The plasma dry cleaning rate of semiconductor process chamber walls can be improved by placing a non-gaseous dry cleaning enhancement material in the position which was occupied by the workpiece during semiconductor processing. The non-gaseous dry cleaning enhancement material is either capable generating dry cleaning reactive species and/or of reducing the consumption of the dry cleaning reactive species generated from the plasma gas feed to the process chamber. When process chamber non-volatile contaminant deposits are removed from plasma process chamber surfaces during plasma dry cleaning by placing a non-gaseous source of reactive-species-generating material within the plasma process chamber, the non-gaseous source of reactive-species-generating material need not be located upon or adjacent the workpiece support platform: however, this location provides excellent cleaning results in typical process chamber designs.