Megasonic cleaning: A new cleaning and drying system for use in semiconductor processing

A compact system for cleaning wafers in all stages of device manufacture has been developed which uses high frequency (0.8 to 1 MHZ) ultrasonic energy (hence, the term “Megasonic”) and a standard chemical solution which is not heated. The patented process effectively removes particles down to approximately 0.3 ym diameter simultaneously from the front and back surfaces, thin organic films, and many ionic impurities. After a brief water rinse, the wafers are dried in a hot air stream. The total cycle time is approximately 15 minutes, and at least 100 wafers can be cleaned in quartz or plastic carriers at the same time and without the need for loading or unloading. Megasonic cleaning has been applied to silicon wafers, ceramics, and photomasks, and has been used for photo- Paper presented at 20th Annual Electronic Materials Conference, University of California at Santa Barbara, CA, June 30, 1978.