Research On Frequency Modulation Process Of AT Cut Quartz Crystal Resonator By Magnetron Sputtering Technique

Quartz crystal resonator has been widely used in time and frequency measurement, communications, remote control and telemetry, global positioning technology and other electronic devices as a core component of the oscillator. With the electronic equipment of high precision, high-stability quartz crystal resonator increase in demand, the vacuum evaporation coating process as a current mainstream process of quartz crystal resonator electrodes thin-film preparation technology exist technology bottlenecks in the preparation of high precision and high stability quartz crystal resonator because the binding force of chip and thin film is not strong, step coverage capacity is weak, precision control is difficult, technical complexity is higher and so on. With the magnetron sputtering technology development, especially the development of sputtering power, it is possible to use the magnetron sputtering technology for high precision and high stability quartz crystal resonator electrode preparation and frequency trimming process, the process advantage can make up the process shortcoming of vacuum evaporation coating technology in the quartz crystal resonator electrodes preparation.This paper presented the research scheme of double-target pulsed unbalanced magnetron sputtering technology to the 10MHz AT-cut quartz crystal resonator electrodes preparation and frequency trimming process, and designed the equal precision frequency acquisition circuit based on FPGA to monitor the resonant frequency of quartz crystal resonators in the process of frequency trimming process. The paper gave a brief introduction to the electrodes preparation and frequency trimming process technology about quartz crystal resonator, mainly explained the principle of magnetron sputtering coating process and the experimtnet scheme, analysed the relationships during magnetron sputtering process parameters and deposition rate of Ag electrodes thin film and crystal structure by comparison the relevant experimental data. The electrode size of 10MHz AT-cut quartz crystal resonator was determined by researching the experience parameters and theoretical analysis, on this basis, the frequency coarse tuning and frequency trimming experiments were performed, the samples of 10MHz AT-cut quartz crystal resonator was prepared,the frequency deviation was controled within the range of±10ppm, the precision frequency acquisition circuit for quartz crystal resonators frequency trimming process has fast response speed and high frequency measurement precision, the highest frequency deviation is only 2×10-6when the gate time is 0.01s. Overall results show that two-target pulsed unbalanced magnetron sputtering technology has good potential applications in the preparation of quartz crystal resonator electrodes and frequency trimming process, the experimental results achieved the desired goal.