WO2000075649A1 - Low-power sensor - Google Patents
Low-power sensor Download PDFInfo
- Publication number
- WO2000075649A1 WO2000075649A1 PCT/SE2000/001134 SE0001134W WO0075649A1 WO 2000075649 A1 WO2000075649 A1 WO 2000075649A1 SE 0001134 W SE0001134 W SE 0001134W WO 0075649 A1 WO0075649 A1 WO 0075649A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- island
- micro
- silicon
- hotplate
- several
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/414—Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS
- G01N27/4141—Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS specially adapted for gases
Definitions
- Gas-sensitive field-effect (GasFETs) devices have been studied for about 25 years.
- the replacement of the MOSFET gate by materials having catalytic properties (Pt, Pd, Ir7) allows the detection of several gases.
- they have shown to be suitable for different applications such as hydrogen monitor and leak detectors and electronic noses.
- Portable instruments and automotive industry are markets where low-cost and low-power consumption devices are in constant development.
- MOSFET type gas sensors are when used usually heated to a temperature over 100 °C to increase sensitivity and are limited to 175-200°C due to the use of standard silicon fabrication technologies.
- the present power consumption for one sensor is about 0.5 to 1.0 W, a major part of which is used to heat the sensor to its working temeperature.
- a low-power consumption array of GasFETs has been developed to make this technology competitive with the others on these markets.
- GasFETs gas-sensitive field-effect
- the object of the invention is solved by means of a design and fabrication methodology for micro-machined semiconductor devices comprising "hotplate devices", which makes it possible to combine micro-machining processing with the integration on the hotplate of active microelectronic chemical sensors exposed to the ambient.
- the device includes a support substrate, a membrane extending over a well in the substrate, and a semiconductor island attached to the membrane and isolated thermally, from the support substrate.
- the semiconductor island serves as a substrate for the integration of microelectronic chemical sensors, which are exposed to the ambient for instance through a hole in the membrane.
- the device may include also other active microelectronic components, e.g., circuits for control and sensing, which may be protected by the membrane if required.
- a micro-hotplate chemical sensor device By including an electric heater and a temperature sensor in the island, a micro-hotplate chemical sensor device is obtained that can be heated under temperature control using very low power.
- the most important advantage of the disclosed device as compared to traditional devices is that any active microelectronic chemical sensor can be integrated in the hotplate, while still being exposed to the ambient gas or liquid surrounding the device.
- chemical sensors based on the so-called field- effect detection mechanism.
- Field-effect gas sensors have proven to be very useful in many applications, either as single sensors, as arrays consisting of several sensors, or in combination with one or several sensors that utilize a different detection mechanism.
- By utilizing the disclosed device it becomes possible to make low-power field-effect gas sensors and sensor arrays.
- the operating temperature of the field-effect gas sensors can be pulsed or varied swiftly in some other way and sensors integrated in the same micro hotplate can be operated at different temperatures.
- Arrays of multiple sensors can be integrated on the disclosed micro-hotplate together with individual circuits for control and sensing, allowing an independent operation of each individual sensor. Also heating to operating temperatures can be very quick, almost instantaneous.
- the resulting devices are, e.g., suitable for applications in automobiles, portable gas-sensor instruments, and for on-line measurements using distributed sensor systems.
- FIG. 1 depicting a cross section of an embodiment of the invention
- the cross section is very much enlarged and not to scale since the dimensions in the vertical direction (as viewed) is enlarged many times more than the horizontal direction for improved illustration.
- Fig 2 shows a similar device somewhat simplified and fabricated in accordance with claim 13.
- Fig 3 illustrates yet another way to fabricate a micro-hotplate, this time in accordance with claim 15.
- fig 4 a micro-hotplate made in accordance with claim 16 is shown.
- Fig. 5 is a cross section of a device similar to fig 1 , but where the sensor is contactable by for instance ambient gas in a more direct manner.
- the MOSFETs array gas sensor realized (fig. 1) has been designed in the aim of reducing the source and drain leakage currents and the power consumption of this type of gas sensors.
- Each device consists of 4 GasFETs, a temperature sensor (diode) and a heater.
- the actual chip size is
- the heater is a semiconducting resistor, which is made during the p-well implantation of the MOSFET fabrication process.
- the transistors (NMOS) and the diode temperature sensor are made in a single diffusion step of doping atoms from CVD oxide films.
- Arrays with 4 medium or small MOSFETs have been designed respectively with a channel length of 13.0 and 5.0 ⁇ m.
