Apparent and steady-state etch rates in thin film etching and under-etching of microstructures : 2: characterization

Van Barel, Gregory; du Bois, Bert; van Hoof, Rita; De Wachter, Jef; de Ceuninck, Ward; Witvrouw, Ann

doi:10.1088/0960-1317/20/5/055034

Title

Apparent and steady-state etch rates in thin film etching and under-etching of microstructures : 2: characterization

Author

Van Barel, Gregory

du Bois, Bert

van Hoof, Rita

De Wachter, Jef

de Ceuninck, Ward

Witvrouw, Ann

Abstract

The apparent and steady-state etch rates of PECVD SiO(2), HDP SiO(2) and PECVD Si(3)N(4) are measured both in a single thin film and a stacked film configuration. This is done for a HF:H(2)O/1:1, a HF(49 wt%): IPA/1:1 and a BHF solution. It is shown that etch rates vary with the used etch time, confirming the influence of both an incubation and a rinsing period on the average etch rate when performing typical ex situ etch rate experiments. Hence, this second part of a set of two papers provides the experimental evidence for part I where a general etch rate model was proposed. Furthermore this work shows that the etch rate varies whether it is determined on a single layer, in a stacked configuration or while under-etching a structural layer. This confirms the need of a straightforward characterization method for under-etching measurements at the sacrificial release stage of MEMS fabrication processes. Therefore, a new characterization method, using a suspended beam array and a surface profilometer, is proposed to determine the amount of under-etch after sacrificial release of surface micromachined devices.

Language

English

Source (journal)

Journal of micromechanics and microengineering. - Bristol

Publication

Bristol : 2010

ISSN

0960-1317

DOI

10.1088/0960-1317/20/5/055034

Volume/pages

20 (2010) , p. 1-6