JP2020129674A - Photodetector - Google Patents

Abstract

To provide a photodetector capable of improving sensitivity to light in a near infrared region with a simple structure.SOLUTION: A photodetector 10 includes: a light detection area 140, having a first surface 15A on which at least part of light in the near infrared region is incident and a second surface 15B opposite to the first surface 15A, for detecting light; a reflection layer 20, provided on the second surface 15B side of the light detection area, for reflecting light. and a quenching resistor 32 connected in series to the light detection area 140 without via bump bonding. The reflection layer 20 is provided between the light detection area 140 and the quenching resistor 32.SELECTED DRAWING: Figure 1

Description

Embodiments of the present invention relate to photodetectors.

A photodetector including a photodetection element that detects light is known. Techniques for increasing the sensitivity of the photodetector to light in the near-infrared region include techniques for increasing the thickness of the depletion layer and techniques for forming irregular asperity in at least the region of the silicon substrate facing the pn junction. Has been done.

JP, 2013-93609, A

However, if the thickness of the depletion layer is increased, it is necessary to increase the driving voltage. Moreover, if the thickness of the depletion layer is increased, it becomes difficult to form a fine array of photodetecting elements. In addition, a dedicated processing device is required to form the irregular asperity on the silicon substrate. That is, conventionally, it has been difficult to improve the sensitivity to light in the near infrared region with a simple configuration.

The present invention has been made in view of the above, and an object of the present invention is to provide a photodetector capable of improving sensitivity to light in the near infrared region with a simple configuration.

The photodetector of the embodiment has a first surface on which at least a part of light in the near-infrared region is incident and a second surface opposite to the first surface, and a photodetection region for detecting light, The reflection layer provided on the second surface side of the detection area and containing a metal that reflects light, and the position in the orthogonal direction orthogonal to the facing direction of the first surface and the second surface overlap with the light detection area. A quenching resistor connected in series to the light detection region without bump bonding. The reflective layer is provided between the light detection region and the quenching resistor.

The figure which shows an example of a photodetector. The figure which shows an example of a photodetector. The figure which shows an example of a photodetector. The figure which shows an example of a photodetector. The figure which shows an example of a photodetector. FIG. 4 is a diagram showing the relationship between the amount of light absorbed and the thickness of the depletion layer. The schematic diagram of a photodetector. The schematic diagram which shows an example of a photodetector. The schematic diagram which shows an example of a photodetector. Explanatory drawing of arrangement|positioning of a penetration electrode. Explanatory drawing which shows an example of the manufacturing method of a photodetector. Explanatory drawing which shows an example of the manufacturing method of a photodetector. Explanatory drawing which shows an example of the manufacturing method of a photodetector. Explanatory drawing which shows an example of the manufacturing method of a photodetector. Explanatory drawing which shows an example of the manufacturing method of a photodetector. Explanatory drawing which shows an example of the manufacturing method of a photodetector. Explanatory drawing which shows an example of the manufacturing method of a photodetector. Explanatory drawing which shows an example of the manufacturing method of a photodetector. Explanatory drawing which shows an example of the manufacturing method of a photodetector. Explanatory drawing which shows an example of the manufacturing method of a photodetector. Explanatory drawing which shows an example of the manufacturing method of a photodetector. Explanatory drawing which shows an example of the manufacturing method of a photodetector. Explanatory drawing which shows an example of the manufacturing method of a photodetector. Explanatory drawing which shows an example of the manufacturing method of a photodetector. Explanatory drawing which shows an example of the manufacturing method of a photodetector. Explanatory drawing which shows an example of the manufacturing method of a photodetector.

The details of the present embodiment will be described below with reference to the accompanying drawings.

(First embodiment)
FIG. 1 is a diagram showing an example of the photodetector 10A.

The photodetector 10A includes a first photodetection layer 12A and a reflective layer 20.

The first light detection layer 12A includes a plurality of first light detection regions 140. The first light detection area 140 detects incident light. The first light detection region 140 is a region that includes a pn junction formed by joining a p-type semiconductor layer containing Si as a main component and an n-type semiconductor layer containing Si as a main component, and functions as a photodiode.

In the present embodiment, as an example, the first photodetection region 140 is formed as a pn-type diode by alternately stacking the p − -type semiconductor layers 14A and the p + -type semiconductor layers 14B on the n-type semiconductor substrate 14C. A case of a configured avalanche photo diode (APD) will be described. The first light detection region 140 is driven in, for example, Geiger mode. Note that the first light detection region 140 may be any region as long as it has a function of detecting light, and is not limited to the APD.

In the first photodetection region 140, a pn junction is formed by an n-type region (n-type semiconductor substrate 14C) and a p-type region (p-type semiconductor layer 14A in FIG. 1) adjacent to the n-type region. Has been done. The first photodetection region 140 is formed by a known technique such as ion implantation, diffusion, or the like. The n-type semiconductor substrate 14C (n-type semiconductor layer) and the -p type semiconductor layer 14A are layers containing silicon as a main component. For example, the n-type semiconductor substrate 14C (n-type semiconductor layer) and the −p-type semiconductor layer 14A are manufactured by epitaxial growth of silicon, doping of a silicon substrate with impurities, or the like.

The first light detection region 140 has a first surface 15A on which light is incident and a second surface 15B opposite to the first surface 15A. The first surface 15A is one of the both end surfaces in the thickness direction of the first light detection region 140. The first surface 15A is a surface on the light incident side in the first light detection region 140. The second surface 15B is the other surface of both end surfaces in the thickness direction of the first light detection region 140. The second surface 15B is a surface on the light emitting side of the first photodetecting layer 12A. Note that the thickness direction of the first light detection region 140 and the facing direction of the first surface 15A and the second surface 15B (see the arrow X direction in FIG. 1) match.

In the present embodiment, in the photodetector 10A, the surface of the pn junction on the n-type semiconductor substrate 14C side in the first photodetection region 140 is the first surface 15A. The surface of the first photodetection region 140 on the p-type semiconductor layer (p− type semiconductor layer 14A, p+ type semiconductor layer 14B) side of the pn junction is defined as a second surface 15B.

The surface of the first photodetection region 140 on the p-type semiconductor layer (p− type semiconductor layer 14A, p+ type semiconductor layer 14B) side of the pn junction may be the first surface 15A.

The first photodetection layer 12A has a configuration in which a plurality of first photodetection regions 140 are arranged, for example, in a matrix along an intersecting surface intersecting in the facing direction. The first photodetection layer 12A has, for example, a configuration in which pixel regions each having a plurality of first photodetection regions 140 as one pixel are arranged in a matrix.

The element isolation portion 29 is provided in the region between the first photodetection region 140 and the first photodetection region 140 in the first photodetection layer 12A. The element isolation portion 29 suppresses the adjacent first photodetection regions 140 from electrically interfering with each other.

The insulating layer 30 and the support substrate 38 are laminated in this order on the first photodetection layer 12A. The insulating layer 30 is a layer made of an insulating material. The support substrate 38 is a substrate that supports the first photodetection layer 12A. The support substrate 38 is made of, for example, silicon, glass, sapphire, or the like.

The insulating layer 30 is provided with the reflective layer 20, the quenching resistor 32, the contact layer 34, and the wiring layer 36 in this order from the first photodetection layer 12A side.

The reflective layer 20 is provided on the second surface 15B side of the first light detection region 140. The reflective layer 20 reflects at least a part of light in the near infrared region. The light of at least a part of the near-infrared region means the light of at least a part of the wavelength in the near-infrared region.

The light in the near infrared region refers to light in the wavelength region of 780 nm or more and 2500 nm or less. The reflective layer 20 preferably reflects at least light in the wavelength region of 780 nm or more and 1100 nm or less.