- the fabrication of NMOS transistors in a p-well technology allows to drive them separately.
- Their source/drain leakage currents have been limited by minimizing the p-n junction surface at the source and the drain regions. Therefor, the metal / semiconductor contacts are directly taken on the source and the drain just beside the gate.
- GasFETs operate with their drain and gate connected together with a constant current bias between the source and the drain. In this design, the drain and gate were not connected together to allow more flexibility during the characterization of the
- MOSFETs electrical properties.
- the thermal mass and therefore the power consumption of the sensor are minimized by the design.
- the GasFETs, the heater and the diode are located in a silicon island isolated from the chip frame by a dielectric membrane.
- the membrane is made of LPCND low-stress silicon nitride.
- a PECND silicon nitride film is used as a passivation layer on the aluminum
- the membrane size is 1.8 x 1.8 mm and the silicon island area is 900 x 900 ⁇ m and 10 ⁇ thick.
- the process starts with the implantation of boron in a 4" silicon substrate (25 ⁇ cm, n type, 300 ⁇ m thick double face polished) to form the MOSFETs p-well, the p side of the diode and the resistive heater. Also included in this first part is the deposition and patterning of boron and phosphorus doped CND oxide films and the diffusion of the doping atoms to form the n+ and p+ regions of the electronic devices.
- the second part starts with the growth of a thermally gate oxide (100 nm) followed by the deposition of a low-stress silicon rich nitride LCPND film. Then, the gate and contacts are defined in the nitride.
- the metallization is deposited by e-beam evaporation of aluminum, which is annealed to form ohmic contacts on silicon.
- a PECND reactor is used to deposit a silicon nitride passivation layer on the device. After the patterning of the passivation film, thin catalytic metals (CM : Pt, Ir, Pd) are deposited, patterned and annealed.
- GasFETs with 4 different catalytic metals can be fabricated or one of them can be coated by aluminum and used as a reference. Since the deposition of the CM layers is done prior to the bulk silicon micromachining, a chuck is used in the third and last part of the processing to protect the front side of the wafer during the back side etching of silicon in KOH.
- the silicon island is defined and protected by the thermally grown oxide film during the etching of 10 ⁇ m of silicon in standard KOH (40% at 60°C) to define the silicon island thickness.
- the silicon is entirely etched by using 52% KOH (solubility limit of KOH in water at room temperature) at 70°C.
- KOH with a concentration of 52% is used to decrease the etch rate of the (311) planes, forming the side of the silicon island, compared to the etch rate of the (100) plane, which is the plane forming the bottom of the silicon island.
- KOH solubility limit of KOH in water at room temperature
- ⁇ 100> to the wafer surface is about 1.4 for this specific KOH solution.
- the release of membrane has to be done with a precise time control of the silicon etching rate to obtain the desired silicon island thickness.
- Double-face polished wafers with a TTN (Total Thickness Variance) as low as possible are needed since the uniformity of the silicon islands thickness on the entire wafer depends on this parameter.
- the whole fabrication process includes 50 steps, 15 of which are photolithographies (12 masks).
- the fabrication process is compatible with the use of different gate insulators as silicon dioxide (SiO 2 ), silicon nitride (Si N ), aluminum oxide (Al 2 O 3 ) and tantalum oxide (Ta 2 O 5 ).
- MOSFETs designed for this low-power device have shown that they are suitable for gas sensing at temperature up to 225°C. At this maximum operating temperature, a constant current bias of at least 200 ⁇ A is needed between the source and drain (connected to the gate) to avoid the interference of leakage currents.
- Bulk devices coated with thin CM layers show a good sensitivity to H 2 and NH 3 at an operating temperature of l40°C (E/g. 4).
- the heater resistance value is 1175 ⁇ ⁇ 30% and decreases as a function of temperature with the behaviour expected for a semiconductor. Power consumption of the device has been evaluated by using the diode previously calibrated as a function of temperature. A low power consumption of 80 mW is achieved for an operating temperature of 175°C for the array of 4 GasFETs compared to 0.5-1.0 W for one standard GasFET
- the silicon island ensures a uniform temperature distribution all over the active area.
- the low thermal mass allows the operation of the sensor in a temperature cycling mode, which enhances the power consumption of the device and could influence the selectivity as in resistive gas sensors.
- the design, fabrication and characterization of a low-power consumption MOSFETs array gas sensor have been presented.
- the sensor consists of a heating resistor, a diode temperature sensor and 4 GasFETs located in a silicon island thermally isolated from the chip frame by a dielectric membrane.
