JP2016050833A - Infrared sensor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To downsize an infrared sensor device with which it is possible to detect light from a plurality of different fields of vision separately.SOLUTION: Light-receiving parts 50a, 50b equipped with a light-receiving element having a mesh-shaped compound semiconductor laminate part 20 that includes a PN-junction part or a photodiode structure such as the PN-junction part, etc., and an infrared shielding part 30 covering a portion of the compound semiconductor laminate part 20 are provided on the same board 10, and the side faces 40a, 40b as the principal incident surfaces of the light-receiving parts 50a, 50b are formed so as to be non-parallel between the light-receiving parts 50a and 50b. As the fields of vision of the light-receiving parts 50a, 50b that are determined by the side faces 40a, 40b as the principal incident surfaces are different, infrared rays from different fields of vision can be detected separately. Since external components, etc., do not need to be provided, the infrared sensor device with which it is possible to detect light from a plurality of different fields of vision separately can be downsized.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an infrared sensor device, and more particularly to an infrared sensor device including a plurality of light receiving units having different fields of view.

In general, the body temperature of the human body is around 36 degrees, and the human body emits infrared rays in a wide range of radiation from 2 μm to 30 μm. By detecting this light, the position or movement of the human body can be detected.
A pyroelectric sensor and a thermopile are mentioned as an example of the sensor which operate | moves in said wavelength range of 2 micrometers or more and 30 micrometers or less. In order to increase the sensitivity of these sensors, it is necessary to provide a hollow region between the light receiving portion and the light incident window portion, which makes it difficult to reduce the size of these sensors.

  As another sensor that operates in a wavelength band of 2 μm or more and 30 μm or less, a quantum type (photovoltaic type) infrared sensor is expected. The quantum infrared sensor is a PN junction formed by joining an n-type semiconductor whose majority carrier is an electron and a p-type semiconductor whose majority carrier is a hole, or a genuine semiconductor between a p-type semiconductor and an n-type semiconductor ( It has a PIN junction photodiode structure having an i-type semiconductor, a π-type semiconductor, or a ν-type semiconductor.

In a quantum infrared sensor, electron hole pairs generated in a depletion layer present in a PN junction or PIN junction by infrared photons are spatially separated and accumulated according to the valence band and conduction band inclinations. The n-type semiconductor is charged on the plus side and the n-type semiconductor is charged on the minus side, and an electromotive force is generated between them (for example, see Patent Document 1).
This electromotive force is called an open-circuit voltage, and can be read out as a voltage by using an external resistance (which may be a high input impedance circuit or amplifier) larger than the resistance of the PN junction or PIN junction, It is also possible to read out the current as a short circuit.

  By the way, when such an infrared sensor is used as a human sensor, an optical system using a complicated lens as shown in Patent Document 2, for example, is used to separate and detect light from a plurality of different fields of view. It becomes the provided device.

International Publication No. 2005-27228 Pamphlet JP2013-231667A

In an infrared sensor device provided with such a complicated optical system, the number of external components for the infrared sensor device increases, and there is a problem that the entire device is increased in size.
In addition, there is a problem that manufacturing variation in the assembly process increases due to external attachment.
The present invention has been made paying attention to this point, and can reduce the size without increasing the manufacturing variation, and can separately detect light from a plurality of different fields of view. An object of the present invention is to provide an infrared sensor device.

  An infrared sensor device according to an aspect of the present invention includes a light receiving element including a light receiving element having a polyhedral compound semiconductor stacked portion including a photodiode structure and an infrared shielding portion covering a part of the compound semiconductor stacked portion. A plurality of light receiving portions are provided on the substrate, and a main incident surface of the light receiving portion is non-parallel between the plurality of light receiving portions.

  According to the infrared sensor device of the present invention, light from a plurality of different fields of view can be separated and detected without using external parts or the like, that is, the infrared sensor device can be miniaturized.

It is sectional drawing of the schematic diagram which shows an example of the light-receiving part in the infrared sensor apparatus of this invention. It is a schematic diagram which shows an example of the infrared sensor in 1st Embodiment of this invention. It is a schematic diagram which shows an example of the infrared sensor in 2nd Embodiment of this invention. It is an equivalent circuit with which it uses for operation | movement description of the infrared sensor in 2nd Embodiment. It is a schematic diagram which shows an example of the infrared sensor in 3rd Embodiment of this invention. It is a schematic diagram which shows an example of the infrared sensor in 4th Embodiment of this invention. It is a characteristic view which shows an example of the output characteristic of the light-receiving part in the infrared sensor apparatus of this invention.

Hereinafter, a mode for carrying out the present invention (hereinafter referred to as this embodiment) will be described.
An infrared sensor device according to the present embodiment includes a photodiode structure having a PN junction or a PIN junction or the like, a light receiving element having a polyhedral compound semiconductor multilayer such as a mesa shape (frustum shape), and a compound semiconductor multilayer The infrared sensor device includes a plurality of light receiving units including an infrared shielding unit that covers a part of the unit on the same substrate, and a main incident surface of the light receiving unit is non-parallel between the plurality of light receiving units.

Since the main incident surface is non-parallel between the plurality of light receiving parts, the field of view determined by the orientation of the main incident surface differs between the plurality of light receiving parts, so that each light receiving part separates light from different fields of view. Equivalent to detecting. As a result, each light-receiving unit can separate and detect light from different fields of view without providing external components or the like.
Here, when the light receiving unit includes one light receiving element, among the planes of the compound semiconductor stacked portion included in the light receiving element, the one plane in which the region not covered by the infrared shielding unit is the largest is “main”. It becomes the “incident surface”.

