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Film bulk acoustic wave resonators (FBARs) with relatively high Q-factor are considered good candidates to be used in the RF module of chip-scale atomic clocks (CSACs). In order to simulate and analyze the resonant properties, the Mason equivalent circuit of the FBAR device is introduced, which consists of five parts including top electrode layer, low temperature silicon oxide layer, piezoelectric layer, bottom electrode layer and a composite support structure layer. With the practical processing conditions considered, the piezoelectric layer with a reasonable thickness of 1.30um is selected to achieve a FBAR device with resonant frequency 4.60GHz and Q-factor 278 by the simulation and analysis. In order to further improve the Q-factor, SiO2 thin films with thicknesses from 0.10um to 0.50um placed between the top electrode and piezoelectric layer are introduced. However, as the SiO2 thin film is introduced, the resonant frequency of the FBAR device will drop. In order to keep the resonant frequency fixed to 4.60GHz, the thickness of the piezoelectric layer is adjusted. Finally, the FBAR device resonating at 4.60GHz with Q-factor 627 is achieved, the thicknesses of the SiO2 film and piezoelectric layer of which are 0.20um and 0.69um respectively. The Q-factor of the FBAR device improves about 350, and the FBAR device is expected to be used in CSACs.

AlN films were deposited by RF magnetron sputtering on the SiO2 films with different thickness. Preferred orientation, grain size, surface roughness and grain growth of the AlN films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM) and field-emission scanning electron microscopy (FESEM). It's found that when the thickness of SiO2 films are 100 nm and 200 nm, the AlN films have characteristics of good C-axis preferred orientation, good surface roughness and vertical grain growth, which are suitable for application in thin film bulk acoustic wave resonators (FBARs). When the thickness of SiO2 film is 300 nm, although the AlN film has characteristics of good C-axis preferred orientation and surface roughness, the grain growth is tilted, which is not suitable for application in the FBARs.

Modern manufacturing systems require timely and efficient production tasks. Any mistakes can have serious consequences which effect the production process obviously. The supply of goods is the beginning of the production process, ensuring that production can proceed normally. Using mobile robots for transportation and supply of production lines can achieve automatic manufacturing. We studied the use of multiple mobile robots to supply multiple production lines. Robots need to return to warehouse when no goods exist. This problem is called a multi-mobile robots and multi-trips feeding scheduling problem. We constructed a mathematical model describing multi-mobile robots and multi-trips feeding scheduling problem, and the objective function is to minimize the transportation cost and waiting cost. To solve this problem, we proposed an improved hybrid genetic algorithm, where a strategy of mixing improved genetic algorithm and tabu search algorithm is adopted to find robots with reasonable routes. Combining genetic algorithm with tabu search algorithm can improve the route planning effect and find a lower cost solution. In the experimental part, it is verified that the proposed algorithm could effectively find reasonable ways for robots to provide services. We also put forward suggestions for the scenarios of using robots in actual production.