The reflective layer 20 includes at least a part of the light in the near-infrared region included in the light incident from the first surface 15A of the first photodetection layer 12A (see incident light L1 in FIG. 1) at least as a first light. The thickness, the constituent material, and the like are adjusted in advance so as to realize the reflection that reaches the depletion layer of the light detection region 140.

For example, the thickness of the reflective layer 20 is the relative position of the configuration of the first photodetection region 140, the constituent material of the reflective layer 20, and the first photodetection layer 12A in the facing direction (the arrow X direction) of the reflective layer 20. , Etc. may be appropriately adjusted so as to satisfy the above reflection condition.

The reflective layer 20 is made of a material capable of reflecting at least part of light in the near infrared region. Specifically, the reflective layer 20 is made of a metal such as Al, Ti, TiN, W, or Mo which is generally used in a semiconductor process and its alloy material.

The region between the first photodetection region 140 and the reflective layer 20 in the facing direction of the photodetector 10A is preferably made of a material that transmits at least part of light in the near infrared region.

The reflective layer 20 may be provided so as to cover at least a part of the second surface 15B of the first photodetection region 140 along the orthogonal direction orthogonal to the facing direction. Further, the reflective layer 20 covers the entire area of the first light detection area 140 on the second surface 15B side in the orthogonal direction (direction orthogonal to the arrow X direction in FIG. 1) orthogonal to the facing direction. It may be provided in such a manner. Further, as shown in FIG. 1, the reflective layer 20 covers the second surface 15B side of the plurality of first photodetection regions 140 in the first photodetection layer 12A continuously along the orthogonal direction. May be provided.

The position of the reflective layer 20 in the facing direction (the arrow X direction) of the photodetector 10A may be on the side of the second surface 15B of the first photodetection region 140, but the position of the reflection layer 20 and the first photodetection layer 12A is the same. It is preferable to be provided between the shunt resistor 32.

The quenching resistor 32 is connected in series to the first light detection region 140. Polysilicon, for example, is used for the quenching resistor 32.

The quenching resistor 32 serves as a path for the electric charge amplified in the pn junction of each first photodetection region 140. That is, the quenching resistor 32 limits the amount of current flowing through the first light detection region 140. For example, when one photon is incident and the first photodetection region 140 is Geiger discharged, the voltage drop due to the quenching resistor 32 terminates the amplification action. Therefore, a pulsed output signal is obtained from the first photodetection region 140.

A wiring layer 36 and a through electrode 40 are connected to the quenching resistor 32 via a contact layer 34. The wiring layer 36 functions as an anode electrode.

In the example shown in FIG. 1, the reflective layer 20 includes a quenching resistor 32, a contact layer 34, a wiring layer 36, a first photodetection region 140, and a first photodetection region 140 in the facing direction (see the arrow X direction in FIG. 1). It is provided between. The reflective layer 20 may be provided between at least one of the wiring layer 36, the contact layer 34, the quenching resistor 32, and the first photodetection layer 12A.

By providing the reflection layer 20 between the first photodetection layer 12A and the quenching resistor 32 in the facing direction, the quenching resistor 32, the contact layer 34 connected to the quenching resistor 32, and the wiring layer. It is possible to improve the degree of freedom in wiring and layout of the wirings 36 and the like. By increasing the layout flexibility of the quenching resistor, it is possible to reduce the sheet resistance value of the quenching resistor and reduce the variation in the resistance value due to the variation in processing.

Further, by providing the reflection layer 20 between the first photodetection layer 12A, the quenching resistor 32, the contact layer 34, and the wiring layer 36 in the facing direction, the degree of freedom in wiring layout is increased. It can be further improved. Further, since the degree of freedom in wiring layout is improved, it is possible to reduce wiring resistance and parasitic capacitance.

On the other hand, the electrode layer 26 is provided on the surface of the first photodetection layer 12A opposite to the wiring layer 36. In the photodetector 10A, the electrode layer 26 functions as a cathode electrode. The electrode layer 26 is connected to the through electrode 44 via the through electrode 42 and the electrode layer 37.

That is, the first photodetection layer 12A including the first photodetection region 140, the quenching resistor 32, the contact layer 34, the wiring layer 36, and the electrode layer 26 function as SiPM (Silicon Photomultipliers).

In the present embodiment, the electrode layer 26 is provided on the first surface 15A side of the first light detection region 140. Therefore, it is preferable that at least a region of the electrode layer 26 that overlaps the first photodetection region 140 is a transparent electrode that transmits at least a part of light in the sensitivity wavelength region of the first photodetection region 140.

Light that has entered the photodetector 10A configured as described above from the first surface 15A side (see the incident light L1 in FIG. 1) enters the first photodetection region 140. Further, the light incident on the first light detection region 140 is reflected by the reflective layer 20 toward the first light detection region 140 side (see reflected light L2 in FIG. 1).

Between the wiring layer 36 and the electrode layer 26, a pn junction of the first photodetection region 140 is driven by, for example, a reverse bias voltage equal to or higher than the avalanche breakdown voltage, under the control of a signal processing circuit (not shown). Voltage is being applied. In this state, when light is incident on the first photodetection region 140 from the first surface 15A, a pulsed current flows in the first photodetection region 140 in the reverse bias direction. Then, this current is output to a signal processing circuit (not shown) as an electric signal. In this way, the photodetector 10A detects light.

As described above, the photodetector 10A of the present embodiment includes the first photodetection layer 12A and the reflective layer 20. The first light detection layer 12A includes a first light detection region 140. The first light detection region 140 has a first surface 15A on which light is incident and a second surface 15B opposite to the first surface 15A, and includes a p-type semiconductor layer containing Si as a main component and Si. It includes a pn junction in which an n-type semiconductor layer which is contained as a main component is joined. The reflective layer 20 is provided on the first surface 15A side of the first light detection region 140 and reflects at least a part of the light in the near infrared region.

Here, it is known that the smaller the thickness of the depletion layer in the first photodetection region 140, the lower the spectral sensitivity of the photodetector 10 in the near infrared region. For example, the thickness of the depletion layer of the first photo detection region 140 is generally 2 μm to 3 μm when the first photo detection region 140 is an APD using Si as a semiconductor substrate. The reverse bias voltage as a drive voltage is generally 100V or less. The spectral sensitivity in the near infrared region of the first light detection region 140 having such a thickness was less than 10%. Further, for example, in order to absorb 90% of near-infrared light of 850 nm, the thickness of the depletion layer needs to be several tens of μm or more (for example, 30 μm or more).

The larger the thickness of the depletion layer, the higher the drive voltage needed. For example, when the thickness of the depletion layer is several tens of μm or more, the driving voltage needs to be several hundreds V or more. Further, as the thickness of the depletion layer increases, it becomes more difficult to form a fine array.

On the other hand, 10 A of photodetectors of this Embodiment are equipped with the reflective layer 20 which reflects the light of at least one part of a near infrared region on the 2nd surface 15B side of the 1st photodetection area|region 140.

Therefore, in the photodetector 10A according to the present embodiment, the incident light L1 that has passed through the first photodetection region 140 and the reflected light L2 from the reflection layer 20 reaches the first photodetection region 140 again. Becomes

Due to the reflection of light by the reflection layer 20, the optical path length of the light incident on the first light detection region 140 in the first light detection region 140 is made longer than that in the configuration without the reflection layer 20. You can

Therefore, the photodetector 10A of the present embodiment can improve the sensitivity to light in the near infrared region.