In addition, among the flat surfaces of the compound semiconductor stacked portion included in one light receiving element, the light receiving portion has a plurality of light receiving elements connected in series, and one flat surface in which the region not covered by the infrared shielding portion is maximized When the light receiving elements are parallel to each other, one plane of the light receiving elements of the plurality of light receiving elements becomes the “main incident surface”.
In addition, among the flat surfaces of the compound semiconductor stacked portion included in one light receiving element, the light receiving portion includes a plurality of the light receiving elements connected in series, and the one surface that is not covered by the infrared shielding portion is the largest. Is non-parallel between any of the light receiving elements, that is, not parallel between the light receiving elements, the output of the light receiving part when a light source having a constant intensity is moved on a spherical surface equidistant from the center of the light receiving part. A surface perpendicular to a straight line connecting the center position of the light source and the center of the light receiving unit when the maximum value is defined as a “main incident surface”.

Note that the center of the light receiving unit represents the position of the point where the output signal of the light receiving unit becomes maximum when considering the case where light from the outside converges to a certain point.
FIG. 1 is a cross-sectional view of a schematic diagram showing an example of a light receiving unit 50 used in an infrared sensor device to which the present invention is applied.
As shown in FIG. 1, the light receiving unit 50 includes an n-type compound semiconductor layer 21, a light absorption layer (i-type semiconductor layer) 22, a barrier layer 24, and a p-type compound semiconductor layer 23 formed on the substrate 10. The compound semiconductor laminated part 20, the infrared shielding part 30, and the insulating layer 60 laminated | stacked in order are provided.

The compound semiconductor stacked unit 20 as a light receiving element is formed in a mesa shape, and is formed in a first mesa unit 201 including a PIN junction included in the compound semiconductor stacked unit 20 and a lower layer of the first mesa unit 201. And a second mesa unit 202 including the n-type compound semiconductor layer 21 included in the stacked unit 20.
The infrared shielding unit 30 is made of a metal material, and is disposed so as to cover the upper surface and the other three side surfaces without covering the side surface 40 of the compound semiconductor stacked unit 20. In the case of FIG. 1, the infrared shielding unit 30 is arranged via the insulating layer 60 so as to cover the three side surfaces except the upper surface and the side surface 40 in the first mesa unit 201. In addition, the infrared shielding portion 30 is also disposed on the second mesa portion 202 including the side surface 40 via the insulating layer 60. The infrared shielding portion 30 formed in the second mesa portion 202 on the side surface 40 side also functions as an electrode, that is, an output terminal 31. When the substrate 10 is a semi-insulating substrate, the two infrared shielding portions 30 shown in FIG. 1 are electrically connected by the internal region of the compound semiconductor stacked portion 20. That is, the second mesa unit 202 performs the element isolation function.
Next, each component of the infrared sensor device in the present embodiment will be described. Each description can be applied independently or in combination in the present embodiment (including more specific embodiments described later).

<Board>
In the infrared sensor device of the present embodiment, the substrate 10 serves as a base for forming a light receiving element. From the viewpoint of making each light receiving element electrically independent, the substrate 10 is preferably an insulating or semi-insulating substrate. Specific examples of the material of the substrate 10 include Si, GaAs, sapphire, InP, InAs, and Ge, but are not limited thereto.

From the viewpoint that a semi-insulating substrate can be produced and that the diameter can be increased, GaAs is a preferable material for the substrate.
Further, from the viewpoint of forming the compound semiconductor stacked unit 20 formed on the substrate with high quality, the lattice constant of the substrate 10 is preferably close to the lattice constant of the compound semiconductor stacked unit 20, particularly a layer in direct contact with the substrate. From the viewpoint of easily forming a layer containing indium (In) and antimony (Sb), which is a material of the compound semiconductor stacked portion 20 capable of detecting infrared rays, with high quality, GaAs is a preferable substrate material.

  Since the infrared sensor device of the present embodiment is configured to take infrared rays into the light receiving element from the first main surface 10a side of the substrate 10 on which the compound semiconductor stacked portion 20 is formed, the first main surface 10a of the substrate 10 is used. It is preferable to have a member that absorbs infrared rays or a member that reflects on the second main surface 10b side that is the opposite side of the surface. In the case of using a substrate material having low infrared transparency, it is not necessary to provide a member that absorbs infrared rays or a member that reflects infrared rays on the second main surface 10b side.

The material used for the member that reflects infrared rays may be any material as long as it reflects light efficiently, but from the viewpoint of ease of manufacturing process and good reflectivity, Al, Au, and Cr are used. Examples include alloys and laminated films. The member that reflects infrared rays may not be a metal material, and may be a material having a refractive index lower than that of the substrate. For example, when a GaAs or Si substrate is used, Si ₃ N ₄ , SiO ₂ , TiO ₂ or the like can be used. Since the refractive index of these non-metal layers is smaller than that of the substrate, it is preferable to use a conductive substrate because the back surface of the substrate can be electrically insulated while exhibiting a reflection effect.

  In addition, the infrared sensor of the present embodiment further includes an optical filter that can selectively transmit a specific wavelength band according to the wavelength of the infrared ray output from the detection target and the wavelength of the infrared ray that causes disturbance. May be. For example, when the object to be detected is a human body, it is preferable to use a filter that selectively transmits infrared light having a wavelength of 5 μm or more in order to improve discrimination from ambient light.

<Light receiver>
In the infrared sensor device of the present embodiment, the light receiving unit 50 includes a compound semiconductor stacked unit 20 and an infrared shielding unit 30 as light receiving elements.
The light receiving element may be a single light receiving element or a plurality of light receiving elements connected in series or in parallel. That is, each light receiving unit 50 may use a single light receiving element, or may be one in which a plurality of light receiving elements are connected. In the case where each light receiving unit 50 is constituted by two or more light receiving elements, it is preferable that the light receiving portions 50 are connected in series when the photovoltaic power is read as a current. In the case of voltage output, it is necessary to increase the voltage.

