Method for manufacturing a composite structure comprising a thin single-crystal semiconductor layer on a carrier substrate

A method of fabricating a composite structure comprising a thin layer of a single-crystal semiconductor, the thin layer being disposed on a carrier substrate, the method comprising:

• a) providing a donor substrate composed of the single-crystal semiconductor;
• b) implanting ions of a light species into the donor substrate, with the exception of an annular peripheral region of the donor substrate, under implantation conditions, to form a buried weak plane delimiting the thin layer between the buried weak plane and a front side of the donor substrate;
• the buried weak plane comprising lenticular microcavities apt to develop, when activated thermally, into microcracks;
• the implantation conditions defining a first thermal budget for obtaining blistering on the front side of the donor substrate, and a second thermal budget for obtaining splitting in the buried weak plane;
• and
• the blistering corresponding to deformation of the thin layer plumb with the microcracks, and the splitting corresponding to complete splitting in the buried weak plane;
• c) forming a stiffening film on the donor substrate, carried out with application of a thermal budget lower than the first thermal budget, the stiffening film:
• being apertured and taking, in the plane of the front side, the form of a grid with a degree of coverage between 5% and 30%, and leaving a plurality of regions of the front side bare, these regions taking the form of features the lateral dimensions of which are smaller than or equal to 50 microns;
• and
• having a thickness larger than or equal to 0.5 microns;
• d) depositing a carrier substrate on the front side of the donor substrate, the front side having the stiffening film thereon, the depositing of the carrier substrate being carried out with application of a thermal budget higher than the first thermal budget;
• and
• e) cleaving to form the composite structure and a remainder of the donor substrate.