Manufacturing method of semiconductor structure, semiconductor structure and image sensor

Abstract

The invention provides a manufacturing method of a semiconductor structure, the semiconductor structure and an image sensor. The manufacturing method of the semiconductor structure comprises the following steps: providing a substrate; wherein the base comprises a substrate and a sacrificial structure protruding out of the surface of the substrate; forming an isolation material layer covering the surface of the sacrificial structure and the surface of the substrate; removing the isolation material layer covering the surface, away from the substrate, of the sacrificial structure and covering part of the surface of the substrate, and reserving the isolation material layer covering the side surface of the sacrificial structure; removing the sacrificial structure to form at least two isolation structures protruding out of the surface of the substrate; and forming a photoelectric sensing structure between the adjacent isolation structures to obtain the semiconductor structure. According to the embodiment of the invention, gaps which are not filled in the isolation structure are reduced, the integrity of the isolation structure is improved, and the isolation effect of the isolation structure is improved.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, specifically to a method for manufacturing a semiconductor structure, a semiconductor structure, and an image sensor. Background Technology

[0002] With the continuous development of Complementary Metal Oxide Semiconductor Image Sensor (CIS) technology, back-illuminated image sensors are widely used in high-end optical imaging fields due to their higher quantum efficiency and superior imaging performance. Specifically, in a back-illuminated image sensor, light enters the sensor from the back side of the device where there are no conductive lines, thereby reducing the obstruction of light by the conductive lines. Especially under conditions of short light wavelength and low light intensity, back-illuminated image sensors have advantages such as strong photon capture capability and high imaging sensitivity.

[0003] To improve imaging quality and device integration, deep trench isolation (DTI) structures are typically used in the manufacturing process of existing back-illuminated image sensors to suppress the lateral diffusion of photons and electrons between adjacent pixels.

[0004] However, the deep trench isolation structure manufactured with existing technology has voids or gaps that are not filled with isolation material, which reduces the isolation effect of the deep trench isolation structure. Summary of the Invention

[0005] In view of this, several embodiments of this application provide a method for manufacturing a semiconductor structure, a semiconductor structure, and an image sensor to improve the isolation effect of deep trench isolation structures.

[0006] In one aspect, this application provides a method for manufacturing a semiconductor structure, the method comprising: providing a substrate; wherein the substrate includes a substrate and a sacrificial structure protruding from the surface of the substrate; forming an isolation material layer covering the surface of the sacrificial structure and the surface of the substrate; removing the isolation material layer covering the surface of the sacrificial structure away from the substrate and covering a portion of the surface of the substrate, while retaining the isolation material layer covering the side surface of the sacrificial structure; removing the sacrificial structure to form at least two isolation structures protruding from the surface of the substrate; and forming a photosensitive structure between adjacent isolation structures to obtain the semiconductor structure.

[0007] Optionally, the photoelectric sensing structure includes at least two photoelectric sensing material layers; within the photoelectric sensing structure, the doping elements in the at least two photoelectric sensing material layers are elements from the same main group; and the doping elements in adjacent photoelectric sensing material layers are different.

[0008] Optionally, the relative atomic mass of the ions doped in the at least two photosensitive material layers gradually decreases along the direction away from the substrate.

[0009] Optionally, forming a photoelectric sensing structure between adjacent isolation structures includes: using an epitaxial growth process to grow at least two photoelectric sensing material layers in segments between adjacent isolation structures.

[0010] Optionally, the step of forming an isolation material layer covering the surface of the sacrificial structure and the surface of the substrate includes: sequentially depositing a transition buffer layer, a transition conductive layer, and a transition isolation layer on the surface of the sacrificial structure and the surface of the substrate; wherein the material of the transition buffer layer and the material of the transition isolation layer are the same; the material of the transition conductive layer is different from the material of the transition buffer layer and the material of the transition isolation layer; removing portions of the transition isolation layer located on the side of the sacrificial structure away from the substrate and on the side of the transition conductive layer away from the substrate; depositing the material of the transition conductive layer on the side of the transition conductive layer away from the sacrificial structure and on the side of the transition conductive layer away from the substrate, forming a deposited conductive layer based on the transition conductive layer; wherein the deposited conductive layer surrounds the removed portion of the transition isolation layer; removing portions of the deposited conductive layer located on the side of the sacrificial structure away from the substrate and on the side of the transition buffer layer away from the substrate; depositing the material of the transition buffer layer on the side of the transition buffer layer away from the sacrificial structure and on the side of the transition buffer layer away from the substrate, forming a deposited buffer layer based on the transition buffer layer, thereby obtaining the isolation material layer; wherein the deposited buffer layer surrounds the removed portion of the deposited conductive layer.

