Growth and reliability of thick gate oxide in U-trench for power MOSFETs

Growth kinetics and reliability of thick gate oxides grown into 2 /spl mu/m deep trenches is investigated. The oxide thickness nonuniformities are observed at the bottom of the trench. It is postulated that thinning of the oxide at the bottom of the trench is a result of an insufficient supply of oxidizing species which nonuniformities are enhanced by 2D oxidation in the corners. The effect of 2D oxidation is more pronounced in narrow trenches. The reliability of trench oxides was found to be dependent on the oxidation temperature, trench geometry, and substrate's conductivity type. No effect of temperature of oxidation and trench geometry on interface trap density was observed.