Effect of External Stress at Annealing on Microstructure of Silicon Co-Implanted with Hydrogen and Helium

摘要

The effect of stress, exerted by enhanced hydrostatic pressure (HP, up to 1.1 GPa) of ambient gas during thermal treatment at up to 1270 K (HT), on the micro structure and gettering activity of Czochralski silicon co-implanted with H_2~+ and He~+ (Cz-Si:H,He;H_2~+ energy, E_H = 135 KeV, H dose, D_H = 5 * l0~(16) cm~(-2); E_(He) = 150 keV, D_(He) = 5 * lO~(16) cm~(-2)) was investigated by SIMS, TEM, ;X-ray and photoluminescence methods. The HT - HP treatment of Cz-Si:H,He at <920 K results in formation of H_2/He filled cavities and bubbles; mainly dislocations are created at ≥1070 K. The concentration of defects decreases with HP. Contrary to the case of HT-HP treated Cz-Si:H, hydrogen out-diffusion from Cz-Si:H,He is more pronounced at HP than under 10~5 Pa. Gettering of oxygen in the damaged areas at ≤780 K-HP is suppressed while it does not depend on HP for the treatments done at ≥1070 K, Qualitative explanation of the HT-HP effect on the Cz-Si:H,He microstructure demands future research. Restrained out-diffusion of He atoms under HP, affecting in turn creation of the H-Si bonds and so the rate of hydrogen out-diffusion, seems to be responsible in part for observed phenomena.