Patent ID: 6699775
Filing Date: 2004-03-02
Classification: H01L

Abstract:
The method of forming a high voltage termination for a semiconductor device with a reduced number of mask steps; said method comprising:(a) forming a relatively thick insulation oxide layer atop the surface of a monocrystalline N type silicon wafer; (b) forming a relatively thin insulation nitride layer atop the surface of said oxide layer; (c) forming a photoresist layer atop said insulation nitride layer; (d) applying a photolithographic mask to said photoresist layer and forming a plurality of spaced windows in said photoresist layer; at least three of said windows being concentric windows which enclose an active region of a die within said wafer which is to be terminated; (e) sequentially opening windows in said nitride layer and said oxide layer by etching through said windows in said photolithographic mask; (f) implanting a P type impurity through said windows in said nitride layer and into the silicon surface portions underlying said windows; (g) heating said wafer to diffuse said implanted P type impurities into said silicon to define at least first and second spaced, concentric guard ring diffusions; (h) depositing a second layer of insulation nitride of the surface of said wafer, with said nitride contacting the surface of silicon exposed by said windows; (i) laterally etching away all oxide regions in the active area of said device; (j) etching all insulation nitride from said surface; (k) depositing a top metal contact layer over the full upper surface of said wafer; (l) forming a contact mask over said full upper surface to define (a) a first contact over the outermost guard ring diffusions (b) a separate first conductive field plate section in contact with said second guard ring diffusion and overlying a portion of said oxide layer disposed between said first and (c) second guard ring diffusions; and a second field plate isolated from said first field plate and overlapping a second portion of said oxide layer which is adjacent said second guard ring diffusion.