Profile Control of a Borosilicate-Glass Groove Formed by Deep Reactive Ion Etching

TL;DR

This paper presents methods to improve the sidewall angle of borosilicate glass grooves etched by DRIE, using polymer removal techniques to achieve angles up to 85 degrees for better profile control.

Contribution

It introduces a novel combined process of DRIE and ultrasonic cleaning to effectively remove polymer films and enhance groove profile control.

Findings

Both methods improved sidewall angle to 85 degrees.

Ultrasonic cleaning combined with DRIE effectively removes polymer films.

Process is independent of mask-opening width.

Abstract

Deep reactive ion etching (DRIE) of borosilicate glass and profile control of an etched groove are reported. DRIE was carried out using an anodically bonded silicon wafer as an etching mask. We controlled the groove profile, namely improving its sidewall angle, by removing excessively thick polymer film produced by carbonfluoride etching gases during DRIE. Two fabrication processes were experimentally compared for effective removal of the film : DRIE with the addition of argon to the etching gases and a novel combined process in which DRIE and subsequent ultrasonic cleaning in DI water were alternately carried out. Both processes improved the sidewall angle, and it reached 85o independent of the mask-opening width. The results showed the processes can remove excessive polymer film on sidewalls. Accordingly, the processes are an effective way to control the groove profile of borosilicate glass.