JP2013253896A - Photo detector, camera, and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photo detector, a camera, and an electronic apparatus which have high sensitivity to a designed absorption wavelength.SOLUTION: A photo detector 20 includes a first absorption film 2 disposed on a support substrate 1 and absorbing infrared rays and a terahertz wave, a detector 4 disposed on the support substrate 1 and connected to the first absorption film 2, a support leg 5 supporting the support substrate 1, and a second absorption film 3 disposed on the support leg 5 and absorbing infrared rays and a terahertz wave.

Description

  The present invention relates to a light detection element, a camera, and an electronic device.

A terahertz wave is an electromagnetic wave having a wavelength close to infrared. The image measurement technology using terahertz waves has been studied for use in various fields. For example, there are a specific substance detection device using a terahertz camera, determination of counterfeit bills, detection of chemicals in envelopes, non-destructive inspection of buildings, and the like.
On the other hand, as an infrared camera, there is a camera using an infrared detection element. Since the wavelength of the terahertz wave is close to infrared rays, the applicant has invented a technology that uses an infrared detection element for the terahertz wave detection element.
Conventionally, for example, as described in Patent Document 1, a bolometer-type infrared detection element in which a detection unit is formed on a support substrate and the support substrate has a hollow structure has been known. In this example, the absorption part is provided on the bolometer which hits the detection part. Infrared rays are converted into heat by the absorption unit, and the detection unit is warmed by this heat. And it is functioning as an infrared detection element (detection element) by reading the resistance temperature change of a detection part.

  In order to increase the signal sensitivity of the infrared detection element, it is required that the temperature change of the detection unit increases. For this reason, in order to make the detection part easy to warm, a device for improving thermal separation is devised by forming a thermal separation cavity under the detection element and supporting it with a support leg including electric wiring. .

  Furthermore, by vacuum-sealing the detection element in the package, the heat in and out of the detection element is dominated by the support legs. For this reason, in order to reduce the thermal conductance of the support legs, the support legs are required to be as long as possible while maintaining the strength to support the support substrate. In the conventional example, by bending the support leg, the support leg is lengthened while keeping the element size compact.

  For the absorption part on the detection part, it is necessary to use a material and a structure having good infrared absorption characteristics in order to increase the amount of infrared absorption. For example, in Patent Document 1, an improvement is made by absorbing a wide infrared wavelength band by laminating absorption films having different absorption characteristics. Furthermore, a reflective film is placed under the absorption film, and the distance between the absorption film and the reflective film is set to ¼ times the infrared wavelength for which sensitivity is to be increased, thereby causing optical interference and increasing the infrared absorption rate. More is being done. This makes it possible to have sensitivity over a wide range over the filter transmission wavelength band centering on the targeted wavelength band.

JP 2006-226890 A

  However, in the infrared detection element described in Patent Document 1, in order to reduce the thermal conductance of the support leg, the support leg is elongated and bent many times. For this reason, the supporting leg is easily bent. In addition, it is difficult to control the optical distance between the absorption film and the reflection film due to internal stress in the laminated film, additional stress during the process, and the weight of the detection element itself. As a result, the absorptance with respect to the infrared ray of the target wavelength is reduced, and further, the absorbed heat escapes from the support legs, so that the temperature rise of the detection unit is reduced, and the sensitivity to the designed absorption wavelength is reduced. There was a problem. Therefore, in order to realize a highly sensitive photodetection element, a photodetection element that can prevent a decrease in infrared and terahertz wave sensitivity due to heat escape from the support leg has been desired.

  The present invention has been made for the purpose of improving the reduction in sensitivity of infrared rays and terahertz waves due to heat escape from the support legs, and can be realized as the following forms or application examples.

  Application Example 1 A light detection element according to this application example is disposed on a support substrate, and is connected to a first absorption unit that absorbs infrared rays and terahertz waves, and is connected to the first absorption unit to detect a temperature change. It comprises a detection unit, a support leg that supports the support substrate, and a second absorption unit that is at least partially disposed on the support leg and absorbs infrared rays and terahertz waves.

