Apparatus and method for automated wafer handling

Abstract

In order to manipulate semiconductor wafers with high functional reliability, a tactile sensor based wafer handling apparatus designed to attach to a commercially available industrial robotic arm is herein described. The apparatus has three rod-like projections called fingers, one finger of which is extendable, the other which are fixed. All fingers are instrumented with strain gauge sensors in order to allow the monitoring of all forces applied to the fingers during wafer handling operations. All sensors provide proportional data. The wafer handling apparatus enables a monitoring computer to direct the motions of a satisfactorily equipped robot arm to operate in the following modes of operation. Force controlled grasping of the wafer can be provided to insure adequate grasp for transport and to limit forces exerted on the wafer. Force monitoring while releasing a wafer can be provided to insure safe hand off to another device or surface thus minimizing the likelihood of dropping a wafer. Proportional adaptive control of robot motions necessary can be provided to align wafers extremely closely to process carrier surfaces. Proportional adaptive control of robot motions necessary to guide the gripping apparatus can be provided for balanced contact with the edge of a wafer. Force monitoring can be provided for the purpose of detecting collisions with object or humans during transport of a wafer.