[19a-Z29-1~9] 15.7 Crystal characterization, impurities and crystal defects

[19a-Z29-7] Quality of silicon substrate and point defects (5) CiO2i and NN, CO, NO, OO ring

〇Naohisa Inoue¹, Shuichi Kawamata¹, Shuichi Okuda¹ (1.Osaka Pref. Univ.)

Keywords:silicon crystal, impurity, infrared absorption

Nitrogen in silicon mainly forms Si-N_i-Si-N_i ring. Electron irradiation induced C_iO_i which is used for the lifetime control in the power devices, NO forming shallow thermal donor, and OO (O_2i) forming the core structure of thermal double donor, are the replacement of N_i in the same ring. Moreover these 4 members attract the oxygen by the heat treatment at nearly equal temperature, and their local vibration modes are infrared active. As all of them play important role in the defect formation, it is necessary to reveal their behavior. However, as their concentration is low, it is difficult to analyze as an individual. It is helpful that the information obtained on one member is readily transferred to the others. Here, the case of C_iO_2i whose IR peak has been observed recently at 1020 cm^-1 is shown. The C_iO_2i absorption at 1020 cm^-1 in the electron irradiated and annealed CZ silicon samples was measured. Oxygen becomes active above 350 ^oC. Parallel reactions occur and compete as, (1) C_iO_i+VO=C_sO₂, (2) C_iO_i+VO=C_sO+O, (3) VO+O=VO₂. The following reaction takes place mainly above 400 ^oC and competes with the above reaction (4) C_iO_i+O=C_iO_2i.