Short-wave infrared image sensor and manufacturing method thereof

Abstract

The invention provides a short wave infrared image sensor and a manufacturing method thereof, and the method comprises the steps: providing a wafer substrate which comprises a first substrate, a buried oxide layer and a top germanium layer, doping the top germanium layer to obtain a first doping type germanium layer; forming an absorption layer and a second doping type germanium layer on the first doping type germanium layer; a negative capacitance structure is formed on the second doping type germanium layer, the negative capacitance structure comprises a laminated structure or a single-layer structure, and the laminated structure is obtained by periodically or aperiodically laminating at least two different negative capacitance film layers in the direction perpendicular to the wafer substrate, the total capacitance of the short-wave infrared image sensor is reduced by using the negative capacitance structure at the top, the parasitic capacitance is reduced, and the equivalent electric field intensity is increased, so that the photoelectric conversion efficiency, the quantum efficiency, the sensitivity and the response speed of the short-wave infrared image sensor are improved, and the performance of the short-wave infrared image sensor is greatly enhanced. And rapid and efficient manufacturing of the image sensor is realized.

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 structures and manufacturing processes and have corresponding excellent performances. 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 the present 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] The present application provides a manufacturing method of a short-wave infrared image sensor, and the method includes:

[0006] Providing a wafer substrate, where the wafer substrate includes a first substrate, a buried oxide layer, and a top germanium layer stacked in sequence;

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

[0008] Forming an absorption layer and a second-doped-type germanium layer on the first-doped-type germanium layer, 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;

[0009] Forming a negative capacitance structure on the second-doped-type germanium layer, where the negative capacitance structure includes a stacked structure or a single-layer structure, and the stacked structure is obtained by stacking at least two different negative capacitance film layers periodically or non-periodically in a direction perpendicular to the wafer substrate;

[0010] Etching the negative capacitance structure, the second-doped-type germanium layer, the absorption layer, and a part of the thickness of the first-doped-type germanium layer to obtain a plurality of trenches, and the protrusions between adjacent trenches form pixels;

[0011] A first metal layer and a second metal layer are formed, the first metal layer is in contact with the first-doped-type germanium layer exposed by the trench, and the second metal layer penetrates through the negative capacitance structure and is in contact with the second-doped-type germanium layer.

[0012] Optionally, the single-layer structure is a negative capacitance film layer.

[0013] Optionally, the material of the negative capacitance film layer is PbZrTiO3, SrBi2Ta2O9, ferroelectric copolymer P(VDF-TrFE), or hafnium-based oxide.

[0014] Optionally, the thickness of the negative capacitance structure is 10 - 1000 nm.

[0015] Optionally, before forming the first metal layer and the second metal layer, the method further includes:

[0016] Forming a surface passivation layer that covers the first-doped-type germanium layer exposed by the trench, the sidewalls of the absorption layer exposed by the trench, the sidewalls of the second-doped-type germanium layer exposed by the trench, and the negative capacitance structure;

[0017] Etching the surface passivation layer and the negative capacitance structure to form a first opening and a second opening, the first opening exposing the first-doped-type germanium layer, and the second opening penetrating through the negative capacitance structure to expose the second-doped-type germanium layer;

[0018] The forming of the first metal layer and the second metal layer includes:

[0019] Forming a first metal layer in the first opening and a second metal layer in the second opening.

[0020] Optionally, the surface passivation layer is a negative capacitance film layer.

[0021] Optionally, the forming of the negative capacitance structure on the second-doped-type germanium layer includes:

[0022] Forming a negative capacitance structure on the second-doped-type germanium layer by atomic layer deposition.

[0023] Optionally, the first substrate is a glass substrate, a sapphire substrate, or a silicon substrate.

[0024] Optionally, the method further includes:

[0025] Providing a readout circuit wafer having a third metal layer and a fourth metal layer;

[0026] 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.

[0027] This application provides a short-wave infrared image sensor, comprising: a bonded short-wave infrared image sensor wafer and a readout circuit wafer;

[0028] The short-wave infrared image sensor wafer includes a buried oxide layer, a first doped germanium layer, an absorption layer, a second doped germanium layer, and a negative capacitance structure stacked in sequence. 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 negative capacitance structure includes a stacked structure or a single-layer structure. The stacked structure is obtained by periodically or non-periodically stacking at least two different negative capacitance film layers along a direction perpendicular to the wafer substrate.