- the combination of microelectronics and MEMS (silicon bulk micromachining) fabrication technologies was used to fabricate these devices.
- the array of 4 GasFETs has a low-power consumption of 80 mW at an operating temperature of 175°C.
- the silicon island also provides a uniform temperature all over the sensing area. The low thermal mass of the device allows the operation of the sensors in a temperature cycling mode.
- the membrane may comprise silicon without loss of thermal isolation.
- the silicon in the membrane may be thin, shaped as spokes or low-doped or even undoped or combinations thereof rendering the thermal losses through the silicon small.
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU54354/00A AU5435400A (en) | 1999-06-04 | 2000-05-31 | Low-power sensor |
EP00939231A EP1190242A1 (en) | 1999-06-04 | 2000-05-31 | Low-power sensor |
JP2001501874A JP2003501657A (en) | 1999-06-04 | 2000-05-31 | Low power consumption sensor |
NO20015916A NO20015916L (en) | 1999-06-04 | 2001-12-04 | Low current sensor |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SE9902081A SE524102C2 (en) | 1999-06-04 | 1999-06-04 | Micro-hotplate device with integrated gas-sensitive field effect sensor |
SE9902081-0 | 1999-06-04 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2000075649A1 true WO2000075649A1 (en) | 2000-12-14 |
Family
ID=20415910
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/SE2000/001134 WO2000075649A1 (en) | 1999-06-04 | 2000-05-31 | Low-power sensor |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP1190242A1 (en) |
JP (1) | JP2003501657A (en) |
AU (1) | AU5435400A (en) |
NO (1) | NO20015916L (en) |
SE (1) | SE524102C2 (en) |
WO (1) | WO2000075649A1 (en) |
Cited By (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6410445B1 (en) | 1999-01-25 | 2002-06-25 | Appliedsensor Sweden Ab | Manufacturing method for integrated sensor arrays |
WO2002090950A1 (en) * | 2001-05-04 | 2002-11-14 | The University Court Of The University Of Paisley | Optically energised & interrogated sensors |
US6569779B1 (en) | 1998-05-08 | 2003-05-27 | Nordic Sensor Technologies Ab | Device for gas sensing |
DE10219726A1 (en) * | 2002-05-02 | 2003-11-27 | Eads Deutschland Gmbh | Production of a bridge-like semiconductor gas sensor comprises preparing a SOI element, forming an electrode arrangement on an electrically insulating layer |
DE102004017750A1 (en) * | 2004-04-06 | 2005-10-27 | Flechsig, Gerd-Uwe, Dr. rer. nat. | Array of heatable electrodes and chemical and biochemical analysis |
EP1736768A1 (en) | 2005-06-22 | 2006-12-27 | Appliedsensor Sweden AB | Device and method for gas sensing |
WO2007009948A1 (en) * | 2005-07-15 | 2007-01-25 | Siemens Aktiengesellschaft | Method for the simultaneous detection of a plurality of different types of atmospheric pollution using gas-sensitive field effect transistors |
WO2013092823A1 (en) * | 2011-12-23 | 2013-06-27 | Sanofi-Aventis Deutschland Gmbh | Sensor arrangement for a packaging of a medicament |
WO2014012948A1 (en) | 2012-07-16 | 2014-01-23 | Sgx Sensortech Sa | Micro-hotplate device and sensor comprising such micro-hotplate device |
WO2017044267A1 (en) * | 2015-09-09 | 2017-03-16 | Invensense, Inc. | Gas sensor platform and the method of making the same |
US9716140B2 (en) | 2014-04-02 | 2017-07-25 | Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forschung E. V. | Fluid sensor and method for examining a fluid |
US10383967B2 (en) | 2016-11-30 | 2019-08-20 | Invensense, Inc. | Substance sensing with tracers |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20100176463A1 (en) * | 2007-07-19 | 2010-07-15 | Renesas Technology Corp. | Semiconductor device and manufacturing method of the same |
JP5507524B2 (en) * | 2011-11-07 | 2014-05-28 | 株式会社日立製作所 | Combustible gas sensor |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1994010821A1 (en) * | 1992-10-26 | 1994-05-11 | UNITED STATES OF AMERICA, as represented by THE UNITED STATES DEPARTMENT OF COMMERCE | Application of microsubstrates for materials processing |
