Focal plane photoelectric detector, focal plane photoelectric detector wafer, and wafer assembly

Abstract

A focal plane photoelectric detector (100), comprising a photosensitive module (10), a readout circuit module (20), and solder bumps (30). The photosensitive module (10) comprises a light-transmitting substrate (11), a pixel layer (12) disposed on one side of the light-transmitting substrate (11), and a plurality of groups of first electrodes (13) disposed on the side of the pixel layer (12) away from the light-transmitting substrate (11). The pixel layer (12) comprises a plurality of pixel units (101) arranged in an array on the light-transmitting substrate (11), each pixel unit (101) being provided with one group of first electrodes (13). Each pixel unit (101) comprises a photosensitive detection region (S1) and an electrode arrangement region (S2), and the first electrodes (13) are disposed in the electrode arrangement region (S2) of said pixel unit (101). The pixel layer (12) is a lead salt thin-film layer. The readout circuit module (20) comprises a plurality of readout circuit units (201), wherein the plurality of readout circuit units (201) correspond to the plurality of pixel units (101) on a one-to-one basis, and each readout circuit unit (201) is provided with one group of second electrodes (22) in alignment with one group of first electrodes (13). The photosensitive module (10) is disposed on the readout circuit module (20). The solder bumps (30) are used for connecting the group of second electrodes (22) of each readout circuit unit (201) to the group of first electrodes (13) of the corresponding pixel unit (101).

Description

A focal plane photodetector, a focal plane photodetection wafer and a wafer assembly TECHNICAL FIELD

[0001] The present application belongs to the field of infrared detection technology, and particularly relates to a focal plane photodetector, a focal plane photodetection wafer and a wafer assembly. BACKGROUND

[0002] A conventional infrared photoconductive focal plane photodetector generally comprises a substrate with a readout circuit and a photosensitive pixel located on the substrate. The substrate with the readout circuit generally adopts a silicon-based material substrate, and the photosensitive pixel is generally formed of a lead salt material. When forming the photosensitive pixel, a lead salt film is deposited on a wafer with a readout circuit, and the photosensitive pixel is formed by etching or the like. SUMMARY

[0003] According to an embodiment of the present application, a focal plane photodetector is provided, which comprises: a photosensitive module, comprising a light-transmitting substrate, a pixel layer arranged on one side of the light-transmitting substrate, and a plurality of first electrodes arranged on a side of the pixel layer away from the light-transmitting substrate; the pixel layer comprises a plurality of pixel units arranged in an array on the light-transmitting substrate, and each pixel unit is provided with a group of first electrodes on a side thereof away from the light-transmitting substrate; each pixel unit comprises a photosensitive detection area in a middle part and an electrode arrangement area in a periphery of the photosensitive detection area, and each group of first electrodes is arranged in the electrode arrangement area of the pixel unit; the pixel layer is a lead salt film layer; a readout circuit module comprises a plurality of readout circuit units, and each readout circuit unit corresponds to a pixel unit; each readout circuit unit has a group of second electrodes opposite to a group of first electrodes of the corresponding pixel unit; the photosensitive module is arranged on the readout circuit module, and the first electrodes of the photosensitive module are located on a side facing the readout circuit module; and a soldering stud is used to connect a group of second electrodes of each readout circuit unit and a group of first electrodes of the corresponding pixel unit.

[0004] In some embodiments, each pixel unit further comprises a reflective layer on a side thereof away from the light-transmitting substrate, and the reflective layer is arranged in the photosensitive detection area of the pixel unit.

[0005] In some embodiments, the focal plane photodetector is an infrared detector, and an infrared waveband transmittance of the light-transmitting substrate is greater than or equal to 90%.

[0006] In some embodiments, the light-transmitting substrate is a sapphire substrate, a quartz substrate or a calcium fluoride substrate.

[0007] In some embodiments, at least part of the soldering studs is initially arranged on the corresponding first electrodes.

[0008] In some embodiments, at least part of the welding studs are initially arranged on the corresponding second electrodes.

[0009] In some embodiments, at least part of the welding studs comprise a first layer of welding studs and a second layer of welding studs stacked together; wherein the first layer of welding studs are initially arranged on the corresponding first electrodes, and the second layer of welding studs are initially arranged on the corresponding second electrodes.

