Method of making direct metal contact to buried layer

Details Method of making direct metal contact to buried layer Method of making direct metal contact to buried layer

1976-12-17

1978-05-02

Tupman, W.

Metal working

Method of mechanical manufacture

Assembling or joining

29580, 29589, 96 362, B01J 1700

Patent

active

040866947

ABSTRACT:
An integrated circuit having a direct metal contact to a buried layer is fabricated by first diffusing said buried layer into a substrate and growing thereon an epitaxial layer. After emitter diffusion into the epitaxial layer and emitter oxidation, a sink hole is etched through the oxide mask, the epitaxial layer, and into the buried layer. An oxide layer is then grown over the surface of the sink hole; which oxide layer is then coated with a negative photoresist. The negative photoresist is exposed to collimated light at an incident angle which results in an unexposed area of photoresist at the bottom of the sink hole. The unexposed area is washed off during developing and the exposed oxide etched away, thereby exposing the buried layer. A metal may be deposited, for example, by evaporation, thus creating a direct metal contact to the buried layer. Also, similar techniques with appropriate variations can be used for direct metal contact to the substrate from the top of the wafer, especially significant whenever insulator isolation processes are employed.

REFERENCES:
patent: 3457631 (1969-07-01), Hall
patent: 3518509 (1970-06-01), Cullis
patent: 3760239 (1973-09-01), Fletcher
patent: 3768150 (1973-10-01), Sloan
patent: 3908262 (1975-09-01), Stein
patent: 3913124 (1975-10-01), Roberson
patent: 4005452 (1977-01-01), Cook

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