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WO2011049428A1 - Isfet inverse - Google Patents

Isfet inverse Download PDF

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Publication number
WO2011049428A1
WO2011049428A1 PCT/MY2010/000215 MY2010000215W WO2011049428A1 WO 2011049428 A1 WO2011049428 A1 WO 2011049428A1 MY 2010000215 W MY2010000215 W MY 2010000215W WO 2011049428 A1 WO2011049428 A1 WO 2011049428A1
Authority
WO
WIPO (PCT)
Prior art keywords
layer
sensing membrane
isfet
drain
regions
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/MY2010/000215
Other languages
English (en)
Inventor
Daniel Chia Sheng Bien
Hing Wah Lee
Mohd Ismahadi Syono
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mimos Bhd
Original Assignee
Mimos Bhd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mimos Bhd filed Critical Mimos Bhd
Publication of WO2011049428A1 publication Critical patent/WO2011049428A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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

Definitions

  • the present invention relates to ion-sensitive field effect transistor ( ISFET ) , more particularly relates to a ISFET having isolation of the fluid interacting sensing membrane area with the electrical conducting area.
  • ISFET ion-sensitive field effect transistor
  • Chemical sensors for detecting chemical compounds are widely used in different field such as medical diagnosis, water treatment system, food processing and the like.
  • Conventional chemical sensor such as glass electrode and spectrophotometer are relatively large in size, difficult to be handled, and expensive as required lots of building parts for construction.
  • miniaturized semiconductor sensors were devised and now replacing the use of conventional chemical sensor.
  • ISFET Ion-sensitive field effect transistor
  • ISFETs have metal contacts and the sensing gate on the same surface of the wafer hence they require separate packaging module so that only the gate will be in contact with the liquid sample.
  • the metal contacts and the sensing gate are on different thickness level , therefore this creates packaging problem such as alignment during packaging process, leakage, bonding performance, etc 0
  • Those ISFETs have high current losses and leakage issues as only a minimum part of the substrate itself would be required to build the FET while other large silicon conducting area will be omitted from the device application but which, will indirectly affect the performance of the ISFET. They are also fabricated on bulk thick substrate where it has been associated with problems such as low saturation current and reduced short-channel/floating body effects.
  • US Patent Publication No. 7321143 discloses an ion-sensitive field effect transistor includes a substrate on which there are formed a source region and a drain region. Above a channel region, the ion-sensitive field effect transistor has a gate with a sensitive layer including a metal oxide nitride mixture and/or a metal oxide nitride mixture compound.
  • US Patent Publication No. 7321143 discloses an integrated ion sensor, which comprises at least one ion selective membrane sensitive to ions contained in a solution to be measured for detecting the concentration of the ions, a signal processing circuit for inputting a detected signal obtained by the ion selective membrane through a conductive member and fetching the detected signal through MOSFETs or the like included in an input stage to process the same, a reference electrode disposed in the measuring environment made by the solution to be measured and to be set to a predetermined voltage relationship between the reference electrode and the ion selective membrane, and a power supply having negative and positive terminals for supplying a driving power to the signal processing circuit through the terminals, one of the terminals being connected to the reference electrode, wherein the signal processing circuit is set to an active state at a voltage set to the reference electrode, by controlling the threshold value of at least one of the MOSFETs of the signal processing circuit.
  • the present invention is an inverted ISFET with the sensing membrane and metal contact pads on opposing sides of the substrate 0
  • This improved configuration allow isolation of the fluid interacting sensing membrane area with the electrical conducting area by reducing the possibility of the electrical circuit being shorted due to the presence of the conducting fluids 0
  • ISFET sensor which is integrated or self-formed with sensing window on the sensing membrane hence allowing the elimination of the bonding requirement to attach the sensing window or packaging onto the sensing membrane and therefore fluid leakage problems will be improved and addressed leading to a leakage-free fluid-sensing membrane interface area Q
  • Still another objective of the present invention is to provide the ISFET sensor which can be microfabricated for miniaturization purpose 0
  • an inverted ion-sensitive field effect transistor comprises a substrate layer, a sensing membrane on the substrate layer, a layer of field oxide on the sensing membrane, doped source and drain regions on the layer of field oxide, and characterized in that electrical contacts are provided to the respective source and drain regions on the opposing side of the sensing membrane and the substrate layer is windowed with an opening access to the sensing membrane to provide electrical isolation of the electrical contacts from the sensing membrane .
