Nickel tin bonding system with barrier layer for semiconductor wafers and devices
View Patent ↗A light emitting diode structure is disclosed that includes a light emitting active portion formed of epitaxial layers and carrier substrate supporting the active portion. A bonding metal system that predominates in nickel and tin joins the active portion to the carrier substrate. At least one titanium adhesion layer is between the active portion and the carrier substrate and a platinum barrier layer is between the nickel-tin bonding system and the titanium adhesion layer. The platinum layer has a thickness sufficient to substantially prevent tin in the nickel tin bonding system from migrating into or through the titanium adhesion layer.
1. A light emitting diode structure comprising:
a light emitting active portion formed of epitaxial layers;
a carrier substrate for supporting said active portion;
a bonding metal system that predominates in nickel and tin joining said active portion to said carrier substrate; and
at least one barrier layer adjacent said bonding metal system that predominates in nickel and tin, said barrier layer having a composition and a thickness sufficient to substantially prevent tin in said bonding metal system that predominates in nickel and tin from migrating through said barrier layer;
wherein said bonding metal system includes gold in an amount greater than 0.3 percent and less than 36 percent by weight of said bonding metal system.
2. A light emitting diode structure according to claim 1 wherein said barrier layer is platinum.
3. A light emitting diode structure according to claim 2 further comprising at least one adhesion layer between said active portion and said platinum barrier layer.
4. A light emitting diode structure according to claim 3 wherein said adhesion layer comprises titanium.
5. A light emitting diode structure according to claim 4 further comprising:
a second titanium adhesion layer between said bonding metal system and said carrier substrate; and
a second platinum barrier layer between said second titanium adhesion layer and said bonding metal system.
6. A light emitting diode structure according to claim 2 wherein said bonding metal system comprises a metal alloy that is more than 85 percent nickel and tin.
7. A light emitting diode structure according to claim 1 wherein said barrier layer can form intermetallic compounds with tin that are thermally stable within the temperature range of between about 240° and 350° C.
8. A light emitting diode structure according to claim 1 wherein said bonding metal system is a metal alloy that contains gold in an amount of less than 20 percent by weight.
9. A light emitting diode structure according to claim 1 wherein said light emitting active portion is formed from the Group III nitride material system.
10. A light emitting diode structure according to claim 9 wherein said active portion comprises gallium nitride.
11. A light emitting diode structure according to claim 1 wherein said carrier substrate is selected from the group consisting of aluminum, copper, silicon and silicon carbide.
12. A light emitting diode structure according to claim 1 wherein said bonding metal system is less than 6 microns thick.
13. A light emitting diode structure according to claim 1 wherein said bonding metal system is less than 3 microns thick.
14. A light emitting diode structure comprising:
a light emitting active portion formed of epitaxial layers;
a carrier substrate for supporting said active portion;
a bonding metal system that predominates in nickel and tin joining said active portion to said carrier substrate; and
a barrier layer between said bonding metal system and said epitaxial layers, said barrier layer being formed of a material and having a thickness sufficient to substantially preclude the formation or migration of free metals or alloys that have melting points lower than 300° C.;
wherein said bonding metal system includes gold in an amount greater than 0.3 percent and less than 36 percent by weight of said bonding metal system.
15. A light emitting diode structure according claim 14 wherein said barrier layer includes platinum.
16. A light emitting diode structure according to claim 15 and further comprising an adhesion layer between said bonding metal system and said light emitting active portion and with said platinum barrier layer between said adhesion layer and said bonding metal system.
17. A light emitting diode according to claim 16 wherein said adhesion layer includes titanium.
18. A light emitting diode structure according to claim 14 wherein said bonding metal system is less than 6 microns thick.
19. A light emitting diode structure according to claim 14 wherein said bonding metal system is less than 3 microns thick.
20. A light emitting diode structure according to claim 14 , comprising a lead frame attached to said carrier substrate with a solder composition.