Thick and Thermally Isolated Si Microheaters for Microfabricated Preconcentrators
Journal
Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures
Journal Volume
21
Journal Issue
1
Pages
274-279
Date Issued
2003-01
Author(s)
WEI-CHENG TIAN
S. W. Pang
Abstract
Thick thermally isolated microheaters in Si are fabricated using high aspect ratio etching technology. These thick microheaters a with large surface area provide the large adsorbent capacity needed for high sensitivity microfabricated preconcentrators in a microgas chromatography system. In addition, air gaps around the microheaters provide good thermal isolation to lower the power consumption. A 520 μm thick Si microheater with good thermal isolation has been made and its back side is anodically bonded to a pyrex glass substrate. To provide good thermal isolation, a 500 μm wide air gap around the microheater, thin poly-Si interconnects on top of dielectric membrane, and air gap isolation from the bottom glass substrate are used. Microheaters with a 500 μm air gap can be heated up 50% faster to a temperature of 270 °C compared to those with a 100 μm air gap, while the power consumption is 25% less and there is a larger temperature difference between the microheater and the bonding area. Operating the microheater in a vacuum results in lower power consumption. At 250 °C, 35% less power is needed at 1.2 Torr compared to atmospheric pressure. The power consumption is further reduced by minimizing the contact area with the heater support substrate. Up to 34% power reduction has been demonstrated by placing heaters on a thin membrane or etching trenches in the supporting substrate. These thick thermally isolated Si microheaters can provide good power efficiency, large adsorbent capacity, and high mechanical strength for microfabricated preconcentrators.
SDGs
Type
journal article