Image Of The Week - 10/13/2006



The image shows a 1 micron thick metal (tantalum) membrane supported on a silicon support structure. The membrane is suspended over a rectangular window of 30x400 micro-meters.

Certain metal membranes can be used for hydrogen separation. Micro scale hydrogen separators find application in micro fuel processors that deliver pure hydrogen to micro fuel cells. Micro fuel cells are envisioned to replace Li Ion Batteries in portable electronic devices.

The membrane was fabricated by a multi-step process. (1) On a silicon wafer, thin films of silicon oxide, silicon nitride and Ta were sequentially deposited using plasma enhanced chemical vapor deposition (PECVD) and sputtering. (2) Then the silicon wafer was patterned and etched through from the back side using deep reactive ion etching (DRIE). A channel was also etched in silicon for gas (permeate/retentate) flow. To create the structure of channel and support beams, double masks of silicon oxide and photo resist were used. (3) Finally, the oxide and nitride were etched using reactive ion etching (RIE) leaving the freely suspended tantalum.

Very good definitions and descriptions of DRIE, RIE, PECVD and sputtering can be found in http://en.wikipedia.org/

Image provided by: Samrat Mukherjee, Miltiadis K. Hatalis and Mayuresh V. Kothare (mayuresh.kothare@Lehigh.EDU).

Copyright © 2006 Samrat Mukherjee, Miltiadis K. Hatalis, Mayuresh V. Kothare, and Lehigh University. This image and information may not be reproduced without the prior consent of this website administrator or the image author.