WO1994010822A1 (en) * | 1992-10-26 | 1994-05-11 | THE UNITED STATES OF AMERICA as represented by THEUNITED STATES DEPARTMENT OF COMMERCE | Micro-hotplate devices and methods for their fabrication |
-
1999
- 1999-06-04 SE SE9902081A patent/SE524102C2/en not_active IP Right Cessation
-
2000
- 2000-05-31 EP EP00939231A patent/EP1190242A1/en not_active Withdrawn
- 2000-05-31 AU AU54354/00A patent/AU5435400A/en not_active Abandoned
- 2000-05-31 JP JP2001501874A patent/JP2003501657A/en not_active Withdrawn
- 2000-05-31 WO PCT/SE2000/001134 patent/WO2000075649A1/en not_active Application Discontinuation
-
2001
- 2001-12-04 NO NO20015916A patent/NO20015916L/en unknown
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1994010821A1 (en) * | 1992-10-26 | 1994-05-11 | UNITED STATES OF AMERICA, as represented by THE UNITED STATES DEPARTMENT OF COMMERCE | Application of microsubstrates for materials processing |
WO1994010822A1 (en) * | 1992-10-26 | 1994-05-11 | THE UNITED STATES OF AMERICA as represented by THEUNITED STATES DEPARTMENT OF COMMERCE | Micro-hotplate devices and methods for their fabrication |
Cited By (16)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6569779B1 (en) | 1998-05-08 | 2003-05-27 | Nordic Sensor Technologies Ab | Device for gas sensing |
US6410445B1 (en) | 1999-01-25 | 2002-06-25 | Appliedsensor Sweden Ab | Manufacturing method for integrated sensor arrays |
WO2002090950A1 (en) * | 2001-05-04 | 2002-11-14 | The University Court Of The University Of Paisley | Optically energised & interrogated sensors |
DE10219726A1 (en) * | 2002-05-02 | 2003-11-27 | Eads Deutschland Gmbh | Production of a bridge-like semiconductor gas sensor comprises preparing a SOI element, forming an electrode arrangement on an electrically insulating layer |
DE102004017750A1 (en) * | 2004-04-06 | 2005-10-27 | Flechsig, Gerd-Uwe, Dr. rer. nat. | Array of heatable electrodes and chemical and biochemical analysis |
DE102004017750B4 (en) * | 2004-04-06 | 2006-03-16 | Flechsig, Gerd-Uwe, Dr. rer. nat. | Analysis array with heatable electrodes |
EP1736768A1 (en) | 2005-06-22 | 2006-12-27 | Appliedsensor Sweden AB | Device and method for gas sensing |
WO2007009948A1 (en) * | 2005-07-15 | 2007-01-25 | Siemens Aktiengesellschaft | Method for the simultaneous detection of a plurality of different types of atmospheric pollution using gas-sensitive field effect transistors |
WO2013092823A1 (en) * | 2011-12-23 | 2013-06-27 | Sanofi-Aventis Deutschland Gmbh | Sensor arrangement for a packaging of a medicament |
AU2012357007B2 (en) * | 2011-12-23 | 2015-08-13 | Sanofi-Aventis Deutschland Gmbh | Sensor arrangement for a packaging of a medicament |
US10215786B2 (en) | 2011-12-23 | 2019-02-26 | Sanofi-Aventis Deutschland Gmbh | Sensor arrangement for a packaging of a medicament |
WO2014012948A1 (en) | 2012-07-16 | 2014-01-23 | Sgx Sensortech Sa | Micro-hotplate device and sensor comprising such micro-hotplate device |
US9228967B2 (en) | 2012-07-16 | 2016-01-05 | Sgx Sensortech Sa | Micro-hotplate device and sensor comprising such micro-hotplate device |
US9716140B2 (en) | 2014-04-02 | 2017-07-25 | Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forschung E. V. | Fluid sensor and method for examining a fluid |
WO2017044267A1 (en) * | 2015-09-09 | 2017-03-16 | Invensense, Inc. | Gas sensor platform and the method of making the same |
US10383967B2 (en) | 2016-11-30 | 2019-08-20 | Invensense, Inc. | Substance sensing with tracers |
Also Published As
Publication number | Publication date |
---|---|
JP2003501657A (en) | 2003-01-14 |
SE9902081L (en) | 2000-12-05 |
SE524102C2 (en) | 2004-06-29 |
EP1190242A1 (en) | 2002-03-27 |
NO20015916D0 (en) | 2001-12-04 |
NO20015916L (en) | 2002-02-01 |
SE9902081D0 (en) | 1999-06-04 |
AU5435400A (en) | 2000-12-28 |
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