[0010] According to the embodiments of the present application, a focal plane photoelectric detection wafer with multiple detection unit regions is further provided, which comprises: a light-transmitting substrate; a pixel layer comprising multiple pixel units arranged in an array in each detection unit region, each pixel unit comprising a photosensitive detection region in a middle part and an electrode arrangement region in a periphery of the photosensitive detection region, the pixel layer being a lead salt thin film layer; and an electrode layer comprising multiple groups of first electrodes, each pixel unit being provided with a group of first electrodes on a side facing away from the light-transmitting substrate, each group of first electrodes being arranged in the electrode arrangement region of the pixel unit.

[0011] In some embodiments, each pixel unit further comprises a reflective layer on the side of the pixel unit facing away from the light-transmitting substrate, the reflective layer being arranged in the photosensitive detection region of the pixel unit; and / or the light-transmitting substrate has an infrared waveband transmittance greater than or equal to 90%; and / or the light-transmitting substrate is a sapphire substrate, a quartz substrate or a calcium fluoride substrate; and / or at least part of the first electrodes are provided with welding studs.

[0012] According to the embodiments of the present application, a wafer assembly is further provided, which comprises: a first wafer, which is the focal plane photoelectric detection wafer as described above; and a second wafer, which is a readout circuit wafer, the second wafer comprising multiple readout circuit modules corresponding one-to-one to the multiple detection unit regions comprised in the first wafer; each readout circuit module comprising multiple readout circuit units, the multiple readout circuit units of each readout circuit module corresponding one-to-one to the multiple pixel units of the corresponding detection unit region, each readout circuit unit having a group of second electrodes opposite to a group of first electrodes of the corresponding pixel unit, the first electrodes of the detection unit region being located on a side facing the readout circuit module; and welding studs for connecting the group of second electrodes of each readout circuit unit to the group of first electrodes of the corresponding pixel unit.

[0013] The main technical effect achieved by the embodiment of the present application is that the focal plane photoelectric detector, the focal plane photoelectric detection wafer and the wafer assembly provided by the embodiment of the present application can avoid the key parameter drift of the readout circuit caused by the formation of the pixel layer, so as to cause the circuit function failure, and is conducive to improving the preparation yield of the focal plane photoelectric detector and prolonging the service life of the focal plane photoelectric detector. BRIEF DESCRIPTION OF DRAWINGS

[0014] Fig. 1 is a sectional view of a focal plane photoelectric detector provided by an embodiment of the present application.

[0015] Fig. 2 is a sectional view of a photosensitive module provided by an embodiment of the present application.

[0016] Fig. 3 is a sectional view of a readout circuit module provided by an embodiment of the present application.

[0017] Fig. 4 is a sectional view of another photosensitive module provided by an embodiment of the present application.

[0018] Fig. 5 is a top view of a first wafer provided by an embodiment of the present application.

[0019] Fig. 6 is a top view and a partial enlarged view of a first wafer provided by an embodiment of the present application.

[0020] Fig. 7 is a top view of a second wafer provided by an embodiment of the present application.

[0021] Fig. 8 is a top view and a partial enlarged view of a second wafer provided by an embodiment of the present application.

[0022] Fig. 9 is a schematic view of bonding of the first wafer and the second wafer provided by an embodiment of the present application.

[0023] Fig. 10 is a top view and a partial enlarged view of another focal plane photoelectric detector provided by an embodiment of the present application. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments (or, the implementation manners) of the present application will be described clearly and completely in combination with the accompanying drawings. When the following description refers to the accompanying drawings, the same numerals in different drawings represent the same or similar elements unless otherwise indicated.

[0025] If the application embodiments involve terms of direction indication or positional relationship (for example, up, down, left, right, front, back, inner, outer, top, bottom, center, vertical, horizontal, longitudinal, transverse, length, width, counterclockwise, clockwise, axial, radial, circumferential, etc.), such terms are only used to explain the relative positional relationship, motion condition, etc. between components in a certain specific posture; if the specific posture changes, the direction indication or positional relationship will also change accordingly. In addition, the terms "first", "second", etc. in the application embodiments are only used for convenience of description, and cannot be understood as indicating or implying relative importance.

[0026] A conventional infrared photoconductive focal plane photodetector generally includes a substrate with readout circuit and a photosensitive pixel on the substrate. However, the wafer with readout circuit will undergo a high temperature process in thin film deposition and sensitization process, which may cause the drift of key parameters of the readout circuit and result in the failure of the circuit function. The focal plane photodetector, focal plane photodetector wafer and wafer assembly are described in detail below with reference to FIGS. 1-10.

