Short-wave infrared image sensor and manufacturing method thereof

Abstract

The invention provides a short-wave infrared image sensor and a manufacturing method thereof. The method comprises the following steps: providing a wafer substrate of which a wafer comprises a first substrate, a buried oxide layer and a top germanium layer; doping the top germanium layer to form a first doping type germanium layer; etching the first doping type germanium layer to obtain a groove; forming an absorption layer in the groove; performing target thickness doping on the absorption layer of the target area to form a second doping type germanium layer, and enabling the absorption layer to surround the side wall and the bottom of the second doping type germanium layer; the absorption layer at least comprising germanium presents a concave structure which surrounds the second doping type germanium layer and is surrounded by the first doping type germanium layer in a direction perpendicular to the surface of the first substrate; the absorption layer of the concave structure can have high light absorption efficiency, high response speed, small dark current, high quantum efficiency and high signal-to-noise ratio. And the first metal layer and the second metal layer are formed, so that the high-performance short-wave infrared image sensor can be efficiently manufactured.

Description

Technical Field

[0001] The present invention relates to the field of semiconductors, and particularly to a short-wave infrared image sensor and a manufacturing method thereof. Background Art

[0002] With the development of semiconductor-related technologies, germanium (Ge) semiconductor materials that are highly compatible with complementary metal oxide semiconductor (CMOS) processes have outstanding advantages such as being able to be epitaxially grown on large-sized silicon (Si) substrates, having excellent light response in the short-wave infrared (SWIR) band, adjustable bandgap, and being adaptable to tensile strain engineering, alloy engineering, and doping engineering. They are considered important candidate sensing materials for the next-generation short-wave infrared imaging technology.

[0003] Currently, image sensors based on germanium materials already have mature manufacturing processes and corresponding excellent performance. However, there is still a need to further improve the performance of germanium-based image sensors. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a short-wave infrared image sensor and a manufacturing method thereof, which can achieve a high-performance germanium-based image sensor.

[0005] This application provides a manufacturing method of a short-wave infrared image sensor, and the method includes:

[0006] Providing a wafer substrate, the wafer substrate includes a first substrate, a buried oxide layer, and a top germanium layer that are sequentially stacked;

[0007] Doping the top germanium layer to form a first doped-type germanium layer;

[0008] Etching the first doped-type germanium layer to obtain a groove;

[0009] Forming an absorption layer in the groove, and the material of the absorption layer at least includes germanium;

[0010] Doping the absorption layer in the target area to a target thickness to form a second doped-type germanium layer, the first doped type is one of P-type doping and N-type doping, and the second doped type is the other of P-type doping and N-type doping; the absorption layer surrounds the sidewall and bottom of the second doped-type germanium layer;

[0011] Forming a first metal layer and a second metal layer, the first metal layer contacts the first doped-type layer, and the second metal layer contacts the second doped-type layer.

[0012] Optionally, the absorption layer penetrates through the first-doped-type germanium layer, and the absorption layer is in direct contact with the buried oxide layer.

[0013] Optionally, the absorption layer does not penetrate through the first-doped-type germanium layer, and the first-doped-type germanium layer surrounds the sidewall and bottom of the absorption layer.

[0014] Optionally, doping the top germanium layer to form the first-doped-type germanium layer includes:

[0015] Doping the top germanium layer by using an ion implantation process to form the first-doped-type germanium layer;

[0016] Doping the absorption layer in a target region to a target thickness to form the second-doped-type germanium layer includes:

[0017] Doping the absorption layer in the target region to the target thickness by using an ion implantation process to form the second-doped-type germanium layer; the target region is smaller than the region where the absorption layer is located, and the target thickness is smaller than the thickness of the absorption layer.

[0018] Optionally, forming the absorption layer in the groove includes:

[0019] Filling the groove with an absorption material by using a chemical vapor deposition process or in a molecular beam epitaxy process;

[0020] Removing the absorption material located outside the groove by using a chemical mechanical polishing process to form the absorption layer.

[0021] Optionally, the first substrate is a glass substrate, a sapphire substrate, or a silicon substrate.

