Deep NLD plasma etching of Fused Silica and Borosilicate Glass

In this paper, we report development of deep plasma etching process for Fused Silica (FS) and Borosilicate Glass (BSG) using magnetic Neutral Loop Discharge (NLD) plasma, achieving a depth of 100 μm, a high aspect ratio of 8:1, nearly vertical walls, and etch rate as high as 0.75 μm/min. The plasma conditions, such as gas flow, power, pressure, and masking materials were experimentally analyzed and optimized for improved aspect ratio, selectivity, sidewall angle, etch rate, and etch quality. The design of experiment with etching parameters and variation in masking materials provides a systematic approach to the fabrication of sensors, resonators and microsystems using FS and BSG.