JP5458702B2

JP5458702B2 - UV sensor

Info

Publication number: JP5458702B2
Application number: JP2009157376A
Authority: JP
Inventors: 和敬中村; 拓哉中里; 剛司林
Original assignee: Murata Manufacturing Co Ltd
Current assignee: Murata Manufacturing Co Ltd
Priority date: 2009-07-02
Filing date: 2009-07-02
Publication date: 2014-04-02
Anticipated expiration: 2029-07-02
Also published as: JP2011014710A

Description

本発明は、紫外線を検知する紫外線センサに関し、特に、紫外線を受光する部分に酸化物半導体を用いた紫外線センサに関する。 The present invention relates to an ultraviolet sensor that detects ultraviolet rays, and more particularly, to an ultraviolet sensor that uses an oxide semiconductor in a portion that receives ultraviolet rays.

従来の紫外線を検知する紫外線センサでは、紫外線を受光する部分に紫外線光電管が用いられていた。しかし、紫外線光電管は、非常に高い駆動電圧が必要であり、紫外線センサ自体が大型化するという問題点があった。近年、斯かる問題点を解消するために、紫外線を受光する部分に酸化物半導体を用いた紫外線センサが開発されている。 In a conventional ultraviolet sensor that detects ultraviolet rays, an ultraviolet photoelectric tube is used in a portion that receives ultraviolet rays. However, the ultraviolet phototube requires a very high driving voltage, and there is a problem that the ultraviolet sensor itself becomes large. In recent years, in order to solve such a problem, an ultraviolet sensor using an oxide semiconductor in a portion that receives ultraviolet rays has been developed.

例えば、特許文献１には、紫外線を受光する部分に酸化物半導体を用いた紫外線センサが開示されている。特許文献１に開示されている紫外線センサは、ＺｎＯを含む酸化物半導体で構成されたＺｎＯ層と、ＺｎＯがＮｉＯに固溶してなる酸化物半導体で構成された（Ｎｉ，Ｚｎ）Ｏ層と、ＺｎＯ層に電気的に接続される第１の端子電極と、（Ｎｉ，Ｚｎ）Ｏ層に電気的に接続される第２の端子電極とを備えている。特許文献１に開示されている紫外線センサでは、ＺｎＯ層と（Ｎｉ，Ｚｎ）Ｏ層との接合部に紫外線が当たった場合、光電効果により接合部に光電子が生じることで第１の端子電極と第２の端子電極との間の抵抗値が低下する。したがって、第１の端子電極と第２の端子電極との間の電圧（電流）値の変化によって紫外線を検知することができる。 For example, Patent Document 1 discloses an ultraviolet sensor using an oxide semiconductor in a portion that receives ultraviolet light. The ultraviolet sensor disclosed in Patent Document 1 includes a ZnO layer made of an oxide semiconductor containing ZnO, and a (Ni, Zn) O layer made of an oxide semiconductor in which ZnO is dissolved in NiO. , A first terminal electrode electrically connected to the ZnO layer, and a second terminal electrode electrically connected to the (Ni, Zn) O layer. In the ultraviolet sensor disclosed in Patent Document 1, when ultraviolet light hits the junction between the ZnO layer and the (Ni, Zn) O layer, photoelectrons are generated in the junction by the photoelectric effect, and the first terminal electrode and The resistance value between the second terminal electrode is lowered. Therefore, ultraviolet rays can be detected by a change in voltage (current) value between the first terminal electrode and the second terminal electrode.

特許第３９５２０７６号公報Japanese Patent No. 3952076

酸化物半導体は、温度により抵抗値が変化するという温度特性を有している。そのため、紫外線を受光する部分に酸化物半導体を用いた紫外線センサでは、使用される周辺環境の温度により酸化物半導体の抵抗値が変化し、測定する第１の端子電極と第２の端子電極との間の電圧（電流）値が変化する。したがって、酸化物半導体の温度特性に応じて、測定した第１の端子電極と第２の端子電極との間の電圧（電流）値を適正に補正しないと正しく紫外線を検知することができないという問題点があった。そこで、従来の紫外線センサでは、酸化物半導体の温度特性に応じて、測定した第１の端子電極と第２の端子電極との間の電圧（電流）値を、ＯＰアンプ等を用いて補正していた。 An oxide semiconductor has a temperature characteristic in which a resistance value changes with temperature. Therefore, in an ultraviolet sensor using an oxide semiconductor in a portion that receives ultraviolet light, the resistance value of the oxide semiconductor changes depending on the temperature of the surrounding environment used, and the first terminal electrode and the second terminal electrode to be measured The voltage (current) value during the period changes. Therefore, there is a problem in that ultraviolet rays cannot be correctly detected unless the measured voltage (current) value between the first terminal electrode and the second terminal electrode is appropriately corrected according to the temperature characteristics of the oxide semiconductor. There was a point. Therefore, in the conventional ultraviolet sensor, the measured voltage (current) value between the first terminal electrode and the second terminal electrode is corrected using an OP amplifier or the like according to the temperature characteristics of the oxide semiconductor. It was.

しかし、ＯＰアンプ等を用いて第１の端子電極と第２の端子電極との間の電圧（電流）値を補正する場合、ＯＰアンプ等を用いた補正回路の設計によっては、使用が予定される周辺環境の所定の温度範囲については適性に補正することができるものの、所定の温度範囲外については適正に補正することができない場合が生じるという問題点があった。また、従来の紫外線センサは、ＯＰアンプ等の製品バラツキにより、測定した第１の端子電極と第２の端子電極との間の電圧（電流）値の補正自体にもバラツキが生じるという問題点があった。さらに、従来の紫外線センサは、ＯＰアンプ等を用いた補正回路を備える必要があるため、製造コストが高くなるという問題点もあった。 However, when the voltage (current) value between the first terminal electrode and the second terminal electrode is corrected using an OP amplifier or the like, it is planned to be used depending on the design of the correction circuit using the OP amplifier or the like. Although the predetermined temperature range of the surrounding environment can be appropriately corrected, there is a problem that it may not be appropriately corrected outside the predetermined temperature range. In addition, the conventional ultraviolet sensor has a problem in that the correction of the measured voltage (current) value between the first terminal electrode and the second terminal electrode itself varies due to variations in the product such as the OP amplifier. there were. Furthermore, since the conventional ultraviolet sensor needs to include a correction circuit using an OP amplifier or the like, there is a problem that the manufacturing cost is increased.

本発明は、上記事情に鑑みてなされたものであり、製造コストが安く、酸化物半導体の温度特性に応じて電圧（電流）値を適正に補正することが可能な紫外線センサを提供することを目的とする。 The present invention has been made in view of the above circumstances, and provides an ultraviolet sensor capable of correcting a voltage (current) value appropriately according to temperature characteristics of an oxide semiconductor at a low manufacturing cost. Objective.

上記目的を達成するために第１発明に係る紫外線センサは、ＺｎＯがＮｉＯに固溶してなる酸化物半導体で構成された直方体形状の基板と、該基板内に形成された内部電極と、前記基板の第１面の一部に形成された、ＺｎＯからなる外部電極と、前記内部電極の一部が外部へ露出した前記基板の第２面に形成され、前記内部電極と接続された第１端子電極と、前記外部電極が形成された前記第１面及び前記第１端子電極が形成された第２面と異なる前記基板の第３面に形成された第２端子電極とを備え、前記第１端子電極及び前記第２端子電極は、前記基板の長手方向の両端面にそれぞれ形成されており、前記内部電極の一端は、前記第１端子電極に接続され、前記内部電極の他端は、前記第２端子電極に接続されておらず、前記外部電極は、前記第１端子電極及び前記第２端子電極に接続されておらず、前記基板の第１面から平面視した場合に、前記外部電極と前記第２端子電極との間隔よりも、前記内部電極の他端と前記第２端子電極との間隔の方が短く、前記外部電極と前記第２端子電極との間に印加する所定の電圧を、前記内部電極で分圧する。 In order to achieve the above object, an ultraviolet sensor according to a first invention includes a rectangular parallelepiped substrate made of an oxide semiconductor in which ZnO is dissolved in NiO, an internal electrode formed in the substrate, An external electrode made of ZnO formed on a part of the first surface of the substrate, and a first surface formed on the second surface of the substrate where a part of the internal electrode is exposed to the outside and connected to the internal electrode. A terminal electrode; and a second terminal electrode formed on a third surface of the substrate different from the first surface on which the external electrode is formed and the second surface on which the first terminal electrode is formed, The one terminal electrode and the second terminal electrode are respectively formed on both end surfaces of the substrate in the longitudinal direction, one end of the internal electrode is connected to the first terminal electrode, and the other end of the internal electrode is The external electrode is not connected to the second terminal electrode, Not connected to the first terminal electrode and the second terminal electrode, when viewed in plan from the first surface of the substrate, than the distance between the external electrode and the second terminal electrode, the inner electrode A distance between the other end and the second terminal electrode is shorter , and a predetermined voltage applied between the external electrode and the second terminal electrode is divided by the internal electrode.