[0027] Referring to FIG. 1, and if necessary, in combination with other drawings, the application provides a focal plane photodetector 100, which includes a photosensitive module 10 and a readout circuit module 20.

[0028] The photosensitive module 10 includes a light-transmitting substrate 11, a pixel layer 12 arranged on one side of the light-transmitting substrate 11, and a plurality of groups of first electrodes 13 arranged on the side of the pixel layer 12 away from the light-transmitting substrate 11; the pixel layer 12 includes a plurality of pixel units 101 arranged in an array on the light-transmitting substrate 11, and each pixel unit 101 is provided with a group of first electrodes 13 on the side away from the light-transmitting substrate 11; wherein each pixel unit 101 includes a photosensitive detection area S1 in the middle and an electrode arrangement area S2 on the periphery of the photosensitive detection area S1, and each group of first electrodes 13 is arranged in the electrode arrangement area S2 of the corresponding pixel unit 101; the pixel layer 12 is a lead salt thin film layer.

[0029] The readout circuit module 20 includes a plurality of readout circuit units 201, and each readout circuit unit 201 corresponds to one pixel unit 101; each readout circuit unit 201 has a group of second electrodes 22 opposite to a group of first electrodes 13 of the corresponding pixel unit 101; the photosensitive module 10 is arranged on the readout circuit module 20, and the first electrodes 13 of the photosensitive module 10 are located on the side facing the readout circuit module 20; and a group of second electrodes 22 of each readout circuit unit 201 is connected to a group of first electrodes 13 of the corresponding pixel unit 101 through a soldering stud 30.

[0030] The focal plane photodetector 100 can avoid the drift of the key parameters (such as the reference voltage, the bias current, the gain parameter, etc.) of the readout circuit caused by the formation of the pixel layer 12, so as to cause the failure of the circuit function, and is beneficial to improve the preparation yield of the focal plane photodetector 100 and improve the service life of the focal plane photodetector 100.

[0031] It should be noted that the focal plane photodetector 100 shown in FIG. 1 only exemplarily shows one pixel unit 101 and one readout circuit unit 201. The focal plane photodetector 100 can actually include a plurality of pixel units 101 and readout circuit units 201. Similarly, FIGS. 2 and 4 only exemplarily show one pixel unit 101 of the photosensitive module 10. FIG. 3 only exemplarily shows one readout circuit unit 201 of the readout circuit module 20.

[0032] The soldering convex column 30 includes but is not limited to a metal indium column and a copper ball.

[0033] In some embodiments, each of the pixel units 101 further includes a light reflection layer 14 located on the side of the pixel unit 101 away from the light-transmitting substrate 11. The light reflection layer 14 is arranged in the photosensitive detection area S1 of the pixel unit 101, further improves the photosensitivity of the photosensitive area, and improves the photosensitive effect of the device.

[0034] The light reflection layer 14 can be a metal thin film layer. The material of the light reflection layer 14 can be a metal material, such as a metal gold material. Accordingly, the light reflection layer 14 is a gold thin film layer.

[0035] In some embodiments, the focal plane photodetector 100 is an infrared detector, and the infrared waveband transmittance of the light-transmitting substrate 11 is greater than or equal to 90%, so as to ensure the photosensitivity of the pixel.

[0036] In some embodiments, the light-transmitting substrate 11 is a sapphire substrate, a quartz substrate, or a calcium fluoride substrate, which can well overcome the thermal mismatch problem caused by the large difference in the thermal expansion coefficient between the lead salt thin film layer and the silicon substrate, reduce the thermal mismatch problem between the lead salt thin film layer and the silicon substrate, and improve the quality of the photosensitive module.

[0037] In some embodiments, at least part of the solder bumps 30 connecting the first electrodes 13 and the second electrodes 22 of each group are arranged on the corresponding first electrodes 13. For example, as shown in FIG. 2, the solder bumps 30 are arranged on the corresponding first electrodes 13. Accordingly, the second electrodes 22 corresponding to the first electrodes 13 with the solder bumps 30 in the readout circuit module 20 are not provided with the solder bumps, and are connected to the corresponding first electrodes 13 through the solder bumps 30 arranged on the first electrodes 13.

