Process for fabricating a structure for epitaxy without an exclusion zone

1. A process for fabricating a composite structure for epitaxy, which comprises at least one crystalline growth seed layer of a semiconductor material on a support substrate, with the support substrate and crystalline growth seed layer(s) both having, on a periphery of their bonding face, a chamfer or an edge rounding zone, at least one step of bonding by molecular adhesion the crystalline growth seed layer onto the support substrate; and at least one step of thinning the crystalline growth seed layer, such that the crystalline growth seed layer has, after thinning, a diameter identical to its initial diameter.

2. The process as claimed in claim 1 , wherein, during the thinning step, the thickness of the crystalline growth seed layer removed is chosen so that the final thickness of the crystalline growth seed layer is greater than that over which the chamfer or the edge rounding zone extends.

3. The process as claimed in claim 2 , wherein the crystalline growth seed layer is thinned down to a final thickness of between 5 and 100 μm.

4. The process as claimed in claim 1 , wherein the crystalline growth seed layer has a defect density of less than 10 9 /cm 2 on its surface.

5. The process as claimed in claim 1 , wherein the support substrate is a material of: polycrystalline AN, single-crystal or polycrystalline GaN, single-crystal or polycrystalline SiC, sapphire, a ceramic, or a metal alloy.

6. The process as claimed in claim 5 , wherein the crystalline growth seed layer of semiconductor material is a material of: single-crystal Si, single-crystal SiC, single-crystal sapphire, or binary, ternary or quaternary Group III/V or Group III/N material.

7. The process as claimed in claim 1 , which further comprises, before the bonding step, a step of forming a bonding layer on the bonding face of the support substrate or on the bonding face of the crystalline growth seed layer of semiconductor material.

8. The process as claimed in claim 7 , wherein the bonding layer is an oxide, diamond, AlN or a silicon nitride layer.

9. The process as claimed in claim 1 , which further comprises planarizing the surface of each face to be bonded so as to obtain an surface roughness of less than 5 Å RMS.

10. A process for producing a layer of semiconductor material which comprises preparing a composite structure that includes a crystalline growth seed layer in accordance with the process as claimed in claim 1 ; and epitaxial growing a layer of semiconductor material on the composite structure.

11. The process as claimed in claim 10 , which further comprises forming a nucleation layer on the crystalline growth seed layer before epitaxially growing the layer of semiconductor material.

12. The process as claimed in claim 10 , wherein the epitaxial growth is carried out for a specified time so as to obtain a combined thickness of the layer of semiconductor material and of the crystalline growth seed layer of at least 100 μm.

13. The process as claimed in claim 12 , which further comprises a step of removing the support substrate and the crystalline growth seed layer.

14. The process as claimed in claim 10 , wherein the layer of semiconductor material is a GaN layer or a binary, ternary or quaternary Group III/N material.

15. The method of claim 1 which further comprises lapping the layer of semiconductor material after removing the support substrate and crystalline growth seed layer so as to obtain a bow of less than 50 microns.

16. A process for producing a layer of semiconductor material which comprises preparing a composite structure that includes a crystalline growth seed layer in accordance with a process for fabricating a composite structure for epitaxy, which comprises at least one crystalline growth seed layer of a semiconductor material on a support substrate, with the support substrate and crystalline growth seed layer(s) both having, on a periphery of their bonding face, a chamfer or an edge rounding zone, at least one step of bonding by molecular adhesion the crystalline growth seed layer onto the support substrate; and at least one step of thinning the crystalline growth seed layer, such that the crystalline growth seed layer has, after thinning, a diameter identical to its initial diameter; and epitaxial growing a layer of semiconductor material on the composite structure, wherein the epitaxial growth is carried out for a specified time so as to obtain a combined thickness of the layer of semiconductor material and of the crystalline growth seed layer of at least 100 μm, and wherein the process further comprises:

a step of removing the support substrate and the crystalline growth seed layer,

a double-sided lapping step carried out on the layer of semiconductor material after removing the support substrate and crystalline growth seed layer so as to obtain a bow of less than 50 microns,

a step of polishing the face exposed after the removal, and

a step of removing a peripheral portion of the layer of semiconductor material.