また、第２発明に係る紫外線センサは、第１発明において、前記内部電極で分圧された、前記外部電極と前記内部電極との間の電圧及び／又は前記内部電極と前記第２端子電極との間の電圧を測定する。 The ultraviolet sensor according to a second aspect of the present invention is the ultraviolet sensor according to the first aspect, wherein the voltage between the external electrode and the internal electrode is divided by the internal electrode and / or the internal electrode and the second terminal electrode. Measure the voltage between.

また、第３発明に係る紫外線センサは、第１又は第２発明において、前記外部電極は、紫外線を透過する材料で形成してある。 In the ultraviolet sensor according to a third aspect of the present invention, in the first or second aspect , the external electrode is made of a material that transmits ultraviolet light.

また、第４発明に係る紫外線センサは、第１乃至第３発明のいずれか一つにおいて、前記外部電極と、前記第１端子電極及び前記第２端子電極との間の前記基板の前記第１面に形成された絶縁層を備える。 An ultraviolet sensor according to a fourth aspect of the present invention is the ultraviolet sensor according to any one of the first to third aspects, wherein the first electrode of the substrate between the external electrode and the first terminal electrode and the second terminal electrode is provided. An insulating layer is provided on the surface.

第１発明では、ＺｎＯがＮｉＯに固溶してなる酸化物半導体で構成された直方体形状の基板と、該基板内に形成された内部電極と、基板の第１面の一部に形成された、ＺｎＯからなる外部電極と、内部電極の一部が外部へ露出した基板の第２面に形成され、内部電極と接続された第１端子電極と、外部電極が形成された第１面及び第１端子電極が形成された第２面と異なる基板の第３面に形成された第２端子電極とを備える。第１端子電極及び第２端子電極は、基板の長手方向の両端面にそれぞれ形成されており、内部電極の一端は、第１端子電極に接続され、内部電極の他端は、第２端子電極に接続されておらず、外部電極は、第１端子電極及び第２端子電極に接続されておらず、基板の第１面から平面視した場合に、外部電極と第２端子電極との間隔よりも、内部電極の他端と第２端子電極との間隔の方が短い。外部電極と第２端子電極との間に印加する所定の電圧を、基板内に形成された内部電極で分圧することにより、使用される周辺環境の温度による外部電極と内部電極との間の酸化物半導体の抵抗値の変化と、内部電極と第２端子電極との間の酸化物半導体の抵抗値の変化とを相殺するので、酸化物半導体の温度特性に応じて適正に補正した電圧（電流）値を得ることができる。また、ＯＰアンプ等を用いた補正回路を備える必要がないため、製造コストを安くすることができる。 In the first invention, a rectangular parallelepiped substrate made of an oxide semiconductor in which ZnO is dissolved in NiO, an internal electrode formed in the substrate, and a part of the first surface of the substrate are formed. , An external electrode made of ZnO, a first terminal electrode connected to the internal electrode, formed on the second surface of the substrate, a part of the internal electrode being exposed to the outside, the first surface on which the external electrode is formed, and the first surface A second terminal electrode formed on a third surface of the substrate different from the second surface on which the one terminal electrode is formed. The first terminal electrode and the second terminal electrode are respectively formed on both end faces of the substrate in the longitudinal direction, one end of the internal electrode is connected to the first terminal electrode, and the other end of the internal electrode is the second terminal electrode. The external electrode is not connected to the first terminal electrode and the second terminal electrode, and when viewed in plan from the first surface of the substrate, the distance between the external electrode and the second terminal electrode In addition, the distance between the other end of the internal electrode and the second terminal electrode is shorter. By dividing a predetermined voltage applied between the external electrode and the second terminal electrode by the internal electrode formed in the substrate, oxidation between the external electrode and the internal electrode due to the temperature of the surrounding environment to be used is performed. Since the change in the resistance value of the physical semiconductor cancels out the change in the resistance value of the oxide semiconductor between the internal electrode and the second terminal electrode, the voltage (current) appropriately corrected according to the temperature characteristics of the oxide semiconductor ) Value can be obtained. Further, since it is not necessary to provide a correction circuit using an OP amplifier or the like, the manufacturing cost can be reduced.

第２発明では、外部電極と内部電極との間の電圧及び／又は内部電極と第２端子電極との間の電圧を測定することにより、基板と外部電極とが接する部分で生じる光電子により外部電極と内部電極との間の抵抗値が低下したことを検知することで、紫外線を検知することができる。 In the second invention, by measuring the voltage between the external electrode and the internal electrode and / or the voltage between the internal electrode and the second terminal electrode, the external electrode is generated by photoelectrons generated at the portion where the substrate and the external electrode are in contact with each other. UV light can be detected by detecting that the resistance value between the electrode and the internal electrode has decreased.

第３発明では、外部電極は、紫外線を透過する材料を用いて形成することにより、基板と外部電極とが接する部分で光電効果により光電子を効率よく生じさせることができる。 In the third invention, the external electrode is formed using a material that transmits ultraviolet rays, whereby photoelectrons can be efficiently generated by a photoelectric effect at a portion where the substrate and the external electrode are in contact with each other.

第４発明では、外部電極と、第１端子電極及び第２端子電極との間の基板の第１面に形成された絶縁層を備えることにより、外部電極と第１端子電極及び第２端子電極との間を流れるリーク電流を抑えることで、より広い周辺環境の温度範囲で酸化物半導体の温度特性に応じて適正に補正した電圧（電流）値を得ることができる。 In the fourth invention, the external electrode, the first terminal electrode, and the second terminal electrode are provided by including an insulating layer formed on the first surface of the substrate between the external electrode and the first terminal electrode and the second terminal electrode. By suppressing the leakage current flowing between the two, a voltage (current) value appropriately corrected according to the temperature characteristics of the oxide semiconductor can be obtained in a wider temperature range of the surrounding environment.

本発明に係る紫外線センサは、ＺｎＯがＮｉＯに固溶してなる酸化物半導体で構成された直方体形状の基板と、基板内に形成された内部電極と、基板の第１面の一部に形成された、ＺｎＯからなる外部電極と、内部電極の一部が外部へ露出した基板の第２面に形成され、内部電極と接続された第１端子電極と、外部電極が形成された第１面及び第１端子電極が形成された第２面と異なる基板の第３面に形成された第２端子電極とを備える。第１端子電極及び第２端子電極は、基板の長手方向の両端面にそれぞれ形成されており、内部電極の一端は、第１端子電極に接続され、内部電極の他端は、第２端子電極に接続されておらず、外部電極は、第１端子電極及び第２端子電極に接続されておらず、基板の第１面から平面視した場合に、外部電極と第２端子電極との間隔よりも、内部電極の他端と第２端子電極との間隔の方が短い。外部電極と第２端子電極との間に印加する所定の電圧を、内部電極で分圧することにより、使用される周辺環境の温度による外部電極と内部電極との間の酸化物半導体の抵抗値の変化と、内部電極と第２端子電極との間の酸化物半導体の抵抗値の変化とを相殺するので、酸化物半導体の温度特性に応じて適正に補正した電圧（電流）値を得ることができる。つまり、周辺環境の温度に依存することなく、紫外線を検知することができる。また、ＯＰアンプ等を用いた補正回路を備える必要がないため、製造コストを安くすることができる。 An ultraviolet sensor according to the present invention is formed on a part of a first surface of a substrate, a rectangular parallelepiped substrate made of an oxide semiconductor formed by dissolving ZnO in NiO, an internal electrode formed in the substrate, and the like. The first surface on which the external electrode made of ZnO, the first terminal electrode connected to the internal electrode, and the external electrode are formed on the second surface of the substrate where a part of the internal electrode is exposed to the outside. And a second terminal electrode formed on a third surface of the substrate different from the second surface on which the first terminal electrode is formed. The first terminal electrode and the second terminal electrode are respectively formed on both end faces of the substrate in the longitudinal direction, one end of the internal electrode is connected to the first terminal electrode, and the other end of the internal electrode is the second terminal electrode. The external electrode is not connected to the first terminal electrode and the second terminal electrode, and when viewed in plan from the first surface of the substrate, the distance between the external electrode and the second terminal electrode In addition, the distance between the other end of the internal electrode and the second terminal electrode is shorter. By dividing a predetermined voltage applied between the external electrode and the second terminal electrode by the internal electrode, the resistance value of the oxide semiconductor between the external electrode and the internal electrode due to the temperature of the surrounding environment to be used can be reduced. Since the change and the change in resistance value of the oxide semiconductor between the internal electrode and the second terminal electrode are canceled out, it is possible to obtain a voltage (current) value appropriately corrected according to the temperature characteristics of the oxide semiconductor. it can. That is, ultraviolet rays can be detected without depending on the temperature of the surrounding environment. Further, since it is not necessary to provide a correction circuit using an OP amplifier or the like, the manufacturing cost can be reduced.