[0022] Optionally, before forming the first metal layer and the second metal layer, the method further includes:

[0023] Forming a surface passivation layer that covers the first-doped-type germanium layer, the absorption layer, and the second-doped-type germanium layer;

[0024] Etching the surface passivation layer to form a first opening and a second opening, where the first opening exposes the first-doped-type germanium layer, and the second opening exposes the second-doped-type germanium layer;

[0025] Forming the first metal layer and the second metal layer includes:

[0026] Forming the first metal layer in the first opening and forming the second metal layer in the second opening.

[0027] Optionally, the method further includes:

[0028] Providing a readout circuit wafer that has a third metal layer and a fourth metal layer;

[0029] Bond the wafer substrate and the readout circuit wafer in a direction where the first metal layer and the second metal layer face the readout circuit wafer, with the third metal layer in contact with the first metal layer and the fourth metal layer in contact with the second metal layer.

[0030] Optionally, the method further includes:

[0031] Remove the first substrate.

[0032] This application provides a short-wave infrared image sensor, including: a bonded short-wave infrared image sensor wafer and a readout circuit wafer;

[0033] The short-wave infrared image sensor wafer includes a buried oxide layer and a first-doped germanium layer arranged in a stacked manner;

[0034] The first-doped germanium layer at least surrounds the sidewalls of the absorption layer, and the absorption layer surrounds the sidewalls and the bottom of the second-doped germanium layer; the material of the absorption layer at least includes germanium, the first doping type is one of P-type doping and N-type doping, and the second doping type is the other of P-type doping and N-type doping;

[0035] On the sides of the first-doped germanium layer and the second-doped germanium layer away from the first substrate, a first metal layer and a second metal layer are respectively provided, with the first metal layer in contact with the first-doped layer and the second metal layer in contact with the second-doped layer;

[0036] The short-wave infrared image sensor wafer is bonded to the readout circuit wafer using the first metal layer and the second metal layer, and the readout circuit wafer has a third metal layer and a fourth metal layer, with the third metal layer in contact with the first metal layer and the fourth metal layer in contact with the second metal layer.

[0037] The present application provides a method for manufacturing a short-wave infrared image sensor. The method includes: providing a wafer substrate, the wafer substrate including a first substrate, a buried oxide layer, and a top germanium layer stacked in sequence; doping the top germanium layer to form a first-doped germanium layer of a first doping type; etching the first-doped germanium layer of the first doping type to obtain a groove; forming an absorption layer in the groove, the material of the absorption layer including at least germanium; doping the absorption layer in a target region to a target thickness to form a second-doped germanium layer of a second doping type, the first doping type being one of P-type doping and N-type doping, and the second doping type being the other of P-type doping and N-type doping, the absorption layer surrounding the sidewall and bottom of the second-doped germanium layer, that is, the absorption layer including at least germanium presents a concave structure surrounding the second-doped germanium layer and surrounded by the first-doped germanium layer in a direction perpendicular to the surface of the first substrate. The absorption layer having a concave structure can have a high light absorption efficiency, a high response speed, a small dark current, a high quantum efficiency, and a high signal-to-noise ratio, thereby providing a film layer basis for realizing a high-performance short-wave infrared image sensor. Forming a first metal layer and a second metal layer, the first metal layer contacting the first-doped type layer, and the second metal layer contacting the second-doped type layer, thereby forming electrical leads of the short-wave infrared image sensor. Thus, the present application forms an absorption layer having a concave structure through a simple manufacturing process, thereby achieving efficient manufacturing to obtain a high-performance short-wave infrared image sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0039] Figure 1 FIG. shows a schematic flow chart of a method for manufacturing a short-wave infrared image sensor provided by an embodiment of the present application;

[0040] Figures 2 - 11 FIG. shows a schematic structural diagram of a short-wave infrared image sensor manufactured by the method for manufacturing a short-wave infrared image sensor provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] In order to enable those skilled in the art to better understand the solution of the present application, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0042] In the following description, numerous specific details are set forth to provide a thorough understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Those skilled in the art can make similar generalizations without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0043] The present application will be described in detail in conjunction with schematic diagrams. When detailing the embodiments of the present application, for ease of explanation, the cross-sectional views showing the device structure will be enlarged locally in a non-general proportion, and the schematic diagrams are only examples and should not limit the scope of protection of the present application herein. In addition, in actual production, three-dimensional spatial dimensions including length, width, and depth should be included.

