Composite structure and associated production method

A method of manufacturing a composite structure, the method including:

• forming a heterostructure comprising a useful layer and a support substrate adjacent to a first face of the useful layer at a first bonding interface, the useful layer comprising a piezoelectric material, the support substrate having a lower coefficient of thermal expansion than that of the useful layer, the first bonding interface having an adhesion energy of greater than or equal to 1500 mJ/m2;
• assembling a functional layer to the heterostructure to form the composite structure, an entire surface of the functional layer adjacent to a second face of the useful layer at a second bonding interface, the functional layer having a lower coefficient of thermal expansion than that of the useful layer;
• and
• heat treating the composite structure at a temperature higher than a limit temperature above which the heterostructure deteriorates or breaks in an absence of the functional layer.

A method of manufacturing a composite structure for an acoustic wave device, the method including:

• forming a composite structure comprising a useful layer including a first face and a second face opposite to the first face, a support substrate adjacent to the first face of the useful layer at a first bonding interface, and a functional layer adjacent to the second face of the useful layer at the second bonding interface,
• the useful layer comprising a piezoelectric material and having a higher coefficient of thermal expansion than that of the support substrate and that of the functional layer;
• heat treating the composite structure at a temperature higher than a limit temperature above which a heterostructure comprising the useful layer and the support substrate deteriorates or breaks in an absence of the functional layer;
• forming one or more local openings in at least one of the support substrate and the functional layer to enable access to at least one of the first face and the second face of the useful layer;
• and
• forming one or more components of the acoustic wave device on the at least one of the first face and the second face of the useful layer.