  In the case of current output, the S / N ratio is improved by increasing the resistance value and current value of the signal source. In the case of voltage output, the S / N ratio is improved by decreasing the resistance value of the signal source and increasing the voltage value. To do. The size and number of light receiving elements to be connected take into account the resistance value in the vertical direction (perpendicular to the substrate surface) per area of the PN junction, the voltage input conversion noise of the amplifier, and manufacturing restrictions (such as process rules). Thus, the optimization may be performed in order to realize the optimum S / N ratio. Of course, as the overall size of the light receiving unit 50 is increased, the optimized S / N ratio may be increased by adjusting the resistance value and current value or voltage value of the signal source. The number of light receiving parts (pixels) and the size of each light receiving part may be designed to be optimized in accordance with the optical system of the system.

<Light receiving element>
The light receiving element includes a mesa-shaped compound semiconductor stacked unit 20 having a PN junction or a PIN junction. As a material of the compound semiconductor laminated part 20, it can select and use from the material which can detect the infrared rays of a measuring object. A III-V group compound semiconductor is preferable, and includes at least one group III atom selected from the group consisting of indium (In), aluminum (Al), and gallium (Ga), antimony (Sb), and arsenic (As). More preferably, it is a compound semiconductor of at least one group V atom selected from the group consisting of Specific examples include InSb-based materials, InGaSb-based materials, InAlSb-based materials, InAsSb-based materials, and the like, which can be selected from materials that can detect infrared rays of a measurement object.

In the case of a light receiving element composed of an InSb-based material, a wavelength of 1 μm or more and 7 μm or less can be detected. In the case of a light receiving element composed of an InGaSb or InAlSb-based material, the detection range can be narrowed down to a wavelength band of 1 μm or more and 5 μm or less. In the case of a light receiving element made of an InAsSb-based material, a wavelength band of 1 μm to 12 μm can be detected.
As a method for forming the mesa-shaped compound semiconductor laminated portion 20, a known method can be employed. For example, the mesa-shaped compound semiconductor stacked portion 20 can be formed by forming each layer constituting the compound semiconductor stacked portion on the substrate and then etching a desired region through the mask pattern.

  The compound semiconductor stacked portion 20 of the infrared sensor device of the present embodiment is only required to be formed with at least one mesa shape, but may be a plurality of mesa shapes, that is, a multistage mesa shape as necessary. For example, as shown in FIG. 1, after compound semiconductors are stacked on a substrate in the order of n-type semiconductor layer / i-type semiconductor layer / p-type semiconductor layer, output terminals and electrodes ( The first mesa portion is further formed after the first mesa portion 201 is formed by etching a part of the compound semiconductor stacked portion for forming the first mesa portion 201 (including those for wiring) until the n-type compound semiconductor layer is exposed on the surface. The region surrounding 201 may be etched until the substrate is exposed on the surface to form the second mesa portion 202. In this case, the infrared shielding unit 30 only needs to cover at least a part of the first mesa unit 201. In the case of FIG. 1, the side surface of the first mesa portion (mesa portion including a PN junction portion or a PIN junction portion) 201 of the mesa-shaped (frustum-shaped) compound semiconductor stacked portion 20 is covered with the infrared shielding portion 30. It means the side with the highest ratio.

Since the field of view of each light receiving unit 50 of the infrared sensor device of the present embodiment is affected by the angle of the side surface of the compound semiconductor stacked unit 20, a mesa angle that provides a desired field of view may be appropriately formed depending on etching conditions and the like.
Hereinafter, a light receiving element having a PIN junction photodiode structure in which an n-type semiconductor layer / light absorption layer (i-type semiconductor layer) / p-type semiconductor layer are sequentially stacked on a substrate will be described as an example.

  When infrared light as light to be detected enters the photodiode structure, electron hole pairs generated in the depletion layer existing in the photodiode structure are spatially separated and accumulated according to the electric field gradient between the valence band and the conduction band. The As a result, the n-type compound semiconductor layer is charged on the negative side and the p-type compound semiconductor layer is charged on the positive side, thereby generating an electromotive force therebetween. This electromotive force is called an open-circuit voltage, and can be read as a voltage when connected to a signal processing circuit (such as an amplifier) having a high input impedance, or can be read as a current by short-circuiting outside the infrared sensor.

By performing high-concentration n-type doping, the n-type compound semiconductor layer shifts the infrared absorption wavelength of the n-type compound semiconductor layer to a shorter wavelength side due to an effect called a Barstein moss shift. Therefore, long-wavelength infrared rays are not absorbed, and infrared rays can be transmitted efficiently.
The light absorption layer is a light absorption layer for absorbing infrared rays and generating a photocurrent Ip. Therefore, the area where the n-type compound semiconductor layer and the light absorption layer are in contact with each other is the light receiving area on which infrared rays are incident. Generally, since the photocurrent Ip of the light receiving element increases in proportion to the light receiving area, it is preferable that the area where the n-type compound semiconductor layer and the light absorbing layer are in contact with each other is large. Moreover, since the amount of infrared rays that can be absorbed increases as the volume of the light absorption layer increases, the volume of the light absorption layer is preferably larger. The film thickness of the light absorption layer is preferably set to such a film thickness that electrons and hole carriers generated by infrared absorption can be diffused.