[0029] The short-wave infrared image sensor wafer includes a plurality of pixels and a plurality of trenches. The trenches penetrate the negative capacitance structure, the second doped germanium layer, the absorption layer, and a part of the thickness of the first doped germanium layer. The pixels and the trenches are covered by a surface passivation layer. The surface passivation layer at the bottom of the trench has a first opening, in which there is a first metal layer in contact with the first doped germanium layer. The surface passivation layer at the top of the pixel and the negative capacitance structure have a second opening, in which there is a second metal layer that penetrates the negative capacitance structure and is in contact with the second doped germanium layer.

[0030] 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.

[0031] The present application provides a manufacturing method for a short-wave infrared image sensor. The method includes: providing a wafer substrate, which includes a first substrate, a buried oxide layer, and a top germanium layer stacked in sequence; doping the top germanium layer to obtain a germanium layer of a first doping type; forming an absorption layer and a germanium layer of a second doping type on the germanium layer of the first 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, that is, forming a PIN structure of the short-wave infrared image sensor to achieve light sensing performance; forming a negative capacitance structure on the germanium layer of the second doping type, that is, the negative capacitance structure is located at the top of the short-wave infrared image sensor, and the negative capacitance structure includes a stacked structure or a single-layer structure. The stacked structure is obtained by stacking at least two different negative capacitance film layers periodically or non-periodically along the direction perpendicular to the wafer substrate. The negative capacitance structure located at the top is used to reduce the total capacitance of the short-wave infrared image sensor, reduce the parasitic capacitance, increase the equivalent electric field strength, and thus improve the photoelectric conversion efficiency, quantum efficiency, sensitivity, and response speed of the short-wave infrared image sensor, greatly enhancing the performance of the short-wave infrared image sensor; etching the negative capacitance structure, the germanium layer of the second doping type, the absorption layer, and a part of the thickness of the germanium layer of the first doping type to obtain a plurality of trenches, and the protrusions between adjacent trenches form pixels; forming a first metal layer and a second metal layer, where the first metal layer contacts the germanium layer of the first doping type exposed by the trenches, and the second metal layer penetrates through the negative capacitance structure and contacts the germanium layer of the second doping type, that is, simultaneously forming a short-wave infrared image sensor including a plurality of pixels and performing electrical lead-out of the plurality of pixels, thereby realizing the rapid and efficient manufacturing of the image sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] 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 following drawings 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.

[0033] Figure 1 FIG. shows a flowchart of a manufacturing method for a short-wave infrared image sensor provided by an embodiment of the present application;

[0034] Figures 2 - 11 FIG. shows a structural diagram of a short-wave infrared image sensor manufactured by the manufacturing method for a short-wave infrared image sensor provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] To enable those skilled in the art to better understand the solution of this application, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the scope of protection of this application.

[0036] Many specific details are set forth in the following description to facilitate a thorough understanding of this application, but this application may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of this application. Therefore, this application is not limited by the specific embodiments disclosed below.

[0037] This application will be described in detail in conjunction with schematic diagrams. When detailing the embodiments of this application, for the convenience 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 this application herein. In addition, in actual production, three-dimensional spatial dimensions including length, width, and depth should be included.

[0038] 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 commercially available short-wave infrared image sensors. 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 stacked in sequence from top to bottom. The multi-layer structure of the GOI short-wave infrared image sensor is prone to light interference phenomena, that is, interference occurs between the reflected light and the incident light inside the GOI short-wave infrared image sensor, forming a resonant cavity effect, which can improve the light absorption efficiency and quantum efficiency of the GOI short-wave infrared image sensor to a certain extent, but has limited effect on improving the working speed of the GOI short-wave infrared image sensor, and may even cause problems such as extended response time.

[0039] That is to say, there is still a need to further improve the performance of current image sensors based on germanium materials.

