Frequency measuring device, polishing device using the same and eddy current sensor

摘要: A frequency measuring device capable of accurately detecting an end point polishing a semiconductor wafer by obtaining measurement result highly in short period time. FC, which measures the measured signal comprises counting section including plurality n-nary counters, time reference circuit outputs for every predetermined interval, and gate circuits whose are connected to inputs counters. The receive at first input intervals second input. With this structure, supplies interval.