[0044] Currently, image sensors based on germanium materials already have mature structures and manufacturing processes. Image sensors based on germanium materials include Germanium on Insulator (GOI) short-wave infrared image sensors, and GOI short-wave infrared image sensors are considered to be the most promising short-wave infrared image sensors for commercial use. The structure of a GOI short-wave infrared image sensor includes a passivation layer, a PIN structure based on germanium materials, a buried oxide layer, and a silicon substrate, which are stacked in sequence from top to bottom. Although the above structure can improve the light absorption efficiency and dark current and other performance of the GOI short-wave infrared image sensor, its effect on improving the response speed is limited, and it may even cause problems such as an extended response time.

[0045] That is to say, there is still a need to further improve the performance of current image sensors based on germanium materials.

[0046] Based on this, the present application provides a manufacturing method for a short-wave infrared image sensor. The method includes: providing a wafer substrate, the wafer substrate including a first substrate, a buried oxide layer, and a top germanium layer that are sequentially stacked; doping the top germanium layer to form a germanium layer of a first doping type; etching the germanium layer of the first doping type to obtain a groove; forming an absorption layer in the groove, the material of the absorption layer including at least germanium; doping the absorption layer in a target area to a target thickness to form a germanium layer of a second doping type, the first doping type being one of P-type doping and N-type doping, and the second doping type being the other of P-type doping and N-type doping. The absorption layer surrounds the sidewall and bottom of the germanium layer of the second doping type. That is to say, the absorption layer including at least germanium presents a concave structure surrounding the germanium layer of the second doping type and surrounded by the germanium layer of the first doping type in the direction perpendicular to the surface of the first substrate. The absorption layer with a concave structure can have a high light absorption efficiency, a high response speed, a small dark current, a high quantum efficiency, and a high signal-to-noise ratio, thereby providing a film layer basis for realizing a high-performance short-wave infrared image sensor. Form a first metal layer and a second metal layer. The first metal layer contacts the first doping type layer, and the second metal layer contacts the second doping type layer, thereby forming an electrical lead-out of the short-wave infrared image sensor. It can be seen that the present application forms an absorption layer with a concave structure through a simple manufacturing process, thereby achieving efficient manufacturing to obtain a high-performance short-wave infrared image sensor.

[0047] To better understand the technical solutions and technical effects of the present application, specific embodiments will be described in detail below with reference to the accompanying drawings.

[0048] See Figure 1 , which is a schematic flow chart of a manufacturing method for a short-wave infrared image sensor provided by an embodiment of the present application.

[0049] The manufacturing method for the short-wave infrared image sensor provided by this embodiment includes the following steps:

[0050] S101, providing a wafer substrate, the wafer substrate including a first substrate, a buried oxide layer, and a top germanium layer that are sequentially stacked.

[0051] In the embodiment of the present application, the already manufactured wafer substrate 100 can be directly used as the process basis to manufacture the short-wave infrared image sensor. The wafer substrate 100 includes a first substrate 110, a buried oxide layer 120, and a top germanium layer 130 that are sequentially stacked. Refer to Figure 2As shown. The first substrate 110 is the base of the wafer substrate 100. According to whether the first substrate 110 is light-transmissive, the first substrate 110 can be divided into a light-transmissive substrate and a light-opaque substrate. The light-transmissive substrate can be used to directly form a back-illuminated short-wave infrared image sensor later. When the light-opaque substrate is used to form a back-illuminated short-wave infrared image sensor later, it can be removed, so as to realize the light entering from the back of the short-wave infrared image sensor.

[0052] As a possible implementation, the first substrate 110 can be a glass substrate, a sapphire substrate or a silicon substrate. Both the glass substrate and the sapphire substrate are transparent substrates and can be directly used to form a back-illuminated short-wave infrared image sensor. The silicon substrate is an opaque substrate, and the silicon substrate can be directly removed when forming a back-illuminated short-wave infrared image sensor later.

[0053] The material of the buried oxide layer 120 is an oxide. For example, the material of the buried oxide layer 120 is silicon oxide. The material of the top germanium layer 130 is germanium. The thickness of the top germanium layer 130 is 1000 - 3000 nm. By setting a relatively thick top germanium layer 130, it is convenient to form a concave absorption layer later, and then form a PIN structure with a concave structure.

