Method of forming a composite substrate
View Patent ↗In a method according to embodiments of the invention, a III-nitride layer is grown on a growth substrate. The III-nitride layer is connected to a host substrate. The growth substrate is removed. The growth substrate is a non-III-nitride material. The growth substrate has an in-plane lattice constant a substrate. The III-nitride layer has a bulk lattice constant a layer. In some embodiments, [(| a substrate−a layer|)/ a substrate]*100% is no more than 1%.
1. A method comprising:
growing a III-nitride layer on a growth substrate; wherein
the growth substrate is a non-III-nitride material;
the growth substrate has an in-plane lattice constant a substrate ;
the III-nitride layer has a bulk lattice constant a layer ; and
[(|a substrate −a layer |)/a substrate ]*100% is no more than 1%;
connecting the III-nitride layer to a host substrate; and
removing the growth substrate,
wherein growing a III-nitride layer on a growth substrate comprises growing the III-nitride layer such that a group V face of the III-nitride layer is proximate the host substrate and a group III face of the III-nitride layer is opposite the host substrate.
2. The method of claim 1 wherein the growth substrate is ScAlMgO 4 and the III-nitride layer is InGaN.
3. The method of claim 1 wherein the growth substrate is RAO 3 (MO) n , where R is selected from Sc, In, Y, and the lanthanides; A is selected from Fe (III), Ga, and Al; M is selected from Mg, Mn, Fe (II), Co, Cu, Zn and Cd; and n is an integer ≧1.
4. The method of claim 1 wherein the III-nitride layer is one of InGaN and AlInGaN.
5. The method of claim 1 wherein the III-nitride layer is In x Ga 1-x N, where 0.06≦x≦0.48.
6. The method of claim 1 wherein connecting comprises bonding through a bonding layer disposed between the III-nitride layer and the host substrate.
7. The method of claim 6 wherein the bonding layer is one of a non-III-nitride material, SiO x , and SiN x .
8. The method of claim 6 wherein:
the III-nitride layer is InGaN;
the bonding layer is SiO x ; and
the host substrate is sapphire.
9. The method of claim 1 further comprising growing on the III-nitride layer a structure comprising a III-nitride light emitting layer disposed between an n-type region and a p-type region.
10. The method of claim 9 further comprising removing the host substrate after growing a structure comprising a III-nitride light emitting layer disposed between an n-type region and a p-type region.
11. The method of claim 1 further comprising forming a zone of weakness in the growth substrate or at an interface between the growth substrate and the III-nitride layer, wherein removing the growth substrate comprises separating the III-nitride layer from the growth substrate at the zone of weakness.
12. The method of claim 11 wherein the zone of weakness comprises a region implanted with one of H atoms and N atoms.
13. The method of claim 11 wherein the zone of weakness comprises a plurality of micron scale crystal defects or voids created by irradiation with focused laser beams.
14. The method of claim 1 wherein the host substrate is sapphire.
15. The method of claim 1 wherein the III-nitride layer is grown on a surface of the growth substrate that is misoriented from a (0001) plane of the growth substrate by between −10 and 10 degrees.
16. The method of claim 1 wherein removing comprises removing by a mechanical method.
17. The method of claim 1 wherein removing comprises breaking an interface between the growth substrate and the III-nitride layer with a blade.
18. The method of claim 1 wherein removing comprises one of mechanical grinding, applying a rotational force between the growth substrate and the III-nitride layer, attaching a first adhesive-coated plastic film to the growth substrate and a second adhesive-coated plastic film to a semiconductor structure including the III-nitride layer and pulling the growth substrate and III-nitride layer apart, using one of a pulse of sonic energy and an inhomogeneous temperature distribution to break an interface between the growth substrate and the III-nitride layer, and applying a temperature gradient across a surface normal of the III-nitride layer and growth substrate such that thermally induced stress in a plane of the III-nitride layer/growth substrate interface is sufficient to cause fracture of that interface.