Patent ID: 7265536

Claim:
A procedure for exact reproduction of a calibration position of an aligned and afterwards displaced calibration substrate in a probe station having a wafer chuck mounted on a 4axis manipulator stage, a probe needle arrangement above the wafer chuck, and a first measurement system for detecting location of the wafer chuck relative to a machine frame, and a second measurement system for detecting location of the calibration substrate relative to the machine frame, comprising the steps of: a) loading a first wafer to the wafer chuck, b) loading a calibration substrate to the wafer chuck, c) aligning the first wafer relative to the probe needle arrangement so that a first home position aligned to the needle arrangement can be set and stored in a memory, d) aligning the calibration substrate to the probe needle arrangement, so that a calibration can be carried out, e) and storing this position as a calibration position in a memory, f) determining a first location of the calibration substrate relative to the machine frame in a defined offset distance related to the calibration position by means of the second measurement system, g) performing wafer measurements and calibrations, h) unloading the first wafer by disconnecting the wafer chuck from the 4axis manipulator stage, i) loading a second wafer by reconnecting the wafer chuck in a displaced position, and reproduction of the calibration position of the calibration substrate by j) determining a second location of the of the calibration substrate relative to the machine frame in the defined offset distance of step f) related to the calibration position by means of the second measurement system, k) calculating a difference between the first location and second location of the calibration substrate and correcting the defined offset distance by using that difference, getting a new offset distance, l) moving the wafer chuck to the calibration position from a recent position, using the new offset distance, which will lead to the reproduced calibration position and storing that position as a recent calibration position, and m) aligning the second wafer to the needle arrangement, so that a second home position is set and storing the second home position in a memory.