[0011] Optionally, after the step of forming a photosensitive structure between adjacent isolation structures, the method of manufacturing the semiconductor structure further includes: depositing a conductive material on the side of the isolation structure and the photosensitive structure away from the substrate to form a connecting conductive layer; wherein the deposited conductive material is the same as the material of the deposited conductive layer; the remaining portion of the deposited conductive layer and the connecting conductive layer constitute a conductive structure.

[0012] Optionally, the sacrificial structure is made of carbon; removing the sacrificial structure includes: removing the sacrificial structure using an automated stripping process.

[0013] Optionally, the step of providing a substrate includes: providing a transition substrate; wherein the transition substrate includes the substrate, a sacrificial layer formed on the surface of the substrate, and a photolithographic functional layer formed on the side of the sacrificial layer away from the substrate; etching the sacrificial layer based on the photolithographic functional layer to form the sacrificial structure, thereby obtaining the substrate.

[0014] In another aspect, this application provides a semiconductor structure manufactured by the semiconductor structure manufacturing method described in the above embodiments.

[0015] In another aspect, this application provides an image sensor comprising a semiconductor structure manufactured by the semiconductor structure manufacturing method described in the above embodiments, or the image sensor comprising a semiconductor structure described in the above embodiments.

[0016] In several embodiments provided in this application, by forming an isolation material layer on the surface of the sacrificial structure covering the surface of the substrate and the substrate surface, removing the isolation material layer on the surface of the sacrificial structure away from the substrate and part of the substrate surface while retaining the isolation material layer on the side of the sacrificial structure, and then removing the sacrificial structure to form at least two isolation structures protruding from the substrate surface, and forming a photoelectric sensing structure between adjacent isolation structures, the unexpected effects achieved include: by covering the surface of the sacrificial structure protruding from the substrate surface and the substrate surface with an isolation material layer, then removing part of the isolation material layer, and retaining the isolation material layer on the side of the sacrificial structure as an isolation structure, the isolation structure is manufactured using a manufacturing process similar to that of a gate sidewall, which reduces the unfilled voids inside the isolation structure, improves the integrity of the isolation structure, and enhances the isolation effect of the isolation structure. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in describing the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram illustrating the formation of a barrier layer and a photoresist layer on a silicon wafer, provided for related technologies.

[0019] Figure 2 This is a schematic diagram illustrating the etching process to form isolation trenches on a silicon wafer, provided for related technologies.

[0020] Figure 3 A schematic diagram illustrating the formation of a deep trench isolation structure within an isolation trench, provided for related technologies.

[0021] Figure 4 Scanning electron microscope image of a deep trench isolation structure provided for related technologies.

[0022] Figure 5 A schematic flowchart illustrating the manufacturing method of the semiconductor structure provided in this application.

[0023] Figure 6 A schematic diagram of the structure of the transition substrate provided in this application.

[0024] Figure 7 A schematic diagram of the structure of the substrate provided in this application.

[0025] Figure 8 This is a schematic diagram showing the sequential deposition of a transition buffer layer, a transition conductive layer, and a transition isolation layer on the surface of the sacrificial structure and the substrate, as provided in this application.

[0026] Figure 9 This is a schematic diagram showing the removal of a portion of the transition isolation layer provided in this application.

[0027] Figure 10 This is a schematic diagram of the formation of the deposited conductive layer provided in this application.

[0028] Figure 11 This is a schematic diagram of the removal of a portion of the deposited conductive layer provided in this application.

[0029] Figure 12 This is a schematic diagram of the formation of the isolation material layer provided in this application.

[0030] Figure 13 This is a schematic diagram showing the removal of a portion of the isolation material layer provided in this application.

[0031] Figure 14 A schematic diagram of the removal of the sacrificial structure provided in this application.

[0032] Figure 15 This is a schematic diagram of the photoelectric sensing structure provided in this application.

[0033] Figure 16 This is a schematic diagram of the conductive structure provided in this application.

