JP2000187018A - Semiconductor ion sensor - Google Patents
Semiconductor ion sensorInfo
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- JP2000187018A JP2000187018A JP10363961A JP36396198A JP2000187018A JP 2000187018 A JP2000187018 A JP 2000187018A JP 10363961 A JP10363961 A JP 10363961A JP 36396198 A JP36396198 A JP 36396198A JP 2000187018 A JP2000187018 A JP 2000187018A
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- Prior art keywords
- source
- isfet
- drain
- electrode
- region
- Prior art date
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、半導体イオンセン
サに関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor ion sensor.
【０００２】[0002]
【従来の技術】従来より、溶液（測定液）中のイオンの
濃度（活量）を電気信号に変換するデバイスとしてＩＳ
ＦＥＴ（Ion Sensitive Field Effect Transisto
r）と呼ばれる半導体イオンセンサが提供されている。
この種の半導体イオンセンサは、図３に示すように、ｐ
形シリコン基板１の主表面側にｎ+層よりなるドレイン
領域２とｎ+層よりなるソース領域３とが離間して形成
され、両領域２，３間のチャネル部４上にゲート絶縁膜
５を介してイオン感応膜６が形成されている。また、ド
レイン領域２上にはドレイン電極７が形成され、ソース
領域３上にはソース電極８が形成されており、各電極
７，８上には保護膜１０が形成されている。なお、図３
中の９はフィールド酸化膜を示す。2. Description of the Related Art Conventionally, as a device for converting the concentration (activity) of ions in a solution (measurement solution) into an electric signal, IS
FET (Ion Sensitive Field Effect Transisto)
A semiconductor ion sensor called r) is provided.
As shown in FIG. 3, this type of semiconductor ion sensor has p
A drain region 2 composed of an n + layer and a source region 3 composed of an n + layer are formed on the main surface side of the silicon substrate 1 at a distance, and a gate insulating film 5 is formed on a channel portion 4 between the two regions 2 and 3. The ion-sensitive film 6 is formed via the substrate. A drain electrode 7 is formed on the drain region 2, a source electrode 8 is formed on the source region 3, and a protective film 10 is formed on each of the electrodes 7 and 8. Note that FIG.
Reference numeral 9 denotes a field oxide film.
【０００３】要するに、図３に示す構成のＩＳＦＥＴ
は、電界効果型トランジスタのドレイン・ソース間のチ
ャネル部上にゲート絶縁膜を介して形成されたゲート電
極に相当する部分に、イオン感応膜６を形成してある。
したがって、ＩＳＦＥＴでは、イオン濃度の大きさに応
じてチャネル部４の電位が変わってチャネル部４の電気
抵抗が変化することになり、ドレイン・ソース間の電流
が変化する。In short, the ISFET having the configuration shown in FIG.
Has an ion-sensitive film 6 formed at a portion corresponding to a gate electrode formed on a channel portion between a drain and a source of a field-effect transistor via a gate insulating film.
Therefore, in the ISFET, the electric potential of the channel portion 4 changes according to the magnitude of the ion concentration, so that the electric resistance of the channel portion 4 changes, and the current between the drain and the source changes.
【０００４】この種の半導体イオンセンサでは、ＩＳＦ
ＥＴと別体の参照電極３０をＩＳＦＥＴのソース電極８
に可変電圧源Ｖａを介して接続し、溶液（測定液）の電
位を参照電極３０を通してＩＳＦＥＴのソース電位に対
して一定の値にすることにより、ソース・ゲート間には
イオンの濃度に応じた電圧が加わるから、ドレイン電極
７・ソース電極８間に電圧源Ｖ２を介して挿入された電
流計４０による測定電流によりイオン濃度を知ることが
できる。In this type of semiconductor ion sensor, ISF
The reference electrode 30 separate from the ET is connected to the source electrode 8 of the ISFET.
