Electrolytic copper plating bath compositions and a method for their use

1. An aqueous acidic copper plating bath for deposition of copper or copper alloys comprising at least one source of copper ions, at least one acid, and at least one guanidine compound which contains at least one unit according to formula (I)

A-D a   (I)

wherein a is an integer ranging from 1 to 40 and A represents a unit derived from a monomer according to the following formulae (A1) and/or (A2)

wherein

Y and Y′ are each individually selected from the group consisting of CH 2 , O and S;

R 1 is an organic residue selected from the group consisting of hydrogen, alkyl, aryl and alkaryl;

R 2 is an organic residue selected from the group consisting of hydrogen, alkyl, aryl and alkaryl;

R 3 , R 4 , R 5 and R 6 are each organic residues independently from each other selected from the group consisting of hydrogen, alkyl, aryl and alkaryl;

b and b′ are integers each individually and independently from each other ranging from 0 to 6;

c and c′ are integers each individually and independently from each other ranging from 1 to 6;

d and d′ are integers each individually and independently from each other ranging from 0 to 6;

e and e′ are integers each individually and independently from each other ranging from 0 to 6;

D is a divalent residue and is selected from the group consisting of

—Z 1 —[Z 2 —O] g —Z 3 —, —[Z 4 —O] h —Z 5 —, and —CH 2 —CH(OH)—Z 6 —[Z 7 —O] i —Z 8 —CH(OH)—CH 2 —;

wherein

Z 1 is an alkylene group with 1 to 6 carbon atoms;

Z 2 is selected from the group consisting of alkylene group with 1 to 6 carbon atoms, aryl-substituted alkylene groups whereby the alkylene group comprises 1 to 6 carbon atoms and mixtures of the aforementioned;

Z 3 is an alkylene group with 1 to 3 carbon atoms;

Z 4 is selected from the group consisting of alkylene group with 1 to 6 carbon atoms, aryl-substituted alkylene groups whereby the alkylene group comprises 1 to 6 carbon atoms and mixtures of the aforementioned;

Z 5 is an alkylene group with 1 to 3 carbon atoms;

Z 6 is an alkylene group with 1 to 6 carbon atoms;

Z 7 is selected from the group consisting of alkylene group with 1 to 6 carbon atoms, aryl-substituted alkylene groups whereby the alkylene group comprises 1 to 6 carbon atoms and mixtures of the aforementioned;

Z 8 is an alkylene group with 1 to 3 carbon atoms;

g is an integer ranging from 1 to 100;

h is an integer ranging from 1 to 100;

i is an integer ranging from 1 to 100; and

wherein the individual units A are selected independently from each other, and the individual units D are selected independently from each other and the guanidine compound is linear and/or cross-linked, and

wherein the bath is free of intentionally added zinc ions.

2. The aqueous acidic copper plating bath according to claim 1 characterised in that the guanidine compound comprises one or more units according to formula (I) and one or more of terminating groups P 1 and/or one or more of terminating groups P 2 whereby terminating groups P 1 are bound to a unit A derived from monomers according to formulae (A1) and/or (A2) and terminating groups P 2 are bound to divalent residues D, respectively, in the unit according to formula (I) and wherein the terminating groups P 1 are selected from the group consisting of

wherein the individual groups Z 1 to Z 8 as well as g to i are selected from above-defined groups and E is a leaving group and selected from the group consisting of triflate, nonaflate, alkylsulphonate, arylsulphonate and halogenides and wherein the terminating group P 2 is selected from the group consisting of

hydroxyl group (—OH),

a unit derived from monomers according to formulae (A1) and/or (A2),

leaving group E,

wherein the individual groups E and monomers according to formulae (A1) and/or (A2) are selected from above-defined groups.

3. The aqueous acidic copper plating bath according to claim 2 characterised in that the guanidine compound consists of a unit according to formula (I) and terminating groups P 1 and/or P 2 .

4. The aqueous acidic copper plating bath according to claim 3 characterised in that

Z 2 is selected from the group consisting of ethane-1,2-diyl, propane-1,3-diyl, propane-1,2-diyl, butane-1,2-diyl, 1-phenylethane-1,2-diyl and mixtures of the aforementioned; or

Z 4 is selected from the group consisting of ethane-1,2-diyl, propane-1,3-diyl, propane-1,2-diyl, butane-1,2-diyl, 1-phenylethane-1,2-diyl and mixtures of the aforementioned; or

Z 7 is selected from the group consisting of ethane-1,2-diyl, propane-1,3-diyl, propane-1,2-diyl, butane-1,2-diyl, 1-phenylethane-1,2-diyl and mixtures of the aforementioned.

5. The aqueous acidic copper plating bath according to claim 4 characterised in that D is selected from —Z 1 —[Z 2 —O] g —Z 3 — and —[Z 4 —O] h —Z 5 —.

