Touch calibration system for wafer transfer robot

A method for automatically calibrating the positioning of the end-effector of a wafer handling robot to a precise location within an enclosure forming a process or storage station for wafers said enclosure having a frontal opening and exterior structural features, said robot having a fixed body with an articulating arm having said end-effector that is movable in the vertical (Z), angular e, and radial (R) directions and is connected to a controller having memory and logic sections, said method comprising the steps of:

• (1)—selecting a plurality of said structural features on said enclosure and storing in said controller rough distance and geometrical data defining the location of said features relative to said robot body;
• (2)—programming said controller to cause said robot to first determine the Z-height of said enclosure opening by causing said end-effector to sequentially touch the top surface of a platform structure extending from said enclosure having a known thickness and storing a signal generated by said touching;
• (3)—programming said controller to cause said robot to touch a frontal area of the enclosure structure to determine a rough radial (R) position and storing this position in said controller;
• (4)—programming said controller to touch sequentially structural locations on opposite sides of said enclosure and thereafter to calculate the calibrated angular position of the centerline of the enclosure opening;
• (5)—using said calibrated angular position to determine a more accurate radial (R) position of said end-effector;
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• (6)—determining the yaw angle of said enclosure relative to said end-effector if the enclosure front is not exactly perpendicular to the radial axis of the end-effector.

A method for automatically calibrating the positioning of the end-effector of a wafer handling robot to a precise location relative to a target structure such as a process or storage station for wafers, said robot having a fixed body with an articulating arm with said end-effector at its outer end, said arm being movable in the vertical (Z), angular (⊖) and radial (R) directions and being connected to a machine controller having memory and logic sections, said end-effector having sensor means mounted therein, said method comprising the steps of:

• (1)—selecting a plurality of features on said target structure and storing in said controller rough distance and geometrical data defining the location of said features relative to said robot body;
• (2)—programming said controller to move in the vertical direction while activating said sensor means to determine Z-height measurements of said target structure and storing said measurements in the controller memory;
• (3)—programming said controller to cause said robot to touch a frontal area of said target structure to determine a radial (R) position thereof, and storing this position in said controller;
• (4)—programming said controller to touch sequentially locations on opposite sides of said target structure and thereafter calculating and storing a desired calibrated angular position between the touched sides in said controller;
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• (5)—combining the stored measurements for the Z, R and e axes for establishing a calibrated, precise position of said robot end-effector relative to said structural target.