[0054] That is to say, according to the different materials of the first substrate 110, wafer substrates 100 with different bases are provided. When the first substrate 110 is a silicon substrate, the wafer substrate 100 is a Germanium on Insulator (GOI) wafer. When the first substrate 110 is a sapphire substrate, the wafer substrate 100 is a Germanium on Sapphire (GOS) wafer. When the first substrate 110 is a glass substrate, the wafer substrate 100 is a Germanium on Glass (GOG) wafer.

[0055] It can be seen that preparing a short-wave infrared image sensor using the provided wafer substrate 100 has many manufacturing process advantages. The wafer substrate 100 has high compatibility with the CMOS process, can utilize existing equipment and processes, reduce costs and shorten the development cycle. The germanium layer of the wafer substrate 100 has high quality and excellent light response in the short-wave infrared band, ensuring the stable and reliable performance of the short-wave infrared image sensor and reducing defects.

[0056] S102, doping the top germanium layer to form a germanium layer of the first doping type.

[0057] In the embodiment of the present application, the top germanium layer 130 can be doped to obtain a germanium layer 210 of the first doping type, as shown in Figure 3 As shown. The germanium layer 210 of the first doping type has conductivity after doping, can realize current transmission, and realize the electrical lead-out of the short-wave infrared image sensor.

[0058] When specifically doping the top germanium layer 130, doping of the first doping type or the second doping type can be performed, where the first doping type is one of P-type doping and N-type doping, and the second doping type is the other of P-type doping and N-type doping.

[0059] Specifically, an ion implantation process can be used to dope the top germanium layer 130 to obtain a germanium layer 210 of the first doping type.

[0060] In practical applications, the germanium layer 210 of the first doping type can be etched to the surface of the buried oxide layer 120 to form a plurality of openings, and the plurality of openings penetrate through the germanium layer 210 of the first doping type. An insulating material is filled in the plurality of openings to form shallow trench isolation 501, and a pixel region is between adjacent shallow trench isolations 501. The pixel region is used to set the light response film layer of the short-wave infrared image sensor.

[0061] S103, etching the germanium layer of the first doping type to obtain a groove.

[0062] In an embodiment of the present application, the germanium layer 210 of the first doping type is etched to obtain a plurality of grooves 502, as shown in the reference. Figure 4 Specifically, the germanium layer 210 of the first doping type located in each pixel region is etched so as to set a light response film layer in the pixel region, and one groove 502 can be etched in each pixel region.

[0063] As a possible implementation manner, the groove 502 does not penetrate through the germanium layer 210 of the first doping type, that is, the bottom of the groove 502 is a partial thickness of the germanium layer 210 of the first doping type.

[0064] As another possible implementation manner, the groove 502 penetrates through the germanium layer 210 of the first doping type, that is, the bottom of the groove 502 exposes the buried oxide layer 120.

[0065] The length of the groove 502 in the connection direction between adjacent shallow trench isolations 501 is less than the distance length between adjacent shallow trench isolations 501, which is convenient for setting a light response film layer with a suitable length when subsequently setting the light response film layer in the groove 502.

[0066] S104, forming an absorption layer in the groove, and the material of the absorption layer at least includes germanium.

[0067] In an embodiment of the present application, after the groove 502 is formed, an absorption layer 220 is formed in the groove 502, as shown in the reference. Figure 5 The material of the absorption layer 220 at least includes germanium. Germanium is a group-IV semiconductor material, has excellent optoelectronic response in the short-wave infrared band, is compatible with the CMOS process in the manufacturing process, can be epitaxially formed, and has a high carrier mobility.

[0068] Specifically, a chemical vapor deposition (CVD) process or a molecular beam epitaxy (MBE) process can be used to fill the absorbing material in the groove 502, and a chemical mechanical polishing process can be used to remove the absorbing material located outside the groove 502 to form the absorbing layer 220. The chemical mechanical polishing process can reduce the surface roughness of the absorbing layer 220, thereby improving the performance of the manufactured short-wave infrared image sensor.

