes clearly shows that they are inadequate to meet the requirements of the next generation of devices. Detection limits must be improved both in terms of particle diameter and in the number of particles on a wafer. An experimental laser particle counter was fabricated and used to show that such a detector would be extremely useful for in-vacuum realtime particle detection. Experimental studies on wafer surface measurements show that current wafer surface scanning techniques cannot provide the level of detection needed for future devices. Ideas for a new generation of particle detection equipment are presented.