In addition, the photodetector 10A according to the present embodiment can adjust the near-infrared region of the photodetector 10A without adjusting the thickness of the first photodetection region 140 (specifically, the depletion layer) or the drive voltage. The sensitivity to light can be improved. Further, the photodetector 10A of the present embodiment can improve the sensitivity to light in the near infrared region without increasing the chip size of the photodetector 10A and while maintaining the response characteristics.

Further, in the photodetector 10A, since the quenching resistor 32 and the contact layer 34 are not disposed on the first surface 15A side of the first photodetection layer 12A, the first photodetection layer 12A has the first photodetection layer 12A. The aperture ratio of the light detection region 140 can be increased as compared with the case where this configuration is not used.

(Second embodiment)
In the present embodiment, a mode in which the reflective layer 20 is arranged at a position different from that of the first embodiment will be described.

FIG. 2 is a diagram showing an example of the photodetector 10B.

The photodetector 10B includes a first photodetection layer 12A and a reflective layer 20.

The first photodetection layer 12A is similar to that of the first embodiment. That is, the first photodetection layer 12A has a plurality of first photodetection regions 140. The first photodetection region 140 has a configuration in which the p− type semiconductor layers 14A and the p+ type semiconductor layers 14B are alternately stacked on the n type semiconductor substrate 14C. Further, in the first light detection region 140, a pn junction is formed by the n-type region (n-type semiconductor substrate 14C) and the p-type region (p-type semiconductor layer 14A) adjacent to the n-type region. There is.

The element isolation portion 29 is provided in the region between the first photodetection region 140 and the first photodetection region 140 in the first photodetection layer 12A. The element isolation part 29 is similar to that of the first embodiment.

The first light detection region 140 has a first surface 15A on which light is incident and a second surface 15B opposite to the first surface 15A. In the present embodiment, the first photo-detecting region 140 has the surface of the pn junction on the n-type semiconductor substrate 14C side as the second surface 15B. In addition, in the present embodiment, the first photodetection region 140 has the surface of the pn junction on the p-type semiconductor layer (p− type semiconductor layer 14A, p+ type semiconductor layer 14B) side as the first surface 15A.

The insulating layer 30, the adhesive layer 24, and the support substrate 39 are laminated in this order on the first photodetection layer 12A.

The insulating layer 30 is provided with a quenching resistor 32, a contact layer 34, and a wiring layer 36 in order from the first light detection layer 12A side. The insulating layer 30 is the same as that of the first embodiment except that the reflective layer 20 is not provided.

Specifically, the insulating layer 30 is provided with a quenching resistor 32 that is connected in series to the first light detection region 140. Further, the insulating layer 30 is provided with a wiring layer 36 connected to the quenching resistor 32 via the quenching resistor 32 and the contact layer 34. The wiring layer 36 is connected to the electrode layer 26 via the through electrode 40. In the present embodiment, the wiring layer 36 and the electrode layer 26 function as an anode electrode.

The support substrate 39 is made of a material that transmits at least part of light in the sensitivity wavelength region of the first light detection region 140. The adhesive layer 24 adheres the support substrate 39 and the insulating layer 30. The adhesive layer 24 is also made of a material that transmits at least part of light in the sensitivity wavelength region of the first light detection region 140.

Further, in the insulating layer 30, the wiring layer 36, the contact layer 34, and the quenching resistor 32, at least a region overlapping each of the first photodetection regions 140 is a sensitivity wavelength region of the first photodetection region 140. It is made of a material that transmits at least part of light.

The reflective layer 20 is provided on the second surface 15B side of the first light detection region 140. As described above, in the present embodiment, the surface of the first photodetection region 140 in the photodetector 10B on the n-type semiconductor substrate 14C side of the pn junction is the second surface 15B. In addition, in the present embodiment, the first photodetection region 140 has the surface of the pn junction on the p-type semiconductor layer (p− type semiconductor layer 14A, p+ type semiconductor layer 14B) side as the first surface 15A. Therefore, in the present embodiment, the reflective layer 20 is provided on the second surface 15B side of the first photodetection region 140 and on the n-type semiconductor substrate 14C side of the pn junction.

That is, in the present embodiment, the position of the reflective layer 20 in the facing direction of the photodetector 10B (see the arrow X direction in FIG. 2) is the second surface 15B side of the first photodetection region 140. , And on the opposite side of the quenching resistor 32 through the first light detection region 140.

The constituent material and thickness of the reflective layer 20 are the same as those in the first embodiment.

In addition, in the present embodiment, the reflective layer 20 has a reflective property of reflecting at least a part of light in the near-infrared region and also has conductivity. Therefore, in this embodiment, the reflective layer 20 functions as a cathode electrode.

Note that an electrode layer may be separately provided on the reflective layer 20, and the electrode layer may be used as a cathode electrode. In this case, the reflective layer 20 may not have conductivity. As described above, when the reflective layer 20 does not function as an electrode or a resistor, no voltage is applied to the reflective layer 20.

When an electrode layer used as a cathode electrode is laminated on the reflective layer 20, the electrode layer is configured to have the following characteristics. Specifically, when the electrode layer (cathode electrode) is provided between the reflective layer 20 and the first light detection region 140, the electrode layer is transparent and transmits at least part of light in the near infrared region. It may be an electrode. On the other hand, when the electrode layer (cathode electrode) is provided on the side of the reflective layer 20 opposite to the first light detection region 140, the electrode layer may be a layer having conductivity and is not limited to the transparent electrode. ..

Light that has entered the photodetector 10B of the present embodiment from the first surface 15A side (see incident light L1 in FIG. 2) enters the first photodetection region 140. Further, the light incident on the first light detection region 140 is reflected by the reflection layer 20 toward the first light detection region 140 side (see reflected light L2 in FIG. 2).

That is, the reflected light L2 from the reflective layer 20 of the incident light L1 that has passed through the first light detection area 140 reaches the first light detection area 140 again. Due to the reflection of light by the reflection layer 20, the optical path length of the light incident on the first light detection region 140 in the first light detection region 140 is made longer than that in the configuration without the reflection layer 20. You can

Between the wiring layer 36 and the reflection layer 20 (cathode electrode), a reverse-biased avalanche breakdown is applied to the pn junction of the first photodetection region 140 by the control of a signal processing circuit (not shown). A drive voltage higher than the applied voltage is applied. In this state, when light is incident from the first surface 15A, a pulsed current flows in the first photodetection region 140 in the reverse bias direction. Then, this current is output to a signal processing circuit (not shown) as an electric signal. In this way, the photodetector 10B detects light.

As described above, the photodetector 10B according to the present embodiment includes the first photodetection layer 12A and the reflective layer 20. The first light detection layer 12A includes a first light detection region 140. In the present embodiment, the first photo-detecting region 140 has the surface of the pn junction on the n-type semiconductor substrate 14C side as the second surface 15B. In addition, in the present embodiment, the first photodetection region 140 has the surface of the pn junction on the p-type semiconductor layer (p− type semiconductor layer 14A, p+ type semiconductor layer 14B) side as the first surface 15A.

The reflective layer 20 is arranged on the second surface 15B side of the first photodetection region 140. That is, the reflective layer 20 is arranged on the opposite side of the quenching resistor 32 with respect to the first light detection region 140.

Thus, even when the reflective layer 20 is arranged on the opposite side of the quenching resistor 32 with respect to the first photodetection region 140, the reflective layer 20 is provided on the second surface 15B side of the first photodetection region 140. By arranging, the photodetector 10B can obtain the same effect as that of the first embodiment.

Further, by disposing the reflection layer 20 on the side opposite to the quenching resistor 32 with respect to the first light detection region 140, the wiring layout of the quenching resistor 32, the contact layer 34, the wiring layer 36, and the like can be improved. The degree of freedom can be improved.

