JP2015169634A - Optical sensor element, manufacturing method thereof, and illuminance detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical sensor element in which measurement errors due to variation of a driving voltage can be reduced.SOLUTION: A bridge circuit is constituted of first to fourth light detection parts 3 to 6 with first to fourth terminals 21 to 24 therebetween, and each of the first to fourth light detection parts 3 to 6 comprises a photosensitive film 8 formed on a substrate 2 and having photoconductivity and at least a pair of electrodes out of electrodes 9 to 16 being in contact with the photosensitive film 8. A potential difference (output voltage) between the first terminal 21 and the third terminal 23 is measured while a driving voltage is applied between the second terminal 22 and the fourth terminal 24, whereby illuminance of light irradiating an optical sensor element 1 is obtained. The optical sensor element is so designed that a change rate of an output current to the illuminance of irradiating light is different between the first light detection part 3 and the second light detection part 4 and between the third light detection part 5 and the fourth light detection part 6 and an output voltage at illuminance of light for higher detection accuracy is 0 V.

Description

  The present invention relates to an optical sensor element, a method for manufacturing the optical sensor element, and an illuminance detection method performed using the optical sensor element.

As an optical sensor element that is of interest to the present invention, there is, for example, an ultraviolet detection element described in Japanese Patent Application Laid-Open No. 2010-276483 (Patent Document 1). In Patent Document 1, a comb-shaped electrode containing Ti or the like is arranged on a substrate, and an ultraviolet light absorption layer made of Mg _X Zn _1-X O (0 ≦ X ≦ 0.6) so as to cover the comb-shaped electrode. A current output type ultraviolet detection element is described. The principle of light detection of this ultraviolet detection element is that the ultraviolet absorption layer is irradiated with light to generate carriers in the ultraviolet absorption layer, and this carrier is extracted to an external circuit by applying a drive voltage and detected as an output current. It is.

  The technique described in Patent Document 1 aims to reduce variations in electrical characteristics for each optical sensor element, more specifically, variations in output current. Therefore, Patent Document 1 proposes a structure in which the comb-shaped electrode is buried in the ultraviolet light absorption layer.

JP 2010-247683 A

  However, in the technique described in Patent Document 1, no effective measure is taken for fluctuations in output current due to fluctuations in drive voltage. Therefore, as long as the ultraviolet detection element described in Patent Document 1 is used, the measurement error caused by the fluctuation of the drive voltage must be accepted. If measurement errors due to fluctuations in drive voltage cannot be tolerated, a high-precision but expensive power supply must be prepared.

  Accordingly, an object of the present invention is to provide an optical sensor element that can solve the above-described problems and a manufacturing method thereof.

  Another object of the present invention is to provide an illuminance detection method that is advantageously implemented using the above-described optical sensor element.

  An optical sensor element according to the present invention includes a substrate, a photoconductive film having photoconductivity formed on the substrate, and at least one pair of electrodes in contact with the photosensitive film. A light detection unit. In the first to fourth light detection units, the first light detection unit and the second light detection unit are electrically connected via the first connection unit so as to form a bridge circuit by them. The second light detection unit and the third light detection unit are electrically connected via the second connection unit, and the third light detection unit and the fourth light detection unit are connected to the third connection unit. The fourth light detection unit and the first light detection unit are electrically connected via the fourth connection unit. Here, the first connection portion is provided with a first terminal, the second connection portion is provided with a second terminal, the third connection portion is provided with a third terminal, and the fourth connection portion is provided. A fourth terminal is provided at the connection portion.

  And in order to solve the technical problem mentioned above, the change rate (henceforth "current change rate") of the output current with respect to the illumination intensity of the irradiated light is the 1st photon detection part and the 2nd photon detection part. And different between the third light detection unit and the fourth light detection unit.

  Here, as described above, the rate of change in current refers to the rate of change in output current with respect to the illuminance of irradiated light. In other words, the rate of increase in output current accompanying an increase in illuminance. It is.

  For the photoconductive sensor constituting each photodetecting section, when the illuminance of the light irradiated thereon is P and the output current obtained when the light having this illuminance P is irradiated is I, the output with respect to the illuminance P The rate of change of the current I, that is, ΔI / ΔP has a non-zero value.

  The present invention is also directed to an illuminance detection method implemented using the above-described optical sensor element. In the illuminance detection method according to the present invention, by measuring the potential difference (output voltage) between the first and third terminals while applying the drive voltage between the second and fourth terminals, that is, so-called voltage output. It is characterized in that the illuminance of light applied to the optical sensor element is required depending on the method.

  In the case of the voltage output method as described above, the light illuminance at which the output voltage becomes 0 V hardly varies even when the power supply voltage for supplying the drive voltage varies. For example, the illuminance at which the output voltage becomes 0 V can be freely changed by adjusting the overlapping length of the paired electrodes. Therefore, if the output voltage at light illuminance for which detection accuracy is desired is designed to be 0 V, such light illuminance can be measured with high detection accuracy.

  Preferably, the current change rate of the first light detector and the current change rate of the third light detector are substantially equal, and the current change rate of the second light detector and the fourth light detector. Is substantially equivalent to the current change rate. Here, “substantially equivalent” is defined as follows.

When the current change rate of the light detection unit is expressed by ΔI / ΔP as described above, according to this display method,
The current change rate of the first light detection unit is ΔI1 / ΔP1,
The current change rate of the second light detection unit is ΔI2 / ΔP2,
The current change rate of the third light detection unit is ΔI3 / ΔP3, and the current change rate of the fourth light detection unit is ΔI4 / ΔP4.
It is represented by

  As described above, “the current change rate of the first light detection unit and the current change rate of the third light detection unit are substantially equal, and the current change rate of the second light detection unit and the fourth light detection”. "The current change rate of the part is substantially equal" means that the difference between "ΔI1 / ΔP1" and "ΔI3 / ΔP3" and the difference between "ΔI2 / ΔP2" and "ΔI4 / ΔP4" It is 30% or less of ΔI1 / ΔP1-ΔI2 / ΔP2 | and 30% or less of | ΔI3 / ΔP3-ΔI4 / ΔP4 |.

  Preferably, the difference between “ΔI1 / ΔP1” and “ΔI3 / ΔP3” and the difference between “ΔI2 / ΔP2” and “ΔI4 / ΔP4” are 10% or less of | ΔI1 / ΔP1−ΔI2 / ΔP2 | And not more than 10% of | ΔI3 / ΔP3-ΔI4 / ΔP4 |.

