By Topic

Elimination of stress-induced curvature in thin-film structures

Sign In

Cookies must be enabled to login.After enabling cookies , please use refresh or reload or ctrl+f5 on the browser for the login options.

Formats Non-Member Member
$31 $13
Learn how you can qualify for the best price for this item!
Become an IEEE Member or Subscribe to
IEEE Xplore for exclusive pricing!
close button

puzzle piece

IEEE membership options for an individual and IEEE Xplore subscriptions for an organization offer the most affordable access to essential journal articles, conference papers, standards, eBooks, and eLearning courses.

Learn more about:

IEEE membership

IEEE Xplore subscriptions

4 Author(s)
Bifano, T.G. ; Manuf. Eng. Dept., Boston Univ., Brookline, MA, USA ; Johnson, H.T. ; Bierden, P. ; Mali, R.K.

Argon ion machining of released thin-film devices is shown to alter the contour shape of free-standing thin-film structures by affecting their through-thickness stress distributions. In experiments conducted on MEMS thin-film mirrors it is demonstrated that post-release out-of-plane deformation of such structures can be reduced using this ion beam machining method. In doing so optically flat surfaces (curvature <0.001 mm-1) are achieved on a number of 3 μm-thick surface micromachined silicon structures, including mirrors with either initially positive curvature or initially negative curvature measuring up to 0.02 mm-1. An analytical model incorporating the relevant mechanics of the problem is formulated and used to provide an understanding of the mechanisms behind the planarization process based on ion machining. The principal mechanisms identified are 1) amorphization of a thin surface layer due to ion beam exposure and 2) gradual removal of stressed material by continued exposure to the ion beam. Curvature history predictions based on these mechanisms compare well with experimental observations.

Published in:

Microelectromechanical Systems, Journal of  (Volume:11 ,  Issue: 5 )