本発明の実施の形態１に係る紫外線センサの構成を示す概略図である。It is the schematic which shows the structure of the ultraviolet sensor which concerns on Embodiment 1 of this invention. 本発明の実施の形態１に係る紫外線センサの基板を形成する方法を説明するための概略図である。It is the schematic for demonstrating the method to form the board | substrate of the ultraviolet sensor which concerns on Embodiment 1 of this invention. 本発明の実施の形態１に係る紫外線センサの回路構成を示す模式図である。It is a schematic diagram which shows the circuit structure of the ultraviolet sensor which concerns on Embodiment 1 of this invention. 本発明の実施の形態１に係る紫外線センサの回路図である。It is a circuit diagram of the ultraviolet sensor which concerns on Embodiment 1 of this invention. 本発明の実施の形態１に係る紫外線センサの周辺環境の温度による外部電極と内部電極との間及び内部電極と端子電極との間の抵抗の変化、外部電極と内部電極との間の電圧の変化を示すグラフである。The change in resistance between the external electrode and the internal electrode and the internal electrode and the terminal electrode due to the temperature of the surrounding environment of the ultraviolet sensor according to Embodiment 1 of the present invention, the voltage between the external electrode and the internal electrode It is a graph which shows a change. 本発明の実施の形態１に係る紫外線センサの周辺環境の温度による外部電極と内部電極との間の電圧の変化を示すグラフである。It is a graph which shows the change of the voltage between an external electrode and an internal electrode by the temperature of the surrounding environment of the ultraviolet sensor which concerns on Embodiment 1 of this invention. 本発明の実施の形態２に係る紫外線センサの構成を示す概略図である。It is the schematic which shows the structure of the ultraviolet sensor which concerns on Embodiment 2 of this invention. 本発明の実施の形態２に係る紫外線センサの周辺環境の温度による外部電極と内部電極との間の電圧の変化を示すグラフである。It is a graph which shows the change of the voltage between an external electrode and an internal electrode by the temperature of the surrounding environment of the ultraviolet sensor which concerns on Embodiment 2 of this invention. 従来の紫外線センサの回路構成を示す模式図である。It is a schematic diagram which shows the circuit structure of the conventional ultraviolet sensor. 従来の紫外線センサの回路図である。It is a circuit diagram of the conventional ultraviolet sensor. 抵抗を追加した従来の紫外線センサの回路図である。It is a circuit diagram of the conventional ultraviolet sensor which added resistance.

以下、本発明の実施の形態における紫外線センサについて、図面を用いて具体的に説明する。以下の実施の形態は、特許請求の範囲に記載された発明を限定するものではなく、実施の形態の中で説明されている特徴的事項の組み合わせの全てが解決手段の必須事項であるとは限らないことは言うまでもない。 Hereinafter, an ultraviolet sensor according to an embodiment of the present invention will be specifically described with reference to the drawings. The following embodiments do not limit the invention described in the claims, and all combinations of characteristic items described in the embodiments are essential to the solution. It goes without saying that it is not limited.

（実施の形態１）
図１は、本発明の実施の形態１に係る紫外線センサの構成を示す概略図である。図１（ａ）は、本発明の実施の形態１に係る紫外線センサの平面図である。図１（ｂ）は、図１（ａ）に示す紫外線センサのＡ−Ａ断面図である。図１（ａ）に示すように、紫外線センサ１は、酸化物半導体で構成された直方体形状の基板２のそれぞれ異なる面に形成された、外部電極３、端子電極４、端子電極５（第１端子電極）、端子電極６（第２端子電極）を備えている。外部電極３は、端子電極４と接続しているが、端子電極５及び端子電極６とは接続していない。端子電極４は、基板２の、外部電極３が形成されている面（第１面）に対して垂直な面に形成されている。端子電極５、６は、基板２の長手方向にある両端面（第２面、第３面）にそれぞれ形成されている。図１（ｂ）に示すように、紫外線センサ１は、基板２内に、外部電極３と平行に形成された内部電極７を備えている。端子電極５は、基板２の端面（第２面）から外部へ露出した内部電極７の一部と接続している。 (Embodiment 1)
FIG. 1 is a schematic diagram showing a configuration of an ultraviolet sensor according to Embodiment 1 of the present invention. Fig.1 (a) is a top view of the ultraviolet sensor which concerns on Embodiment 1 of this invention. FIG.1 (b) is AA sectional drawing of the ultraviolet sensor shown to Fig.1 (a). As shown in FIG. 1A, the ultraviolet sensor 1 includes an external electrode 3, a terminal electrode 4, and a terminal electrode 5 (first electrodes) formed on different surfaces of a rectangular parallelepiped substrate 2 made of an oxide semiconductor. Terminal electrode) and a terminal electrode 6 (second terminal electrode). The external electrode 3 is connected to the terminal electrode 4 but is not connected to the terminal electrode 5 and the terminal electrode 6. The terminal electrode 4 is formed on a surface of the substrate 2 that is perpendicular to the surface (first surface) on which the external electrode 3 is formed. The terminal electrodes 5 and 6 are respectively formed on both end surfaces (second surface and third surface) in the longitudinal direction of the substrate 2. As shown in FIG. 1B, the ultraviolet sensor 1 includes an internal electrode 7 formed in a substrate 2 in parallel with the external electrode 3. The terminal electrode 5 is connected to a part of the internal electrode 7 exposed to the outside from the end surface (second surface) of the substrate 2.

基板２を構成する酸化物半導体は、２０〜４０モル％のＺｎＯがＮｉＯに固溶してなる（Ｎｉ，Ｚｎ）Ｏの酸化物半導体である。ただし、基板２を構成する酸化物半導体は、（Ｎｉ，Ｚｎ）Ｏに限定されるものではなく、ＮｉＯ、ＺｎＯ、ＴｉＯ₂等でも良い。なお、紫外線センサ１は、基板２を構成する酸化物半導体のバンドギャップ値によって検知することができる紫外線の波長領域が異なる。例えば、基板２を構成する酸化物半導体がＮｉＯである紫外線センサ１は、波長が２８０ｎｍ以下の紫外線を検知することができ、酸化物半導体がＺｎＯである紫外線センサ１は、波長が３８０ｎｍ以下の紫外線を検知することができる。また、基板２を構成する酸化物半導体が（Ｎｉ，Ｚｎ）Ｏである紫外線センサ１は、波長が４００ｎｍ以下の紫外線を検知することができる。 The oxide semiconductor constituting the substrate 2 is a (Ni, Zn) O oxide semiconductor in which 20 to 40 mol% of ZnO is dissolved in NiO. However, the oxide semiconductor constituting the substrate 2 is not limited to (Ni, Zn) O, and may be NiO, ZnO, TiO ₂ or the like. The ultraviolet sensor 1 differs in the wavelength range of ultraviolet rays that can be detected depending on the band gap value of the oxide semiconductor constituting the substrate 2. For example, the ultraviolet sensor 1 in which the oxide semiconductor constituting the substrate 2 is NiO can detect ultraviolet light having a wavelength of 280 nm or less, and the ultraviolet sensor 1 in which the oxide semiconductor is ZnO has ultraviolet light having a wavelength of 380 nm or less. Can be detected. Moreover, the ultraviolet sensor 1 whose oxide semiconductor which comprises the board | substrate 2 is (Ni, Zn) O can detect the ultraviolet-ray whose wavelength is 400 nm or less.

ここで、基板２を形成する方法について、以下に説明する。図２は、本発明の実施の形態１に係る紫外線センサ１の基板２を形成する方法を説明するための概略図である。まず、（Ｎｉ，Ｚｎ）Ｏの酸化物半導体からなるグリーンシート２１を形成する。グリーンシート２１の形成処理は、ＮｉＯとＺｎＯとの割合が６５モル％と３５モル％となるように、原料のＮｉＯ及びＺｎＯの無機粉末を秤量し、秤量した無機粉末に純水を加え、ＰＳＺ（安定化ジルコニア）ビーズをメディア（粉砕用ボール（球石））として、ボールミルにて平均粒径０．５μｍ以下となるように混合粉砕する。さらに、混合粉砕によりスラリーとなった無機粉末を、脱水乾燥し、５０μｍ程度の粒径の粉末に造粒した後、１２００℃の温度で２時間仮焼する。仮焼した無機粉末に、純水を加え、ＰＳＺビーズをメディアとしてボールミルにて平均粒径０．５μｍになるまで混合粉砕する。混合粉砕した無機粉末は、脱水乾燥した後、有機溶剤及び分散剤を加えて混合し、さらにバインダ及び可塑剤を加えスラリーとし、ドクターブレード法を用いて、厚み１０μｍのシートに成形する。成形したシートを板状にカットし、複数枚のグリーンシート２１として形成する。 Here, a method for forming the substrate 2 will be described below. FIG. 2 is a schematic diagram for explaining a method of forming the substrate 2 of the ultraviolet sensor 1 according to Embodiment 1 of the present invention. First, the green sheet 21 made of an (Ni, Zn) O oxide semiconductor is formed. The green sheet 21 is formed by weighing the raw material NiO and ZnO inorganic powder so that the ratio of NiO and ZnO is 65 mol% and 35 mol%, adding pure water to the weighed inorganic powder, The (stabilized zirconia) beads are used as media (balls for crushing (spheroids)) and mixed and ground by a ball mill so that the average particle size is 0.5 μm or less. Further, the inorganic powder that has become a slurry by mixing and pulverizing is dehydrated and dried, granulated to a powder having a particle size of about 50 μm, and then calcined at a temperature of 1200 ° C. for 2 hours. Pure water is added to the calcined inorganic powder and mixed and pulverized with a ball mill using PSZ beads as a medium until the average particle size becomes 0.5 μm. The mixed and pulverized inorganic powder is dehydrated and dried, mixed with an organic solvent and a dispersant, further added with a binder and a plasticizer to form a slurry, and formed into a sheet having a thickness of 10 μm using a doctor blade method. The formed sheet is cut into a plate shape and formed as a plurality of green sheets 21.

