Comparison of arsenic diffusion in Si1−xGex formed by epitaxy and Ge+ implantation

Abstract

A comparison is made of arsenic diffusion in Si 0.95 Ge 0.05 produced by epitaxy and ion beam synthesis using a 2ϫ10 16 cm Ϫ2 Ge ϩ implant into silicon. The arsenic diffusion depth at 1025°C in the Si 0.95 Ge 0.05 epitaxy sample is enhanced by a factor of 1.26 compared with a similar Si control sample and by a factor of 1.30 in the ion beam synthesized sample. The arsenic diffusion in the Si 0.95 Ge 0.05 epitaxy sample is modeled by increasing the arsenic diffusion coefficient from the Si value of 1.92ϫ10 Ϫ15 to 5.15ϫ10 Ϫ15 cm 2 s Ϫ1 , and in the ion beam synthesized sample by using the same diffusion coefficient of 5.15ϫ10 Ϫ15 cm 2 s Ϫ1 and increasing the ''plus one'' factor in the transient enhanced diffusion model from 0.01 to 1.5. Arsenic diffusion in a silicon sample implanted with 2ϫ10 15 cm Ϫ2 Si ϩ can be modeled using the same plus one factor of 1.5, thereby demonstrating the consistency of the modeling.

Dopant diffusion modeling for heteroepitaxial SiGe∕Si devices

“…However, subsequent experiments challenged this notion, as intrinsic dopant concentrations also showed similar enhancement/retardation in SiGe. 3,[6][7][8][9][10][12][13][14][15] This can be explained only by a "chemical effect." 7 However, subsequent experiments on relaxed SiGe also found similar changes in dopant diffusion with germanium.…”