Methods for forming bipolar transistors

摘要

Methods are provided for forming a device that includes merged vertical and lateral transistors with collector regions of a first conductivity type between upper and lower base regions of opposite conductivity type that are Ohmically coupled via intermediate regions of the same conductivity type and to the base contact. The emitter is provided in the upper base region and the collector contact is provided in outlying sinker regions extending to the thin collector regions and an underlying buried layer. As the collector voltage increases part of the thin collector regions become depleted of carriers from the top by the upper and from the bottom by the lower base regions. This clamps the collector regions' voltage well below the breakdown voltage of the PN junction formed between the buried layer and the lower base region. The gain and Early Voltage are increased and decoupled and a higher breakdown voltage is obtained.

主权项

1. A method for forming a bipolar transistor, comprising:
forming an emitter region at a surface of the bipolar transistor; forming a base region comprising upper portions surrounding the emitter region, lower portions, and intermediate portions Ohmically coupling the upper and lower portions, wherein the upper portions, the lower portions, and the intermediate portions form a continuous region of a first conductivity type; forming a base contact of the first conductivity type at the surface of the bipolar transistor and positioned within the base region above the intermediate portions; and forming a collector region of a second, opposite, conductivity type comprising finger regions laterally extending into part of the base region so that the upper portions of the base region lie above the finger regions and the lower portions of base region lie below the finger regions, wherein the finger regions underlie an entirety of the emitter region.