On the other hand, a semiconductor that absorbs infrared rays as used in the light absorption layer is generally a semiconductor having a small band gap, and such a semiconductor has a mobility of electrons much higher than a mobility of holes. For example, in the case of InSb, while the electron mobility is about 80,000cm ² / Vs, the mobility of holes is several hundred ^cm 2 / Vs. Therefore, the element resistance is greatly influenced by the ease of electron flow.

  Electrons generated by infrared absorption in the light absorption layer are diffused from the light absorption layer to the n-type compound semiconductor layer side due to the potential difference formed in the PN or PIN junction photodiode structure portion, and are taken out as a photocurrent. As described above, since a hole mobility is very small in a semiconductor having a small band gap, the electric resistance of the p-type doping layer is usually higher than that of the n-type doping layer. Further, the electrical resistance is inversely proportional to the area of the portion where the current flows. Therefore, the element resistance is determined by the size of the area where the light absorption layer and the p-type compound semiconductor layer are in contact, and it is preferable that the area is small in order to increase the element resistance.

The band gap of a semiconductor that can absorb infrared rays having a wavelength of 5 μm or more is as small as 0.25 eV or less. In such a semiconductor with a small band gap (semiconductor whose light absorption layer material has a band gap of 0.1 eV or more and 0.25 eV or less), the band gap is suppressed on the p-type compound semiconductor layer side in order to suppress diffusion current due to electrons. However, it is preferable to form a barrier layer larger than the light absorption layer because the leakage current of the element such as dark current is reduced and the element resistance can be increased.
The barrier layer is configured to have a larger band gap than the light absorption layer and the p-type compound semiconductor layer. Examples of the material constituting the barrier layer include AlInSb. By providing this barrier layer, the resistance of the light receiving portion increases, and therefore, when a signal is amplified by a current-voltage conversion amplifier, a high S / N ratio can be realized.

<Infrared shielding part>
The infrared shielding part 30 covers a part of the compound semiconductor multilayer part 20 of each light receiving element, and forms a side surface 40 that is not covered with the infrared shielding part 30 on any side face of the mesa-shaped compound semiconductor multilayer part 20. . This side surface 40 becomes the main incident surface.
The infrared shielding part 30 will not be restrict | limited especially if comprised with the material with low infrared transmittance. Specifically, the transmittance of infrared light having a wavelength at which the sensitivity of the infrared sensor device is highest is preferably 50% or less, and more preferably 30% or less.
Specific materials include materials such as Al, Au, Pt, and Ti, laminates thereof, and alloys thereof.
From the viewpoint of manufacturability, it is preferable to use an output terminal or an electrode (including a wiring for electrically connecting each light receiving element) for taking out a signal from the light receiving element as the infrared shielding unit 30.

<Other configurations>
As shown in FIG. 1, the light receiving unit 50 may include a wiring unit, an output terminal, and an electrode unit in addition to the compound semiconductor stacked unit 20. When providing the wiring part for connecting a some light receiving element in series or in parallel, it is preferable to provide the insulating layer 60 on the side surface of the wiring part and the compound semiconductor laminated part 20. Examples of the material of the insulating layer 60 include silicon oxide and silicon nitride, but any material may be used as long as it is an insulating material. Moreover, you may provide a protective layer so that the whole light-receiving part may be covered besides a connection terminal and a pad. In the case of providing the protective layer, it is preferable to use a material having a high infrared transmittance. Examples thereof include silicon oxide, silicon nitride, titanium oxide, and titanium nitride.

<Embodiment of Infrared Sensor Device>
Next, a specific embodiment of an infrared sensor device using the light receiving unit 50 described in FIG. 1 will be described with reference to the drawings. The specific configuration of the light receiving portions 50a and 50b is as described with reference to FIG. 1, and the detailed description of the light receiving portions 50a and 50b (for example, the detailed structure of the compound semiconductor stacked portion 20, the insulating layer 60, the second layer). The mesa unit 202 and the like are omitted.

<First Embodiment>
FIG. 2 is a schematic diagram of the infrared sensor device according to the first embodiment of the present invention.
2A is a schematic plan view, and FIG. 2B is a cross-sectional view taken along the line AA ′ of FIG. In FIG. 2A, only the edge portions of the infrared shielding portions 30a and 30b and the output terminals 31a and 31b are indicated by dotted lines.
The infrared sensor device according to the first embodiment includes two light receiving portions 50a and 50b formed on the same substrate 10.

  The light receiving unit 50a includes, for example, a light receiving element including a mesa-shaped compound semiconductor stacked unit 20a having a PN junction or a PIN junction, an infrared shielding unit 30a covering a part of the compound semiconductor stacked unit 20a, and an output terminal 31a. And having. Similarly, the light receiving unit 50b includes a light receiving element including a mesa-shaped compound semiconductor stacked unit 20b having a PN junction or a PIN junction, an infrared shielding unit 30b covering a part of the compound semiconductor stacked unit 20b, and an output terminal 31b. And having. Then, as shown in FIG. 2, these parts are arranged on the substrate 10 in a straight line in the order of the output terminal 31a, the compound semiconductor stacked unit 20a, the compound semiconductor stacked unit 20b, and the output terminal 31b.

The compound semiconductor stacked portions 20a and 20b of the light receiving portions 50a and 50b are formed in substantially the same mesa shape, and the four side surfaces forming the mesa shape are parallel to the corresponding side surfaces in the compound semiconductor stacked portions 20a and 20b. Formed to be.
The infrared shielding part 30a covers a part of the compound semiconductor multilayer part 20a of the light receiving part 50a, and forms a side surface not covered with the infrared shielding part 30a on the side surface of the compound semiconductor multilayer part 20a. In the case of FIG. 2, the infrared shielding portion 30a covers the entire upper surface of the mesa-shaped compound semiconductor stacked portion 20a and the three side surfaces including the entire surface of the compound semiconductor stacked portion 20a on the compound semiconductor stacked portion 20b side. Placed in.

