Method for preparing substrates for deposition of metal seed from an organometallic vapor for subsequent electroless metallization

DETAILED DESCRIPTION The method of the present invention, in its broadest aspect, comprises the steps of forming active chemical sites adhering to a substrate surface and chemically reacting with these sites volatile organometallic compounds.
The substrate with chemically active sites is exposed to a vapor of the volatile organometallic compound for a time long enough for the organometallic compound to decompose into a species of its constituent metal by reacting with the chemically active site.
Since the chemically active sites adhere to the substrate surface, the chemical species of the constituent metal also adheres to the substrate surface.
As used herein, the species of the constituent metal of the compound means: (1) a chemical compound of the constituent metal; (2) the constituent metal in a nonzero oxidation state; or (3) the constituent metal in the zero oxidation state.
In accordance with a more particular aspect of the present invention, the metallic chemical species, if not the zero oxidation state of the constituent metal, is then transformed into the zero oxidation state of the constituent metal which is bound to the substrate surface.
Such a transformation can be accomplished by thermal decomposition, by chemical reduction, by exposing the substrate to atmospheric oxygen, and by exposure of a heated substrate to atmospheric oxygen.
The zero oxidation state metal constituent adhering to the substrate surface is useful as a seed layer for electorless deposition by conventional means of the same metal or another metal.
In accordance with another more particular aspect of the invention, after the chemically active sites have been formed on the substrate surface, a resist-type material such as a photoresist can be deposited on the substrate and patterned to expose these sites in selected locations.
The substrate is then exposed to the vapor of the organometallic compound which selectively reacts with the exposed chemically active sites on the substrate surface.
In these regions the organometallic compound decomposes to a species of the constituent metal which is then transformed into the constituent metal that can act as selective seed layer for electrolessly depositing the same or another metal