JP2010133773A - Ultraviolet sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect a plurality of ultraviolet rays with different wavelength bands by a single sensor element without upsizing a sensor as a whole. <P>SOLUTION: The ultraviolet sensor 1 includes: a substrate 2; a first sensitive film 3 which is formed on the substrate 2 and changes its resistance value by a first ultraviolet ray having a first wavelength; a second sensitive film 5 which is formed on the substrate 2 and changes its resistance value by a second ultraviolet ray having a second wavelength which is different from the first wavelength; first and second individual electrodes 6, 7 which are formed on the first and second sensitive films 3, 5, respectively; and a common electrode 8 which is formed across the first and second sensitive films 3, 5. A change in the resistance value or the current value between the first and second individual electrodes 6, 7 and the common electrode 8 is detected. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ultraviolet sensor that detects a plurality of ultraviolet rays having different wavelengths.

Conventionally, a first photodiode that detects ultraviolet light having a wavelength λ1, a second photodiode that detects ultraviolet light having a wavelength λ2 that is longer than the wavelength λ1, and a first photodiode based on the detection value of the second photodiode. There is known an ultraviolet sensor provided with a subtractor that subtracts the detected value and outputs a subtracted value (see Patent Document 1). In this ultraviolet sensor, for example, the wavelength λ1 detected by the first photodiode is adjusted to 315 nm, the wavelength λ2 detected by the second photodiode is adjusted to 380 nm, and the wavelength band 380 to 315 nm is determined from the difference between the wavelengths λ2 and λ1. UV-A light is detected.
JP 2004-061417 A

  However, although the conventional ultraviolet sensor can detect a plurality of ultraviolet rays having different wavelengths by adjusting the detection wavelengths λ1 and λ2, sensor elements such as photodiodes are required by the number of detection wavelengths. There is a problem that the whole is enlarged.

  The present invention has been made in view of such points, and an object of the present invention is to provide an ultraviolet sensor capable of detecting a plurality of ultraviolet rays having different wavelengths with a single sensor element without increasing the size of the entire sensor. And

  The ultraviolet sensor according to the present invention is formed on a substrate, a first sensitive film formed on the substrate and having a resistance value changed by a first ultraviolet ray having a first wavelength, and the first sensor. A second sensitive film whose resistance value is changed by a second ultraviolet ray having a second wavelength different from the first wavelength; and first and second individual electrodes respectively formed on the first and second sensitive films; A common electrode formed across the first and second sensitive films, and detects a change in resistance value or current value between the first and second individual electrodes and the common electrode. It is characterized by that.

  According to this configuration, since a change in resistance value or current value between the first and second individual electrodes and the common electrode is detected, the change in the resistance value or current value causes the first ultraviolet ray or the second electrode to change. Ultraviolet rays can be detected. Therefore, it is possible to detect a plurality of ultraviolet rays having different wavelengths with a single sensor element. Further, even when detecting a plurality of ultraviolet rays having different wavelengths, it is not necessary to provide sensor elements as many as the number of detection wavelengths as in the prior art, so that the entire sensor can be reduced in size.

  In the ultraviolet sensor, the first and second sensitive films are laminated on the substrate with an insulating film interposed between the first sensitive film and the second sensitive film, and the common electrode is It is preferable that a part of the lower sensitive film is formed to extend laterally from the end of the upper sensitive film. In this case, for example, the sensitive film on the upper surface can respond to short wavelength ultraviolet rays, and the sensitive film on the substrate side can respond to long wavelength ultraviolet rays.

  According to this configuration, the common electrode is formed by extending a part of the lower sensitive film laminated on the substrate laterally from the end of the upper sensitive film. The sensor element can be downsized and a plurality of ultraviolet rays having different wavelengths can be detected.

  In the ultraviolet sensor, the first and second sensitive films are formed side by side on the same surface of the substrate, and the common electrode is formed at a boundary portion of the first and second sensitive films. Also good.

  In the ultraviolet sensor, a first variable resistor made of the first sensitive film, a first fixed resistor having one end connected to the first individual electrode, and a second made of the second sensitive film. A variable resistor and a second fixed resistor having one end connected to the second individual electrode and the other end connected to the first fixed resistor constitute a bridge circuit to detect a relative change in the resistance value. The structure which performs is considered.

