Appeal No. 1996-4082
Application 08/179,238
2 3
18 to 32. Claims 13 to 15 have been canceled. Claims 16 and 17 stand withdrawn.
BACKGROUND
The subject matter on appeal is directed to the field of semiconductor electronic integrated
circuits, and particularly to a heterojunction bipolar transistor (see appellant’s specification, page 1).
As indicated in the specification (page 2), the prior art recognized a need for heterojunction bipolar
transistors having the characteristic properties of both a thin base layer and a low base resistance.
Appellant recognized that prior art heterojunction bipolar transistors suffered from difficulties in
fabrication during etching such as difficulty in stopping etching at the base without penetrating it when
selectively removing the emitter from the base, and difficulty in precisely controlling device parameters
such as threshold voltage (specification, pages 1 to 3). To overcome this problem, appellant provides a
heterojunction bipolar transistor with a collector region under an etch stop layer, thereby overcoming
the problem in the prior art of selectively removing the emitter from the base during etching, lowering
the surface potential, solving the threshold problem, and improving ohmic contact properties
(specification, page 4).
As further discussed, infra, we find that the applied references to Lunardi and Adlerstein,
whether taken singly or in any combination thereof, fail to teach or suggest at least the feature of a
2Claims 13 to 15 were canceled as per appellant’s amendment dated January 10, 1994.
3Claims 16 and 17 were withdrawn from consideration by the examiner as per page 2 of the the office action
dated July 12, 1994.
2
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