Profilometry of thin films on rough substrates by Raman spectroscopy

Area of Science:

• Materials Science
• Nanotechnology
• Optics

Background:

• Thin films are crucial in semiconductor devices, but their precise characterization on rough substrates is challenging.
• Light-absorbing thin films can interfere with optical characterization techniques like Raman spectroscopy.

Purpose of the Study:

• To develop a contactless method for precise thickness profiling of thin films on rough substrates.
• To demonstrate the technique for amorphous silicon films used in silicon heterojunction solar cells.

Main Methods:

• Utilizing the signal attenuation effect of light-absorbing thin films on Raman spectroscopy.
• Employing spatially-resolved Raman measurements for thickness mapping.

Main Results:

• Achieved high-precision thickness mapping of amorphous silicon stripes on rough crystalline silicon.
• Demonstrated a thickness detection limit below 1 nanometer and spatial resolution down to 500 nanometers.
• Showcased applicability for thin layers on Raman/photoluminescence-active substrates and single-layer counting in 2D materials.

Conclusions:

• The developed Raman-based technique offers a non-destructive and highly accurate method for thin film characterization.
• This method has broad applicability in semiconductor manufacturing and advanced materials research, including 2D materials.