[0040] Based on this, the present application provides a manufacturing method for a short-wave infrared image sensor, and the method includes: providing a wafer substrate, where the wafer substrate includes a first substrate, a buried oxide layer, and a top germanium layer stacked in sequence; doping the top germanium layer to obtain a germanium layer of a first doping type; forming an absorption layer and a germanium layer of a second doping type on the germanium layer of the first 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, that is, forming a PIN structure of the short-wave infrared image sensor to achieve light sensing performance; forming a negative capacitance structure on the germanium layer of the second doping type, that is, the negative capacitance structure is located at the top of the short-wave infrared image sensor, and the negative capacitance structure includes a stacked structure or a single-layer structure, and the stacked structure is obtained by stacking at least two different negative capacitance film layers periodically or aperiodically along the direction perpendicular to the wafer substrate, and the negative capacitance structure located at the top is used to reduce the total capacitance of the short-wave infrared image sensor, reduce the parasitic capacitance, increase the equivalent electric field strength, and further improve the photoelectric conversion efficiency, quantum efficiency, sensitivity, and response speed of the short-wave infrared image sensor, greatly enhancing the performance of the short-wave infrared image sensor; etching the negative capacitance structure, the germanium layer of the second doping type, the absorption layer, and a part of the thickness of the germanium layer of the first doping type to obtain a plurality of trenches, and the protrusions between adjacent trenches form pixels; forming a first metal layer and a second metal layer, where the first metal layer contacts the germanium layer of the first doping type exposed by the trenches, and the second metal layer penetrates through the negative capacitance structure and contacts the germanium layer of the second doping type, that is, simultaneously forming a short-wave infrared image sensor including a plurality of pixels and performing electrical lead-out of the plurality of pixels, thereby realizing the rapid and efficient manufacturing of the image sensor.

[0041] In order 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.

[0042] 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.

[0043] The manufacturing method for the short-wave infrared image sensor provided in this embodiment includes the following steps:

[0044] S101, providing a wafer substrate, where the wafer substrate includes a first substrate, a buried oxide layer, and a top germanium layer stacked in sequence.

[0045] In the embodiments of the present application, considering that there are many process steps for manufacturing a short-wave infrared image sensor, the present application can directly use the already manufactured wafer substrate 100 as the process basis to manufacture a short-wave infrared image sensor wafer, and then use the short-wave infrared image sensor wafer to manufacture a short-wave infrared image sensor, thereby omitting the process steps of additionally manufacturing the wafer substrate 100 by using the manufactured wafer substrate 100, such as omitting the preparation of the donor substrate and the acceptor substrate, the wafer bonding of the donor substrate and the acceptor substrate, and the back thinning and other cumbersome links, thus greatly simplifying the overall manufacturing process of the short-wave infrared image sensor.

[0046] The wafer substrate 100 includes a first substrate 110, a buried oxide layer 120, and a top germanium layer 130 that are sequentially stacked, as shown in Figure 2 the figure. 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 subsequently.

[0047] As a possible implementation, the first substrate 110 can be a glass substrate, a sapphire substrate, or a silicon substrate. The glass substrate and the sapphire substrate are both transparent substrates and can be directly used to form a back-illuminated short-wave infrared image sensor. The silicon substrate is a light-opaque substrate and can form a front-illuminated short-wave infrared image sensor.

[0048] 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 100 - 500 nm.

[0049] That is to say, according to the different materials of the first substrate 110, the wafer substrate 100 with different bases is 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.

[0050] It can be seen that using commercial GOI wafers, GOS wafers, and GOG wafers as starting materials significantly reduces the complex process steps required in the initial stage of wafer manufacturing for traditional short-wave infrared image sensor wafers and improves the manufacturing efficiency.

[0051] S102, doping the top germanium layer to obtain a first-doped type germanium layer.

[0052] In an embodiment of the present application, the top germanium layer 130 can be doped to obtain a germanium layer 210 of a first doping type, as shown in reference Figure 3 . After doping, the germanium layer 210 of the first doping type has conductivity, can achieve current transmission, and realizes the electrical lead-out of the short-wave infrared image sensor.

[0053] When specifically doping the top germanium layer 130, doping of the first doping type or doping of the second doping type can be carried out, 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.

[0054] Specifically, the ion implantation process can be used to dope the top germanium layer 130 to obtain the germanium layer 210 of the first doping type.

[0055] S103, forming an absorption layer and a germanium layer of the second doping type on the germanium layer of the first doping type.

[0056] In an embodiment of the present application, after doping the top germanium layer 130 to obtain the germanium layer 210 of the first doping type, continue to form an absorption layer 220 and a germanium layer 230 of the second doping type on the germanium layer 210 of the first doping type, as shown in reference Figure 4 .

[0057] Specifically, the molecular beam epitaxy (MBE) process or the chemical vapor deposition (CVD) process can be used to form the absorption layer 220 on the germanium layer 210 of the first doping type.

