Hi, When purchasing an oxygen plasma cleaner/etcher, what's the optimal frequency? I've seen units available with 50 kHz, 100 kHz, 13.56 MHz, and 2.45 GHz. I primarily intend to use it to remove photoresist (AZ P4620) from 2" diameter Si wafers containing Cu and Au structures. I may also want to use it in the future for parylene removal and Si3N4 etching (using CF4 + oxygen). Any comments on the best frequency? Some vendors have told me that 13.56 MHz is best for PR removal but the yieldengineering web site recommends 50 kHz. Also, is electrode shape (parallel plates vs. circular coil) critically important? Thanks. Jeff Prof. Jeffrey P. Wolinski Department of Physics Grove City College, Faculty Box 3137 100 Campus Drive Grove City, PA 16127-2104 Voice: 724-458-2201 Fax: 724-458-2181