Formation of sidewall oxide layers by reactive oxygen ion etching to define submicron features

A method for forming a submicron feature by forming a sidewall oxide layer on a vertical sidewall of a first layer of first material located on a limited portion of a second layer of second material, different from the first, said second layer located over a horizontal major surface of a semiconductor body, comprising a first step of reactive ion etching said second layer to form by back-sputtering of said second material a sidewall oxide layer on the vertical sidewall of the first layer whereby the thickness of the second layer is reduced by said reactive ion etching, and a second step of using said sidewall oxide layer as a protective mask for defining said feature.

A method for fabricating an insulated gate field effect transistor in which a gate oxide layer is grown on a major horizontal surface of a silicon body and a polycrystalline silicon gate electrode having a vertical sidewall is formed on a limited portion of the surface of the gate oxide layer comprising the step of forming an insulating layer of predetermined thickness on said sidewall by subjecting an exposed portion of the gate oxide layer, complementary to said limited portion, to reactive ion etching with oxygen to expose the major surface of the body underlying said complementary portion, and whereby the thickness of the exposed portion of the gate oxide layer is reduced.