Patent ID: 9111992
Filing Date: 2015-08-18
Classification: H01L

Abstract:
1. A method for fabricating a device comprising: providing a substrate without doped regions which serve as buried doped regions, wherein the substrate comprises a planar top surface; forming a doped epitaxial layer over and contacts the planar top surface of the substrate, wherein the doped epitaxial layer includes first polarity type dopants and a planar top epitaxial surface, the doped epitaxial layer includes a device region which corresponds to a device isolation well for a device in the device region, and a thickness of the doped epitaxial layer defines a depth of the device isolation well; selectively counter-doping a portion of the doped epitaxial layer to form a counter-doped region adjacent to the device region formed by the doped epitaxial layer, wherein the counter doped region extends from the planar top epitaxial surface to at least the planar top surface of the substrate; forming a trench isolation region, the trench isolation region isolates the device region; and forming the device over and contacts the planar top epitaxial surface in the device region.