  • a method of manufacturing an inverted ISFET comprising the steps of providing a substrate layer, depositing a layer of sensing membrane on the substrate layer, depositing a layer of field oxide on the sensing membrane, depositing a layer of doped polysilicon on the field oxide layer, etching the respective source and drain regions using photoresist, and providing the electrical contacts for the source and drain regions, characterized in that the electrical contacts are provided on the opposing side of the sensing membrane to provide electrical isolation of the electrical contacts from the sensing membrane.
  • Figure 1 shows a schematic diagram of the ISFET of .
  • Figure 2 depicts an inverted ISFET of the present invention
  • Figure 3 is a step by step fabrication process flow of the inverted ISFET of the present invention which are shown in Figure 3a to 3m.
  • an inverted ion-sensitive field effect transistor ( ISFET ) of the present invention generally designated as numeral reference 10 0
  • Figure 2 shows a cross sectional view of the inverted ISFET ( 10 ) having the desired configuration as obtained when manufactured in accordance to the present invention
  • the substrate ( 11 ) of the inverted ISFET ( 10 ) is a polysilicon layer which is a thin film silicon based layer in order to provide an improved performance of the ISFETo
  • the substrate ( 11 ) is not limited to silicon but other types of substrates such as glass , SOI , etc can also be used to realize the device fabrication,,
  • sensing membrane ( 12 ) On the front side of the substrate ( 11 ) , it is deposited with a layer of sensing membrane ( 12 ) which is preferably a nitride sensing membrane such as silicon nitride ( Si 3 N 4 ) 0
  • the inverted ISFET ( 10 ) is doped to have a source region ( 13 ) and a drain region ( 14 ) o In between the source ( 13 ) and drain ( 14 ) regions there is a doped polysilicon area ( 15 ).
  • the source region ( 13 ) is provided with a metal source contact ( 16 ) and the drain region ( 14 ) is provided with a metal drain contact ( 17 ) 0
  • These contacts ( 16 , 17 ) and the sensing membrane ( 12 ) are on the opposing side of the substrate ( 11 ) 0
  • the method of manufacturing the inverted ISFET ( 10 ) of the present invention is now describedo
  • the process is started with a wafer of silicon as the substrate ( 11 ) of the inverted ISFET ( 10 ) 0
  • the substrate ( 11 ) is then deposited (31) with a layer of sensing membrane ( 12 ) and a layer of field oxide ( 19 ) at the front of the substrate ( 11 ) as shown in Figure 3a 0
  • the sensing membrane ( 12 ) is a silicon nitride ( Si 3 N 4 ) layer and the field oxide layer ( 19 ) is a silicon dioxide ( Si0 2 ) layer 0
  • a layer of doped polysilicon ( 15 ) is then deposited (32) on the field oxide layer ( 19 ) as shown in Figure 3b.
  • a sacrificial layer of field oxide ' ( 20 ) is deposited (33) on the doped polysilicon layer (15) and followed by a layer of silicon nitride ( Si 3 N 4 ) (21) as shown in Figure 3c.
  • the sacrificial layer of field oxide (20) is a layer of silicon dioxide (Si0 2 ) .
  • the process is then followed with a resist coating and patterning (34) to cover the part that is not to be etched as shown in Figure 3d.
  • the doped polysilicon layer (15) is etched (35) with the source (13) and drain (14) regions using photoresist as shown in Figure 3e.
  • the resist coating is then removed and performed (36) a channeling implant as shown in Figure 3f.
  • the sacrificial layer of field oxide ( 20 ) and the layer of silicon nitride ( Si 3 N 4 ) are then removed (37) as shown in Figure 3g.
  • a protective layer of field oxide (23) is then deposited (38) on the wafer as shown in Figure 3h.
  • the protective layer of field oxide (23) is a layer of silicon dioxide (Si0 2 ) .
  • a resist coating and patterning (25) for contact pad (22) is then performed (39) on the wafer leaving openings to provide access to the source (13) and drain (14) regions as shown in Figure 3i.
  • the protective layer of silicon dioxide (Si0 2 ) is etched (40) respectively towards both source (13) and drain (14) regions, to provide contact access to said regions as shown in Figure 3j .
  • the resist coating (23) is then removed and the metal contact pad (22) is sputtered (41) on the wafer as shown in Figure 3k.
  • a resist coating and patterning (24) for metal etching is then performed (42) on the wafer leaving the center portion uncovered as shown in Figure 31.
  • the middle portion from the back of the substrate (11) is then etched (45) using deep reactive ion etching (DRIE) or wet etching until the sensing membrane layer (12) to provide the window opening (18) to the sensing membrane (12) hence eliminating the requirement of the bonding process and additional substrate or packaging material.
  • DRIE deep reactive ion etching
  • the metal contacts (16, 17) are provided on the opposing side of the sensing membrane (12), thus, when user injects samples to the opening window at the sensing membrane (12) the fluid will be isolated from the electrical conducting area hence prevents electrical shorting from occurring as shown in Figure 3o.
  • the present invention is not limited in its present form and can be configured with additional features.
  • the bottom of the substrate (11) can be etched or constructed with, but not limited to, microfluidic features such as microchannel , reservoir, micromixers, etc near the sensing membrane (12) area upon the formation of the opening window.