次に、形成した複数枚のグリーンシート２１のいずれか１枚に、Ｐｄペーストをスクリーン印刷し、６０℃の温度で１時間乾燥して内部電極７を形成する。図２に示すように、内部電極７を形成したグリーンシート２１は、内部電極７を形成した面側に他のグリーンシート２１を１枚積層し、反対の面側に他のグリーンシート２１を複数枚積層する。なお、積層したグリーンシート２１の厚みが０．２ｍｍとなるように、積層するグリーンシート２１の枚数を２０枚とする。 Next, the Pd paste is screen-printed on any one of the formed green sheets 21 and dried at a temperature of 60 ° C. for 1 hour to form the internal electrodes 7. As shown in FIG. 2, in the green sheet 21 on which the internal electrode 7 is formed, another green sheet 21 is laminated on the surface side on which the internal electrode 7 is formed, and a plurality of other green sheets 21 are formed on the opposite surface side. Laminate the sheets. The number of stacked green sheets 21 is 20 so that the thickness of the stacked green sheets 21 is 0.2 mm.

次に、積層したグリーンシート２１を、金型に入れて２０ＭＰａの圧力で圧着した後、所定の形状に合わせてカットする。カットしたグリーンシート２１は、３００℃の温度でゆっくりと、十分に脱脂した後、１２５０℃の温度で５時間焼成することにより、基板２を形成する。なお、積層したグリーンシート２１を、後述するＺｎＯシートに載せて焼成することで、焼成中に揮発成分であるＺｎＯが揮発するのを抑制することもできる。 Next, the stacked green sheets 21 are put into a mold and pressed with a pressure of 20 MPa, and then cut according to a predetermined shape. The cut green sheet 21 is sufficiently degreased slowly at a temperature of 300 ° C. and then fired at a temperature of 1250 ° C. for 5 hours to form the substrate 2. In addition, it can also suppress that ZnO which is a volatile component volatilizes during baking by mounting and laminating | stacking the laminated | stacked green sheet 21 on the ZnO sheet mentioned later.

形成した基板２は、３．２ｍｍ×１．６ｍｍ×０．２ｍｍの直方体形状となる。さらに、基板２は、直径が３ｍｍのアルミナビーズとともに塩化ビニル製のポットに入れ、遊星ミルを用いて端面に丸みを形成する。基板２の端面に丸みを形成することで、基板２の端面から外部へ露出した内部電極７の一部と端子電極５とを容易に接続することができる。 The formed substrate 2 has a rectangular parallelepiped shape of 3.2 mm × 1.6 mm × 0.2 mm. Further, the substrate 2 is put into a vinyl chloride pot together with alumina beads having a diameter of 3 mm, and the end surface is rounded using a planetary mill. By forming roundness on the end surface of the substrate 2, a part of the internal electrode 7 exposed to the outside from the end surface of the substrate 2 and the terminal electrode 5 can be easily connected.

図１に戻って、外部電極３は、スパッタ法によって、基板２の一面にＺｎＯ層を成膜することにより形成されている。ＺｎＯ層の厚みは、約０．５μｍである。また、外部電極３は、端子電極４と接続しているが、端子電極５、６とは接続していない。なお、外部電極３を形成する材料は、特にＺｎＯに限定されるものではなく、紫外線を透過する材料であればＩＴＯ、ＴｉＯ₂、Ａｕ−Ｔｉ合金、ＰＥＤＯＴ（ポリエチレンジオキシチオフェン）：ＰＳＳ（ポリスチレンスルホン酸）等であっても良い。また、外部電極３の形成方法は、特にスパッタ法に限定されるものではなく、構成する材料によって蒸着法、塗布法等を用いても良い。 Returning to FIG. 1, the external electrode 3 is formed by forming a ZnO layer on one surface of the substrate 2 by sputtering. The thickness of the ZnO layer is about 0.5 μm. The external electrode 3 is connected to the terminal electrode 4, but is not connected to the terminal electrodes 5 and 6. The material for forming the external electrode 3 is not particularly limited to ZnO, and may be ITO, TiO ₂ , Au—Ti alloy, PEDOT (polyethylenedioxythiophene): PSS (polystyrene) as long as it is a material that transmits ultraviolet rays. Sulfonic acid) or the like. Moreover, the formation method of the external electrode 3 is not particularly limited to the sputtering method, and a vapor deposition method, a coating method, or the like may be used depending on the constituent material.

ＺｎＯ層を成膜するスパッタ法に用いるスパッタターゲットを形成する処理について、以下に説明する。まず、ＺｎとＧａとのモル比が９５：５となるように、ＺｎＯ及びＧａ₂Ｏ₃の粉末を秤量し、秤量した粉末に純水を加え、ＰＳＺビーズをメディアとしてボールミルにて平均粒径０．５μｍ以下となるように混合粉砕する。さらに、混合粉砕によりスラリーとなった粉末を、脱水乾燥し、５０μｍ程度の粒径の粉末に造粒した後、１２００℃の温度で２時間仮焼する。仮焼した粉末に、純水を加え、ＰＳＺビーズをメディアとしてボールミルにて平均粒径０．５μｍになるまで混合粉砕する。混合粉砕した粉末を、脱水乾燥した後、有機溶剤及び分散剤を加えて混合し、さらにバインダ及び可塑剤を加えスラリーとし、ドクターブレード法を用いて、厚み２０μｍのシートに成形する。成形したシートを板状にカットし、複数枚のＺｎＯシートとして形成する。形成したＺｎＯシートを、厚みが２０ｍｍとなるように、複数枚積層する。積層したＺｎＯシートは、２５０ＭＰａの圧力で５分間圧着した後、十分に脱脂して、１２００℃の温度で１時間焼成することでスパッタターゲットを形成する。 A process for forming a sputtering target used in a sputtering method for forming a ZnO layer will be described below. First, ZnO and Ga ₂ O ₃ powders are weighed so that the molar ratio of Zn to Ga is 95: 5, pure water is added to the weighed powders, and the average particle diameter is measured with a ball mill using PSZ beads as a medium. Mix and pulverize to 0.5 μm or less. Further, the powder that has become a slurry by mixing and pulverizing is dehydrated and dried, granulated into a powder having a particle size of about 50 μm, and calcined at a temperature of 1200 ° C. for 2 hours. Pure water is added to the calcined powder, and the mixture is pulverized using a PSZ bead as a medium to an average particle size of 0.5 μm using a ball mill. The mixed and pulverized powder is dehydrated and dried, mixed with an organic solvent and a dispersant, further added with a binder and a plasticizer to form a slurry, and formed into a sheet having a thickness of 20 μm using a doctor blade method. The formed sheet is cut into a plate shape and formed as a plurality of ZnO sheets. A plurality of the formed ZnO sheets are laminated so that the thickness becomes 20 mm. The laminated ZnO sheets are pressure-bonded at a pressure of 250 MPa for 5 minutes, sufficiently degreased, and fired at a temperature of 1200 ° C. for 1 hour to form a sputtering target.

図１（ａ）に戻って、端子電極４は、基板２の、外部電極３が形成されている面（第１面）に対して垂直な面にＡｇペーストを塗布して、８００℃の温度で１０分間焼成して形成する。なお、端子電極４は、外部電極３が形成されている基板２の面（第１面）に形成した一部が外部電極３と接続している。端子電極５は、内部電極７の一部が外部へ露出した基板２の面（第２面）にＡｇペーストを塗布して、８００℃の温度で１０分間焼成して形成する。端子電極６は、端子電極５が形成してある基板２の面（第２面）と対向する面（第３面）にＡｇペーストを塗布して、８００℃の温度で１０分間焼成して形成する。さらに、端子電極４、５、６には、Ｎｉ、Ｓｎの順に電解メッキを施している。 Referring back to FIG. 1A, the terminal electrode 4 has a temperature of 800 ° C. applied to the surface of the substrate 2 perpendicular to the surface (first surface) on which the external electrode 3 is formed. And baked for 10 minutes. Note that a part of the terminal electrode 4 formed on the surface (first surface) of the substrate 2 on which the external electrode 3 is formed is connected to the external electrode 3. The terminal electrode 5 is formed by applying an Ag paste to the surface (second surface) of the substrate 2 where a part of the internal electrode 7 is exposed to the outside, and baking it at a temperature of 800 ° C. for 10 minutes. The terminal electrode 6 is formed by applying an Ag paste to a surface (third surface) opposite to the surface (second surface) of the substrate 2 on which the terminal electrode 5 is formed, and baking it at a temperature of 800 ° C. for 10 minutes. To do. Further, the terminal electrodes 4, 5, 6 are subjected to electrolytic plating in the order of Ni and Sn.