[0069] As a possible implementation, when the groove 502 does not penetrate the first-doped type germanium layer 210, the absorbing layer 220 formed in the groove 502 also does not penetrate the first-doped type germanium layer 210, and the first-doped type germanium layer 210 surrounds the sidewalls and bottom of the absorbing layer 220. Since the bottom of the groove 502 is a partial thickness of the first-doped type germanium layer 210, the manufacturing process of forming the absorbing layer 220 including germanium on the first-doped type germanium layer 210 is easier.

[0070] As another possible implementation, the groove 502 penetrates the first-doped type germanium layer 210, and the absorbing layer 220 formed in the groove 502 also penetrates the first-doped type germanium layer 210, and the absorbing layer 220 is in direct contact with the buried oxide layer 120.

[0071] In the embodiments of the present application, the absorbing layer 220 may be composed of a single film layer or may be formed by stacking multiple film layers. That is to say, the absorbing layer 220 may be an intrinsic layer or a stacked layer, which will be specifically introduced below:

[0072] In some embodiments, the absorbing layer 220 may be an intrinsic layer, and the material of the intrinsic layer includes germanium and may also include other Group IV materials other than germanium. For example, the material of the intrinsic layer may be germanium, germanium tin (GeSn), or silicon germanium tin (SiGeSn).

[0073] In some embodiments, the absorbing layer 220 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 absorbing layer 220. 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.

[0074] As an example, the first target layer is a germanium layer and the second target layer is a germanium tin layer.

[0075] As another example, the first target layer is a germanium layer and the second target layer is a silicon germanium tin layer.

[0076] As yet another example, the first target layer is a germanium tin layer and the second target layer is a silicon germanium tin layer.

[0077] As yet another example, the first target layer is a germanium layer and the second target layer is a germanium silicon layer.

[0078] S105, doping the absorption layer of the target region to a target thickness to form a germanium layer of a second doping type, where the first doping type is one of P-type doping and N-type doping, and the second doping type is the other of P-type doping and N-type doping; the absorption layer surrounds the sidewalls and bottom of the germanium layer of the second doping type.

[0079] In an embodiment of the present application, after the absorption layer 220 is formed in the groove 502, the absorption layer 220 of the target region can be doped to a target thickness to form a germanium layer 230 of a second doping type, and the absorption layer 220 surrounds the sidewalls and bottom of the germanium layer 230 of the second doping type, as shown in the reference. Figure 6 as shown.

[0080] Specifically, the absorption layer 220 of the target region can be doped to a target thickness by using an ion implantation process to form a germanium layer 230 of a second doping type, where the target region is smaller than the region where the absorption layer 220 is located, and the target thickness is smaller than the thickness of the absorption layer 220, so as to realize that the germanium layer 230 of the second doping type is only formed in the target region and the target thickness of the absorption layer 220, and further form an absorption layer 220 with a concave structure in the direction perpendicular to the surface of the first substrate 110.

[0081] That is to say, the absorption layer 220 containing at least germanium presents a concave structure surrounding the germanium layer 230 of the second doping type and surrounded by the germanium layer 210 of the first doping type in the direction perpendicular to the surface of the first substrate 110. The absorption layer 220 with a concave structure can have a high light absorption efficiency, a high response speed, a small dark current, a high quantum efficiency, and a high signal-to-noise ratio, thus providing a film layer basis for realizing a high-performance short-wave infrared image sensor.

[0082] The absorption layer 220 can perform light absorption, so as to respond to light in the short-wave infrared band. The germanium layer 210 of the first doping type and the germanium layer 230 of the second doping type are doped germanium layers, which can be used as an electron transport layer or a hole transport layer to respond to charges. The first doping type is one of P-type doping and N-type doping, and the second doping type is the other of P-type doping and N-type doping, that is, the germanium layer 210 of the first doping type and the germanium layer 230 of the second doping type are of different doping types. By sequentially forming the germanium layer 210 of the first doping type, the absorption layer 220, and the germanium layer 230 of the second doping type, a PIN structure with a concave structure can be formed, which can be an important component for the subsequent short-wave infrared image sensor to work.

[0083] As an example, if the first doping type is P-type doping and the second doping type is N-type doping, then the germanium layer 210 of the first doping type is a P-type doped germanium layer, and the germanium layer 230 of the second doping type is an N-type doped germanium layer.

