Highly Sensitive Dust Particle Detector using a Silicon Cantilever Microelectro-Mechanical System

Abstract

Dust particles have been recognized as one of the main contaminants in the microelectronic fabrication process, not to mention there harmful effects on every day human life. The conventional dust sensors detect only the mass-concentration per unit area, while it is important to distinguish the size distribution(mass distribution) and the time dependent quantity. Silicon based high sensitive cantilever(paddle : 1 mm X 1 mm, spring : 700 ?m X 100 ?m; thickness 8.6 ?m) sensors have been fabricated by standard micro electro mechanical system (MEMS) for monitoring the amount and size distribution of dust particles in the atmosphere. Dust particles were attached at the electrode surface formed on the paddle of the cantilever using electrostatic interaction. The cantilever resonance frequency(2.615 kHz) changed by the deflection caused when the dust particles were attached to the paddle of the cantilever and it was possible to detect a single event by monitoring the phase shift. We found that increasing the applied voltage resulted in a steady increase in phase shift, which was due to the small-sized uniform dust particles (r<1 ?m) landing, while a sudden change of phase was observed for particles with increased mass. The removal of dust particles depends on many factors, the applied voltage, surface properties, temperature, humidity, and other particle attachment, etc. We will also present results on the investigation of the particle detaching characteristics of the silicon cantilever sensor with changing atmospheric conditions