次に、本実施の形態１に係る紫外線センサ１の動作について、以下に説明する。図３は、本発明の実施の形態１に係る紫外線センサ１の回路構成を示す模式図である。図４は、本発明の実施の形態１に係る紫外線センサ１の回路図である。図３に示すように、紫外線センサ１は、電源１１のプラス側が端子電極４に、電源１１のマイナス側が端子電極６にそれぞれ接続されている。 Next, operation | movement of the ultraviolet sensor 1 which concerns on this Embodiment 1 is demonstrated below. FIG. 3 is a schematic diagram showing a circuit configuration of the ultraviolet sensor 1 according to Embodiment 1 of the present invention. FIG. 4 is a circuit diagram of the ultraviolet sensor 1 according to Embodiment 1 of the present invention. As shown in FIG. 3, in the ultraviolet sensor 1, the positive side of the power source 11 is connected to the terminal electrode 4, and the negative side of the power source 11 is connected to the terminal electrode 6.

紫外線センサ１は、ＺｎＯ層の外部電極３と酸化物半導体（（Ｎｉ，Ｚｎ）Ｏ）の基板２とが接する部分に紫外線が当たった場合、光電効果により当該部分に光電子が生じることで外部電極３と内部電極７との間の抵抗値が低下し、測定する外部電極３と内部電極７との間の電圧（電流）値が変化する。したがって、紫外線センサ１は、外部電極３と内部電極７との間の電圧（電流）の値を測定することで紫外線を検知することができる。紫外線センサ１は、電源１１により端子電極４と端子電極６との間にバイアス電圧を印加した場合、端子電極４から外部電極３、内部電極７、端子電極６へ電流が流れることになるので、外部電極３と内部電極７との間に抵抗３１、内部電極７と端子電極６との間に抵抗３２を設けた回路構成とみなすことができる。 When the ultraviolet sensor 1 hits a portion where the external electrode 3 of the ZnO layer and the oxide semiconductor ((Ni, Zn) O) substrate 2 are in contact with each other, photoelectrons are generated in the portion due to the photoelectric effect. The resistance value between the external electrode 3 and the internal electrode 7 decreases, and the voltage (current) value between the external electrode 3 and the internal electrode 7 to be measured changes. Therefore, the ultraviolet sensor 1 can detect ultraviolet rays by measuring the voltage (current) value between the external electrode 3 and the internal electrode 7. In the ultraviolet sensor 1, when a bias voltage is applied between the terminal electrode 4 and the terminal electrode 6 by the power supply 11, a current flows from the terminal electrode 4 to the external electrode 3, the internal electrode 7, and the terminal electrode 6. It can be regarded as a circuit configuration in which a resistor 31 is provided between the external electrode 3 and the internal electrode 7 and a resistor 32 is provided between the internal electrode 7 and the terminal electrode 6.

つまり、紫外線センサ１は、図４に示すように、端子電極４（外部電極３）と端子電極６との間に、抵抗３１、３２を直列に接続した回路とみなすことができるため、端子電極４と端子電極６との間（外部電極３と端子電極６との間）に印加するバイアス電圧は、抵抗３１、３２により外部電極３と内部電極７との間の電圧、及び内部電極７と端子電極６との間の電圧に分圧される。なお、紫外線４０が当たった場合、ＺｎＯ層の外部電極３と酸化物半導体（（Ｎｉ，Ｚｎ）Ｏ）の基板２とが接する部分に生じた光電子により、抵抗３１の抵抗値は低下するが、抵抗３２の抵抗値は変化しない。 That is, the ultraviolet sensor 1 can be regarded as a circuit in which resistors 31 and 32 are connected in series between the terminal electrode 4 (external electrode 3) and the terminal electrode 6 as shown in FIG. 4 and the terminal electrode 6 (between the external electrode 3 and the terminal electrode 6) are bias voltages applied between the external electrode 3 and the internal electrode 7 by the resistors 31 and 32, and the internal electrode 7 The voltage is divided between the terminal electrodes 6. In addition, when the ultraviolet ray 40 hits, the resistance value of the resistor 31 decreases due to photoelectrons generated in the portion where the external electrode 3 of the ZnO layer and the substrate 2 of the oxide semiconductor ((Ni, Zn) O) are in contact with each other. The resistance value of the resistor 32 does not change.

ここで、従来の紫外線センサの回路構成について説明する。図９は、従来の紫外線センサの回路構成を示す模式図である。図１０は、従来の紫外線センサの回路図である。図９に示すように、従来の紫外線センサ１０１は、電源１１１のプラス側が外部電極１０３に接続された端子電極１０６に、電源１１１のマイナス側が内部電極１０７に接続された端子電極１０５にそれぞれ接続されている。 Here, a circuit configuration of a conventional ultraviolet sensor will be described. FIG. 9 is a schematic diagram showing a circuit configuration of a conventional ultraviolet sensor. FIG. 10 is a circuit diagram of a conventional ultraviolet sensor. As shown in FIG. 9, the conventional ultraviolet sensor 101 is connected to the terminal electrode 106 connected to the external electrode 103 on the positive side of the power supply 111 and to the terminal electrode 105 connected to the internal electrode 107 on the negative side of the power supply 111. ing.

従来の紫外線センサ１０１も、ＺｎＯ層の外部電極１０３と酸化物半導体（（Ｎｉ，Ｚｎ）Ｏ）の基板１０２とが接する部分に紫外線が当たった場合、光電効果により当該部分に光電子が生じることで外部電極１０３と内部電極１０７との間の抵抗値が低下する。したがって、従来の紫外線センサ１０１は、外部電極１０３と内部電極１０７との間の電流値を測定することで紫外線を検知することができる。従来の紫外線センサ１０１は、電源１１１により端子電極１０６と端子電極１０５との間にバイアス電圧を印加した場合、端子電極１０５から内部電極１０７、外部電極１０３、端子電極１０６へ電流が流れることになるので、外部電極１０３と内部電極１０７との間に抵抗１３１を設けた回路構成とみなすことができる。 In the conventional ultraviolet sensor 101, when ultraviolet light hits a portion where the external electrode 103 of the ZnO layer and the oxide semiconductor ((Ni, Zn) O) substrate 102 are in contact with each other, photoelectrons are generated in the portion due to the photoelectric effect. The resistance value between the external electrode 103 and the internal electrode 107 decreases. Therefore, the conventional ultraviolet sensor 101 can detect ultraviolet rays by measuring the current value between the external electrode 103 and the internal electrode 107. In the conventional ultraviolet sensor 101, when a bias voltage is applied between the terminal electrode 106 and the terminal electrode 105 by the power source 111, a current flows from the terminal electrode 105 to the internal electrode 107, the external electrode 103, and the terminal electrode 106. Therefore, it can be regarded as a circuit configuration in which the resistor 131 is provided between the external electrode 103 and the internal electrode 107.

つまり、従来の紫外線センサ１０１は、図１０に示すように、端子電極１０６と端子電極１０５との間に抵抗１３１を設けた回路とみなすことができるため、端子電極１０６と端子電極１０５との間に印加するバイアス電圧は、抵抗１３１に印加される。なお、従来の紫外線センサ１０１も、紫外線４０が当たった場合、ＺｎＯ層の外部電極１０３と酸化物半導体（（Ｎｉ，Ｚｎ）Ｏ）の基板１０２とが接する部分に生じた光電子により、抵抗１３１の抵抗値が低下し、端子電極１０５と端子電極１０６との間の電流値の変化によって紫外線を検知することができる。 That is, the conventional ultraviolet sensor 101 can be regarded as a circuit in which a resistor 131 is provided between the terminal electrode 106 and the terminal electrode 105 as shown in FIG. The bias voltage applied to is applied to the resistor 131. Note that the conventional ultraviolet sensor 101 also has a resistance 131 due to photoelectrons generated in a portion where the external electrode 103 of the ZnO layer and the oxide semiconductor ((Ni, Zn) O) substrate 102 are in contact with each other when the ultraviolet ray 40 is irradiated. The resistance value decreases, and ultraviolet rays can be detected by a change in the current value between the terminal electrode 105 and the terminal electrode 106.

