Carrier substrate for SOI structure and associated production process

The invention relates to a carrier substrate (10) made of monocrystalline silicon, having a front face (10a) and a back face (10b) and comprising: - a surface region (1) from the front face (10a) down to a depth of between 800 nm and 2 microns, having fewer than 10 crystal-originated particles (COPs) detected by inspecting the surface using dark-field microscopy, - an upper region (2) extending from the front face (10a) down to a depth of between a few microns and 40 microns, having an interstitial oxygen (Oi) content lower than or equal to 7.5E17 Oi/cm3 and a resistivity higher than 500 ohm.cm, and - a lower region (3) extending between the upper region (2) and the back face (10b), having a micro-defect (BMD) concentration higher than or equal to 1E8/cm3. The invention also relates to a process for manufacturing such a carrier substrate (10).