Comparative study of annealing and oxidation effects in a-SiC:H and a-SiC thin films deposited by radio-frequency magnetron sputtering

摘要

Thermal annealing and oxidation effects in hydrogenated (a-SiC:H) and nonhydrogenated (a-SiC) amorphous silicon-carbon alloy films deposited by radio-frequency magnetron sputtering have been studied. The a-SiC:H and a-SiC films were thermally treated in dry Ar, wet Ar, and dry O_2 atmospheres at temperatures up to 1150 ℃. The principal effects of thermal annealing in an inert atmosphere on a-SiC:H films were found to be redistribution of hydrogen bonds and formation of amorphous graphitic carbon clusters. Strong oxidation of a-SiC:H was observed after thermal treatment in oxygen at 700 ℃ while annealing in wet argon caused partial oxidation. Oxidation of the carbon clusters in porous a-SiC:H structures is suggested to be responsible for the higher oxidation efficiency of a-SiC:H in oxygen. In contrast, the structure of a-SiC films remained almost unchanged after annealing in dry argon up to 1000 ℃. No oxidation of a-SiC was detected until 1000 ℃. Water vapor was found to be more effective at oxidizing a-SiC at 1000 ℃ than dry oxygen, which is similar to the oxidation behavior of crystalline SiC. The high thermal and oxidation stabilities of a-SiC layers were attributed to the dense and nanovoid-free amorphous SiC network.