Dual-band image sensor wafer and dual-band image sensor

Abstract

The utility model provides a dual-band image sensor wafer and a dual-band image sensor. The dual-band image sensor wafer comprises a first acceptor substrate, a first bonding layer, an ultraviolet sensing layer, a third bonding layer and a short-wave infrared sensing layer which are stacked in sequence. And the material of the short-wave infrared sensing layer at least comprises germanium. Therefore, the first acceptor substrate, the first bonding layer and the third bonding layer form a resonant cavity in the vertical direction, and the performance of the ultraviolet image sensor can be improved. The germanium serving as the short-wave infrared sensing layer has excellent photoelectric response in the short-wave infrared band, the manufacturing process is compatible with the CMOS process, and the carrier mobility is high. And the short-wave infrared sensing layer and the ultraviolet sensing layer are separated through the third bonding layer, so that the problems of lattice mismatch and thermal mismatch existing in an interface of the short-wave infrared sensing layer and the ultraviolet sensing layer are solved, and the dual-waveband image sensor wafer with reduced cost and high performance is further realized.

Description

Technical Field

[0001] The present invention relates to the field of semiconductors, and in particular to a dual-band image sensor wafer and a dual-band image sensor. Background Art

[0002] The ultraviolet-shortwave infrared dual-band image sensor has the characteristics of wide spectral sensitivity. The spectral response range can cover the ultraviolet band (100-400nm) and the shortwave infrared band (1000-2500nm). It has the ability of multifunctional imaging and has very important applications in medical imaging, industrial detection, security, astronomy, aerospace and other fields. According to the architecture of the dual-band image sensor, it can be divided into a monolithic dual-band image sensor and a hybrid dual-band image sensor. Compared with the monolithic dual-band image sensor, the hybrid dual-band image sensor usually needs to combine the ultraviolet image sensor and the shortwave infrared image sensor, involving complex alignment and integration technology. Therefore, the application of the monolithic dual-band image sensor is more extensive. The structure of the monolithic dual-band image sensor is relatively simple, and only the ultraviolet sensing layer and the shortwave infrared sensing layer need to be integrated in a single image sensor. The materials of the common ultraviolet sensing layer and short-wave infrared sensing layer are Si and InGaAs respectively, but the two have great lattice mismatch, thermal mismatch and polarity mismatch. InGaAs is usually formed on indium phosphide (InP) wafers, which have prominent technical bottlenecks such as fragility, small wafer size, high raw material cost, and incompatibility with standard complementary metal oxide semiconductor (CMOS) manufacturing process.

[0003] That is to say, current dual-band image sensors have the problems of high cost and poor performance. Utility Model Content

[0004] In view of this, the purpose of the present application is to provide a dual-band image sensor wafer and a dual-band image sensor, which can achieve a dual-band image sensor wafer with reduced cost and high performance, and a high-performance dual-band image sensor manufactured using a high-performance dual-band image sensor wafer.

[0005] The present application provides a dual-band image sensor wafer, comprising a first acceptor substrate, a first bonding layer, an ultraviolet sensing layer, a third bonding layer and a short-wave infrared sensing layer stacked in sequence;

[0006] The ultraviolet sensing layer is a semiconductor material that absorbs ultraviolet waves, and the short-wave infrared sensing layer is a semiconductor material that absorbs infrared waves; the material of the short-wave infrared sensing layer at least includes germanium.

[0007] Optionally, the material of the ultraviolet sensing layer is silicon.

[0008] Optionally, the first acceptor substrate is a glass substrate or a sapphire substrate.

[0009] Optionally, the short-wave infrared sensing layer is an intrinsic layer, and a material of the intrinsic layer is germanium, germanium-tin or silicon-germanium-tin.

[0010] Optionally, the short-wave infrared sensing layer is a stacked layer, which is formed by alternately stacking a first target layer and a second target layer, the first target layer is a germanium layer or a germanium-tin layer, and the second target layer is a germanium-silicon layer, a germanium-tin layer or a silicon-germanium-tin layer.

[0011] Optionally, the thickness of the ultraviolet sensing layer is 20-30 nm.

[0012] Optionally, the short-wave infrared sensing layer has a thickness of 500-1000 nm.

[0013] The present application provides a dual-band image sensor, comprising: a bonded dual-band imaging chip and a readout circuit wafer;

[0014] The dual-band imaging chip is manufactured using a dual-band image sensor wafer, and the dual-band image sensor wafer includes a first acceptor substrate, a first bonding layer, an ultraviolet sensing layer, a third bonding layer, and a short-wave infrared sensing layer stacked in sequence; the ultraviolet sensing layer is a semiconductor material that absorbs the ultraviolet band, and the short-wave infrared sensing layer is a semiconductor material that absorbs the infrared band; the material of the short-wave infrared sensing layer at least includes germanium;

[0015] The dual-band imaging chip comprises an ultraviolet sensing region and a short-wave infrared sensing region, the ultraviolet sensing region comprises a first opening, the first opening is obtained by etching the short-wave infrared sensing layer, the ultraviolet sensing layer of the ultraviolet sensing region comprises a first N-type region and a first P-type region, the short-wave infrared sensing layer of the short-wave infrared sensing region comprises a second N-type region and a second P-type region, the first P-type region and the second P-type region are electrically connected by a first electrode, a first interconnection layer and a second electrode, the first N-type region and the second N-type region are electrically connected by a third electrode, a second interconnection layer and a fourth electrode; the first interconnection layer is electrically led out by a P-type electrode, and the second interconnection layer is electrically led out by an N-type electrode;

[0016] The readout circuit wafer is electrically connected to the P-type electrode and the N-type electrode respectively.

