Research on the Key Technologies of PZT Microcantilever for Scanning Plasma Etching
|School||Anhui University of Engineering|
|Course||Mechanical Manufacturing and Automation|
|Keywords||Scanning Plasma Etching PZT microcantilever residual stress Taguchi method vibration control|
With the development of the micro/nano-technologies, fabrication technology on the multi-species and small batches of micro/nano-device has been widely applied. Thin film etching is one of the key technologies in fabrication of the micro/nano-device. Due to its advantages of high efficiency and good selectivity, plasma etching has been widely applied in thin film etching. Since macroscale plasma applied on the whole surface of substrate, multiple masks steps are needed during the pattern of thin film by plasma etching. The mask steps added in the fabrication process may increase cost and decrease efficiency. Microplasma is microscale plasma has feature size below lmm. Due to its high plasma density, non-thermal equilibrium, high operation pressure; microplasma has been widely used in display, chemical, film deposition and etching etc., al. In preliminary study, we have developed a scanning plasma etching method based on PZT microcantilever integrated with microplasma reactor. With integrate plasma etching and Scanning probe, Scanning Plasma Etching will provide a new fabrication method for multi-species and small batches of micro/nano-device. The PZT microcantilever is the key component of scanning plasma etching system. Self actuation and self sensing of microcantilever are realized through PZT thin film, so the performance of PZT microcantilever is very important in the realization of the scanning plasma etching system.According to subject topic, the contents of this thesis can be summarized as:(1) The function of self actuation and self sensing of microcantilever is realized by the piezoelectric and converse piezoelectric effect of PZT. According to the theory of piezoelectricity and mechanics of materials establish the theoretical model of multicantilever, and then analysis relationship between structure parameters and properties and performance of microcantilever control, which will provide theoretical model for future works.(2) The residual stress of thin films in multilayer PZT microcantilever generated during the fabrication process will lead to bending or crack after cantilever releasing. The analysis model of microcantilever with residual stress is developed by replace with equivalent thermal stress based on thin-walled beam theory. In view of minimum bending principle, the optimal thickness of multiple layers in microcantilever is obtained through finite element analysis (FEA) and Taguchi method. Finally, the resonance performances include resonance modal, resonance frequency and quality factor of Mir cantilever under variable stress is study by FEA.(3) Based on the theoretical analysis, the system model of the microcantilever can be established by finite element method, and also confirm the matrix (which is include mass, stiffness and damping), then using Guyan method to reduce the freedom number of system state matrix, and ensure corresponding matrix value for future study. Finally, the fabrication process of the microcantilever is developed. (4) By using MATLAB/SIMULINK software set up the microcantilever system control model, including this model simulated features of vibration analysis, which can understand the basic vibration characteristics of PZT microcantilever and can test the control algorithm for analyze the resonance information of the piezoelectric layer as the microcantilever of actuator or sensor. Finally using the LABVIEW and DAQ data acquisition system to analysis of the PZT power driven of double-layer PZT, and then obtain feedback control results.