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  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Molecular Biology (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)

Abstract

L'invention concerne un transistor à effet de champ inverse sensible aux ions (ISFET) (10) comprenant une couche de substrat (11), une membrane de détection (12) placée sur la couche de substrat (11), une couche d'oxyde de champ (19) placée sur la membrane de détection (12), des régions de source (13) et de drain (14) dopées placées sur la couche d'oxyde de champ (19), et caractérisées en ce que les contacts électriques (16, 17) sont situés sur les régions de source (13) et de drain (14) respectives sur le côté opposé de la membrane de détection (12), la couche de substrat (11) comprenant un fenêtrage à ouverture d'accès (18) à la membrane de détection (12) permettant d'isoler électriquement les contacts électriques (16, 17) à partir de ladite membrane de détection (12).
PCT/MY2010/000215 2009-10-20 2010-10-19 Isfet inverse Ceased WO2011049428A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
MYPI20094402A MY162299A (en) 2009-10-20 2009-10-20 Inverted isfet and method of producing thereof
MYPI20094402 2009-10-20

Publications (1)

Publication Number Publication Date
WO2011049428A1 true WO2011049428A1 (fr) 2011-04-28

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ID=43900498

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/MY2010/000215 Ceased WO2011049428A1 (fr) 2009-10-20 2010-10-19 Isfet inverse

Country Status (2)

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MY (1) MY162299A (fr)
WO (1) WO2011049428A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015178754A1 (fr) * 2014-05-20 2015-11-26 Mimos Berhad Isfet intégré avec un micro-chauffage et son procédé de fabrication
US9541521B1 (en) 2015-10-30 2017-01-10 Nxp Usa, Inc. Enhanced sensitivity ion sensing devices

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0363805A1 (fr) * 1988-10-10 1990-04-18 ENIRICERCHE S.p.A. Un capteur chimique monolithique du type Chemfet, comprenant une membrane ionosensible, et son procédé de fabrication
US4961833A (en) * 1988-03-31 1990-10-09 Kabushiki Kaisha Toshiba Field-effect transistor-type semiconductor sensor
WO1994022006A1 (fr) * 1993-03-13 1994-09-29 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Composant semi-conducteur, notamment pour la detection d'ions
US20050186697A1 (en) * 2003-05-09 2005-08-25 Au Optronics Corp. Fabrication method of an ion sensitive field effect transistor

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4961833A (en) * 1988-03-31 1990-10-09 Kabushiki Kaisha Toshiba Field-effect transistor-type semiconductor sensor
EP0363805A1 (fr) * 1988-10-10 1990-04-18 ENIRICERCHE S.p.A. Un capteur chimique monolithique du type Chemfet, comprenant une membrane ionosensible, et son procédé de fabrication
WO1994022006A1 (fr) * 1993-03-13 1994-09-29 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Composant semi-conducteur, notamment pour la detection d'ions
US20050186697A1 (en) * 2003-05-09 2005-08-25 Au Optronics Corp. Fabrication method of an ion sensitive field effect transistor

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015178754A1 (fr) * 2014-05-20 2015-11-26 Mimos Berhad Isfet intégré avec un micro-chauffage et son procédé de fabrication
US9541521B1 (en) 2015-10-30 2017-01-10 Nxp Usa, Inc. Enhanced sensitivity ion sensing devices

Also Published As

Publication number Publication date
MY162299A (en) 2017-05-31

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