Patent ID: 6815958
Filing Date: 2004-11-09
Classification: G01B

Abstract:
An apparatus for measuring thickness and deviations from the thickness of a film on a substrate, wherein one of said film and said substrate is a conductive body and the other is a nonconductive body, said apparatus comprising:sensor means comprising a resonance oscillating circuit characterized by inherent inductance, inherent capacitance, and an inherent resonance frequency; a high-frequency AC generator with an amplitude modulator connected to said sensor means; and an amplifier connected to said sensor means; a measurement unit connected to said sensor; said resonance oscillating circuit having such a relationship between said inherent inductance and inherent capacitance that provides a capacitive coupling via a capacitance induced between said sensor and said film at a distance between said sensor and said film at which said capacitance is on the same order as said inherent capacitance of said oscillating circuit as a whole.