  According to this application example, the light detection element includes the support substrate, and the first absorption unit that absorbs infrared rays and terahertz waves is disposed on the support substrate. And the 1st absorption part is converted into heat by absorbing infrared rays and terahertz waves. The light detection element includes a detection unit, and the detection unit detects a temperature change of the detection unit itself due to heat transmitted from the first absorption unit. There is a correlation between the amount of light irradiation and the temperature change of the detection unit. Therefore, the light detection element can estimate the irradiation amount of infrared rays or terahertz waves by detecting the temperature change of the detection unit due to the heat transmitted from the first absorption unit.

  Infrared rays or terahertz waves applied to the light detection element are converted into heat by the first absorption unit and the second absorption unit. Among these, the heat generated in the first absorption unit is conducted to the detection unit and the support substrate connected to the first absorption unit. And a temperature rise occurs in each place. In parallel, the heat generated in the second absorption part raises the temperature of the support legs. The heat transmitted to the support substrate tends to escape out of the element through the support legs. However, since the temperature rises in the support legs, the speed of heat escape becomes slow due to Fourier's law, and in the detection part, the width of the temperature rise increases with respect to the irradiation amount of infrared rays and terahertz waves, and the detection sensitivity Becomes higher. As a result, it is possible to improve the decrease in sensitivity of infrared rays and terahertz waves due to heat escaping from the support legs.

  Application Example 2 In the light detection element according to the application example described above, it is preferable that the area of the second absorption portion is smaller than the area of the first absorption portion.

  According to this application example, the amount of heat absorbed by the second absorption unit is smaller than the amount of heat absorbed by the first absorption unit. For this reason, the amount by which the heat generated in the second absorption part warms the detection part through the support leg and the support substrate and the temperature of the detection part rises becomes small. Therefore, it is possible to prevent the heat itself absorbed by the second absorption part from affecting the temperature rise of the detection part.

  Application Example 3 In the light detection element according to the application example described above, the sum of the heat capacities of the second absorption unit and the support leg is a heat capacity of the support substrate, the first absorption unit, and the detection unit. Is preferably smaller than the sum of.

  According to this application example, by reducing the sum of the heat capacities of the second absorption part and the support leg, the temperature increase between the second absorption part and the support leg can be reduced even with a small amount of heat absorbed by the second absorption part. The width can be increased. Thereby, the speed at which the heat conducted from the first absorption part and the detection part escapes to the outside through the support leg can be reduced. Thereby, since the temperature rise of a detection part becomes easy to occur, the detection sensitivity of a photon detection element can be made high.

  Application Example 4 In the light detection element according to the application example described above, the width of the absorption wavelength band in the light absorption spectrum of the second absorption unit is the absorption wavelength band in the light absorption spectrum of the first absorption unit. It is preferable that it is narrower than the width. The absorption wavelength band here indicates a wavelength band having an absorption rate of 50% or more with respect to the absorption rate of the maximum absorption wavelength.

  According to this application example, since the absorption wavelength band of the first absorption unit is wide, it has a characteristic of absorbing with respect to a wide range of light wavelengths. For this reason, the 1st absorption part can increase the light quantity which absorbs, and can expand the range of the temperature rise of a detection part. On the other hand, since the absorption wavelength band of the second absorption unit is narrow, when light of a specific wavelength band is incident, the second absorption unit absorbs a smaller amount of light than the light amount absorbed by the first absorption unit. Accordingly, it is possible to generate an amount of heat that prevents diffusion of heat from the support legs. As a result, the speed of heat escape from the support legs can be delayed to increase the width of the temperature rise of the detection unit.

  Application Example 5 An electronic apparatus according to this application example includes the camera described in the application example.

  Application Example 6 An electronic apparatus according to this application example includes the light detection element described in the application example.

