Heretojunction bipolar transistor.

摘要

An hereto junction bipolar transistor which features a trapezoidal overhang emitter. In addition to the emitter-base junction (12) being the designed area, the overhang (13) permits a vertical impurity introduction operation via ion implantation to convert adjacent regions (14, 15) of the base layer (5) to high conductivity, shown as P+, to a location (16) proximate to but separated by about 0.2 microns from the emitter-base junction (12). Advantages achieved with this trapezoidal overhang emitter are that a sharp ledge (18) is provided by the trapezoidal shape which serves in future lift-off metallization operations to provide a clear separation and that the height of the emitter which is used in subsequent planarization operations is established by the simple and controllable thickness of a layer.