Method of smoothing the outline of a useful layer of material transferred onto a support substrate

A method of providing a regular outline in a useful layer of material that is transferred from a source substrate onto a support substrate during the fabrication of a composite substrate for subsequent use in electronics, optics, or optoelectronics, which comprises:

• providing a shoulder on a front face of one of the source or support substrates about its periphery, wherein the shoulder defines an inner projecting zone that has a top face, a sidewall and a regular outline;
• molecularly bonding the top face of the projecting zone to a receiving face of the other of the source or support substrates, wherein the receiving face is bordered by a primary chamfer zone, a secondary chamfer zone, and a central zone having a flatness suitable for facilitating molecular bonding;
• and
• removing a portion of the source substrate to provide the useful layer having the regular outline on the support substrate.