Method of manufacturing heterojunction transistors with self-aligned metal contacts
A method of manufacturing heterojunction transistors having
self-aligned contacts. In manufacturing a heterojunction bipolar
transistor, a collector and a base layer are deposited on a
substrate. A masking layer is deposited on the base layer and
selectively etched to form an aperture therein, exposing the base
layer. An emitter having a mesa structure is grown epitaxially on
the exposed base layer to produce lateral overhang portions. The
overhang portions may be formed by continuing the epitaxial growth
to form lateral overgrowth portions overlapping the masking
material. The masking layer is removed and self-aligned contacts
are formed to the base and emitter regions using the lateral
overhang portions which provide separation between the emitter
structure and the contacts to the base layer.
Enquist, P., & Slater, DB. (1993). IPC No. U.S. Method of manufacturing heterojunction transistors with self-aligned metal contacts. (Patent No. 5272095).