Copper electrodeposition in microelectronics
View Patent ↗An electrolytic plating method and composition for electrolytically plating Cu onto a semiconductor integrated circuit substrate having submicron-sized interconnect features. The composition comprises a source of Cu ions and a suppressor compound comprising polyether groups. The method involves superfilling by rapid bottom-up deposition at a superfill speed by which Cu deposition in a vertical direction from the bottoms of the features to the top openings of the features is substantially greater than Cu deposition on the side walls.
1. An electrolytic plating composition for electrolytically plating Cu onto a semiconductor integrated circuit substrate having a planar plating surface and submicron-sized interconnect features by immersion of the semiconductor integrated circuit substrate into the electrolytic solution, the composition comprising:
a source of Cu ions in an amount sufficient to electrolytically deposit Cu onto the substrate and into the electrical interconnect features; and
a suppressor comprising a compound selected from the group consisting of:
(i) a first suppressor compound comprising a polyether group bonded to a nitrogen-containing species, wherein the polyether group comprises a combination of propylene oxide (PO) repeat units and ethylene oxide (EO) repeat units present in a PO:EO ratio between about 1:9 and about 9:1, and wherein the molecular weight of the first suppressor compound is between about 1000 and about 3600 g/mol;
(ii) a second suppressor compound comprising a polyether group bonded to a nitrogen-containing species, wherein the polyether group comprises a combination of propylene oxide (PO) repeat units and ethylene oxide (EO) repeat units present in a PO:EO ratio between about 1:9 and about 9:1, wherein the molecular weight of the second suppressor compound is between about 1000 and about 30,000 g/mol, and wherein the second suppressor compound further comprises a capping moiety selected from the group consisting of an alkyl group or a block polymer comprising propylene oxide repeat units;
(iii) a third suppressor compound comprising a polyether group bonded to a nitrogen-containing species, wherein the polyether group comprises a combination of propylene oxide (PO) repeat units and ethylene oxide (EO) repeat units present in a PO:EO ratio between about 1:9 and about 9:1, wherein the nitrogen-containing species is an alkylether amine, and wherein the molecular weight of the third suppressor compound is between about 1000 and about 30,000 g/mol; and
(iv) a fourth suppressor compound comprising a polyether group bonded to a nitrogen-containing species, wherein the polyether group comprises a combination of propylene oxide (PO) repeat units and ethylene oxide (EO) repeat units present in a PO:EO ratio between about 1:9 and about 9:1, wherein the molecular weight of the fourth suppressor compound is between about 1000 and about 30,000 g/mol, and wherein a nitrogen in the nitrogen-containing species is a quaternary amine;
(v) a fifth suppressor compound comprising a polyether group bonded to a nitrogen-containing species, wherein the polyether group comprises a combination of propylene oxide (PO) repeat units and ethylene oxide (EO) repeat units present in a PO:EO ratio between about 1:9 and about 9:1, wherein the molecular weight of the fifth suppressor compound is between about 1000 and about 30,000 g/mol, and wherein the composition comprises less than about 30 g/L acid when the fifth suppressor is selected;
(vi) a sixth suppressor compound comprising a polyether group bonded to a nitrogen-containing species, wherein the polyether group comprises a combination of propylene oxide (PO) repeat units and ethylene oxide (EO) repeat units present in a PO:EO ratio between about 1:9 and about 9:1, wherein the molecular weight of the sixth suppressor compound is between about 1000 and about 30,000 g/mol, and wherein the composition comprises between about 4 g/L and about 30 g/L copper ion when the sixth suppressor is selected; and
(vi) combinations thereof.
2. The electrolytic plating composition of claim 1 wherein the propylene oxide repeat units and ethylene oxide repeat units are present in a PO:EO ratio between about 2:3 and about 3:2.
3. The electrolytic plating composition of claim 1 wherein the EO and PO repeat units are arranged in a block co-polymer sequence.
4. The electrolytic plating composition of claim 2 wherein the EO and PO repeat units are arranged in a block co-polymer sequence.
5. The electrolytic plating composition of claim 1 wherein the nitrogen-containing species comprises at least one amine functional group.
6. The electrolytic plating composition of claim 5 wherein the polyether group is bonded to a nitrogen atom in the at least one amine functional group.
7. The electrolytic plating composition of claim 5 wherein the at least one amine functional group is a quaternary amine.
8. The electrolytic plating composition of claim 2 wherein the nitrogen-containing species comprises at least one amine functional group.
9. The electrolytic plating composition of claim 7 wherein the polyether group is bonded to a nitrogen atom in the at least one amine functional group.
10. The electrolytic plating composition of claim 8 wherein the at least one amine functional group is a quaternary amine.
11. The electrolytic plating composition of claim 1 wherein the nitrogen-containing species comprises between two and five amine functional groups.
12. The electrolytic plating composition of claim 2 wherein the nitrogen-containing species comprises between two and five amine functional groups.
13. The electrolytic plating composition of claim 2 wherein the nitrogen-containing species comprises a diamine.
14. The electrolytic plating composition of claim 2 wherein the nitrogen-containing species is selected from the group consisting of ethylene diamine and triethylene glycol diamine.
15. The electrolytic plating composition of claim 1 wherein the suppressor compound comprises a structure selected from the group consisting of:
and combinations thereof;
wherein
R 1 is a substituted or unsubstituted alkyl group;
R 2 is selected from the group consisting of hydrogen and alkyl group;
R 3 is a polyether comprising repeat units selected from the group consisting of ethylene oxide repeat units, propylene oxide repeat units, and a combination thereof;
and
R 4 is selected from the group consisting of hydrogen, substituted or unsubstituted alkyl group, aryl group, aralkyl, or heteroaryl group.
16. The electrolytic plating composition of claim 15 wherein the R 1 alkyl group has between 1 and 8 carbons, and R 1 is substituted with another amino group to which a polyether group is covalently bonded, the polyether comprising ethylene oxide repeat units, propylene oxide repeat units, or a combination thereof arranged in random, alternating, or block configurations.
17. The electrolytic plating composition of claim 2 wherein the polyether suppressor is present in a concentration between about 50 mg/L and about 200 mg/L.
18. The electrolytic plating composition of claim 1 wherein the polyether suppressor comprises the structure:
wherein n is between 1 and about 30 and m is between 1 and about 30.
19. The electrolytic plating composition of claim 1 wherein the polyether suppressor comprises the structure:
wherein n is between 1 and about 30 and m is between 1 and about 30.