Method for forming aluminum oxide dielectric isolation in integrated circuits

Claim 1

In the fabrication of integrated circuits, a method for forming dielectrically isolated regions in a semiconductor substrate comprising the steps of: forming over said semiconductor substrate surface, an electrically insulating layer of dielectric material having a plurality of openings therethrough, etching to form recesses in the semiconductor substrate exposed in said openings, forming a thin layer of silicon dioxide in said recesses, said thin layer of silicon dioxide having a maximum thickness of 200 Å, depositing aluminum on said layer of dielectric material and depositing aluminum spaced therefrom in said recesses, fully anodizing the aluminum in said recesses in an aqueous electrolytic solution, by applying a positive bias voltage to said semiconductor substrate to thereby subject the aluminum in said recesses to said bias voltage and anodize the aluminum in said recesses to aluminum oxide, the thickness of said thin layer of silicon dioxide being insufficient to insulate the aluminum in said recesses from said positive bias voltage, the thickness of said electrically insulating layer of dielectric material being sufficient to electrically insulate the aluminum thereon from said positive bias voltage so that it remains substantially unanodized, and removing the aluminum deposited on said layer of dielectric material.