[0017] Optionally, the dual-band image sensor further comprises a surface passivation layer;

[0018] The surface passivation layer is disposed between the short-wave infrared sensing layer and the first interconnection layer, and the surface passivation layer covers the first opening.

[0019] Optionally, the material of the ultraviolet sensing layer is silicon; and the first receptor substrate is a glass substrate or a sapphire substrate.

[0020] The present application provides a dual-band image sensor wafer, comprising a first acceptor substrate, a first bonding layer, an ultraviolet sensing layer, a third bonding layer and a short-wave infrared sensing layer stacked in sequence. The ultraviolet sensing layer is a semiconductor material that absorbs the ultraviolet band, the short-wave infrared sensing layer is a semiconductor material that absorbs the infrared band, and the material of the short-wave infrared sensing layer includes at least germanium. It can be seen that the first acceptor substrate, the first bonding layer on the first acceptor substrate and even the third bonding layer of the ultraviolet sensing layer are all excellent insulators, forming a resonant cavity in the vertical direction, which is beneficial to improving the dark current, peak responsivity, quantum efficiency and operating speed of the ultraviolet image sensor. Germanium as a short-wave infrared sensing layer has excellent photoelectric response in the short-wave infrared band, the manufacturing process is compatible with the CMOS process, and the carrier mobility is high. For the short-wave infrared image sensor, the third bonding layer, the ultraviolet sensing layer and the first bonding layer below the short-wave infrared sensing layer also form a resonant cavity in the vertical direction, which is beneficial to improving the dark current, peak responsivity, quantum efficiency and operating speed of the short-wave infrared image sensor. In addition, the short-wave infrared sensing layer and the ultraviolet sensing layer are separated by a third bonding layer, which solves the problems of lattice mismatch and thermal mismatch at the interface between the short-wave infrared sensing layer and the ultraviolet sensing layer, and further realizes a cost-reduced and high-performance dual-band image sensor wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 A schematic structural diagram of a dual-band image sensor wafer provided in an embodiment of the present application is shown;

[0023] Figure 2 A schematic flow chart of a method for manufacturing a dual-band image sensor wafer provided in an embodiment of the present application is shown;

[0024] Figure 3-Figure 9 A schematic structural diagram of a dual-band image sensor wafer manufactured by a method for manufacturing a dual-band image sensor wafer provided in an embodiment of the present application is shown;

[0025] Fig.10A schematic diagram of the structure of a dual-band image sensor provided by an embodiment of the present application is shown;

[0026] Fig.11 A schematic diagram showing a process of a method for manufacturing a dual-band image sensor provided by an embodiment of the present application is shown;

[0027] Figure 12-16 A structural schematic diagram of a dual-band image sensor manufactured by a method for manufacturing a dual-band image sensor provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0029] In the following description, many specific details are set forth to facilitate a full understanding of the present application, but the present application may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0030] This application is described in detail with reference to schematic diagrams. When describing the embodiments of this application in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of this application. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0031] The monolithic dual-band image sensor includes an ultraviolet sensing layer and a short-wave infrared sensing layer. The materials of the conventional ultraviolet sensing layer and the short-wave infrared sensing layer are Si and InGaAs, respectively, but the two have great lattice mismatch, thermal mismatch and polarity mismatch. InGaAs is usually formed on an Indium Phosphide (InP) wafer, which has prominent technical bottlenecks such as fragility, small wafer size, high raw material cost, and incompatibility with the standard Complementary Metal Oxide Semiconductor (CMOS) manufacturing process.

[0032] That is to say, current dual-band image sensors have the problems of high cost and poor performance.

[0033] Based on this, the present application provides a dual-band image sensor wafer, including a first acceptor substrate, a first bonding layer, an ultraviolet sensing layer, a third bonding layer and a short-wave infrared sensing layer stacked in sequence. The ultraviolet sensing layer is a semiconductor material that absorbs the ultraviolet band, and the short-wave infrared sensing layer is a semiconductor material that absorbs the infrared band. The material of the short-wave infrared sensing layer includes at least germanium. It can be seen that the first acceptor substrate, the first bonding layer on the first acceptor substrate and even the third bonding layer of the ultraviolet sensing layer are all excellent insulators, forming a resonant cavity in the vertical direction, which is beneficial to improving the dark current, peak responsivity, quantum efficiency and operating speed of the ultraviolet image sensor. Germanium as a short-wave infrared sensing layer has excellent photoelectric response in the short-wave infrared band, the manufacturing process is compatible with the CMOS process, and the carrier mobility is high. For the short-wave infrared image sensor, the third bonding layer, the ultraviolet sensing layer and the first bonding layer below the short-wave infrared sensing layer also form a resonant cavity in the vertical direction, which is beneficial to improving the dark current, peak responsivity, quantum efficiency and operating speed of the short-wave infrared image sensor. In addition, the short-wave infrared sensing layer and the ultraviolet sensing layer are separated by a third bonding layer, which solves the problems of lattice mismatch and thermal mismatch at the interface between the short-wave infrared sensing layer and the ultraviolet sensing layer, and further realizes a cost-reduced and high-performance dual-band image sensor wafer.

