Image sensor and preparation method thereof, and electronic device

Abstract

The present application relates to an image sensor and a method for preparing the same, and an electronic device, including: a substrate, a plurality of isolation structures, and a plurality of photodiodes, wherein the isolation structures are arranged in intervals in the substrate, and the photodiodes are arranged between adjacent isolation structures, and the isolation structure includes: a first isolation layer, located in the substrate; a first high dielectric constant dielectric layer, located on a side of the first isolation layer away from the substrate; a reflective layer, located on a side of the first high dielectric constant dielectric layer away from the first isolation layer; a second high dielectric constant dielectric layer, located on a side of the reflective layer away from the first high dielectric constant dielectric layer; wherein the reflective layer has the same elements as at least one of the first high dielectric constant dielectric layer or the second high dielectric constant dielectric layer. The image sensor of the present application can avoid the second high dielectric constant dielectric layer from gathering at the bottom of the isolation structure, improve the uniformity of the sidewall of the isolation structure, and thus improve the reflection efficiency.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to an image sensor and a preparation method thereof, and an electronic device. Background Art

[0002] With the development of semiconductor technology, backside illumination image sensors (BSI) have been widely used due to their high light utilization rate and good imaging quality in low-light environments.

[0003] In the traditional BSI process, multiple layers of high dielectric constant materials are usually deposited on the isolation structure to form an isolation structure with better performance. However, in the process of depositing high dielectric constant materials, due to the poor mechanical properties of the interface between different high dielectric constant materials, the later deposited high dielectric constant materials are easily accumulated at the bottom of the trench structure, affecting the device performance. Summary of the invention

[0004] Based on this, it is necessary to provide an image sensor and a preparation method and an electronic device thereof that can prevent high dielectric constant materials from gathering at the bottom of an isolation structure.

[0005] In a first aspect, the present application provides an image sensor, comprising a substrate, a plurality of isolation structures, and a plurality of photodiodes, wherein the isolation structures are arranged in the substrate at intervals, the photodiodes are arranged between adjacent isolation structures, and the isolation structures include:

[0006] A first isolation layer, located in the substrate;

[0007] A first high dielectric constant dielectric layer, located on a side of the first isolation layer away from the substrate;

[0008] a reflective layer, located on a side of the first high dielectric constant dielectric layer away from the first isolation layer;

[0009] A second high dielectric constant dielectric layer is located on a side of the reflective layer away from the first high dielectric constant dielectric layer;

[0010] The reflective layer has the same element as at least one of the first high dielectric constant medium layer or the second high dielectric constant medium layer.

[0011] In one embodiment, the reflective layer has the same metal element as the first high dielectric constant medium layer and the second high dielectric constant medium layer.

[0012] In one embodiment, the first high dielectric constant dielectric layer includes at least one of aluminum oxide, tantalum oxide or hafnium oxide, the second high dielectric constant dielectric layer includes at least one of aluminum oxide, tantalum oxide or hafnium oxide, and the reflective layer includes at least one of aluminum tantalum compound, aluminum hafnium compound or tantalum hafnium compound.

[0013] In one embodiment, the isolation structure further includes:

[0014] The second isolation layer is arranged on a side of the second high dielectric constant medium layer away from the reflective layer.

[0015] In one embodiment, the thickness of the first high dielectric constant dielectric layer is 40Å-100Å, the thickness of the reflective layer is 10Å-60Å, and the thickness of the second high dielectric constant dielectric layer is 450Å-560Å.

[0016] In a second aspect, the present application also provides a method for preparing an image sensor, comprising:

[0017] Providing a substrate, wherein a plurality of grooves distributed at intervals are arranged in the substrate;

[0018] forming a first isolation material layer on the sidewall and bottom of the trench;

[0019] forming a first high dielectric constant material layer on a side of the first isolation material layer away from the substrate;

[0020] forming a reflective material layer on a side of the first high dielectric constant material layer away from the first isolation material layer;

[0021] forming a second high dielectric constant material layer on a side of the reflective material layer away from the first high dielectric constant material layer; wherein the reflective material layer has the same element as at least one of the first high dielectric constant material layer or the second high dielectric constant material layer;

[0022] The first isolation material layer, the first high dielectric constant material layer, the reflective material layer and the second high dielectric constant material layer located outside the groove are removed to form a first isolation layer, a first high dielectric constant dielectric layer, a reflective layer and a second high dielectric constant dielectric layer; the first isolation layer, the first high dielectric constant dielectric layer, the reflective layer and the second high dielectric constant dielectric layer constitute an isolation structure;

[0023] A photodiode is formed between adjacent isolation structures.

