Patent ID: 6399410
Filing Date: 2002-06-04
Classification: B81B,B81C,G01P

Abstract:
A method for anodizing a silicon substrate comprising:providing a p-type single crystal silicon substrate; forming an n-type silicon embedded layer made of n-type silicon on a predetermined area of a first surface of the p-type single crystal silicon layer, wherein an opening for permitting a current to flow is formed in the center of the n-type silicon embedded layer; forming an n-type silicon layer on the first surface of the p-type single crystal silicon substrate and on the n-type silicon embedded layer; forming a silicon diffusion layer containing a high-concentration p-type impurity on a predetermined area of the n-type silicon layer, wherein the silicon diffusion layer contacts the n-type silicon embedded layer in the vicinity of the interface between the p-type single crystal silicon substrate and the n-type silicon embedded layer, and wherein a gap is defined between the first surface of the p-type silicon substrate and the silicon diffusion layer; forming an electrode layer on a second surface, which is on the opposite side of the p-type silicon substrate from the first surface; connecting the anode of a DC power source to the electrode layer and connecting the cathode to a counter electrode, which is opposed to the p-type silicon substrate; and concentrating a current flow to an area corresponding to the opening of the n-type silicon layer in a direction from the second surface of the p-type single crystal silicon substrate toward the first surface, and advancing porosity formation in the area from the first surface toward the second surface.