Thereby, the infrared shielding part 30a does not cover the right side surface 40a in FIG. 2 which is the side surface opposite to the compound semiconductor stacked portion 20b among the four side surfaces of the compound semiconductor stacked portion 20a, The two side surfaces are arranged so as to cover the entire side surface on the compound semiconductor stacked portion 20b side of the two side surfaces, and to cover only the portion opposite to the side surface 40a of the two side surfaces adjacent to the left and right sides of the side surface 40a. Of the four side surfaces of the compound semiconductor stacked unit 20a included in the light receiving element in the light receiving unit 50a, the surface having the largest ratio of the region not covered by the infrared shielding unit 30a is the side surface 40a. Becomes the main incident surface.

  Similarly, the infrared shielding unit 30b covers a part of the compound semiconductor stacked unit 20b of the light receiving unit 50b, and forms a side surface that is not covered with the infrared shielding unit 30b on the side surface of the compound semiconductor stacked unit 20b. In the case of FIG. 2, the infrared shielding portion 30b covers the entire upper surface of the mesa-shaped compound semiconductor stacked portion 20b and the three side surfaces including the entire surface of the compound semiconductor stacked portion 20b on the compound semiconductor stacked portion 20a side. Placed in.

  Thereby, the infrared shielding portion 30b does not cover the left side surface 40b in FIG. 2 which is the side surface opposite to the compound semiconductor stacked portion 20a among the four side surfaces, and the side surface 40b among the entire upper surface and the four side surfaces. The entire side surfaces facing each other are covered, and only the portion opposite to the side surface 40b of the two side surfaces adjacent to the left and right of the side surface 40b is covered. Of the four side surfaces of the compound semiconductor stacked unit 20b included in the light receiving element in the light receiving unit 50b, the surface where the ratio of the region not covered by the infrared shielding unit 30b is maximized is the side surface 40b. Becomes the main incident surface.

  That is, as shown in FIG. 2A, the main incident surface that is not covered by the infrared shielding portion 30a of the compound semiconductor stacked portion 20a of the light receiving element of one of the light receiving portions 50a as shown in FIG. The four side surfaces of the compound semiconductor stacked portions 20a and 20b formed in a mesa shape so that the side surface 40a of the other light receiving portion 50b and the side surface 40b as the main incident surface of the light receiving element of the other light receiving portion 50b are not parallel to each other. The side surfaces 40a and 40b to be the incident surfaces are selected.

  By making the side surfaces 40a and 40b that are not parallel to each other in the mesa-shaped compound semiconductor stacked portions 20a and 20b as the main incident surfaces, as shown in FIG. 2, the field of view FOVa of one light receiving portion 50a and the other light receiving portion 50b Is different from the field of view FOVb. That is, when the side surfaces which are parallel to each other in the compound semiconductor stacked portions 20a and 20b are the main incident surfaces, the fields of the light receiving portions 50a and 50b are in the same direction. In order to make the visual fields of the light receiving portions 50a and 50b be in different directions, the side surfaces that are not parallel to each other, for example, the side surfaces 40a and 40b, in the compound semiconductor stacked portions 20a and 20b are the main incident surfaces.

By forming the infrared shielding portions 30a and 30b from a metal material, the object to be detected is displayed on each field of view based on the outputs from the infrared shielding portion 30a and the output terminal 31a and the outputs from the infrared shielding portion 30b and the output terminal 31b. It is possible to detect whether or not the object exists in the inside or the operation of the detection object.
For example, when this infrared sensor device is used as a user presence detection device, the field of view FOVa of one light receiving unit 50a is set to an area where the human body is unlikely to exist (for example, the ceiling), and the other light receiving unit When the visual field FOVb of 50b is set in an area where there is a high possibility that a human body exists (for example, the front of the monitor), if the difference between the outputs of both the light receiving units 50a and 50b is smaller than the threshold, it can be detected that the user is away from the seat. If the difference between the outputs of the light receiving parts 50a and 50b is larger than the threshold value, it can be detected that the user is present. For example, as shown in FIG. 2, the outputs of the output terminals 31a and 31b of the light receiving units 50a and 50b are input to the arithmetic circuit 80, and the arithmetic circuit 80 calculates the output difference between the light receiving unit 50a and the light receiving unit 50b. By comparing this difference with a preset difference threshold, it is determined whether the user is in the seat, and the result is displayed on a display device, for example, so that the presence detection result is notified. do it.

Second Embodiment
FIG. 3 is a schematic view of an infrared sensor device according to the second embodiment of the present invention.
3A is a schematic plan view, and FIG. 3B is a cross-sectional view taken along the line AA ′ of FIG. In FIG. 3A, the infrared shielding part 30 and the electrodes 31a and 31b as output terminals are indicated by dotted lines only at the edge part.
Compared with the infrared sensor device according to the first embodiment, the infrared sensor device according to the second embodiment includes a part of the compound semiconductor stacked portions 20a and 20b of both the light receiving portions 50a and 50b by the integral infrared shielding portion 30. Is different in that the infrared shielding part 30 is shared.

