Patent ID: 6478978
Filing Date: 2002-11-12
Classification: H01L,Y10S

Abstract:
A method of forming silicon nitride spacers, comprising:forming a transistor gate assembly over a semiconductive substrate, the semiconductive substrate comprising a surface having a center and an edge; forming a silicon dioxide layer proximate the transistor gate assembly; forming a silicon nitride layer over the transistor gate assembly and over the silicon dioxide layer; first etching the silicon nitride in a reaction chamber, the first etching comprising a first center-to-edge uniformity across the surface of the wafer and comprising a first selectivity for the silicon nitride relative to the silicon oxide; second etching the silicon nitride in the reaction chamber, the second etching comprising a second center-to-edge uniformity across the surface of the wafer and comprising a second selectivity for the silicon nitride relative to the silicon oxide, the second center-to-edge uniformity being less than the first center-to-edge uniformity, the second selectivity being greater than the first selectivity, the first and second etchings patterning the silicon nitride into spacers proximate the transistor gate; and cleaning a component of the silicon nitride from at least one sidewall of the reaction chamber between the first etching and the second etching.