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Browse Prior Art Database

Silicon Based Seeding of Electroless Metal Deposition

IP.com Disclosure Number: IPCOM000040540D
Original Publication Date: 1987-Nov-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 3 page(s) / 38K

Publishing Venue

IBM

Related People

Bindra, P: AUTHOR [+4]

Abstract

Electroless plating baths require surface catalyzation of a plating object for acceptance of metal. This surface catalyzation can be accomplished in a single-step process that involves the surface adsorption of Pd/Sn alloy. Surfaces can be chemically treated to be receptive to uniform metal deposition from a variety of electroless plating solutions. A method for activating non-conducting surfaces by utilizing the concept of currentless metal deposition from metal ions in solution onto particulate or sputtered silicon is accomplished as follows. The energy level diagram for n- and p-type semiconductors and an electrolyte prior to contact is shown in the drawing, where the energy levels are described in volts vs. a reference electrode.

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Silicon Based Seeding of Electroless Metal Deposition

Electroless plating baths require surface catalyzation of a plating object for acceptance of metal. This surface catalyzation can be accomplished in a single-step process that involves the surface adsorption of Pd/Sn alloy. Surfaces can be chemically treated to be receptive to uniform metal deposition from a variety of electroless plating solutions. A method for activating non-conducting surfaces by utilizing the concept of currentless metal deposition from metal ions in solution onto particulate or sputtered silicon is accomplished as follows. The energy level diagram for n- and p-type semiconductors and an electrolyte prior to contact is shown in the drawing, where the energy levels are described in volts vs. a reference electrode. Ef is the Fermi level of the semiconductor, Ecb and Evb are the conduction and valence band positions, respectively, Ebg is the semiconductor bandgap and Mn+/M and Nz+/N are the redox potentials of two metal ion/metal systems in the electrolyte. Redox potentials in electrolytes can be shown to be equivalent to Fermi levels in metals or semiconductors. When the n-type semiconductor is immersed in an electrolyte containing the Mn+/M redox system, there is equilibration of the two Fermi levels by appropriate charge transfer. The thermodynamic equilibration is achieved by spontaneous hole injection from metal ions into the valence band of the semiconductor. This is currentless deposition and, as such, is possible only if there is a counter anodic reaction. If the standard potential for anodic dissolution of the semiconductor Eod is more negative than Eredox then the anodic reaction is the dissolution of the semiconductor (e.g., formation of SiO2 in case of Si). If Eod is more positive than Eredox, then the spontaneous metal deposition reaction is accompanied by some anodic reactions. When a p-type semiconductor is immersed in electrolyte containing the Nz+/N redox system, metal deposition occurs via spontaneous minori...