FIG. 3 is a schematic top view showing the structure of the infrared detection element according to the first embodiment. The schematic cross section which shows the structure of an infrared rays detection element. The principal part schematic cross section which shows the structure of a detection part. The graph which shows the absorption spectrum of a 1st absorption film. The graph which shows the absorption spectrum of a 2nd absorption film. The schematic diagram for demonstrating the manufacturing method of an infrared rays detection element. The schematic diagram for demonstrating the manufacturing method of an infrared rays detection element. The schematic diagram for demonstrating the manufacturing method of an infrared rays detection element. The figure for demonstrating the temperature distribution of an infrared detection element. The figure for demonstrating the signal which an infrared detection element outputs. The schematic top view which shows the structure of the infrared rays detection element concerning the modification 1. It is a figure which shows the camera which is one Embodiment of the electronic device which concerns on this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the scale of each layer and each member is made different from the actual scale so that each layer and each member can be recognized.

(Embodiment 1)
FIG. 1 is a schematic top view illustrating the structure of the photodetecting element according to the first embodiment. FIG. 2 is a schematic cross-sectional view showing the structure of the photodetecting element, and is a schematic cross-sectional view taken along the line YY ′ in FIG. FIG. 3 is a schematic cross-sectional view of a main part showing the configuration of the detection unit.
In the present embodiment, a plurality of photodetecting elements 20 shown in FIG. 1 are arranged in a matrix to form an array sensor. This array sensor is packaged in a vacuum, and an optical filter that selectively passes infrared rays of 5 μm to 14 μm is mounted on the infrared incident surface. Here, a schematic configuration of a single element of the photodetecting elements constituting the array sensor will be described.

As shown in FIGS. 1 and 2, the light detection element 20 includes a square plate-like support substrate 1. The support substrate 1 is supported by a pair of support legs 5. A detection unit 4 is installed on the support substrate 1, and an interlayer insulating film 12, an electrical wiring 7, a protective film 13, and the like are stacked on the upper surface of the detection unit 4. On the upper surface of the protective film 13, a first absorption film 2 serving as a first absorption section is installed at a position overlapping the detection section 4 in plan view so as to cover the detection section 4.
On the upper surface of the support leg 5, an electrical wiring 7, a protective film 13, and the like are laminated. On the upper surface of the protective film 13, a second absorption film 3 as a second absorption portion is installed at a position overlapping a part of the support leg 5 in plan view. The first absorption film 2 and the second absorption film 3 are films that absorb infrared rays. The detection unit 4 is connected to the first absorption film 2 and has a function of detecting a temperature change.

  The area of the second absorption film 3 is set smaller than the area of the first absorption film 2. The amount of heat absorbed by the second absorption film 3 is smaller than the amount of heat absorbed by the first absorption film 2. For this reason, the amount of heat generated in the second absorption film 3 that causes the temperature of the detection unit 4 to rise by heating the detection unit 4 through the support legs 5 and the support substrate 1 is reduced. Therefore, it is possible to prevent the heat of the second absorption film 3 from affecting the temperature detected by the detection unit 4.

  The support substrate 1 and the support legs 5 are configured by stacking a silicon oxide film and a silicon nitride film. As shown in FIG. 3, the detection unit 4 has a pyroelectric capacitor structure in which a pyroelectric material 15 such as lead zirconate titanate (PZT) is sandwiched between an upper electrode 14 and a lower electrode 16 made of platinum.

  Returning to FIG. 1 and FIG. 2, a pair of electrical wirings 7 are arranged on the support substrate 1 and the support legs 5. The upper electrode 14 and the lower electrode 16 of the detection unit 4 are connected to different electric wires 7 of the pair of electric wires 7. The pair of electric wires 7 are electrically connected to a detection circuit (not shown) through the support leg 5. Then, the electrical signal generated in the detection unit 4 is output to the detection circuit. It is preferable to prevent heat from escaping from the electrical wiring 7 on the support leg 5 to the outside of the light detection element 20. For this reason, the material of the electrical wiring 7 may be any material that can easily conduct electricity and has relatively low thermal conductivity. In the present embodiment, for example, Ti and TiN are used. The electrical wiring 7 employs a wiring having a laminated structure of Ti and TiN.