  In the present invention, the current change rate as described above is between the first light detection unit and the second light detection unit, and between the third light detection unit and the fourth light detection unit, respectively. In order to realize the difference, in the first preferred embodiment, the interval between the pair of electrodes in the first photodetecting unit is different from the interval between the pair of electrodes in the second photodetecting unit. A configuration is employed in which the distance between the pair of electrodes in the light detection unit is different from the distance between the pair of electrodes in the fourth light detection unit.

  Alternatively, in order to realize the difference in current change rate as described above, in the second preferred embodiment, the material of the light sensitive film in the first light detecting unit and the material of the light sensitive film in the second light detecting unit are Is different, and the material of the light sensitive film in the third light detector is different from the material of the light sensitive film in the fourth light detector.

  Alternatively, in order to realize the difference in current change rate as described above, in the third preferred embodiment, the photosensitive film contains an oxygen element, and in the photosensitive film between the pair of electrodes in the first light detection unit. And the density of oxygen defects in the photosensitive film between the pair of electrodes in the second photodetection unit differ from each other in the photosensitivity film between the pair of electrodes in the third photodetection unit. A configuration is adopted in which the density of oxygen defects is different from the density of oxygen defects in the photosensitive film between the pair of electrodes in the fourth photodetecting section.

  In the third preferred embodiment described above, it is more preferable that at least the electrodes in the first and third light detection units or at least the electrodes in the second and fourth light detection units contain Ti. This is because Ti easily deprives oxygen in the photosensitive film during heat treatment, so that oxygen defects can be efficiently formed in the photosensitive film.

  It should be noted that any one of the first to third preferred embodiments described above may be selectively employed, and two or more embodiments may be employed in combination.

  The present invention is further directed to a method of manufacturing the above-described optical sensor element.

  The method of manufacturing an optical sensor element according to the present invention includes a step of preparing a substrate, a step of forming first to fourth light detection units on the substrate, and a step of forming the light detection unit comprising: Including a step of forming a sensitive film and a step of forming an electrode, and further, after the step of forming the electrode, for adjusting the relationship between the current change rates of the first to fourth photodetecting portions. And a step of heat-treating the light detection unit.

  In relation to the heat treatment step described above, the method for manufacturing an optical sensor element according to the present invention has several embodiments as follows.

  In the first embodiment, the step of forming the electrodes includes a first electrode forming step of forming electrodes for the second and fourth light detection units, and an electrode for the first and third light detection units. A step of heat-treating the photodetecting portion is performed by an electrode formed in the electrode forming step performed first in the first electrode forming step and the second electrode forming step. Including a first heat treatment step for heat-treating a given light detection portion, and a second heat treatment step for heat-treating a light detection portion provided by an electrode formed in an electrode forming step performed later, the first heat treatment step, The heat treatment temperature applied between the first electrode formation step and the second electrode formation step and applied in the first heat treatment step is higher than the heat treatment temperature applied in the second heat treatment step.

  According to the first embodiment described above, the higher heat treatment temperature applied in the first heat treatment step is exerted only on the light detection unit including the electrode formed in the electrode formation step performed earlier. It is. Since the number of oxygen defects formed in the photosensitive film can be changed by changing the heat treatment temperature in this way, the current change rates of the second and fourth photodetecting portions are respectively set to the first and third. It can be made different from the current change rate of the light detection unit.

  In the second embodiment, the step of heat-treating the light detection unit includes a first irradiation step of irradiating the second and fourth light detection units with laser light, and laser light on the first and third light detection units. The intensity of the laser beam irradiated in the first irradiation step is different from the intensity of the laser beam irradiated in the second irradiation step.

  According to the second embodiment described above, in the photosensitive film between the second and fourth light detection units and the first and third light detection units due to the difference in intensity of the irradiated laser light. Since the number of oxygen vacancies formed in the first and second light detection units can be changed, the current change rates of the second and fourth light detection units can be made different from the current change rates of the first and third light detection units, respectively. it can.

  In the third embodiment, the step of forming the electrode is performed for the second and fourth light detection units or the first and third light detection units on the substrate before the step of forming the photosensitive film. Forming an electrode for the first and third photodetecting portions or the second and fourth photodetecting portions on the photosensitive film after the step of forming the electrode and the step of forming the photosensitive film; and , And the step of heat-treating the light detection unit is performed at once on the first to fourth light detection units.

  According to the third embodiment, the electrodes for the second and fourth light detection units or the first and third light detection units are located in the photosensitive film, and the first and third light detection units are provided. Or the electrodes for the second and fourth light detection parts are located on the surface of the photosensitive film. For this reason, there is no photosensitive film between the side surfaces of the electrodes for the light detection part formed after the process of forming the photosensitive film, but the light detection formed before the process of forming the photosensitive film. There is a photosensitive film between each side of the electrode for the part. Therefore, as a result of the heat treatment, more oxygen defects can be generated in the photosensitive film between the side surfaces of the electrode for the photodetecting portion formed before the process of forming the photosensitive film. The current change rate of the fourth light detection unit and the current change rates of the first and third light detection units can be made different.

  In obtaining the illuminance of light using the optical sensor element according to the present invention, a potential difference (output voltage) between the first and third terminals is measured while a drive voltage is applied between the second and fourth terminals. Thus, the illuminance of light applied to the optical sensor element is determined by the voltage output method. In this case, according to the photosensor element of the present invention, the current change rate of the second photodetecting unit is different from the current change rate of the first photodetecting unit, and the current change rate of the fourth photodetecting unit is Since it is different from the current change rate of the third light detection unit, the output voltage can be changed with the change of the light illuminance, and the output voltage 0V can be passed at the predetermined light illuminance. Therefore, if the optical sensor element is designed so that the output voltage at the light illuminance at which detection accuracy is desired to be 0 V, the light illuminance can be measured with high detection accuracy even if the drive voltage varies. Therefore, an expensive power source with high accuracy is not required, and the optical sensor element can be practically used at low cost.

  Further, according to the method for manufacturing an optical sensor element according to the present invention, a desired current change rate can be obtained in the first to fourth optical detection units by heat treatment.

