DEVICE FOR DETECTING END POINT OF ION MILLING PROCESS

PURPOSE:To enable detect a end point of an etching by measuring a current flowing into a wafer stage during an ion milling process. CONSTITUTION:A wafer stage 1 insulated by an insulator 2 is provided opposing to a chamber wall 5 of an ion milling apparatus while the wafer stage 1 is made smaller than a wafer 6 on to be exposed to ion during ion milling process. A bias power supply 3 supplys bias voltage to be supplied for the wafer stage 1. At this time, the bias voltage can be set up to be converted either into positive or negative. Furthermore, can ampere meter to measure the current flowing from the wafer stage 1 is provided. The wafer 6 is placed on the wafer stage 1 insulated from the chamber wall of ion milling apparatus to supply the wafer stage 1 with bias voltage for measuring the current flowing from the wafer stage 1 during ion milling process. Through these procedures, the current will be changed at an end point of etching so that the end point of etching can be detected.