Analysis of material properties for MEMS using interferometric measurements

Conor O'Mahony; Martin Hill; Alan Mathewson

doi:10.1117/12.463655

27 August 2003 Analysis of material properties for MEMS using interferometric measurements

Conor O'Mahony, Martin Hill, Alan Mathewson

Proceedings Volume 4876, Opto-Ireland 2002: Optics and Photonics Technologies and Applications; (2003) https://doi.org/10.1117/12.463655
Event: OPTO Ireland, 2002, Galway, Ireland

Abstract

As the scope and depth of research into microelectromechanical systems increases, the issue of mechanical characterisation has emerged as a major consideration in device design. It is now common to include a set of test structures on a MEMS wafer for extraction of thin film material properties (in particular, residual stress and Young's modulus). These structures usually consist of micromachined beams and strain gauges, and measurement techniques include tensile testing, electromechanical characterisation, SEM imaging, and Raman spectroscopy. However, some of these tests are destructive and difficult to carry out at wafer scale. This work uses electrostatic actuation to pull fixed-fixed beams towards the substrate, and a white-light interferometer to record the beam deflection profile. Finite-element simulation software is employed to model this deflection, and to estimate the material properties which minimise the difference between the measured and simulated profiles. The test is non-destructive, suitable for wafer-level characterisation, and the structures involved require less die space than other methods. We have developed a 1.5mm surface micromachining process for the fabrication of composite and monolayer structures with applications in relay switching, optical imaging and radio-frequency components. This work presents results obtained using interferometric analysis for both monolayer (titanium) and composite (SiOx - metal) thin films fabricated with this process.

Citation Download Citation

Conor O'Mahony, Martin Hill, and Alan Mathewson "Analysis of material properties for MEMS using interferometric measurements", Proc. SPIE 4876, Opto-Ireland 2002: Optics and Photonics Technologies and Applications, (27 August 2003); https://doi.org/10.1117/12.463655

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available