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

Jun-Lin Zhang,Xiu-Tao Yang,Sheng-Ao Lin,Guang-Gen Zeng,Wen-Wu Wang,Zheng-Xiang Zhong,Bing Li,Cheng Chen,Shuang Liao,Feng Tan

doi:10.3390/mi12080894

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.

Highlights

Introduction published maps and institutional affilQuartz crystal resonators (QCR), which have the advantages of a stable frequency, relatively large bandwidth and a high quality factor, are among the key frequency electronic components in the modern information industry and have been widely used in various pieces of communications and electronic equipment [1,2]
The relationship between the change in the quartz crystal resonator (QCR) frequency ∆f 2 and the change in the electrode thickness in the etched area can be defined by the following formula:
The minimum Q value was only equivalent to 21.4% of that of an unetched QCR

Summary

Experiment

The resonance frequency of QCR has the following relationship with the frequency constant Kf : n (1). The relationship between the change in the QCR frequency ∆f 2 and the change in the electrode thickness in the etched area can be defined by the following formula:. Where A3 is the area of the etched pattern, and ∆tm is the thickness change in etched area This equation was used to calculate the thickness of the electrode to be etched by the laser. 1200 gr/mm and a laser of 632 nm ∆f excitation t ρ A where A3 is the area of the etched pattern, and Δtm is the thickness change in etched area This equation was used to calculate the thickness of the electrode to be etched by the which the electrodes on both sides were etched into through-holes. The Raman data (HORIBA Xplora plus) of etched silica were collected 5with a grating of 1200 gr/mm and a laser of 632 nm excitation under ambient conditions

Result and Discussion

Morphology Analysis

Raman Spectra

Findings

Conclusions