6. The aqueous acidic copper plating bath according to claim 2 characterised in that

Z 2 is selected from the group consisting of ethane-1,2-diyl, propane-1,3-diyl, propane-1,2-diyl, butane-1,2-diyl, 1-phenylethane-1,2-diyl and mixtures of the aforementioned; or

Z 4 is selected from the group consisting of ethane-1,2-diyl, propane-1,3-diyl, propane-1,2-diyl, butane-1,2-diyl, 1-phenylethane-1,2-diyl and mixtures of the aforementioned; or

Z 7 is selected from the group consisting of ethane-1,2-diyl, propane-1,3-diyl, propane-1,2-diyl, butane-1,2-diyl, 1-phenylethane-1,2-diyl and mixtures of the aforementioned.

7. The aqueous acidic copper plating bath according to claim 1 characterised in that the guanidine compound consists of a unit according to formula (I) and terminating groups P 1 and/or P 2 .

8. The aqueous acidic copper plating bath according to claim 7 characterised in that:

Z 2 is selected from the group consisting of ethane-1,2-diyl, propane-1,3-diyl, propane-1,2-diyl, butane-1,2-diyl, 1-phenylethane-1,2-diyl and mixtures of the aforementioned; or

Z 4 is selected from the group consisting of ethane-1,2-diyl, propane-1,3-diyl, propane-1,2-diyl, butane-1,2-diyl, 1-phenylethane-1,2-diyl and mixtures of the aforementioned; or

Z 7 is selected from the group consisting of ethane-1,2-diyl, propane-1,3-diyl, propane-1,2-diyl, butane-1,2-diyl, 1-phenylethane-1,2-diyl and mixtures of the aforementioned.

9. The aqueous acidic copper plating bath according to claim 1 characterised in that

Z 2 is selected from the group consisting of ethane-1,2-diyl, propane-1,3-diyl, propane-1,2-diyl, butane-1,2-diyl, 1-phenylethane-1,2-diyl and mixtures of the aforementioned; or

Z 4 is selected from the group consisting of ethane-1,2-diyl, propane-1,3-diyl, propane-1,2-diyl, butane-1,2-diyl, 1-phenylethane-1,2-diyl and mixtures of the aforementioned; or

Z 7 is selected from the group consisting of ethane-1,2-diyl, propane-1,3-diyl, propane-1,2-diyl, butane-1,2-diyl, 1-phenylethane-1,2-diyl and mixtures of the aforementioned.

10. The aqueous acidic copper plating bath according to claim 1 characterised in that

Z 1 is an alkylene group with 2 to 3 carbon atoms;

Z 3 is an alkylene group with 2 to 3 carbon atoms;

Z 5 is an alkylene group with 2 to 3 carbon atoms;

Z 6 is an alkylene group with 2 to 3 carbon atoms;

g is an integer ranging from 1 to 20;

h is an integer ranging from 1 to 20; or

i is an integer ranging from 1 to 20.

11. The aqueous acidic copper plating bath according to claim 1 characterised in that D is selected from —Z 1 —[Z 2 —O] g —Z 3 — and —[Z 4 —O] h —Z 5 —.

12. The aqueous acidic copper plating bath according to claim 1 characterised in that a is an integer ranging from 2 to 30

b, b′, e and e′ are integers each individually and independently from each other ranging from 1 to 2,

c and c′ are integers each individually and independently from each other ranging from 1 to 3;

d and d′ are integers each individually ranging from 0 to 3,

c, c′, d and d′ are selected with the proviso that the sum of c+d and c′+d′ each ranges from 2 to 5.

13. The aqueous acidic copper plating bath according to claim 1 characterised in that the guanidine compounds have a weight average molecular mass M W of 500 to 50000 Da.

14. The aqueous acidic copper plating bath according to claim 13 characterised in that the guanidine compounds have a weight average molecular mass M W of 1100 to 3000 Da.

15. The aqueous acidic copper plating bath according to claim 1 characterised in that the concentration of the at least one guanidine compound in the aqueous acidic copper plating bath ranges from 0.01 mg/l to 1000 mg/l.

16. The aqueous acidic copper plating bath according to claim 1 characterised in that the concentration of the at least one guanidine compound in the aqueous acidic copper plating bath ranges from 0.1 mg/l to 100 mg/l.

17. The aqueous acidic copper plating bath according to claim 1 characterised in that the aqueous acidic copper plating bath comprises at least one further source of reducible metal ions selected from the group consisting of sources of gold ions, sources of tin ions, sources of silver ions, and sources of palladium ions.

18. The aqueous acidic copper plating bath according to claim 17 characterised in that the total amount of further sources of reducible metal ions is comprised in an amount of up to 50 wt.-% in relation to the amount of copper ions.

19. The aqueous acidic copper plating bath according to claim 1 characterised in that the aqueous acidic copper plating bath comprises no intentionally added further source of reducible metal ions.

20. A method for deposition of copper or copper alloy onto a substrate comprising, in this order, the steps

a. providing a substrate,

b. contacting the substrate with the aqueous acidic copper plating bath according to claim 1 , and

c. applying an electrical current between the substrate and at least one anode,

for a time sufficient to deposit copper or copper alloy on at least a portion of the surface of a substrate.