US 5,397,720 A · Method of making MOS transistor having improved oxynitride dielectric

Abstract

High quality ultrathin gate oxides having nitrogen atoms therein with a profile having a peak at the silicon oxide-silicon interface are formed by oxidizing a surface of a monocrystalline silicon body in an atmosphere of nitrous oxide (N.sub.2 O) at a temperature above 900.degree. C. preferably in the range of 900.degree.-1100.degree. C., and then heating the silicon body and oxidized surface in an atmosphere of anhydrous ammonia to introduce additional nitrogen atoms into the oxide and increase resistance to boron penetration without degrading the oxide by charge trapping. The resulting oxynitride has less degradation under channel hot electron stress and approximately one order of magnitude longer lifetime than that of conventional silicon oxide in MIS applications.

Claims18

Dependent claims

A method of fabricating an MIS transistor comprising the steps of

a) providing a monocrystalline silicon substrate having a major surface,
b) cleaning said major surface,
c) placing said body in an atmosphere of nitrous oxide,
d) heating said body and atmosphere at a temperature for the oxidation of said major surface thereby forming a oxynitride layer with nitrogen atoms therein,
e) heating said silicon substrate and oxynitride layer in an atmosphere of anhydrous ammonia to introduce additional nitrogen atoms in said oxynitride layer,
f) annealing said silicon substrate and oxynitride layer in an atmosphere of nitrogen,
g) forming a gate electrode on said oxynitride layer, and
h) forming a source region and a drain region in said silicon body abutting said major surface and aligned with said gate electrode.

5 more elements

Dependencies are inferred from the claim text.

Method of making MOS transistor having improved oxynitride dielectric

Life of this patent

Method of making MOS transistor having improved oxynitride dielectric

Life of this patent

Abstract

Claims18