  As shown in FIG. 3, the infrared shielding part 30 is arranged from the upper surface of the compound semiconductor multilayer part 20a of the light receiving part 50a to the upper surface of the compound semiconductor multilayer part 20 part of the light receiving part 50b. As a result, the infrared shielding portion 30 does not cover the right side surface 40a of the light receiving portion 50a in FIG. 3, and the side surface 40a of the entire upper surface, the entire side surface facing the side surface 40a, and the two side surfaces adjacent to the left and right of the side surface 40a. 3 is covered, and the left side surface 40b of the light receiving portion 50b in FIG. 3 is not covered, and the entire upper surface, the entire side surface facing the side surface 40b, and the two side surfaces 40b adjacent to the left and right of the side surface 40b. Only the opposite side portion is covered, and further, the space between the light receiving portion 50a and the light receiving portion 50b is covered.

That is, also in the second embodiment, of the four side surfaces of the mesa-shaped compound semiconductor multilayer portions 20a and 20b of the light receiving portions 50a and 50b, the side surfaces 40a and 40b that are not parallel to each other are the main incident surfaces.
Next, the operation of the infrared sensor device of the second embodiment will be described with reference to FIG. FIG. 4A is an equivalent circuit diagram when each of the light receiving portions 50a and 50b in which the two light receiving elements, that is, the compound semiconductor stacked portions 20a and 20b are connected in series in FIG. b) is an equivalent circuit diagram showing the diode as a circuit.

In each of the light receiving parts 50a and 50b, when the light to be detected enters the light absorption layer of the compound semiconductor stacked parts 20a and 20b, an electron-hole pair is generated, and when no external bias is applied, Diffusion to the n-layer side and holes diffuse to the p-layer side, and photovoltaics IpA and IpB are generated between the n-layer and the p-layer.
A signal generated between the output terminals 31a and 31b in FIG. 4B will be described.

Since the light receiving portions 50a and 50b have R _0A and R _0B as internal resistances, the current Ip flowing between the output terminals 31a and 31b is expressed by the following equation (1).
Ip = (IpA × R _0A −IpB × R _0B ) / (R _0A + R _0B ) (1)
If the internal resistances R _0A and R _0B are the same, Ip is expressed by the following equation (2).
Ip = (1/2) × (IpA−IpB) (2)
That is, it can be seen that a signal difference between the light receiving portions 50a and 50b can be output by a signal between the output terminals 31a and 31b. That is, in the case of the second embodiment, it is not necessary to calculate the difference between the signals generated in the light receiving units 50a and 50b, so that the processing load on the calculation circuit 80 can be reduced accordingly.

As described above, the light receiving device of the first and second embodiments, that is, the infrared sensor device, has a high S without passing through other means such as an amplifier and an arithmetic element and without being affected by external noise. / N ratio, which is suitable for detecting the position and movement of a weak radiation light source.
Further, by further including an arithmetic circuit 80 to which the output terminals 31a and 31b are connected, the difference between the signals generated in the first and second light receiving portions 50a and 50b, and the comparison result between the difference and the threshold value can be easily obtained. It becomes possible to obtain. Although a specific mode of the arithmetic circuit 80 is not particularly limited, for example, an arithmetic circuit 80 using an operational amplifier and a resistor can be used. A specific example of this operational amplifier is a transimpedance amplifier. The transimpedance amplifier converts the output current of the output terminal into a voltage signal. When such an operational amplifier is connected to the output terminals 31a and 31b of the two light receiving sections 50a and 50b, the output terminals 31a and 31b are short-circuited by a low impedance (Virtual Short), and a differential short-circuit current is output (formula (2) )). Further, a voltage signal proportional to the differential current is obtained at the output of the operational amplifier.

  Although the current obtained from the output terminal is shown here, the open-circuit voltage can be extracted by using a high input impedance amplifier. Accordingly, a difference in open circuit voltage between the light receiving unit 50a and the light receiving unit 50b is obtained. The open-circuit voltage may be output depending on the application, but in many cases, particularly in the case of a light receiving part formed of a narrow gap semiconductor (InSb, InAsSb, etc.), it is difficult to be affected by the temperature characteristics of the internal resistance of the light receiving part. For this purpose, it is preferable to output a short-circuit current as described above.

<Third Embodiment>
FIG. 5 is a schematic diagram of an infrared sensor device according to a third embodiment of the present invention.
FIG. 5A is a schematic plan view, and FIG. 5B is a cross-sectional view taken along line AA ′ of FIG. In FIG. 5A, only the edge portions of the infrared shielding portions 30a and 30b and the electrodes 31a and 31b as output terminals are indicated by dotted lines.
The infrared sensor device of the third embodiment is different from that of the first embodiment in that the light receiving units 50a and 50b each have a plurality of light receiving elements connected in series. In FIG. 5, three light receiving elements are connected in series with each of the light receiving portions 50a and 50b.

In addition, the side surface 40a not covered with the infrared shielding part 30a of the compound semiconductor laminated part 20a of the light receiving element of the light receiving part 50a is parallel between all the light receiving elements connected in series, and is a compound of the light receiving element of the light receiving part 50b. The side surface 40b of the semiconductor laminated portion 20b that is not covered with the infrared shielding portion 30b is also parallel between all the light receiving elements connected in series.
A plurality of light receiving elements connected in series is preferable in that the infrared sensor device is more sensitive than the infrared sensor device of the first embodiment.

In the infrared sensor device of the third embodiment shown in FIG. 5, in each of the light receiving portions 50a and 50b, the side surface 40a that is not covered with the infrared shielding portions 30a and 30b of the compound semiconductor stacked portions 20a and 20b as the light receiving elements. 40b is parallel to each other. In other words, in each light receiving element, the side surface in which the ratio of the region not covered by the infrared shielding portion of the compound semiconductor laminated portion is the maximum, that is, 40a and 40b are parallel to all the light receiving elements connected in series. The side surfaces 40a and 40b of any one of the light receiving elements are main incident surfaces.
In the case of FIG. 5, since 40a which is the main side surface in the light receiving unit 50a and 40b which is the main side surface in the light receiving unit 50b are not parallel, the two side surfaces 40a and 40b are used as the main side surfaces. An infrared sensor device including the units 50a and 50b can be realized.