[0034] In order to better understand the technical solution and technical effects of the present application, specific embodiments will be described in detail below with reference to the accompanying drawings.

[0035] See also Figure 1 , which is a schematic diagram of the structure of a dual-band image sensor wafer provided in an embodiment of the present application.

[0036] The dual-band image sensor wafer 1000 provided in this embodiment includes a first acceptor substrate 200 , a first bonding layer 110 , an ultraviolet sensing layer 120 , a third bonding layer 430 and a short-wave infrared sensing layer 410 which are stacked in sequence.

[0037] The ultraviolet sensing layer 120 is a semiconductor material that absorbs ultraviolet waves, and the short-wave infrared sensing layer 410 is a semiconductor material that absorbs infrared waves. The material of the short-wave infrared sensing layer 410 at least includes germanium.

[0038] In actual applications, a second bonding layer 210 is also formed on the first acceptor substrate 200, and a fourth bonding layer 310 is also provided between the ultraviolet sensing layer 120 and the third bonding layer 430, that is, the dual-band image sensor wafer 1000 includes a first acceptor substrate 200, a second bonding layer 210, a first bonding layer 110, an ultraviolet sensing layer 120, a fourth bonding layer 310, a third bonding layer 430 and a short-wave infrared sensing layer 410 stacked in sequence.

[0039] It can be seen that the first acceptor substrate, the first bonding layer on the first acceptor substrate, the second bonding layer, and even the third bonding layer and the fourth bonding layer of the ultraviolet sensing layer are all excellent insulators, forming a resonant cavity in the vertical direction, which is beneficial to improving the dark current, peak responsivity, quantum efficiency and operating speed of the ultraviolet image sensor. Germanium as a short-wave infrared sensing layer has excellent photoelectric response in the short-wave infrared band, the manufacturing process is compatible with the CMOS process, and the carrier mobility is high. For the short-wave infrared image sensor, the third bonding layer and the fourth bonding layer under the short-wave infrared sensing layer, the ultraviolet sensing layer, and the first bonding layer and the second bonding layer also form a resonant cavity in the vertical direction, which is beneficial to improving the dark current, peak responsivity, quantum efficiency and operating speed of the short-wave infrared image sensor. In addition, the short-wave infrared sensing layer and the ultraviolet sensing layer are separated by the third bonding layer, which solves the lattice mismatch and thermal mismatch problems at the interface between the short-wave infrared sensing layer and the ultraviolet sensing layer, and further realizes a cost-reduced and high-performance dual-band image sensor wafer.

[0040] Based on the dual-band image sensor wafer provided in the above embodiment, the embodiment of the present application further provides a method for manufacturing the dual-band image sensor wafer, and its working principle is described in detail below with reference to the accompanying drawings.

[0041] See also Figure 2 , which is a schematic flow chart of a method for manufacturing a dual-band image sensor wafer provided in an embodiment of the present application.

[0042] The method for manufacturing a dual-band image sensor wafer provided in this embodiment includes the following steps:

[0043] S101, providing a first donor substrate and a first acceptor substrate.

[0044] In the embodiment of the present application, a first donor substrate 100 and a first acceptor substrate 200 may be obtained, referring to Figure 3 As shown, the first donor substrate 100 may be a semiconductor material that absorbs ultraviolet wavelengths, and an ultraviolet sensing layer 120 may be formed subsequently.

[0045] As an example, the material of the first donor substrate 100 may be Si, GaN, InGaN, AlGaN, ZnO, Ga2O3, AlGaO or InGaO.

[0046] Considering the compatibility with CMOS process and material cost factors, the material of the first donor substrate 100 may be silicon, so that the material of the ultraviolet sensing layer 120 formed by subsequently processing the first donor substrate 100 is also silicon.

[0047] The first acceptor substrate 200 can be used as a supporting structure for the subsequent ultraviolet sensing layer 120. Considering that the first acceptor substrate 200 has less absorption of light waves, which will improve the performance of the subsequent dual-band image sensor, the first acceptor substrate 200 can be made of a transparent material, so that the first acceptor substrate 200 is highly transparent in both the ultraviolet band and the short-wave infrared band, which is beneficial to the formation of a back-illuminated ultraviolet-short-wave infrared dual-band image sensor. In addition, the first acceptor substrate 200 of a transparent material has the characteristics of low absorption and low scattering in the ultraviolet band and the short-wave infrared band, ensuring that the ultraviolet-short-wave infrared dual-band image sensor has extremely high light collection efficiency, reducing signal loss and noise, and improving the sensitivity and accuracy of the image sensor.

[0048] Specifically, the first acceptor substrate 200 may be a glass substrate or a sapphire substrate.

[0049] In the embodiment of the present application, a first bonding layer 110 is formed on one side surface of the first donor substrate 100, and the first bonding layer 110 is used to achieve bonding with the first acceptor substrate 200. The material of the first bonding layer 110 can be aluminum oxide. As an example, the thickness of the first bonding layer 110 can be 10nm.

[0050] In practical applications, a second bonding layer 210 is formed on one side surface of the first acceptor substrate 200. Figure 3 As shown, the bonding difficulty is reduced and the bonding strength is improved. The material of the second bonding layer 210 can be aluminum oxide. As an example, the thickness of the first bonding layer 110 can be 10 nm.

