Research on Trimming Frequency-Increasing Technology for Quartz Crystal Resonator Using Laser Etching

Abstract

A quartz crystal resonator (QCR) is an indispensable electronic component in the field of the modern electronics industry. By designing and depositing electrodes of different shapes and thicknesses on a quartz wafer with a certain fundamental frequency, the desired target frequency can be obtained. Affected by factors such as the deposition equipment, mask, wafer size and placement position, it is difficult to accurately obtain the target frequency at a given time, especially for mass-produced QCRs. In this work, a laser with a wavelength of 532 nm was used to thin the electrodes of a QCR with a fundamental frequency of 10 MHz. The electrode surface was etched through a preset processing pattern to form a processing method of local thinning of the electrode surface. At the same time, the effect of laser etching on silicon dioxide and resonator performance was analyzed. Satisfactory trimming frequency-increasing results were achieved, such as a frequency modulation accuracy of 1 ppm, frequency distribution with good consistency and equivalent parameters with small changes, by the laser partial etching of the resonator electrode. However, when the surface electrode was etched into using through-holes, the attenuation amplitude of the equivalent parameter became larger, especially in terms of the quality factor (Q), which decreased from 63 K to 1 K, and some resonators which had a serious frequency drift of >40%. In this case, a certain number of QCRs were no longer excited to vibrate, which was due to the disappearance of the piezoelectric effect caused by the local thermal phase change in the quartz wafer.

Design and Optimization of Laser Processing Control System and Process Parameters for Micro Crystal Resonator Frequency Modulation

“…When the mass of the silver layer is increased, the resonant frequency of the MCR decreases. When the mass of the silver layer is reduced, the resonant frequency of the MCR increases [4]. The laser processing system for MCR frequency modulation mainly includes the MCR carrier module, the frequency detection module and the laser processing module.…”

“…According to the difference between the actual frequency and the target frequency of the MCR, the frequency of the MCR is adjusted by the laser processing module. A laser with a wavelength of 532 nm is used to thin the electrodes of the MCR with a fundamental frequency of 10 MHz [4]. Laser irradiates the surface of the MCR to vaporize the silver layer.…”