[0038] In some embodiments, at least part of the solder bumps 30 connecting the first electrodes 13 and the second electrodes 22 of each group are arranged on the corresponding second electrodes 22. For example, as shown in FIG. 3, the solder bumps 30 are arranged on the corresponding second electrodes 22. Accordingly, the first electrodes 13 corresponding to the second electrodes 22 with the solder bumps 30 in the photosensitive module 10 are not provided with the solder bumps, and are connected to the corresponding second electrodes 22 through the solder bumps 30 arranged on the second electrodes 22, such as the photosensitive module 10' shown in FIG. 4.

[0039] In some embodiments, at least part of the solder bumps 30 connecting the first electrodes 13 and the second electrodes 22 of each group include a first layer of solder bumps and a second layer of solder bumps stacked together; wherein the first layer of solder bumps is arranged on the corresponding first electrodes 13, and the second layer of solder bumps is arranged on the corresponding second electrodes 22.

[0040] In addition, the space between the solder bumps 30 is filled with filling glue to stabilize and solidify the structure.

[0041] According to the embodiments of the present application, as shown in FIG. 6, another photosensitive focal plane array wafer 1000 with a plurality of detection unit regions 1 is provided, which includes a light-transmitting substrate 11, a pixel layer 12, and an electrode layer.

[0042] The pixel layer 12 includes a plurality of pixel units 101 arranged in an array in each detection unit region 1, each pixel unit 101 includes a photosensitive detection area S1 in the middle and an electrode arrangement area S2 around the photosensitive detection area S1, and the pixel layer 12 is a lead salt thin film layer. Each detection unit region 1 forms a corresponding photosensitive module 10 after dicing.

[0043] The electrode layer includes a plurality of groups of first electrodes 13, each pixel unit 101 is provided with a group of first electrodes 13 on the side away from the light-transmitting substrate 11, and each group of first electrodes 13 is arranged on the electrode arrangement area S2 of the corresponding pixel unit 101.

[0044] In some embodiments, each of the pixel units 101 further comprises a reflective layer 14 on the side of the pixel unit 101 away from the light-transmitting substrate 11, and the reflective layer 14 is arranged on the light-sensitive detection area S1 of the pixel unit 101.

[0045] In some embodiments, the light-transmitting substrate 11 has an infrared waveband transmittance greater than or equal to 90%.

[0046] In some embodiments, the light-transmitting substrate 11 is a sapphire substrate, a quartz substrate, or a calcium fluoride substrate, which can well overcome the thermal mismatch problem caused by the large difference in thermal expansion coefficient between the lead salt film layer and the silicon substrate, reduce the thermal mismatch problem between the lead salt film layer and the silicon substrate, and improve the quality of the light-sensitive module.

[0047] In some embodiments, at least part of the first electrode 13 is provided with a soldering bump 30.

[0048] According to the embodiments of the present application, a wafer assembly is further provided, which comprises a first wafer 1000 and a second wafer 2000. The first wafer 1000 is a focal plane photodetector wafer 1000 as described above. The second wafer 2000 is a readout circuit wafer, which comprises a plurality of readout circuit modules 20 corresponding to the plurality of detection unit regions 1 one-to-one. Each readout circuit module 20 comprises a plurality of readout circuit units 201, the plurality of readout circuit units 201 of each readout circuit module 20 correspond to the plurality of pixel units 101 of the corresponding detection unit region 1 one-to-one, and each readout circuit unit 201 has a group of second electrodes 22 opposite to a group of first electrodes 13 of the corresponding pixel unit 101. The first electrodes 13 of the detection unit region 1 are located on the side facing the readout circuit module 20, and the group of second electrodes 22 of each readout circuit unit 201 is connected to the group of first electrodes 13 of the corresponding pixel unit 101 through a soldering bump 30.

[0049] In combination with FIGS. 5 to 10, the focal plane photodetector 100 or similar focal plane photodetector can be specifically prepared by the following method.

[0050] As shown in FIG. 5, a first wafer wafer 1001 can be provided first.

[0051] The first wafer wafer 1001 can be a sapphire, quartz, calcium fluoride, or the like, which has high light transmittance in the visible light and infrared waveband.

[0052] As shown in FIG. 6, a pixel layer, a first electrode 13, and a reflective layer 14 can be arranged on the first wafer wafer 1001 to form a first wafer 1000.

[0053] Specifically, first, lead salt film growth and pixelization are performed on the surface of the first wafer blank 1001 to form a pixel layer.

[0054] The lead salt film can be grown or prepared in various ways.