[0051] S102 , bonding the first donor substrate and the first acceptor substrate with the first bonding layer facing the first acceptor substrate.

[0052] In the embodiment of the present application, after forming the first bonding layer 110 on the first donor substrate 100 and obtaining the first acceptor substrate 200, direct wafer bonding (Direct Wafer-bonding) can be performed on the first donor substrate 100 and the first acceptor substrate 200. Specifically, during bonding, the first donor substrate 100 and the first acceptor substrate 200 are bonded in a direction where the first bonding layer 110 faces the first acceptor substrate 200.

[0053] refer to Figure 4 As shown, since a second bonding layer 210 is also formed on the first acceptor substrate 200, when the first donor substrate 100 and the first acceptor substrate 200 are bonded, the bonding is performed in the direction of the first bonding layer 110 toward the second bonding layer 210. After bonding, the first bonding layer 110 and the second bonding layer 210 are in direct contact.

[0054] S103, removing a portion of the thickness of the first donor substrate to obtain an ultraviolet sensing layer, and the first acceptor substrate, the first bonding layer and the ultraviolet sensing layer constitute a second acceptor substrate.

[0055] In the embodiment of the present application, after the first donor substrate 100 and the first acceptor substrate 200 are bonded, a portion of the thickness of the first donor substrate 100 can be removed to obtain the ultraviolet sensing layer 120. The first acceptor substrate 200, the first bonding layer 110 and the ultraviolet sensing layer 120 constitute the second acceptor substrate 300. Figure 5 shown.

[0056] Specifically, a portion of the thickness of the first donor substrate 100 may be removed by using a back thinning process, a chemical mechanical polishing (CMP) process, a dry etching process, or a wet etching process.

[0057] As an example, when the material of the ultraviolet sensing layer 120 is silicon, the penetration depth of the ultraviolet light signal in silicon is about 20-30 nm. Therefore, after removing a portion of the first donor substrate 100, the thickness of the obtained ultraviolet sensing layer 120 is 20-30 nm.

[0058] S104, providing a second donor substrate, and forming a short-wave infrared sensing layer on the second donor substrate.

[0059] In an embodiment of the present application, a second donor substrate 400 may be obtained, and a short-wave infrared sensing layer 410 may be formed on the second donor substrate 400 . The material of the short-wave infrared sensing layer 410 is a semiconductor material that absorbs infrared bands.

[0060] As an example, the material of the short-wave infrared sensing layer 410 may be InGaAs, MCT or PbS colloidal quantum dots.

[0061] Considering compatibility with CMOS process and material cost factors, the material of the short-wave infrared sensing layer 410 may include germanium (Ge). Germanium is a Group IV semiconductor material, has excellent photoelectric response in the short-wave infrared band, and its manufacturing process is compatible with CMOS process, can be silicon-based epitaxial, and has high carrier mobility.

[0062] As an example, the second donor substrate 400 may be a silicon substrate, and when the material of the short-wave infrared sensing layer 410 may include germanium, the short-wave infrared sensing layer 410 may be easily formed on the silicon substrate. The thickness of the short-wave infrared sensing layer 410 is 500-1000 nm.

[0063] In the embodiment of the present application, the short-wave infrared sensing layer 410 may be composed of a single film layer, or may be composed of a plurality of stacked film layers, that is, the short-wave infrared sensing layer 410 may be an intrinsic layer or a stacked layer, which is described in detail below:

[0064] In some embodiments, the short-wave infrared sensing layer 410 may be an intrinsic layer, and the material of the intrinsic layer includes germanium, and may also include other Group IV materials except germanium. For example, the material of the intrinsic layer may be germanium, germanium tin (GeSn) or silicon germanium tin (SiGeSn).

[0065] In some embodiments, the short-wave infrared sensing layer 410 may be a stacked layer, and the stacked layer is formed by alternately stacking a first target layer and a second target layer. In this way, the first target layer and the second target layer are alternately stacked to form a quantum well structure, thereby improving the photosensitivity of the short-wave infrared sensing layer 410. The first target layer is a germanium layer or a germanium tin layer, and the second target layer is a germanium silicon (GeSi) layer, a germanium tin layer, or a silicon germanium tin layer.

[0066] As an example, the first target layer is a germanium layer, and the second target layer is a germanium-tin layer.

[0067] As another example, the first target layer is a germanium layer, and the second target layer is a silicon-germanium-tin layer.

[0068] As yet another example, the first target layer is a germanium-tin layer, and the second target layer is a silicon-germanium-tin layer.

[0069] As yet another example, the first target layer is a germanium layer, and the second target layer is a germanium silicon layer.

[0070] In the embodiment of the present application, in order to improve the crystal quality of the short-wave infrared sensing layer 410, a buffer layer 420 may be first formed on one side of the second donor substrate 400, and then the short-wave infrared sensing layer 410 may be formed on one side of the buffer layer 420. Figure 6 As shown. The buffer layer 420 can be used as a buffer film layer between the second donor substrate 400 and the short-wave infrared sensing layer 410 to form a short-wave infrared sensing layer 410 with higher crystal quality. The material of the buffer layer 420 may include germanium, and the buffer layer 420 may be formed using a low-temperature process. For example, the thickness of the buffer layer 120 may be 100-500nm.