[0034] Structural designation explanation 110. Silicon wafer; 111. Isolation trench; 120. Barrier layer; 130. Photoresist layer; 140. Deep trench isolation structure; 141. First oxide layer; 142. High dielectric constant material layer; 143. Second oxide layer; 144. Void; 200. Transition substrate; 210. Substrate; 220. Sacrificial layer; 221. Sacrificial structure; 230. Photolithography functional layer; 231. Protective layer; 232. Photoresist layer; 240. Isolation material layer; 241. Deposition buffer layer; 241a. Deposition buffer layer; 241b. Deposition buffer layer 242. Residual portion removed; 242a. Transition conductive layer; 242b. Deposited conductive layer; 243. Residual portion removed from deposited conductive layer; 244a. Transition isolation layer; 243a. First residual portion removed from transition isolation layer; 243b. Second residual portion removed from transition isolation layer; 250. Isolation structure; 260. Photoelectric sensing structure; 261. First photoelectric sensing material layer; 262. Second photoelectric sensing material layer; 263. Third photoelectric sensing material layer; 270. Connecting conductive layer; 280. Dielectric layer; 290. Conductive structure; 300. Substrate. Detailed Implementation

[0035] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0036] The accompanying drawings provided in this application are only schematic illustrations of the basic concept of this application. The drawings only show the components related to this application and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the shape, quantity and proportion of each component may be changed, and the layout of the components may also be more complex.

[0037] In the description of the embodiments of this application, it should be understood that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," "center," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" and "second" may explicitly or implicitly include one or more of the stated features.

[0038] Please see Figures 1 to 3In related technologies, a process of etching followed by filling is typically used to form a deep trench isolation structure 140 within a silicon wafer 110. Specifically, a barrier layer 120 and a photoresist layer 130 can be formed on the silicon wafer 110 first. Then, using the photoresist layer 130 as an etching mask, dry etching is performed on the silicon wafer 110 to form spaced-apart isolation trenches 111 within the silicon wafer 110. Subsequently, a decoupling plasma oxidation (DPO) process is used to fill the isolation trenches 111 with oxide, forming a first oxide layer 141. The first oxide layer 141 can be used to reduce the direct contact between the high-dielectric-constant material subsequently filled into the isolation trenches 111 and the silicon wafer 110, thereby reducing stress concentration or lattice defects caused by interface mismatch between the silicon wafer 110 and the high-dielectric-constant material, and improving the difference in thermal expansion coefficients between the high-dielectric-constant material and the silicon wafer 110, thus improving the long-term reliability of the image sensor. After the first oxide layer 141 is formed, a conductive high-dielectric-constant material layer 142 can be formed on the surface of the first oxide layer 141. This high-dielectric-constant material layer 142 can then guide leakage current generated by illumination or bias voltage to the ground terminal, thereby reducing crosstalk between pixels. Finally, an atomic layer deposition (ALD) process can be used to form a second oxide layer 143 on the surface of the high-dielectric-constant material layer 142 to enhance the isolation effect, resulting in a deep trench isolation structure 140. The materials of the second oxide layer 143 and the first oxide layer 141 can be the same or different.

[0039] However, researchers conducted experimental tests on image sensors containing deep trench isolation structures manufactured using the above method and found that the deep trench isolation structures failed to achieve effective isolation between pixels. The leakage current between image sensor pixels was large and crosstalk was obvious, making it difficult to meet the manufacturing process requirements in terms of imaging performance and production yield.

[0040] Please see Figure 4 Researchers used scanning electron microscopy (SEM) to observe a portion of the structure near the deep trench isolation structure in an image sensor and discovered voids within the deep trench isolation structure that were not filled with isolation material. Figure 4 (The part circled by the white dashed line).

[0041] Please continue reading. Figure 2 and Figure 3Further investigation reveals that the voids 144 within the deep trench isolation structure 140 are due to the large depth-to-width ratio of the isolation trenches 111 formed by dry etching. During the filling of the isolation trenches 111 with isolation materials such as oxides and high dielectric constant materials, a "premature sealing" phenomenon can easily occur. That is, the opening at the top of the isolation trench 111 closes prematurely before the interior is completely filled with isolation material, resulting in voids 144 within the isolation trenches 111. This, in turn, reduces the integrity of the deep trench isolation structure 140 and weakens the isolation effect.

[0042] Therefore, it is necessary to provide a method for manufacturing semiconductor structures that reduces the voids inside deep trench isolation structures that are not filled with isolation material.

[0043] Please see Figure 5 This application provides a method for manufacturing a semiconductor structure. The method may include steps S110, S120, S130, S140, and S150.

[0044] S110: Provides a substrate.

[0045] Please refer to the following: Figure 6 and Figure 7 In this embodiment, the step of providing a substrate may include: providing a transition substrate 200; wherein the transition substrate 200 may include a substrate 210, a sacrificial layer 220 formed on the surface of the substrate 210, and a photolithography functional layer 230 formed on the side of the sacrificial layer 220 away from the substrate 210; etching the sacrificial layer 220 based on the photolithography functional layer 230 to form a sacrificial structure 221, thereby obtaining a substrate 300.

