United States Patent 4,213,806
July 22, 1980

Forming An IC Chip With Buried Zener Diode
Wei K. Tsang

Filed October 5, 1978
Image of US PATENT 4,213,806

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 buried n+ layer; next, a shallow p+ diffusion 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 an IC diode fabricated in accordance with this invention.

 Citations [54]:
3,378,915 04/1968 Zenner 3,765,961 10/1973 Mar 3,881,179 04/1975 Howard 3,886,001 05/1975 Dobkin 4,099,998 07/1978 Ferro et al 4,136,349 01/1979 Tsang
National Museum of American History
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