Micro-pressure sensors made of indium tin oxide thin films》.pdfVIP

Sensors and Actuators A 137 (2007) 1–5 Micro-pressure sensors made of indium tin oxide thin films Kai Wah Yeung, Chung Wo Ong ∗ Department of Applied Physics and Materials Research Center, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, People’s Republic of China Received 26 July 2006; received in revised form 2 January 2007; accepted 19 January 2007 Available online 30 January 2007 Abstract The microstructure, electrical resistivity and piezoresistive property of magnetron sputtered indium tin oxide (ITO) films were investigated as functions of preparation and post-annealing conditions. Annealing at 400 ◦C for 30 min resulted in low electrical resistivity ≤6.0 × 10−3 cm and observable piezoresistive coefficient ranging from −4.3 × 10−11 to −7.1 × 10−11 Pa−1. Prototypes of pressure sensors with an annealed ITO film deposited on a 25 m thick silicon diaphragm were fabricated. With a bias voltage of 1 V, the device gave a voltage response of 12.6 mV when the 4 4 differential pressure across the diaphragm varied from −6 × 10 to 6 × 10 Pa. © 2007 Elsevier B.V. All rights reserved. Keywords: Indium tin oxide; Magnetron sputtering; Piezoresistive property; Pressure sensors 1. Introduction ment. To date, many studies have been carried out to reveal the piezoresistive property [3–7] and electrical resistivity of ITO One conventional type of micro-pressure sensor is designed