Method for manufacturing a composite structure comprising a thin film of monocrystalline SIC on a carrier substrate of polycrystalline SIC

A method of fabricating a composite structure including a thin layer of single-crystal silicon carbide on a carrier substrate of polycrystalline silicon carbide, the method comprising:

• providing an initial substrate of single-crystal silicon carbide;
• depositing a first layer of polycrystalline silicon carbide over a front side of the initial substrate at a temperature above 1100° C., the first layer having a thickness less than 1 μm and a dopant concentration greater than 1019/cm3;
• implanting light ionic species through the first layer to form a buried brittle plane in the initial substrate, the thin layer being delineated between the buried brittle plane and the front side of the initial substrate;
• depositing a second layer of amorphous and/or polycrystalline silicon carbide on the first layer at a temperature below 900° C., the second layer having a thickness greater than or equal to 10 μm and a concentration of dopants, of the same type as a type of dopants of the first layer, the concentration of dopants in the second layer being greater than 1019/cm3;
• depositing a third layer of polycrystalline silicon carbide on the second layer at a temperature above 1000° C., a separation along the buried brittle plane occurring during the deposition of the third layer, the first layer, second layer and third layer forming the carrier substrate of the composite substrate.