News Column

Patent Issued for Bipolar Transistor in bipolar-CMOS Technology

July 1, 2014

By a News Reporter-Staff News Editor at Journal of Technology -- A patent by the inventors Yasuda, Hiroshi (Plano, TX); Staufer, Berthold (Moosburg, DE), filed on August 15, 2013, was published online on June 17, 2014, according to news reporting originating from Alexandria, Virginia, by VerticalNews correspondents.

Patent number 8754484 is assigned to Texas Instruments Incorporated (Dallas, TX).

The following quote was obtained by the news editors from the background information supplied by the inventors: "An integrated circuit may include bipolar transistors and metal oxide semiconductor (MOS) transistors. Regarding the bipolar transistors, it may be desirable to simultaneously attain desired levels of transfer frequency, collector-base breakdown voltage and base resistance. Regarding integration of the bipolar transistors and MOS transistors into the integrated circuit, it may be desirable to reduce fabrication cost and complexity of the integrated circuit."

In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventors' summary information for this patent: "The following presents a simplified summary in order to provide a basic understanding of one or more aspects of the invention. This summary is not an extensive overview of the invention, and is neither intended to identify key or critical elements of the invention, nor to delineate the scope thereof. Rather, the primary purpose of the summary is to present some concepts of the invention in a simplified form as a prelude to a more detailed description that is presented later.

"An integrated circuit may be formed so as to include a bipolar transistor and an MOS transistor. The bipolar transistor may have a collector disposed in a substrate of the integrated circuit, abutted by field oxide. The bipolar transistor may further have a base on the collector and overlapping the adjacent field oxide, formed by a non-selective epitaxial process, so that a portion of the base on the collector is crystalline and a portion of the base on the field oxide is polycrystalline. The bipolar transistor may also have an emitter on the base. The MOS transistor may have a gate with an average doping density between 80 percent and 125 percent of an average dopant density in the polycrystalline region of the base over the field oxide.

"The integrated circuit may be formed by forming field oxide at the top surface of the substrate so as to provide the collector between two adjacent field oxide regions. A base layer is then formed on the collector, overlapping the adjacent field oxide, using a non-selective epitaxial process, so that a portion of the base layer on the collector is crystalline and a portion of the base layer on the field oxide adjacent to the collector is polycrystalline. An ion implant operation is performed which provides dopants to the base by ion implanting dopants into the base layer in an area laterally separated from the collector while blocking the dopants from the base layer over the collector, and concurrently ion implanting dopants into a gate layer over an area for the MOS transistor. The gate layer is subsequently patterned to form a gate of the MOS transistor. An emitter layer is formed on the base and patterned to form an emitter of the bipolar transistor. After a subsequent anneal operation, the dopant density in the base layer and in the MOS gate are as described above."

URL and more information on this patent, see: Yasuda, Hiroshi; Staufer, Berthold. Bipolar Transistor in bipolar-CMOS Technology. U.S. Patent Number 8754484, filed August 15, 2013, and published online on June 17, 2014. Patent URL:

Keywords for this news article include: Technology, Texas Instruments Incorporated.

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Source: Journal of Technology

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