[0058] The absorption layer 220 can perform light absorption, so as to respond to light in the short-wave infrared band. The material of the absorption layer 220 is an intrinsic germanium material. 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 types of doping. 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, the core film layer of the subsequent short-wave infrared image sensor wafer is formed, which can be an important component for the subsequent short-wave infrared image sensor to work.

[0059] 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.

[0060] As another example, if the first doping type is N-type doping and the second doping type is P-type doping, then the first-doping-type germanium layer 210 is an N-type doped germanium layer, and the second-doping-type germanium layer 230 is a P-type doped germanium layer.

[0061] In practical applications, the thickness of the first-doping-type germanium layer 210 can be 100 - 500 nm, the thickness of the absorption layer 220 can be 500 - 3000 nm, and the thickness of the second-doping-type germanium layer 230 can be 100 - 500 nm.

[0062] In the embodiments of the present application, the absorption layer 220 can be composed of a single film layer or a stack of multiple film layers. That is to say, the absorption layer 220 can be an intrinsic layer or a stacked layer, which will be specifically introduced below:

[0063] In some embodiments, the absorption layer 220 can be an intrinsic layer. The material of the intrinsic layer includes germanium and can also include other group-IV materials except germanium. For example, the material of the intrinsic layer can be germanium, germanium tin (GeSn), or silicon germanium tin (SiGeSn).

[0064] In some embodiments, the absorption layer 220 can be a stacked layer, which 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 absorption 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.

[0065] As an example, the first target layer is a germanium layer and the second target layer is a germanium tin layer.

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

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

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

[0069] S104. Form a negative capacitance structure on the second-doping-type germanium layer. The negative capacitance structure includes a stacked structure or a single-layer structure. The stacked structure is obtained by periodically or non-periodically stacking at least two different negative capacitance film layers along a direction perpendicular to the wafer substrate.

[0070] In the embodiments of the present application, considering the performance improvement requirements of the short-wave infrared image sensor, especially the requirement for reducing the parasitic capacitance, a negative capacitance structure 300 can be formed on the second-doping-type germanium layer 230. Refer to Figure 5As shown, the use of the negative capacitance structure 300 reduces the total capacitance of the short-wave infrared image sensor, decreases the parasitic capacitance, increases the equivalent electric field strength, and thereby improves the photoelectric conversion efficiency, quantum efficiency, sensitivity, and response speed of the short-wave infrared image sensor, greatly enhancing the performance of the short-wave infrared image sensor.

[0071] The negative capacitance structure 300 includes a stacked structure or a single-layer structure. The stacked structure is obtained by periodically or aperiodically stacking at least two different negative capacitance film layers 310 in a direction perpendicular to the wafer substrate 100.

[0072] The negative capacitance film layer 310 is a film layer formed of a negative capacitance material, that is, the material of the negative capacitance film layer 310 is a negative capacitance material. The negative capacitance material has unique charge distribution characteristics in the spontaneous polarization state. When the negative capacitance film layer 310 is provided in the short-wave infrared image sensor, its negative capacitance effect can cancel part of the positive capacitance of the short-wave infrared image sensor, thereby reducing the total capacitance. Due to the reduction of the total capacitance of the short-wave infrared image sensor, the equivalent electric field strength inside the short-wave infrared image sensor increases. The enhanced electric field accelerates the separation of photo-generated carriers, shortens their residence time in the absorption layer 220, and reduces the occurrence probability of recombination. The accelerated carrier transport efficiency increases the photocurrent, enhances the photoelectric response, and thus improves the photoelectric conversion efficiency, quantum efficiency, and sensitivity of the short-wave infrared image sensor.

[0073] By providing the negative capacitance effect, the negative capacitance material can effectively reduce the total capacitance of the short-wave infrared image sensor. Correspondingly, the parasitic capacitance in the short-wave infrared image sensor decreases, improving the high-frequency response of the short-wave infrared image sensor. Especially in high-speed detection applications, the reduction of parasitic capacitance is beneficial to improving the signal transmission speed. That is to say, the negative capacitance effect reduces the parasitic capacitance, enabling the short-wave infrared image sensor to quickly respond to optical signals at a higher frequency. The reduction of parasitic capacitance can also improve the processing ability of the short-wave infrared image sensor for rapidly changing optical signals, thereby increasing the overall photoelectric response speed. Moreover, the reduction of parasitic capacitance helps to reduce signal delay, ensuring that photo-generated charges can be transmitted to the electrodes faster, and improving the output signal speed and accuracy of the short-wave infrared image sensor. At the same time, the negative capacitance effect can make the short-wave infrared image sensor respond more linearly to the input light intensity by generating a stronger electric field in the short-wave infrared image sensor, which is beneficial to achieving high-precision photoelectric signal detection. Especially in imaging and sensing applications that require high linearity, the negative capacitance material can effectively improve the output signal linearity of the short-wave infrared image sensor.

