The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 31, 1998
Filed:
Aug. 30, 1995
Burhan Bayraktaroglu, Huber Heights, OH (US);
Lee L Liou, Dayton, OH (US);
Chern I Huang, Beavercreek, OH (US);
Abstract
Structure and fabrication details are disclosed for AlGaAs/GaAs microwave HBTs having improved thermal stability during high power operation. The use of a thermal shunt joining emitter contacts of a multi-emitter HBT is shown to improve this thermal stability and eliminate 'current-crush' effects. A significant reduction in thermal resistance of the disclosed devices is also achieved by spreading the generated heat over a large substrate area using thermal lens techniques in the thermal shunt. These improvements achieve thermally stable operation of AlGaAs/GaAs HBTs up to their electronic limitations. A power density of 10 mW/.mu.m2 of emitter area is achieved with 0.6 W CW output power and 60% power-added efficiency at 10 GHz. The thermal stabilization technique is applicable to other bipolar transistors including silicon, germanium, and indium phosphide devices. The disclosed fabrication sequence employs an improved two-step polyimide electrical isolation planarization sequence in preparation for fabrication of the thermal shunting element.