Tunable Bulk Acoustic Wave Resonator and formation process of wet chemical etching for backside cavity A tunable Bulk Acoustic Wave resonator made tunable by  magneto-elastic mechanism and is obtained by integrating a magnetostrictive material inside the BAW resonator. The top electrode, piezoelectric layer and bottom  electrode of the BAW resonator are patterned in the pentagonal shape which reduces the spurious resonance through the symmetry reduction. This approach splits the  resonance mode spectrum into a larger number of weakly coupled modes rather than a smaller number of strongly coupled modes. The tunable BAW resonator is  tunable, reconfigurable, compact, lightweight, and cost-effective nature makes it ideal for a wide range of applications such as usage in tunable band-pass filters,  duplexers, tunable oscillators, magnetic field sensors, and energy harvesters. The magnetic tuning mechanism is non-invasive and retuning technique; wherein, BAW  has small size and low power consumption, coupled with robustness and long-term stability, ensure efficient and reliable performance over extended periods.