A probe station for testing a wafer.
1. A probe station for probing an electrical device with at least one probe needle, said probe station comprising:
(a) a chuck having an upper surface capable of supporting an electrical device for probing by contact with the tip of said at least one probe needle;
(b) an auxiliary chuck mounted to said probe station and configured to receive a calibration substrate at a location suitable for probing by contact with the tip of said at least one probe needle so as to calibrate test instrumentation used to test an electrical device supported by said chuck; and wherein
(c) said chuck is capable of independent rotation relative to said auxiliary chuck.
2. The probe station of claim 1 where said auxiliary chuck has an upper surface substantially parallel with that of said chuck.
3. The probe station of claim 2 where the upper surfaces of said chuck and said auxiliary chuck, respectively, lie in substantially the same plane.
4. The probe station of claim 1 having a plurality of said auxiliary chucks.
5. The probe station of claim 4 where said plurality of auxiliary chucks are positioned around the periphery of said chuck.