本実施の形態１に係る紫外線センサ１の回路は、図４に示す回路図と図１０に示す回路図とを比較することで分かるように、従来の紫外線センサ１０１の回路に、内部電極７と端子電極６との間に抵抗３２を追加してある。追加した抵抗３２は、外部電極３と基板２とが接する部分に生じる光電子の影響を受けないが、図３に示すように基板２内に設けてあるので、抵抗３１と同じように酸化物半導体の温度特性の影響を受ける。 As can be seen by comparing the circuit diagram shown in FIG. 4 with the circuit diagram shown in FIG. 10, the circuit of the ultraviolet sensor 1 according to the first embodiment includes the internal electrode 7 and the circuit of the conventional ultraviolet sensor 101. A resistor 32 is added between the terminal electrode 6. The added resistor 32 is not affected by the photoelectrons generated at the portion where the external electrode 3 and the substrate 2 are in contact with each other, but is provided in the substrate 2 as shown in FIG. Affected by the temperature characteristics of

また、基板２は、３．２ｍｍ×１．６ｍｍ×０．２ｍｍ程度の大きさであるため、紫外線センサ１を使用する周辺環境の温度によって、抵抗３１の温度と抵抗３２の温度との間に差は生じないものと考えられる。したがって、周辺環境の温度による抵抗３２の抵抗値の変化は、抵抗３１の抵抗値の変化と略同じになるため、紫外線センサ１は、外部電極３と端子電極６との間に印加するバイアス電圧を、抵抗３１と抵抗３２とにより外部電極３と内部電極７との間の電圧、及び内部電極７と端子電極６との間の電圧に分圧することにより、抵抗３１の抵抗値の変化と抵抗３２の抵抗値の変化とを相殺するので、酸化物半導体の温度特性に応じて補正した外部電極３と内部電極７との間の電圧値を得ることができる。 Moreover, since the board | substrate 2 is a magnitude | size of about 3.2 mm x 1.6 mm x 0.2 mm, depending on the temperature of the surrounding environment where the ultraviolet sensor 1 is used, it is between the temperature of the resistor 31 and the temperature of the resistor 32. It is considered that there will be no difference. Therefore, since the change in the resistance value of the resistor 32 due to the temperature of the surrounding environment is substantially the same as the change in the resistance value of the resistor 31, the ultraviolet sensor 1 applies a bias voltage applied between the external electrode 3 and the terminal electrode 6. Is divided into a voltage between the external electrode 3 and the internal electrode 7 and a voltage between the internal electrode 7 and the terminal electrode 6 by the resistor 31 and the resistor 32, thereby changing the resistance value and resistance of the resistor 31. Therefore, the voltage value between the external electrode 3 and the internal electrode 7 corrected according to the temperature characteristics of the oxide semiconductor can be obtained.

図５は、本発明の実施の形態１に係る紫外線センサ１の周辺環境の温度による外部電極３と内部電極７との間及び内部電極７と端子電極６との間の抵抗３１、３２の変化、外部電極３と内部電極７との間の電圧の変化を示すグラフである。特に、図５（ａ）は、周辺環境の温度による外部電極３と内部電極７との間の抵抗３１の変化を示すグラフである。図５（ｂ）は、周辺環境の温度による内部電極７と端子電極６との間の抵抗３２の変化を示すグラフである。図５（ｃ）は、周辺環境の温度による外部電極３と内部電極７との間の電圧の変化を示すグラフである。図５に示すように、抵抗３１及び抵抗３２は、周辺環境の温度が高くなるにつれて抵抗値が低下する。周辺環境の温度による抵抗３１の抵抗値の変化と、抵抗３２の抵抗値の変化とは略同じであるため、端子電極４と端子電極６との間に印加するバイアス電圧を抵抗３１と抵抗３２とで分圧した外部電極３と内部電極７との間の電圧は、周辺環境の温度による変化はなく略一定となる。従って、紫外線センサ１は、外部電極３と内部電極７との間の電圧を測定することで、酸化物半導体の温度特性に応じて適正に補正した電圧値を得ることができ、紫外線を検知することができる。なお、内部電極７と端子電極６との間の電圧を測定すれば、外部電極３と内部電極７との間の電圧を求めることができるので、測定する電圧は、特に外部電極３と内部電極７との間の電圧に限定されるものではなく、外部電極３と内部電極７との間の電圧及び／又は内部電極７と端子電極６との間の電圧を測定しても良い。 FIG. 5 shows changes in resistances 31 and 32 between the external electrode 3 and the internal electrode 7 and between the internal electrode 7 and the terminal electrode 6 depending on the temperature of the surrounding environment of the ultraviolet sensor 1 according to the first embodiment of the present invention. 4 is a graph showing a change in voltage between the external electrode 3 and the internal electrode 7. In particular, FIG. 5A is a graph showing a change in the resistance 31 between the external electrode 3 and the internal electrode 7 due to the temperature of the surrounding environment. FIG. 5B is a graph showing a change in the resistance 32 between the internal electrode 7 and the terminal electrode 6 due to the temperature of the surrounding environment. FIG. 5C is a graph showing a change in voltage between the external electrode 3 and the internal electrode 7 due to the temperature of the surrounding environment. As shown in FIG. 5, the resistance values of the resistor 31 and the resistor 32 decrease as the temperature of the surrounding environment increases. The change in the resistance value of the resistor 31 due to the temperature of the surrounding environment and the change in the resistance value of the resistor 32 are substantially the same. The voltage between the external electrode 3 and the internal electrode 7 divided by the above is substantially constant without change due to the temperature of the surrounding environment. Therefore, the ultraviolet sensor 1 can obtain a voltage value appropriately corrected according to the temperature characteristics of the oxide semiconductor by measuring the voltage between the external electrode 3 and the internal electrode 7, and detects ultraviolet light. be able to. Note that if the voltage between the internal electrode 7 and the terminal electrode 6 is measured, the voltage between the external electrode 3 and the internal electrode 7 can be obtained. The voltage between the external electrode 3 and the internal electrode 7 and / or the voltage between the internal electrode 7 and the terminal electrode 6 may be measured.

図６は、本発明の実施の形態１に係る紫外線センサ１の周辺環境の温度による外部電極３と内部電極７との間の電圧の変化を示すグラフである。図６は、紫外線センサ１に紫外線が当たらない状態で、周辺環境の温度が０℃から８０℃まで変化した場合の外部電極３と内部電極７との間の電圧の変化を示している。ここで、説明を簡単にするために、紫外線センサ１は、紫外線が当たらないときの抵抗３１と抵抗３２の抵抗値が同じになるように構成し、端子電極４と端子電極６との間に印加するバイアス電圧を３．０Ｖとする。紫外線が当たらない場合、外部電極３と内部電極７との間の電圧は約１．５Ｖになる。紫外線センサ１は、端子電極４と端子電極６との間に印加するバイアス電圧を内部電極７で分圧しているので、周辺環境の温度が変化しても、外部電極３と内部電極７との間の電圧は略一定となる。ただし、周辺環境の温度が５０℃以上になると外部電極３と内部電極７（端子電極５）との間の抵抗値が低下するので、外部電極３と内部電極７との間の電圧が少し低下している。例えば、周辺環境の温度が０℃の時、波長が３７０ｎｍ、放射強度１ｍＷ／ｃｍ²の紫外線を紫外線センサ１に当てると、抵抗３１の抵抗値が低下し、外部電極３と内部電極７との間の電圧は約１．０Ｖまで低下し、紫外線を検知することができる。紫外線が当たったことにより低下した電圧は、周辺環境の温度が０℃から５０℃まで変化しても、約１．０Ｖのままで略一定となるので、同様に紫外線を検知することができる。 FIG. 6 is a graph showing a change in voltage between the external electrode 3 and the internal electrode 7 due to the temperature of the surrounding environment of the ultraviolet sensor 1 according to Embodiment 1 of the present invention. FIG. 6 shows a change in voltage between the external electrode 3 and the internal electrode 7 when the temperature of the surrounding environment changes from 0 ° C. to 80 ° C. in a state where the ultraviolet sensor 1 is not exposed to ultraviolet rays. Here, in order to simplify the explanation, the ultraviolet sensor 1 is configured so that the resistance values of the resistor 31 and the resistor 32 when the ultraviolet rays are not applied are the same, and between the terminal electrode 4 and the terminal electrode 6. The bias voltage to be applied is set to 3.0V. When ultraviolet rays do not hit, the voltage between the external electrode 3 and the internal electrode 7 is about 1.5V. Since the ultraviolet sensor 1 divides the bias voltage applied between the terminal electrode 4 and the terminal electrode 6 by the internal electrode 7, even if the temperature of the surrounding environment changes, the external electrode 3 and the internal electrode 7 The voltage between them is substantially constant. However, since the resistance value between the external electrode 3 and the internal electrode 7 (terminal electrode 5) decreases when the temperature of the surrounding environment becomes 50 ° C. or higher, the voltage between the external electrode 3 and the internal electrode 7 slightly decreases. doing. For example, when the temperature of the surrounding environment is 0 ° C., when ultraviolet light having a wavelength of 370 nm and a radiation intensity of 1 mW / cm ² is applied to the ultraviolet sensor 1, the resistance value of the resistor 31 decreases, and the external electrode 3 and the internal electrode 7 The voltage between them decreases to about 1.0 V, and ultraviolet rays can be detected. Since the voltage that has decreased due to exposure to ultraviolet rays remains substantially constant at about 1.0 V even when the temperature of the surrounding environment changes from 0 ° C. to 50 ° C., the ultraviolet rays can be detected in the same manner.