[0084] As another example, if the first doping type is N-type doping and the second doping type is P-type doping, then the germanium layer 210 of the first doping type is an N-type doped germanium layer, and the germanium layer 230 of the second doping type is a P-type doped germanium layer.

[0085] The absorption layer 220 having a concave structure in the direction perpendicular to the surface of the first substrate 110 can increase the propagation path length of light in the short-wave infrared image sensor, prompting the light to undergo multiple reflections and scattering, allowing the light to have more time to interact with the germanium material in the absorption layer 220 having a concave structure, and thus significantly improving the light absorption efficiency. In the absorption layer 220 having a concave structure, the electric field distribution is more reasonable because the concave structure can change the shape of the internal electric field, resulting in more efficient drift of the photo-generated carriers under the action of the electric field, prompting the photo-generated carriers to drift to the electrodes at a faster speed under the drive of the electric field, thereby reducing the transit time of the carriers and improving the response speed of the short-wave infrared image sensor. At the same time, since the capacitance is related to the area and spacing of the electrodes, the absorption layer 220 having a concave structure changes the effective spacing and area relationship between the electrodes, so it has a smaller junction capacitance, enabling the short-wave infrared image sensor to respond more quickly to light signals. Geometrically speaking, the concave structure can effectively increase the effective area of light absorption without increasing the planar size of the short-wave infrared image sensor, which is very crucial for improving the quantum efficiency of the short-wave infrared image sensor (i.e., the probability of incident photons generating photo-generated carriers), and can enable the short-wave infrared image sensor to generate sufficient photocurrent under weak light signals. Due to the improvement of the light absorption rate and the carrier collection efficiency, the short-wave infrared image sensor having the absorption layer 220 with a concave structure can significantly improve the quantum efficiency, especially perform well under low light conditions, and is suitable for precision detection in low light environments. The concave structure is beneficial to reducing the dark current in the short-wave infrared image sensor because it optimizes the electric field distribution and reduces the generation of carriers at defect states or interfaces. This indicates that the background noise of the short-wave infrared image sensor when not illuminated is lower, thereby improving the signal-to-noise ratio and the overall detection performance. At the same time, the PIN structure of the short-wave infrared image sensor is buried inside the structure of the short-wave infrared image sensor, and its contact area with the external environment is greatly reduced, which can effectively avoid the influence of surface states on the carrier generation process and can also effectively reduce the dark current of the short-wave infrared image sensor. In addition, the physical isolation between adjacent pixels is enhanced, reducing the diffusion path of carriers between pixels, making the surrounding electric field distribution more concentrated in the region of the current pixel, reducing the electric field influence on adjacent pixels, effectively reducing crosstalk, and improving the clarity and contrast of the image. It can be seen that the short-wave infrared image sensor having the absorption layer 220 with a concave structure can enhance the light absorption efficiency, accelerate the response speed, improve the quantum efficiency, reduce the dark current, and simplify the manufacturing process.

[0086] In practical applications, after forming the second-doped-type germanium layer 230, a surface passivation layer 1300 can be formed. The surface passivation layer 1300 covers the first-doped-type germanium layer 210, the absorption layer 220, and the second-doped-type germanium layer 230, as shown in the reference Figure 7 shown. The surface passivation layer 1300 can be etched to obtain a first opening 1400 and a second opening 1500. The first opening 1400 penetrates through the surface passivation layer 1300 to expose the first-doped-type germanium layer 210, and the second opening 1500 penetrates through the surface passivation layer 1300 to expose the second-doped-type germanium layer 230.

[0087] The surface passivation layer 1300 can be a multi-layer stacked negative capacitance material film layer or an oxide material film layer, and the surface passivation layer 1300 can also be a periodically stacked Bragg reflection film layer.

[0088] S106, form a first metal layer and a second metal layer. The first metal layer contacts the first-doped type layer, and the second metal layer contacts the second-doped type layer.

[0089] In the embodiments of the present application, to achieve the electrical lead-out of each pixel region, a first metal layer 1600 and a second metal layer 1700 can be formed, as shown in the reference Figure 8 shown. The first metal layer 1600 contacts the first-doped type layer 310, and the second metal layer 1700 contacts the second-doped type layer 320, so as to realize the signal transmission of the first-doped type layer 310 and the second-doped type layer 320 by using the first metal layer 1600 and the second metal layer 1700.