[0074] In addition, a negative capacitance structure 300 is integrated on the top of the short-wave infrared image sensor, enabling the deposition and processing of the negative capacitance structure 300 to be postponed until the later stage of the sensor manufacturing process, and also enabling the use of the wafer substrate as the starting material for the process flow, thereby reducing the complexity of the early processes. At the same time, the top-integrated negative capacitance structure 300 exhibits higher compatibility with other semiconductor processes such as lithography and etching, not only enhancing the manufacturing flexibility but also enhancing the customizability of the short-wave infrared image sensor.

[0075] That is to say, by forming the negative capacitance structure 300 on the second doped-type germanium layer 230, the negative capacitance structure 300 can be used to achieve advantages such as enhanced equivalent electric field, reduced parasitic effects, increased response speed, reduced signal delay, improved sensor linearity, and reduced manufacturing process difficulty of the short-wave infrared image sensor, thereby realizing the manufacture of a fast, efficient, and high-performance short-wave infrared image sensor.

[0076] In an embodiment of the present application, when the negative capacitance structure 300 is a stacked structure, the negative capacitance structure 300 is formed by overlapping at least two different negative capacitance film layers 310. When the optical signal is incident from the back of the short-wave infrared image sensor, the negative capacitance structure 300 formed by overlapping the multiple negative capacitance film layers 310 integrated on the top can directly reflect the incident light, prompting the light to undergo multiple reflections and absorptions within the absorption layer 220, thereby significantly enhancing the light absorption efficiency.

[0077] In an embodiment of the present application, the negative capacitance structure 300 can be a single-layer structure, and the single-layer structure is a layer of negative capacitance film layer 310, that is, the negative capacitance structure 300 can achieve performance improvement of the short-wave infrared image sensor by using only one layer of negative capacitance film layer 310.

[0078] In an embodiment of the present application, the negative capacitance structure 300 can be formed on the second doped-type germanium layer 230 by using the atomic layer deposition process.

[0079] In an embodiment of the present application, the thickness of the negative capacitance structure 300 is 10 - 1000 nm. That is to say, regardless of whether the negative capacitance structure 300 is a single-layer structure or a stacked structure, the performance of the short-wave infrared image sensor can be controlled by controlling the thickness of the negative capacitance structure 300.

[0080] In an embodiment of the present application, the material of the negative capacitance film layer 310 may be PbZrTiO3, SrBi2Ta2O9, ferroelectric copolymer P(VDF-TrFE), or hafnium-based oxide. When the negative capacitance structure 300 is a stacked structure and the stacked structure is a periodic structure, the negative capacitance structure 300 may be obtained by periodically overlapping at least 2 different negative capacitance film layers 310. For example, the negative capacitance structure 300 may be obtained by periodically overlapping negative capacitance film layers 310 with materials of PbZrTiO3 and SrBi2Ta2O9 respectively. When the negative capacitance structure 300 is a stacked structure and the stacked structure is an aperiodic structure, the negative capacitance structure 300 may be obtained by non-periodically overlapping at least 2 different negative capacitance film layers 310. For example, the negative capacitance structure 300 is obtained by overlapping 3 negative capacitance film layers 310, and the materials of the 3 negative capacitance film layers 310 are PbZrTiO3, SrBi2Ta2O9, and hafnium-based oxide respectively.

[0081] S105, etch the negative capacitance structure, the second-doped type germanium layer, the absorption layer, and a part of the thickness of the first-doped type germanium layer to obtain a plurality of trenches, and the protrusions between adjacent trenches form pixels.

[0082] In an embodiment of the present application, the negative capacitance structure 300, the second-doped type germanium layer 230, the absorption layer 220, and a part of the thickness of the first-doped type germanium layer 210 may be etched to obtain a plurality of trenches 1100. Specifically, the trenches 1100 penetrate through the negative capacitance structure 300, the second-doped type germanium layer 230, and the absorption layer 220, and do not penetrate through the first-doped type germanium layer 210. Refer to Figure 6 as shown.

