| dc.description.abstract | Quartz crystals possess superior chemical stability compared to ceramics and nickel-chromium alloys, making them widely used in instruments and equipment in industries such as semiconductors and optomechanics. Since the discovery of the piezoelectric effect by the Curie brothers in 1880, numerous naturally occurring or artificially synthesized piezoelectric materials have been gradually unearthed. In the mid-20th century, oscillators using α-quartz single-crystal quartz as a carrier began to be extensively used in electronic network systems as the core for generating clock signals. AT-cut quartz crystals exhibit excellent frequency
stability and are widely utilized in passive and active components.
In the 21st century, from 4G and 5G information networks to industrial electromechanical systems and even space satellites, all encompassed in the communication
infrastructure, the demand for manufacturing over 20 billion electronic components annually has grown. Therefore, there is a higher requirement for the stability of digital signals. In addition, to meet commercial needs, the semiconductor industry and related sectors have been pursuing more precise dimensions, lower costs, and faster speeds over the past few decades, which necessitates the development of new technologies or the continuous
improvement of existing mature processes. The rapid drilling of micrometer-sized holes on thin quartz wafers for wiring, metal electrode deposition, internal oscillator wafer
connections, and improved crystal stability is a highly promising research area.
The hardness and brittleness of quartz crystals, as well as their high penetration
characteristics, have posed significant challenges in the field of precision machining.
Ultrashort pulsed lasers, due to their low thermal impact, high processing speed, and low
material consumption rate, are considered one of the promising methods for machining
quartz. In this study, a femtosecond laser galvanometer system with wavelengths of 1030 nm and 515 nm was used to investigate the influence of laser beam properties and scanning strategies on drilling holes in 80 μm thick quartz wafers. The experiment was combined with post-processing using a 35 wt.% potassium hydroxide (KOH) etching solution to remove the residual recast layer after laser processing.
The experimental results confirmed that the 515 nm S-polarized green laser, compared to the 1030 nm P-polarized infrared laser, can precisely remove or modify the material inside the holes. Micro-drilling with diameters of 70 μm and 50 μm was successfully completed within 3.6 s and 2.5 s, respectively. Transmission electron microscopy (TEM) analysis also indicated excellent performance of KOH etching, as no polycrystalline or amorphous regions were observed inside the holes. This achieved high-quality through-holes with a taper angle of less than 1°, and with parameter optimization, the process can be expected to be
comparable to advanced techniques such as trepanning optics system and Bessel beam, thereby reducing production costs. | en_US |