[0046] In this embodiment, the substrate 210 can serve as the basis for forming the semiconductor structure. Specifically, the substrate 210 can be composed of semiconductor materials, insulating materials, conductive materials, or any combination thereof. For example, the substrate 210 can be made of materials such as silicon (Si), silicon germanium (SiGe), silicon germanium carbon (SiGeC), or silicon carbide (SiC). The substrate 210 can be a single-layer structure or a multi-layer structure. In this embodiment, a silicon wafer 110 prepared by epitaxy is used as the substrate 210 to reduce lattice defects within the substrate 210.

[0047] In this embodiment, the sacrificial layer 220 can be used to provide a basis for the formation of the sacrificial structure 221. Specifically, to reduce the process complexity of subsequently removing the sacrificial structure 221 and the impact of removing the sacrificial structure 221 on the isolation structure and the substrate 210, the material of the sacrificial layer 220 can be carbon. The thickness of the sacrificial layer 220 is defined as the distance between the surface of the sacrificial layer 220 away from the substrate 210 and the surface of the sacrificial layer 220 closer to the substrate 210. The thickness of the sacrificial layer 220 can then be determined according to the process size requirements of the deep trench isolation structure in the image sensor. The sacrificial layer 220 can be formed by chemical vapor deposition or plasma-enhanced chemical vapor deposition processes.

[0048] In this embodiment, the photolithography functional layer 230 can be used to define the position and shape of the sacrificial structure 221. Specifically, the photolithography functional layer 230 may include a protective layer 231 and a photoresist layer 232. The protective layer 231 can serve as an interfacial chemical barrier between the sacrificial layer 220 and the photoresist layer 232, reducing the chemical interaction between the photoresist layer 232 and the sacrificial layer 220 during the etching process based on the photoresist layer 232, thus protecting the structural integrity of the sacrificial structure 221. The material of the protective layer 231 can be an oxide. The photoresist layer 232 can serve as a mask for etching the sacrificial layer 220, and the material of the photoresist layer 232 can be photoresist.

[0049] In this embodiment, a dry etching process can be used to etch away the portion of the sacrificial layer 220 that is not blocked by the photoresist layer 232. An end point detection (EPD) method is used to stop the etching on the surface of the substrate 210, forming a sacrificial structure 221 that protrudes from the surface of the substrate 210, resulting in a substrate 300 including the substrate 210 and the sacrificial structure 221.

[0050] S120: An insulating material layer forming the surface of the sacrificial structure and the substrate.

[0051] To ensure that the isolation structure is completely filled with isolation material, the process of forming a gate sidewall on the side of the dummy gate can be referenced. The position of the isolation structure on the substrate can be determined by using a sacrificial structure, and the sacrificial structure can be used as the attachment basis in the formation process of the isolation structure.

[0052] In this embodiment, the step of forming an isolation material layer covering the surface of the sacrificial structure and the surface of the substrate may include sub-steps S121, S122, S123, S124 and S125.

[0053] S121: A transition buffer layer, a transition conductive layer, and a transition isolation layer are sequentially deposited on the surface of the sacrificial structure and the surface of the substrate.

[0054] Please see Figure 8In this embodiment, the transition buffer layer 241 can be used to form a buffer portion of the isolation structure. The transition isolation layer 243 can be used to form an isolation portion of the isolation structure. The transition conductive layer 242 can be used to form a conductive structure. The materials of the transition buffer layer 241 and the transition isolation layer 243 can be the same. The material of the transition conductive layer 242 can be different from the materials of the transition buffer layer 241 and the transition isolation layer 243. Specifically, the materials of the transition buffer layer 241 and the transition isolation layer 243 can both be oxides; for example, the materials of the transition buffer layer 241 and the transition isolation layer 243 can be silicon oxide. The material of the transition conductive layer 242 can be a high dielectric constant material with conductivity; for example, the material of the transition conductive layer 242 can be one or a combination of hafnium oxide (HfO2), zirconium oxide (ZrO2), titanium oxide (TiO2), and lanthanum oxide (La2O3).

[0055] S122: Remove portions of the transition isolation layer located on the side of the sacrificial structure away from the substrate and on the side of the transition conductive layer away from the substrate.

