Keywords
Citation
Hollingum, J. (2000), "Calibration for wafer transfer robot", Industrial Robot, Vol. 27 No. 6. https://doi.org/10.1108/ir.2000.04927fad.016
Publisher
:Emerald Group Publishing Limited
Copyright © 2000, MCB UP Limited
Calibration for wafer transfer robot
Keywords Robots, Calibration
Applicant: Berkeley Process Control Inc. (US)Patent number: US6075334Publication date: 13 June 2000Title: Automatic calibration system for wafer transfer robot
It is a general object of the present invention to provide a method and apparatus for automatically calibrating or teaching a wafer handling robot in conjunction with its control system so that it will operate reliably with reproducibility for a multitude of cycles and within close tolerances to manipulate wafers from cassette holders to various process stations without any damage to wafers. The objects are accomplished by a system consisting of a robot with three degrees of freedom in the radial, angular, and vertical directions. The robot, which is connected to a machine controller having a memory section and logic circuitry, has a movable robot arm which can be extended to reach a preselected location such as a cassette containing semiconductor wafers and one or more of a plurality of processing stations. At the outer end of the robot arm is a wand having a wafer engaging and retaining means such as an edge grip device or a vacuum port that enables it to pick-up, place and transport wafers. In order to perform these actions, the robot must have precise knowledge of the R, .theta. and Z positions at which to pick-up and place wafers at both locations. The present invention provides a means for automatically determining or calibrating the various required robot positions with no operator intervention. The controller has a memory section which is supplied with initial data including nominal R, .theta. and Z pick-up and drop-off positions of the wafers at the process stations and cassettes of the system. Also, the controller memory is provided with vital dimensional characteristics of the robot and the process stations and cassettes that are serviced by the robot. The controller is connected to an I/O system which receives sensor signals from the robot arm, the process stations and cassettes as well as from the robot motors.
Jack Hollingum