[0071] In practical applications, in order to further improve the crystal quality of the short-wave infrared sensing layer 410 , the second donor substrate 400 may be a germanium wafer. The lattice compatibility between the germanium wafer and the short-wave infrared sensing layer 410 including germanium is higher.

[0072] S105, forming a third bonding layer on one side of the short-wave infrared sensing layer.

[0073] In the embodiment of the present application, after the short-wave infrared sensing layer 410 is formed, a third bonding layer 430 may be formed on one side of the short-wave infrared sensing layer 410. Figure 7As shown, the bonding with the second acceptor substrate 300 is achieved by using the third bonding layer 430. The material of the third bonding layer 430 may be aluminum oxide. As an example, the thickness of the third bonding layer 430 may be 10 nm.

[0074] In practical applications, a fourth bonding layer 310 may also be formed on one side surface of the second acceptor substrate 300. Figure 8 As shown, the bonding difficulty is reduced and the bonding strength is improved. The material of the fourth bonding layer 310 can be aluminum oxide. As an example, the thickness of the fourth bonding layer 310 can be 10 nm.

[0075] S106 , bonding the second acceptor substrate and the second donor substrate with the third bonding layer facing the second acceptor substrate.

[0076] In the embodiment of the present application, the second acceptor substrate 300 and the second donor substrate 400 may be directly wafer-bonded. Specifically, the second acceptor substrate 300 and the second donor substrate 400 may be bonded in a direction where the third bonding layer 430 faces the second acceptor substrate 300 .

[0077] refer to Fig. 9 As shown, since the fourth bonding layer 310 is also formed on the second acceptor substrate 300, when the second acceptor substrate 300 and the second donor substrate 400 are bonded, the third bonding layer 430 is bonded toward the fourth bonding layer 310. After bonding, the third bonding layer 430 and the fourth bonding layer 310 are in direct contact.

[0078] S107, removing the second donor substrate to obtain a dual-band image sensor wafer.

[0079] In the embodiment of the present application, after the second acceptor substrate 300 and the second donor substrate 400 are bonded, the second donor substrate 400 and the buffer layer 420 can be removed to expose the short-wave infrared sensing layer 410, thereby forming a dual-band image sensor wafer 1000, referring to Figure 1 shown.

[0080] Specifically, the second donor substrate 400 and the buffer layer 420 may be removed by using a backside thinning process, a chemical mechanical polishing (CMP) process, a dry etching process, or a wet etching process.

[0081] In summary, the dual-band image sensor wafer of the embodiment of the present application uses silicon as the ultraviolet sensing layer, germanium as the short-wave infrared sensing layer, and uses a glass substrate or a sapphire substrate as the first acceptor substrate, which has the following advantages: the glass substrate or the sapphire substrate is a transparent substrate, which is highly transparent in both the ultraviolet band and the short-wave infrared band, and is beneficial to the formation of a back-illuminated ultraviolet-short-wave infrared dual-band image sensor. The transparent substrate has the characteristics of low absorption and low scattering in the ultraviolet band and the short-wave infrared band, ensuring that the ultraviolet-short-wave infrared dual-band image sensor has extremely high light collection efficiency, reducing signal loss and noise, and improving the sensitivity and accuracy of the image sensor. The use of silicon as the ultraviolet sensing layer is based on the fact that silicon wafers and silicon manufacturing processes are relatively mature, and the first acceptor substrate, the first bonding layer on the first acceptor substrate, the second bonding layer, and even the third bonding layer and the fourth bonding layer on the top of the ultra-thin silicon are all excellent insulators, forming a resonant cavity in the vertical direction, which is beneficial to improving the dark current, peak responsivity, quantum efficiency and operating speed of the ultra-thin silicon ultraviolet image sensor. Germanium as a short-wave infrared sensing layer has excellent photoelectric response in the short-wave infrared band, and the manufacturing process is compatible with Si CMOS process, can be silicon-based epitaxial, and has high carrier mobility. For the germanium short-wave infrared image sensor, the third bonding layer and the fourth bonding layer, the ultra-thin silicon layer, and the first bonding layer and the second bonding layer below the germanium also form a resonant cavity in the vertical direction, which is beneficial to improving the dark current, peak responsivity, quantum efficiency and operating speed of the germanium short-wave infrared image sensor. The manufacturing method of the dual-band image sensor wafer provided in the embodiment of the present application uses ultra-thin silicon and germanium that are highly compatible with the standard CMOS process as the sensing layer, and uses two direct wafer bonding processes to form ultra-thin silicon and germanium on a single transparent substrate, respectively. The ultra-thin silicon and germanium are spaced by the third bonding layer, which solves the lattice mismatch and thermal mismatch problems at the interface between germanium and silicon, and is beneficial to improving the dark current, peak responsivity, peak quantum efficiency and operating speed of the germanium short-wave infrared image sensor.

[0082] Based on the dual-band image sensor wafer provided in the above embodiment, the embodiment of the present application further provides a dual-band image sensor, and its working principle is described in detail below with reference to the accompanying drawings.

[0083] See also Fig.10 , which is a schematic diagram of the structure of a dual-band image sensor provided in an embodiment of the present application.

[0084] The dual-band image sensor provided in this embodiment includes a bonded dual-band imaging chip and a readout circuit wafer 2000 .

