JPH0315974B2 - - Google Patents
Info
- Publication number
- JPH0315974B2 JPH0315974B2 JP58228785A JP22878583A JPH0315974B2 JP H0315974 B2 JPH0315974 B2 JP H0315974B2 JP 58228785 A JP58228785 A JP 58228785A JP 22878583 A JP22878583 A JP 22878583A JP H0315974 B2 JPH0315974 B2 JP H0315974B2
- Authority
- JP
- Japan
- Prior art keywords
- mosfet
- gate
- contact hole
- ion
- conductive electrode
- 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.)
- Expired - Lifetime
Links
- 239000000758 substrate Substances 0.000 claims description 12
- 239000010408 film Substances 0.000 description 18
- 150000002500 ions Chemical class 0.000 description 15
- 239000010410 layer Substances 0.000 description 8
- 229910052710 silicon Inorganic materials 0.000 description 8
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 239000010703 silicon Substances 0.000 description 7
- 239000012528 membrane Substances 0.000 description 5
- 229910052782 aluminium Inorganic materials 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- 239000007864 aqueous solution Substances 0.000 description 4
- 238000009413 insulation Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 229910004298 SiO 2 Inorganic materials 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 229910052594 sapphire Inorganic materials 0.000 description 3
- 239000010980 sapphire Substances 0.000 description 3
- 239000010409 thin film Substances 0.000 description 3
- 230000005684 electric field Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 230000002277 temperature effect Effects 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000005669 field effect Effects 0.000 description 1
- 150000002222 fluorine compounds Chemical class 0.000 description 1
- 229910052732 germanium Inorganic materials 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000002161 passivation Methods 0.000 description 1
- 229920000052 poly(p-xylylene) Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 150000003568 thioethers Chemical class 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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
Landscapes
- 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)
Description
【発明の詳細な説明】
＜産業上の利用分野＞
本発明は、電解液中のイオン活量を測定する
ISFETセンサ（電界効果トランジスタ型イオン
センサ）に関し、殊に感応膜組成や光による
MOSFETへの動作影響の解消されたISFETセン
サの提案に関するものである。[Detailed Description of the Invention] <Industrial Application Field> The present invention measures the ionic activity in an electrolytic solution.
Regarding ISFET sensors (field effect transistor type ion sensors), especially due to sensitive film composition and light
This paper relates to a proposal for an ISFET sensor that eliminates the operational influence on MOSFETs.
＜従来技術＞
ISFETセンサは、MOSFETのゲート部上を金
属電極がない状態に構成したもので、その動作原
理もMOSFETと似ている。即ち、水溶液中のイ
オンによつてゲート表面の電位が変化し、これに
よつてゲート絶縁膜下の半導体表面の電導度が変
化してドレイン電流が変化する。従つて、このド
レーン電流の変化からゲート表面電位を検出し、
これによつて水溶液中のイオン活量を測定するこ
とができるのである。この場合、ゲート絶縁膜は
イオン感応膜で構成され、特定のイオン活量を選
択的に測定できるようにしてある。<Prior art> An ISFET sensor is a MOSFET with no metal electrode on the gate, and its operating principle is similar to that of a MOSFET. That is, the potential of the gate surface changes due to the ions in the aqueous solution, which changes the conductivity of the semiconductor surface under the gate insulating film and changes the drain current. Therefore, the gate surface potential is detected from this change in drain current, and
This allows the ionic activity in an aqueous solution to be measured. In this case, the gate insulating film is composed of an ion-sensitive film so that specific ion activity can be selectively measured.
ところで、ISFETセンサの場合、動作原理が
上述の如くゲート表面電位の変化を検出するもの
であるため、従来のイオン電極のようにイオン感
応膜の導電性が問題とならず、従つて膜の選択の
自由度が高く、例えばPHセンサとしてはSiO2，
Si3N4，Al2O3，Ta2O5等の絶縁膜を用いること
ができる。このうちTa2O5膜は理論値に近い応答
を示すものとして注目されている。 By the way, in the case of ISFET sensors, the operating principle is to detect changes in the gate surface potential as described above, so the conductivity of the ion-sensitive membrane is not an issue as with conventional ion electrodes, and therefore the selection of the membrane is For example, as a PH sensor, SiO 2 ,
An insulating film of Si 3 N 4 , Al 2 O 3 , Ta 2 O 5 or the like can be used. Among these, the Ta 2 O 5 film is attracting attention as it exhibits a response close to the theoretical value.
