Design of low-temperature CMOS-process compatible membrane fabricated with sacrificial aluminum layer for thermally isolated applications

Kow-Ming Chang*, Ren Jie Lin, I. Chung Deng

*Corresponding author for this work

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

In the surface micromachining technique, residual stress and sticking effect play an important role in determining whether a microstructure is suspended or collapse during a release process. In this paper, we propose a simpler method for making suspended membranes for thermally isolated application by using cheap processing steps and compatible with CMOS-process; also, there are some simulations done to predict stiction as function of the anchor profile. It is demonstrated by fabricating the test structures of CMOS-process compatible surface micromachined bolometer using aluminum sacrificial layer with high yield and high throughput. The aluminum sacrificial layer provides some benefits including rapid wet-etching and high wet-etching selectivity with respect to dielectric materials. The residual stress and gravity of the microstructures are evaluated with structural simulations, and the sticking effect can be alleviated by an appropriate structure design and a release process. Once the residual stress is known, we can successfully use Coventorware simulations to predict a suspended membrane by controlling the anchor profile which contains sidewall conformal factor and sidewall angle. The simulation results are in good agreement with the experiments.

Original languageEnglish
Pages (from-to)660-667
Number of pages8
JournalSensors and Actuators, A: Physical
Volume134
Issue number2
DOIs
StatePublished - 15 Mar 2007

Keywords

  • Anchor profile
  • Residual stress
  • Sacrificial layer
  • Sticking effect
  • Surface micromachining

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