[0056] To reduce crosstalk between pixels in an image sensor, a conductive structure can be used to guide leakage current between pixels to the ground terminal. Therefore, a conductive loop needs to be formed within the isolation structure. To form a conductive loop using the deposited transition conductive layer, part of the transition isolation layer can be removed first, exposing the transition conductive layer.

[0057] Please see Figure 9 In this embodiment, a dry etching process can be used to etch away a portion of the transition isolation layer 243 located on the side of the sacrificial structure 221 away from the substrate 210 and on the side of the transition conductive layer 242 away from the substrate 210. An endpoint detection method is used to stop the etching at the surface of the transition conductive layer 242. After etching, the remaining portion 243a of the removed transition isolation layer only retains the portion of the transition conductive layer 242 covering the side of the sacrificial structure 221.

[0058] S123: Material of the transition conductive layer is deposited on the side of the transition conductive layer away from the sacrificial structure and on the side of the transition conductive layer away from the substrate, and a deposited conductive layer is formed based on the transition conductive layer.

[0059] Please see Figure 10In this embodiment, the material of the transition conductive layer 242 can be recapped, and the deposited material and the transition conductive layer 242 together constitute the deposited conductive layer 242a. Since the portion of the transition conductive layer 242 covering the side of the sacrificial structure 221 is covered by the removed portion 243a of the transition isolation layer, during the deposition of the material of the transition conductive layer 242, some material is deposited on the surface of the removed portion 243a of the transition isolation layer away from the sacrificial structure 221, and the formed deposited conductive layer 242a can surround the removed portion 243a of the transition isolation layer.

[0060] S124: Remove portions of the deposited conductive layer located on the side of the sacrificial structure away from the substrate and on the side of the transition buffer layer away from the substrate.

[0061] Since the remaining portion of the conductive layer surrounding the transition isolation layer is removed, the isolation effect of the isolation structure can be improved by utilizing the removal of the remaining portion of the transition isolation layer to achieve isolation between different lines within the conductive circuit.

[0062] Please see Figure 11 In this embodiment, a dry etching process can be used to etch away portions of the deposited conductive layer 242a located on the side of the sacrificial structure 221 away from the substrate 210 and on the side of the transition buffer layer 241 away from the substrate 210. An endpoint detection method is used to stop the etching at the surface of the transition buffer layer 241. After etching, the remaining portion 242b of the deposited conductive layer retains portions of the side and bottom surfaces surrounding the remaining portion 243a of the transition isolation layer.

[0063] To improve the flatness of the plane formed by the remaining portion 242b of the deposited conductive layer, the remaining portion 243a of the transition isolation layer, and the sacrificial structure 221 after partial removal of the deposited conductive layer 242a, in some embodiments, chemical mechanical polishing (CMP) can be used to remove the portion of the deposited conductive layer 242a located on the side of the sacrificial structure 221 away from the substrate 210, and then dry etching can be used to etch and remove the portion of the deposited conductive layer 242a located on the side of the transition buffer layer 241 away from the substrate 210. During the polishing and etching process, an endpoint detection method can be used to stop the polishing or etching on the surface of the transition buffer layer 241.

[0064] S125: Deposit the material of the transition buffer layer on the side of the transition buffer layer away from the sacrificial structure and on the side of the transition buffer layer away from the substrate, and form a deposited buffer layer based on the transition buffer layer to obtain an isolation material layer.

[0065] To improve the imaging performance of image sensors, it is necessary to reduce the contact between conductive high-dielectric-constant materials and photosensitive materials. Therefore, a deposited buffer layer can be used to surround the removed portion of the deposited conductive layer, thereby isolating the removed portion of the deposited conductive layer and the photosensitive material during the subsequent formation of the photosensitive structure.

[0066] Please see Figure 12 In this embodiment, the material of the transition buffer layer 241 can be recapped, and the deposited material and the transition buffer layer 241 together constitute the deposited buffer layer 241a. Since the portion of the transition buffer layer 241 covering the side of the sacrificial structure 221 is covered by the structure formed by the removed portion 242b of the deposited conductive layer and the removed portion 243a of the transition isolation layer, during the deposition of the material of the transition buffer layer 241, some material is deposited on the surface of the removed portion 242b of the deposited conductive layer away from the sacrificial structure 221, and the formed deposited buffer layer 241a can surround the removed portion 242b of the deposited conductive layer.

[0067] In this embodiment, the isolation material layer 240 may consist of a deposited buffer layer 241a, a removed portion 242b of the deposited conductive layer, and a removed portion 243a of the transition isolation layer.

