Patent ID: 7327155

Claim:
A method of testing a semiconductor wafer or sample having a substrate of semiconducting material, the method comprising: (a) providing first, second and third electrically conductive contacts positioned on a carrier in electrical isolation from each other; (b) providing an electrical power source connected to apply a first electrical bias to the first and second contacts and a second electrical bias to the third contact; (c) causing the contacts to move into spaced relation with a topside of a substrate of a semiconductor wafer or sample; (d) following step (c), causing the electrical power source to apply the first and second electrical biases such that an inversion layer forms in the substrate underlying at least the first contact; (e) measuring a value of a current that flows in the substrate in response to the applied voltage; (f) determining from the applied electrical biases and the measured current a surface mobility of minority carriers in the substrate; and (g) based on the surface mobility determined in step (f), determining whether the surface mobility of minority carriers in the substrate is acceptable.