Self teaching robotic wafer handling system

Abstract

A wafer handling apparatus having input and output robotic systems directed by a programmed controller. Each system has components including a robot, a twist and rotate, and a carrier and automated carrier rail. The input system is for removing wafers from their wafer pod, placing them in the carrier and transporting them via the rail to a wafer processing area. The output system performs the reverse operation, taking wafers from a carrier following processing and placing them in a pod. Each robot includes a plurality of interconnected, articulated cantilevered arms. The last one of the arms has a wand on one end and a laser emitter detector on the other end, and operates in cooperation with the controller to provide location detection of system components. The controller also includes circuitry for sensing contact of the wand with an object by measuring the increased robot motor torque occurring upon contact. The controller is pre-programmed with approximate physical dimensions of the system components and their relative positions. The controller is additionally programmed to automatically perform a precision calibration/teaching routine to gather more precise location data. The process of precision teaching/calibration begins by placing a pod calibration fixture on a pedestal. The controller then directs the input robot to sense the fixture position, which gives the controller precise data relating to the position of a pod on the pedestal. The robot then senses the position of the twist and rotate components. The process begins by sensing the height of two arms of the twist and rotate, and the controller adjusts the arm heights until they are level. The controller then directs the robot to sense the R and &thgr; dimensions of the twist and rotate, and these precise dimensions are saved in the controller.