(Third Embodiment)
In the first embodiment, the case where the reflective layer 20 is configured separately from the wiring layer 36 has been described.

In the present embodiment, a case where the reflective layer 20 functions as a part of the wiring layer 36 will be described.

FIG. 3 is a diagram showing an example of the photodetector 10C.

The photodetector 10C includes a first photodetection layer 12A and a reflective layer 20.

The first photodetection layer 12A is similar to that of the first embodiment. That is, the first photodetection layer 12A has a plurality of first photodetection regions 140. The first photodetection region 140 has a configuration in which the p− type semiconductor layers 14A and the p+ type semiconductor layers 14B are alternately stacked on the n type semiconductor substrate 14C. Further, in the first light detection region 140, a pn junction is formed by the n-type region (n-type semiconductor substrate 14C) and the p-type region (p-type semiconductor layer 14A) adjacent to the n-type region. There is.

The element isolation portion 29 is provided in the region between the first photodetection region 140 and the first photodetection region 140 in the first photodetection layer 12A. The element isolation part 29 is similar to that of the first embodiment.

The first light detection region 140 has a first surface 15A on which light is incident and a second surface 15B opposite to the first surface 15A. In the present embodiment, similarly to the first embodiment, in the first photodetection region 140, the surface of the pn junction on the n-type semiconductor substrate 14C side is the first surface 15A. Further, in the present embodiment, the first photodetection region 140 has the second surface 15B on the surface of the pn junction on the p-type semiconductor layer (p− type semiconductor layer 14A, p+ type semiconductor layer 14B) side.

The insulating layer 30 and the supporting substrate 38 are laminated in this order on the first photodetecting layer 12A.

The insulating layer 30 is provided with a quenching resistor 32 that is connected in series with the first light detection region 140. Further, the insulating layer 30 is provided with a wiring layer 36 connected to the quenching resistor 32 via the quenching resistor 32 and the contact layer 34. The wiring layer 36 is connected to the through electrode 40. In the present embodiment, the wiring layer 36 and the through electrode 40 function as an anode electrode.

The support substrate 38 is similar to that of the first embodiment.

The reflective layer 20 is provided on the second surface 15B side of the first light detection region 140. The constituent material and thickness of the reflective layer 20 are the same as those in the first embodiment. In the present embodiment, the reflective layer 20 functions as a part of the wiring layer 36. Therefore, in the present embodiment, the reflective layer 20 further has conductivity.

That is, the constituent material of the overlapping region is adjusted so that the overlapping region of the wiring layer 36, which overlaps with the first light detection region 140, has a reflection characteristic of reflecting at least part of light in the near infrared region. Good. Further, the wiring layer 36 may have a reflection characteristic of reflecting at least a part of light in the near infrared region over the entire region.

The electrode layer 26 is provided on the opposite side of the first photodetection region 140 from the quenching resistor 32. In the present embodiment, the electrode layer 26 is configured as a transparent electrode that transmits at least part of light in the sensitivity wavelength region of the first light detection region 140. The electrode layer 26 is connected to the through electrode 42. In the present embodiment, the electrode layer 26 functions as a cathode electrode.

Light that has entered the photodetector 10C of the present embodiment from the first surface 15A side (see incident light L1 in FIG. 3) enters the first photodetection region 140. Further, the light incident on the first light detection region 140 is reflected by the reflection layer 20 toward the first light detection region 140 side (see reflected light L2 in FIG. 3).

That is, the reflected light L2 from the reflective layer 20 of the incident light L1 that has passed through the first light detection area 140 reaches the first light detection area 140 again. Due to the reflection of light by the reflection layer 20, the optical path length of the light incident on the first light detection region 140 in the first light detection region 140 is made longer than that in the configuration without the reflection layer 20. You can

Between the wiring layer 36 and the reflection layer 20 (anode electrode) and the electrode layer 26 (cathode electrode), a pn junction of the first photodetection region 140 is controlled by a signal processing circuit (not shown). For example, a reverse bias drive voltage equal to or higher than the avalanche breakdown voltage is applied. In this state, when light is incident from the first surface 15A, a pulsed current flows in the first photodetection region 140 in the reverse bias direction. Then, this current is output to a signal processing circuit (not shown) as an electric signal. In this way, the photodetector 10C detects light.

As described above, the photodetector 10C of the present embodiment includes the first photodetection layer 12A and the reflective layer 20. The first light detection layer 12A includes a first light detection region 140. In the present embodiment, the surface of the first photodetection region 140 on the n-type semiconductor substrate (n-type semiconductor substrate 14C) side of the pn junction is the first surface 15A. Further, in the present embodiment, the first photodetection region 140 has the second surface 15B on the surface of the pn junction on the p-type semiconductor layer (p− type semiconductor layer 14A, p+ type semiconductor layer 14B) side.

The reflective layer 20 is arranged on the second surface 15B side of the first photodetection region 140. In the present embodiment, the reflective layer 20 is arranged as a part of the wiring layer 36.

As described above, even when the reflective layer 20 is arranged as a part of the wiring layer 36, by disposing the reflective layer 20 on the second surface 15B side of the first photodetection region 140, the photodetector 10C can be provided. The same effect as that of the first embodiment can be obtained.

(Fourth Embodiment)
In this embodiment mode, a photodetector in which photodetection layers are stacked will be described.

FIG. 4 is a diagram showing an example of the photodetector 11 of the present embodiment. In this embodiment, as an example, a mode in which two photodetection layers are stacked will be described.

The photodetector 11 is a laminated body in which a plurality of photodetection layers are laminated. Specifically, the photodetector 11 includes the first photodetection layer 12A described in the above embodiment, the second photodetection layer 12B including the second photodetection region 142, and the reflective layer 20. , Is provided.

The second photodetection layer 12B has the same configuration as that of the first photodetection layer 12A except that it includes a second photodetection region 142 instead of the first photodetection region 140. Similar to the first photodetection region 140, the second photodetection region 142 includes an n-type semiconductor layer containing Si as a main component and a p-type semiconductor layer adjacent to the n-type semiconductor layer containing Si as a main component. And form a pn junction.

The second light detection area 142 has a first surface 15A on which light is incident and a second surface 15B opposite to the first surface 15A, similarly to the first light detection area 140.

The first photodetection layer 12A and the second photodetection layer 12B are formed on the second surface 15B of the first photodetection region 140 included in the first photodetection layer 12A and the second photodetection layer 12B. The second surface 15B of the included second detection area 142 and the second surface 15B are stacked so as to face the same direction.

The photodetector 11 includes a reflective layer 20. The reflective layer 20 reflects at least part of the light in the near infrared region, as in the first embodiment. The thickness and constituent material of the reflective layer 20 are the same as in the first embodiment.

In the present embodiment, the second photo detection layer 12B is provided between the first photo detection layer 12A and the reflective layer 20.

The photodetector 11 further includes an intermediate layer 50. The intermediate layer 50 is provided between the first photodetection layer 12A and the second photodetection layer 12B. The intermediate layer 50 includes at least a part of light in the sensitivity wavelength region of the first light detection region 140, at least a part of light in the sensitivity wavelength region of the second light detection region 142, and at least one of the near infrared region. It is preferable that it is made of a material that transmits the light of the part. The light of at least a part of the sensitivity wavelength region of the first light detection region 140 means the light of at least a part of the wavelength of the light of the sensitivity wavelength region of the first light detection region 140.

Therefore, the electrode layer 52 included in the intermediate layer 50 is a transparent electrode that transmits at least a part of light in the near infrared region and at least a part of light in the sensitivity wavelength region of the first light detection region 140. Is preferred.

