Patent ID: 7206663

Claim:
A method for calibrating a robot arm by a calibration cassette pod comprising the steps of: providing a cassette pod body and a cassette pod door, said cassette pod body being constructed of a top panel, a bottom panel, two side panels and a front panel defining a cavity therein; providing a first plurality of ribs on an inside surface of said two side panels and said front panel each having a preset depth sufficient for supporting an edge portion of a wafer; mounting an optical detector housing on an opening in said front panel adapted for receiving an optical detector therein, said optical detector comprising a light emission source and a photo diode receiver for determining the position of said edge portion of the wafer; providing a process controller for receiving signals from said light emission source and said photo diode receiver; manually operating said robot arm and loading a wafer into said cavity such that said edge portion of the wafer is positioned in-between said light emission source and said photo diode receiver and in a correct position on top of one of said first plurality of ribs; resetting a reading on said process controller to zero; and automatically operating said robot arm and loading a wafer into said cavity obtaining a new reading on said process controller and determining its deviation from zero.