In FIG. 5, for example, any one of the light receiving elements in which the side surfaces 40 a in which the ratio of the region not covered by the infrared shielding part of the compound semiconductor stacked part of each light receiving element of the light receiving part 50 a is maximized are connected in series. When the elements are non-parallel, the light source center position and the light receiving unit 50a when the output of the light receiving unit 50a becomes maximum when the light source having the same intensity is moved on a spherical surface equidistant from the center of the light receiving unit 50a. A plane perpendicular to a straight line connecting the centers of the two is defined as a main incident surface. In addition, in the respective light receiving elements of the light receiving portions 50a and 50b, the infrared shielding portions 30a and 30b are set so that the main incident surface of the light receiving portion 50a set in this way and the main incident surface of the light receiving portion 50b are not parallel. What is necessary is just to determine the surface of the compound semiconductor lamination | stacking part 20a, 20b covered by.
As shown in FIG. 5, even when a light receiving unit having a plurality of light receiving elements is used, a difference between outputs of the output terminals 31 a and 31 b is calculated by the arithmetic circuit 80 and compared with a threshold value. It is possible to easily detect whether or not an object exists in each field of view or the operation of the detection object.

<Fourth embodiment>
FIG. 6 is a schematic diagram of an infrared sensor device according to a fourth embodiment of the present invention.
As shown in FIG. 6, the infrared sensor device 100 according to the second embodiment is arranged in a package case 500 in which an optical window 501 is installed, and two output terminals (not shown) of the infrared sensor device 100 and a package case. A wiring (not shown) in 500 is connected by a wire 502. The output signal of the infrared sensor device 100 may be taken out via the wiring in the package case 500 and calculated by the arithmetic circuit 80 in the same manner as the infrared sensor in the second embodiment. Alternatively, a signal processing unit is installed in the package case 500, an output signal from the wiring in the package case 500 is input to the signal processing unit, and a desired output signal obtained by arithmetic processing in the signal processing unit is externally provided. You may make it take out.
In the infrared sensor device of the fourth embodiment, if the package case 500 is formed of a member that substantially shields infrared rays, the second main surface side of the substrate of the infrared sensor device 100, that is, the compound semiconductor stacked portion is not formed. There is no need to further include an infrared shielding part on the side, and an infrared sensor device having a plurality of desired different fields of view can be realized.

<Effect of embodiment>
As described above, in this embodiment, since the side surfaces that are not parallel to each other among the side surfaces of the mesa-shaped compound semiconductor stacked portion of each of the two light receiving portions are the main incident surfaces that are not covered with the infrared shielding portion, The field of view determined according to the orientation of the surface is different between the two light receiving units. Therefore, an infrared sensor device having two light receiving portions with different fields of view can be realized without providing external parts and the like, and the infrared sensor device can be downsized.

Hereinafter, an example of the light receiving unit 50 used in the infrared sensor device of the present embodiment will be described.
A 1 μm thick n-type InSb layer, a 2 μm thick π-type InSb layer, a 0.02 μm thick AlInSb barrier layer, and a 0.5 μm thick p-type InSb layer are stacked in this order on a GaAs substrate. Then, a PIN junction photodiode structure was formed.
Thereafter, two-stage wet etching was performed using a photoresist mask to form a light receiving element having a first mesa portion 201 and a second mesa portion 202 as shown in FIG. The height of the first mesa unit 201 was 2.82 μm, and the height of the second mesa unit 202 was 0.7 μm. The bottom surface of the first mesa unit 201, that is, the surface in contact with the second mesa unit 202, has a square shape of 90 μm × 90 μm. The angle formed by the slope of the first mesa 201 and the surface of the substrate 10 was 45 degrees.

After forming the first and second mesas 201 and 202, an insulating layer 60 made of silicon nitride is formed, and the top (p contact part) 201a of the first mesa 201 and the top of the second mesa 202 ( A part of silicon nitride of the (n contact portion) 202a was removed to form a contact hole.
Next, an infrared shielding part 30 having a laminated wiring structure of Au / Pt / Ti is formed by a lift-off method using a photoresist mask, and the first mesa part 201 excluding one side surface of the first mesa part 201 and The infrared shielding part 30 was formed in a part including the second mesa part 202 and the substrate 10. Thereby, the side surface 40 not covered with the infrared shielding unit 30 was formed on a part of the side surface of the first mesa unit 201, and the light receiving unit 50 was manufactured.

Using this light receiving unit 50, an output signal with respect to a black body furnace radiation at a temperature of 500K was measured.
As a measuring method, the light receiving unit 50 is placed at a distance of 10 cm from the exit of the blackbody furnace (diameter φ22 mm), and the output of the light receiving unit 50 is changed while changing the incident angle with respect to the horizontal plane to the side surface 40 of the light receiving unit 50. The signal was measured. In order to eliminate the influence of disturbance, modulation by chopping of blackbody furnace radiation and demodulation using a lock-in amplifier were used.

