Patent ID: 7241659
Filing Date: 2007-07-10
Classification: H01L

Abstract:
1. A method for forming a volatile memory device, comprising: providing a substrate comprising a pair of neighboring trenches, each comprising a capacitor; and forming a collar insulating layer on an upper sidewall of each trench, wherein the collar insulating layer comprises a low level portion and a high level portion wherein the high level portion is adjacent to a predetermined active area of the volatile memory device, wherein the step of forming the collar insulating layer comprises: forming an insulating layer on the sidewall of the trench overlying the capacitor; forming a first conductive layer overlying the capacitor, wherein the first conductive layer is surrounded by the insulating layer; using a mask layer to cover a portion of the insulating layer adjacent to the predetermined active area; etching the uncovered insulating layer; and removing the mask layer.