[0083] There is a protrusion between adjacent trenches 1100, and the protrusion forms a pixel 1200. The pixel 1200 is the light-responsive part of the short-wave infrared image sensor.

[0084] S106, form a first metal layer and a second metal layer.

[0085] In an embodiment of the present application, to realize the electrical lead-out of each pixel 1200, a first metal layer 1600 and a second metal layer 1700 may be formed. The first metal layer 1600 is in contact with the first-doped type germanium layer 210 exposed by the trenches 1100, and the second metal layer 1700 penetrates through the negative capacitance structure 300 and is in contact with the second-doped type germanium layer 230, so as to realize the signal transmission of the first-doped type germanium layer 210 and the second-doped type germanium layer 230 by using the first metal layer 1600 and the second metal layer 1700.

[0086] Specifically, before forming the first metal layer 1600 and the second metal layer 1700, a surface passivation layer 1300 can be formed. The surface passivation layer 1300 covers the surfaces of the trench 1100 and the pixel 1200. Refer to Figure 7 As shown, it specifically covers the sidewalls and the bottom of the trench 1100 and the top of the pixel 1200, that is, the surface passivation layer 1300 covers the sidewalls of the first-doped-type germanium layer 210 exposed by the trench 1100, the sidewalls of the absorption layer 220 exposed by the trench 1100, the sidewalls of the second-doped-type germanium layer 230 exposed by the trench 1100, and the negative capacitance structure 300. Among them, the bottom of the trench 1100 is determined in the direction of the second-doped-type germanium layer 230 facing the first substrate 110, and the top of the pixel 1200 is also determined in the direction of the second-doped-type germanium layer 230 facing the first substrate 110.

[0087] As a possible implementation, the surface passivation layer 1300 can also be a negative capacitance film layer 310, that is, the surface passivation layer 1300 can also be a negative capacitance material, so as to further improve the performance of the manufactured short-wave infrared image sensor by using the negative capacitance material.

[0088] The surface passivation layer 1300 at the bottom of the trench 1100, the surface passivation layer 1300 at the top of the pixel 1200, and the negative capacitance structure 300 can be etched respectively to obtain a first opening 1400 and a second opening 1500. Refer to Figure 8 As shown, 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 and the negative capacitance structure 300 to expose the second-doped-type germanium layer 230.

[0089] Then, the first metal layer 1600 and the second metal layer 1700 are formed in the first opening 1400 and the second opening 1500 respectively. The first metal layer 1600 is in contact with the first-doped-type germanium layer 210, and the second metal layer 1700 is in contact with the second-doped-type germanium layer 230. That is, the first metal layer 1600 can electrically lead out the first-doped-type germanium layer 210, and the second metal layer 1600 can electrically lead out the second-doped-type germanium layer 230. Refer to Figure 9 As shown.

[0090] 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 also be determined according to the actual situation, not limited to the situation described in the embodiments of the present application.

[0091] 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 to and from the outside world using the readout circuit wafer. 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.

[0092] 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 figure.

[0093] 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 figure, so that light can pass through the buried oxide layer 120 and the first-doped germanium layer 210 to reach the pixel 1200, achieving a light response.

[0094] Based on the manufacturing method of a short-wave infrared image sensor provided in the above embodiments, the present application also provides a short-wave infrared image sensor. The working principle thereof will be described in detail below with reference to the accompanying drawings.

[0095] See Figure 11 , which is a schematic structural diagram of a short-wave infrared image sensor provided in an embodiment of the present application.

[0096] The short-wave infrared image sensor provided in this embodiment includes a bonded short-wave infrared image sensor wafer and a readout circuit wafer.

[0097] The short-wave infrared image sensor wafer includes a buried oxide layer 120, a first-doped germanium layer 210, an absorption layer 220, a second-doped germanium layer 230, and a negative capacitance structure 300 stacked in sequence. 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 negative capacitance structure 300 includes a stacked structure or a single-layer structure. The stacked structure is obtained by stacking at least two different negative capacitance film layers 310 periodically or non-periodically along a direction perpendicular to the wafer substrate 100.

[0098] As another possible implementation, the negative capacitance structure 300 includes a single-layer structure, and the single-layer structure is a layer of negative capacitance film layer 310.

[0099] 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. The circuit layer 2100 includes a signal readout circuit.

