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Photoresist thickness measurement using laser-induced fluorescence
Applied Optics
|June 12, 2010
Summary
This study introduces a novel fluorescence-based method to precisely measure photoresist film thickness. The technique utilizes laser-induced fluorescence for accurate, small-area thickness determination in microelectronics fabrication.
Area of Science:
- Materials Science
- Optical Metrology
- Semiconductor Manufacturing
Background:
- Accurate measurement of thin films is critical in microelectronics.
- Existing methods for small-area thickness measurement can be complex or destructive.
- Photoresist thickness directly impacts device performance and yield.
Purpose of the Study:
- To develop a non-contact, optical technique for measuring photoresist film thickness.
- To establish a calibration method correlating fluorescence to thickness.
- To assess the accuracy and limitations of the proposed measurement technique.
Main Methods:
- Inducing fluorescence in photoresist using a focused 497 nm laser.
- Measuring the peak fluorescence emission (~600 nm).
- Establishing a calibration curve by correlating known thicknesses with fluorescence intensity.
Main Results:
- A linear relationship was observed between photoresist thickness and fluorescence intensity.
- The technique allows for thickness measurement of small areas.
- The accuracy of the measurement was evaluated based on laser spot size and signal-to-noise ratio.
Conclusions:
- The proposed fluorescence-based technique offers a viable method for precise photoresist thickness measurement.
- This technique has potential applications in semiconductor process control and quality assurance.
- Further optimization could enhance measurement speed and resolution.
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