しかしながら、このような優れた特性をもつ反
面ISFETセンサを実用化するためには多くの問
題がある。即ち、ISFETセンサは、室内の光
によつてドリフトすること、水溶液に出し入れ
する際、指示がシフトすること、MOSFETの
動作条件の変動によつてドリフトするため、安定
して長期に計測を行なうことが困難であることと
いつた欠点がある。 However, despite these excellent characteristics, there are many problems in putting ISFET sensors into practical use. In other words, ISFET sensors drift due to indoor light, the indication shifts when placed in and out of an aqueous solution, and drift due to fluctuations in MOSFET operating conditions, so it is important to perform stable measurements over a long period of time. The disadvantage is that it is difficult to
＜発明の目的＞
本発明は、ISFETセンサをMOSFETとイオン
感応膜との組合せと考えることができる点に着目
し、上述した〜の欠点を解消し得る新規構造
のISFETセンサを提供するものである。<Object of the invention> The present invention focuses on the fact that an ISFET sensor can be considered as a combination of a MOSFET and an ion-sensitive membrane, and provides an ISFET sensor with a new structure that can eliminate the above-mentioned drawbacks. .
＜発明の構成＞
上記目的を達成するため、本発明に係る
ISFETセンサは、MOSFETのゲート部から導電
性の電極をゲート領域以外の基板上に延設すると
共に、この延設された導電性電極の表面を、前記
ゲート部から離れたところにコンタクトホールが
形成されるように、高絶縁膜で被覆し、前記コン
タクトホール上にイオン感応膜を設けたことを特
徴としている。ここで導電性電極としては金属の
他にSi，Ge或いは導電性プラスチツク等も使用
でき、水溶液中のイオンによりイオン感応膜に生
じた電位をゲート部まで伝達できるものであれば
材料の如何は問わない。また導電性電極としては
単一の電極に限らず、２つの導電性材料を２段に
直列接続したものでも使用できる。このような使
用例は半導体生産技術を適用する上で絶縁処理し
やすい等の他の利点を生じ好ましいといえる。<Structure of the invention> In order to achieve the above object, the present invention provides
In an ISFET sensor, a conductive electrode is extended from the gate part of the MOSFET onto a substrate other than the gate area, and a contact hole is formed in the surface of the extended conductive electrode at a location away from the gate part. The contact hole is coated with a highly insulating film, and an ion-sensitive film is provided over the contact hole. Here, as the conductive electrode, in addition to metal, Si, Ge, conductive plastic, etc. can be used, and the material does not matter as long as it can transmit the potential generated in the ion-sensitive membrane by the ions in the aqueous solution to the gate part. do not have. Furthermore, the conductive electrode is not limited to a single electrode, but may also be one in which two conductive materials are connected in series in two stages. Such an example of use can be said to be preferable since it has other advantages such as ease of insulation treatment when applying semiconductor production technology.
＜実施例＞
第１図は本発明の一実施例としてのISFETセ
ンサの平面図、第２図はその側断面図を示し、１
はサフアイヤ基板（SOSウエハー）で、その上に
ｐ或いはｎチヤンネルのMOSFETを通常の酸化
−Siアイランド形成、ドレイン・ソース部への不
純物拡散等の標準工程により形成してある。２が
ドレイン、３がソースで、両者の中間にゲート部
４が存している。５，６は導電性の電極としてア
ルミ電極と、それと導電接触したシリコンエピタ
キシヤル層で、MOSFETのゲート部４からゲー
ト領域以外の基板１上の一端部まで延長されてい
る。シリコンエピタキシヤル層６は不純物を高濃
度拡散させることによつて導電性をもたせてあ
る。この層６は前記MOSFETの製作工程と併行
して基板１上に形成することができる。そしてこ
の層６の上には２箇所のコンタクトホール６ａ，
６ｂを残してSiO2，Si3N4、パリレン等の耐水
性、パツシベーシヨン効果のある高絶縁膜７が単
層或いは多層に形成されている。前記アルミ電極
５は一方のコンタクトホール６ａとMOSFETの
ゲート部４との間を結合している。他方のコンタ
クトホール６ｂ上にはイオン感応膜８が形成され
ている。感応膜８がPH、PNa等のガラス材料の
場合、蒸着法、スパツタ法等により薄膜形成でき
る。沸化物、硫化物の場合も同様な方法で形成で
きる。また薄膜片を融着することによつて形成す
ることもできる。イオン感応膜８は図示例ではシ
リコンエピタキシヤル層６の一端部周辺のみに形
成しているが、MOSFETのゲート部４までかか
るように形成することもできる。しかしその場合
はMOSFETのゲート部の光影響を防止するた
め、MOSFETを遮光用のブラツク接着剤等で封
入しておく必要がある。図中、９はリード端子、
１０は接液部以外の部分を封止する樹脂である。<Example> FIG. 1 is a plan view of an ISFET sensor as an example of the present invention, and FIG. 2 is a side sectional view thereof.
