Photoluminescence Mechanisms in Si~+-Implanted Dry SiO_2 Films after Rapid Thermal Annealing at Dissociation Temperature of a-SiO_2 Phase Variance

摘要

Photoluminescence (PL) mechanisms in Si~+-implanted dry SiO_2 films after rapid thermal annealing (RTA) at the dissociation temperature of a-SiO_2 phase variance are further investigated. Two PL mechanisms are found in Si~+-implanted 100-nm-thick dry SiO_2 films after RTA at 1050℃ in 50 mbar wet and dry nitrogen, respectively. They both increased with an increase in the fluence of silicon implantation from 4 x 10~(14) cm~(-2) to 4 x 10~(15) cm~(-2). Furthermore, the mechanism in the films after RTA at 1050℃ in 50 mbar wet nitrogen tended to disappear when 50nm of the top layer was etched from the as-implanted 4 x 10~(15) cm~(-2) 100-nm-thick SiO_2 film before RTA. However, the other mechanism in the films after isochronal RTA in dry nitrogen increased with decreasing residual film thickness to a value of 50 nm. Lastly, the mechanism in wet-N_2-annealecl as-implanted dry SiO_2 films, increasing with an increase in water flow rate in the RTA process and being not ascribed to an oxygen-deficient structure, was attributed to a hydrogen-related structure because of the presence of Si-O-H structures even after reannealing at 850℃ for < 30 min, which was consistent with the non-bridging oxygen hole centers (NBOHC). The other mechanism in dry-N_2-annealed as-implanted dry SiO_2 films, independent of the nitrogen flow rate, attributed to oxygen-and hydrogen-deficient structures, and disappeared after heating to 600℃, was similar to that of the E′_δ center.