Patent ID: 8143124
Filing Date: 2012-03-27
Classification: H01L,H02M,Y02B

Abstract:
1. A method of of manufacturing a semiconductor device having a charge control trench and an active control trench with a thick oxide bottom comprising: forming a drift region of a first conductivity type; forming a well region extending above the drift region and having a second conductivity type opposite the first conductivity type; forming an active trench extending through the well region and into the drift region; forming a charge control trench extending deeper into the drift region than the active trench; forming an oxide film that fills the active trench, the charge control trench and covers a top surface of the substrate; etching the oxide film off the top surface of the substrate and inside the active trench to leave a substantially flat layer of thick oxide having a target thickness at the bottom of the active trench; forming an electrode in the active trench; and forming source regions having the first conductivity type in the well region adjacent the active trench.