Measurement system and method based on femtosecond laser
AssigneeKorea Advanced Institute of Science and Technology
InventorsYoung-Jin KIM, Dae Hee KIM, Jun Hyung PARK
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Abstract
A measurement system comprises a femtosecond laser; an optical mask configured to block a central portion of a beam output from the femtosecond laser to generate an annular beam; an objective lens configured to focus the annular beam onto a measurement target; a scanner configured to perform depth-direction scanning of the measurement target by controlling a focal point of the annular beam; a detector configured to detect third-harmonic generation (THG) signals generated from the measurement target during the depth-direction scanning; and a computing device configured to calculate a physical thickness of the measurement target using a distance between two points at which the THG signals are detected.
Claims14
A measurement system, comprising:
- a femtosecond laser;
- an optical mask configured to block a central portion of a beam output from the femtosecond laser to generate an annular beam;
- an objective lens configured to focus the annular beam onto a measurement target;
- a scanner configured to perform depth-direction scanning of the measurement target by controlling a focal point of the annular beam;
- a detector configured to detect third-harmonic generation (THG) signals generated from the measurement target during the depth-direction scanning;
- and
- a computing device configured to calculate a physical thickness of the measurement target using a distance between two points at which the THG signals are detected.
A wafer measurement method, comprising:
- blocking a central portion of a beam output from a femtosecond laser to generate an annular beam;
- focusing the annular beam onto a surface of a wafer and performing depth-direction scanning of the wafer by controlling a focal point of the annular beam;
- detecting third-harmonic generation (THG) signals generated from the wafer during the depth-direction scanning;
- and
- calculating a physical thickness of the wafer using a distance between two points at which the THG signals are detected.
Dependencies are inferred from the claim text.