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Complex Addition of Cobalt Ion to Electroless Cobalt Baths

IP.com Disclosure Number: IPCOM000095340D
Original Publication Date: 1965-Dec-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Alberts, GS: AUTHOR [+2]

Abstract

During the continuous deposition of cobalt from electroless cobalt baths it is desirable to maintain the reactants at a nearly fixed level to control the deposition rate. The magnetic and structural properties of the plated cobalt are affected by the deposition rate.

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Complex Addition of Cobalt Ion to Electroless Cobalt Baths

During the continuous deposition of cobalt from electroless cobalt baths it is desirable to maintain the reactants at a nearly fixed level to control the deposition rate. The magnetic and structural properties of the plated cobalt are affected by the deposition rate.

During the course of plating cobalt from an electroless bath of the cobalt cation hypophosphite anion type phosphite anions are formed. In order to avoid precipitation of slightly soluble cobalt phosphite cobalt complexing agents are normally added to the bath. A localized high concentration of cobalt cations is formed in the bath upon the addition of cobalt solutions to the bath in order to maintain the desired cobalt cation concentration. This leads to the formation of a temporary precipitate of cobalt phosphite that is likely to be and generally is, a nucleation site for unwanted cobalt-phosphorus. This leads to plate-out f cobalt- phosphorus on the sides of the plating tank or even more radical, spontaneous deposition of the cobalt from the entire bath.

In order to avoid the first link in this chain which leads to spontaneous deposition it is desirable to avoid the formation of cobalt phosphite upon the addition of cobalt cations to the bath. This is accomplished by adding the cobalt cations to the bath in a complexed form. The composition of the addition reagent can be varied substantially. For example the cobalt cation can be complexed ...