Subsurface zener diode and method of making

Details Subsurface zener diode and method of making Subsurface zener diode and method of making

1986-05-05

1987-07-28

James, Andrew J.

357 88, 357 90, 357 52, H01L 2990

Patent

active

046834834

ABSTRACT:
A subsurface zener diode is formed in an N.sup.- epitaxial region formed on a P type substrate. The N.sup.- epitaxial region is isolated by a P.sup.+ isolation region. An N.sup.+ buried layer region is disposed between a portion of the N.sup.- epitaxial region and the P type substrate. A first P.sup.+ region is formed in the middle of the N.sup.- epitaxial region at the same time as the P.sup.+ isolation regions. Second and third adjacent P.sup.+ regions also are formed in the N.sup.- epitaxial region adjacent to and slightly overlapping the first P.sup.+ region, all three P.sup.+ regions terminating at the N.sup.+ buried layer. An N.sup.+ region, formed during an emitter diffusion operation, has first and second opposed edges centered within the overlapping portions of the first, second, and third P.sup.+ regions. Two other opposed edges of the N.sup.+ region extend beyond the other edges of the first P.sup.+ region, forming N.sup.+N.sup.- contacts to the N.sup.- epitaxial region, enabling it to be reverse biased without an additional N.sup.+ contact region and a corresponding metal conductor. Masking alignment tolerances in the direction of the N.sup.+ N.sup.- overlap are eased, increasing overall processing yields.

REFERENCES:
patent: 3881179 (1975-04-01), Howard, Jr.
patent: 4127859 (1978-11-01), Nelson
patent: 4136349 (1979-01-01), Tsang
patent: 4213806 (1980-07-01), Tsang
"The Theory and Practice of Microelectronics", Ghandhi, 1968, p. 390, Wiley & Sons, N.Y.
"On-Chip Heater Helps to Stabilize Monolithic Reference Zener", Dobkin, Electronics, 9/16/76, pp. 106-112.

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