MEMS technology is used in ultra-small tuning fork crystals, reducing the volume to 1/10 of the original product。
    The tuning fork resonator includes a bottom and two vibrating arms extending from the bottom. Excitation electrodes (red part) are plated on the two vibrating arms. After the wafer with the conventional structure is miniaturized, the area of the excitation electrode will be reduced, which is not conducive to vibration. MEMS technology uses three-dimensional processing of the vibrating plate to form an H-shaped groove structure, which not only ensures the area of the electrode, but also improves the efficiency of electrolysis. MEMS technology has effectively promoted the miniaturization of crystal resonators. The volume of crystal oscillators processed by photolithography has been reduced to 18.8mm3 small tuning fork crystal devices, which are only less than 1/10 of the original product。
    MEMS technology is used for AT-type crystal/AT oscillator, keeping the dimensional tolerance within 1um.
    The photolithography processing using MEMS technology can improve the consistency and stability of the quartz crystal chip, and the photoetching process can keep the dimensional tolerance within 1um.
    The photolithography process first uses an electron beam vacuum deposition system to chemically etch the quartz wafer to a predetermined frequency, clean it and metallize it with a thin film of chromium and gold. Quartz mask and dual aligner lithography generate AT stripe patterns in which the top and bottom surfaces of the wafer are aligned and exposed at the same time. The crystal electrode and probe pad case are then defined by the subsequent photomasking step. The wafer is then chemically metal and quartz etched to form individual AT strips. Finally, a hole mask and thin film metal deposition are used to connect the top and bottom mounting pads together. After the photolithography process is completed, the wafer contains hundreds of independent ultra-small AT crystal resonators.