This work presents film properties and initial reliability studies for thin Teflon-like films applied to a unique test vehicle, the Sandia-designed and fabricated microengine. Results on microengines coated with the film show a factor of three improvement in their lifetime and an order of magnitude reduction in the coefficient of friction when compared to uncoated samples. Coefficients Of Friction (COF) of 0.07 for the Teflon-like film and 1.0 for uncoated samples are extracted from models which match the measured behavior of working microengines. These films, deposited from a plasma source, exhibit the ability to penetrate into very narrow, deep channels common to many MEMS devices. For as-deposited film, both the refractive index at 1.4 and the contact angle with water at 108 degrees show the film to be very similar to bulk Teflon PTFE. Film stability as a function of temperature has been examined using Fourier Transform Infrared (FTIR) spectroscopy. The film structure as observed by the fluorine- carbon (F-C) peak is stable up to 200 C, but starts decomposing above 250 C. Film composition has been examined using X-ray photoelectron spectroscopy (XPS) and is quite different for directly exposed surfaces compared with deep, narrow channels where the deposition process is diffusion limited.

Date Published: 31 August 1998
PDF: 11 pages
Proc. SPIE 3511, Micromachining and Microfabrication Process Technology IV, (31 August 1998); doi: 10.1117/12.324289

Published in SPIE Proceedings Vol. 3511:
Micromachining and Microfabrication Process Technology IV
James H. Smith, Editor(s)