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 5000μm diameter screens are Deep Reactive Ion Etched (DRIB) and contain 1964 square 50μm×50μm×350μm channels. A vertical resistor is also integrated onto one of the silicon die. The junction isolated resistor is formed from a phosphorus diffusion which occurs 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 6Ω and 7Ω. The residence time of the gas in the heater is ～60msec assuming a ISCCM N2 gas flow rate. The theoretical heat transfer coefficient is 3000W/m{sup}2/°C. The power consumed to heat both the screen and the gas at steady state is ～33mW/die.