Tin-silver solder bumping in electronics manufacture
View Patent ↗A process for forming a solder bump on an under bump metal structure in the manufacture of a microelectronic device comprising exposing the under bump metal structure to an electrolytic bath comprising a source of Sn 2+ ions, a source of Ag + ions, a thiourea compound and/or a quaternary ammonium surfactant; and supplying an external source of electrons to the electrolytic bath to deposit a Sn—Ag alloy onto the under bump metal structure.
1. An electroplating composition for plating a Sn—Ag solder bump comprising:
a source of Sn 2+ ions;
a source of Ag + ions;
a N-allyl-thiourea compound having a formula (I):
wherein R 2 , R 3 , R 4 , R 5 , and R 6 are each independently hydrogen, hydroxyl, hydrocarbyl, substituted hydrocarbyl, heterocycloalkyl, substituted heterocycloalkyl, alkoxy, substituted alkoxy, aryl, substituted aryl, heteroaryl, or substituted heteroaryl and R 1 is —CH 2 CH 2 OH (β-hydroxyethyl); and
a quaternary ammonium surfactant.
2. A process for forming a solder bump on an under bump metal structure in the manufacture of a microelectronic device, the process comprising:
exposing the under bump metal structure to an electrolytic bath comprising a source of Sn 2+ ions, a source of Ag + ions, and an N-allyl-thiourea compound having a formula (I):
wherein R 2 , R 3 , R 4 , R 5 , and R 6 are each independently hydrogen, hydroxyl, hydrocarbyl, substituted hydrocarbyl, heterocycloalkyl, substituted heterocycloalkyl, alkoxy, substituted alkoxy, aryl, substituted aryl, heteroaryl, or substituted heteroaryl and R 1 is —CH 2 CH 2 OH (β-hydroxyethyl); and
supplying an external source of electrons to the electrolytic bath to deposit a Sn—Ag alloy onto the under bump metal structure.
3. The process of claim 2 wherein R 2 , R 3 , R 4 , R 5 , and R 6 are hydrogen.
4. The process of claim 2 wherein the N-allyl-thiourea compound has a concentration between about 0.5 g/L and about 24 g/L.
5. The process of claim 2 wherein the N-allyl-thiourea compound has a concentration between about 1 g/L and about 8 g/L.
6. The process of claim 2 wherein the supplying the external source of electrons employs a current density of at least about 8 A/dm 2 .
7. The process of claim 2 wherein the supplying the external source of electrons employs a current density between about 8 A/dm 2 and about 20 A/dm 2 .
8. The process of claim 2 wherein the electrolytic bath further comprises an alkyl dimethyl benzyl ammonium surfactant.
9. The process of claim 2 wherein the electrolytic bath further comprises a β-naphthol derivative.
10. The process of claim 2 wherein the electrolytic bath further comprises hydroquinone.
11. The process of claim 2 wherein the electrolytic bath further comprises a quaternary ammonium surfactant and a β-naphthol derivative.
12. The process of claim 2 wherein the electrolytic bath further comprises a quaternary ammonium surfactant, a β-naphthol derivative, and hydroquinone.
13. The process of claim 2 wherein the electrolytic bath comprises:
between about 0.5 g/L and about 24 g/L of the N-allyl-thiourea compound;
the Sn 2+ ions in a concentration between about 10 g/L and about 100 g/L; and
the Ag + ions in a concentration between about 0.1 g/L and about 1.5 g/L.
14. The process of claim 13 wherein the supplying the external source of electrons employs a current density between about 8 A/dm 2 and about 20 A/dm 2 .
15. The process of claim 2 wherein the electrolytic bath further comprises a β-naphtholethoxylate comprising between 8 and 16 ethylene oxide monomer units.
