Electroless copper deposition process having faster plating rates

In a method for electrolessly depositing copper from an electroless copper deposition solution which comprises copper ions, a complexing agent for copper ions, a reducing agent and a pH adjustor and which is characterized by a plating rate which first increases and passes through a peak plating rate and then decreases as a function of pH above 10, the improvement for depositing at a rate greater than about 7 micrometers of electroless copper per hour in a bath composition operated at a temperature of about 25.degree. C. to about 35.degree. C. to a rate greater than 19 micrometers of electroless copper per hour in a bath composition operated at a temperature above 35.degree. C., a coherent, structurally stable thin film of electroless copper adherent to a substratum, comprising:

• (A) including within the electroless copper deposition solution an accelerating agent which contains a delocalized pi-bond and is selected from among
• (a) heterocyclic aromatic nitrogen and and sulfur compounds,
• (b) non-aromatic nitrogen compounds having at least one delocalized pi-bond,
• (c) aromatic amines, and
• (d) mixtures of any of the foregoing;
• (B) contacting the electroless copper deposition solution with a substratum sensitive to the deposition of electroless copper;
• and
• (C) while operating the electroless copper deposition solution at a pH above 10, regulating the pH thereabove and the amount of said accelerating agent therein to maintain a deposition within said rate, to thereby achieve a coherent, structurally stable thin film of electroless copper adhered to the surface of said substratum.