An integrated thermopile structure with high responsivity using any standard CMOS process

This paper reports a new thermopile structure using n-poly/p/sup +/-active layers that are available in any CMOS technology. The thermopile structures are obtained by postetching of the fabricated and bonded chips. P/sup +/-active layers are placed in n-well regions, which are protected from etching by electrochemical etch-stop technique in a TMAH solution. The characterization results show that Seebeck coefficients of the n-poly and p/sup +/-active layers are -335 /spl mu/V/K and 450 /spl mu/V/K, respectively. Tests show that a cantilever type thermopile with 21 thermocouples will result in responsivity and detectivity of 43 V/W and 1.06/spl times/10/sup 7/ (cm./spl radic/Hz)/W, respectively, when n-well is present and 617 V/W and 1.5/spl times/108 (cm./spl radic/Hz)/W, respectively, when n-well is removed.

[1]  O. Paul,et al.  Test structures to measure the Seebeck coefficient of CMOS IC polysilicon , 1996, Proceedings of International Conference on Microelectronic Test Structures.

[2]  Osamu Tabata,et al.  pH-controlled TMAH Etchants For Silicon Micromachining , 1995, Proceedings of the International Solid-State Sensors and Actuators Conference - TRANSDUCERS '95.

[3]  K. Baert,et al.  Thin Film Boron Doped Polycrystalline Silicon/sub70%/-germanium/sub30%/ For Thermopiles , 1995, Proceedings of the International Solid-State Sensors and Actuators Conference - TRANSDUCERS '95.

[4]  G. Kittilsland,et al.  Boron Etch-stop In TMAH Solutions , 1995, Proceedings of the International Solid-State Sensors and Actuators Conference - TRANSDUCERS '95.

[5]  W. Budde,et al.  A Thermoelectric Infrared Radiation Sensor With Monolithically Integrated Amplifier Stage And Temperature Sensor , 1995, Proceedings of the International Solid-State Sensors and Actuators Conference - TRANSDUCERS '95.

[6]  Kensall D. Wise,et al.  A Bulk-micromachined 1024-element Uncooled Infrared Imager , 1995, Proceedings of the International Solid-State Sensors and Actuators Conference - TRANSDUCERS '95.

[7]  H. Baltes,et al.  Process-dependent Thermophysical Properties Of CMOS IC Thin Films , 1995, Proceedings of the International Solid-State Sensors and Actuators Conference - TRANSDUCERS '95.

[8]  M. Schmidt,et al.  An Etch-stop Utilizing Selective Etching Of N-type Silicon By Pulsed Potential Anodization , 1992 .

[9]  U. Schnakenberg,et al.  TMAHW etchants for silicon micromachining , 1991, TRANSDUCERS '91: 1991 International Conference on Solid-State Sensors and Actuators. Digest of Technical Papers.

[10]  Pasqualina M. Sarro,et al.  Integrated thermopile sensors , 1990 .

[11]  A. M. Robinson,et al.  A new approach for the fabrication of micromechanical structures , 1989 .

[12]  S. D. Collins,et al.  Study of electrochemical etch-stop for high-precision thickness control of silicon membranes , 1989 .

[13]  A. Reisman,et al.  The Controlled Etching of Silicon in Catalyzed Ethylenediamine‐Pyrocatechol‐Water Solutions , 1979 .

[14]  G. Kovacs,et al.  Micromachined thermally isolated circuits , 1997 .

[15]  R. Lenggenhager,et al.  CMOS thermoelectric infrared sensors , 1994 .