FIG. 7 shows the measurement results. The horizontal axis represents the incident angle, and the vertical axis represents the output signal of the light receiving unit 50.
As a result, in FIG. 1, assuming that the horizontal plane passing through the center M of the light receiving unit 50 is zero degrees and the angle increases clockwise, the incident angle to the light receiving unit 50 is 135 degrees as shown by the broken line in FIG. It can be seen that the highest output is obtained in the vicinity of (45 degrees with respect to the substrate vertical). When the incident angle to the light receiving unit 50 is 0 to 45 degrees, that is, when infrared rays are incident on the side surface facing the side surface 40 which is the main incident surface of the compound semiconductor stacked unit 20 in FIG. In this case, the infrared ray output from the blackbody furnace is not directly incident on the light absorption layer 22, but the output of the light receiving unit 50 was confirmed to be about half that of the incident angle of 135 degrees. This is because infrared rays are incident on the substrate 10 from a region not covered by the infrared shielding portion 30 of the second mesa portion 202, reflected by the second main surface 10 b of the substrate 10, and indirectly to the light absorption layer 22. This is thought to be due to the incidence of infrared rays. In any case, from this example, according to the infrared sensor device of the present embodiment, the compound semiconductor stack of the light receiving element of the light receiving unit is provided with a side surface as a main incident surface that is not covered with the infrared shielding unit. A plurality of light receiving portions 50 are provided on the same substrate 10 and the light receiving portions 50 are formed so that the main incident surfaces are not parallel between the light receiving portions 50, and target infrared rays are incident from any of the main incident surfaces. Thus, it was confirmed that an infrared sensor device capable of separating and selecting light from different fields of view can be realized without using external components such as a lens, a complicated optical system, and a field-of-view restriction unit.

<Others>
In addition, in the said embodiment, although the case where the compound semiconductor laminated part 20 was formed in the mesa shape was demonstrated, it is not restricted to this, A polyhedral shape may be sufficient.
Further, the area of the surface may not be the same in the compound semiconductor stacked unit 20. Similarly, in the case of a light receiving unit including a plurality of light receiving elements, the area of each surface of the compound semiconductor stacked unit 20 may be different between the plurality of light receiving elements.

In the above embodiment, the case where one of the four side surfaces of the mesa-shaped compound semiconductor stacked unit 20 is not covered with the infrared shielding unit 30 has been described. It may not be covered with the shielding part 30, and the area | region which is not covered with the infrared shielding part 30 of the grade which can exhibit the output characteristic according to the incident infrared rays should just remain.
In the above-described embodiment, the case where each of the plurality of light receiving units has only one light receiving element or a plurality of light receiving elements has been described, but the present invention is not limited to this. The number of light receiving elements constituting each light receiving unit may be different, and one light receiving unit has a plurality of light receiving elements whose main incident surfaces are parallel, and the other light receiving unit has a non-parallel main incident surface. A configuration having a plurality of light receiving elements may also be used.

Moreover, you may provide the output terminal connected to the common connection point of each light-receiving part.
In the above embodiment, the case where the infrared sensor device includes two light receiving units has been described. However, the present invention is not limited to this, and the present invention can also be applied to a case where three or more light receiving units are provided. By providing two or more light receiving portions, infrared rays from three or more different directions can be separated and detected.

  In addition, the scope of the present invention is not limited to the exemplary embodiments and examples shown and described. Based on the knowledge of those skilled in the art, design changes or the like may be added to each embodiment or example, and each embodiment or example may be arbitrarily combined, and is equivalent to the purpose of the present invention. Also includes all embodiments that provide an effect. Further, the scope of the invention can be defined by any desired combination of particular features among all the disclosed features.

  The present invention is suitable as an infrared sensor device including a plurality of light receiving units, which is applied to a human sensor or the like.

DESCRIPTION OF SYMBOLS 10 Board | substrate 20, 20a, 20b Compound semiconductor laminated part 21 N-type compound semiconductor layer 22 Light absorption layer (i-type compound semiconductor layer)
23 p-type compound semiconductor layer 24 barrier layer 201 first mesa part 202 second mesa part 30, 30a, 30b infrared shielding part 31a, 31b output terminal 40, 40a, 40b side face not covered with infrared shielding part 50, 50a, 50b Light receiving portion 60 Insulating layer 100 Infrared sensor device 500 Package case 501 Optical window 502 Wire

Claims (6)

A plurality of light receiving parts on the same substrate, each including a light receiving element having a polyhedral compound semiconductor laminated part including a photodiode structure and an infrared shielding part covering a part of the compound semiconductor laminated part;
An infrared sensor device in which a main incident surface of the light receiving unit is non-parallel between the plurality of light receiving units. The plurality of light receiving units include a first light receiving unit including only one light receiving element,
The one plane in which the area not covered by the infrared shielding portion is the largest among the planes of the compound semiconductor stacked unit included in the light receiving element of the first light receiving unit is the main incident surface. The infrared sensor device according to 1. The plurality of light receiving units includes a second light receiving unit having the plurality of light receiving elements connected in series,
In the second light receiving portion, one of the flat surfaces of the compound semiconductor stacked portion included in one light receiving element has a maximum area not covered by the infrared shielding portion between all the light receiving elements. In parallel,
The infrared sensor device according to claim 1, wherein the one plane of any one of the plurality of light receiving elements is the main incident surface. The plurality of light receiving units includes a third light receiving unit having the plurality of light receiving elements connected in series,
In the third light receiving portion, one of the planes of the compound semiconductor stacked portion included in one of the light receiving elements is one of the light receiving elements where the area that is not covered by the infrared shielding portion is maximum. Non-parallel between,
Perpendicular to a straight line connecting the center position of the light source and the center of the light receiving unit when the output of the light receiving unit becomes maximum when a light source having a constant intensity is moved on a spherical surface equidistant from the center of the light receiving unit The infrared sensor device according to any one of claims 1 to 3, wherein a flat surface is the main incident surface.   The infrared sensor device according to claim 1, wherein the photodiode structure includes a PN junction or a PIN junction.   The infrared sensor device according to any one of claims 1 to 5, wherein the compound semiconductor stacked portion has a mesa shape having four side surfaces.

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