図１１は、抵抗を追加した従来の紫外線センサの回路図である。図１１に示す従来の紫外線センサ１０１は、紫外線が当たらないときの抵抗１３１と同程度の抵抗値を有する抵抗１３２を追加し、追加した抵抗１３２を抵抗１３１に対して直列に接続している。端子電極１０６と抵抗１３２の一端１０８との間に３．０Ｖのバイアス電圧を印加し、紫外線センサ１０１に紫外線が当たらない状態で、周辺環境の温度が０℃から８０℃まで変化した場合の端子電極１０５と端子電極１０６との間の電圧の変化を図６のグラフに示す。紫外線が当たらない場合、端子電極１０５と端子電極１０６との間の電圧は約１．５Ｖになる。周辺環境の温度が高くなると、従来の紫外線センサ１０１の抵抗１３１は周辺環境の温度により抵抗値が低下するが、抵抗１３２は外付けの抵抗であるので周辺環境の温度が変化しても抵抗値は変化しない。周辺環境の温度が高くなると端子電極１０５と端子電極１０６との間の電圧は約１．５Ｖよりも低下し、周辺環境の温度が８０℃の時、端子電極１０５と端子電極１０６との間の電圧は約１．１Ｖになる。例えば、周辺環境の温度が０℃の時、波長が３７０ｎｍ、放射強度１ｍＷ／ｃｍ²の紫外線を紫外線センサ１０１に当てると、抵抗１３１の抵抗値が低下し、端子電極１０５と端子電極１０６との間の電圧は約１．０Ｖまで低下するが、該電圧の低下が紫外線を検知したことによるものか、周辺環境の温度が変化したことによるものかを判断することができない。 FIG. 11 is a circuit diagram of a conventional ultraviolet sensor to which a resistor is added. In the conventional ultraviolet sensor 101 shown in FIG. 11, a resistor 132 having a resistance value comparable to that of the resistor 131 when ultraviolet rays do not hit is added, and the added resistor 132 is connected to the resistor 131 in series. A terminal when the bias voltage of 3.0 V is applied between the terminal electrode 106 and one end 108 of the resistor 132 and the temperature of the surrounding environment changes from 0 ° C. to 80 ° C. in a state where the ultraviolet sensor 101 is not exposed to ultraviolet rays. The change in voltage between the electrode 105 and the terminal electrode 106 is shown in the graph of FIG. When ultraviolet rays do not hit, the voltage between the terminal electrode 105 and the terminal electrode 106 is about 1.5V. When the temperature of the surrounding environment increases, the resistance value of the resistor 131 of the conventional ultraviolet sensor 101 decreases depending on the temperature of the surrounding environment. However, since the resistor 132 is an external resistor, the resistance value is maintained even if the temperature of the surrounding environment changes. Does not change. When the temperature of the surrounding environment increases, the voltage between the terminal electrode 105 and the terminal electrode 106 decreases below about 1.5 V. When the temperature of the surrounding environment is 80 ° C., the voltage between the terminal electrode 105 and the terminal electrode 106 is increased. The voltage will be about 1.1V. For example, when the temperature of the surrounding environment is 0 ° C., when ultraviolet light having a wavelength of 370 nm and a radiation intensity of 1 mW / cm ² is applied to the ultraviolet sensor 101, the resistance value of the resistor 131 decreases, and the terminal electrode 105 and the terminal electrode 106 In the meantime, the voltage drops to about 1.0 V, but it cannot be determined whether the voltage drop is due to the detection of ultraviolet rays or the temperature of the surrounding environment has changed.

以上のように、本発明の実施の形態１に係る紫外線センサ１は、基板２内に形成された内部電極７と、基板２の面（第１面）に形成された外部電極３と、内部電極７の一部が外部へ露出した基板２の面（第２面）に形成され、内部電極７と接続された端子電極５と、外部電極３が形成された基板２の面（第１面）及び端子電極５が形成された基板２の面（第２面）と異なる基板２の面（第３面）に形成された端子電極６とを備えているので、外部電極３と端子電極６との間に印加するバイアス電圧を、内部電極７で分圧する回路構成とすることができる。紫外線センサ１は、外部電極３と端子電極６との間に印加するバイアス電圧を、外部電極３と内部電極７との間の電圧、及び内部電極７と端子電極６との間の電圧に分圧することにより、使用される周辺環境の温度による外部電極３と内部電極７との間の抵抗３１の抵抗値の変化と、内部電極７と端子電極６との間の抵抗３２の抵抗値の変化とを相殺するので、酸化物半導体の温度特性に応じて補正した外部電極３と内部電極７との間の電圧値を得ることができる。つまり、紫外線センサ１は、周辺環境の温度に依存することなく、紫外線を検知することができる。また、紫外線センサ１は、ＯＰアンプ等を用いた補正回路が不要なので、製造コストが安くなる。 As described above, the ultraviolet sensor 1 according to Embodiment 1 of the present invention includes the internal electrode 7 formed in the substrate 2, the external electrode 3 formed on the surface (first surface) of the substrate 2, the internal A part of the electrode 7 is formed on the surface (second surface) of the substrate 2 exposed to the outside, the terminal electrode 5 connected to the internal electrode 7 and the surface of the substrate 2 on which the external electrode 3 is formed (first surface) ) And the terminal electrode 6 formed on the surface (third surface) of the substrate 2 different from the surface (second surface) of the substrate 2 on which the terminal electrode 5 is formed, the external electrode 3 and the terminal electrode 6 are provided. A circuit configuration in which the bias voltage applied between the two electrodes is divided by the internal electrode 7 can be employed. The ultraviolet sensor 1 divides a bias voltage applied between the external electrode 3 and the terminal electrode 6 into a voltage between the external electrode 3 and the internal electrode 7 and a voltage between the internal electrode 7 and the terminal electrode 6. The resistance value of the resistor 31 between the external electrode 3 and the internal electrode 7 and the resistance value of the resistor 32 between the internal electrode 7 and the terminal electrode 6 are changed by the temperature of the surrounding environment. Therefore, the voltage value between the external electrode 3 and the internal electrode 7 corrected according to the temperature characteristics of the oxide semiconductor can be obtained. That is, the ultraviolet sensor 1 can detect ultraviolet rays without depending on the temperature of the surrounding environment. Further, since the ultraviolet sensor 1 does not require a correction circuit using an OP amplifier or the like, the manufacturing cost is reduced.

なお、紫外線センサ１は、特に紫外線が当たらないときの抵抗３１と抵抗３２の抵抗値が同じになるように構成する場合に限定されるものではなく、抵抗３１と抵抗３２の抵抗値が異なるように構成しても良い。また、紫外線センサ１は、紫外線を検知するために、外部電極３と内部電極７との間の電圧及び／又は内部電極７と端子電極６との間の電圧を測定する場合に限定されるものではなく、外部電極３と内部電極７との間の電流及び／又は内部電極７と端子電極６との間の電流を測定しても良い。 The ultraviolet sensor 1 is not particularly limited to the case where the resistance values of the resistor 31 and the resistor 32 are the same when the ultraviolet rays are not applied, and the resistance values of the resistor 31 and the resistor 32 are different. You may comprise. The ultraviolet sensor 1 is limited to measuring the voltage between the external electrode 3 and the internal electrode 7 and / or the voltage between the internal electrode 7 and the terminal electrode 6 in order to detect ultraviolet light. Instead, the current between the external electrode 3 and the internal electrode 7 and / or the current between the internal electrode 7 and the terminal electrode 6 may be measured.

さらに、内部電極７と端子電極６との間の抵抗３２は、内部電極７の長さや端子電極６に内部電極を設ける等の設計変更で容易に抵抗値を変更することができる。 Further, the resistance 32 between the internal electrode 7 and the terminal electrode 6 can be easily changed in the design value such as the length of the internal electrode 7 or the provision of the internal electrode on the terminal electrode 6.

（実施の形態２）
図７は、本発明の実施の形態２に係る紫外線センサ１の構成を示す概略図である。図７（ａ）は、本発明の実施の形態２に係る紫外線センサ１の平面図である。図７（ｂ）は、図７（ａ）に示す紫外線センサ１のＢ−Ｂ断面図である。図７（ａ）に示すように、紫外線センサ１は、酸化物半導体で構成された直方体形状の基板２のそれぞれ異なる面に形成された外部電極３、端子電極４、端子電極５、端子電極６を備えている。さらに、紫外線センサ１は、外部電極３と、端子電極５及び端子電極６との間の基板２の面（第１面）に形成された絶縁層８を備えている。また、図７（ｂ）に示すように、紫外線センサ１は、基板２内に、外部電極３と平行に形成された内部電極７を備えている。なお、実施の形態２に係る紫外線センサ１について、図１に示した実施の形態１に係る紫外線センサ１と同じ構成要素については、同じ符号を付して詳細な説明を省略する。 (Embodiment 2)
FIG. 7 is a schematic diagram showing the configuration of the ultraviolet sensor 1 according to Embodiment 2 of the present invention. FIG. 7A is a plan view of the ultraviolet sensor 1 according to Embodiment 2 of the present invention. FIG.7 (b) is BB sectional drawing of the ultraviolet sensor 1 shown to Fig.7 (a). As shown in FIG. 7A, the ultraviolet sensor 1 includes an external electrode 3, a terminal electrode 4, a terminal electrode 5, and a terminal electrode 6 formed on different surfaces of a rectangular parallelepiped substrate 2 made of an oxide semiconductor. It has. Further, the ultraviolet sensor 1 includes an insulating layer 8 formed on the surface (first surface) of the substrate 2 between the external electrode 3 and the terminal electrode 5 and the terminal electrode 6. Further, as shown in FIG. 7B, the ultraviolet sensor 1 includes an internal electrode 7 formed in the substrate 2 in parallel with the external electrode 3. In addition, about the ultraviolet sensor 1 which concerns on Embodiment 2, the same code | symbol is attached | subjected about the same component as the ultraviolet sensor 1 which concerns on Embodiment 1 shown in FIG. 1, and detailed description is abbreviate | omitted.

