Title :
Tin oxide gas sensor fabricated using CMOS micro-hotplates and in-situ processing
Author :
Suehle, John S. ; Cavicchi, Richard E. ; Gaitan, Michael ; Semancik, Steve
Author_Institution :
Nat. Inst. of Stand. & Technol., Gaithersburg, MD, USA
fDate :
3/1/1993 12:00:00 AM
Abstract :
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.<>
Keywords :
CMOS integrated circuits; electric sensing devices; gas sensors; integrated circuit technology; semiconductor materials; semiconductor thin films; sputter deposition; sputtered coatings; tin compounds; 350 degC; CMOS micro-hotplates; H/sub 2/; MOSIS; O/sub 2/; SnO/sub 2/; SnO/sub 2/-Si; commercial CMOS foundry fabrication; film growth; film resistivity; gas sensor; in-situ processing; low-cost CMOS-based gas sensor system; monitoring; monolithic sensor; postfabrication processing techniques; process control; sensing film; sputter-deposited; temperature control; CMOS process; Fabrication; Foundries; Gas detectors; Semiconductor films; Sensor arrays; Silicon; Temperature control; Temperature sensors; Tin;
Journal_Title :
Electron Device Letters, IEEE
