Appeal No. 1998-2924
Application NO. 08/276,290
(a) forming, in respective first and second spaced-apart
portions of a semiconductor substrate of a first conductivity
type, first and second well regions of a second conductivity
to a first depth from a first surface of said substrate;
(b) forming a first channel conductivity type MOS
structure formed in said first well region by introducing
first source and drain regions of said first conductivity type
in spaced apart surface portions of said first well region,
such that said first source and drain regions have a first
doping and a second depth from said first surface, less than
said first depth;
(c) forming, in said second spaced-apart portion of said
substrate including said second well region, a bipolar
transistor structure having an emitter region of said first
conductivity type, a base region of said second conductivity
type and a collector region of said first conductivity type,
such that said second well region forms said base region and
said substrate forms said collector region;
(d) forming a second channel conductivity type MOS
structure formed in said substrate by introducing second
source and drain regions of said second type in spaced apart
surface portions of said substrate adjacent to said first well
region containing said first channel conductivity type MOS
structure; and
(e) performing local oxidation of on the surface of said
substrate to form a field oxide having an aperture
therethrough overlying said second well region, such that a
first 'bird's peak' edge of said aperture through said field
oxide is spaced apart from said emitter region by a distance
sufficient to prevent radiation incident upon said field oxide
from initiating parasitic channel turn-on in surface portion
of said second well region between said emitter region and
said substrate.
18
Page: Previous 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 Next
Last modified: November 3, 2007