It is a top view which shows the optical sensor element 1 by 1st Embodiment of this invention. It is sectional drawing which follows the line AB of FIG. It is sectional drawing which follows the line CD of FIG. It is a figure which shows the illuminance detection circuit applied in the equivalent circuit of the optical sensor element shown in FIG. 1, and the illuminance detection method implemented using the said optical sensor element. It is a figure for demonstrating the basic principle of the photoconductive type sensor 31 comprised in the photosensor element based on this invention. FIG. 6 is a band diagram of the photosensitive film 32 shown in FIG. 5. It is a top view of the photoconductive type sensor 41a with which the electrode space | interval produced in experiment is 6 micrometers. It is a top view of the photoconductive type sensor 41b with the electrode space | interval produced in experiment of 10 micrometers. It is a figure which shows the IP (output current-light illumination) characteristic of the photoconductive type sensors 41a and 41b shown in FIG. 7 and FIG. 8, respectively. It is a figure which shows the VP (output voltage-light illumination) characteristic of the optical sensor element 1 produced in experiment. For a photoconductive sensor having a structure as shown in FIG. 7 having an electrode interval of 10 μm and an electrode overlap length of 930 μm, which was produced as a comparative example in the experiment, IP (output current−light illuminance) when the power supply voltage was varied ) Is a diagram showing characteristics. It is a figure which shows the VP (output voltage-light illumination intensity) characteristic at the time of changing a power supply voltage about the optical sensor element 1 produced in experiment. It is sectional drawing corresponding to FIG. 2 which shows the optical sensor element 1a by 2nd Embodiment of this invention. It is sectional drawing which shows the optical sensor element 1b by 3rd Embodiment of this invention, and has shown the cross section which passes along a 1st photon detection part, and the cross section which passes along a 2nd photon detection part. It is sectional drawing for demonstrating the modification about the manufacturing method of an optical sensor element. It is sectional drawing for demonstrating the other modification about the manufacturing method of an optical sensor element.

  With reference to FIG. 1 thru | or FIG. 3, the optical sensor element 1 by 1st Embodiment of this invention is demonstrated. In FIG. 1, elements included in the optical sensor element 1 are illustrated in a state where the elements existing inside that are not visible in appearance are also seen through.

  The optical sensor element 1 is on the substrate 2 so as to cover the substrate 2, the first to fourth light detection units 3 to 6 configured on the substrate 2, and the first to fourth light detection units 3 to 6. And a protective film 7 formed thereon.

  The substrate 2 is made of glass, for example. When the optical sensor element 1 detects light through the substrate 2, a transparent glass substrate is used as the substrate 2. In the case of detecting light from the protective film side 7, the substrate 2 may not be transparent.

  The photodetecting units 3 to 6 are configured by a photosensitive film 8 having photoconductivity formed on the substrate 2 and electrodes 9 to 16 in contact with the photosensitive film 8. More specifically, the first light detection unit 3 includes a photosensitive film 8 and a pair of electrodes 9 and 10. The second light detection unit 4 includes a light sensitive film 8 and a pair of electrodes 11 and 12. The third light detection unit 5 includes a photosensitive film 8 and a pair of electrodes 13 and 14. The fourth light detection unit 6 includes a photosensitive film 8 and a pair of electrodes 15 and 16.

  In this embodiment, the electrodes 9 to 16 are formed on the substrate 2 and covered with the photosensitive film 8.

  The electrodes 9 and 10 in the first light detection unit 3 described above have a comb shape having a plurality of electrode fingers inserted between each other. Comb-shaped electrodes 9 and 10 are formed by adding the overlapping lengths of adjacent electrode fingers among a plurality of electrode fingers 9 and 10 as compared to, for example, electrodes 11 and 12 in second light detection unit 4. The overlapping length of the electrodes can be made longer. The electrodes 13 and 14 in the third photodetecting unit 5 have a similar comb shape.

The photosensitive film 8 may be made of any material as long as it absorbs predetermined light and forms electrons and holes. As the material of the photosensitive film 8, ZnO, In ₂ O ₃ , SnO ₂ or the like having a band gap of about 3.2 eV is used when detecting ultraviolet rays. The material of the photosensitive film 8 is amorphous Si having a band gap of about 1.7 eV when detecting visible light. Among the materials described above, oxides such as ZnO, In ₂ O ₃ , and SnO ₂ have oxygen defects as defects that recombine carriers. Note that since amorphous Si is not an oxide, it has structural defects, not oxygen defects, as defects for recombining carriers.

  The material for the electrodes 9 to 16 may be any material as long as it conducts electricity, but is preferably a material that can obtain ohmic contact with the photosensitive film 8. Further, it is desirable that the material has good adhesion to the photosensitive film 8. For example, Ti or Pt can satisfy these requirements. Further, all of the electrodes 9 to 16 are made of a common material, or, for example, the electrodes 9, 10, 13 and 14 for the first and third photodetecting units 3 and 5, the second and The materials may be different between the electrodes 11, 12, 15 and 16 for the fourth light detection units 4 and 6.

As a material for the protective film 7, SiO ₂ , Al ₂ O ₃ , SiN, and the like are preferable from the viewpoint of moisture resistance, and a resin is preferable from the viewpoint of reducing external force. The protective film 7 may have a laminated structure of resin / SiO ₂ or the like. When light is detected through the protective film 7, it is desirable that the material of the protective film 7 has a light absorption coefficient as small as possible in the light wavelength region to be detected.

  The first to fourth light detection units 3 to 6 described above are electrically connected to form a bridge circuit as shown in FIG. More specifically, the first light detection unit 3 and the second light detection unit 4 are electrically connected via the first connection unit 17. The second light detection unit 4 and the third light detection unit 5 are electrically connected via the second connection unit 18. The third light detection unit 5 and the fourth light detection unit 6 are electrically connected via a third connection unit 19. The fourth light detection unit 6 and the first light detection unit 3 are electrically connected via the fourth connection unit 20. In FIG. 1, portions corresponding to these connection portions 17 to 20 are indicated by reference numerals “17” to “20”, respectively.

  In the first to fourth connection portions 17 to 20 described above, first to fourth terminals 21 to 24 are provided, respectively. In this embodiment, as can be seen from FIG. 3, the terminals 21 to 24 are provided by parts of the connection portions 17 to 20 exposed by removing specific portions of the photosensitive film 8 and the protective film 7. It is. However, a conductive material such as solder is introduced into the removed portion so as to be electrically connected to each part of the connection portions 17 to 20, and the connection portions 17 to 20 into which the conductive material is introduced are connected to the terminals 21. It is good also as ~ 24.

  In the optical sensor element 1, as can be seen from FIG. 1, a plurality of electrode fingers provided in the comb electrodes 9 and 10 for the first light detection unit 3 and a comb electrode for the third light detection unit 5. A plurality of electrode fingers included in 13 and 14 are arranged in the same direction, and a second space is provided between the region where the electrodes 9 and 10 are located and the region where the electrodes 13 and 14 are located. Electrodes 11 and 12 for the light detector 4 and electrodes 15 and 16 for the fourth light detector 6 are arranged. Such an arrangement is advantageous in reducing the size of the optical sensor element 1 because the area necessary for arranging the electrodes 9 to 16 is reduced.

