United States Patent 4,136,349
January 23, 1979

IC Chip With Buried Zener Diode
Wei K. Tsang

Filed May 27, 1977
Image of US PATENT 4,136,349

Abstract of the Disclosure

An IC chip having a Zener diode with a subsurface breakdown junction to assure stable operation. The diode is formed by a triple diffusion process compatible with conventional bipolar processing. A deep p++ diffusion first is applied, reaching through the epitaxial region to the buried n+ layer; next, a shallow p+ diffussion is formed over the deep p++ diffusion and extending laterally beyond that diffusion; finally, a shallow n+ diffusion is applied over the p diffusions, to form a subsurface breakdown junction therewith . The topology of the mask windows is selected to provide concentration profiles which insure that the breakdown occurs at the subsurface junction, and that other desirable diode characteristics are achieved
Figure descriptions: cover graphic

  • a cross-section view of a configuration of the three mask windows used to control the diffusion pattern for a diode in accordance with this invention.

 Citations [54]:
3,378,915 04/1968 Zenner 3,881,179 04/1975 Howard
National Museum of American History
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