Oppenheimer Wolff & Donnelly LLP
Method to prevent the formation of a thinner portion of insulating layer at the junction between the side walls and the bottom insulator
 A method to prevent the formation of a thinner portion of insulating layer, especially a gate oxide layer, at the junction between the side walls and the bottom insulator is disclosed. First, a pad oxide layer is formed on the side walls and the bottom of the trench. Next, a bottom oxide is formed on the lower portion of the trench. Then, the upper portion of the bottom oxide and the exposed pad oxide layer are removed by wet etching to leave a bottom oxide having a concave surface. Next, the conformal gate oxide layer is grown on the exposed side walls of the trench. 
Mosel Vitelic, Inc.
H H H H H H H
H01L H01L H01L H01L H01L H01L H01L
additional inventional inventional inventional inventional inventional additional
Ping-Wei Ming-Kuan Jui-Ping
Lin Kao Li