United States Patent 3,490,962
January 20, 1970

Diffusion Process
Micahel C. Duffy
David P. Kennedy
Philip C. Murley
William J. Armstrong
Jack J. Seabolt

Filed April 25, 1966
Image of US PATENT 3,490,962

Abstract of the Disclosure

A method of forming a high speed transistor by providing a mask on the surface of a semiconductor, the mask having an opening width of less than 4.45 multiples of an atom diffusion length of a given impurity of one conductivity type, exposing the surface through the opening to an atmosphere containing the given impurity to form a highly doped surface region, heating the substrate in an atmosphere having a lesser concentration of the given impurity to form a collector-base junction and forming by diffusion through the same opening an emitter-base junction.
Figure descriptions: cover graphic

  • Figure 1 is a flow diagram illustrating a preferred process of the present invention.
  • Figure 6 shows the temperature coefficient of resistance as a function of surface concentration for boron diffused resistors.
  • Figure 7 is a series of curves showing junction depth as a function of mask opening width.

 Citations [54]:
2,873,222 02/1959 Derick 3,165,430 01/1965 Hugle 2,981,645 04/1961 Tucker 3,246,214 04/1966 Hugle 2,981,877 04/1961 Noyce 2,802,760 08/1957 Derick 3,006,789 10/1961 Nijland 3,025,589 03/1962 Hoerni
National Museum of American History
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