Patent ID: 8252647
Filing Date: 2012-08-28
Classification: H01L

Abstract:
1. A method for fabricating a semiconductor device comprising: a) forming a trench in the semiconductor layer; b) forming an oxide-nitride-oxide (ONO) structure on a sidewall and at a bottom of the trench, wherein the ONO structure includes a nitride layer between first and second oxide layers, wherein forming the ONO structure includes forming a first oxide layer on the sidewall and at the bottom of the trench and on top of the semiconductor layer; forming a nitride layer on top of the first oxide layer; and forming a second oxide layer on top of the nitride layer; and c) forming one or more conductive structures in a portion of the trench not occupied by the ONO structure, wherein the one or more conductive structures include a shield gate structure having an insulating material sandwiched between a first conductive structure and a second conductive structure, wherein forming the second oxide layer includes: filling the trench with the second oxide layer; etching back the second oxide layer to leave a portion of the second oxide at the bottom of the trench; forming a spacer layer with the predetermined thickness T