Jump to main content
Jump to site search

Issue 4, 2010
Previous Article Next Article

Wet-etching of structures with straight facets and adjustable taper into glass substrates

Author affiliations

Abstract

Wet etching of glass by hydrofluoric acid is widely used in microfabrication, but is limited by the isotropic nature of the process that leads to rounded sidewalls and a 90° angle between the etch front and the surface of the substrate. For many applications such as microvalving, or for further processing such as spin-coating, well controlled, gently sloping sidewalls are often preferred. Here, we present a new approach for forming straight facets and for adjusting the sidewall angle in wet-etched glass substrates by controlling the lateral dissolution of an etch mask during etching. The etch mask comprises a Ti–Au bilayer where Au serves to protect the Ti. During isotropic etching of glass by HF the Ti layer is etched away laterally at the same time, which leads to straight, gently sloping sidewalls. We introduce two methods for controlling the sidewall angle. The first one is based on adjusting the thickness of Ti which controls the lateral etch rate, and thus the angle; the thinner the Ti, the slower its lateral etch rate and the steeper the angle in the etched glass. The second method involves a cathodic bias applied to the Ti–Au etch mask which again regulates the dissolution rate of Ti; the more negative the bias the slower the lateral etch rate. Both methods offer accurate control of the sidewall angle over a wide range, can be readily integrated into existing fabrication processes, and will be particularly useful for making channels with trapezoidal cross-sections, valve seats with gentle profiles, or for patterning electrodes across and inside of microfluidic channels.

Graphical abstract: Wet-etching of structures with straight facets and adjustable taper into glass substrates

Back to tab navigation

Supplementary files

Publication details

The article was received on 29 Jun 2009, accepted on 08 Oct 2009 and first published on 01 Dec 2009


Article type: Paper
DOI: 10.1039/B912770D
Lab Chip, 2010,10, 494-498

  •   Request permissions

    Wet-etching of structures with straight facets and adjustable taper into glass substrates

    N. Pekas, Q. Zhang, M. Nannini and D. Juncker, Lab Chip, 2010, 10, 494
    DOI: 10.1039/B912770D

Search articles by author

Spotlight

Advertisements