Thickness uniformity of silicon-on-insulator fabricated by plasma immersion ion implantation and ion cut

Plasma immersion ion implantation (PIII) is an economical means to implant a high dose of hydrogen into silicon and when combined with ion cut, has been demonstrated to be a viable technique to fabricate silicon-on-insulator (SOI). However, its success in the industry hinges on the quality of the SOI wafers produced. One of the most important parameters is the thickness uniformity of the SOI film. We have observed that the thickness variation across a 150-mm wafer follows a pattern in which the transferred silicon film is thickest in the center and thinnest near the edge. Alpha-step and SIMS measurements indicate that the lateral nonuniformity is caused by the different penetration depths of hydrogen across the wafer. The experimental results can be explained quantitatively by an oblique incidence model. © 1999 IEEE