Semiconductor structure comprising a buried porous layer for RF applications

A method of fabricating a semiconductor structure for radiofrequency applications, the method comprising:

• a step a) of providing a donor substrate including a buried weakened plane delimiting a surface layer with respect to a front face of the donor substrate;
• a step b) of providing a carrier substrate comprising silicon, the carrier substrate exhibiting a resistivity of between 0.5 ohm·cm and 4 ohm·cm;
• a step c) of porosifying the carrier substrate and forming a mesoporous layer in a front portion of the carrier substrate, the mesoporous layer exhibiting a resistivity higher than 20 kohm·cm, the mesoporous layer having a thickness between 3 μm and 40 μm;
• a step d) of annealing the carrier substrate under an oxidizing atmosphere at a temperature of between 300° C. and 400° C. to stabilize the mesoporous layer with hollow pores, internal walls of the hollow pores being coated with oxide, the hollow pores not being completely filled with a solid material;
• a step e) of depositing a dielectric layer on the mesoporous layer,
• a step f) of attaching the donor substrate, via the front face thereof, to the dielectric layer;
• and
• a step g) of separating the donor substrate along the buried weakened plane order to transfer the surface layer to the carrier substrate.