Fabrication of substrates with a useful layer of monocrystalline semiconductor material
View Patent ↗The invention relates to methods for fabricating a semiconductor substrate. In one embodiment, the method includes providing a support that includes a barrier layer thereon for preventing loss by diffusion of elements derived from dissociation of the support at epitaxial growth temperatures; providing a seed layer on the barrier layer, wherein the seed layer facilitates epitaxial growth of a single crystal III-nitride semiconductor layer thereon; epitaxially growing a nitride working layer on the thin seed layer; and removing the support to form the semiconductor substrate.
1. A method for fabricating a semiconductor substrate, comprising:
transferring a nucleation layer from a source substrate to a support substrate by implanting ions within the source substrate and bonding the source substrate to the support substrate by molecular adhesion and subsequently detaching the nucleation layer from the source substrate to form an intermediate assembly, the intermediate assembly comprising the support substrate and the nucleation layer, the nucleation layer comprising a material selected from the group consisting of sapphire, silicon carbide, zinc oxide, gallium nitride, neodymium gallate, and lithium gallate;
epitaxially depositing at least one layer of a semiconductor material upon the nucleation layer of the intermediate assembly, wherein the support substrate comprises a material having a coefficient of thermal expansion about 0.7 to 3 times a coefficient of thermal expansion of the at least one layer of semiconductor material;
bonding a target substrate to the at least one layer of the semiconductor material to form a support assembly comprising the target substrate, the at least one layer of the semiconductor material, and the intermediate assembly; and
processing the support assembly so as to remove at least the support substrate, and providing a semiconductor substrate comprising the at least one layer of the semiconductor material on the target substrate.
2. The method of claim 1 , wherein at least one bonding layer is provided on the support substrate or on the nucleation layer or on both the support substrate and the nucleation layer.
3. The method of claim 1 , wherein the at least one layer of the semiconductor material has a dislocation concentration therein less than about 10 7 /cm 2 .
4. The method of claim 1 , wherein the support substrate and the at least one layer of the semiconductor material have equal coefficients of thermal expansion.
5. The method of claim 1 , wherein the nucleation layer comprises a barrier layer having a composition hindering diffusion of atoms from the support substrate to the at least one layer of the semiconductor material at epitaxial growth temperatures.
6. The method of claim 1 , further comprising providing a barrier layer between the nucleation layer and the support substrate, and epitaxially depositing the at least one layer of the semiconductor material on the nucleation layer after providing the barrier layer between the nucleation layer and the support substrate.
7. The method of claim 5 , wherein the barrier layer is deposited upon the support substrate.
8. The method of claim 2 , wherein the at least one bonding layer comprises a layer of adhesive applied to a surface of a barrier layer or a surface of the nucleation layer.
9. The method of claim 1 , further comprising forming the support substrate to comprise a barrier layer thereon having a composition resistant to diffusion of elements derived from dissociation of the intermediate assembly at epitaxial growth temperatures, and wherein the at least one layer of the semiconductor material is epitaxially deposited on the nucleation layer.
10. The method of claim 1 , wherein removing at least the support substrate comprises removing the support substrate by etching.
11. The method of claim 1 , further comprising selecting the semiconductor material of the at least one layer of the semiconductor material to comprise at least one metal nitride.
12. The method of claim 1 , wherein the support substrate comprises a material selected from the group consisting of silicon, silicon carbide, aluminum nitride, sapphire, gallium arsenide, zinc oxide, lithium gallium oxide and lithium aluminum oxide, wherein the semiconductor material of the at least one layer of the semiconductor material comprises a metal nitride, and wherein the target substrate comprises at least one of monocrystalline silicon and polycrystalline silicon.
13. The method of claim 1 , wherein the semiconductor material of the at least one layer of the semiconductor material comprises gallium nitride.
14. The method of claim 1 , further comprising:
forming at least one electroluminescent component in the at least one layer of the semiconductor material; and
applying a reflective coating on the target substrate, the reflective coating configured to reflect at least one of visible and ultraviolet radiation emitted by the at least one electroluminescent component.
15. The method of claim 1 , further comprising chemically treating the support assembly and removing at least one of the support substrate and the nucleation layer.
16. The method of claim 1 , wherein the chemical composition of the nucleation layer is the same as a chemical composition of the support substrate of the intermediate assembly.
17. The method of claim 1 , further comprising preparing the nucleation layer to receive the at least one layer of the semiconductor material, wherein the preparation includes at least one of polishing, annealing, smoothing, oxidation, and etching.
18. The method of claim 1 , further comprising recycling and reusing the support substrate after removing at least the support substrate.
19. The method of claim 14 , wherein the reflective coating comprises a metal layer, and further comprising forming the metal layer between the target substrate and the at least one layer of semiconductor material.
20. The method of claim 1 , wherein the source substrate comprises a material having a coefficient of thermal expansion different than a coefficient of thermal expansion of the at least one layer of semiconductor material.
21. The method of claim 1 , wherein the source substrate comprises a material having a coefficient of thermal expansion different than a coefficient of thermal expansion of a material of the support substrate.