[0068] S130: Remove the isolation material layer covering the surface of the sacrificial structure away from the substrate and the surface of part of the substrate, and retain the isolation material layer covering the side of the sacrificial structure.

[0069] Since the multilayer material forming the isolation structure has been covered on the surface of the sacrificial structure and part of the substrate, and the multiple depositions are supported by the sacrificial structure protruding from the substrate surface, the voids caused by the deposition of isolation material into the trench are reduced, thus improving the structural integrity of the isolation structure.

[0070] Please see Figure 13 In this embodiment, a dry etching process can be used to etch away the surface of the sacrificial structure 221 away from the substrate 210 and the isolation material layer covering part of the substrate 210 surface. An endpoint detection method is used to stop the etching at the surface of the substrate 210. After etching, the isolation material layer retains a portion covering the side of the sacrificial structure 221.

[0071] To improve the flatness of the plane formed by the remaining portion 241b of the deposited buffer layer, the remaining portion 242b of the deposited conductive layer, the remaining portion 243a of the transition isolation layer, and the sacrificial structure 221 after partial removal of the deposited buffer layer 241a, in some embodiments, chemical mechanical polishing can be used to remove a portion of the isolation material layer covering the surface of the sacrificial structure 221 away from the substrate 210, and an endpoint detection method can be used to stop the polishing at the surface of the sacrificial structure 221. Then, a dry etching process is used to etch away the portion of the isolation material layer covering the surface of the substrate 210, and an endpoint detection method is used to stop the etching at the surface of the substrate 210.

[0072] S140: Remove the sacrificial structure to form at least two isolation structures protruding from the surface of the substrate.

[0073] After retaining the isolation material layer covering the sides of the sacrificial structure, the sacrificial structure can be removed, thereby forming at least two spaced isolation structures. Forming the isolation structures using this method reduces the damage to the silicon wafer caused by the high etching bias power during the formation of deep trench isolation structures using the etching-then-filling method in related technologies.

[0074] Please refer to the following: Figure 13 and Figure 14 To reduce damage to the substrate 210 and isolation structure 250 during the removal of the sacrificial structure 221, improve the removal efficiency of the sacrificial structure 221, and reduce sacrificial structure 221 residue, in this embodiment, the removal of the sacrificial structure may include: removing the sacrificial structure 221 using an automatic stripping process. Specifically, since the sacrificial structure 221 is formed by etching the sacrificial layer 220, and the material of the sacrificial structure 221 is carbon, the sacrificial structure 221 can be decomposed into soluble substances using oxyfluorinated carbon solvents or strong acid / base solutions, and then removed by cleaning.

[0075] In this embodiment, the isolation structure 250 may include a buffer portion, a conductive portion, and an isolation portion. The buffer portion is essentially the remaining portion 241b after the deposition of the buffer layer, and its function is similar to the first oxide layer in the deep trench isolation structure provided in the related art. The conductive portion is essentially the remaining portion 242b after the deposition of the conductive layer, and its function is similar to the high dielectric constant material layer in the deep trench isolation structure provided in the related art. The isolation portion is essentially the remaining portion 243a after the removal of the transition isolation layer, and its function is similar to the second oxide layer in the deep trench isolation structure provided in the related art. The functions of the buffer portion, conductive portion, and isolation portion will not be elaborated further here.

[0076] S150: A photoelectric sensing structure is formed between adjacent isolation structures to obtain a semiconductor structure.

[0077] Please see Figure 15In related technologies, the photoelectric sensing material of image sensors is silicon, which is a single material with low photoelectric conversion efficiency, resulting in low imaging performance. Therefore, to improve the photoelectric conversion efficiency of image sensors, in this embodiment, the photoelectric sensing structure 260 may include at least two photoelectric sensing material layers. Specifically, to ensure that different photoelectric sensing material layers have the same doping type, the doping elements in at least two photoelectric sensing material layers within the photoelectric sensing structure 260 are elements from the same main group. For example, the doping elements can all be Group V elements, that is, the doping elements can be nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi), and molybdenum (Mc). To improve the photoelectric conversion efficiency of the photoelectric sensing structure 260, the doping elements in adjacent photoelectric sensing material layers can be different.

[0078] To enhance the photosensitivity of the image sensor, in this embodiment, the relative atomic mass of the ions doped in at least two photosensitive material layers gradually decreases along the direction away from the substrate 210. Therefore, the relative atomic mass of the ions doped in the photosensitive material layer closer to the substrate 210 is larger, which can improve the stability of the photosensitive structure 260, while the relative atomic mass of the ions doped in the photosensitive material layer farther from the substrate 210 is smaller, which can provide more free electrons and increase the photosensitive current of the photosensitive structure 260 under light-driven conditions.

