Method for measuring thin metal films
AssigneeKoninklijke Philips Electronics N.V.
InventorAlex Maznev
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Abstract
A method and system for measuring properties of a sample are disclosed. At least one source of excitation radiation is used to irradiate the sample's surface. This excites multiple acoustic modes within the sample. A probe source of radiation diffracts off the acoustic modes to generate a signal beam. The signal beam is detected and analyzed to yields a signal waveform, from which a Fourier Transform spectrum is derived. The Fourier Transform spectrum features frequencies corresponding to the multiple acoustic modes. Analysis of the spectrum yields measurements of the sample's properties.
Claims31
A method for determining properties of a multilayer structure, comprising the steps of:
- generating at least two excitation pulses:
- forming an excitation pattern on or in the structure, using the two excitation pulses, that causes a modulation response by at least a portion of the structure;
- detecting a signal based upon the modulation response, the signal including at least two sub-component frequency values;
- and
- analyzing the at least two sub-component frequency values of the signal to determine at least two properties of the structure by analyzing one of (1) more than one acoustic mode of the signal and (2) a time constant indicating decay of the signal.
A method for determining a property of a structure, comprising the steps of:
- generating at least two excitation pulses;
- forming an excitation pattern on or in the structure, using the two excitation pulses, that causes a modulation response by at least a portion of the structure;
- detecting a signal based upon the modulation response, the signal including at least one frequency value and at least one harmonic value of the at least one frequency value;
- and
- measuring the at least one harmonic value of said at least one frequency value to the determine the property of the structure.
An apparatus for determining properties of a multilayer structure, comprising:
- at least one source of excitation radiation;
- a measurement system capable of forming an excitation pattern on or in the structure, using the excitation radiation, that causes a modulation response by at least a portion of the structure;
- a detector, coupled to the measurement system, capable of detecting a signal based upon the modulation response, the signal including at least two sub-component frequency values;
- and
- an analyzer, coupled to the detector, capable of determining at least two properties of the structure in accordance with the respective at least two sub-component frequency values of the signal.
An apparatus for determining a property of a structure, comprising:
- at least one source of excitation radiation;
- a measurement system capable of forming an excitation pattern on or in the structure, using the excitation radiation, that causes a modulation response by at least a portion of the structure;
- a detector, coupled to the measurement system, capable of detecting a signal based upon the modulation response, the signal including at least one frequency value and at least one harmonic value of the one frequency value;
- and
- an analyzer coupled to the detector, capable of measuring the at least one harmonic value to determine the property of the structure.
A memory medium including code for controlling, when executed, an analyzer for an apparatus for determining at least two properties of a multilayer structure, the code comprising:
- code for receiving a signal based upon a modulation response by at least a portion of the structure caused by an excitation pattern on or in the structure, the signal including at least two sub-component frequency values;
- and
- code for determining at least two properties of the structure in accordance with the signal.
A memory medium including code for controlling, when executed, an analyzer for an apparatus for determining at least one property of a structure, the code comprising:
- code for receiving a signal based upon a modulation response by at least a portion of the structure caused by an excitation pattern on or in the structure, the signal including at least one frequency value and at least one harmonic value of the at least one frequency value;
- and
- code for analyzing a measurement of the at least one harmonic value to determine the property of the structure.
A method for determining an electrical resistivity of a film in a sample, comprising the steps of:
- irradiating the sample with at least one optical excitation pulse to generate a response characterized by an acoustic wave and a decaying component;
- irradiating the sample with an optical probe beam to generate a probe beam that is modulated by the acoustic wave and decaying component;
- detecting the probe beam to generate an electrical signal waveform;
- analyzing the electrical signal waveform to characterize the acoustic wave and the decaying component;
- and
- determining the electrical resistivity by analyzing the decaying component.
A method for determining the thickness of two films in a sample, comprising the steps of:
- irradiating the sample with at least one optical excitation pulse to generate a response characterized by an acoustic wave component and a decaying component;
- irradiating the sample with an optical probe beam to generate a probe beam that is modulated by the acoustic wave and decaying components;
- detecting the probe beam to generate an electrical signal waveform;
- analyzing the electrical signal waveform to characterize the acoustic wave and the decaying components;
- determining the thickness of at least one film by analyzing the acoustic wave component;
- and
- determining the thickness of at least one film by analyzing the decaying component,
- wherein the analyzing step further comprises comparing the electrical signal waveform to a mathematical function and the mathematical function comprises an exponential function.
Dependencies are inferred from the claim text.