Accurate characterization of SiO2 thin films using surface acoustic waves

Area of Science:

• Materials Science
• Acoustics
• Thin Film Technology

Background:

• Understanding the acoustic properties of thin films is crucial for device applications.
• Silicon dioxide (SiO2) is a widely used material in microelectronics and photonics.

Purpose of the Study:

• To investigate the acoustic properties of SiO2 thin films.
• To determine the phase velocity dispersion and extract mechanical properties (density, elastic constants) of SiO2 films.

Main Methods:

• Utilized laser ultrasonics and differential delay lines to measure phase velocity dispersion.
• Employed plasma-enhanced chemical vapor deposition (PECVD) and physical vapor deposition (PVD) for SiO2 film deposition.
• Performed finite element simulations to extract material properties from experimental data.

Main Results:

• Successfully determined the phase velocity dispersion of SiO2 thin films on LiNbO3.
• Extracted density (p) and elastic constants (c11, c44) with at least 4% accuracy.
• Developed two novel methods to enhance phase velocity accuracy, particularly for PVD films with thickness variations.

Conclusions:

• The study provides accurate acoustic characterization of SiO2 thin films.
• The proposed methods offer improved accuracy for thin film property determination.
• This research contributes to the precise engineering of materials for acoustic and electronic devices.