Further, in the photodetector 11, the interlayer between the first photodetection layer 12A and the intermediate layer 50, the interlayer between the intermediate layer 50 and the second detection layer 12B, and the second photodetection layer 12B and the reflection layer 20. It is preferable to provide an antireflection layer 54 between the layers having a refractive index difference of not less than a threshold value among those layers. The antireflection layer 54 reflects at least a part of light in the sensitivity wavelength region of the first photodetection region 140, at least a part of light in the sensitivity wavelength region of the second photodetection region 142, and a reflection in the near infrared region. It is a layer to prevent. This threshold value is such that at least 90% or more of the light incident on each of the first photodetection layer 12A and the second photodetection layer 12B is the first photodetection region 140 of the first photodetection layer 12A, It may be adjusted in advance so that each of the second light detection regions 142 of the second light detection layer 12B can be reached.

Note that when the antireflection layer 54 is provided between the electrode layer 52 included in the intermediate layer 50 and the second photodetection layer 12B, the antireflection layer 54 has the sensitivity wavelength of the first photodetection region 140. It is preferable to have a property of preventing reflection of light in at least part of the region and transmitting at least part of light in the near infrared region. That is, the antireflection layer 54 and the electrode layer 52 are configured as the intermediate layer 50.

The antireflection layer 54 is composed of, for example, a single layer film of a silicon oxide film, a nitride film, or a laminated body of these.

A voltage is applied to the photodetector 11 from the power supply 51. Note that the first surface 15A of the first photodetection region 140 included in the first photodetection layer 12A and the second photodetection region 142 included in the second photodetection layer 12B that configure the photodetector 11 are included. The first surface 15A may be a surface of the pn junction on the n-type semiconductor layer side or a surface of the pn junction on the p-type semiconductor layer (p- type semiconductor layer 14A, p+ type semiconductor layer 14B) side. May be.

Therefore, both the first photodetection layer 12A and the second photodetection layer 12B included in the photodetector 11 have the pn junction with the surface on the n-type semiconductor substrate 14C (n-type semiconductor layer) side facing the first side. It may be the surface 15A. Further, both the first photodetection layer 12A and the second photodetection layer 12B included in the photodetector 11 are p-type semiconductor layers of pn junctions (p- type semiconductor layer 14A, p+ type semiconductor layer 14B). The surface on the side may be the first surface 15A.

Further, the photodetector 11 includes a first photodetection layer 12A (or a second photodetection layer 12B) in which the surface of the pn junction on the n-type semiconductor substrate 14C side is the first surface 15A, and an n-type of pn junction. The second photodetection layer 12B (or the first photodetection layer 12A) having the surface on the semiconductor substrate 14C side as the second surface 15B may be mixed and laminated to form a laminated body.

Also in these cases, the second surface 15B of the first photodetection layer 12A and the second surface 15B of the second photodetection layer 12B face the same direction (see arrow XA in FIG. 4). The laminated structure may be adopted.

Note that the number of stacked photodetection layers (first photodetection layer 12A and second photodetection layer 12B) included in the photodetector 11 is not limited to the two layers shown in FIG. For example, the number of stacked photodetection layers included in the photodetector 11 may be three or five.

In addition, the first photodetection region 140 included in the first photodetection layer 12A and the second photodetection region 142 included in the second photodetection layer 12B are located closer to the reflective layer 20. It is preferable that the thickness of the arranged second light detection region 142 is larger than the thickness of the first light detection region 140.

Further, when the photodetector 11 includes three or more photodetection layers, it is preferable that the photodetection layer disposed closer to the reflection layer 20 has a larger thickness of the photodetection region included therein.

5 and 7 to 9 are schematic views showing an example of a specific configuration of the photodetector 11. In FIGS. 5 and 7 to 9, the photodetectors 10A to 10D described in the above embodiments are collectively referred to as the photodetector 10.

FIG. 5 is a schematic diagram showing an example of the photodetector 11A. Photodetector 11A includes an optical detector 10 _1, which includes a first optical detection layer 12A, a light detector 11 that the optical detector 10 ₂ having a second light detection layer 12B, a stacked.

The photodetector 10 ₁ and the photodetector 10 ₂ are the same as the photodetector 10 described in the above embodiment. The arrangement position of the reflective layer 20 may be different from that of the photodetector 10.

In particular, the optical detector 10 _1, except without the reflective layer 20, the same configuration as the optical detector 10B shown in FIG. Photodetector 10 _2, except without the adhesive layer 24, the same configuration as the optical detector 10B shown in FIG.

In the optical detector 10 _1, the optical detector 10B shown in FIG. 2, instead of the reflecting layer 20 which also functions as a cathode electrode, and an electrode layer 52. The electrode layer 52 includes at least a part of light in the sensitivity wavelength region of the first photodetection region 140, at least a part of light in the sensitivity wavelength region of the second photodetection region 142, and at least one of near-infrared regions. It is a transparent electrode which transmits the light of a part. The electrode layer 52 is connected to the through electrode 42. A photodetector 10 _1, a photodetector 10 _2, between, antireflective layer 54 is provided.

In the photodetector 11A, both the first photodetection layer 12A and the second photodetection layer 12B included in the photodetector 11A have a first photodetection region 140 included in the first photodetection layer 12A and In each of the second photodetection regions 142 included in the second photodetection layer 12B, the p-type semiconductor layer (p− type semiconductor layer 14A, p+ type semiconductor layer 14B) side surface is laminated as the first surface 15A. It is a configuration.

The wiring layer 36 of the optical detector 10 ₁ is connected to the through electrode 40 _1. The through electrode 40 ₁ functions as an anode electrode of the photodetector 10 ₁ . Wiring layer 36 of the optical detector 10 ₂ is connected to the through electrode 40 _2. Through electrodes 40 ₂ serves as an anode electrode of photodetector 10 _2.

In the photodetector 11A, the second photodetection layer 12B is provided between the first photodetection layer 12A and the reflective layer 20.

That is, in the photodetector 11A, the reflective layer 20, the optical detector 10 ₂ including a second light detection layer 12B, is provided on the second surface 15B side of the first light detection layer 12A.

In the optical detector 10 _2, reflective layer 20 also functions as a cathode electrode, and is connected to the through electrode 42. In the present embodiment, the electrode layer 52, the reflective layer 20, and the through electrode 42 function as a cathode electrode.

In the example shown in FIG. 5, the first photodetection region 140 included in the first photodetection layer 12A and the second photodetection region 142 included in the second photodetection layer 12B are used as the first light detection region. When projected onto the third surface parallel to the first surface 14A of the detection layer 12A, at least part of the first light detection area 140 overlaps with the second light detection area 142.

That is, the position in the arrow Y direction in FIG. 5 of at least a part of the first photodetection region 140 and the second photodetection region 142 is between the first photodetection layer 12A and the second photodetection layer 12B. Match with.

The photodetector 11A, (in FIG. 5, reference incident light L1) light from the first surface 15A side of the first light detection region 140 when the incident light is first, the first light of the optical detector 10 ₁ after entering the first light detection region 140 included in the detection layer 12A, leading to the first light detection layer 12A of the optical detector 10 _2.

The light incident to the second light detection region 142 included in the second light detection layer 12B of the optical detector 10 _2, by the reflective layer 20, a second light included in the second light detection layer 12B The light is reflected toward the first photodetection region 140 included in the first photodetection layer 12A via the detection region 142 (see reflected light L2 in FIG. 5).

In this way, by using the photodetector 11A as a laminated body including the first photodetection layer 12A and the second photodetection layer 12B, the first light arranged on the most upstream side in the light incident direction. Light (specifically, photons) that is not detected in the first photodetection region 140 included in the detection layer 12A is included in the second photodetection layer 12B disposed on the downstream side in the incident direction. The two light detection regions 142 are sequentially detected.

