Bonding methods for light emitting diodes
Disclosed herein are techniques for bonding LED components. According to certain embodiments, a first component is bonded to a second component using dielectric bonding and metal bonding. The first component includes an active light emitting layer between oppositely doped semiconductor layers. The second component includes a substrate having a different thermal expansion coefficient than the first component. First contacts of the first component are aligned to second contacts of the second component. A dielectric material of the first component is then bonded to a dielectric material of the second component. The metal bonding is performed between the first contacts and the second contacts, after the dielectric bonding, and using annealing. The bonded structure has a concave or convex shape before the metal bonding. Run-out between the first contacts and the second contacts is compensated through temperature-induced changes in a curvature of the bonded structure during the metal bonding.
1. A method comprising:
aligning first contacts of a first component with second contacts of a second component, wherein:
the first component comprises a first semiconductor layer, a second semiconductor layer, and an active light emitting layer between the first semiconductor layer and the second semiconductor layer,
the first semiconductor layer and the second semiconductor layer are oppositely doped, and
the second component comprises a substrate having a different thermal expansion coefficient than the first component;
bonding the first component to the second component to form a bonded structure, the bonding comprising:
dielectric bonding a first dielectric material of the first component to a second dielectric material of the second component, and
metal bonding the first contacts to the second contacts using annealing after the dielectric bonding, wherein the bonded structure has a concave or convex shape before the metal bonding; and
compensating a run-out between the first contacts and the second contacts, through temperature-induced changes in a curvature of the bonded structure during the metal bonding.
2. The method of claim 1 , wherein the bonded structure is substantially flat after being cooled to a temperature of 20° C.
3. The method of claim 1 , further comprising:
forming the bonded structure into a concave shape before the metal bonding, wherein the bonded structure becomes less concave when heated during the annealing.
4. The method of claim 3 , wherein the bonded structure is less concave, but not completely flat, when heated to a temperature at which the first contacts and the second contacts become bonded.
5. The method of claim 3 , wherein the bonded structure is formed into the concave shape after the dielectric bonding.
6. The method of claim 1 , further comprising:
forming the bonded structure into a convex shape before the metal bonding, wherein the bonded structure becomes less convex when heated during the annealing.
7. The method of claim 6 , wherein the bonded structure is less convex, but not completely flat, when heated to a temperature at which the first contacts and the second contacts become bonded.
8. The method of claim 6 , wherein the bonded structure is formed into the convex shape after the dielectric bonding.
9. The method of claim 1 , wherein the first component comprises one or more semiconductor layers that change curvature during the metal bonding.
10. The method of claim 9 , wherein the one or more semiconductor layers of the first component comprise a doped buffer layer, the active light emitting layer, or both the doped buffer layer and the active light emitting layer.
11. The method of claim 10 , wherein the one or more semiconductor layers of the first component comprise an n-GaN buffer layer.
12. The method of claim 10 , wherein the one or more semiconductor layers of the first component comprise p-GaN quantum wells in the active light emitting layer.
13. The method of claim 1 , further comprising:
controlling an annealing temperature of the first component and an annealing temperature of the second component independently in accordance with predetermined vertical and lateral temperature profiles.
14. The method of claim 13 , wherein the vertical and lateral temperature profiles are determined using a finite element method based simulation.
15. The method of claim 13 , wherein the metal bonding comprises using a laser to perform local area heating and annealing.
16. The method of claim 1 , wherein:
the first component further comprises a second substrate and a buffer layer between the first semiconductor layer and the second substrate;
the first dielectric material forms a dielectric layer having a first side nearer to the first semiconductor layer and a second side nearer to the second semiconductor layer, and
the first contacts are located on the second side of the dielectric layer.
17. The method of claim 16 , wherein the first semiconductor layer is an n-type semiconductor layer, and wherein the second semiconductor layer is a p-type semiconductor layer.
18. The method of claim 16 , further comprising:
removing the second substrate after first component has been bonded to the second component, wherein the first semiconductor layer is an n-type semiconductor layer; and
performing n-side processing on the bonded structure after the second substrate has been removed.
19. The method of claim 1 , wherein the second component comprises driver circuits for light emitting diodes in the first component.
20. The method of claim 19 , wherein the driver circuits are passive or active matrix integrated circuits within a silicon layer of the substrate.