Effect of rapid thermal annealing on bulk micro-defects and plastic deformation in silicon during high temperature processing

We studied how rapid thermal annealing (RTA) affects bulk micro-defects (BMDs) and plastic deformation in Si wafers processed at high temperatures. BMDs caused by oxygen precipitation at 1200 °C were investigated in Si wafers as a function of annealing time with and without RTA and pre-annealing. Only the pre-annealed RTA wafer revealed an average BMD size of ~50 nm after annealing at 800 °C for 2 h and subsequently at 1000 °C for 4 h, and such wafers retained BMDs after annealing at 1200 °C for 500 min. The relationship between BMDs and plastic deformation was investigated for Si wafers subjected to RTA at various temperatures. Dislocations were generated and propagated after the simulated CMOS heat treatment as RTA temperature increased because of the low dislocation pinning effect produced by the reduction in residual oxygen while precipitated oxygen concentration increased. Incident angle deviation in the rocking curve indicated a high degree of plastic deformation caused by high RTA temperature after performing a realistic device fabrication process. We propose that a combination of RTA and a pre-annealing process can improve the internal gettering efficiency during high temperature processing, which controls BMDs. This would balance the residual oxygen and preventing plastic deformation.