Here, for example, photons are incident on the first photodetection region 140 included in the first photodetection layer 12A disposed on the first layer on the upstream side in the light incident direction, and avalanche multiplication occurs. If the second photon is incident during the dead time (dead time), the multiplication phenomenon has already occurred, so that the second photon cannot be counted in the first photodetection region 140. However, the photons not detected in the first layer during the avalanche multiplication by the first layer are included in the second photodetection layer 12B arranged in the second layer, which is counted from the incident direction of light. It becomes possible to count in the light detection area 142. Therefore, the dynamic range (the number of photon counts) can be improved.

In addition, the reflective layer 20 is provided on the second surface 15B side of the second photodetection region 142 included in the second photodetection layer 12B arranged on the most downstream side in the light incident direction. For this reason, the optical path length of the light incident on each of the first photodetection region 140 and the second photodetection region 142 due to the reflection by the reflection layer 20 is made longer than that in the configuration without the reflection layer 20. You can

Therefore, the photodetector 11 of the present embodiment can obtain the same effect as that of the above-mentioned embodiment and can improve the dynamic range (the number of photon counts). Specifically, the photodetector 11 according to the present embodiment, which includes the first photodetection layer 12A, the second photodetection layer 12B, and the reflective layer 20, includes the second photodetection layer 12B. The dynamic range can be increased by 1.5 times or more as compared with the configuration in which the reflective layer 20 is not included (the photo detection layer is not laminated). Moreover, it is considered that the dynamic range can be increased by 1.67 times when three photodetection layers are laminated.

FIG. 6 shows a photodetector 11A in which four photodetection layers (having the same structure as the first photodetection layer 12A and the second photodetection layer 12B) each having a depletion layer thickness of 5 μm in the photodetection region are stacked. 6 is a diagram showing the relationship between the absorption amount of light at 850 nm in the near infrared region and the thickness of the depletion layer in FIG.

Diagram 60 shows the absorption amount (%) of light having a wavelength of 850 nm in the near infrared region.

As shown in FIG. 6, the optical detector 11A, in the depletion layer counted from the light incident side first layer of the light detection layer, as shown in the graph 62 _1, the absorption of light of a wavelength in the near-infrared region The amount was 30%. Then, in the depletion layer counted from the light incident side second layer of the optical detection layer, as shown in the graph 62 _2, the absorption of light of a wavelength in the near infrared region was 20%. Further, in the depletion layer counted from the light incident side third layer of the light detection layer, as shown in the graph 62 _3, absorption of light of a wavelength in the near infrared region is 15% of the fourth layer in the depletion layer of the light detection layer, as shown in the graph 62 _4, absorption was 10%. Note that these graphs 62 _{1-62 4} shows the cumulative value of the absorption amount of from the first layer of the light detection layer. Therefore, the actual absorption amount of each layer is a difference from the absorption amount shown by the graph in the previous stage.

In this way, by stacking a plurality of photodetection layers, light that is not detected by the photodetection layers arranged on the upstream side in the incident direction of light can be detected by the photodetection layers arranged on the downstream side. Can be said to be possible. Further, as compared with the case where the photodetector constituted by only one layer has an absorption amount of light having a wavelength in the near infrared region of 30%, the larger the number of laminated photodetection layers is, The absorption amount of light having a wavelength in the near infrared region in the photodetector 11 increased to 30%, 50%, 65%, and 75% (see diagram 60).

Further, as shown in FIG. 5, by forming the reflective layer 20 on the second surface 15C side of the second layer of the light detection layer (second photodetection layer 12B in the light detector 10 _2), photon 1 After passing through the first photodetection region 140 included in the first photodetection layer 12A of the second layer and the second photodetection region 142 included in the second photodetection layer 12B of the second layer in this order, The second photodetection area 142 included in the second photodetection layer 12B of the second layer, which is reflected by the reflective layer 20, and the first photodetection area 140 included in the first photodetection layer 12A of the first layer. Through in this order. Therefore, the photons pass through substantially four photodetection layers (photodetection regions). Therefore, it is possible to realize the same absorption efficiency as that when it is configured by the four photodetection layers.

Returning to FIG. 5, FIG. 5 shows the photodetector 11A having a structure in which the first photodetection layer 12A and the second photodetection layer 12B are laminated, but the photodetector 11A is as described above. In addition, a structure in which three or more photodetection layers are laminated may be used. Further, by forming the reflective layer 20 on the lowermost layer (closest to the second surface side) that is laminated, as described above, the optical path length may be twice the total number of products.

In addition, in FIG. 5, the surface on the p-type semiconductor layer (p− type semiconductor layer 14A, p+ type semiconductor layer 14B) side of both the first photodetection layer 12A and the second photodetection layer 12B is the first side. As the surface 15A, the photodetector 11A having a laminated structure is shown.

However, the first photodetection layer 12A (or the second photodetection layer 12B) in which the surface of the first photodetection region 140 (or the second photodetection region 142) on the p-type semiconductor layer side is the first surface 15A. ), and the second photodetection layer 12B (or the second photodetection layer) in which the surface on the n-type semiconductor substrate 14C side in the second photodetection area 142 (or the first photodetection area 140) is the first surface 15A. The region 142) may be mixed and laminated to form the photodetector 11.

FIG. 7 is a schematic diagram of the photodetector 11B.

Photodetector 11B includes an optical detector 10 _1, which includes a first optical detection layer 12A, a light detector 11 that the optical detector 10 ₃ with a second light detection layer 12B, a stacked.

Photodetector 10 _1, except without the reflective layer 20, the same configuration as the optical detector 10B shown in FIG.

In the optical detector 10 _1, the optical detector 10B shown in FIG. 2, instead of the reflecting layer 20 which also functions as a cathode electrode, and an electrode layer 52. The electrode layer 52 includes at least a part of light in the sensitivity wavelength region of the first photodetection region 140, at least a part of light in the sensitivity wavelength region of the second photodetection region 142, and at least one of near-infrared regions. It is a transparent electrode which transmits the light of a part. In the photodetector 11B, the electrode layer 52 also functions as a cathode electrode of photodetector 10 _3.

Photodetector 10 ₃ has the same configuration as the optical detector 10B shown in FIG. However, the light detector 10 ₃ is a configuration without the support substrate 39 and the adhesive layer 24. Further, the optical detector 10 _3, the laminate of the first light detection layer 12A and the insulating layer 30 in the photodetector 10B, upside down from the examples shown in FIG. 2, the electrode layer of the photodetector 10 ₁ This is a configuration arranged on the 52 side. The light detector 10 _3, instead of the first light detection layer 12A, a configuration in which a second light detection layer 12B. Therefore, the optical detector 10 _3, at the pn junction of the second light detection region 142, p-type semiconductor layer (p- type semiconductor layer 14A, p + -type semiconductor layer 14B) side of the plane next to the second surface 15B, The surface on the n-type semiconductor substrate 14C side is the first surface 15A.

In the optical detector 10 _3, the second surface 15B side of the second light detecting region 142 included in the second light detection layer 12B, i.e., the quenching resistor 32 side of the second light detection region 142, The reflective layer 20 is provided.

As described above, the photodetector 11B includes the first photodetection layer 12A in which the surface of the first photodetection region 140 on the p-type semiconductor layer side is the first surface 15A and the n in the second photodetection region 142. The second photodetection layer 12B having the first surface 15A on the side of the type semiconductor substrate 14C is laminated.