  As shown in FIG. 2, the light detection element 20 includes a substrate 10, and an interlayer film 8 is provided on the substrate 10. A laminated film 17 is installed on the interlayer film 8, and the laminated film 17 is connected to the support legs 5. The interlayer film 8 is provided with a recess 8 a at a position facing the support substrate 1, and a heat separation cavity 6 is formed by the recess 8 a. The support substrate 1 is located on the heat separation cavity 6, and the support substrate 1 is supported in a hollow state by the support legs 5. By providing the thermal separation cavity 6 under the detection unit 4, the detection unit 4 is thermally separated from the surroundings. A stopper film 9 for protecting the interlayer film 8 is formed when the thermal separation cavity 6 is formed. The stopper film 9 is made of an alumina film that is resistant to etching in a hydrogen fluoride (HF) vapor process.

  The support substrate 1 and the first absorption film 2 above the detection unit 4 are formed of a laminated film of a silicon oxide film and a silicon nitride film. The support leg 5 has a bent portion 5a partially bent at a right angle. The second absorption film 3 disposed above the support leg 5 is made of a silicon oxide film. By disposing the second absorption film 3 on the bent portion 5a, there is an effect of increasing the rigidity of the support leg 5 and reducing the deformation of the bent portion 5a where stress concentration easily occurs. However, the second absorption film 3 does not necessarily have to be on the bent portion 5a, and may be arranged on a straight line of the support leg 5.

  FIG. 4 is a graph showing an absorption spectrum of the first absorption film. As shown in FIG. 4, the first absorption film 2 has a laminated structure of a silicon oxide film and a silicon nitride film, thereby having a wide absorption wavelength band for infrared rays of 8 μm to 14 μm. FIG. 5 is a graph showing an absorption spectrum of the second absorption film. As shown in FIG. 5, the second absorption film 3 is a silicon oxide film and has a sharp absorption peak in the vicinity of 10 μm.

  The width of the absorption wavelength band of the second absorption film 3 is narrower than the width of the absorption wavelength band of the first absorption film 2. For this reason, the first absorption film 2 can increase the amount of infrared rays to be absorbed, and can widen the width of the wavelength band involved in the temperature rise of the detection unit 4. On the other hand, since the absorption wavelength band of the second absorption film 3 is narrow, when an infrared ray of a specific wavelength band is incident, the infrared ray is absorbed in an amount smaller than the amount of infrared ray absorbed by the first absorption film 2. Accordingly, it is possible to generate an amount of heat that hinders the diffusion of heat from the support legs 5. As a result, the speed at which heat escapes from the support legs 5 can be delayed, and the temperature rise of the detection unit 4 can be increased.

  In the light detection element 20, the sum of the heat capacities of the second absorption film 3 and the support legs 5 is set to be smaller than the sum of the heat capacities of the support substrate 1, the first absorption film 2, and the detection unit 4. By reducing the sum of the heat capacities of the second absorption film 3 and the support legs 5, the width of the temperature increase between the second absorption film 3 and the support legs 5 can be increased even with a small amount of heat transmitted from the second absorption film 3. can do. Thereby, the speed which the heat transmitted from the 1st absorption film 2 and the detection part 4 escapes outside through the support leg 5 can be delayed. Therefore, since the temperature of the detection unit 4 is likely to increase, the detection sensitivity of the light detection element 20 can be increased.

Next, a method for manufacturing the photodetecting element 20 will be described. 6 to 8 are schematic views for explaining a method of manufacturing the photodetecting element. FIG. 6 shows a stage before the support substrate 1 and the support legs 5 are formed.
As shown in FIG. 6, an interlayer film 8 is formed on the substrate 10. Then, a recess 8 a is formed in a portion of the interlayer film 8 where the thermal separation cavity 6 is to be formed, and a stopper film 9 is formed on the interlayer film 8. Then, a sacrificial layer 11 made of a silicon oxide film is formed above the recess 8a. The sacrificial layer 11 is formed by CVD (Chemical-Vapor-Deposition) or the like, and is planarized by a technique such as CMP (Chemical-Mechanical-Polishing). Although the stopper film 9 is also formed on the sacrificial layer 11, the following description will be made with the stopper film 9 omitted to simplify the description.

