Microstructure-Driven Loss Mechanisms and Tensor-Based FEM Calibration

Area of Science:

• Materials Science
• Mechanical Engineering
• Nanotechnology

Background:

• Silicon carbide (SiC) is vital for advanced MEMS operating in harsh conditions.
• Conventional models assume isotropic damping, failing to capture directional energy dissipation in heteroepitaxial 3C-SiC.

Purpose of the Study:

• To investigate anisotropic damping mechanisms in heteroepitaxial 3C-SiC double-clamped beam resonators.
• To develop and validate a 6x6 loss-factor tensor model for accurate Q-factor prediction in MEMS.

Main Methods:

• Implemented a full 6x6 loss-factor tensor in Voigt notation within COMSOL Multiphysics.
• Analyzed effects of film thickness, Young's modulus, and residual stress on resonator properties.
• Extracted experimentally calibrated anisotropic loss-factor matrices via least-squares fitting.

Main Results:

• The anisotropic model significantly reduces Q-factor prediction errors (<1%) compared to isotropic models.
• Model accuracy is particularly enhanced for SiC films thicker than 600 nm.
• Found a negative correlation between the Frobenius norm of loss-factor matrices and resonance frequency.

Conclusions:

• Accurate treatment of directional energy dissipation is essential for designing high-Q resonators and sensitive strain sensors.
• The anisotropic tensor model provides superior performance for MEMS applications utilizing heteroepitaxial 3C-SiC.
• Findings are critical for developing next-generation geophysical monitoring devices.