  Further, the ultraviolet sensor can include a detection unit that detects an individual change amount of the resistance value, so that the first ultraviolet ray and the second ultraviolet ray can be individually detected.

  According to the present invention, it is possible to detect a plurality of ultraviolet rays having different wavelengths with a single sensor element without increasing the size of the sensor element.

Hereinafter, an ultraviolet sensor according to an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view schematically showing an ultraviolet sensor according to an embodiment of the present invention. The ultraviolet sensor according to the present embodiment is an ultraviolet sensor that detects two or more ultraviolet rays (for example, UV-A light and UV-B light) having different wavelengths. Here, UV-A (UVA) light refers to light in the wavelength band of the near ultraviolet region, and is light having a wavelength of about 380 to 315 nm. UV-B (UVB) light refers to light in the near-ultraviolet region wavelength band, and is light having a wavelength of about 315 to 280 nm. Hereinafter, a case where UVA light and UVB light are detected will be described as an example.

  As shown in FIG. 1, the ultraviolet sensor 1 is made on a substrate 2 made of silicon, glass, plastic, or the like. A UVA sensitive film (first sensitive film) 3 for detecting UVA light is formed on the substrate 2. The UVA sensitive film 3 is a sensitive film whose resistance value changes when irradiated with UVA light, and is composed of, for example, ZnO or GaN.

  An insulating film 4 is formed on the UVA sensitive film 3, and a UVB sensitive film (second sensitive film) 5 for detecting UVB light is formed through the insulating film 4. The UVB sensitive film 5 is a sensitive film whose resistance value changes when irradiated with UVB light, and is made of, for example, MgZnO or AlGaN. The insulating film 4 is an insulating film capable of transmitting UVA light, and is made of, for example, a silicon oxide film (SiO 2) or aluminum oxide (Al 2 O 3). Both opposite ends of the UVA sensitive film 3 extend outward from the outer edge of the UVB sensitive film 5. In the ultraviolet sensor 1 of the present embodiment, the UVUB sensitive film 5 on the upper surface responds to short wavelength ultraviolet light, and the UVA sensitive film 3 on the substrate 2 side responds to long wavelength ultraviolet light.

  A common electrode 8 formed across the UVA sensitive film 3 and the UVB sensitive film 5 is formed at one end (the right end in FIG. 1) of the extended portion of the UVA sensitive film 3. Specifically, the common electrode 8 is formed by extending a part of the lower (substrate 2 side) UVA sensitive film 3 to the side (outward) from the end of the upper UVB sensitive film 5. Has been. On the other hand, the first individual electrode 6 is pattern-formed at the other end (the left end in FIG. 1) opposite to the end where the common electrode 8 is formed in the extended portion of the UVA sensitive film 3. ing. On the UVB sensitive film 5, the second individual electrode 7 is patterned at the other end (the left end in FIG. 1) opposite to the one end where the common electrode 8 is formed. . The first and second individual electrodes 6 and 7 and the common electrode 8 are made of, for example, gold (Au), platinum (Pt), aluminum (Al), or the like.

  Next, an example of the manufacturing process of the ultraviolet sensor 1 will be described with reference to FIG. FIG. 2 is a cross-sectional view schematically showing an example of the manufacturing process of the ultraviolet sensor 1.

  For example, the UVA sensitive film 3 is formed on the substrate 2 by using a sputtering method or a vapor deposition method (FIG. 2A). Next, an insulating film 4 such as a silicon oxide film is formed on the UVA sensitive film 3, and a UVB sensitive film 5 is formed on the insulating film 4 (FIG. 2B). Next, photolithography is performed through a mask corresponding to the formation region of the UVB sensitive film 5, and the UVB sensitive film 5 and the insulating film 4 other than the formation region of the UVB sensitive film 5 are removed by etching (FIG. 2 ( c)). Next, photolithography is performed through a mask in which regions other than the electrode formation region are patterned, and a metal material such as gold (Au), platinum (Pt), or aluminum (Al) is formed by sputtering. (FIG. 2 (d)). Then, the metal material in the region other than the electrode formation region is removed by lift-off processing, and the first and second individual electrodes 6 and 7 and the common electrode 8 are formed (FIG. 2E).

