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This work presents an electromechanical finite element analysis for a proposed MEMS piezoelectric vibration energy harvester. The structure of the MEMS energy harvester consists of a basic cantilever beam with a clamped end mass and a spring net which can enhance the reliability of the device. Aluminum nitride thin film is applied as the piezoelectric function material. The proposed MEMS device is also fabricated, packaged and characterized to determine its performance. The spring net structure design is proven to increase the yield of the MEMS energy harvester chips during transportation. Three dimensional electromechanical finite element model coupled the solid mechanics physics and electrostatics physics is built to simulate the piezoelectric effect. The simulated results and the experimental measured data are in close agreement, which verified the prediction of the finite element model. The validation of the model indicate that the finite model can instruct the design of an ideal MEMS piezoelectric device in short period at a low cost.

In this paper, we proposed a novel non-solenoid structure to realize high Q on-chip inductor based on MEMS techniques. It aims to reduce the resistance loss by parallel turns while increase the inductance by the self-inductance of the inner and outer copper wire columns and the mutual inductance between the same flow directions. The inner and outer copper wire columns are spaced apart as much as possible without the reverse flow mutual inductance subtraction. Finite element method was applied to analyze the performance of the designed inductor. The novel inductor can significantly improve the Q value (peak Q= 39 @ 2.03 GHz) which nearly 180% higher than that of traditional 8-turns solenoid inductor, and nearly 450% higher than that of a planar spiral inductor at the same feature size. We also raised several solutions to solve the low inductance problem due to the parallel connection. In addition, the self-resonant frequency is greater than 15 GHz which makes our inductor adaptable to a wider spectrum of applications.

In this paper, we proposed a vertical spiral structure to realize high performance (high Q and high L) on-chip inductor based on MEMS technology. It aims to reduce the substrate loss by the approach of 3D vertical integration so that the quality factor of the on-chip inductors could be improved. In order to verify and explore the improvement of the quality factor of the vertical spiral solenoid structure, finite element method was used to analysis the performance of designed inductor, and an optimal solution was raised through modeling and simulation by commercial software HFSS. Combining the thermal oxidation process level, we tried to isolate silicon by 10um silicon dioxide isolation layer. Simulation results show that more than 10um silicon dioxide isolation layer no longer improves the inductive performance. The simulation results show that the same scalar-isolated vertical spiral inductors provide superior performance (peak Q = 32 @ 7 GHz, L=4nH). Compared with ordinary silicon planar inductors, the quality factor Q increased 30%, inductance L increased 100%. In addition, self-resonant frequency is greater than 10 GHz which makes our inductor could adapt to a wider spectrum of applications.