Patent ID: 8822330

Claim:
A method of providing an oxide layer on a semiconductor substrate, the method comprising: providing a semiconductor substrate, wherein the semiconductor substrate comprises: a device substrate formed of a doped semiconductor material and comprising isolation zones formed therein, the isolation zones comprising an isolation dielectric material, a multilayer interconnect structure formed over the device substrate, and an insulating layer interposed between the device substrate and the multilayer interconnect structure, wherein the insulating layer at least partially overlaps the isolation zones when viewed in a direction perpendicular to a major surface of the device substrate, and wherein the insulating layer contacts the isolation zones in an overlapping area; providing at least one hole at a backside of the device substrate to the insulating layer through one of the isolation zones; and after providing the semiconductor substrate and the at least one hole, anodizing the semiconductor substrate in an acidic electrolyte solution, wherein the anodizing process forms an oxide layer on the semiconductor substrate, wherein the anodizing process comprises: immersing the semiconductor substrate in the electrolyte solution; and applying a potential between a cathode located in the electrolyte solution and the device substrate being used as an anode, thereby forming the oxide layer on those locations where the semiconductor substrate has the anode exposed to the electrolyte solution; and wherein anodization is performed by a two-step process, wherein applying a potential is performed such that first a fixed current density is obtained through the semiconductor substrate for a predetermined time period; and after the predetermined time period, a fixed potential is applied.