Epitaxial Lift-Off and Wafer Reuse
A method of reusing a III-nitride growth substrate according to embodiments of the invention includes epitaxially growing a III-nitride semiconductor structure on a III-nitride substrate. The III-nitride semiconductor structure includes a sacrificial layer and an additional layer grown over the sacrificial layer. The sacrificial layer is implanted with at least one implant species. The III-nitride substrate is separated from the additional layer at the implanted sacrificial layer. In some embodiments the III-nitride substrate is GaN and the sacrificial layer is GaN, an aluminum-containing III-nitride layer, or an indium-containing III-nitride layer. In some embodiments, the III-nitride substrate is separated from the additional layer by etching the implanted sacrificial layer.
1 . A method comprising:
epitaxially growing a III-nitride semiconductor structure on a III-nitride substrate, the III-nitride semiconductor structure comprising:
a sacrificial layer; and
an additional layer grown over the sacrificial layer;
implanting the sacrificial layer with at least one implant species;
thereafter, growing one or more semiconductor layers over the additional layer; and
separating the III-nitride substrate from the additional layer at the implanted sacrificial layer.
2 . The method of claim 1 further comprising after separating the III-nitride substrate from the additional layer, polishing the III-nitride substrate and growing a III-nitride layer on the III-nitride substrate.
3 . The method of claim 1 wherein the III-nitride substrate is GaN.
4 . The method of claim 1 wherein the additional layer is the same material as the III-nitride substrate.
5 . The method of claim 1 wherein the sacrificial layer comprises aluminum.
6 . The method of claim 1 wherein the sacrificial layer comprises at least one of GaN, AlN, AlGaN, or an indium-containing III-nitride layer.
7 . The method of claim 1 wherein the substrate is GaN, the sacrificial layer is AlN, and the additional layer is GaN.
8 . The method of claim 1 wherein the substrate is GaN, the sacrificial layer is GaN, and the additional layer is GaN.
9 . The method of claim 1 wherein the sacrificial layer is a compositional super-lattice comprising alternating first and second layers, the first layers having a different composition than the second layers.
10 . The method of claim 9 wherein the first layers comprise aluminum and the second layers are GaN.
11 . The method of claim 9 wherein the first layers comprise indium and the second layers are GaN.
12 . The method of claim 9 wherein the compositional super-lattice comprises at least two pairs of alternating first and second layers.
13 . The method of claim 1 wherein the implant species comprises at least one of He or H.
14 . The method of claim 1 wherein the sacrificial layer is implanted with at least two implant species, wherein one of the implant species is O.
15 . The method of claim 1 wherein separating comprises etching.
16 . The method of claim 14 wherein etching comprises etching with HF.
17 . The method of claim 1 wherein separating comprises mechanically separating.
18 . The method of claim 1 wherein epitaxially growing a III-nitride semiconductor structure on a III-nitride substrate further comprises epitaxially growing a spacer layer disposed between the III-nitride substrate and the sacrificial layer.
19 . The method of claim 18 wherein the spacer layer is GaN.
20 . The method of claim 1 wherein the additional layer is a first additional layer, the method further comprising after implanting the sacrificial layer and before separating the III-nitride substrate from the additional layer, growing a second additional III-nitride layer on the first additional layer.
21 . The method of claim 1 wherein implanting the sacrificial layer makes the sacrificial layer at least partially amorphous.
22 . The method of claim 1 wherein implanting the sacrificial layer creates at least one void in the sacrificial layer.