Thin film process monitoring techniques using acoustic waves
First Claim
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1. A system for measuring thickness of at least one film on a substrate, such constituting a composite unit, said film and substrate having an interface, said system comprising:
- means including a buffer rod having an end shaped to make Hertzian contact with said composite unit for propagating a high frequency acoustic wave through said composite unit, said acoustic wave generating reflected echo waves at the interfaces between the buffer rod and composite, between the composite and air, and between the film and substrate;
means for receiving said echowaves and generating output signals; and
means for processing said output signals to give a film thickness value.
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Abstract
A system and method is disclosed for measuring thickness of at least one film on a substrate by propagating an acoustic wave through the film on a substrate such that echo waves are generated and received by a transducer. An output signal is generated and processed to give a thickness value. The thickness valve is obtained from the time lapse between the propagated wave and receipt of the echo wave; by the frequency domain of the echo wave; or the phase of the echo wave.
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Citations
17 Claims
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1. A system for measuring thickness of at least one film on a substrate, such constituting a composite unit, said film and substrate having an interface, said system comprising:
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means including a buffer rod having an end shaped to make Hertzian contact with said composite unit for propagating a high frequency acoustic wave through said composite unit, said acoustic wave generating reflected echo waves at the interfaces between the buffer rod and composite, between the composite and air, and between the film and substrate; means for receiving said echo waves and generating output signals; and means for processing said output signals to give a film thickness value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus for measuring the thickness of at least one film on a substrate, such constituting a composite unit, said film and substrate having an interface, said apparatus comprising:
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a buffer rod having one end shaped to make a Hertzian contact with said composite unit; a transmitting transducer in communication with the other end of said buffer rod for propagating an acoustic wave through said composite unit, said propagating acoustic wave reflecting off the interface between said buffer rod and composite unit and off of said interface between said film and said substrate to generate echo waves; a receiving transducer for receiving said echo waves; means for receiving said echo waves and generating an output signal representative between the time lapse between said echo waves; and means for processing said output signal to give a thickness value.
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10. A method for measuring the thickness of at least one film on a substrate, such constituting a composite unit, said film and substrate having an interface, said method comprising the steps of:
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propagating a high frequency acoustic wave into and through said composite unit by a Hertzian contact, said acoustic wave reflecting off the Hertzian contact-composite unit interface, said interface between said film and said substrate, and the interface between the composite unit and air to generate echo waves; receiving said echo waves and generating output signals; and processing said output signals to give a film thickness value. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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Specification