Patent ID: 8378457
Filing Date: 2013-02-19
Classification: H01L

Abstract:
1. A silicon-germanium heterojunction bipolar transistor, formed on a P-type silicon substrate, wherein, an active area is isolated by field oxide regions, and the silicon-germanium heterojunction bipolar transistor comprises: a collector region, composed of an N-type ion implantation region formed in the active area, wherein, the collector region has a depth larger than that of the bottom of the field oxide regions and the collector region laterally extends into the bottom of the field oxide regions on both sides of the active area; pseudo buried layers, composed of N-type ion implantation regions formed at the bottom of the field oxide regions on both sides of the active area; each pseudo buried layer is separated by a lateral distance from the active area in a lateral direction, and is in contact with a lateral extension part of the collector region which laterally extends into the bottom of the field oxide regions; a breakdown voltage of the silicon-germanium heterojunction bipolar transistor is adjustable by adjusting the lateral distances between the pseudo buried layers and the active area; first deep hole contacts, respectively formed on top of a pseudo buried layer through the respective field oxide region and connected to the pseudo buried layer; each first deep hole contact picks up a collector electrode by connecting to an upper metal layer; a plurality of second deep hole contacts formed in the field oxide region on top of a lateral extension part of the collector region and connected to the lateral extension part, wherein, an N-type implantation region is formed at a contact area between each second deep hole contact and the lateral extension part of the collector region; the doping concentration of the N-type implantation regions satisfies the condition to form an ohmic contact between the N-type implantation region and a metal of the respective second deep hole contact; top parts of the second deep hole contacts are not connected to the upper metal layer so as to form floating structures; a base region, composed of a P-type silicon-germanium epitaxial layer formed on the silicon substrate; the base region comprises an intrinsic base region which is formed on top of the active area and forms a contact with the collector region, and an extrinsic base region which is formed on top of the field oxide regions for forming a base electrode; an emitter region, composed of an N-type polysilicon formed on top of the intrinsic base region and forming a contact with the intrinsic base region.