[0090] Specifically, the first metal layer 1600 and the second metal layer 1700 are respectively formed in the first opening 1400 and the second opening 1500. The first metal layer 1600 contacts the first-doped-type germanium layer 210, and the second metal layer 1700 contacts the second-doped-type germanium layer 230. That is, the first metal layer 1600 can perform electrical lead-out on the first-doped-type germanium layer 210, and the second metal layer 1700 can perform electrical lead-out on the second-doped-type germanium layer 230, as shown in the reference Figure 8 shown.

[0091] In practical applications, the process sequence of forming the first opening 1400 and the second opening 1500 can be determined according to the actual situation. Correspondingly, the process sequence of forming the first metal layer 1600 and the second metal layer 1700 can be determined according to the actual situation.

[0092] In an embodiment of the present application, to fabricate a short-wave infrared image sensor, a readout circuit wafer also needs to be provided to transmit electrical signals between the readout circuit wafer and the outside. The readout circuit wafer may include a circuit layer 2100 and a metal layer. The metal layer includes a third metal layer 2200 and a fourth metal layer 2300, and the circuit layer 2100 includes a signal readout circuit.

[0093] The wafer substrate 100 and the readout circuit wafer can be bonded with the first metal layer 1600 and the second metal layer 1700 facing the readout circuit wafer. Specifically, the wafer substrate 100 and the readout circuit wafer are subjected to bump bonding, so that the third metal layer 2200 contacts the first metal layer 1600, and the fourth metal layer 2300 contacts the second metal layer 1700, as shown in the reference Figure 10 shown.

[0094] In practical applications, part or all of the thickness of the first substrate 110 can also be removed, as shown in the reference Figure 11 shown, so that light can pass through the buried oxide layer 120 and the first-doped germanium layer 210 to reach the pixel 1200, achieving light response.

[0095] Based on the manufacturing method of a short-wave infrared image sensor provided in the above embodiments, an embodiment of the present application also provides a short-wave infrared image sensor. The working principle will be described in detail below with reference to the drawings.

[0096] See Figure 11 , which is a schematic structural diagram of a short-wave infrared image sensor provided in an embodiment of the present application.

[0097] The short-wave infrared image sensor provided in this embodiment includes a bonded short-wave infrared image sensor wafer and a readout circuit wafer.

[0098] The short-wave infrared image sensor wafer includes a buried oxide layer 120 and a first-doped germanium layer 210 arranged in a stacked manner.

[0099] The first-doped germanium layer 210 at least surrounds the sidewall of the absorption layer 220, and the absorption layer 220 surrounds the sidewall and bottom of the second-doped germanium layer 230; the material of the absorption layer 220 at least includes germanium, the first doping type is one of P-type doping and N-type doping, and the second doping type is the other of P-type doping and N-type doping.

[0100] On the sides of the first-doped germanium layer 210 and the second-doped germanium layer 230 away from the first substrate 110, a first metal layer 1600 and a second metal layer 1700 are respectively provided. The first metal layer 1600 contacts the first-doped germanium layer 210, and the second metal layer 1700 contacts the second-doped germanium layer 230.

[0101] The readout circuit wafer may include a circuit layer 2100 and a metal layer. Among them, the metal layer includes a third metal layer 2200 and a fourth metal layer 2300, and the circuit layer 2100 includes a signal readout circuit.

[0102] The short-wave infrared image sensor wafer is bonded to the readout circuit wafer using a first metal layer 1600 and a second metal layer 1700. The third metal layer 2200 is in contact with the first metal layer 1600, and the fourth metal layer 2300 is in contact with the second metal layer 1700.

[0103] Each embodiment in this specification is described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the structural embodiments, since they are basically similar to the method embodiments, the description is relatively simple. For the relevant parts, reference can be made to the description of the method embodiments. A person of ordinary skill in the art can understand and implement them without creative efforts.

[0104] The above are only the preferred embodiments of the present application. Although the present application has been disclosed above with preferred embodiments, it is not intended to limit the present application. Any person skilled in the art can make many possible changes and modifications to the technical solution of the present application, or modify it into an equivalent embodiment with equivalent changes, without departing from the scope of the technical solution of the present application. 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 fall within the scope of the protection of the technical solution of the present application.

