Patent ID: 8008144
Filing Date: 2011-08-30
Classification: H01L

Abstract:
1. A method of forming a recessed access device, comprising: providing a semiconductor substrate having at least one trench formed therein; forming a gate-oxide layer over a surface of the at least one trench; forming a layer of substantially uniform thickness of a first gate material having a first work function over at least a portion of the gate-oxide layer in a bottom portion of the at least one trench, the first gate material comprising material selected from the group consisting of p-type doped polysilicon, titanium nitride (TiN), tantalum nitride (TaN), tungsten nitride (WN), ruthenium (Ru), molybdenum nitride (MoN), TaN/TiN, WN/TiN, p-type polysilicon/TiN, and combinations thereof; removing at least a portion of the layer of first gate material to expose at least a portion of the gate-oxide layer in the at least one trench; forming a second gate material having a second work function over the first gate material in at least a portion of the at least one trench, wherein the second work function is lower than the first work function; and forming a third gate material over the first gate material and the second gate material, wherein the third gate material contacts the at least a portion of the gate-oxide layer in the at least one trench exposed by removing at least a portion of the layer of first gate material.