Process for transferring a thin layer to a support substrate that have different thermal expansion coefficients
A process for transferring a thin layer consisting of a first material to a support substrate consisting of a second material having a different thermal expansion coefficient, comprises providing a donor substrate composed of an assembly of a thick layer formed of the first material and of a handle substrate having a thermal expansion coefficient similar to that of the support substrate, and the donor substrate having a main face on the side of the thick layer introducing light species into the thick layer to generate a plane of weakness therein and to define the thin layer between the plane of weakness and the main face of the donor substrate; assembling the main face of the donor substrate with a face of the support substrate; and detachment of the thin layer at the plane of weakness, the detachment comprising application of a heat treatment.
1. A process for transferring a thin layer comprising a first material onto a support substrate comprising a second material, the first and the second materials having different coefficients of thermal expansion, the process comprising:
bonding a source substrate to a handle substrate by molecular adhesion, the source substrate comprising the first material, at least a portion of the bonded source substrate and the handle substrate forming a donor substrate comprising an assembly of a thick layer of the first material and a handle substrate, a coefficient of thermal expansion of the handle substrate being similar to that of the support substrate, and the donor substrate having a main face on the thick layer;
introducing light species into the thick layer to generate an embrittlement plane therein and to define the thin layer between the embrittlement plane and the main face of the donor substrate;
assembling the main face of the donor substrate with one face of the support substrate; and
detaching the thin layer from the embrittlement plane, the detachment comprising application of a heat treatment while the thick layer is assembled to and positioned between the handle substrate and the support substrates that have similar coefficients of thermal expansion that are different than the coefficient of thermal expansion of the first material, wherein the coefficient of thermal expansion of the first material of the thick layer and the coefficient of thermal expansion of the second material of the support substrate differ by at least 10% at room temperature.
2. The process of claim 1 , wherein a difference in coefficient of thermal expansion of the handle substrate and that the coefficient of thermal expansion of the support substrate is less, as an absolute value, than the difference in coefficient of thermal expansion of the thick layer and the coefficient of thermal expansion of the support substrate.
3. The process of claim 2 , wherein the introduced light species comprise hydrogen and/or helium ions.
4. The process of claim 3 , wherein the first material comprises a ferroelectric material.
5. The process of claim 4 , wherein the first material comprises a ferroelectric material selected from among LiTaO 3 , LiNbO 3 , LiAlO 3 , BaTiO 3 , PbZrTiO 3 , KNbO 3 , BaZrO 3 , CaTiO 3 , PbTiO 3 and KTaO 3 .
6. The process of claim 5 , wherein the support substrate comprises silicon.
7. The process of claim 6 , wherein the handling substrate is of the same composition as the support substrate.
8. The process of claim 1 , wherein the handle substrate has a thickness equal to a thickness of the support substrate.
9. The process of claim 1 , wherein the thick layer has a thickness of between 10 and 400 micrometers.
10. The process of claim 1 , further comprising thinning of the source substrate to provide the thick layer.
11. The process of claim 10 , wherein thinning the source substrate comprises at least one process selected from among milling the source substrate, chemical-mechanical polishing of the source substrate, and etching of the source substrate.
12. The process of claim 1 , wherein a difference in coefficient of thermal expansion of the handle substrate and that the coefficient of thermal expansion of the support substrate is less, as an absolute value, than the difference in coefficient of thermal expansion of the thick layer and the coefficient of thermal expansion of the support substrate.
13. The process of claim 1 , wherein the introduced light species comprise hydrogen and/or helium ions.
14. The process of claim 1 , wherein the first material comprises a ferroelectric material.
15. The process of claim 14 , wherein the first material comprises a ferroelectric material selected from among LiTaO 3 , LiNbO 3 , LiAlO 3 , BaTiO 3 , PbZrTiO 3 , KNbO 3 , BaZrO 3 , CaTiO 3 , PbTiO 3 and KTaO 3 .
16. The process of claim 1 , wherein the support substrate comprises silicon.
17. The process of claim 1 , wherein the handling substrate is of the same composition as the support substrate.