is a sapphire substrate (SOS wafer), on which a p- or n-channel MOSFET is formed using standard processes such as forming an oxidation-Si island and diffusing impurities into the drain and source regions. 2 is a drain, 3 is a source, and a gate portion 4 exists between the two. Reference numerals 5 and 6 denote an aluminum electrode as a conductive electrode and a silicon epitaxial layer in conductive contact with the aluminum electrode, which extends from the gate portion 4 of the MOSFET to one end portion of the substrate 1 other than the gate region. The silicon epitaxial layer 6 is made conductive by diffusing impurities at a high concentration. This layer 6 can be formed on the substrate 1 in parallel with the MOSFET manufacturing process. There are two contact holes 6a on this layer 6,
Except for 6b, a highly insulating film 7 made of SiO 2 , Si 3 N 4 , parylene, etc. and having a water resistance and passivation effect is formed in a single layer or in multiple layers. The aluminum electrode 5 connects one contact hole 6a and the gate portion 4 of the MOSFET. An ion sensitive film 8 is formed on the other contact hole 6b. When the sensitive film 8 is made of a glass material such as PH or PNa, a thin film can be formed by a vapor deposition method, a sputtering method, or the like. Fluorides and sulfides can also be formed in a similar manner. It can also be formed by fusing thin film pieces. In the illustrated example, the ion sensitive film 8 is formed only around one end of the silicon epitaxial layer 6, but it can also be formed so as to extend up to the gate part 4 of the MOSFET. However, in that case, in order to prevent the MOSFET gate from being affected by light, it is necessary to encapsulate the MOSFET with a light-shielding black adhesive or the like. In the figure, 9 is a lead terminal,
10 is a resin that seals parts other than the liquid contact parts.
尚、この実施例ではサフアイヤ基板上に
MOSFETを一個のみ形成しているが、２個形成
して一方のMOSFETの温度影響を他方の
MOSFETでキヤンセル方式を採用することがで
きる。また、同一基板上に不済電位の温度影響や
Nernst式の温度影響を補正する薄膜サーミスタ
又はダイオードを形成することもできる。更に同
一基板上に、ゲート過電界防止用の金属電極を形
成し、液交換時にはこの電極を通じてゲートに電
界を加えるように構成することもできる。また基
板１としてはサフアイヤ基板の他のシリコン基板
を用いることもできる。その場合は、シリコンエ
ピタキシヤル層に相当する部分は高濃度拡散して
形成できるし、またシリコン基板の側面にも
SiO2−Si3N4膜を形成することで完全に外部から
絶縁することができる。 In this example, on the sapphire substrate
Although only one MOSFET is formed, two MOSFETs are formed so that the temperature influence of one MOSFET is absorbed by the other MOSFET.
Cancel method can be used with MOSFET. In addition, the temperature effect of undesired potential on the same board
It is also possible to form thin film thermistors or diodes that compensate for Nernst-type temperature effects. Furthermore, it is also possible to form a metal electrode on the same substrate to prevent an excessive electric field at the gate, and to apply an electric field to the gate through this electrode during liquid exchange. Further, as the substrate 1, a silicon substrate other than a sapphire substrate can also be used. In that case, the part corresponding to the silicon epitaxial layer can be formed by high-concentration diffusion, and it can also be formed on the sides of the silicon substrate.
By forming the SiO 2 -Si 3 N 4 film, complete insulation from the outside can be achieved.
＜発明の効果＞
本発明に係るISFETセンサは上述した如く
MOSFETのゲート部から導電性の電極をゲート
領域以外の基板上に延設すると共に、この延設さ
れた導電性電極の表面を、前記ゲート部から離れ
たところにコンタクトホールが形成されるよう
に、高絶縁膜で被覆し、前記コンタクトホール上
にイオン感応膜を設けたものであるから次のよう
な効果がある。<Effects of the Invention> The ISFET sensor according to the present invention has the following effects as described above.