  In such an optical sensor element 1, when ΔI / ΔP (rate of change of output current with respect to illuminance) is abbreviated as current change rate, the current change rate of the second light detection unit 4 is equal to that of the first light detection unit 3. It is different from the current change rate, and the current change rate of the fourth light detection unit 6 is different from the current change rate of the third light detection unit 5. The current change rate is an increase rate of the output current as the illuminance increases. The fact that the current change rates are different from each other will be described in more detail by taking the first light detection unit 3 and the second light detection unit 4 as an example.

When the illuminance is 1 mW / cm ² , it is assumed that the output current is 10 ⁻⁶ A in the first light detection unit 3 and the output current is 10 ⁻⁶ A in the second light detection unit 4. Next, when the illuminance is ² mW / cm ² , the output current of the first light detection unit 3 is 2 × 10 ⁻⁶ A, for example, twice, but the output current of the second light detection unit 4 is 2 × 10 ⁻⁶ A. For example, suppose that 5 × 10 ⁻⁶ A is obtained. In such a situation, the change rate of the output current with respect to the illuminance of the irradiated light, that is, the current change rate is different between the first light detection unit 3 and the second light detection unit 4. Become. In the above example, if the illuminance is ² mW / cm ² , the output current of the first light detection unit 3 is doubled to 2 × 10 ⁻⁶ A, and the output current of the second light detection unit 4 is also doubled. Is 2 × 10 ⁻⁶ A, which is twice the same, the current change rates are twice the same, and the current change rates are not different from each other.

  In this embodiment, in order to obtain the difference in current change rate as described above, the pair of the second light detection unit 4 is compared with the distance between the pair of electrodes 9 and 10 in the first light detection unit 3. The distance between the electrodes 11 and 12 of the fourth light detector 6 is narrowed, and the pair of electrodes 15 and 4 in the fourth light detector 6 and the distance between the pair of electrodes 13 and 14 in the third light detector 5 and The interval between 16 is narrowed. Here, the “interval” corresponds to the distance between the opposing surfaces of a pair of electrodes.

  This will be described below with an experimental example. In addition, the absolute value of output current becomes large, so that the space | interval between electrodes is narrow.

  In the optical sensor element 1, each of the light detection units 3 to 6 constitutes a photoconductive sensor 31 whose basic principle will be described below with reference to FIGS. 5 and 6.

  As shown in FIG. 5, the photoconductive sensor 31 includes a light sensitive film 32 and a pair of electrodes 33 and 34 in contact with the light sensitive film 32. When the light sensitive film 32 is irradiated with light 35, carriers (electrons 36 and holes 37) as shown in FIGS. 5 and 6 are generated. Carriers 36 and 37 move due to diffusion caused by an electric field or carrier concentration distribution generated between electrodes 33 and 34, and reach the electrode 33 or 34 without being recombined, and are output to the outside as current. As the illuminance of the light 35 increases, the generated carriers 36 and 37 increase, and the output current also increases. At a constant illuminance, the output current decreases as the recombination amount in the photosensitive film 32 increases.

  The present inventor conducted the following experiment.

[Experimental Example 1]
FIGS. 7 and 8 are plan views showing photoconductive sensors 41a and 41b, respectively, prepared as samples in this experiment. In the photoconductive sensors 41a and 41b, the ultraviolet detection ZnO sensitive film 42 was used as the light sensitive film. On the ZnO sensitive film 42, in the photoconductive sensor 41a shown in FIG. 7, a pair of comb electrodes 43a and 44a having an electrode interval of 6 μm and an electrode overlap length of 3540 μm were formed. On the ZnO sensitive film 42, in the photoconductive sensor 41b shown in FIG. 8, a pair of comb electrodes 43b and 44b having an electrode interval of 10 μm and an electrode overlap length of 3540 μm were formed. Here, the electrode overlap length is the sum of the lengths of the electrode fingers provided in the adjacent comb electrodes 43a and the opposing portions of the electrode fingers provided in the comb electrodes 44a.

  In these photoconductive sensors 41a and 41b, the ammeter is changed between the electrodes 43a and 44a and between the electrodes 43b and 44b while changing the light illuminance while applying a fixed voltage of 3 V from the fixed voltage source 45, respectively. The output current was measured at 46. The resulting IP (output current-light illuminance) characteristics are shown in FIG.

  In FIG. 9, the characteristic of the photoconductive sensor 41a is indicated by “electrode interval 6 μm”, and the characteristic of the photoconductive sensor 41b is indicated by “electrode interval 10 μm”. FIG. 9 shows that the photoconductive sensor 41a having the “electrode interval of 6 μm” is larger than the photoconductive sensor 41b having the “electrode interval of 10 μm” when comparing the output current [A] at the same light illuminance. The difference is over one digit.

  In FIG. 9, it seems that there is not much difference in inclination between “electrode spacing 6 μm” and “electrode spacing 10 μm”, but the vertical axis in FIG. 9 indicates that the output current is displayed on a logarithmic scale. Considering the above, it can be seen that the current change rate (ΔI / ΔP) is different between the photoconductive sensor 41a having the “electrode interval of 6 μm” and the photoconductive sensor 41b having the “electrode interval of 10 μm”.

  As described above, this is because the second photodetection in the photosensor element 1 shown in FIGS. 1 to 3 is larger than the distance between the pair of electrodes 9 and 10 in the first photodetection unit 3. The distance between the pair of electrodes 11 and 12 in the section 4 is narrowed, and 1 in the fourth light detection section 6 is smaller than the distance between the pair of electrodes 13 and 14 in the third light detection section 5. By reducing the distance between the pair of electrodes 15 and 16, the current change rate of the second light detection unit 4 is different from the current change rate of the first light detection unit 3, and the fourth light detection unit This confirms that the current change rate of 6 is different from the current change rate of the third light detection unit 5.

  In this optical sensor element 1, the current change rate of the first light detection unit 3 and the current change rate of the third light detection unit 5 are substantially equal, and the current change rate of the second light detection unit 4. And the current change rate of the fourth light detection unit 6 are substantially equal. That is, the distance between the pair of electrodes 9 and 10 in the first light detection unit 3 and the distance between the pair of electrodes 13 and 14 in the third light detection unit 5 are substantially equal. The distance between the pair of electrodes 11 and 12 in the second light detection unit 4 is substantially the same as the distance between the pair of electrodes 15 and 16 in the fourth light detection unit 6.

