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Electroless Copper Initiation "Take" Improvement by the Addition of Trace Metal Ions

IP.com Disclosure Number: IPCOM000059687D
Original Publication Date: 1986-Jan-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 1 page(s) / 13K

Publishing Venue

IBM

Related People

Bindra, P: AUTHOR [+3]

Abstract

To initiate electroless copper plating a catalyst is needed. Palladium (Pd) is the most commonly used metal for initiation and is deposited in a two-step operation: Sn2+ is adsorbed onto the non-conductive substrate from a SnCl2 solution, followed by the reduction of Pd2+ . Sn2+ is oxidized to Sn4+ in the reaction. The addition of other ions to the Pd Cl2 activation solution can affect the reducing agents' catalytic activity. The addition of parts per million (ppm) amounts of Ag+ to the Pd C12 solution prior to electroless plating increases the amount of copper deposited in a given time. The Ag+ may be added as Ag NO3 . The addition of Ni+ has also been shown to retard the initiation electroless copper plating.

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Electroless Copper Initiation "Take" Improvement by the Addition of Trace Metal Ions

To initiate electroless copper plating a catalyst is needed. Palladium (Pd) is the most commonly used metal for initiation and is deposited in a two-step operation: Sn2+ is adsorbed onto the non-conductive substrate from a SnCl2 solution, followed by the reduction of Pd2+ . Sn2+ is oxidized to Sn4+ in the reaction. The addition of other ions to the Pd Cl2 activation solution can affect the reducing agents' catalytic activity. The addition of parts per million (ppm) amounts of Ag+ to the Pd C12 solution prior to electroless plating increases the amount of copper deposited in a given time. The Ag+ may be added as Ag NO3 . The addition of Ni+ has also been shown to retard the initiation electroless copper plating. The addition of copper ions to Pd activating solutions produces a superior Pd catalyst for electroless metal plating. A mixed Pd Cl2/Sn Cl2 solution containing hydrochloric acid is most commonly used to catalyze metallic and nonmetallic substrates for electroless metal deposition. In such a system, the driving force for the formation of Pd crystallites is fixed. Consequently, the resultant catalyst is characterized by crystallites of a fixed size and number. Experimental data obtained using well known electrochemical techniques have indicated that the addition of trace quantities of copper ions to the activating solution enhances the nucleation rate quite substantially. Studies of galvanostatic transients obtained for the deposition of palladium, with and without copper ions being present in the activating solution, make it clear that the addition of copper ions lowers the polarization necessary for Pd dep...