To a constant voltage with respect to the source potential of the ISFET by setting the potential of the solution (measurement solution) to a constant value with respect to the source potential of the ISFET through the reference electrode 30. Since a voltage is applied, the ion concentration can be determined from the current measured by the ammeter 40 inserted between the drain electrode 7 and the source electrode 8 via the voltage source V2.
【０００５】[0005]
【発明が解決しようとする課題】ところで、上記従来構
成の半導体イオンセンサでは、製品ごとのＩＳＦＥＴの
しきい値電圧Ｖｔｈの違いや温度特性などにより、参照
電極３０へ印加する最適な電圧が製品ごとに異なってお
り、ＩＳＦＥＴのしきい値電圧Ｖｔｈのばらつきや温度
変化に関わらず一定の感度および精度を保つために、可
変電圧源Ｖａによる参照電極３０への印加電圧をその都
度調整する必要があり、手間がかかるという不具合があ
った。In the above-described conventional semiconductor ion sensor, the optimum voltage to be applied to the reference electrode 30 depends on the product due to the difference in the threshold voltage Vth of the ISFET for each product and the temperature characteristics. It is necessary to adjust the voltage applied to the reference electrode 30 by the variable voltage source Va in order to maintain a constant sensitivity and accuracy regardless of variations in the threshold voltage Vth of the ISFET and temperature changes. There was a problem that it took time and effort.
【０００６】本発明は上記事由に鑑みて為されたもので
あり、その目的は、参照電極への印加電圧を調整する作
業が不要で安定した感度特性を有する半導体イオンセン
サを提供することにある。The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a semiconductor ion sensor which does not require an operation of adjusting a voltage applied to a reference electrode and has stable sensitivity characteristics. .
【０００７】[0007]
【課題を解決するための手段】請求項１の発明は、上記
目的を達成するために、半導体基板の主表面側にドレイ
ン領域とソース領域とが離間して形成され、半導体基板
においてドレイン領域とソース領域との間に介在する領
域上に絶縁膜を介してイオン感応膜が形成され、ドレイ
ン領域上にドレイン電極が形成され、ソース領域上にソ
ース電極が形成されたＩＳＦＥＴと、ＩＳＦＥＴのソー
ス電極に接続された参照電極と、該参照電極とＩＳＦＥ
Ｔのソース電極との間に挿入されＩＳＦＥＴのしきい値
電圧と略同じしきい値電圧を有するＦＥＴであってドレ
インおよびゲートが参照電極に接続され、ソースがＩＳ
ＦＥＴのソース電極に接続された定電圧用ＦＥＴと、定
電圧用ＦＥＴのドレイン・ソース間に並列接続される電
流制御用抵抗と電圧源との直列回路とを備えることを特
徴とするものであり、参照電極の電位をＩＳＦＥＴのし
きい値電圧に略一致させることができるので、従来のよ
うに参照電極に印加する電圧を調整するような作業が不
要で、半導体イオンセンサの感度特性が温度変化やＩＳ
ＦＥＴのしきい値電圧Ｖｔｈのばらつきなどがあっても
変わることなく、製品ごとの感度特性のばらつきが小さ
い安定した感度特性を有する。According to a first aspect of the present invention, in order to achieve the above object, a drain region and a source region are formed on a main surface side of a semiconductor substrate so as to be separated from each other. An ISFET in which an ion-sensitive film is formed on a region interposed between the source region and an insulating film, a drain electrode is formed on a drain region, and a source electrode is formed on a source region; And a reference electrode connected to the
An FET having a threshold voltage substantially the same as that of the ISFET inserted between the source electrode of T and the drain and the gate connected to the reference electrode;
A constant voltage FET connected to the source electrode of the FET, and a series circuit of a current control resistor and a voltage source connected in parallel between the drain and the source of the constant voltage FET. Since the potential of the reference electrode can be made substantially equal to the threshold voltage of the ISFET, there is no need to adjust the voltage applied to the reference electrode as in the prior art, and the sensitivity characteristics of the semiconductor ion sensor change with temperature. And IS
Even if there is a variation in the threshold voltage Vth of the FET, it does not change and has a stable sensitivity characteristic in which the variation in the sensitivity characteristic for each product is small.