[0055] In some embodiments, a chemical bath deposition (CBD) method can be used to form the lead salt film. For example, to form a PbSe film, a lead source, a selenium source, a base source, an iodine source, and deionized water can be prepared into a mother liquor for film deposition according to a fixed ligand. A prepared first wafer blank 1001 can be placed into the mother liquor in parallel with the bottom of the container using a fixed clamp. The ambient temperature can be set to 60-90°C. After standing for 3-3.5 hours, the substrate can be taken out and washed with deionized water to obtain a PbSe film covering the first wafer blank 1001. Further, the PbSe film can be subjected to photolithography pixelization. The prepared PbSe film can be placed in a sealed sensitization chamber. The temperature in the chamber can be set to a preset temperature. Oxygen and oxygen / iodine vapor mixed gas can be sequentially introduced into the sealed chamber to complete the sensitization of the PbSe film, thereby forming a lead salt photosensitive film.

[0056] In this embodiment, the first wafer blank 1001 can be a substrate wafer of an 8-inch substrate. The preset temperature can be 380°C.

[0057] The lead source can include, but is not limited to, lead acetate, lead chloride, and / or lead nitrate.

[0058] The selenium source can include, but is not limited to, selenium powder and / or selenium urea.

[0059] The base source can include, but is not limited to, sodium hydroxide, potassium hydroxide, sodium carbonate, and / or lithium hydroxide.

[0060] The iodine source can include, but is not limited to, elemental iodine, potassium iodide, ammonium iodide, and / or potassium iodate.

[0061] In other embodiments, a quantum dot spin coating film forming method can be used to form the lead salt film. For example, to form a PbSe quantum dot film, PbSe quantum dots can be prepared by thermal injection, and configured into ink with a PbSe quantum dot concentration of 50 mg / ml. The quantum dot ink can be spin coated onto the surface of the first wafer blank 1001 by layer-by-layer spin coating for 20 times to form a film. The spin-coated quantum dot film can be annealed on a hot plate, for example, at a temperature of 100°C for 2 minutes. The quantum dot film does not need to be subjected to photolithography pixelization.

[0062] The quantum dots can include different sizes of quantum dots with an absorption wavelength of 900-2000 nm.

[0063] The quantum dot ink solvent includes, but is not limited to, n-hexane, n-octane, n-heptane, nonane, butylamine, toluene, chloroform, N,N-dimethylformamide, dimethyl sulfoxide.

[0064] In yet some embodiments, the lead salt film can be formed by physical vapor deposition. For example, to form a PbSe film, a PbSe bulk material with a purity greater than 99.99% can be placed in a molybdenum boat, the molybdenum boat is placed in a vacuum chamber with a vacuum degree of 2 -4 torr, a first wafer 1001 is fixed on a rotating disc above the vacuum chamber, and a PbSe film is evaporated at an evaporation rate of 2-4 A / s. The PbSe film is then pixelated by photolithography, and the prepared PbSe film is placed in a sealed sensitization chamber. The temperature in the chamber is set to 380℃, and oxygen and oxygen / iodine vapor mixture are sequentially introduced into the sealed chamber. The PbSe film is sensitized, and a lead salt photosensitive film is formed.

[0065] Subsequently, a first electrode 13 and a reflective layer 14 are formed, and the first wafer 1000 is formed.

[0066] The electrode metal layer can be further formed on the wafer on which the lead salt photosensitive film is formed, and the first electrode 13 is formed by pixelated etching.

[0067] The first electrode 13 includes, but is not limited to, gold, silver, chromium, nickel, and indium. The preparation method of the electrode metal layer includes, but is not limited to, thermal evaporation deposition, electron beam deposition, magnetron sputtering deposition, and physical vapor deposition.

[0068] The reflective layer 14 can also be formed by forming a corresponding material layer and pixelated etching.

[0069] As shown in FIG. 7, a second wafer 2001 can be provided.

[0070] As shown in FIG. 8, a plurality of readout circuit modules 20 and a second electrode 22 can be formed on the second wafer 2001 to form a second wafer 2000.

[0071] After the first electrode 13 is formed and / or after the second electrode 22 is formed, a solder bump 30 can be provided on at least one of the first electrode 13 and the second electrode 22 as needed.

[0072] It should be noted that the order of forming the first wafer 1000 and forming the second wafer 2000 is not limited.

[0073] As shown in FIG. 9, the first wafer 1000 and the second wafer 2000 are bonded to form a wafer assembly.

[0074] The first wafer 1000 and the second wafer are bonded in a flip-chip manner.

[0075] Subsequently, the filling glue is arranged between the soldering studs 30 in the bonded wafer assembly to stabilize and solidify the structure.