16. A process for forming a solder bump on an under bump metal structure in the manufacture of a microelectronic device, the process comprising:
exposing the under bump metal structure to an electrolytic bath comprising a source of Sn 2+ ions, a source of Ag + ions, and an N-allyl-thiourea compound having a formula (I):
wherein R 2 , R 3 , R 4 , R 5 , and R 6 are each independently hydrogen, hydroxyl, hydrocarbyl, substituted hydrocarbyl, heterocycloalkyl, substituted heterocycloalkyl, alkoxy, substituted alkoxy, aryl, substituted aryl, heteroaryl, or substituted heteroaryl and R 1 is —CH 2 CH 2 OH (β-hydroxyethyl), and a quaternary ammonium surfactant; and
supplying an external source of electrons to the electrolytic bath to deposit a Sn—Ag alloy onto the under bump metal structure.
17. A process for forming a solder bump on an under bump metal structure in the manufacture of a microelectronic device, the process comprising:
exposing the under bump metal structure to an electrolytic bath comprising a source of Sn 2+ ions, a source of Ag + ions, an N-allyl-thiourea compound having a formula (I):
wherein R 2 , R 3 , R 4 , R 5 , and R 6 are each independently hydrogen, hydroxyl, hydrocarbyl, substituted hydrocarbyl, heterocycloalkyl, substituted heterocycloalkyl, alkoxy, substituted alkoxy, aryl, substituted aryl, heteroaryl, or substituted heteroaryl and R 1 is —CH 2 CH 2 OH (β-hydroxyethyl), lauryl benzyl dimethyl ammonium chloride and myristyl benzyl dimethyl ammonium chloride; and
supplying an external source of electrons to the electrolytic bath to deposit a Sn—Ag alloy onto the under bump metal structure.
18. A process for forming a solder bump on an under bump metal structure in the manufacture of a microelectronic device, the process comprising:
exposing the under bump metal structure to an electrolytic bath comprising a source of Sn 2+ ions, a source of Ag + ions, and an N-allyl-thiourea compound having a formula (I):
wherein R 2 , R 3 , R 4 , R 5 , and R 6 are each independently hydrogen, hydroxyl, hydrocarbyl, substituted hydrocarbyl, heterocycloalkyl, substituted heterocycloalkyl, alkoxy, substituted alkoxy, aryl, substituted aryl, heteroaryl, or substituted heteroaryl and R 1 is —CH 2 CH 2 OH (β-hydroxyethyl), and a sulfonated β-naphthol propoxylate/ethoxylate; and
supplying an external source of electrons to the electrolytic bath to deposit a Sn—Ag alloy onto the under bump metal structure.
19. A process for forming a solder bump on an under bump metal structure in the manufacture of a microelectronic device, the process comprising:
exposing the under bump metal structure to an electrolytic bath comprising a source of Sn 2+ ions, a source of Ag + ions, and a quaternary ammonium surfactant wherein the quaternary ammonium surfactant comprises lauryl benzyl dimethyl ammonium chloride and myristyl benzyl dimethyl ammonium chloride; and
supplying an external source of electrons to the electrolytic bath to deposit a Sn—Ag alloy onto the under bump metal structure.
20. The process of claim 19 further comprising a N-allyl-thiourea compound.
21. The process of claim 20 wherein the N-allyl-thiourea compound is N-allyl-thiourea.
22. The process of claim 20 wherein the N-allyl-thiourea compound is N-allyl-N′-β-hydroxyethyl-thiourea.
23. The process of claim 19 wherein the supplying the external source of electrons employs a current density between about 8 A/dm 2 and about 20 A/dm 2 .
24. The process of claim 19 wherein the electrolytic bath further comprises a β-naphthol derivative.
25. The process of claim 19 wherein the electrolytic bath further comprises a β-naphtholethoxylate, a sulfonated β-naphthol propoxylate/ethoxylate, or a combination thereof.
26. The process of claim 19 wherein the electrolytic bath further comprises hydroquinone.
27. The process of claim 19 wherein the electrolytic bath further comprises an N-allyl-thiourea compound and a β-naphthol derivative.
28. The process of claim 19 wherein the electrolytic bath further comprises an N-allyl-thiourea compound, a β-naphthol derivative, and hydroquinone.