【０００８】請求項２の発明は、請求項１の発明におい
て、定電圧用ＦＥＴとＩＳＦＥＴとは隣接して同一半導
体基板に形成され、両ＦＥＴのソース領域が共通化され
ているので、両ＦＥＴのしきい値電圧を容易に一致させ
ることができ製品ごとの感度特性のばらつきがより小さ
くなるとともに、センサの小型化を図ることができる。According to a second aspect of the present invention, in the first aspect of the present invention, the constant voltage FET and the ISFET are formed adjacent to each other on the same semiconductor substrate, and the source regions of both the FETs are shared. Can be easily matched with each other, the variation in the sensitivity characteristic of each product can be reduced, and the size of the sensor can be reduced.
【０００９】[0009]
【発明の実施の形態】（実施形態１）本実施形態の半導
体イオンセンサの基本構成は図３に示した従来構成と略
同じであって、図１に示すように、参照電極３０とＩＳ
ＦＥＴのソース電極８との間に、ＩＳＦＥＴのしきい値
電圧と略同じしきい値電圧を有するＭＯＳＦＥＴであっ
てドレインおよびゲートが参照電極３０に接続されソー
スがＩＳＦＥＴのソース電極８に接続された定電圧用Ｍ
ＯＳＦＥＴ２０を設けるとともに、電流制御用抵抗Ｒと
電圧源Ｖ１との直列回路を定電圧用ＭＯＳＦＥＴ２０の
ドレイン・ソース間に並列接続した点に特徴がある。な
お、図３に示した従来構成と同様の構成要素には同一の
符号を付して説明を省略する。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) The basic configuration of a semiconductor ion sensor according to this embodiment is substantially the same as the conventional configuration shown in FIG. 3, and as shown in FIG.
A MOSFET having a threshold voltage substantially equal to the threshold voltage of the ISFET between the source electrode 8 of the FET and a drain and a gate connected to the reference electrode 30 and a source connected to the source electrode 8 of the ISFET; M for constant voltage
The feature is that the OSFET 20 is provided, and a series circuit of the current control resistor R and the voltage source V1 is connected in parallel between the drain and the source of the constant voltage MOSFET 20. Note that the same components as those in the conventional configuration shown in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted.
【００１０】ここにおいて、定電圧用ＭＯＳＦＥＴ２０
は、ゲート・ドレイン間が短絡され、ドレイン・ソース
間に上記直列回路が並列接続されているので、定電圧源
として機能し、参照電極３０の電位を常にＩＳＦＥＴの
ドレイン電流が流れ始める電位に保つことができる。Here, the constant voltage MOSFET 20
Functions as a constant voltage source because the gate and drain are short-circuited and the series circuit is connected in parallel between the drain and source, and always keeps the potential of the reference electrode 30 at the potential at which the drain current of the ISFET starts flowing. be able to.
【００１１】しかして、本実施形態の半導体イオンセン
サでは、参照電極３０の電位をＩＳＦＥＴのしきい値電
圧に略一致させることができるから、従来のように参照
電極３０に印加する電圧を可変電圧源Ｖａ（図３参照）
によって調整するような作業が不要で、温度変化やＩＳ
ＦＥＴのしきい値電圧Ｖｔｈのばらつきなどがあっても
感度特性が変わることなく、製品ごとの感度特性のばら
つきが小さくなり、感度特性が安定する。In the semiconductor ion sensor according to the present embodiment, the potential of the reference electrode 30 can be made substantially equal to the threshold voltage of the ISFET. Source Va (see FIG. 3)
No adjustment work is required by temperature change or IS
Even if there is a variation in the threshold voltage Vth of the FET, the sensitivity characteristic does not change, the variation in the sensitivity characteristic for each product is reduced, and the sensitivity characteristic is stabilized.