  In order to obtain the illuminance of the light applied to the photosensor element 1, a fixed voltage is applied so that a drive voltage is applied between the second and fourth terminals 22 and 24 as shown in FIG. While connecting the source 25, the potential difference between the first and third terminals 21 and 23 is measured by a voltmeter 26. This is an illuminance detection method using a voltage output method. Although not shown in the illuminance detection circuit shown in FIG. 4, a noise removal circuit, an amplification circuit, or the like may be added as necessary. On the other hand, the method using the ammeter 46 shown in FIG. 7 or FIG. 8 is an illuminance detection method using a current output method.

  Next, in order to confirm that the measurement by the voltage output method is superior to the measurement by the current output method, the following experiment was performed.

[Experiment 2]
The optical sensor element 1 described with reference to FIGS. 1 to 3 was produced as follows.

An electrode lift-off pattern was formed on the glass substrate 2 having a thickness of 0.35 mm with a photoresist. Next, after forming a Ti film to be the electrodes 9 to 16 having a thickness of 50 nm by electron beam evaporation, electrodes 9 to 16 were formed by performing lift-off in an organic solvent. Next, using a high frequency magnetron sputtering method, a ZnO thin film as a photosensitive film 7 was formed with a thickness of 140 nm, and subsequently, a SiO ₂ thin film as a protective film 7 was formed with a thickness of 300 nm.

Next, an annealing process is performed at 290 ° C. for 2 hours as a heat treatment, and then an etching pattern is formed with a photoresist, and a protective film 7 made of a SiO ₂ thin film covering portions to be terminals 21 to 24 is formed. A part and a part of the photosensitive film 8 made of a ZnO thin film were removed by etching.

  Thus, the optical sensor element 1 used as a sample was produced. In this photosensor element 1, the electrodes 9 and 10 in the first photodetecting unit 3 and the electrodes 13 and 14 in the third photodetecting unit 5 have an electrode interval of 10 μm, an electrode overlap length of 930 μm, The electrodes 11 and 12 in the photodetecting section 4 and the electrodes 15 and 16 in the fourth photodetecting section 6 have an electrode interval of 6 μm and an electrode overlap length of 20 μm.

Next, with respect to the optical sensor element 1 as the sample, a light illuminance detection experiment was performed using an illuminance detection circuit as shown in FIG. Here, while applying a drive voltage of 3 V from the fixed voltage source 25 between the second and fourth terminals 22 and 24 shown in FIG. 4, ultraviolet (UV) light having an illuminance of 1 to 10 mW / cm ² is applied at 1 mW / cm ^2. Irradiation was performed from the glass substrate 2 side in increments of cm ² , and the output voltage between the first and third terminals 21 and 23 was measured by the voltmeter 26 at each illuminance. The result is shown in FIG. As can be seen from FIG. 10, the light illuminance can be detected from the value of the output voltage.

In this experimental example, the optical sensor element 1 is designed so as to be able to accurately detect the near UV illuminance 5 mW / cm ^2, the output voltage when the UV intensity becomes 5 mW / cm ² was set to 0V.

Next, the detection accuracy in the vicinity of 5 mW / cm ^{2 of} UV illuminance when the power supply voltage fluctuates by ± 10% was compared between the voltage output method and the current output method. The optical sensor element 1 described above was used as an element for obtaining the detection accuracy of the voltage output method. On the other hand, as an element for obtaining the detection accuracy of the current output method, the photoconductive sensor 41a or 41b having the structure as shown in FIG. 7 or FIG. 8 is used, the electrode interval is 10 μm, and the electrode overlap length is 930 μm. .

In the current output method,
(1) When the UV illuminance is 4 mW / cm ² , the output current is 3.71E-8A, but when the power supply voltage fluctuates ± 10%, the output current of 3.71E-8A is Detected in the range of 4.4 mW / cm ² ,
(2) When the UV illuminance is 5 mW / cm ² , the output current is 4.85E-8A, but when the power supply voltage fluctuates ± 10%, the output current of 4.85E-8A is Detected in the range of 5.4 mW / cm ² ,
(3) When the UV illuminance is 6 mW / cm ² , the output current is 6.18E-8A, but when the power supply voltage fluctuates ± 10%, the output current of 6.18E-8A is It was detected in the range of 6.5 mW / cm ² .

  FIG. 11 is a graph showing the IP (output current-light illuminance) characteristics of the current output type element when the power supply voltage fluctuates by ± 10%.

On the other hand, in the voltage output method,
(1) When the UV illuminance is 4 mW / cm ² , the output voltage is 0.12 V, but when the power supply voltage fluctuates ± 10%, the output voltage of 0.12 V is the UV illuminance of 3.9 to 4.1 mW / detected in the range of cm ² ,
(2) When the UV illuminance is 5 mW / cm ² , the output voltage becomes 0 V, but even when the power supply voltage fluctuates ± 10%, the output voltage of 0 V is detected with the UV illuminance of 5 mW / cm ² ,
(3) When the UV illuminance is 6 mW / cm ² , the output voltage is −0.12 V. However, when the power supply voltage fluctuates ± 10%, the output voltage of −0.12 V is the UV illuminance 5.9 to 6 Detected in the range of ² mW / cm ² .

  FIG. 12 is a graph showing the VP (output voltage-light illuminance) characteristics of the voltage output type element when the power supply voltage fluctuates by ± 10%.

As can be seen from a comparison between FIG. 11 and FIG. 12, the voltage output method is more effective than the current output method even when the power supply voltage fluctuates in the above-described range of UV illuminance of 4 to 6 mW / cm ^2. Will also improve the detection accuracy. In the voltage output method, high detection accuracy can be obtained for the following reason.

  In the optical sensor element 1 according to the present invention, the current change rate of the second light detection unit 4 is different from the current change rate of the first light detection unit 3, and the current change rate of the fourth light detection unit 6 is the same. Since the current change rate of the third light detection unit 5 is different, the potential at the first terminal 21 between the first light detection unit 3 and the second light detection unit 4 increases as the light illuminance increases. The difference between the potential at the third terminal 23 between the third light detection unit 5 and the fourth light detection unit 6 can be close to 0 V at a predetermined light illuminance. As apparent from FIG. 12, when the output voltage is around 0V, the error in the output voltage is small even if the drive voltage fluctuates. Therefore, if the output voltage at light illuminance for which detection accuracy is desired to be improved is designed to be 0 V, measurement errors due to fluctuations in drive voltage can be suppressed.

In the experimental example described above, since the optical sensor element 1 is adapted to accurately detect the near UV illuminance 5 mW / cm ^2, the output voltage when the UV intensity becomes 5 mW / cm ² was set to 0V . Thus, the UV illuminance at which the output voltage is 0 V does not vary even when the power supply voltage varies. The UV illuminance at which the output voltage becomes 0 V can be freely designed by changing the overlapping length of the electrodes 9 to 16 in each of the light detection units 3 to 6. Therefore, it is possible to design the output voltage of UV illuminance for which detection accuracy is desired to be 0V.