Next, a laminated film 17 is formed above the interlayer film 8 and the sacrificial layer 11. The laminated film 17 is a film on which the support substrate 1 and the support legs 5 are formed. The detection unit 4 is formed on the laminated film 17, and the interlayer insulating film 12 made of a silicon oxide film is formed on the detection unit 4.
Next, a hole is opened in the interlayer insulating film 12 in order to establish electrical connection with the lower electrode 16 and the upper electrode 14 of the detection unit 4.
Thereafter, the electrical wiring 7 is formed. Thereby, the electrical wiring 7 is connected to the lower electrode 16 and the upper electrode 14 through the holes.
Next, after the protective film 13 made of a silicon oxide film is formed so as to cover the entire elements such as the electric wiring 7, the interlayer insulating film 12, and the laminated film 17, Then, the portion of the protective film 13 where the support substrate 1 and the support legs 5 are to be formed later is removed. These can be formed by using a photolithography technique.

  Next, as shown in FIG. 7, a laminated film of a silicon oxide film and a silicon nitride film constituting the first absorption film 2 is formed on the detection unit 4, and patterning of the laminated film is performed. Thereby, the first absorption film 2 is formed. Thereafter, a silicon oxide film constituting the second absorption film 2 is formed on the electric wiring 7, and patterning of the silicon oxide film is performed. At this time, since the film structures of the first absorption film 2 and the second absorption film 3 are different, a difference occurs in the infrared absorption rate.

  Next, as shown in FIG. 8, patterning of the laminated film 17 on the sacrificial layer 11 is performed to form the support legs 5 and the support substrate 1. Next, an alumina film that covers the entire photodetecting element 20 and serves as the stopper film 9 in the process of forming the thermal separation cavity 6 is formed. Then, the stopper film 9 on the sacrificial layer 11 is removed by patterning the stopper film 9. Finally, only the sacrificial layer 11 is selectively etched by HF vapor treatment to create the thermal separation cavity 6.

  Next, the operation of the above-described photodetecting element of this embodiment will be described. FIG. 9 is a graph for explaining the temperature distribution of the photodetecting element, and is a graph showing the temperature measured at the Z-Z ′ line cross section of the plan view in the drawing. FIG. 10 is a diagram for explaining a signal output from the light detection element.

  When the photodetector 20 is irradiated with infrared rays having a wavelength band different from the absorption peak (10 μm) of the second absorption film 3 in the range of 8 μm to 14 μm, the first absorption film having a wide absorption wavelength band In 2, some infrared rays are absorbed. On the other hand, since the second absorption film 3 is out of the absorption wavelength band, the infrared absorption is small, and the temperature rise of the support leg 5 is only slight. In this case, since the influence on the diffusion of heat from the support leg 5 to the outside of the light detection element 20 is small, the heat absorbed by the first absorption film 2 is to some extent as in the case where the second absorption film 3 is not provided. The detection unit 4 is warmed up to.

The temperature distribution in the photodetecting element 20 at this time is indicated by a first temperature distribution line 21 in FIG. The temperature between BCs corresponding to the place of the support substrate 1 on which the detection unit 4 is placed is the highest, and the temperature of the support leg 5 decreases as the distance from the support substrate 1 along the support leg 5 increases.
The signal output of the detection unit 4 due to the pyroelectric effect is indicated by a first output transition line 22 in FIG. When the light detection element 20 is irradiated with infrared rays, a signal output is output from the electrical wiring 7 and the sensor output value increases. However, since the signal output due to the pyroelectric effect is observed only when there is a change in temperature of the pyroelectric body, if the infrared ray is continuously irradiated, the heat detection and heat dissipation to the light detection element 20 causes the inside of the infrared detection element 20 to be radiated. At this point, the thermal equilibrium is reached and no signal is observed thereafter.

  When the light detection element 20 is irradiated with infrared rays having a wavelength band around the absorption peak (10 μm) of the second absorption film 3, the first absorption film 2 having a wide absorption wavelength band is similar to the above. Absorption occurs. On the other hand, heat absorption also occurs in the second absorption film 3 having an absorption peak in this wavelength band. The temperature distribution in the photodetecting element 20 at this time is indicated by a second temperature distribution line 23 in FIG.

