Structure for device with integrated microelectromechanical systems
A method for manufacturing a structure comprises a) providing a donor substrate comprising front and rear faces; b) providing a support substrate; c) forming an intermediate layer on the front face of the donor substrate or on the support substrate; d) assembling the donor and support substrates with the intermediate layer therebetween; e) thinning the rear face of the donor substrate to form a useful layer of a useful thickness having a first face disposed on the intermediate layer and a second free face; and wherein the donor substrate comprises a buried stop layer and a fine active layer having a first thickness less than the useful thickness, between the front face of the donor substrate and the stop layer; and after step e), removing, in first regions of the structure, a thick active layer delimited by the second free face of the useful layer and the stop layer.
1. A method for manufacturing a structure, comprising:
a) providing a donor substrate comprising a front face and a rear face and comprising a buried stop layer and a fine active layer having a first thickness less than a useful thickness, the fine active layer disposed between the front face of the donor substrate and the stop layer;
b) providing a support substrate;
c) forming an intermediate layer on the front face of the donor substrate or on the support substrate;
d) assembling the donor substrate and the support substrate so as to dispose the intermediate layer between the donor substrate and the support substrate;
e) thinning the rear face of the donor substrate so as to form a useful layer of the useful thickness having a first face disposed on the intermediate layer and a second free face; and
f) after step e), removing in first regions of the structure, a thick active layer delimited by the second free face of the useful layer and the stop layer, the buried stop layer being continuous over the entire extent of the structure when said removal in first regions is performed;
the method further comprising:
etching the stop layer so that the useful layer comprises only the fine active layer in the first regions;
etching the first thickness of the fine active layer in first patterns in the first regions;
etching the useful thickness of the useful layer in second patterns in second regions; and
removing the intermediate layer in at least part of the first regions and second regions of the structure so as to release at least one membrane of the fine active layer and at least one membrane of the useful layer.
2. The method of claim 1 , wherein the fine active layer is continuous over the entire extent of the donor substrate.
3. The method of claim 1 , wherein the fine active layer is non-continuous over the entire extent of the donor substrate.
4. The method of claim 1 , wherein the useful thickness is greater than 3 microns.
5. The method of claim 1 , wherein the first thickness is less than 20% of the useful thickness.
6. The method of claim 1 , wherein the first thickness is less than 1 micron.
7. The method of claim 1 , wherein the stop layer is formed by ion implantation.
8. The method of claim 7 , wherein ions implanted by the ion implantation are selected from the group consisting of hydrogen, helium, argon, boron, oxygen, nitrogen and carbon.
9. The method of claim 1 , further comprising forming the donor substrate, and wherein forming the donor substrate comprises:
forming a layer on the front face of an initial substrate, the layer having a chemical composition or crystalline structure different from that of the initial substrate, the layer forming the stop layer; and
forming the fine active layer of controlled thickness on the stop layer.
10. The method of claim 1 , wherein the fine active layer has a uniformity of thickness better than 5% over the entire extent of the structure.
11. The method of claim 1 , wherein the fine active layer and the thick active layer comprise the same material.
12. The method of claim 1 , wherein the fine active layer is formed from a material different from a material of the thick active layer.
13. The method of claim 1 , wherein the fine active layer comprises a material selected from the group consisting of silicon, silicon germanium, and germanium.
14. The method of claim 1 , wherein the thick active layer comprises a material selected from the group consisting of silicon, silicon germanium, and germanium.
15. The method of claim 1 , wherein the intermediate layer comprises a material selected from the group consisting of silicon oxide, silicon nitride, silicon oxynitride, a silicon germanium compound, porous silicon, silicon comprising microcavities and/or cracks filled with vacuum or gaseous species, and silicon containing nanoparticles.
16. The method of claim 1 , wherein the buried stop layer comprises a material selected from the group consisting of highly doped silicon, silicon germanium, germanium, silicon carbide, and a compound comprising a plurality of elements chosen from silicon, germanium, carbon and tin.
17. The method of claim 1 , wherein the buried stop layer has a third thickness of between 0.01 micron and 2 microns.
18. The method of claim 1 , wherein the support substrate comprises a material selected from the group consisting of silicon, glass, sapphire, silicon carbide, alumina, aluminum nitride and ceramics.
19. The method of claim 1 , wherein the support substrate comprises a layer of microelectronic or optoelectronic components or sensors.