Method and device for measuring the thickness of opaque and transparent films

US6348967B1 · kind B1 · utility

Assignee

• Active Impulse Systems, Inc. · US

Inventors

• Keith A. Nelson · Newton, US
• John A. Rogers · Champaign, US
• Matthew Banet · Del Mar, US
• John Hanselman · Needham, US
• Martin Fuchs · Uxbridge, US

Key dates

• Filing date: May 11, 2000
• Grant date: Feb 19, 2002
• Expiry date: May 11, 2020

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N2291/0423
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A method for determining the thickness of a thin sample is described. The method includes the step of exciting time-dependent acoustic waveguide modes in the sample with an excitation radiation field. The acoustic waveguide modes are detected by diffracting probe radiation off a ripple morphology induced on the sample's surface by the acoustic waveguide modes. The diffracted probe radiation is then analyzed to measure phase velocities or frequencies of the acoustic waveguide modes. A thickness of the thin sample is determined by comparing the measured phase velocities or frequencies to the phase velocities or frequencies calculated from a mathematical model.