Method of producing a heterostructure with local adaptation of the thermal expansion coefficient

1. A method of producing a heterostructure that comprises bonding a bonding surface of at least one first substrate having a first thermal expansion coefficient directly onto a bonding surface of a second substrate having a second thermal expansion coefficient, with the first thermal expansion coefficient being different from the second thermal expansion coefficient, the method further comprising, prior to bonding:

forming trenches in the bonding surfaces of both the first and second substrates;

filling the formed trenches with a filling material having a third thermal expansion coefficient that has a value that is between the first and second thermal expansion coefficients in order to reduce deformations or strains that would otherwise be observed during heat treatments of bonded substrates that do not include such filled trenches with the filling material also deposited over the bonding surfaces of the first and second substrates; and

planarizing the filling material to bonding to remove the filling material from the bonding surfaces but not from the trenches.

2. The method according to claim 1 , wherein the first substrate is made of a material having a thermal expansion coefficient of at least 5×10 −6 /° C., the second substrate is made of a material having a thermal expansion coefficient of 3.6×10 −6 /° C. or less and the material filling the trenches has a thermal expansion coefficient of less than 5×10 −6 /° C. and greater than 3.6×10 −6 /° C.

3. The method according to claim 1 , wherein the first substrate is formed from silicon, germanium, gallium arsenide or gallium nitride and the second substrate is formed from sapphire, a borosilicate glass, or silicon.

4. The method according to claim 1 , wherein the filling material is silicon-germanium, germanium, a silicon nitride, or a borophosphosilicate glass.

5. The method according to claim 1 , wherein the trenches of the first substrate are aligned with the trenches of the second substrate when the first and second substrates are bonded.

6. The method according to claim 1 , wherein microcomponents are present on at least one of the first and second substrates.

7. The method according to claim 6 , wherein the trenches are produced in predetermined zones such that the trenches are adjacent the microcomponents.

8. The method according to claim 1 , which further comprises oxidizing one or both of the bonding surfaces including the trenches prior to filling the trenches and bonding the first and second substrates.

9. The method according to claim 1 , which further comprises cleaning and activating one or both of the bonding surfaces prior to bonding the first and second substrates.

10. The method according to claim 1 , wherein the filling material in the trenches of the first substrate has a fourth thermal expansion coefficient that has a value that is between the first and second thermal expansion coefficients and is different from the filling material in the trenches of the second substrate.

11. A method of reducing deformations or strains in bonded substrates during heat treatments, which comprises:

prior to bonding, forming trenches in a bonding surface of each of first and second substrates that are to be bonded together, wherein the first substrate has a first thermal expansion coefficient and the second substrate has a second thermal expansion coefficient, with the first thermal expansion coefficient being different from the second thermal expansion coefficient;

filling the formed trenches with a filling material having a third thermal expansion coefficient that has a value that is between the first and second thermal expansion coefficients with the filling material also deposited over the bonding surfaces of the first and second substrates;

bonding the surface of the first substrate onto the bonding surface of the second substrate in order to reduce deformations or strains that would otherwise be observed during heat treatments of bonded substrates that do not include such filled trenches; and

planarizing the filling material prior to bonding to remove the filling material from the bonding surfaces but not from the trenches.

12. The method according to claim 11 , wherein the filling material in the trenches of the first substrate has a fourth thermal expansion coefficient that has a value that is between the first and second thermal expansion coefficients and is different from the filling material in the trenches of the second substrate.

13. A heterostructure comprising at least one first substrate having a first thermal expansion coefficient bonded to a second substrate having a second thermal expansion coefficient, with the first thermal expansion coefficient being different from the second thermal expansion coefficient, wherein each of the first and second substrates includes a bonding surface with trenches therein and the trenches contain a filling material having a third thermal expansion coefficient that has a value that is between the first and second thermal expansion coefficients.

14. The heterostructure according to claim 13 , wherein the first substrate is formed of silicon, germanium, gallium arsenide or gallium nitride and the second substrate is formed of sapphire, a borosilicate glass, or silicon.

15. The heterostructure according to claim 13 , wherein the trenches of the first substrate are aligned with the trenches of the second substrate.

16. The heterostructure according to claim 13 , wherein one of the first and second substrates includes microcomponents.

17. The heterostructure according to claim 16 , wherein the microcomponents are disposed in zones between the trenches.

18. The hetero structure according to claim 13 , wherein the filling material in the trenches of the first substrate has a fourth thermal expansion coefficient that has a value that is between the first and second thermal expansion coefficients and is different from the filling material in the trenches of the second substrate.