  In general, in the manufacturing process of the optical sensor element, heat treatment is performed in an appropriate process after the formation of the photosensitive film. The “annealing treatment at 290 ° C. for 2 hours” in Experimental Example 2 described above corresponds to this heat treatment. The heat treatment increases oxygen defects in the vicinity of the electrode in the photosensitive film, and thus works to increase the absolute value of the output current of the light detection unit. During this heat treatment, it has been found that if an electrode is already formed and this electrode contains Ti, the electrode can more easily take oxygen in the photosensitive film and oxygen defects can be formed more efficiently. Therefore, as will be described in detail in the embodiments to be described later, the heat treatment can also contribute to the current change rate adjustment of the light detection unit.

  As described above, when the electrode contains Ti, the electrode is more likely to deprive the photosensitive film of oxygen, so that oxygen defects can be formed more efficiently in the photosensitive film, resulting in a current change rate. Can be changed. From this, the electrode containing Ti is employed in the first and third light detection units 3 and 5, or is employed in the second and fourth light detection units 4 and 6. It is enough. In the other light detection part, the electrode which does not contain Ti, for example, contains Pt may be employ | adopted.

  In the case of the photosensor element 1 described with reference to FIGS. 1 to 3, basically, the first and third photodetecting units 3 and 5 and the second and Although the difference in current change rate between the four light detection units 4 and 6 is generated, the current change rate adjustment by heat treatment may be performed in addition to this.

  Next, an optical sensor element 13a according to a second embodiment of the present invention will be described with reference to FIG. FIG. 13 is a cross-sectional view corresponding to FIG. In FIG. 13, elements corresponding to the elements shown in FIG. 2 are denoted by the same reference numerals, and redundant description is omitted.

  In the optical sensor element 1 shown in FIG. 2 described above, the electrodes 9 to 16 are formed on the substrate 2 so as to be embedded in the photosensitive film 8, but in the optical sensor element 1a shown in FIG. ˜16 are formed on the photosensitive film 8. Such a difference has the meaning described below. In FIG. 13, only the electrodes 9, 10, 13, and 14 among the electrodes 9 to 16 are illustrated, but the electrodes 11, 12, 15, and 16 are similarly formed on the photosensitive film 8.

  In the optical sensor element 1a shown in FIG. 13, the photosensitive film 8 is not present between the side surfaces of the electrodes 9-16. Therefore, in the optical sensor element 1a, current flows through the photosensitive film 8 only along the lower surfaces of the electrodes 9-16. On the other hand, in the optical sensor element 1 shown in FIG. 2, current flows through the photosensitive film 8 between the surfaces including the upper surfaces and the side surfaces of the electrodes 9 to 16. Thus, the optical sensor element 1 shown in FIG. 2 and the optical sensor element 1a shown in FIG. 13 differ in the volume of the portion where the current flows in the photosensitive film 8 sandwiched between the electrodes.

  As described above, as a result of the heat treatment, oxygen defects are generated in the vicinity of the electrodes 9 to 16 in the photosensitive film 8. In this case, the number of defects in the portion in contact with the electrodes 9 to 16 is not so different between the photosensor element 1 shown in FIG. 2 and the photosensor element 1a shown in FIG. However, as described above, since the volume of the portion where the current flows in the photosensitive film 8 sandwiched between the electrodes is different, the number of oxygen defects per unit volume between the electrodes, that is, the defect density, is shown in FIG. The optical sensor element 1 shown has a higher defect density than the optical sensor element 1a shown in FIG. As a result, the current change rate can be made different between the optical sensor element 1 shown in FIG. 2 and the optical sensor element 1a shown in FIG.

  In consideration of the above differences, the characteristics of the optical sensor element can be controlled by selecting which structure of the optical sensor element 1 shown in FIG. 2 and the optical sensor element 1a shown in FIG.

  With respect to the optical sensor elements 1 and 1a according to the first and second embodiments described above, since the electrode forming process and the heat treatment process are each completed once in manufacturing them, the manufacturing process is not complicated. In addition, the manufacturing cost can be kept relatively low.

  An optical sensor element 1b according to a third embodiment of the present invention will be described with reference to FIG. In FIG. 14, the left half shows a cross section passing through the first light detection unit 3, and the right half shows a cross section passing through the second light detection unit 4. In FIG. 14, elements corresponding to the elements shown in FIG. 1 or FIG.

  In the optical sensor element 1b shown in FIG. 14, the electrodes 9 and 10 in the first light detection unit 3 are formed on the photosensitive film 7, and the electrodes 11 and 12 in the second light detection unit 4 are formed on the substrate 2. It is formed so as to be buried in the photosensitive film 8 above. Although not shown, the electrodes 13 and 14 in the third light detection unit 5 are also formed on the photosensitive film 7 as in the case of the electrodes 9 and 10 in the first light detection unit 3, and the fourth light detection is performed. Similarly to the electrodes 11 and 12 in the second light detection unit 4, the electrodes 15 and 16 in the unit 6 are also formed so as to be embedded in the photosensitive film 8 on the substrate 2.

  In the optical sensor element 1b shown in FIG. 14, the electrodes 9 and 10 and the electrodes 11 and 12 are not located on the same plane, and the electrodes 13 and 14 and the electrodes 15 and 16 are located on the same plane. Although not shown, the electrical connection between the first to fourth light detection units 3 to 6 is, for example, a conductor penetrating the photosensitive film 8 in the thickness direction or the outer periphery of the photosensitive film 8. This is achieved through a conductor that extends to

  In the manufacturing process for obtaining the optical sensor element 1b shown in FIG. 14, heat treatment is usually performed as described above. For example, when heat treatment is performed in a state where the photosensitive film 8 and the electrodes 9 to 16 are formed, oxygen defects are brought about in the vicinity of the electrodes 9 to 16 in the photosensitive film 8.

  As described above, the electrodes 9 and 10 for the first light detection unit 3 are formed on the light sensitive film 8, while the electrodes 11 and 12 for the second light detection unit 4 are formed of the light sensitive film 8. The volume of the portion of the photosensitive film 8 sandwiched between the former electrodes 9 and 10 through which the current flows is equal to the photosensitive film sandwiched between the latter electrodes 11 and 12. 8 is smaller than the volume of the portion through which the current flows.

  Therefore, when viewed in terms of the number of oxygen defects per unit volume between the electrodes, that is, the defect density, the second light detection unit 4 has a higher defect density than the first light detection unit 3. As a result, the current change rate can be made different between the second light detection unit 4 and the first light detection unit 3.

