International Business Machines Corporation

Gerald L Ballard

John Gerard Gaudiello

Voya Rista Markovich

Robert Douglas Edwards

Gold is deposited on a copper base defining electrical circuit features disposed on a substrate containing a palladium seeder, by initially treating the substrate with an alkaline cleaner, followed by treating the substrate with sodium persulfate, and subsequently treating the substrate with a diluted sulfuric acid solution. The substrate is rinsed between each one of the treatments, and after the final rinse following treatment with diluted sulfuric acid, the substrate is immersed in a gold deposition solution whereby gold is deposited on the exposed surfaces of the copper circuit features on a substrate. The process embodying the present invention provides a method for depositing gold on high density copper conductor lines or pads, even in areas of the surface in which the conductors are spaced apart 2.0 mil or less, without cleaning or removing the palladium seed from the surface.

Method for electroless gold deposition in the presence of a palladium seeder and article produced thereby

Method for electroless gold deposition in the presence of a palladium

An electroless metal plating bath composition, a corresponding method for electrolessly depositing a metal onto a substrate surface, as well as the resulting, metallized substrate, are disclosed. The inventive bath composition includes water, a soluble source of the metal ions it is desired to chemically reduce at, and deposit onto, the substrate surface of interest, and a complexing agent for the metal ions. In addition, the bath composition includes a soluble source of any one or more of a select group of what are termed mediator ions, which group includes palladium (Pd), platinum (Pt), silver (Ag), ruthenium (Ru), iridium (Ir), osmium (Os) and rhodium (Rh) ions, as well as a complexing agent for the mediator ions. Moreover, the bath composition includes a chemical reducing agent, which primarily serves to chemically reduce the mediator ions at the substrate surface of interest. Significantly, by using an appropriate ratio of the concentration of the metal ions in solution to the concentration of the mediator ions in solution, and depending upon which mediator ions are used, the inventive bath composition serves to electrolessly deposit the metal of interest onto the substrate surface of interest, with the resulting deposited metal containing less than or equal to about 3.0 atomic percent, or less than or equal to about 2.0 atomic percent, or even less than or equal to about 1.0 atomic percent, of the corresponding mediator metal.

Method for electrolessly depositing a metal onto a substrate using

Metallized substrate

Plating bath, and corresponding method, for electrolessly depositing a

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Apalachin, NY, United States of America

Gerald L Ballard