Method for manufacturing a composite structure comprising a thin layer made of monocrystalline sic on a carrier substrate made of SiC
A method for manufacturing a composite structure comprising a thin layer made of monocrystalline silicon carbide arranged on a carrier substrate made of silicon carbide, the method comprising: a) a step of providing a donor substrate made of monocrystalline silicon carbide, b) a step of ion implantation of light species into the donor substrate, to form a buried brittle plane delimiting the thin layer between the buried brittle plane and a free surface of the donor substrate, c) a succession of n steps of forming crystalline carrier layers, with n greater than or equal to 2; the n crystalline carrier layers being positioned on the front face of the donor substrate successively one on the other, and forming the carrier substrate; each formation step comprising: direct liquid injection chemical vapor deposition, at a temperature below 900° C., to form a carrier layer, the carrier layer being formed by an at least partially amorphous SiC matrix, and having a thickness of less than or equal to 200 microns; a crystallization heat treatment of the carrier layer, at a temperature of less than or equal to 1000° C., to form a crystalline carrier layer; d) a step of separation along the buried brittle plane, to form, on the one hand, a composite structure comprising the thin layer on the carrier substrate and, on the other hand, the rest of the donor substrate.
1. A process for manufacturing a composite structure comprising a thin layer made of monocrystalline silicon carbide arranged on a carrier substrate made of silicon carbide, the process comprising:
a) a step of providing a donor substrate made of monocrystalline silicon carbide;
b) a step of ion implantation of light species into the donor substrate to form a buried brittle plane delimiting the thin layer between the buried brittle plane and a free surface of the donor substrate;
c) a succession of n steps of forming crystalline carrier layers, with n greater than or equal to 2, the n crystalline carrier layers being positioned on a front face of the donor substrate successively one on the other and forming the carrier substrate, each formation step comprising:
direct liquid injection chemical vapor deposition, at a temperature below 900° C., to form a carrier layer, the carrier layer being formed by an at least partially amorphous SiC matrix, and having a thickness of less than or equal to 200 microns; and
a crystallization heat treatment of the carrier layer, at a temperature of less than or equal to 1000° C., to form a crystalline carrier layer; and
d) a step of separation along the buried brittle plane to form, on the one hand, a composite structure comprising the thin layer on the carrier substrate and, on the other hand, a remainder of the donor substrate.
2. The process of claim 1 , further comprising:
e) a step of mechanical and/or chemical treatment of the composite structure, the mechanical and/or chemical treatment being applied to a free rear face of the composite structure, and/or to a free face of the thin layer.
3. The process of claim 2 , wherein step e) comprises simultaneous chemical-mechanical polishing of the front face and of the rear face of the composite structure.
4. The process of claim 1 , wherein chemical etching, mechanical grinding and/or chemical-mechanical polishing is applied to a free face of the carrier substrate between step c) and step d).
5. The process of claim 1 , wherein the thickness of each deposited carrier layer is less than or equal to 100 microns.
6. The process of claim 1 , wherein the chemical vapor depositions in step c) are performed at a temperature of between 100° C. and 800° C.
7. The process of claim 1 , wherein the chemical vapor depositions in step c) are performed at a pressure of between 1 Torr and 500 Torr.
8. The process of claim 1 , wherein precursors used during the chemical vapor depositions in step c) are chosen from polysilylethylene and disilabutane.
9. The process of claim 1 , wherein step c) comprises a succession of n steps of forming crystalline carrier layers, with n between 3 and a few dozen.
10. The process of claim 1 , wherein step a) comprises:
a′) a step of providing an initial substrate made of monocrystalline silicon carbide; and
a″) a step of epitaxial growth of a monocrystalline silicon carbide donor layer on the initial substrate to form the donor substrate, the monocrystalline silicon carbide donor layer having a density of crystal defects less than that of the initial substrate.
11. The process of claim 10 , wherein step a′) comprises formation, on the initial substrate, of a monocrystalline conversion layer to convert basal plane dislocation defects of the initial substrate into threading edge dislocation defects.
12. The process of claim 10 , wherein the epitaxial growth step a″) is performed at a temperature above 1200° C.
13. The process of claim 1 , wherein the separation step d) is performed at a temperature greater than or equal to the temperature of the crystallization heat treatments of step c).
14. The process of claim 1 , further comprising a step of reconditioning the remainder of the donor substrate to reuse the donor substrate as another initial substrate or as another donor substrate.
15. The process of claim 5 , wherein the thickness of each deposited carrier layer is less than or equal 50 microns.
16. The process of claim 15 , wherein the thickness of each deposited carrier layer is less than or equal 10 microns.
17. The process of claim 6 , wherein the chemical vapor depositions in step c) are performed at a temperature of between 200°° C. and 600° C.
18. The process of claim 12 , wherein the epitaxial growth step a″) is performed at a temperature between 1500° C. and 1650° C.