Claims

1. A manufacturing method of a short-wave infrared image sensor, characterized in that, The method includes: Providing a wafer substrate, the wafer substrate including a first substrate, a buried oxide layer, and a top germanium layer stacked in sequence; Doping the top germanium layer to form a first doped germanium layer of a first doping type; Etching the first doped germanium layer of the first doping type to obtain a groove; Forming an absorption layer in the groove, the material of the absorption layer including at least germanium; Doping the absorption layer in a target region to a target thickness to form a second doped germanium layer of a second doping type, the first doping type being one of P-type doping and N-type doping, and the second doping type being the other of P-type doping and N-type doping; the absorption layer surrounds the sidewalls and bottom of the second doped germanium layer; Forming a first metal layer and a second metal layer, the first metal layer contacting the first doped type layer, and the second metal layer contacting the second doped type layer.

2. The method according to claim 1, wherein The absorption layer penetrates through the first doped germanium layer, and the absorption layer is in direct contact with the buried oxide layer.

3. The method according to claim 1, wherein The absorption layer does not penetrate through the first doped germanium layer, and the first doped germanium layer surrounds the sidewalls and bottom of the absorption layer.

4. The method according to claim 1, wherein The doping the top germanium layer to form a first doped germanium layer of a first doping type includes: Doping the top germanium layer using an ion implantation process to form a first doped germanium layer of a first doping type; The doping the absorption layer in a target region to a target thickness to form a second doped germanium layer of a second doping type includes: Doping the absorption layer in a target region to a target thickness using an ion implantation process to form a second doped germanium layer of a second doping type; the target region is smaller than the region where the absorption layer is located, and the target thickness is smaller than the thickness of the absorption layer.

5. The method according to claim 1, characterized in that, The forming the absorption layer in the groove includes: Filling the groove with an absorption material using a chemical vapor deposition process or a molecular beam epitaxy process; Removing the absorption material located outside the groove using a chemical mechanical polishing process to form an absorption layer.

6. The method according to claim 1, characterized in that, The first substrate is a glass substrate, a sapphire substrate, or a silicon substrate.

7. The method according to claim 1, wherein Before forming the first metal layer and the second metal layer, the method further includes: Forming a surface passivation layer that covers the first doped germanium layer, the absorption layer, and the second doped germanium layer; Etching the surface passivation layer to form a first opening and a second opening, the first opening exposing the first doped germanium layer, and the second opening exposing the second doped germanium layer; The forming the first metal layer and the second metal layer includes: Forming a first metal layer in the first opening and a second metal layer in the second opening.

8. The method according to claim 7, wherein The method further includes: Providing a readout circuit wafer having a third metal layer and a fourth metal layer; Bonding the wafer substrate and the readout circuit wafer with the first metal layer and the second metal layer facing the readout circuit wafer, the third metal layer contacting the first metal layer, and the fourth metal layer contacting the second metal layer.

9. The method according to claim 1, wherein The method further includes: Removing the first substrate.

10. A short-wave infrared image sensor, characterized in that, Includes: A bonded short-wave infrared image sensor wafer and a readout circuit wafer; The short-wave infrared image sensor wafer includes a buried oxide layer and a first doped germanium layer stacked. The first doped-type germanium layer at least surrounds the sidewalls of the absorption layer, and the absorption layer surrounds the sidewalls and the bottom of the second doped-type germanium layer; The material of the absorption layer at least includes germanium. The first doping type is one of P-type doping and N-type doping, and the second doping type is the other of P-type doping and N-type doping; A first metal layer and a second metal layer are respectively disposed on the sides of the first doped-type germanium layer and the second doped-type germanium layer away from the first substrate. The first metal layer is in contact with the first doped-type layer, and the second metal layer is in contact with the second doped-type layer; The short-wave infrared image sensor wafer is bonded to the readout circuit wafer by using the first metal layer and the second metal layer. The readout circuit wafer has a third metal layer and a fourth metal layer. The third metal layer is in contact with the first metal layer, and the fourth metal layer is in contact with the second metal layer.

Images