Method for producing a buried semiconductor layer

A method for producing a power transistor in a semiconductor body, the power transistor including an n-doped substrate, an n-doped semiconductor layer provided on the n- doped substrate, and a p-doped region provided within the upper region of the n-doped semiconductor layer, the method comprising:

• a) irradiating at least a part of a front side of the semiconductor body with protons, and
• b) heat treating the semiconductor body at a temperature of approximately between 450 C and 550 C, wherein by the heat treatment a region of increased n-doping is formed in the n-doped semiconductor layer between the n-doped substrate and the p-doped region, which contains proton-induced donors and which includes an essentially homogenous doping profile due to a combination of the irradiated protons with defects caused by irradiation, wherein the homogenous doping profile extends from a doping maximum and in the direction of the front side of the semiconductor body, wherein the region of increased n-doping in the upper region of the n-doped semiconductor layer is immediately adjacent to the p-doped body region.