[0085] The dual-band imaging chip is manufactured using a dual-band image sensor wafer 1000 . The dual-band image sensor wafer 1000 includes a first acceptor substrate 200 , a first bonding layer 110 , an ultraviolet sensing layer 120 , a third bonding layer 430 and a short-wave infrared sensing layer 410 stacked in sequence.

[0086] The ultraviolet sensing layer 120 is a semiconductor material that absorbs ultraviolet waves, and the short-wave infrared sensing layer 410 is a semiconductor material that absorbs infrared waves. The material of the short-wave infrared sensing layer 410 at least includes germanium.

[0087] In actual applications, a second bonding layer 210 is also formed on the first acceptor substrate 200, and a fourth bonding layer 310 is also provided between the ultraviolet sensing layer 120 and the third bonding layer 430, that is, the dual-band image sensor wafer 1000 includes a first acceptor substrate 200, a second bonding layer 210, a first bonding layer 110, an ultraviolet sensing layer 120, a fourth bonding layer 310, a third bonding layer 430 and a short-wave infrared sensing layer 410 stacked in sequence.

[0088] The readout circuit wafer 2000 may include a circuit layer for reading the output signal of the dual-band image sensor wafer 1000 .

[0089] In the embodiment of the present application, the dual-band imaging chip includes an ultraviolet sensing region 1100 and a short-wave infrared sensing region 1200, that is, the dual-band image sensor wafer 1000 includes an ultraviolet sensing region 1100 and a short-wave infrared sensing region 1200. The ultraviolet sensing region 1100 includes a first opening 1300, and the first opening 1300 is obtained by etching the short-wave infrared sensing layer 410. The ultraviolet sensing layer 120 of the ultraviolet sensing region 1100 includes a first N-type region 121 and a first P-type region 122, and the short-wave infrared sensing layer 410 of the short-wave infrared sensing region 1200 includes a second N-type region 411 and a second P-type region 412. The first P-type region 122 and the second P-type region 412 are electrically connected by using a first electrode 1410, a first interconnect layer 1400, and a second electrode 1420. The first N-type region 121 and the second N-type region 411 are electrically connected by using a third electrode 1510, a second interconnect layer 1500, and a fourth electrode 1520. The first interconnect layer 1400 is electrically led out by using a P-type electrode 1600, and the second interconnect layer 1500 is electrically led out by using an N-type electrode 1700.

[0090] The readout circuit wafer 2000 is electrically connected to the P-type electrode 1600 and the N-type electrode 1700 respectively. When the electrical connection is performed, a bonding metal layer 1800 may be used for electrical connection. Fig.10 shown.

[0091] In practical applications, considering that the dual-band image sensor wafer 1000 can be used to manufacture multiple dual-band imaging chips, multiple dual-band imaging chips need to be isolated and protected, so a surface passivation layer 3100 is provided on the surface of the dual-band image sensor wafer 1000, and the surface passivation layer 3100 is provided between the short-wave infrared sensing layer 410 and the first interconnection layer 1400. The surface passivation layer 3100 covers the first opening 1300 and the short-wave infrared sensing layer 410, and is used to protect the short-wave infrared sensing layer 410. A shallow trench isolation structure 3200 is provided between the multiple dual-band imaging chips, and the shallow trench isolation structure 3200 at least penetrates the surface passivation layer 3100, the short-wave infrared sensing layer 410, the third bonding layer 430, the fourth bonding layer 310 and the ultraviolet sensing layer 120.

[0092] Based on the dual-band image sensor provided in the above embodiment, the embodiment of the present application further provides a method for manufacturing the dual-band image sensor, and its working principle is described in detail below with reference to the accompanying drawings.

[0093] See also Fig.11 , which is a schematic flow chart of a method for manufacturing a dual-band image sensor provided in an embodiment of the present application.

[0094] The manufacturing method of the dual-band image sensor provided in this embodiment includes the following steps:

[0095] S201, providing a dual-band image sensor wafer and a readout circuit wafer.

[0096] In the embodiment of the present application, the band image sensor wafer 1000 includes a first acceptor substrate 200 , a first bonding layer 110 , an ultraviolet sensing layer 120 , a third bonding layer 430 and a short-wave infrared sensing layer 410 which are stacked in sequence.

[0097] The ultraviolet sensing layer 120 is a semiconductor material that absorbs ultraviolet waves, and the short-wave infrared sensing layer 410 is a semiconductor material that absorbs infrared waves. The material of the short-wave infrared sensing layer 410 at least includes germanium.

[0098] In actual applications, a second bonding layer 210 is also formed on the first acceptor substrate 200, and a fourth bonding layer 310 is also provided between the ultraviolet sensing layer 120 and the third bonding layer 430, that is, the dual-band image sensor wafer 1000 includes a first acceptor substrate 200, a second bonding layer 210, a first bonding layer 110, an ultraviolet sensing layer 120, a fourth bonding layer 310, a third bonding layer 430 and a short-wave infrared sensing layer 410 stacked in sequence.

[0099] The readout circuit wafer 2000 may include a circuit layer for reading the output signal of the dual-band image sensor wafer 1000 .