【００１２】（実施形態２）本実施形態の半導体イオン
センサの基本構成は図１に示した従来構成と略同じであ
って、図２に示すように、実施形態１の定電圧用ＭＯＳ
ＦＥＴ２０をＩＳＦＥＴが形成されたｐ形シリコン基板
１に形成し、ソース領域３を共通化した点に特徴があ
る。すなわち、本実施形態では、ＩＳＦＥＴと定電圧用
ＭＯＳＦＥＴ２０とが１チップ内に隣接して形成されて
いる。なお、実施形態１と同様の構成要素には同一の符
号を付して説明を省略する。(Embodiment 2) The basic configuration of a semiconductor ion sensor of this embodiment is substantially the same as the conventional configuration shown in FIG. 1, and as shown in FIG.
The feature is that the FET 20 is formed on the p-type silicon substrate 1 on which the ISFET is formed, and the source region 3 is shared. That is, in this embodiment, the ISFET and the constant voltage MOSFET 20 are formed adjacent to each other in one chip. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.
【００１３】定電圧用ＭＯＳＦＥＴ２０は、ＩＳＦＥＴ
が形成されたｐ形シリコン基板１のの主表面側にｎ+層
よりなるドレイン領域２’とソース領域３とが離間して
形成され、両領域２’，３間のチャネル部４’上にゲー
ト絶縁膜１５を介してゲート電極１６が形成されてい
る。また、ドレイン領域２’上にはドレイン電極７’が
形成され、ソース領域３上にはソース電極８が形成され
ており、各電極７，８，１６上には保護膜１０が形成さ
れている。ここに、定電圧用ＭＯＳＦＥＴ２０のソース
領域３およびソース電極８はＩＳＦＥＴと共通である。The constant voltage MOSFET 20 is an ISFET
There 'is formed apart from the source region 3 is, the two regions 2' drain region 2 formed of the n + layer on the main surface of the formed p-type silicon substrate 1, over the channel portion 4 'between 3 A gate electrode 16 is formed via a gate insulating film 15. A drain electrode 7 'is formed on the drain region 2', a source electrode 8 is formed on the source region 3, and a protective film 10 is formed on each of the electrodes 7, 8, and 16. . Here, the source region 3 and the source electrode 8 of the constant voltage MOSFET 20 are common to the ISFET.
【００１４】しかして、本実施形態の半導体イオンセン
サでは、ＩＳＦＥＴと定電圧用ＭＯＳＦＥＴ２０とが同
一チップに形成されソース領域３が共通化されているの
で、ＩＳＦＥＴのしきい値電圧と定電圧用ＭＯＳＦＥＴ
２０のしきい値電圧とを容易に一致させることができ製
品ごとの感度特性のばらつきがより小さくなるととも
に、両ＦＥＴを別々のチップに形成する場合やソース領
域３を共通化しない場合に比べてセンサの小型化を図る
ことができる。In the semiconductor ion sensor of this embodiment, the ISFET and the constant voltage MOSFET 20 are formed on the same chip and the source region 3 is shared, so that the threshold voltage of the ISFET and the constant voltage MOSFET
20 can be easily matched with each other, and the variation in sensitivity characteristics between products can be reduced. Further, compared to a case where both FETs are formed on separate chips or a case where the source region 3 is not shared. The size of the sensor can be reduced.
