Tin oxide gas sensor fabricated using CMOS micro-hotplates and in-situ processing

• Published in: IEEE electron device letters 1993-03, Vol.14 (3), p.118-120
• Main Authors: Suehle, J.S., Cavicchi, R.E., Gaitan, M., Semancik, S.
• Format: Article
• Language: English
• Subjects: CMOS process; Exact sciences and technology; Fabrication; Foundries; Gas detectors; General equipment and techniques; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Physics; Semiconductor films; Sensor arrays; Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing; Silicon; Temperature control; Temperature sensors; Tin
• ISSN: 0741-3106; 1558-0563
• DOI: 10.1109/55.215130

A monolithic tin oxide (SnO/sub 2/) gas sensor realized by commercial CMOS foundry fabrication (MOSIS) and postfabrication processing techniques is reported. The device is composed of a sensing film that is sputter-deposited on a silicon micromachined hotplate. The fabrication technique requires no masking and utilizes in situ process control and monitoring of film resistivity during film growth. Microhotplate temperature is controlled from ambient to 500 degrees C with a thermal efficiency of 8 degrees C/mW and thermal response time of 0.6 ms. Gas sensor responses of pure SnO/sub 2/ films to H/sub 2/ and O/sub 2/ with an operating temperature of 350 degrees C are reported. The fabrication methodology allows integration of an array of gas sensors of various films with separate temperature control for each element in the array, and circuits for a low-cost CMOS-based gas sensor system.< >