In addition, in the photodetector 11B, the second photodetection layer 12B is arranged between the first photodetection layer 12A and the reflective layer 20. That is, the reflective layer 20 is provided on the second surface 15B side of the second photodetection layer 12B among the first photodetection layer 12A and the second photodetection layer 12B provided on the photodetector 11B. There is.

The wiring layer 36 of the optical detector 10 ₁ is connected to the through electrode 40 _1. The through electrode 40 ₁ functions as an anode electrode of the photodetector 10 ₁ . Wiring layer 36 of the optical detector ₁₀₃ is connected to the through electrode 40 _2. Through electrodes 40 ₂ serves as an anode electrode of photodetector 10 _3.

The electrode layer 52 is connected to the through electrode 42. In the present embodiment, the electrode layer 52 and the penetrating electrode 42 function as the cathode electrodes of the photodetectors 10 ₁ and 10 ₃ .

The photodetector 11B, (in FIG. 7, the reference incident light L1) first light from the first surface 15A side of the light detection region 140 when the incident light is first, the first light of the optical detector 10 ₁ after entering the first light detection region 140 included in the detection layer 12A, reaching the second light detecting region 142 included in the second light detection layer 12B of the photodetector 10 _3.

The light incident to the second light detection area 142 of the optical detector 10 _3, the reflective layer 20, through the second light detecting region 142 included in the second light detection layer 12B, first The light is reflected toward the first light detection region 140 side included in the light detection layer 12A (see reflected light L2 in FIG. 7).

Therefore, like the photodetector 11A, the photodetector 11B can obtain the same effect as that of the above-described embodiment and can improve the dynamic range (the number of photon counts).

In addition, the first photodetection layer 12A in which the surface of the first photodetection region 140 on the n-type semiconductor layer 14C side is the first surface 15A, and the surface of the second photodetection region 142 on the n-type semiconductor substrate 14C side. The second photodetection layer 12B having the first surface 15A as the first surface 15A may be laminated to form the photodetector 11.

FIG. 8 is a schematic diagram showing an example of the photodetector 11C. Photodetector 11C includes an optical detector 10 ₄ with a second light detection layer 12B, a photodetector _105, which includes a first optical detection layer 12A, an optical detector 11 formed by stacking.

Photodetector 10 ₄ has the same configuration as the optical detector 10C shown in FIG.

In the optical detector 10 _4, the optical detector 10C shown in FIG. 3, the electrode layer 26, as described with reference to FIG. 3, at least a portion of the sensitive wavelength region of the first light detection region 140 It is a transparent electrode that transmits light, at least a part of light in the sensitivity wavelength region of the second light detection region 142, and at least a part of light in the near infrared region, and has the same function as the electrode layer 52. .. Wiring layer 36 of the optical detector ₁₀₄ is connected to the through electrode 40 ₄ as a through electrode 40. Through electrodes 40 ₄ functions as an anode electrode of the second light detection area 142 of the optical detector _104.

Photodetector ₁₀₅ includes a reflective layer 20, except that not provided with the supporting substrate 38, and the same configuration as the optical detector 10C shown in FIG. Wiring layer 36 of the optical detector ₁₀₅ is connected to the through electrode 40 ₅ as the through electrode 40. Through electrodes 40 ₅ functions as an anode electrode of the first light detection region 140 of the optical detector _105.

The electrode layer 26 functions as a cathode electrode. Electrode layer 26 of the optical detector _{10 4,} and the photodetector ₁₀₅ is connected to the through electrode 42.

In this way, the photodetector 11C includes the first photodetection layer 12A having the first surface 15A on the surface of the first photodetection region 140 on the n-type semiconductor substrate 14C side and the second photodetection region 142. This is a configuration in which a second photodetecting layer 12B having a surface on the n-type semiconductor substrate 14C side as the first surface 15A is laminated.

Further, in the photodetector 11C, the second photodetection layer 12B is provided between the first photodetection layer 12A and the reflective layer 20. That is, the reflection layer 20 is the first photodetection layer 12A and the second photodetection layer 12B which are arranged at the most downstream side in the direction of the second surface 15B (see the arrow XA direction in FIG. 4). Is provided on the second surface 15B side of the photodetection layer 12A.

The photodetector 11C, (in FIG. 8, reference incident light L1) light from the first surface 15A side of the first light detection region 140 when the incident light is first, the first light of the optical detector 10 ₅ after entering the first light detection region 140 included in the detection layer 12A, reaching the second light detecting region 142 included in the second light detection layer 12B of the photodetector 10 _4.

Then, the light incident on the second photodetection region 142 included in the second photodetection layer 12B of the photodetector 10 ₄ is reflected by the reflection layer 20 to the second photodetection layer 12B of the photodetector 10 ₄ . via a second light detection region 142 included, is reflected toward the first photodetection region 140 side included in the first light detection layer 12A of the optical detector ₁₀₅ (in FIG. 8, the reflected light L2 reference).

Therefore, like the photodetector 11A, the photodetector 11C can obtain the same effect as that of the above-described embodiment and can improve the dynamic range (the number of photon counts).

In the photodetector 11A, each anode electrode of the first photodetection region 140 included in the first photodetection layer 12A and the second photodetection region 142 included in the second photodetection layer 12B. In addition, the through electrode 40 ₁ and the through electrode 40 ₂ were used (see FIG. 5). However, the first photodetection region 140 included in the first photodetection layer 12A and the second photodetection region 142 included in the second photodetection layer 12B may be connected to a common anode electrode. ..

FIG. 9 is a schematic diagram showing an example of the photodetector 11D. The photodetector 11D is a stacked body of the photodetector 10 ₁ and the photodetector 10 ₂ . The optical detector 11D, the through electrode 40 ₁ of the optical detector 10 ₁ (see FIG. 5), the through electrode 40 ₂ of the optical detector 10 ₂ (see FIG. 5), was a common through-electrode 40 Other than that, the configuration is similar to that of the photodetector 11A in FIG. Note that, as shown in FIG. 9, a protective film 27 may be laminated on the reflective layer 20.

As described above, the anode electrodes of the first photodetection layer 12A and the second photodetection layer 12B may be connected to the common through electrode 40 and used.

Note that, as shown in FIGS. 5 and 7 to 8, the anode electrodes of the first photodetection layer 12A and the second photodetection layer 12B constituting the photodetector 11 are replaced with the first photodetection layer. When connecting different through electrodes 40 to each of 12A and the second photodetection layer 12B, holes corresponding to the through electrodes 40 are formed in the insulating layer 30 in a staggered manner to form the manufacturing process. It can be simplified.

FIG. 10 is an explanatory diagram of the arrangement of the through electrodes 40. As shown in FIGS. 10A and 10B, the insulating layer 30 in which the through holes corresponding to the plurality of through electrodes 40 ₁ are arranged in a staggered manner, and the through holes corresponding to the plurality of through electrodes 40 ₂ are formed in a zigzag manner. The insulating layer 30 arranged is prepared. Then, one of these two insulating layers 30 is inverted and attached to the other insulating layer 30 (see FIG. 10C). Accordingly, it is preferable to configure the photodetector 11 in which a plurality of photodetection layers (the first photodetection layer 12A and the second photodetection layer 12B) are stacked.

In the example shown in FIG. 5, the first photodetection region 140 included in the first photodetection layer 12A and the second photodetection region 142 included in the second photodetection layer 12B are first The case where at least a part of the first photodetection region 140 overlaps with the second photodetection region 142 when projected onto the third surface parallel to the first surface 15A of the photodetection layer 12A is described.

However, the first photodetection region 140 included in the first photodetection layer 12A and the second photodetection region 142 included in the second photodetection layer 12B are not included in the first photodetection layer 12A. At least a part of the first light detection area 140 may not overlap with the second light detection area 142 when projected onto the third surface parallel to the first surface 15A.