  In addition, the above-described heat treatment may sometimes cause a change in material inside the photosensitive film 8. That is, the photosensitive film 8 is in contact with the substrate 2, but in the vicinity of the substrate 2 in the photosensitive film 8, the photosensitive film 8 is easily affected by the substrate 2 at the time of film formation. May not be easily affected by the substrate 2. Therefore, the vicinity of the substrate 2 in the photosensitive film 8 where the electrodes 11, 12, 15 and 16 for the second and fourth light detection units 4 and 6 are located, and the first and third light detection units In the portion of the photosensitive film 8 away from the substrate 2 where the electrodes 9, 10, 13 and 14 for 3 and 5 are located, the material of the photosensitive film 8 may be different. In some cases, the current change rates of the second and fourth light detection units 4 and 6 may be different from the current change rates of the first and third light detection units 3 and 5.

  Next, with reference to FIG. 15, the modification about the manufacturing method of an optical sensor element is demonstrated. In FIG. 15, in order to describe the manufacturing method, the photosensor element 1 a shown in FIG. 13, that is, the one in which the electrodes 9 to 16 are formed on the photosensitive film 8 is taken up. The manufacturing method shown in FIG. 15 is characterized in that the heat treatment performed in the manufacturing process for obtaining the optical sensor element 1a is in two stages.

  First, as shown in FIG. 15 (1), the photosensitive film 8 is formed on the substrate 2, and then the electrodes 11 and 12 for the second light detection unit 4 are formed on the photosensitive film 8. A first electrode forming step is performed. Although not shown, electrodes 15 and 16 for the fourth light detection unit 6 are also formed at the same time. At this stage, the first heat treatment step, that is, the first heat treatment step is performed at a relatively high temperature.

  Next, as shown in FIG. 15 (2), a second electrode forming step for forming electrodes 9 and 10 for the first light detection unit 3 on the photosensitive film 8 is performed. Although not shown, electrodes 13 and 14 for the third photodetecting unit 5 are also formed at the same time. At this stage, the second heat treatment step, that is, the second heat treatment step is performed at a temperature lower than that of the first heat treatment step.

  If the two-stage heat treatment as described above is employed, the first and second light detection units 4 and 6 that have undergone the first heat treatment at a higher temperature are not subjected to the first heat treatment. Compared with the third light detection units 3 and 5, the oxygen defect density can be made higher, and therefore the current change rate can be made different.

  Next, with reference to FIG. 16, another modified example of the method for manufacturing the optical sensor element will be described. In FIG. 16, as in the case of FIG. 15, the optical sensor element 1a shown in FIG. 13, that is, the one in which the electrodes 9 to 16 are formed on the photosensitive film 8 is taken up to describe the manufacturing method. Yes. The manufacturing method shown in FIG. 16 also employs a two-stage heat treatment, which is characterized by the laser light irradiation.

  First, as shown in FIG. 16 (1), a photosensitive film 8 is formed on the substrate 2, and then electrodes for the first and second light detection units 3 and 4 are formed on the photosensitive film 8. 9-12 are formed. Although not shown, electrodes 13 to 16 for the third and fourth light detection units 5 and 6 are also formed at the same time.

  Next, as shown in FIG. 16 (2), a first irradiation step of locally irradiating the second light detection unit 4 with the laser light 49 is performed. The laser light 49 has a relatively large laser intensity, and therefore the second light detection unit 4 is heat-treated at a relatively high temperature. Although not shown, similarly, the first irradiation step of locally irradiating the fourth light detection unit 6 with the laser beam 49 having a relatively large laser intensity is performed.

  Next, as shown in FIG. 16 (3), a second irradiation step of irradiating the first light detection unit 3 with the laser beam 50 is performed. The laser beam 50 has a relatively small laser intensity, and therefore the first light detection unit 3 is heat-treated at a relatively low temperature. Although not shown, similarly, the second irradiation step of irradiating the third light detection unit 5 with the laser beam 50 having a relatively small laser intensity is performed.

  As a result of the irradiation with the laser beams 49 and 50 as described above, the second and fourth light detectors 4 and 6 that have received the irradiation with the laser beam 49 with the higher laser intensity irradiate with the laser beam with the lower laser intensity. Compared with the first and third photodetecting units 3 and 5 that receive only the oxygen defect density, the oxygen defect density can be made higher, and therefore the current change rate can be made different from each other.

  The first irradiation process described above may be performed after the second irradiation process, or the first irradiation process and the second irradiation process may be performed simultaneously. Further, the laser beam 49 irradiated in the first irradiation step must be locally irradiated to the second and fourth light detection units 4 and 6, but the laser beam irradiated in the second irradiation step. Since 50 is of a lower laser intensity, in addition to the first and third light detection units 3 and 5, for example, the second and fourth light detection units 4 and 6 may be irradiated. .

  Also in the manufacturing process for obtaining the photosensor element 1b shown in FIG. 14, the current change rate between the first photodetection unit 3 and the second photodetection unit 4 and the third photodetection unit. In order to make the current change rates different between 5 and the fourth light detection unit 6, it is possible to employ a two-stage heat treatment. More specifically, in the state where the electrodes 11, 12, 15 and 16 and the photosensitive film 8 for the second and fourth light detection units 4 and 6 and the photosensitive film 8 are formed on the substrate 2, as the first heat treatment step, The first heat treatment is performed at a relatively high temperature, and then the electrodes 9, 10, 13 and 14 for the first and third light detection units 3 and 5 are formed on the photosensitive film 8, and then the first As the second heat treatment step, the second heat treatment is performed at a relatively low temperature.

  If the two-stage heat treatment as described above is employed, the first and second light detection units 4 and 6 that have undergone the first heat treatment at a higher temperature are not subjected to the first heat treatment. Compared with the third light detection units 3 and 5, the oxygen defect density can be made higher, and therefore the current change rate can be made different from each other.

  14 to 16, the distance between the pair of electrodes 9 and 10 in the first light detection unit 3 is equal to the distance between the pair of electrodes 11 and 12 in the second light detection unit 4. Although illustrated, also in these embodiments, the distance between the pair of electrodes 11 and 12 in the second light detection unit 4 is larger than the distance between the pair of electrodes 9 and 10 in the first light detection unit 3. The interval is narrowed, and the interval between the pair of electrodes 15 and 16 in the fourth photodetecting unit 6 is narrower than the interval between the pair of electrodes 13 and 14 in the third photodetecting unit 5. A current change rate adjustment method such as.