  Compared to the first temperature distribution line 21, the temperature of the support leg 5 rises as indicated by the second temperature distribution line 23. As a result, the temperature difference between the support substrate 1 including the detection unit 4 and the support leg 5 is reduced, and the diffusion of heat from the support substrate 1 including the detection unit 4 to the support leg 5 is suppressed by Fourier's law. The temperature increase width of the portion 4 is increased. The signal output of the detection unit 4 at this time is indicated by a second output transition line 24 in FIG. The sensor output of the second output transition line 24 increases compared to the first output transition line 22.

  In order to delay the speed at which heat escapes from the support leg 5 when irradiated with an infrared ray of a specific wavelength, a particularly high sensitivity is obtained for the designed wavelength while having sensitivity over the infrared absorption wavelength band. be able to.

As described above, this embodiment has the following effects.
(1) According to this embodiment, the infrared rays irradiated on the light detection element 20 are converted into heat by the first absorption film 2 and the second absorption film 3. The heat transmitted to the support substrate 1 tends to escape outside the light detection element 20 through the support legs 5. However, the temperature rises in the support leg 5, and the speed at which heat escapes is delayed by Fourier's law. Thereby, in the detection part 4, the width | variety of temperature rise with respect to the irradiation amount of infrared rays becomes large, and detection sensitivity becomes high. As a result, it is possible to improve a decrease in infrared sensitivity due to heat escape from the support leg 5.

  (2) According to this embodiment, the area of the second absorption film 3 is smaller than the area of the first absorption film 2. Therefore, the heat of the second absorption film 3 itself can be prevented from affecting the temperature change detected by the detection unit 4.

  (3) According to this embodiment, the sum of the heat capacities of the second absorption film 3 and the support legs 5 is smaller than the sum of the heat capacities of the support substrate 1, the first absorption film 2, and the detection unit 4. Yes. Thereby, the width of the temperature rise between the second absorption film 3 and the support leg 5 can be increased even with a small amount of heat transmitted from the second absorption film 3. Thereby, the speed which the heat transmitted from the 1st absorption film 2 and the detection part 4 escapes outside through the support leg 5 can be delayed. Therefore, since the temperature of the detection unit 4 is likely to increase, the detection sensitivity of the light detection element 20 can be increased.

  (4) According to this embodiment, the width of the absorption wavelength band in the infrared absorption spectrum of the second absorption film 3 is narrower than the width of the absorption wavelength band in the infrared absorption spectrum of the first absorption film 2. Therefore, the second absorption film 3 can generate a quantity of heat that hinders the diffusion of heat from the support legs 5. As a result, the speed at which the heat from the support legs 5 escapes can be delayed, and the width of the temperature rise of the detection unit 4 can be increased.

  The above-described embodiment is an example in which the absorption wavelength is designed to be optimal with infrared rays. However, by designing the absorption wavelength to be a terahertz wave whose wavelength band is close to infrared rays, it can be used as a terahertz wave detection element. In addition, this invention is not limited to embodiment mentioned above, A various change, improvement, etc. can be added to embodiment mentioned above. A modification will be described below. In the modified example, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted or simplified here.

(Modification 1)
FIG. 11 is a schematic top view illustrating the structure of the light detection element according to the first modification. In the first embodiment, the two support legs 5 are installed diagonally from the support substrate 1, but the present invention is not limited to this configuration. Hereinafter, Modification 1 will be described.

  In the first modification, the light detection element 27 includes the support substrate 1, and the support substrate 1 is supported by one support leg 28. Here, the length of the support leg 28 is the same as that of the first embodiment. The width of the support leg 28 may be thicker than the support leg 5 shown in the first embodiment, but is smaller than twice. The two wires connected to the upper electrode 14 and the lower electrode 16 of the detection unit 4 pass on the same support leg 28. The second absorption film 3 is disposed on the support leg 28, and the area thereof is equivalent to the area of the second absorption part 3 shown in the first embodiment.