[0100] In an embodiment of the present application, the short-wave infrared image sensor wafer includes a plurality of pixels 1200 and a plurality of trenches 1100. The trenches 1100 penetrate through the negative capacitance structure 300, the second-doped type germanium layer 230, the absorption layer 220, and a part of the thickness of the first-doped type germanium layer 210. The pixels 1200 and the trenches 1100 are covered by a surface passivation layer 1300. The surface passivation layer 1300 at the bottom of the trench 1100 has a first opening 1400. A first metal layer 1600 is disposed in the first opening 1400. The first metal layer 1600 is in contact with the first-doped type germanium layer 210. The surface passivation layer 1300 at the top of the pixel 1200 and the negative capacitance structure 300 have a second opening 1500. A second metal layer 1700 is disposed in the second opening 1500. The second metal layer 1700 penetrates through the negative capacitance structure 300 and is in contact with the second-doped type germanium layer 230. The third metal layer 2200 is in contact with the first metal layer 1600. The fourth metal layer 2300 is in contact with the second metal layer 1700.

[0101] 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.

[0102] 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 obtain a germanium layer of a first doping type; forming an absorption layer and a germanium layer of a second doping type on the germanium layer of the first 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; forming a negative capacitance structure on the germanium layer of the second doping type, the negative capacitance structure including a stacked structure or a single-layer structure, the stacked structure being obtained by stacking at least two different negative capacitance film layers periodically or non-periodically along a direction perpendicular to the wafer substrate; etching the negative capacitance structure, the germanium layer of the second doping type, the absorption layer, and a partial thickness of the germanium layer of the first doping type to obtain a plurality of trenches, and the protrusions between adjacent trenches form pixels; forming a first metal layer and a second metal layer, the first metal layer being in contact with the germanium layer of the first doping type exposed by the trench, and the second metal layer passing through the negative capacitance structure and being in contact with the germanium layer of the second doping type.

2. The method according to claim 1, characterized in that, The single-layer structure is a layer of negative capacitance film layer.

3. The method according to claim 1, wherein The material of the negative capacitance film layer is PbZrTiO3, SrBi2Ta2O9, ferroelectric copolymer P(VDF-TrFE), or hafnium-based oxide.

4. The method according to claim 1, wherein The thickness of the negative capacitance structure is 10 - 1000 nm.

5. 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, the surface passivation layer covering the germanium layer of the first doping type exposed by the trench, the sidewalls of the absorption layer exposed by the trench, the sidewalls of the germanium layer of the second doping type exposed by the trench, and the negative capacitance structure; etching the surface passivation layer and the negative capacitance structure to form a first opening and a second opening, the first opening exposing the germanium layer of the first doping type, and the second opening passing through the negative capacitance structure to expose the germanium layer of the second doping type; The forming of 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.

6. The method according to claim 5, wherein The surface passivation layer is a negative capacitance film layer.

7. The method according to claim 1, wherein The forming of the negative capacitance structure on the germanium layer of the second doping type includes: forming a negative capacitance structure on the germanium layer of the second doping type by atomic layer deposition.

8. The method according to claim 1, wherein The first substrate is a glass substrate, a sapphire substrate, or a silicon substrate.

9. The method according to any one of claims 1 to 8, characterized in that, The method further includes: providing a readout circuit wafer, the 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 being in contact with the first metal layer, and the fourth metal layer being in contact with the second metal layer.

10. A short-wave infrared image sensor, characterized in that, including: a bonded short-wave infrared image sensor wafer and readout circuit wafer; The short-wave infrared image sensor wafer includes a buried oxide layer, a first doped germanium layer of a first doping type, an absorption layer, a second doped germanium layer of a second doping type, and a negative capacitance structure stacked in sequence. 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 negative capacitance structure includes a stacked structure or a single-layer structure. The stacked structure is obtained by stacking at least two different negative capacitance film layers periodically or non-periodically along a direction perpendicular to the wafer substrate. The short-wave infrared image sensor wafer includes a plurality of pixels and a plurality of trenches. The trenches penetrate the negative capacitance structure, the second doped germanium layer, the absorption layer, and a part of the thickness of the first doped germanium layer. The pixels and the trenches are covered by a surface passivation layer. The surface passivation layer at the bottom of the trench has a first opening, and a first metal layer is disposed in the first opening. The first metal layer is in contact with the first doped germanium layer. The surface passivation layer at the top of the pixel and the negative capacitance structure have a second opening, and a second metal layer is disposed in the second opening. The second metal layer penetrates the negative capacitance structure and is in contact with the second doped germanium 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.

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