CHAMBER WALL CLEANING IN A REACTIVE ECR PLASMA

The basic properties of the chamber wall cleaning in a reactive electr on cyclotron resonance (ECR) plasma have been investigated using poly- Si wafers on the wall, to which a radio-frequency (RF) surface voltage was applied externally. The influence of the cleaning upon the proces sing plasma was also measured by a Langmuir probe. To keep the wall co ndition clean during the plasma processing, it was found that the rati o of cleaning on-time to off-time was an important factor as well as t he potential difference between the plasma and the wall surface. The m ethod of chamber wall cleaning proposed here was quite effective for k eeping the initial wall condition constant without influencing the pla sma parameters in the region of the processing too much. (C) 1998 Else vier Science S.A.