Appeal No. 2006-1797
Application No. 09/866,319
Invention
Appellants’ invention relates generally to a high voltage
silicon germanium (SiGe) heterojunction bipolar transistor having
improved AC performance. The SiGe bipolar transistor includes an
emitter (28), a base (22), a collector (14), isolation regions
(20) and a base collector junction. The collector includes a
subcollector region (12) a deep collector region (16) and an n-
type dopant region (18) between the subcollector (12) and the
base collector junction. The n-type dopant region (18) is
located atop and in contact with the deep collector (16).
Further, the n-type dopant region has a vertical width
sufficiently narrow to avoid lowering the collector-base
breakdown voltage and a dopant concentration sufficiently high to
restrict the base widening when the base-emitter junction is
forward biased.
Claim 45 is representative of the claimed invention and is
reproduced as follows:
45. A method of fabricating a bipolar device comprising the
steps of:
(a) providing a structure comprising at least a sub-
collector region, a collector region and isolation
regions, said collector region including a deep
collector region located therein;
(b) forming a n-type dopant region within said collector
region so as to be in contact with said deep collector,
said n-type dopant region having a vertical width
2
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