実施の形態１に係る紫外線センサ１は、図６で示したように、周辺環境の温度が５０℃以上になると、外部電極３と内部電極７との間の電圧が低下する。外部電極３と内部電極７との間の電圧が低下するのは、実施の形態１の図３に示したように外部電極３から端子電極５、及び／又は外部電極３から端子電極６へリーク電流（基板２の表面を流れる電流）が流れているためと考えられる。そこで、本実施の形態２に係る紫外線センサ１では、外部電極３から端子電極５、６へ流れるリーク電流を低減するため、外部電極３と、端子電極５（第１端子電極）及び端子電極６（第２端子電極）との間の基板２の面（第１面）に形成した絶縁層８を備えている。 In the ultraviolet sensor 1 according to the first embodiment, as shown in FIG. 6, when the temperature of the surrounding environment becomes 50 ° C. or higher, the voltage between the external electrode 3 and the internal electrode 7 decreases. The voltage between the external electrode 3 and the internal electrode 7 decreases because of leakage from the external electrode 3 to the terminal electrode 5 and / or from the external electrode 3 to the terminal electrode 6 as shown in FIG. It is considered that current (current flowing through the surface of the substrate 2) flows. Therefore, in the ultraviolet sensor 1 according to the second embodiment, the external electrode 3, the terminal electrode 5 (first terminal electrode), and the terminal electrode 6 are reduced in order to reduce the leakage current flowing from the external electrode 3 to the terminal electrodes 5 and 6. An insulating layer 8 formed on the surface (first surface) of the substrate 2 between the (second terminal electrode) is provided.

絶縁層８を形成する方法は、端子電極４、５、６を形成する前に、すなわち端子電極４、５、６を形成する基板２の異なるそれぞれの面にＡｇペーストを塗布する前に、外部電極３を形成する基板２の面（第１面）にガラスペーストを塗布し、塗布したガラスペーストをＡｇペーストと同時に焼成して絶縁層８を形成する。なお、基板２の面（第１面）の外部電極３を形成する領域にはガラスペーストを塗布しないで、絶縁層８を形成後に、スパッタ法等を用いて外部電極３を形成する。 The method of forming the insulating layer 8 is performed before the terminal electrodes 4, 5, 6 are formed, that is, before the Ag paste is applied to different surfaces of the substrate 2 on which the terminal electrodes 4, 5, 6 are formed. A glass paste is applied to the surface (first surface) of the substrate 2 on which the electrode 3 is to be formed, and the applied glass paste is baked simultaneously with the Ag paste to form the insulating layer 8. It should be noted that the glass paste is not applied to the surface of the substrate 2 (first surface) where the external electrode 3 is to be formed, and the external electrode 3 is formed by sputtering or the like after the insulating layer 8 is formed.

図８は、本発明の実施の形態２に係る紫外線センサ１の周辺環境の温度による外部電極３と内部電極７との間の電圧の変化を示すグラフである。図８は、紫外線センサ１に紫外線が当たらない状態で、周辺環境の温度が０℃から８０℃まで変化した場合の外部電極３と内部電極７との間の電圧の変化を示している。紫外線が当たらない場合、本発明の実施の形態１と同じように、外部電極３と内部電極７との間の電圧は約１．５Ｖになるが、本実施の形態２に係る紫外線センサ１は、外部電極３と、端子電極５及び端子電極６との間の基板２の面（第１面）に絶縁層８を形成して、外部電極３から端子電極５、６へ流れるリーク電流を低減しているので、周辺環境の温度が５０℃以上でも外部電極３と内部電極７との間の電圧は略一定となる。例えば、周辺環境の温度が０℃の時、波長が３７０ｎｍ、放射強度１ｍＷ／ｃｍ²の紫外線を紫外線センサ１に当てると、抵抗３１の抵抗値が低下し、外部電極３と内部電極７との間の電圧は約１．０Ｖまで低下し、紫外線を検知することができる。紫外線が当たったことにより周辺環境の温度が５０℃以上に変化しても、外部電極３と内部電極７との間の電圧は約１．０Ｖのままで略一定となるので、同様に紫外線を検知することができる。 FIG. 8 is a graph showing a change in voltage between the external electrode 3 and the internal electrode 7 due to the temperature of the surrounding environment of the ultraviolet sensor 1 according to Embodiment 2 of the present invention. FIG. 8 shows a change in voltage between the external electrode 3 and the internal electrode 7 when the temperature of the surrounding environment changes from 0 ° C. to 80 ° C. in a state where the ultraviolet sensor 1 is not exposed to ultraviolet rays. When the ultraviolet rays do not hit, the voltage between the external electrode 3 and the internal electrode 7 is about 1.5 V, as in the first embodiment of the present invention, but the ultraviolet sensor 1 according to the second embodiment is The insulating layer 8 is formed on the surface (first surface) of the substrate 2 between the external electrode 3 and the terminal electrode 5 and the terminal electrode 6 to reduce leakage current flowing from the external electrode 3 to the terminal electrodes 5 and 6. Therefore, even when the temperature of the surrounding environment is 50 ° C. or higher, the voltage between the external electrode 3 and the internal electrode 7 becomes substantially constant. For example, when the temperature of the surrounding environment is 0 ° C., when ultraviolet light having a wavelength of 370 nm and a radiation intensity of 1 mW / cm ² is applied to the ultraviolet sensor 1, the resistance value of the resistor 31 decreases, and the external electrode 3 and the internal electrode 7 The voltage between them decreases to about 1.0 V, and ultraviolet rays can be detected. Even if the temperature of the surrounding environment changes to 50 ° C. or more due to the exposure to ultraviolet rays, the voltage between the external electrode 3 and the internal electrode 7 remains substantially constant at about 1.0 V. Can be detected.

以上のように、本発明の実施の形態２に係る紫外線センサ１は、外部電極３と、端子電極５及び端子電極６との間の基板２の面（第１面）に絶縁層８を形成しているので、外部電極３から端子電極５、６へ流れるリーク電流（基板２の表面を流れる電流）を低減することができ、より広い周辺環境の温度範囲で酸化物半導体の温度特性に応じて補正した外部電極３と内部電極７との間の電圧値を得ることができる。つまり、本実施の形態２に係る紫外線センサ１は、より広い温度範囲で周辺環境の温度に依存することなく、紫外線を検知することができる。また、本実施の形態２に係る紫外線センサ１は、ＯＰアンプ等を用いた補正回路が不要なので、製造コストが安くなる。 As described above, in the ultraviolet sensor 1 according to Embodiment 2 of the present invention, the insulating layer 8 is formed on the surface (first surface) of the substrate 2 between the external electrode 3 and the terminal electrode 5 and the terminal electrode 6. As a result, the leakage current flowing from the external electrode 3 to the terminal electrodes 5 and 6 (current flowing on the surface of the substrate 2) can be reduced, and the temperature characteristics of the oxide semiconductor can be adjusted in a wider temperature range of the surrounding environment. Thus, the corrected voltage value between the external electrode 3 and the internal electrode 7 can be obtained. That is, the ultraviolet sensor 1 according to the second embodiment can detect ultraviolet rays without depending on the temperature of the surrounding environment in a wider temperature range. Further, since the ultraviolet sensor 1 according to the second embodiment does not require a correction circuit using an OP amplifier or the like, the manufacturing cost is reduced.

１紫外線センサ
２基板
３外部電極
４、５、６端子電極
７内部電極
８絶縁層
１１電源
２１グリーンシート
３１、３２抵抗 DESCRIPTION OF SYMBOLS 1 Ultraviolet sensor 2 Board | substrate 3 External electrode 4, 5, 6 Terminal electrode 7 Internal electrode 8 Insulating layer 11 Power supply 21 Green sheet 31, 32 Resistance

Claims

A rectangular parallelepiped substrate made of an oxide semiconductor in which ZnO is dissolved in NiO;
An internal electrode formed in the substrate;
An external electrode made of ZnO formed on a part of the first surface of the substrate;
A first terminal electrode formed on the second surface of the substrate that is partially exposed to the outside and connected to the internal electrode;
A second terminal electrode formed on a third surface of the substrate different from the first surface on which the external electrode is formed and the second surface on which the first terminal electrode is formed;
The first terminal electrode and the second terminal electrode are respectively formed on both end faces in the longitudinal direction of the substrate,
One end of the internal electrode is connected to the first terminal electrode, the other end of the internal electrode is not connected to the second terminal electrode,
The external electrode is not connected to the first terminal electrode and the second terminal electrode,
When viewed in plan from the first surface of the substrate, the distance between the other end of the internal electrode and the second terminal electrode is shorter than the distance between the external electrode and the second terminal electrode .
An ultraviolet sensor characterized in that a predetermined voltage applied between the external electrode and the second terminal electrode is divided by the internal electrode.

2. The voltage between the external electrode and the internal electrode and / or the voltage between the internal electrode and the second terminal electrode, which is divided by the internal electrode, is measured. The ultraviolet sensor described.

The ultraviolet sensor according to claim 1, wherein the external electrode is made of a material that transmits ultraviolet light.

4. The semiconductor device according to claim 1, further comprising an insulating layer formed on the first surface of the substrate between the external electrode and the first terminal electrode and the second terminal electrode. 5. The ultraviolet sensor described in 1.