Mech1anism and Control Technology of Trench Corner Rounding by Hydrogen Annealing for Highly Reliable Trench MOSFET

The shape transformation mechanism of micron-size silicon trenches during high-temperature annealing (≥°) in hydrogen ambient was studied, focusing on the effect of hydrogen pressure on the trench corner curvature. Results demonstrated the effectiveness of this hydrogen annealing process on the reliability of gate SiO
2
films; after hydrogen annealing at 1030°C for 1 min, the leakage current through trench gate SiO
2
as a function of applied voltage to the poly-Si gate was suppressed by over 2 orders of magnitude. The time-dependent dielectric breakdown (TDDB) characteristics of the trench gate SiO
2
under a constant applied stress current of 50mA/cm
²
was significantly improved by hydrogen annealing in the initial stage (<100sec) of dielectric breakdown.