Appeal No. 1999-2838
Application No. 08/812,848
plurality of very lightly doped spaced concentric P type
diffusion rings in the N epitaxial layer of the device
surrounding the outer periphery of the device active area. The
low dose P type diffusion rings have a concentration produced by
an implant dose of from about 2E12 to 2E13 atoms/cm which,2
according to Appellant (specification, page 3), serves to lower
the electric field at the surface of the epitaxial layer.
Claim 1 is illustrative of the invention and reads as
follows:1
1. A termination structure for a semiconductor die; said
semiconductor die having a body of silicon of one of the
conductivity types and an upper N epitaxial layer for receiving
diffusions therein; said N epitaxial layer having an active area
diffused therein; a first electrode means connected to said
active area; said active area having an outer periphery; said N
epitaxial area and said die having an outer peripheral street;
said first electrode and said street being connectable to
potential differences in excess of about 600 volts; said
termination structure comprising a plurality of spaced
concentric P type diffusion rings in said N epitaxial layer
surrounding said outer periphery of said active area to
distribute the electric field between said first electrode and
said street; said P type diffusion rings having a concentration
produced by an implant does [sic, dose] of from about 2E12 to
2E13 atoms/cm to reduce the electric field at the surface of2
said N epitaxial layer and to prevent their complete depletion
at full reverse voltage.
The Examiner relies on the following prior art:
1 The word “dose” is misspelled at line 15 of claim 1.
2
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