International Business Machines Corporation

Globalfoundries Inc.

Globalfoundries U.S. Inc.

Paula Fisher

Qizhi Liu

Glenn C MacDougall

Joseph P Hasselbach

Margaret A Faucher

Thomas H Gabert

Vibhor Jain

Mark Levy

James Randall Elliott

Sarah A McTaggart

Device structures and fabrication methods for heterojunction bipolar transistors. Trench isolation regions are positioned in a semiconductor substrate to define active regions. A base layer includes first sections that are respectively positioned over the active regions and second sections that are respectively positioned over the trench isolation regions. Emitter fingers are respectively positioned on the first sections of the base layer. The first sections of the base layer include single-crystal semiconductor material, and the second sections of the base layer include polycrystalline semiconductor material. The second sections of the base layer are spaced in a vertical direction from the trench isolation regions to define a first cavity that extends about a perimeter of the base layer and second cavities that are connected to the first cavity.

Heterojunction bipolar transistors with undercut extrinsic base regions

Aspects of the invention provide a method of forming a bipolar junction transistor. The method includes: providing a semiconductor substrate including a uniform silicon nitride layer over an emitter pedestal, and a base layer below the emitter pedestal; applying a photomask at a first end and a second end of a base region; and performing a silicon nitride etch with the photomask to simultaneously form silicon nitride spacers adjacent to the emitter pedestal and exposing the base region of the bipolar junction transistor. The silicon nitride etch may be an end-pointed etch.

Self-aligned emitter-base region

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Milton, VT, United States of America

Paula Fisher