With Emitter Region Having Specified Doping Concentration Profile (e.g., High-low Concentration Step) Patents (Class 257/591)
  • Semiconductor device including bipolar transistor with step impurity profile having low and high concentration emitter regions
    Patent number: 5198692
    Abstract: In a semiconductor device including a bipolar transistor having a base region formed in a collector region, and an emitter region formed in the base region, the emitter region comprises a high concentration region in contact with the base region, and a low concentration region provided between the base region and the high concentration region. The low concentration region is formed by introducing an impurity with a mask including a large opening. In addition, the high concentration region is formed by introducing an impurity with a mask including a small opening.
    Type: Grant
    Filed: June 14, 1991
    Date of Patent: March 30, 1993
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Hisayo Momose