Wafer metrology technologies
AssigneeFemtoMetrix, Inc.
InventorsViktor Koldiaev, Marc Kryger, John Changala
Life of this patent
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Abstract
Various approaches can be used to interrogate a surface such as a surface of a layered semiconductor structure on a semiconductor wafer. Certain approaches employ Second Harmonic Generation and in some cases may utilize pump and probe radiation. Other approaches involve determining current flow from a sample illuminated with radiation. Decay constants can be measured to provide information regarding the sample. Additionally, electric and/or magnetic field biases can be applied to the sample to provide additional information.
Claims32
A system for optically interrogating a surface, comprising
- a pump optical source configured to emit pumping radiation, the pumping radiation having an average optical pump power;
- a probe optical source configured to emit probing radiation, the probing radiation having an average optical probe power less than the average optical pump power;
- at least one optical detector configured to detect second harmonic generated light generated by at least one of the pumping radiation or the probing radiation, the second harmonic generated light being generated by a semiconductor wafer whose surface is to be interrogated;
- at least one of a shutter, a modulator or a variable optical path that is configured to introduce a variable time offset between the pumping and the probing radiation;
- and
- a processor configured to determine a characteristic of the detected second harmonic generated light,
- wherein the system is configured to obtain a time dependence of the detected second harmonic generated light in less than 10 seconds after applying at least one of the pumping radiation and the probing radiation.
A system for optically interrogating a surface, comprising:
- a pump optical source configured to emit pumping radiation, the pumping radiation having an average optical pump power;
- a probe optical source configured to emit probing radiation, the probing radiation having an average optical probe power less than the average optical pump power;
- at least one optical detector configured to detect second harmonic generated light generated by at least one of the pumping radiation or the probing radiation, the second harmonic generated light being generated by a semiconductor wafer whose surface is to be interrogated;
- and
- a controller configured to obtain information regarding time dependence of the detected second harmonic generated light produced in less than 10 seconds after applying at least one of the pumping radiation and the probing radiation.
A system for optically interrogating a surface, comprising
- a pump optical source configured to emit pumping radiation with variable energy, the pumping radiation having an average optical pump power;
- a probe optical source configured to emit probing radiation, the probing radiation having an average optical probe power less than the average optical pump power;
- an optical detector configured to detect second harmonic generated light generated by at least one of the pumping radiation or the probing radiation, the second harmonic generated light being generated by a semiconductor wafer whose surface is to be interrogated;
- and
- processing electronics configured to:
- obtain information regarding time dependence of the detected second harmonic generated light generated less than 10 seconds after applying at least one of the pumping radiation and the probing radiation;
- and
- detect a region of discontinuity in the second harmonic generated light to determine threshold injection carrier energy as the energy of the pumping radiation is varied.
Dependencies are inferred from the claim text.