Method for adjusting contact position of lift pins, method for detecting contact position of lift pins, and substrate placement mechanism

Abstract

A method for adjusting a contact position of lift pins in a substrate placement mechanism is provided. The substrate placement mechanism includes a substrate placement table and a substrate lifting mechanism having lift pins and a driving mechanism, wherein the contact position of the lift pins is a height position where tip ends of the lift pins get in contact with the substrate. The method comprises creating torque waveforms, for a plurality of voltages, indicating temporal changes of a torque of the motor while moving the tip ends of the lift; obtaining from the plurality of torque waveforms a contact point when the lift pins get in contact with the substrate and calculating the contact position from the contact point and a speed of the motor; determining whether the contact position is within an appropriate range; and automatically adjusting the contact position when the contact position is not within the appropriate range.