[0100] In practical applications, considering that the dual-band image sensor wafer 1000 can be used to manufacture multiple dual-band imaging chips, multiple dual-band imaging chips need to be isolated and protected, so a surface passivation layer 3100 can be formed on the surface of the dual-band image sensor wafer 1000, and the surface passivation layer 3100 covers the short-wave infrared sensing layer 410 to protect the short-wave infrared sensing layer 410. A shallow trench isolation structure 3200 is formed between the multiple dual-band imaging chips, and the shallow trench isolation structure 3200 at least penetrates the surface passivation layer 3100, the short-wave infrared sensing layer 410, the third bonding layer 430, the fourth bonding layer 310 and the ultraviolet sensing layer 120. The material of the surface passivation layer 3100 can be silicon oxide.

[0101] S202, etching the short-wave infrared sensing layer to form a first opening.

[0102] In the embodiment of the present application, in order to form an ultraviolet sensor and a short-wave infrared sensor respectively, the short-wave infrared sensing layer 410 can be etched to form a first opening 1300. Specifically, the surface passivation layer 3100 and the short-wave infrared sensing layer 410 are etched to form the first opening 1300. The first opening 1300 penetrates the surface passivation layer 3100 and the short-wave infrared sensing layer 410. Fig.12 shown.

[0103] The area where the first opening 1300 is located is the ultraviolet sensing area 1100, and the area without the first opening 1300 is the shortwave infrared sensing area 1200. The ultraviolet sensing area 1100 can subsequently form an ultraviolet sensor, and the shortwave infrared sensing area 1200 can form a shortwave infrared sensor.

[0104] S203, forming a first N-type region and a first P-type region in the ultraviolet sensing layer in the ultraviolet sensing region, and forming a second N-type region and a second P-type region in the short-wave infrared sensing layer in the short-wave infrared sensing region.

[0105] In the embodiment of the present application, a first N-type region 121 and a first P-type region 122 may be formed in the ultraviolet sensing layer 120 of the ultraviolet sensing region 1100, and a second N-type region 411 and a second P-type region 412 may be formed in the short-wave infrared sensing layer 410 of the short-wave infrared sensing region 1200. Fig.13 shown.

[0106] Specifically, an ion implantation process may be used to form the first N-type region 121 and the first P-type region 122 in the ultraviolet sensing layer 120 , and to form the second N-type region 411 and the second P-type region 412 in the short-wave infrared sensing layer 410 .

[0107] After forming the first N-type region 121 and the first P-type region 122 in the ultraviolet sensing layer 120 by an ion implantation process, the first opening 1300 may be filled and planarized by a chemical mechanical polishing process, and then a second N-type region 411 and a second P-type region 412 may be formed in the short-wave infrared sensing layer 410 .

[0108] S204, forming a first electrode and a third electrode respectively penetrating the third bonding layer to the first P-type region and the first N-type region of the ultraviolet sensing layer, and forming a second electrode and a fourth electrode respectively directly contacting the second P-type region and the second N-type region of the short-wave infrared sensing layer.

[0109] In the embodiment of the present application, a first electrode 1410 , a second electrode 1420 , a third electrode 1510 and a fourth electrode 1520 may be formed respectively to electrically lead out the first P-type region 122 , the second P-type region 412 , the first N-type region 121 and the second N-type region 411 .

[0110] Specifically, the first electrode 1410 penetrates the third bonding layer 430 and the fourth bonding layer 310 to the first P-type region 122 of the ultraviolet sensing layer 120, and the third electrode 1510 penetrates the third bonding layer 430 and the fourth bonding layer 310 to the first N-type region 121 of the ultraviolet sensing layer 120. The second electrode 1420 penetrates the surface passivation layer 3100 to the second P-type region 412 of the short-wave infrared sensing layer 410, and the fourth electrode 1520 penetrates the surface passivation layer 3100 to the second N-type region 411 of the short-wave infrared sensing layer 410, with reference to Fig.14 shown.

[0111] In practical applications, the sequence of processes for forming the first electrode 1410 , the second electrode 1420 , the third electrode 1510 , and the fourth electrode 1520 may be determined according to actual conditions and is not limited to the situation described in the embodiment of the present application.

[0112] S205 , forming a first interconnect layer and a second interconnect layer.

[0113] In the embodiment of the present application, a first interconnection layer 1400 connecting the first electrode 1410 and the second electrode 1420 and a second interconnection layer 1500 connecting the third electrode 1510 and the fourth electrode 1520 may be formed respectively. Fig.15 shown.

[0114] Specifically, the first interconnect layer 1400 and the second interconnect layer 1500 are metal layers, which are used to realize electrical connection between the first electrode 1410 and the second electrode 1420 and electrical connection between the third electrode 1510 and the fourth electrode 1520. The first interconnect layer 1400 and the second interconnect layer 1500 are also surrounded by an insulating layer 1800, and the insulating layer 1800 is used to isolate the first interconnect layer 1400 and the second interconnect layer 1500.

[0115] S206, forming a P-type electrode and an N-type electrode.

[0116] In the embodiment of the present application, a P-type electrode 1600 and an N-type electrode 1700 may be formed, the first interconnection layer 1400 is electrically led out using the P-type electrode 1600, and the second interconnection layer 1500 is electrically led out using the N-type electrode 1700. Fig.16 shown.

[0117] Specifically, the P-type electrode 1600 and the N-type electrode 1700 may be surrounded by an insulating layer 1800 for isolation.

[0118] S207 , bonding the dual-band image sensor wafer and the readout circuit wafer with the P-type electrode and the N-type electrode facing the readout circuit wafer.