【００１５】[0015]
【発明の効果】請求項１の発明は、半導体基板の主表面
側にドレイン領域とソース領域とが離間して形成され、
半導体基板においてドレイン領域とソース領域との間に
介在する領域上に絶縁膜を介してイオン感応膜が形成さ
れ、ドレイン領域上にドレイン電極が形成され、ソース
領域上にソース電極が形成されたＩＳＦＥＴと、ＩＳＦ
ＥＴのソース電極に接続された参照電極と、該参照電極
とＩＳＦＥＴのソース電極との間に挿入されＩＳＦＥＴ
のしきい値電圧と略同じしきい値電圧を有するＦＥＴで
あってドレインおよびゲートが参照電極に接続され、ソ
ースがＩＳＦＥＴのソース電極に接続された定電圧用Ｆ
ＥＴと、定電圧用ＦＥＴのドレイン・ソース間に並列接
続される電流制御用抵抗と電圧源との直列回路とを備え
るので、参照電極の電位をＩＳＦＥＴのしきい値電圧に
略一致させることができるから、従来のように参照電極
に印加する電圧を調整するような作業が不要で、半導体
イオンセンサの感度特性が温度変化やＩＳＦＥＴのしき
い値電圧Ｖｔｈのばらつきなどがあっても変わることな
く、製品ごとの感度特性のばらつきが小さい安定した感
度特性を有するという効果がある。According to the first aspect of the present invention, a drain region and a source region are formed on a main surface side of a semiconductor substrate with a space therebetween.
An ISFET in which an ion-sensitive film is formed on a region interposed between a drain region and a source region on a semiconductor substrate via an insulating film, a drain electrode is formed on the drain region, and a source electrode is formed on the source region And ISF
A reference electrode connected to the source electrode of the ET; and an ISFET inserted between the reference electrode and the source electrode of the ISFET.
Having a threshold voltage substantially the same as the threshold voltage of the constant-voltage FET whose drain and gate are connected to the reference electrode and whose source is connected to the source electrode of the ISFET.
Since the ET and the series circuit of the current control resistor and the voltage source connected in parallel between the drain and the source of the constant voltage FET are provided, the potential of the reference electrode can be made substantially equal to the threshold voltage of the ISFET. Therefore, it is not necessary to adjust the voltage applied to the reference electrode as in the related art, and the sensitivity characteristics of the semiconductor ion sensor do not change even if there is a temperature change or a variation in the threshold voltage Vth of the ISFET. In addition, there is an effect that the device has stable sensitivity characteristics with small variations in sensitivity characteristics for each product.
【００１６】請求項２の発明は、請求項１の発明におい
て、定電圧用ＦＥＴとＩＳＦＥＴとは隣接して同一半導
体基板に形成され、両ＦＥＴのソース領域が共通化され
ているので、両ＦＥＴのしきい値電圧を容易に一致させ
ることができ製品ごとの感度特性のばらつきがより小さ
くなるとともに、センサの小型化を図ることができると
いう効果がある。According to a second aspect of the present invention, in the first aspect of the present invention, the constant voltage FET and the ISFET are formed on the same semiconductor substrate adjacent to each other, and the source regions of both the FETs are shared. And the threshold voltage of the sensor can be easily matched, the variation in the sensitivity characteristic of each product can be reduced, and the size of the sensor can be reduced.
【図１】実施形態１を示す概略構成図である。FIG. 1 is a schematic configuration diagram showing a first embodiment.
【図２】実施形態２を示す概略構成図である。FIG. 2 is a schematic configuration diagram showing a second embodiment.
【図３】従来例を示す概略構成図である。FIG. 3 is a schematic configuration diagram showing a conventional example.