[0079] In some embodiments, different doping elements can be achieved in adjacent photosensitive material layers through ion implantation at different depths. Specifically, a silicon layer of a certain thickness can be deposited between adjacent isolation structures 250, and then different element ions can be implanted into the silicon using different ion implantation energies.

[0080] However, introducing different doped ions into different photosensitive material layers via ion implantation may damage the photosensitive material layers. To reduce internal defects in the photosensitive material layers and improve the photoelectric conversion performance of the photosensitive structure 260, in this embodiment, a photosensitive structure is formed between adjacent isolation structures. This can include: using an epitaxial growth process to grow at least two photosensitive material layers in segments between adjacent isolation structures 250. Taking a photosensitive structure 260 comprising three photosensitive material layers as an example, an epitaxial growth process can be used to first grow a first photosensitive material layer 261 doped with antimony on the surface of the substrate 210, then grow a second photosensitive material layer 262 doped with arsenic on the surface of the first photosensitive material layer 261 away from the substrate 210, and finally grow a third photosensitive material layer 263 doped with phosphorus on the surface of the second photosensitive material layer 262 away from the substrate 210, thus forming the photosensitive structure 260.

[0081] Please see Figure 16To facilitate the conduction of leakage current in the conductive portion of the isolation structure 250, in some embodiments, after the step of forming a photosensitive structure between adjacent isolation structures, the method for manufacturing the semiconductor structure may further include: depositing a conductive material on the side of the isolation structure 250 and the photosensitive structure 260 away from the substrate 210 to form a connecting conductive layer 270.

[0082] In this embodiment, the material deposited can be the same as the material of the deposited conductive layer 242a. The remaining portion 242b of the deposited conductive layer is removed. That is, the conductive portion of the isolation structure 250 and the connecting conductive layer 270 can form a conductive structure 290. The conductive structure 290 can be used to guide the leakage current to the ground terminal, thereby reducing the interference of the leakage current on imaging.

[0083] To improve the isolation between different interconnect layers, in some embodiments, a dielectric layer 280 may be formed on the side of the conductive layer 270 away from the substrate 210. Specifically, the dielectric layer 280 may be made of an oxide.

[0084] Please continue reading. Figure 15 Another embodiment of this application provides a semiconductor structure that may include a substrate 210, an isolation structure 250, and a photosensitive structure 260. This semiconductor structure can be manufactured using the semiconductor structure manufacturing method described in the above embodiments.

[0085] Another embodiment of this application provides an image sensor, which may include a semiconductor structure manufactured by the semiconductor structure manufacturing method described in the above embodiments, or the image sensor may include the semiconductor structure described in the above embodiments.

[0086] For other technical effects of the semiconductor structure and image sensor described in the above embodiments, please refer to other embodiments of this application for comparison and explanation, and they will not be repeated here.

[0087] In the semiconductor structure manufacturing method, semiconductor structure, and image sensor provided in this application embodiment, by forming an isolation material layer covering the surface of the sacrificial structure protruding from the substrate surface and the substrate surface, removing the isolation material layer on the surface of the sacrificial structure away from the substrate and part of the substrate surface while retaining the isolation material layer on the side of the sacrificial structure, and then removing the sacrificial structure to form at least two isolation structures protruding from the substrate surface, and forming a photosensitive structure including at least two photosensitive material layers between adjacent isolation structures, unexpected effects are achieved. These effects include: by covering the surface of the sacrificial structure protruding from the substrate surface and the substrate surface with isolation material layers, then removing part of the isolation material layer while retaining the isolation material layer on the side of the sacrificial structure as an isolation structure, and using a manufacturing process similar to that of a gate sidewall to manufacture the isolation structure, the unfilled voids inside the isolation structure are reduced, improving the integrity of the isolation structure and enhancing its isolation effect. Furthermore, by doping different elements belonging to the same main group into adjacent photosensitive material layers, the photoelectric conversion efficiency of the photosensitive structure is improved.

[0088] It is understood that the specific examples in this application are only intended to help those skilled in the art better understand the embodiments of this application, and are not intended to limit the scope of this application.

[0089] It is understood that in the various embodiments of this application, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not limit the implementation process of the embodiments of this application in any way.

[0090] It is understood that the various embodiments described in this application can be implemented individually or in combination, and the embodiments of this application are not limited in this respect.

