Patent ID: 11876123
Assignee: GLOBALFOUNDRIES U.S. INC.
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 15:
16. A method of forming a heterojunction bipolar transistor (HBT) structure, comprising:
providing a substrate
forming a collector in the substrate;
forming a base on the collector, the base comprising an extrinsic base and an intrinsic base;
forming an emitter on the base, wherein the emitter, the base, and the collector comprise an active device;
forming a shallow trench isolation (STI) structure around the active device;
forming a dielectric layer on the base positioned laterally adjacent to the emitter;
forming a trench extending through the dielectric layer and the base and at least partially into the collector so that the collector is immediately adjacent to the trench, so that the base is immediately adjacent to the trench, and so that the emitter is separated from the trench, wherein either the trench is positioned between the STI structure and the active device or the STI structure is positioned between the trench and the active device, and wherein the trench undercuts at least a portion of the intrinsic base; and
forming a core in the trench in contact with the collector and the base and separated from the emitter by at least a portion of the dielectric layer, wherein the core comprises a compressive material.