Further, in the embodiment shown in FIG. 14, it has been mentioned that the difference in current change rate is caused by the difference in the material of the photosensitive film 8. As described above, since the material of the photosensitive film 8 affects the rate of change in current, the electrodes 9, 10, 13 and 14 for the first and third light detection units 3 and 5 are located. The material is changed between the photosensitive film 8 in the part and the photosensitive film 8 in the part where the electrodes 11, 12, 15 and 16 for the second and fourth light detection units 4 and 6 are located. Thus, an embodiment in which a difference in current change rate is caused is also possible. In the above description, as the material of the photosensitive film 8, when detecting ultraviolet rays, when detecting visible light such as ZnO, In ₂ O ₃ , SnO ₂ having a band gap of about 3.2 eV, the band is used. Amorphous Si having a gap of about 1.7 eV is exemplified, but two of these are selected as appropriate, one of them is used in the first and third light detection units 3 and 5, and the other is used in the second and fourth. By using them in the light detection units 4 and 6, a difference in current change rate may be generated.

  When a material having a crystal structure is used as the material of the photosensitive film 8, the state of the crystal grain boundary of the photosensitive film 8 in the first and third light detection units 3 and 5, and the second and fourth The difference in current change rate may be generated by making the state of the crystal grain boundary of the photosensitive film in the photodetecting sections 4 and 6 different.

  In the present invention, in order to further increase the difference in current change rate between the first and third light detection units 3 and 5 and the second and fourth light detection units 4 and 6, the current as described above is used. The change rate adjustment methods can be appropriately combined and employed.

  Moreover, although the light detection part comprised by one pair of electrodes was shown, you may provide two or more pairs of electrodes in each light detection part.

1, 1a, 1b Photosensor element 2 Substrate 3 First light detector 4 Second light detector 5 Third light detector 6 Fourth light detector 8 Photosensitive film 9-16 Electrode 17 First Connection unit 18 Second connection unit 19 Third connection unit 20 Fourth connection unit 21 First terminal 22 Second terminal 23 Third terminal 24 Fourth terminal 25 Fixed voltage source 26 Voltmeters 49 and 50 Laser light

Claims (11)

A substrate,
A first to a fourth photodetecting section each comprising a photoconductive film having photoconductivity formed on the substrate and at least one pair of electrodes in contact with the photosensitive film;
With
A bridge circuit is configured by the first to fourth light detection units,
The first light detection unit and the second light detection unit are electrically connected via a first connection unit,
The second light detection unit and the third light detection unit are electrically connected via a second connection unit,
The third light detection unit and the fourth light detection unit are electrically connected via a third connection unit,
The fourth light detection unit and the first light detection unit are electrically connected via a fourth connection unit,
In the first connection portion, a first terminal is provided,
In the second connection portion, a second terminal is provided,
In the third connection portion, a third terminal is provided,
In the fourth connection portion, a fourth terminal is provided,
The rate of change of the output current with respect to the illuminance of the irradiated light (hereinafter referred to as “current rate of change”) differs between the first light detection unit and the second light detection unit, and the third. Different between the light detection unit and the fourth light detection unit,
Optical sensor element.   The current change rate of the first light detection unit and the current change rate of the third light detection unit are substantially equal, and the current change rate of the second light detection unit and the fourth light detection The optical sensor element according to claim 1, wherein a current change rate of the portion is substantially equal.   The distance between the pair of electrodes in the first light detection unit is different from the distance between the pair of electrodes in the second light detection unit, and the pair of electrodes in the third light detection unit The optical sensor element according to claim 1, wherein an interval between the electrodes and a distance between the pair of electrodes in the fourth light detection unit are different.   The material of the light sensitive film in the first light detecting unit is different from the material of the light sensitive film in the second light detecting unit, and the material of the light sensitive film in the third light detecting unit is different from the material of the light sensitive film. 4. The optical sensor element according to claim 1, wherein a material of the light-sensitive film in the light detection unit of 4 is different.   The photosensitive film includes an oxygen element, and a density of oxygen defects in the photosensitive film between the pair of electrodes in the first light detection unit and a distance between the pair of electrodes in the second light detection unit. The density of oxygen defects in the photosensitive film is different from the density of oxygen defects in the photosensitive film between the pair of electrodes in the third photodetecting section and the density in the fourth photodetecting section. The optical sensor element according to claim 1, wherein the density of oxygen defects in the photosensitive film between a pair of electrodes is different.   The optical sensor element according to claim 5, wherein at least the electrodes in the first and third light detection units or at least the electrodes in the second and fourth light detection units include Ti.   By measuring the potential difference between the first and third terminals while applying a driving voltage between the second and fourth terminals using the optical sensor element according to any one of claims 1 to 6. An illuminance detection method for obtaining an illuminance of light applied to the optical sensor element. A method for producing the photosensor element according to any one of claims 1 to 6,
Preparing the substrate;
Forming the first to fourth light detectors on the substrate;
Prepared,
The step of forming the light detection unit includes the step of forming the photosensitive film and the step of forming the electrode.
Further, after the step of forming the electrode, the method includes a step of heat-treating the light detection unit in order to adjust a relationship between current change rates of the first to fourth light detection units.
A method for manufacturing an optical sensor element. The step of forming the electrodes includes a first electrode forming step of forming the electrodes constituting the second and fourth photodetecting portions, and forming the electrodes constituting the first and third photodetecting portions. And a second electrode forming step.
The step of heat-treating the photodetecting portion includes a first heat-treating portion of the photodetecting portion provided by the electrode formed in the electrode forming step performed first in the first electrode forming step and the second electrode forming step. A heat treatment step, and a second heat treatment step for heat-treating the light detection portion provided by the electrode formed in the electrode formation step performed later,
The first heat treatment step is performed between the first electrode formation step and the second electrode formation step,
The heat treatment temperature applied in the first heat treatment step is higher than the heat treatment temperature applied in the second heat treatment step,
The manufacturing method of the optical sensor element of Claim 8. The step of heat-treating the light detector includes a first irradiation step of irradiating the second and fourth light detectors with laser light, and a second of irradiating the first and third light detectors with laser light. An irradiation process,
The intensity of the laser beam irradiated in the first irradiation step is different from the intensity of the laser beam irradiated in the second irradiation step.
The manufacturing method of the optical sensor element of Claim 8. The step of forming the electrode includes the step of forming the electrodes for the second and fourth light detection units or the first and third light detection units on the substrate before the step of forming the photosensitive film. And the step of forming the photosensitive film, the electrodes for the first and third light detection units or the second and fourth light detection units are formed on the photosensitive film. Forming, and
The step of heat-treating the light detection unit is performed at once on the first to fourth light detection units.
The manufacturing method of the optical sensor element of Claim 8.

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