[0091] Unless otherwise stated, all technical and scientific terms used in the embodiments of this application have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items. The singular forms "a," "the," and "the" as used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0092] As will be understood from the several embodiments provided in this application, the disclosed semiconductor structures and image sensors can be implemented in other ways. For example, the embodiments of the semiconductor structures and image sensors described above are merely illustrative.

[0093] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for manufacturing a semiconductor structure, characterized in that, The method for manufacturing the semiconductor structure includes: A substrate is provided; wherein the substrate includes a substrate and a sacrificial structure protruding from the surface of the substrate; An insulating material layer is formed covering the surface of the sacrificial structure and the surface of the substrate; Remove the insulating material layer covering the surface of the sacrificial structure away from the substrate and the surface of the substrate, while retaining the insulating material layer covering the side of the sacrificial structure; Remove the sacrificial structure to form at least two isolation structures protruding from the surface of the substrate; A photoelectric sensing structure is formed between adjacent isolation structures to obtain the semiconductor structure.

2. The method for manufacturing a semiconductor structure according to claim 1, characterized in that, The photoelectric sensing structure includes at least two photoelectric sensing material layers; within the photoelectric sensing structure, the doping elements in the at least two photoelectric sensing material layers are elements from the same main group. The doping elements in adjacent photoelectric sensing material layers are different.

3. The method for manufacturing a semiconductor structure according to claim 2, characterized in that, Along the direction away from the substrate, the relative atomic mass of the ions doped in the at least two photosensitive material layers gradually decreases.

4. The method for manufacturing a semiconductor structure according to claim 2, characterized in that, A photoelectric sensing structure is formed between adjacent isolation structures, comprising: At least two photosensitive material layers are grown in segments between adjacent isolation structures using an epitaxial growth process.

5. The method for manufacturing a semiconductor structure according to claim 1, characterized in that, The step of forming an insulating material layer covering the surface of the sacrificial structure and the surface of the substrate includes: A transition buffer layer, a transition conductive layer, and a transition isolation layer are sequentially deposited on the surface of the sacrificial structure and the surface of the substrate; wherein the material of the transition buffer layer and the material of the transition isolation layer are the same; and the material of the transition conductive layer is different from the materials of the transition buffer layer and the transition isolation layer. Remove portions of the transition isolation layer located on the side of the sacrificial structure away from the substrate and on the side of the transition conductive layer away from the substrate; Material of the transition conductive layer is deposited on the side of the transition conductive layer away from the sacrificial structure and on the side of the transition conductive layer away from the substrate, and a deposited conductive layer is formed based on the transition conductive layer; wherein the deposited conductive layer surrounds the removed portion of the transition isolation layer; Remove portions of the deposited conductive layer located on the side of the sacrificial structure away from the substrate and on the side of the transition buffer layer away from the substrate; Material of the transition buffer layer is deposited on the side of the transition buffer layer away from the sacrificial structure and on the side of the transition buffer layer away from the substrate, and a deposition buffer layer is formed based on the transition buffer layer to obtain the isolation material layer; wherein the deposition buffer layer surrounds the removed portion of the deposition conductive layer.

6. The method for manufacturing a semiconductor structure according to claim 5, characterized in that, After the step of forming a photosensitive structure between adjacent isolation structures, the method of manufacturing the semiconductor structure further includes: A conductive material is deposited on the side of the isolation structure and the photosensitive structure away from the substrate to form a connecting conductive layer; wherein the deposited conductive material is the same as the material of the deposited conductive layer; the remaining portion of the deposited conductive layer and the connecting conductive layer constitute a conductive structure.

7. The method for manufacturing a semiconductor structure according to claim 1, characterized in that, The material of the sacrificial structure is carbon; Removing the sacrificial structure includes: The sacrificial structure is removed using an automated peeling process.

8. The method for manufacturing a semiconductor structure according to claim 1, characterized in that, The steps for providing the substrate include: A transition substrate is provided; wherein the transition substrate includes the substrate, a sacrificial layer formed on the surface of the substrate, and a photolithographic functional layer formed on the side of the sacrificial layer away from the substrate; The sacrificial layer is etched based on the photolithography functional layer to form the sacrificial structure, thereby obtaining the substrate.

9. A semiconductor structure, characterized in that, The semiconductor structure is manufactured by the semiconductor structure manufacturing method as described in any one of claims 1 to 8.

10. An image sensor, characterized in that, The image sensor comprises a semiconductor structure manufactured by the manufacturing method of the semiconductor structure as described in any one of claims 1 to 8, or the image sensor comprises the semiconductor structure as described in claim 9.

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