Open-Path Cavity Ring-Down Spectroscopy for Simultaneous Detection of Hydrogen Chloride and Particles in Cleanroom...

Area of Science:

• Environmental Science
• Analytical Chemistry
• Semiconductor Manufacturing

Background:

• Cleanroom environments are critical for semiconductor manufacturing, requiring precise monitoring of airborne contaminants.
• Airborne Molecular Contaminants (AMCs) like hydrogen chloride (HCl) can degrade equipment and product yield.
• Particles also pose a significant risk to sensitive manufacturing processes.

Purpose of the Study:

• To develop advanced monitoring techniques for particles and AMCs in cleanrooms.
• To quantify particle levels and hydrogen chloride (HCl) concentrations.
• To enable high-sensitivity detection for improved semiconductor manufacturing integrity.

Main Methods:

• Development of a compact laser sensor utilizing open-path cavity ring-down spectroscopy (CRDS).
• Employment of a 1742 nm near-infrared diode laser for HCl detection via its 2-0 vibrational band.
• Analysis of Mie scattering-induced ring-down time fluctuations for particle quantification.

Main Results:

• Achieved high-sensitivity detection of HCl with an Allan deviation of 0.15 ppb over 15 minutes.
• Demonstrated particle detection at densities as low as ~10^5 m^-3 (diameter > 1 μm) using statistical moments of ring-down distributions.
• Validated the sensor's capability for simultaneous detection of AMCs and particles.

Conclusions:

• The developed CRDS sensor provides a basis for advanced cleanroom monitoring instrumentation.
• Future development can lead to compact, mobile platforms for wafer-level monitoring of both AMCs and particles.
• This technology enhances the integrity and efficiency of semiconductor manufacturing processes.