  According to the light detection element 27 of the first modification, in addition to the effects of the first embodiment, the total number of support legs 28 is reduced, so that the total thermal conductance is reduced as compared with the first embodiment. For this reason, the temperature rise width of the detection part 4 becomes large, and the output of a signal can be enlarged. As a result, the sensitivity of the light detection element 27 can be increased.

(Modification 2)
In the first embodiment, the second absorption film 3 is installed on the support leg 5. However, the second absorption film 3 may be installed on the support substrate 1 in addition to the support leg 5. Moreover, you may design according to the heat distribution of a photon detection element. Furthermore, the second absorption film 3 may be provided on the laminated film 17 on the interlayer film 8. By disposing the second absorption film 3 at an appropriate position, the speed at which the heat of the support substrate 1 escapes can be further reduced.

  FIG. 13 shows an example of a terahertz camera as an electronic device including the light detection element of this embodiment. An example in which the terahertz camera 1000 is configured in combination with a terahertz wave irradiation unit, in which the absorption wavelength of the above-described light detection element is set to be optimal with a terahertz wave, is shown.

  A terahertz camera 1000 as an electronic device includes a control unit 1010, an irradiation light unit 1020, an optical filter 1030, an imaging unit 1040, and a display unit 1050. The imaging unit 1040 includes an optical system such as a lens (not shown) and a sensor device that optimizes the absorption wavelength of the first absorption film of the above-described infrared detection element in the terahertz range.

The control unit 1010 includes a system controller that controls the entire apparatus, and the system controller controls the light source driving unit and the image processing unit included in the control unit 1010.
The irradiation light unit 1020 includes a laser device that emits a terahertz wave (an electromagnetic wave having a wavelength in the range of 100 μm to 1000 μm) and an optical system, and irradiates the person 1060 to be inspected with the terahertz wave.
The reflected terahertz wave from the person 1060 is received by the imaging unit 1040 through the optical filter 1030 that allows only the spectral spectrum of the specific substance 1070 to be detected to pass.
The image signal generated by the imaging unit 1040 is subjected to predetermined image processing by the image processing unit of the control unit 1010, and the image signal is output to the display unit 1050. The presence of the specific substance 1070 can be determined because the intensity of the received light signal varies depending on whether or not the specific substance 1070 is present in the clothes of the person 1060.

  Although several embodiments have been described above, it is easily understood by those skilled in the art that many modifications can be made without substantially departing from the novel matters and effects of the present invention. Accordingly, all such modifications are intended to be included in the scope of the present invention. For example, a term described at least once together with a different term having a broader meaning or the same meaning in the specification or the drawings can be replaced with the different term in any part of the specification or the drawings.

  The present invention can be widely applied to various photodetectors, cameras, and electronic devices. Note that the wavelength of the electromagnetic wave to be detected is an effective technique particularly in the case of infrared rays or terahertz waves.

  DESCRIPTION OF SYMBOLS 1 ... Support substrate, 2 ... 1st absorption film as 1st absorption part, 3 ... 2nd absorption film as 2nd absorption part, 4 ... Detection part, 5 ... Support leg, 20, 27 ... Light Detection element.

Claims (6)

A first absorber disposed on the support substrate and absorbing infrared and terahertz waves;
A detection unit connected to the first absorption unit to detect a temperature change;
A support leg for supporting the support substrate;
A second absorption part that is at least partially disposed on the support leg and absorbs infrared rays and terahertz waves;
A photodetecting element comprising: The photodetecting element according to claim 1,
The area of the second absorption part is smaller than the area of the first absorption part. The photodetecting element according to claim 2,
The light detection element, wherein a sum of heat capacities of the second absorption part and the support leg is smaller than a sum of heat capacities of the support substrate, the first absorption part, and the detection part. The photodetecting element according to any one of claims 1 to 3,
The width of the absorption wavelength band in the light absorption spectrum of the second absorber is
An optical detection element characterized by being narrower than the width of an absorption wavelength band in the light absorption spectrum of the first absorption part.   A camera comprising the light detection element according to claim 1.   An electronic apparatus comprising the light detection element according to claim 1.

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