PLASMA IMMERSION ION-IMPLANTATION - THE ROLE OF DIFFUSION

Plasma immersion ion implantation (PI3) can be considered as a hybrid implantation/diffusion technique based on a low pressure r.f. glow discharge. The technology has been moved from small glass vessels to a moderately sized stainless steel chamber. Significant improvements in surface hardness have been obtained for a range of tool steels following treatment at temperatures above 300-degrees-C. The performance of the treated layer is strongly influenced by the nitrides which form during processing. The formation of nitrides has been found to be sensitive to plasma and metallurgical conditions. Direct heating of components in the r.f. plasma has shown that in some cases a purely diffusion treatment may be possible. The factors which govern the extent to which diffusion occurs are explored. The continuous low energy ion bombardment of the target and the excitation of metastable species in the r.f. plasma are considered to be significant for the PI3 process.