Patent ID: 7932160

Claim:
A process for the manufacture of a semiconductor comprising the steps of: (a) formation of a first semiconductor layer; (b) formation of a second semiconductor layer above the first semiconductor layer, according to a direction of formation Z, a concentration of species capable of being oxidised in the first layer being substantially weaker than a concentration of species capable of being oxidised in the second layer; (c) formation of a third semiconductor layer above the second semiconductor layer according to the direction of formation Z, a concentration of species capable of being oxidised in the third layer being substantially weaker than the concentration of species capable of being oxidised in the second layer; (d) formation of at least one diffusion zone on the third layer; (e1) diffusion of oxidising species in the material of the third layer according to a general direction of diffusion parallel to the direction of formation, (e2) oxidation of the second layer by diffusion of oxidising species through the third layer, wherein stage (d) is achieved by etching of the third layer at least at the level of the diffusion zone, over a predetermined depth in formation direction Z that is less than the thickness of the said third layer in the formation direction.