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Additive for Copper Pyrophosphate Electroplating Solution

IP.com Disclosure Number: IPCOM000092522D
Original Publication Date: 1966-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Phillips, SL: AUTHOR

Abstract

Operation of a copper-pyrophosphate plating bath requires that a closely controlled pH of about 7.9 to about 8.5 be maintained. In preparing the initial plating solution, the pH is adjusted to the required range by the addition of either potassium hydroxide or tetraphosphoric acid H(6)P(4)O(13).

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Additive for Copper Pyrophosphate Electroplating Solution

Operation of a copper-pyrophosphate plating bath requires that a closely controlled pH of about 7.9 to about 8.5 be maintained. In preparing the initial plating solution, the pH is adjusted to the required range by the addition of either potassium hydroxide or tetraphosphoric acid H(6)P(4)O(13).

During the operation of the plating bath the pH and ammonia content of the bath are maintained. The use of urea H(2)NCONH(2) as a major constituent of the original plating solution results in the production of the necessary ammonia and gives the required pH control. Urea undergoes the hydrolysis reaction: H(2)NCONH(2) + H(2)O-->2NH(3) + CO(2) to generate ammonia and carbon dioxide. The ammonia then undergoes further reaction with water to form ammonium hydroxide. The hydrolysis reaction is generally temperature dependent and increases as temperature increases. Therefore, the rate of hydrolysis and the dependent rate of generation of ammonia can be closely controlled by temperature.

Urea can be used in a similar manner to control the pH of solutions other than copper-pyrophosphate.

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