Pre-metal deposition cleaning for bipolar semiconductors

Details Pre-metal deposition cleaning for bipolar semiconductors Pre-metal deposition cleaning for bipolar semiconductors

1987-01-13

1988-06-21

Beck, Shrive P.

Coating processes

With pretreatment of the base

Etching, swelling, or dissolving out part of the base

427318, 437228, 134 3, 134 41, 156663, B05D 304, B05D 310

Patent

active

047525053

ABSTRACT:
A pre-metal deposition cleaning process for bipolar semiconductors includes a two step boron glass etching procedure: a chemical etchant consisting of DI, H.sub.2 SO.sub.4, HNO.sub.3 and HCl (500:65:325:163) heated to 80 deg. C. followed by a 10:1 (DI:HF) dip. The semiconductor wafer is then annealed in forming gas. Then the boron glass etching procedure is repeated. The initial etch removes any B-Si-O glass present at base contacts. The anneal removes any fluorine clustered under the boron skin, and the final etch removes any retained B-Si-O-F phase from the anneal step. The cleaning procedure produces bipolar semiconductors with low V.sub.be. The procedure can also be used for rework of high V.sub.be wafers without the anneal and the second boron glass etch steps.

REFERENCES:
patent: 3704208 (1972-11-01), Russo
patent: 4222815 (1980-09-01), Krechmery
patent: 4439270 (1984-03-01), Powell

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