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Electroless Deposition of Copper

IP.com Disclosure Number: IPCOM000089920D
Original Publication Date: 1968-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Hall, DW: AUTHOR [+2]

Abstract

Copper of high purity and conductivity is electrolessly deposited at temperatures up to 90 degrees C from a bath with the following composition: CuCN 10.7 gm/l 0.12M KCN 15.6 gm/l 0.24M NaOH 42.9 gm/l 1.07M (CH(3))(2)NH BH(3) 28.6 gm/l 0.55M.

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Electroless Deposition of Copper

Copper of high purity and conductivity is electrolessly deposited at temperatures up to 90 degrees C from a bath with the following composition: CuCN 10.7 gm/l 0.12M

KCN 15.6 gm/l 0.24M

NaOH 42.9 gm/l 1.07M

(CH(3))(2)NH BH(3) 28.6 gm/l 0.55M.

This solution is prepared just prior to use by mixing 6 volumes of Solution A and 1 volume of Solution B. Solution A Solution B

CuCN 1.25 gm/l (CH(3))(2)NH BH(3) 20 gm/l

KCN 1.82 gm/l

NaOH 5 gm/l.

Several advantages accrue from the use of dimethylamine borane DMAB as the reducing agent. The copper is deposited from the monovalent state. Its electrical conductivity is high, making it suitable for use as an electrical conductor. The electrolyte is stable up to 90 degrees C. The boric acid or borates formed by the oxidation of the DMAB consumed in depositing copper acts as a buffer and helps stabilize the pH of the solution.

Electrolytes containing divalent copper ions tend to spontaneously decompose as soon as the borane reducing agent is added, even when the copper is complexed with ethylene diamine tetracitic acid EDTA and the solution is maintained at room temperature. In the presence of 10 mg/1 thiourea, however, the solution remains stable for up to 60 minutes and copper deposition takes place at room temperature.

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