A vertical micromachined resistive heater for a micro-gas separation column

摘要

This paper presents a micromachined vertical resistive heater fabricated as part of a micro-gas separation column. The complete device is formed from two silicon die electrostatically bonded to a single glass die. The glass die is conventionally machined and contains four through holes. The holes are filled with a zeolite adsorbent and thus act as separation columns. Each silicon die serves as a screen which allows air to flow through the device while holding the zeolite in place. The 5000 urn diameter screens are deep reactive ion-etched (DRIE) and contain 1964 square 50 μm × 50 μm × 350 μm channels. A junction isolated vertical resistor is integrated into one of the silicon die by performing a phosphorus diffusion after DRIE. Thus. the resistor is embedded into the walls of the micromachined silicon screen. The vertical resistor is used to heat a purge gas and regenerate the zeolite adsorbent. The measured vertical resistance is between 6 and 7 Ω. The residence time of the gas in the heater is ～60 ms assuming a 1 sccm N{sub}2 gas flow rate. The theoretical heat transfer coefficient is 3000 W/m{sup}2/℃. The power consumed to heat both the screen and the gas at steady state is ～33 mW per die.