Robot calibration system and method

1. A calibration system for use with a wafer processing system having a station and a robot with an end effector sized and dimensioned to handle a semiconductor wafer comprising:

a calibration array sized and dimension for holding by the end effector, said calibration array comprising a plurality of proximity sensors and an optical sensor;

a dummy wafer sized and dimensioned for placement in the station, said dummy wafer having an aperture disposed in approximately its center; and

a control system in electrical communication with the calibration array and the robot wherein the control system is programmed to determine the distance of the station relative to the robot using the proximity sensors and programmed to determine the approximate center of the station with the optical sensor when the calibration array is placed in proximity to the dummy wafer.

2. The calibration system of claim 1 wherein the dummy wafer is a disk.

3. The calibration system of claim 1 wherein the calibration array is characterized by a coordinate system with an origin, an x-axis and z-axis and the optical sensor is disposed at the approximate origin.

4. The calibration system of claim 3 wherein the plurality of proximity sensors comprises a first sensor disposed within x+ quadrants, a second sensor is disposed within x− quadrants, a third sensor is disposed within z+ quadrants and a fourth sensor is disposed within z− quadrants.

5. The calibration system of claim 1 wherein plurality of proximity sensors comprise inductive sensors.

6. The calibration system of claim 1 further comprising a calibration stand with an opening sized and dimensioned to receive the calibration array.

7. The calibration system of claim 1 wherein the calibration array further comprises a substantially planar sensor mount.

8. The calibration system of claim 1 wherein the control computer is further programmed to align an end effector coordinate system with a transformation in a robot control system using at least three translational values and at least three rotational values.

9. A method for calibrating a robot for use with a wafer processing system having a station, said a robot having an end effector sized and dimensioned to handle semiconductor wafers, said method comprising:

providing a calibration array sized and dimension for holding by the end effector, said calibration array comprising a plurality of proximity sensors and an optical sensor;

providing a dummy wafer sized and dimensioned to for placement in the station, said dummy wafer having a void disposed in approximately its center;

disposing the calibration array in the end effector;

disposing the dummy wafer in the station;

determining the planarity of the dummy wafer relative to the calibration array.

10. The method of claim 9 further comprising the step of calibrating the proximity sensors with a calibration stand.

11. The method of claim 9 further comprising the step of moving the calibration array within about 0.002″ of the dummy wafer.

12. A method for calibrating a robot for use with a wafer processing system having a station, said a robot having an end effector sized and dimensioned to handle semiconductor wafers, said method comprising:

providing a calibration array sized and dimension for holding by the end effector, said calibration array comprising a z+ proximity sensor, z− proximity senor, x+ proximity sensor, an x− proximity sensor and an optical sensor;

providing a dummy wafer sized and dimensioned to for placement in the station, said dummy wafer having a void disposed in approximately its center;

disposing the calibration array in the end effector;

disposing the dummy wafer in the station;

moving the end effector with the calibration array towards the dummy wafer in the y-direction;

recording the location at which the z+ sensor trips;

moving the end effector in the z− direction a distance of Δz;

moving the end effector in the y-direction until the z+ sensor trips a second time;

recording the location at which the z+ sensor trips the second time.

13. The method of claim 12 further comprising the steps of:

moving the end effector with the calibration array towards the dummy wafer in the y-direction;

recording the location at which the x+ sensor trips;

moving the end effector in the x− direction a distance of Δx;

moving the end effector in the y-direction until the x+ sensor trips a second time;

recording the location at which the x+ sensor trips the second time.