Method for monitoring the position of a semiconductor processing robot

Abstract

A robotic positioning system that cooperates with a sensing system to correct robot motion is provided. The sensing system is decoupled from the sensors used conventionally to control the robot's motion, thereby providing repeatable detection of the robot's true position. In one embodiment, the positioning system includes a robot, a controller, a motor sensor and a decoupled sensor. The robot has at least one motor for manipulating a linkage controlling the displacement of a substrate support coupled thereto. The motor sensor is provides the controller with motor actuation information utilized to move the substrate support. The decoupled sensor provides information indicative of the true position the substrate support that may be utilized to correct the robot's motion.

1 . A method for correcting robotic motion, comprising:
 sensing an actual position of a robot at a calibration position with a sensor decoupled from the robot;   comparing the actual position of the robot with a calculated position corresponding to the calibration position; and   compensating for differences in the actual position and calculated position.   
   
   
       2 . The method of  claim 1 , wherein the sensing further comprises:
 moving the robot laterally to a taught position; and   causing the sensor to change state before the robot reaches the taught position.   
   
   
       3 . The method of  claim 2 , wherein the sensing further comprises:
 moving a blade of the robot to a taught position; and   causing the sensor to change state.   
   
   
       4 . A method for correcting robotic motion, comprising:
 obtaining a metric indicative of an actual position of a blade of a robot at a first position with a sensor decoupled from the robot;   comparing the actual position of the robot with an expected position derived from a sensor coupled to one or more robot actuators; and   correcting robot motion in response to differences between the actual position and expected position.   
   
   
       5 . The method of  claim 4 , wherein the obtaining further comprises:
 moving the blade to a taught position; and   causing the sensor to change state.   
   
   
       6 . The method of  claim 4  further comprising:
 obtaining a metric indicative of an actual position of a blade of a second robot at the first position with the sensor;   comparing the actual position of the second robot with an expected position derived from a sensor coupled to one or more second robot actuators; and   correcting second robot motion in response to differences between the actual position and expected position.