Method of fabricating a release substrate
View Patent ↗The invention relates to a method of fabricating a release substrate produced from semiconductor materials, the method comprising creating a reversible connection between two substrate release layers characterized in that the reversible connection is formed by a connecting layer produced using a first material as the basis, the connecting layer further comprising a nanoparticle concentrating zone of a second material disposed to facilitate release of the substrate, the first and second materials being selected to maintain the bonding energy of the reversible connection substantially constant even when the substrate is exposed to heat treatment.
1. A method of fabricating a release substrate of semiconductor materials, which comprises forming a reversible connection between two substrate release layers by providing a connecting layer of a first material, and providing a concentrated zone of nanoparticles of a second material in the connecting layer as a first substrate release layer to facilitate release of the substrate release layers, with the connecting layer having a bonding energy that is substantially constant even when the release substrate is exposed to heat treatment, wherein the connecting layer is formed by:
providing a first elemental layer of the first material adjacent the first substrate release layer;
forming an enriched layer by providing a second elemental layer of the second material or a precursor for the second material on the surface of the first elemental layer;
further providing a third elemental layer of the first material on the surface of the enriched layer; and
heat treating the enriched layer to cause segregation of nanoparticles of the second material thus forming a second release layer.
2. The method of claim 1 , wherein the enriched layer is produced by deposition onto the first elemental layer.
3. The method of claim 1 , wherein the first elemental layer is produced by deposition onto a first substrate release layer.
4. The method of claim 3 , wherein the first elemental layer is produced by thermal oxidation of a portion of the first substrate release layer.
5. The method of claim 1 , wherein the third elemental layer of first material is produced by deposition onto the enriched layer.
6. The method of claim 1 , wherein the enriched layer has a thickness sufficient to produce the third elemental layer of first material by thermal oxidation of a portion of the thickness of the enriched layer.
7. The method of claim 1 , wherein the third elemental layer of the first material is provided by:
forming a further elemental layer of the first material on the second release layer; and
bonding the further elemental layer on the second substrate release layer to the surface of the enriched layer.
8. The method of claim 7 , wherein the further elemental layer of first material is produced by thermal oxidation of a portion of the second substrate release layer prior to joining the second release layer to the surface of the enriched layer.
9. The method of claim 1 , wherein the concentrated zone of nanoparticles of the second material is provided by carrying out a segregation heat treatment of the connecting layer at a temperature on the order of 900° C. to 1100° C. for a sufficient time to form the nanoparticles and the bonding energy of the connecting layer does not weaken when the substrate is exposed to heat treatment.
10. The method of claim 9 wherein the segregation heat treatment is conducted for about 25 to 95 minutes, optionally in an inert atmosphere of nitrogen, argon or mixtures thereof.
11. The method of claim 1 , wherein the second release layer is formed on the connecting layer after creating an enriched region in the connecting layer.
12. The method of claim 1 , wherein at least one release layer is provided by a layer transfer technique.
13. The method of claim 12 , wherein the layer transfer technique comprises implantation of ions in a source substrate to form a weakened zone followed by bonding of the source substrate to the connecting layer, then followed by detachment of the that release layer from the source substrate at the weakened zone.
14. The method of claim 13 , wherein at least one other release layer is provided by a layer transfer technique.
15. The method of claim 14 , wherein the layer transfer technique for the other release layer comprises implantation of ions in a source substrate to form a weakened zone followed by bonding of the source substrate to the connecting layer, then followed by detachment of the previous release layer from the source substrate at the weakened zone.
16. The method of claim 1 , wherein the first material is SiO 2 .
17. The method of claim 1 , wherein the second material is Si.
18. The method of claim 1 , wherein the enrichment material is SiO.
19. The method of claim 1 , wherein the second material is Ge.
20. The method of claim 1 , wherein the enriched region is produced by implanting the enrichment material into the initial layer.