A Comprehensive Thermal Stability Analysis of D-BAW Structures Employing Dry Film Bonding Materials

In the present study, the thermal stability of two distinct dry film materials within a double-side-patterning bulk acoustic wave (D-BAW) structure was thoroughly investigated and assessed. The empirical data indicated that several material properties, including the coefficient of thermal expansion (CTE), thermogravimetric transition temperature (TG), Young’s modulus, among others, play a critical role in determining the overall thermal robustness of the D-BAW device. The results underscored a clear correlation: when the CTE value of the dry film more closely matches that of silicon, combined with a higher TG temperature and an increased Young’s modulus, the variation in the filter’s performance curve before and after undergoing temperature cycling test (TCT) is significantly minimized. This suggests that selecting dry film materials with reduced CTE mismatch to Si, enhanced thermal resistance (higher TG), and improved mechanical stiffness (larger Young’s modulus) leads to better thermal stability and consistent filtering capabilities under fluctuating temperature conditions.