  In the ultraviolet sensor 1 shown in FIG. 1, the case where the UVA sensitive film 3 and the UVB sensitive film 5 are formed on the same substrate 2 via the insulating film 4 is described as an example. If it is the structure formed so that the sensitive film | membrane 3 and the UVB sensitive film | membrane 5 may be straddled, a structure as shown in FIG. 3 may be sufficient. In the ultraviolet sensor 1a shown in FIG. 3, the UVA-sensitive film 3 is formed on the same substrate 2 on the left side, and the UVB-sensitive film 5 is formed on the right side. First and second individual electrodes 6 and 7 are formed on the outer ends of the upper surfaces of the UVA sensitive film 3 and the UVB sensitive film 5, respectively, and a common electrode is provided so as to cover the boundary portion between the UVA sensitive film 3 and the UVB sensitive film 5 8 is formed.

  Next, an example of a specific ultraviolet detection circuit will be described with reference to FIG. FIG. 4 is a circuit configuration diagram illustrating an example of a detection circuit that detects UVA light and UVB light. As shown in FIG. 4, the detection circuit 10 includes a variable resistor R <b> 1 made of the UVA sensitive film 3, a fixed resistor R <b> 3 having one end connected to the first individual electrode 6, and a variable resistor made of the second sensitive film 5. A bridge circuit is configured by R2 and the fixed resistor R4 having one end connected to the second individual electrode 7 and the other end connected to the fixed resistor R3.

  A connection point P1 between one end of the variable resistor R1 and one end of the variable resistor R2 is configured by the common electrode 8, and a power supply voltage is applied to the connection point P1 and the connection point P2 between the fixed resistor R3 and the fixed resistor R4. ing. A voltage detection unit 11 is connected to a connection point P3 between the other end of the variable resistor R1 configured by the first individual electrode 6 and one end of the fixed resistor R3. A voltage detection unit 11 is connected to a connection point P4 between the other end of the variable resistor R2 configured by the individual electrode 7 and one end of the fixed resistor R4. The voltage detector 11 detects the voltage at the connection points P3 and P4. Here, in the detection circuit 10, when the UVA sensitive film 3 or the UVB sensitive film 5 is not irradiated with ultraviolet rays, the potential between the connection points P1-P3 and between the connection points P1-P4 is fixed to be the same potential. The resistance values of the resistors R3 and R4 are adjusted, and the voltage detected by the voltage detector 11 is configured to be, for example, 0 [V]. That is, the detection circuit 10 is set to a state in which the ratio of the resistance values of the variable resistor R1 and the fixed resistor R3 and the ratio of the resistance values of the variable resistor R2 and the fixed resistor R4 are equal when the ultraviolet rays are not irradiated. It is configured to maintain an equilibrium state.

  The detection circuit 10 configured as described above detects a change in the relative resistance value or current value of the variable resistor R1 made of the UVA sensitive film 3 or the variable resistor R2 made of the UVB sensitive film 5. That is, UVA light or UVB light is detected by reading a relative voltage change between the first and second individual electrodes 6, 7 and the common electrode 8 in accordance with a relative resistance value change. For example, when the UVA light that has passed through the insulating film 4 is irradiated onto the UVA sensitive film 3, the resistance value of the variable resistor R1 decreases, so that a potential difference is generated between the connection point P3 and the connection point P4. Thereby, UVA light can be detected. On the other hand, when the UVB light is irradiated onto the UVB sensitive film 5, the resistance value of the variable resistor R2 decreases, so that a potential difference occurs between the connection point P3 and the connection point P4, and the UVB light can be detected.

  Further, when detecting UVA light or UVB light individually, as shown in FIG. 5, a switch for switching the connection between the connection point (common electrode) P1 and the variable resistor R1 or the variable resistor R2 may be provided. . FIG. 5 is a circuit configuration diagram illustrating an example of a detection circuit that individually detects UVA light and UVB light.

  The detection circuit 20 shown in FIG. 5 is connected to a fixed resistor R5 connected in parallel to the variable resistor R1, a fixed resistor R6 connected in parallel to the variable resistor R2, and a connection point (common electrode) P1. The switches SW1 and SW2 are provided. The switch SW1 switches the connection of the variable resistor R1 or the fixed resistor R5 with the connection point P1, and the switch SW2 switches the connection of the variable resistor R2 or the fixed resistor R6 with the connection point P1. Note that the switches SW1 and SW2 are constituted by diodes, for example. Here, the resistance values of the fixed resistors R5 and R6 are adjusted so that the bridge maintains an equilibrium state when the connections of the variable resistors R1 and R2 are switched by the switches SW1 and SW2. For example, when the switch SW1 is connected to the variable resistor R1 and the switch SW2 is connected to the fixed resistor R6, when the UVA sensitive film 3 is irradiated with UVA light, only the resistance value of the variable resistor R1 changes. A potential difference is generated between the connection point P3 and the connection point P4. That is, the individual change amount of the resistance value of the variable resistor R1 or R2 can be detected by switching the switches SW1 and SW2, and UVA light or UVB light can be detected.