(Fifth Embodiment)
Next, a method for manufacturing the photodetector 10 according to the above embodiment will be described.

11 to 19 are explanatory views showing an example of a method of manufacturing the photodetector 10A described in the first embodiment.

As shown in FIG. 11, first, an n-type semiconductor substrate 28 is prepared. Then, the n-type semiconductor substrate 28 is subjected to a known semiconductor manufacturing process to form the first photodetection region 140. Specifically, first, the p − type semiconductor layer 14A is formed as an epitaxial layer of silicon on the n type semiconductor substrate 28 by epitaxial growth of silicon. Then, impurities (for example, boron) are implanted so that part of the p − type semiconductor layer 14A becomes the p + type semiconductor layer 14B. As a result, the plurality of first photodetection regions 140 are formed on the n-type semiconductor substrate 28. The length of each first light detection region 140 in the arrangement direction of each first light detection region 140 is, for example, 800 μm.

Next, element isolation of each first photodetection region 140 is performed so that each first photodetection region 140 does not electrically interfere with each other. The element isolation is performed by forming a region between the first photodetection regions 140, for example, a Deep Trench Isolation structure or a channel stopper structure by implanting impurities (for example, phosphorus). Due to the element isolation, the element isolation portion 29 is formed between each of the first light detection regions 140. The element isolation portion 29 reaches the region of the n-type semiconductor substrate 14C.

Next, as shown in FIG. 12, the insulating layer 30 is formed on the plurality of first light detection regions 140. Next, the reflective layer 20 is formed on the first photodetection region 140 with the insulating layer 30 interposed therebetween.

Next, as shown in FIG. 13, after forming the insulating layer 30, the quenching resistor 32 connected in series to the first light detection region 140 is formed. Next, as shown in FIG. 14, after further forming the insulating layer 30, the contact layer 34 is formed. Then, the wiring layer 36 is formed and connected to the quenching resistor 32 via the contact layer 34. Further, the electrode layer 37 is formed.

Next, as shown in FIG. 15, an insulating layer 30 is further formed and a region for forming a through electrode connected to the wiring layer 36 is patterned. Next, the support substrate 38 is formed on the insulating layer 30 (see FIG. 16).

On the other hand, by thinning the n-type semiconductor substrate 28, the first photodetection layer 12A is formed (see FIG. 17).

Further, as shown in FIG. 18, the electrode layer 26 is formed on the n-type semiconductor substrate 14C side of the first photodetection layer 12A. Further, the electrode layer 26 is connected to the electrode layer 37 via the through electrode 42. Then, as shown in FIG. 19, the through electrode 40 connected to the wiring layer 36 and the through electrode 44 connected to the electrode layer 37 are formed, thereby manufacturing the photodetector 10A.

(Sixth Embodiment)
20 to 26 are explanatory views showing an example of a method of manufacturing the photodetector 10B described in the second embodiment.

As shown in FIG. 20, first, an n-type semiconductor substrate 28 is prepared. Then, the n-type semiconductor substrate 28 is subjected to a known semiconductor manufacturing process to form the first photodetection region 140. Next, the element isolation part 29 is formed between each 1st photon detection area 140 (similar to FIG. 11 of 5th Embodiment).

Next, as shown in FIG. 21, after forming the insulating layer 30, the quenching resistor 32 connected in series to the first light detection region 140 is formed. Next, as shown in FIG. 22, the insulating layer 30 is further formed and the contact layer 34 is formed. Then, the wiring layer 36 is formed and connected to the quenching resistor 32 via the contact layer 34.

Next, as shown in FIG. 23, after further forming the insulating layer 30, the support substrate 39 is provided via the adhesive layer 24.

On the other hand, by thinning the n-type semiconductor substrate 28, the first photodetection layer 12A is formed (see FIG. 24).

Further, as shown in FIG. 25, an electrode layer 26 is formed on the n-type semiconductor substrate 14C side of the first photodetection layer 12A. Further, the electrode layer 26 is connected to the wiring layer 36 via the through electrode 40.

Next, as shown in FIG. 26, the reflective layer 20 is formed on the second surface 15B side of the first photodetection layer 12A. Thereby, the photodetector 10B is manufactured.

The photodetector 11 in which a plurality of photodetection layers (the first photodetection layer 12A and the second photodetection layer 12B) described in the fourth embodiment are stacked is manufactured by the same process as above. The photodetector 10 may be manufactured by stacking the photodetector 10 with the electrode layer 52 or the antireflection layer 54 interposed therebetween. Further, the reflective layer 20 may be arranged at the above-mentioned position. The n-type semiconductor substrate 28 may be thinned after being laminated.

Although the embodiments of the present invention have been described above, these embodiments and modifications are presented as examples, and are not intended to limit the scope of the invention. These new embodiments and modifications can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications are included in the scope and spirit of the invention, and are also included in the invention described in the claims and the scope equivalent thereto.

10, 10A, 10B, 10C, 11, 11A, 11B, 11C, 11D Photodetector 12A First photodetection layer 12B Second photodetection layer 15A First surface 15B Second surface 20 Reflective layer 32 Quenching resistor 36 Wiring layer 140 First light detection area 142 Second light detection area

Claims (12)

A light detection area having a first surface on which at least a part of light in the near infrared region is incident and a second surface opposite to the first surface, and detecting the light;
A reflection layer which is provided on the second surface side of the light detection region, includes a metal that reflects the light, and functions as an electrode;
A quenching resistor provided on the first surface side of the light detection region and connected in series to the light detection region without bump bonding,
A photodetector. The reflective layer functions as a cathode electrode,
Further comprising a through electrode connected to the quenching resistor and functioning as an anode electrode,
The photodetector according to claim 1. The photodetection region, the reflective layer, and a plurality of photodetection layers each including the quenching resistor,
The photodetector according to claim 1. The first surface is a flat surface,
The photodetector according to claim 1. The reflection layer is provided so as to cover at least a part of the photodetection region on the second surface side along an orthogonal direction orthogonal to a facing direction of the first surface and the second surface. 1. The photodetector according to 1. The reflection layer is provided so as to cover the entire area of the photodetection area on the second surface side along an orthogonal direction orthogonal to the facing direction of the first surface and the second surface,
The photodetector according to claim 1. The photodetection region according to claim 1, wherein the photodetection region includes a pn junction in which a p-type semiconductor layer containing Si as a main component and an n-type semiconductor layer containing Si as a main component are joined together. vessel. 8. The first surface is a surface of the photodetection region on the p-type semiconductor layer side of the pn junction or a surface of the photodetection region on the n-type semiconductor layer side of the pn junction. The photodetector described in. 9. The photodetector according to claim 1, further comprising an insulating layer provided on the photodetection region and including the reflective layer and the quenching resistor. The photodetector according to claim 1, wherein the metal is Al, Ti, TiN, W, Mo or an alloy thereof. A plurality of light detection regions having a first surface on which at least a part of light in the near infrared region is incident and a second surface opposite to the first surface, and detecting the light;
A plurality of reflection layers that are provided on the second surface side of each of the plurality of light detection regions and that include a metal that reflects the light;
A plurality of quenching resistors connected in series without bump bonding to each of the plurality of photodetection regions,
A photodetector. A plurality of light detection regions having a first surface on which at least a part of light in the near infrared region is incident and a second surface opposite to the first surface, and detecting the light;
A reflection layer provided on the second surface side of the light detection region so as to cover all of the plurality of light detection regions and including a metal that reflects the light;
A quenching resistor connected in series to the light detection region without via bump bonding,
A photodetector.

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