Patent ID: 8722549

Claim:
A method of fabricating a semiconductor device on a p-type semiconductor substrate, wherein said p-type semiconductor substrate has a front surface and a back surface, said semiconductor device is formed on the front surface of said p-type semiconductor substrate, said method comprising: before forming metal interconnections on the front surface of said p-type semiconductor substrate, doping the back surface of said p-type semiconductor substrate with an n-type dopant to form an n-type semiconductor region on the back surface of said p-type semiconductor substrate, wherein said n-type semiconductor region and said p-type semiconductor substrate together form a pn junction, and after the formation of the n-type semiconductor region and before forming metal interconnections, forming an insulation layer on an exposed surface of said n-type semiconductor region, wherein forming the insulating layer comprises implanting nitrogen ions to the exposed surface of the n-type semiconductor region to form a silicon nitride film.