Thermal donor annihilation and defect production in <i>n</i>-type silicon by rapid thermal annealing

Abstract

Thermal donor (TD) introduction and annihilation in magnetic-field-applied Czochralski-grown (100) n-type silicon with an oxygen concentration around 8.5×1017 cm−3 have been studied with deep-level transient spectroscopy (DLTS), capacitance-voltage (C-V), and resistivity measurements. The introduction of TDs has been performed with heat treatment at 450 °C, and the annihilation of TDs has been investigated with rapid thermal annealing (RTA) in the temperature range 600–1080 °C. The change of the resistivity with heat-treatment time at 450 °C corresponds to that of the DLTS signal observed around 55 K, identified with TDs. C-V measurements show the decreasing thermal-donor depth profile with shallower depth. TDs are found to disappear by RTA around 800 °C. However, four electron traps, A1 (Ec −0.18 eV), A2 (Ec −0.25 eV), A3 (Ec −0.36 eV), and A4 (Ec −0.52 eV), are induced by RTA above around 700 °C. These traps are induced only by RTA without thermal donor introduction. The significant feature of these RTA-induced defects shows the spatial distributions across the wafer. Traps A2, A3, and A4 have W-shaped patterns, and a trap A1 has an M-shaped pattern. It is suggested that RTA-induced defects are caused by the thermal stress due to the temperature nonuniformity across the wafer during RTA.