Self teaching robotic carrier handling system

Abstract

Briefly, a preferred embodiment of the present invention includes a wafer carrier buffer for storage of a plurality of carriers containing wafers either waiting to be taken for processing in an adjacent wafer processing system, or waiting to be taken from the buffer following the processing. The buffer has a sliding carrier first input apparatus for taking a carrier from outside the buffer through a buffer input door and into the buffer interior. A buffer controller is included for directing robotic apparatus to take the carrier from the input apparatus and place it on a selected one of a plurality of carrier storage locations, and from a carrier storage location to a first output for delivery of wafers to processing. The robotic apparatus also delivers an empty carrier to a second input apparatus for receiving wafers from the processing area, and for delivery of a carrier with processed wafers to a second sliding output apparatus for removal from the buffer through a buffer output door. The controller is programmed to direct an automatic calibration of all of the carrier storage locations and the input and output positions. The robotic apparatus includes a sensor for detecting the position of a flange on a calibration fixture that is placed by the robot at a carrier storage location. The flange is accurately positioned on the fixture to correspond to a similar flange on each carrier that is used to engage with a tool on the robotic apparatus for moving the carrier. The calibration is preferably done by directing the robotic apparatus to place the calibration fixture at a location in need of calibration and then sensing the precise position of the fixture flange with the sensor apparatus. The controller then calculates the coordinates required to place a carrier accurately in that location. This process is repeated for each carrier storage location and the input and output locations.