[0076] As shown in FIG. 10, the wafer assembly is cut to form a plurality of focal plane photodetectors 100 or similar focal plane photodetectors.

[0077] It should be noted that the technical solutions or technical features described in the above embodiments can be combined or supplemented with each other without conflict. The scope of protection of the present application is not limited to the precise structures described in the above embodiments and shown in the accompanying drawings. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the scope of protection of the present application.

Claims

1. A focal plane photodetector, comprising: a photosensitive module, comprising a light-transmitting substrate, a pixel layer arranged on one side of the light-transmitting substrate, and a plurality of groups of first electrodes arranged on a side of the pixel layer away from the light-transmitting substrate; the pixel layer comprises a plurality of pixel units arranged in an array on the light-transmitting substrate, each pixel unit being provided with a group of first electrodes on a side thereof away from the light-transmitting substrate; each pixel unit comprises a photosensitive detection region in a middle portion and an electrode arrangement region in a periphery of the photosensitive detection region, and each group of first electrodes is arranged in the electrode arrangement region of the pixel unit; the pixel layer is a lead salt thin film layer; a readout circuit module, comprising a plurality of readout circuit units, each readout circuit unit having a group of second electrodes opposite to a group of first electrodes of a corresponding pixel unit; the photosensitive module is arranged on the readout circuit module, and the first electrodes of the photosensitive module are located on a side thereof facing the readout circuit module; a soldering stud for connecting each group of second electrodes of a readout circuit unit to a group of first electrodes of a corresponding pixel unit.

2. The focal plane photodetector of claim 1, wherein, Each pixel unit further comprises a light-reflecting layer on a side thereof away from the light-transmitting substrate, and the light-reflecting layer is arranged in the photosensitive detection region of the pixel unit.

3. The focal plane photodetector of claim 1, wherein, The focal plane photodetector is an infrared detector, and the light-transmitting substrate has an infrared waveband transmittance greater than or equal to 90%.

4. The focal plane photodetector of claim 1, wherein, The light-transmitting substrate is a sapphire substrate, a quartz substrate or a calcium fluoride substrate.

5. The focal plane photodetector of claim 1, wherein, At least part of the soldering studs are arranged on the corresponding first electrodes.

6. The focal plane photodetector of claim 1, wherein, At least part of the soldering studs are arranged on the corresponding second electrodes.

7. The focal plane photodetector of claim 1, wherein, At least part of the soldering studs comprise a first layer of soldering studs and a second layer of soldering studs stacked together; the first layer of soldering studs is arranged on the corresponding first electrodes, and the second layer of soldering studs is arranged on the corresponding second electrodes. 8.A focal plane photodetector wafer having a plurality of detection unit regions, comprising: a light-transmitting substrate; a pixel layer, the pixel layer comprising a plurality of pixel units arranged in an array in each detection unit region, each pixel unit comprising a photosensitive detection region in a middle portion and an electrode arrangement region in a periphery of the photosensitive detection region, and the pixel layer being a lead salt thin film layer; an electrode layer comprising a plurality of groups of first electrodes, each pixel unit being provided with a group of first electrodes on a side thereof away from the light-transmitting substrate, and each group of first electrodes being arranged in the electrode arrangement region of the pixel unit.

9. The focal plane photodetecting wafer of claim 8, wherein, Each pixel unit further comprises a light-reflecting layer on a side thereof away from the light-transmitting substrate, and the light-reflecting layer is arranged in the photosensitive detection region of the pixel unit; and / or the light-transmitting substrate has an infrared waveband transmittance greater than or equal to 90%; and / or the light-transmitting substrate is a sapphire substrate, a quartz substrate or a calcium fluoride substrate; and / or at least part of the first electrodes are provided with soldering studs. 10.A wafer assembly, comprising: a first wafer, the first wafer being the focal plane photodetector wafer according to claim 8 or 9. A second wafer, which is a readout circuit wafer, comprises a plurality of readout circuit modules corresponding to a plurality of detection unit regions included in the first wafer; each readout circuit module comprises a plurality of readout circuit units corresponding to a plurality of pixel units of the corresponding detection unit region; each readout circuit unit has a set of second electrodes opposite to a set of first electrodes of the corresponding pixel unit; the first electrodes of the detection unit region are located on a side facing the readout circuit module. A soldering stud is used to connect the set of second electrodes of each readout circuit unit and the set of first electrodes of the corresponding pixel unit.

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