A conductive electrode is extended from the gate part of the MOSFET onto the substrate other than the gate area, and the surface of the extended conductive electrode is formed so that a contact hole is formed at a distance from the gate part. Since the contact hole is coated with a highly insulating film and an ion-sensitive film is provided on the contact hole, the following effects can be obtained.
MOSFETのゲート内に光を入射させない構
造とすることができるため、室内の光によるド
リフトの問題が略々完全に解決できる。 Since it is possible to create a structure that does not allow light to enter the gate of the MOSFET, the problem of drift caused by indoor light can be almost completely solved.
イオン感応膜はゲート部から離れたところに
形成されたコンタクトホール上に設けられてい
ると共に、コンタクトホールが形成される導電
性電極の表面には高絶縁膜で被覆されているの
で、イオン感応膜の組成によつてMOSFETの
動作が影響を受けることがない。従つて、指示
のシフト等がなく長期に亘つて安定した計測が
可能である。 The ion-sensitive film is provided over the contact hole formed at a distance from the gate part, and the surface of the conductive electrode where the contact hole is formed is coated with a highly insulating film. The operation of the MOSFET is not affected by the composition of the MOSFET. Therefore, stable measurement is possible over a long period of time without any shifts in instructions.
導電性電極を実施例で述べたようにアルミ電
極とシリコンエピタキシヤル層とを結合して構
成すれば、エピタキシヤル層の絶縁が容易なた
め、絶縁処理が行ない易く、量産性、信頼性が
向上するという利点も併せ持つ。 If the conductive electrode is constructed by combining an aluminum electrode and a silicon epitaxial layer as described in the examples, it is easy to insulate the epitaxial layer, making the insulation process easier, improving mass productivity and reliability. It also has the advantage of
図は本発明の一実施例を示し、第１図は全体平
面図、第２図はその側断面図である。
４……ゲート部、５，６……導電性電極、６ｂ
……コンタクトホール、７……高絶縁膜、８……
イオン感応膜。
The figures show one embodiment of the present invention, with FIG. 1 being an overall plan view and FIG. 2 being a side sectional view thereof. 4... Gate part, 5, 6... Conductive electrode, 6b
...Contact hole, 7...High insulation film, 8...
Ion sensitive membrane.
Claims (1)
ート領域以外の基板上に延設すると共に、この延
設された導電性電極の表面を、前記ゲート部から
離れたところにコンタクトホールが形成されるよ
うに、高絶縁膜で被覆し、前記コンタクトホール
上にイオン感応膜を設けたことを特徴とする
ISFETセンサ。1. A conductive electrode is extended from the gate part of the MOSFET onto the substrate other than the gate area, and the surface of the extended conductive electrode is formed so that a contact hole is formed at a distance from the gate part. The contact hole is coated with a highly insulating film and an ion-sensitive film is provided on the contact hole.
ISFET sensor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58228785A JPS60120240A (en) | 1983-12-03 | 1983-12-03 | Isfet sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58228785A JPS60120240A (en) | 1983-12-03 | 1983-12-03 | Isfet sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60120240A JPS60120240A (en) | 1985-06-27 |
| JPH0315974B2 true JPH0315974B2 (en) | 1991-03-04 |
Family
ID=16881805
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP58228785A Granted JPS60120240A (en) | 1983-12-03 | 1983-12-03 | Isfet sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60120240A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1250020A (en) * | 1985-01-23 | 1989-02-14 | Imants R. Lauks | Ambient sensing devices with isolation |
| JPS62132160A (en) * | 1985-12-04 | 1987-06-15 | Terumo Corp | Biosensor using separation gate type isfet |
| US4889612A (en) * | 1987-05-22 | 1989-12-26 | Abbott Laboratories | Ion-selective electrode having a non-metal sensing element |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5630640A (en) * | 1979-08-22 | 1981-03-27 | Olympus Optical Co Ltd | Detecting method of chemical substance by chemically sensitive element of insulated-gate transistor structure |
-
1983
- 1983-12-03 JP JP58228785A patent/JPS60120240A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5630640A (en) * | 1979-08-22 | 1981-03-27 | Olympus Optical Co Ltd | Detecting method of chemical substance by chemically sensitive element of insulated-gate transistor structure |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60120240A (en) | 1985-06-27 |
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