[0119] In the embodiment of the present application, the dual-band image sensor wafer 1000 and the readout circuit wafer 2000 may be bonded in a direction where the P-type electrode 1600 and the N-type electrode 1700 face the readout circuit wafer 2000 .

[0120] Specifically, the dual-band image sensor wafer 1000 and the readout circuit wafer 2000 are bump-bonded, so that the readout circuit wafer 2000 is electrically connected to the P-type electrode 1600 and the N-type electrode 1700 respectively. The readout circuit wafer 2000 is electrically connected to the P-type electrode 1600 and the N-type electrode 1700 respectively. When the electrical connection is specifically made, a bonding metal layer 1900 may be used for electrical connection. Fig.10 shown.

[0121] In practical applications, the ultraviolet light signal enters the ultraviolet sensing layer 120 of the ultraviolet sensing region 1100 through the first acceptor substrate 200, and the ultraviolet sensing layer 120 is used to realize the optical response of the ultraviolet light signal. Since the ultraviolet sensing region 1100 includes the first opening 1300, the ultraviolet light signal will not have signal loss in the ultraviolet sensing region 1100. The short-wave infrared light signal enters the short-wave infrared sensing layer 410 of the short-wave infrared sensing region 1200 through the first acceptor substrate 200, and the short-wave infrared sensing layer 410 is used to realize the optical response of the short-wave infrared light signal.

[0122] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the structural embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. Ordinary technicians in this field can understand and implement it without paying creative work.

[0123] The above is only a preferred implementation of the present application. Although the present application has been disclosed as a preferred embodiment, it is not intended to limit the present application. Any technician familiar with the art can use the above disclosed methods and technical contents to make many possible changes and modifications to the technical solution of the present application without departing from the scope of the technical solution of the present application, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application still falls within the scope of protection of the technical solution of the present application.

Claims

1. A dual-band image sensor wafer, characterized in that: It comprises a first acceptor substrate, a first bonding layer, an ultraviolet sensing layer, a third bonding layer and a short-wave infrared sensing layer which are stacked in sequence; The ultraviolet sensing layer is a semiconductor material that absorbs ultraviolet waves, and the short-wave infrared sensing layer is a semiconductor material that absorbs infrared waves; the material of the short-wave infrared sensing layer is germanium, germanium-tin, germanium-silicon or silicon-germanium-tin.

2. The dual-band image sensor wafer according to claim 1, characterized in that: The material of the ultraviolet sensing layer is silicon.

3. The dual-band image sensor wafer according to claim 1, characterized in that: The first acceptor substrate is a glass substrate or a sapphire substrate.

4. The dual-band image sensor wafer according to claim 1, characterized in that: The short-wave infrared sensing layer is an intrinsic layer, and the material of the intrinsic layer is germanium, germanium tin or silicon germanium tin.

5. The dual-band image sensor wafer according to claim 1, characterized in that: The short-wave infrared sensing layer is a stacked layer, which is formed by alternately stacking a first target layer and a second target layer. The first target layer is a germanium layer or a germanium-tin layer, and the second target layer is a germanium-silicon layer, a germanium-tin layer, or a silicon-germanium-tin layer.

6. The dual-band image sensor wafer according to claim 1, characterized in that: The thickness of the ultraviolet sensing layer is 20-30 nm.

7. The dual-band image sensor wafer according to claim 1, characterized in that: The thickness of the short-wave infrared sensing layer is 500-1000nm.

8. A dual-band image sensor, characterized in that: include: Bonded dual-band imaging chip and readout circuit wafer; The dual-band imaging chip is manufactured using a dual-band image sensor wafer, and the dual-band image sensor wafer includes a first acceptor substrate, a first bonding layer, an ultraviolet sensing layer, a third bonding layer, and a short-wave infrared sensing layer stacked in sequence; the ultraviolet sensing layer is a semiconductor material that absorbs the ultraviolet band, and the short-wave infrared sensing layer is a semiconductor material that absorbs the infrared band; the material of the short-wave infrared sensing layer is germanium, germanium-tin, germanium-silicon, or silicon-germanium-tin; The dual-band imaging chip comprises an ultraviolet sensing region and a short-wave infrared sensing region, the ultraviolet sensing region comprises a first opening, the first opening is obtained by etching the short-wave infrared sensing layer, the ultraviolet sensing layer of the ultraviolet sensing region comprises a first N-type region and a first P-type region, the short-wave infrared sensing layer of the short-wave infrared sensing region comprises a second N-type region and a second P-type region, the first P-type region and the second P-type region are electrically connected by a first electrode, a first interconnection layer and a second electrode, the first N-type region and the second N-type region are electrically connected by a third electrode, a second interconnection layer and a fourth electrode; the first interconnection layer is electrically led out by a P-type electrode, and the second interconnection layer is electrically led out by an N-type electrode; The readout circuit wafer is electrically connected to the P-type electrode and the N-type electrode respectively.

9. The dual-band image sensor according to claim 8, characterized in that: The dual-band image sensor further includes a surface passivation layer; The surface passivation layer is disposed between the short-wave infrared sensing layer and the first interconnection layer, and the surface passivation layer covers the first opening.

10. The dual-band image sensor according to claim 8, characterized in that: The material of the ultraviolet sensing layer is silicon; the first acceptor substrate is a glass substrate or a sapphire substrate.

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