Patent ID: 8038895

Claim:
A method for the production of a multiplicity of semiconductor wafers, comprising a) producing a semiconductor ingot; b) cutting of the semiconductor ingot into ingot sections having at least one planar surface and a thickness, measured at right angles to the planar surface, of 1 cm to 100 cm: d) determining the position of mechanical defects in each ingot section, comprising scanning the planar surface of the ingot section by at least one ultrasound transducer which is coupled via a liquid coupling medium to the planar surface of the ingot section and, at each measurement point (x,y) produces at least one ultrasound pulse which is directed at the planar surface of the ingot section, and recording the ultrasound-pulse echo originating from the ingot section as a function of time, such that an echo from the planar surface, an echo from a surface, opposite the planar surface of the ingot section and further echoes are detected when mechanical defects are present, and determining the positions (x p , y p , z p ) of mechanical defects, in the ingot section from the further echoes, or by illuminating the ingot section from one end with infrared light, measuring the intensity of infrared light at an opposite end of the ingot section, and determining the positions (x p , y p , z p ) of mechanical defects, with the position of each mechanical defect being defined uniquely by coordinates x p , y p on a plane parallel to the cuts to be made in step f), as well as by a coordinate z p at right angles to this plane; f) cutting the ingot sections into a multiplicity of semiconductor wafers with a thickness of 0.2 to 2 mm; and h) segregating those semiconductor wafers which contain the positions at which mechanical defects have been found.