  As described above, according to the present embodiment, the first sensitive film 3 formed on the substrate 2 and having a resistance value changed by the first ultraviolet ray having the first wavelength is formed on the substrate 2. The second sensitive film 5 whose resistance value is changed by a second ultraviolet ray having a second wavelength different from the first wavelength, and the first and second sensitive films 3 and 5 respectively formed on the first and second sensitive films 3 and 5. Individual electrodes 6, 7 and a common electrode 8 formed across the first and second sensitive films 3, 5, and the first and second individual electrodes 6, 7 and the common electrode 8 Changes in resistance value or current value are detected. According to this configuration, since a change in resistance value or current value between the first and second individual electrodes 6 and 7 and the common electrode 8 is detected, the first ultraviolet ray is detected by the change in resistance value or current value. Alternatively, the second ultraviolet ray can be detected. Therefore, it is possible to detect a plurality of ultraviolet rays having different wavelengths with a single sensor element. Further, even when detecting a plurality of ultraviolet rays having different wavelengths, it is not necessary to provide sensor elements as many as the number of detection wavelengths as in the prior art, so that the entire sensor can be reduced in size.

  The present invention is not limited to the above-described embodiment, and can be implemented with various modifications. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited thereto, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  The present invention is applicable to an ultraviolet sensor that detects a plurality of ultraviolet rays having different wavelengths.

It is sectional drawing which showed typically the ultraviolet sensor which concerns on embodiment of this invention. It is sectional drawing which shows typically the manufacturing process of the ultraviolet sensor which concerns on this Embodiment. It is sectional drawing which showed the modification of the ultraviolet sensor typically. It is a circuit block diagram of the detection circuit which concerns on this Embodiment. FIG. 6 is another circuit configuration diagram of the detection circuit according to the present embodiment.

Explanation of symbols

1, 1a UV sensor 2 Substrate 3 UVA sensitive film (first sensitive film)
4 Insulating film 5 UVB sensitive film (second sensitive film)
6 First individual electrode 7 Second individual electrode 8 Common electrode 10, 20 Detection circuit 11 Voltage detection unit R1 Variable resistance (first variable resistance)
R2 variable resistance (second variable resistance)
R3 fixed resistor (first fixed resistor)
R4 fixed resistor (second fixed resistor)
R5, R6 fixed resistance SW1, SW2 switch

Claims (5)

A substrate and a first sensitive film formed on the substrate and having a resistance value changed by a first ultraviolet ray having a first wavelength;
A second sensitive film formed on the substrate and having a resistance value changed by a second ultraviolet ray having a second wavelength different from the first wavelength;
First and second individual electrodes respectively formed on the first and second sensitive films;
A common electrode formed across the first and second sensitive films,
An ultraviolet sensor that detects a change in resistance value or current value between the first and second individual electrodes and the common electrode.   The first and second sensitive films are stacked on the substrate with an insulating film interposed between the first sensitive film and the second sensitive film, and the common electrode is a lower sensitive film. The ultraviolet sensor according to claim 1, wherein a part of the ultraviolet sensor is formed to extend laterally from an end of the upper sensitive film.   The first and second sensitive films are formed side by side on the same surface of the substrate, and the common electrode is formed at a boundary between the first and second sensitive films. The ultraviolet sensor according to claim 1.   A first variable resistor comprising the first sensitive film; a first fixed resistor having one end connected to the first individual electrode; a second variable resistor comprising the second sensitive film; and one end Is connected to the second individual electrode, and a second fixed resistor having the other end connected to the first fixed resistor constitutes a bridge circuit, and detects a relative change in the resistance value. The ultraviolet sensor according to any one of claims 1 to 3.   5. The ultraviolet sensor according to claim 4, further comprising detection means for detecting an individual change amount of the resistance value.

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