Semiconductor component comprising a buried mirror

1. A method for forming a buried mirror in a semiconductor component, comprising:

forming a structure comprising a semiconductor layer laid on an insulating layer covering a substrate;

forming one or several openings in the semiconductor layer emerging at the surface of the insulating layer;

eliminating a portion of the insulating layer, whereby a recess is formed;

forming a second thin insulating layer against the wall of the recess; and

forming a metal layer in the recess against the second insulating layer.

2. The method of claim 1 , wherein the second thin insulating layer has a thickness smaller than one quarter of the wavelength of the light likely to be reflected by the mirror.

3. The method of claim 1 , comprising, prior to the forming of the openings, the steps of:

etching the semiconductor layer, the insulating layer, and the upper portion of the substrate to form a trench surrounding said portion of the insulating layer; and

filling the previously-formed trench with a material different from said portion.

4. The method of claim 1 , wherein the substrate and the semiconductor layer are formed of single-crystal silicon, the insulating layer being formed of silicon oxide.

5. The method of claim 1 , wherein the metal layer is aluminum.