The fabrication of high density VLSI circuits has placed increased demands upon the pattern integrity of photoresist materials. The thermal and chemical effects of high current ion implantation and plasma etching, for example, have led resist manufacturers to formulate durable materials which will withstand harsh processing environments. However, this stability is frequently the cause of difficulties in resist mask removal following such process steps. This work reviews some of the chemical effects which new fabrication technologies have upon polymeric materials and the result of these effects on removal techniques. An afterglow system is presented which utilizes a high fluence of atomic oxygen to oxidize, and hence remove by volatile product formation, these durable and often denatured carbonaceous masking materials. Removal rates up to 6 pm per minute have been achieved. Denatured materials as produced by high current P+ ion implantation, resulting in a dose of 2.5E16 atoms/cm2, have been typically removed at a rate of 1pm per minute. Further, the high flux of atomic oxygen necessary to achieve such rates is produced away from the device structures being processed. Flatband voltage shifts, of MOS struc-tures, induced by processing in this manner are typically less than 0.1 volt, whereas shifts of 1 to 4 volts were obtained by processing in an rf parallel plate plasma system in which the wafer is directly exposed to the oxygen generating region.