１ ｐ形シリコン基板 ２ ドレイン領域 ３ ソース領域 ４ チャネル部 ５ ゲート絶縁膜 ６ イオン感応膜 ７ ドレイン電極 ８ ソース電極 ９ フィールド酸化膜 １０ 保護膜 ２０ 定電圧用ＭＯＳＦＥＴ ３０ 参照電極 Ｒ 電流制御用抵抗 Ｖ１ 電圧源 REFERENCE SIGNS LIST 1 p-type silicon substrate 2 drain region 3 source region 4 channel portion 5 gate insulating film 6 ion sensitive film 7 drain electrode 8 source electrode 9 field oxide film 10 protective film 20 constant voltage MOSFET 30 reference electrode R current control resistance V1 voltage source
Claims (2)
ソース領域とが離間して形成され、半導体基板において
ドレイン領域とソース領域との間に介在する領域上に絶
縁膜を介してイオン感応膜が形成され、ドレイン領域上
にドレイン電極が形成され、ソース領域上にソース電極
が形成されたＩＳＦＥＴと、ＩＳＦＥＴのソース電極に
接続された参照電極と、該参照電極とＩＳＦＥＴのソー
ス電極との間に挿入されＩＳＦＥＴのしきい値電圧と略
同じしきい値電圧を有するＦＥＴであってドレインおよ
びゲートが参照電極に接続され、ソースがＩＳＦＥＴの
ソース電極に接続された定電圧用ＦＥＴと、定電圧用Ｆ
ＥＴのドレイン・ソース間に並列接続される電流制御用
抵抗と電圧源との直列回路とを備えることを特徴とする
半導体イオンセンサ。A drain region and a source region are formed on a main surface side of a semiconductor substrate so as to be separated from each other, and an ion-sensitive film is provided on a region interposed between the drain region and the source region in the semiconductor substrate via an insulating film. Is formed, a drain electrode is formed on the drain region, a source electrode is formed on the source region, a reference electrode connected to the source electrode of the ISFET, and between the reference electrode and the source electrode of the ISFET. A constant-voltage FET having a threshold voltage substantially equal to the threshold voltage of the ISFET, the drain and the gate of which are connected to the reference electrode, and the source connected to the source electrode of the ISFET; For F
A semiconductor ion sensor comprising: a series circuit of a current control resistor and a voltage source connected in parallel between a drain and a source of an ET.
て同一半導体基板に形成され、両ＦＥＴのソース領域が
共通化されてなることを特徴とする請求項１記載の半導
体イオンセンサ。2. The semiconductor ion sensor according to claim 1, wherein the constant voltage FET and the ISFET are formed adjacent to each other on the same semiconductor substrate, and the source regions of both FETs are shared.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP36396198A JP3982090B2 (en) | 1998-12-22 | 1998-12-22 | Semiconductor ion sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP36396198A JP3982090B2 (en) | 1998-12-22 | 1998-12-22 | Semiconductor ion sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000187018A true JP2000187018A (en) | 2000-07-04 |
| JP3982090B2 JP3982090B2 (en) | 2007-09-26 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP36396198A Expired - Lifetime JP3982090B2 (en) | 1998-12-22 | 1998-12-22 | Semiconductor ion sensor |
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| Country | Link |
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| JP (1) | JP3982090B2 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7112987B2 (en) * | 2003-06-06 | 2006-09-26 | Micronas Gmbh | Semiconductor sensor with a field-effect transistor |
| CN100334443C (en) * | 2003-06-02 | 2007-08-29 | 友达光电股份有限公司 | Ion induced field effect transistor and producing method thereof |
| US20100159461A1 (en) * | 2004-07-13 | 2010-06-24 | Dna Electronics Ltd. | Ion sensitive field effect transistors |
| CN114441611A (en) * | 2021-12-22 | 2022-05-06 | 天津大学 | Glucose sensor with wide dynamic measurement range based on organic field effect transistor |
-
1998
- 1998-12-22 JP JP36396198A patent/JP3982090B2/en not_active Expired - Lifetime
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100334443C (en) * | 2003-06-02 | 2007-08-29 | 友达光电股份有限公司 | Ion induced field effect transistor and producing method thereof |
| US7112987B2 (en) * | 2003-06-06 | 2006-09-26 | Micronas Gmbh | Semiconductor sensor with a field-effect transistor |
| US20100159461A1 (en) * | 2004-07-13 | 2010-06-24 | Dna Electronics Ltd. | Ion sensitive field effect transistors |
| CN114441611A (en) * | 2021-12-22 | 2022-05-06 | 天津大学 | Glucose sensor with wide dynamic measurement range based on organic field effect transistor |
| CN114441611B (en) * | 2021-12-22 | 2024-03-26 | 天津大学 | Wide dynamic measurement range glucose sensor based on organic field effect transistor |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3982090B2 (en) | 2007-09-26 |
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