Patent ID: 6074929
Filing Date: 2000-06-13
Classification: H01L

Abstract:
A method of fabricating electrically isolated active device regions in a silicon substrate, the method comprising:forming a layer of implant impairing material on the silicon substrate;forming a mask on the layer of implant impairing material such that the mask covers at least one surface region strip of implant impairing material that extends continuously around an internal surface region of implant impairing material that is not covered by the mask;using the mask to etch the implant impairing material such that implant impairing material is etched in the internal surface region to expose an underlying substrate surface region and such that the surface region of implant impairing material that extends continuously around the internal surface region is not etched, thereby creating a continuous wall of implant impairing material around the substrate surface region;removing the mask;implanting oxygen ions into the silicon substrate to provide a substantially horizontal layer of oxygen ions having a peak concentration at a predefined depth in the substrate beneath the substrate surface region, the wall of implant impairing material impairing the implant of oxygen ions such that a continuous substantially vertical wall of oxygen ions is formed in the substrate extending around the entire perimeter of the horizontal oxygen ion layer and extending to the surface of the substrate; andheat treating the substrate to cause the oxygen ions in the substrate to react with silicon in the substrate to form silicon oxide in the substrate that defines a silicon oxide island on all sides except the surface of the substrate, thereby forming an electrically isolated active device region.