Investigation of Surface Morphology Evolution During the Borosilicate Glass Etching by Using ICP-RIE For Microfluidic Applications

Dry etching techniques are extensively used in the fabrication of silicon-based electronic components; however, the increasing use of glass substrates in microfluidic applications, due to their chemical stability, biocompatibility, optical transparency, electrical insulation, and cost-effectiveness, has created a growing demand for efficient dry etching of glass. This work presents the etching of borosilicate glasses using inductively coupled plasma reactive ion etching (ICP-RIE) with fluorine-based gas chemistries for use in microfluidic applications. Microfluidic structures were patterned via photolithography technic with micropillar were patterned using a titanium/gold stack and a nickel hard mask. The effects of various gas mixtures on the etch rate and surface morphology were systematically investigated. Optical emission spectroscopy (OES) was employed to monitor plasma characteristics, while surface analyses and etch depth were carried out using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and profilometry, respectively. The results highlight how different gas compositions influence etch behavior and surface morphology, offering valuable insight for optimizing dry etching processes in glass-based microfluidic device fabrication and emphasize the importance of selecting appropriate gas ratios to achieve uniform microstructures with minimal surface defects.