Media protected surface micromachined leverage beam pressure sensor

In this paper we present the first surface micromachined ultraminiaturized, highly sensitive, pressure sensor that utilizes a force-transducing beam and a 2??m thick polysilicon pressure sensing diaphragm as an encapsulation layer for high media isolation of the sensing piezoresistor. A beam is attached to the diaphragm at one end and to the cavity at the other end. The pressure-induced diaphragm deflection is transduced to strain in the beam and sensed by a piezoresistive strain-gauge on the beam. The piezoresistor is thus well isolated from the sensing environment. The pressure sensing performance was measured to 0.9??V?V-1?mmHg-1.

[1]  Jakob Janting,et al.  Reliability of industrial packaging for microsystems , 1998 .

[2]  W. Ko,et al.  Development of a miniature pressure transducer for biomedical applications , 1979, IEEE Transactions on Electron Devices.

[3]  Lennart Löfdahl,et al.  Small piezoresistive silicon microphones specially designed for the characterization of turbulent gas flows , 1994 .

[4]  R. Hooke,et al.  Approximate Analysis of the Large Deflection Elastic Behaviour of Clamped, Uniformly Loaded, Rectangular Plates: , 1969 .

[5]  K.D. Wise,et al.  Scaling limits in batch-fabricated silicon pressure sensors , 1987, IEEE Transactions on Electron Devices.

[6]  L. Tenerz,et al.  A fiberoptic silicon pressure microsensor for measurements in coronary arteries , 1991, TRANSDUCERS '91: 1991 International Conference on Solid-State Sensors and Actuators. Digest of Technical Papers.

[7]  L. Tenerz,et al.  The first surface micromachined pressure sensor for cardiovascular pressure measurements , 1998, Proceedings MEMS 98. IEEE. Eleventh Annual International Workshop on Micro Electro Mechanical Systems. An Investigation of Micro Structures, Sensors, Actuators, Machines and Systems (Cat. No.98CH36176.

[8]  A. Nakladal,et al.  Influences of humidity and moisture on the long-term stability of piezoresistive pressure sensors , 1995 .

[9]  Karsten Dyrbye,et al.  Protective coatings in harsh environments , 1996 .

[10]  Karsten Dyrbye,et al.  Packaging of physical sensors for aggressive media applications , 1996 .

[11]  Ira E. Baskett,et al.  A vertically integrated media-isolated absolute pressure sensor , 1998 .

[12]  Martin Hill,et al.  Development and characterisation of a surface micromachined FET pressure sensor on a CMOS process , 1999 .

[13]  Darko Belavic,et al.  Silicon pressure sensors with a thick film periphery , 1998 .

[14]  L. E. Gates,et al.  Hermetic passivation of chip-on-board circuits , 1991, 1991 Proceedings 41st Electronic Components & Technology Conference.

[15]  Khalil Najafi,et al.  An ultraminiature CMOS pressure sensor for a multiplexed cardiovascular catheter , 1992 .

[16]  Andreas Schroth,et al.  Ambient humidity and moisture - a decisive failure source in piezoresistive sensors , 1995 .