United States Patent 3,488,235
January 6, 1970

Triple-Epitaxial Layer High Power, High Speed Transistor
Donald A. Walczak
Peter J. Kannam

Filed April 25, 1967
Image of US PATENT 3,488,235

Abstract of the Disclosure

This invention provides a high power, high speed transistor comprising three epitaxial layers of semiconductor material grown on a substrate surface at least 1 inch in diameter. The chemical etching of the large area of the substrate upon which the epitaxial layers are grown and the growth of each of the three epitaxial layers is accomplished in one continuous process. Each epitaxial layer is grown to a desired thickness and has a specific type of semiconductivity as well as a preferred level of impurity concentration.
Figure descriptions: cover graphic

  • Figures 1 through 4 are views in cross-section of a body of a semiconductor material being processed in accordance with the teachings of this invention.
  • Figure 5 is a top view of a semiconductor device showing a preferred emitter edge design.
  • Figures 6 through 8 are cross-sectional views of the body of semiconductor material being processed further in accordance with the teachings of this invention.

 Citations [54]:
3,192,083 06/1965 Sirtl 3,260,624 07/1966 Wiesner
National Museum of American History
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