Model of Quality Factor for (111) 3C-SiC Double-Clamped Beams

Area of Science:

• Materials Science
• Semiconductor Physics
• Mechanical Engineering

Background:

• Silicon carbide (SiC) exhibits a high Young's modulus, beneficial for high-frequency and high-quality factor (Q-factor) resonant microelectromechanical systems (MEMS).
• Understanding the Q-factor is crucial for optimizing the performance of SiC-based MEMS devices, particularly those utilizing double-clamped beams.

Purpose of the Study:

• To determine and model the Q-factor of micromachined 3C-SiC films on silicon substrates.
• To investigate the impact of crystallographic defects at the 3C-SiC/Si interface on the Q-factor.

Main Methods:

• Experimental data from existing studies and newly fabricated thicker SiC samples were integrated.
• Analytical modeling (Romero's model) and numerical modeling (COMSOL) were employed to analyze the Q-factor.
• The influence of film thickness and interface defects was assessed.

Main Results:

• Experimental data, including thicker samples, align with the theoretical model.
• Crystallographic defects at the 3C-SiC/Si interface demonstrably affect the Q-factor in both analytical and numerical models.
• Optimal performance of double-clamped beams requires 3C-SiC layers exceeding 600 nm in thickness.

Conclusions:

• The developed model accurately predicts the Q-factor for 3C-SiC resonant devices.
• Minimizing interface defects and utilizing thicker SiC films are key for enhancing MEMS device performance.
• This research provides critical insights for designing high-performance SiC MEMS.