The effects of hydrogen annealing on gate oxide integrity of U-shaped trench MOSFET with 400 A gate oxide

The effects of hydrogen (H-2) annealing on the thick gate oxide integrity of the U-shaped trench metal-oxide- semiconductor-field effect transistor (UMOSFET) were investigated. H-2 annealing was performed after trench etch and before gate oxidation. It was observed that the gate oxide integrity (GOI) of the 400 gate oxide grown after H-2 annealing can be comparable to the standard approach (soft etch and sacrificial oxidation) when the trench width is kept at 0.65 mu m. When the trench width was reduced to 0.45 mu m the GOI of H-2 annealing samples was degraded slightly due to faceting at the transition region between trench sidewall and bottom. It was proven that using high-temperature gate oxidation, the UMOSFET with 0.45 mu m trench width and H-2 annealing has very high-quality gate oxide. The reduction of process steps and time and the potential for narrower trench make H-2 annealing an attractive process in trench MOSFET processing. (c) 2006 The Electrochemical Society.