Perceptron, Inc.

Frederick P LaPlant

Jeffrey S White

John W Dixon

In a measurement system wherein time-varying physical signals containing frequency information related to a physical parameter of an object are measured to obtain corresponding time-varying measurement signals, a method and system are disclosed for processing the measurement signals to obtain a value for the physical parameter by first extracting the frequency information from the measurement signals. The frequency information includes at least one desired frequency. The physical signals are electromagnetic signals. The object is a film such as a layer formed on a substrate, the physical parameter may be thickness of the layer.

Method and system for processing measurement signals to obtain a value for a physical parameter

In a measurement system wherein time-varying physical signals containing frequency information related to a physical parameter of an object are measured to obtain corresponding time-varying measurement signals, a method and system are disclosed for processing the measurement signals to obtain a value for the physical parameter by first extracting the frequency information from the measurement signals. The frequency information includes at least one desired frequency and its amplitude and decay rate. Then, the frequency information is converted to a value for the physical parameter. The measurement signals are discrete time ultrasonic signals. Extraction is performed by transforming the ultrasonic signals to a Z-domain and converting at least one zero or pole in the Z-domain to the at least one frequency and its decay rate.

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Ann Arbor, MI, United States of America

Frederick P LaPlant