[0024] In one embodiment, forming a second high dielectric constant material layer on a side of the reflective material layer away from the first high dielectric constant material layer comprises:

[0025] Through a deposition process, a second high dielectric constant material is deposited on a side of the reflective layer away from the first high dielectric constant material layer to form the second high dielectric constant material layer.

[0026] In one embodiment, forming a second high dielectric constant material layer on a side of the reflective material layer away from the first high dielectric constant material layer comprises:

[0027] Depositing a metal material on a side of the reflective material layer away from the first high dielectric constant material layer;

[0028] The obtained structure is subjected to a heat treatment to oxidize at least a portion of the metal material into a metal oxide to form the second high dielectric constant material layer.

[0029] In a third aspect, the present application provides another image sensor, comprising a substrate, a plurality of isolation structures, a plurality of photodiodes and a plurality of isolation grids, wherein the isolation structures are arranged in the substrate at intervals, the photodiodes are arranged between adjacent isolation structures, the isolation grids are arranged on the substrate and corresponding to the isolation structures, and the isolation grids include:

[0030] A first high dielectric constant dielectric layer, located on the substrate;

[0031] A reflective layer, located on a side of the first high dielectric constant dielectric layer away from the substrate;

[0032] A second high dielectric constant dielectric layer is located on a side of the reflective layer away from the first high dielectric constant dielectric layer;

[0033] The reflective layer has the same element as at least one of the first high dielectric constant medium layer or the second high dielectric constant medium layer.

[0034] In a fourth aspect, the present application also provides an electronic device, which includes the image sensor provided by any of the above embodiments.

[0035] The unexpected effect of the present application is that the image sensor includes a substrate, an isolation structure and a plurality of photodiodes, the isolation structures are arranged in the substrate at intervals, and the photodiodes are arranged between adjacent isolation structures. The isolation structure includes a first isolation layer, a first high dielectric constant dielectric layer, a reflective layer and a second high dielectric constant dielectric layer, wherein the first isolation layer is located in the substrate, the first isolation layer can prevent the first high dielectric constant dielectric layer, the reflective layer and the second high dielectric constant dielectric layer formed subsequently from being broken down, the first high dielectric constant dielectric layer is located on the side of the first isolation layer away from the substrate, the reflective layer is located on the side of the first high dielectric constant dielectric layer away from the first isolation layer, and the second high dielectric constant dielectric layer is located on the side of the reflective layer away from the first high dielectric constant dielectric layer. Since the reflective layer has the same element as at least one of the first high dielectric constant dielectric layer or the second high dielectric constant dielectric layer, the reflective layer has a higher bonding force with the first high dielectric constant dielectric layer or the reflective layer has a higher bonding force with the second high dielectric constant dielectric layer, thereby avoiding the situation where the high dielectric constant material is gathered at the bottom of the isolation structure, improving the uniformity of the side wall of the isolation structure, and thus improving the reflection efficiency. In addition, since the added reflective layer itself has a higher reflectivity, the reflective efficiency of the isolation structure can be further improved, crosstalk between photodiodes can be avoided, and product performance can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 is a schematic diagram of a cross-sectional structure of an image sensor provided in an embodiment;

[0038] Figure 2 is a schematic diagram of a cross-sectional structure of an isolation structure in an image sensor provided in an embodiment;

[0039] Figure 3 is a flow chart of a method for preparing an image sensor provided in an embodiment;

[0040] Figure 4 is a schematic cross-sectional view of a structure obtained in step S500 in a method for preparing an image sensor provided in an embodiment;

[0041] Figure 5 FIG. 4 is a schematic diagram of a cross-sectional structure of an image sensor provided in another embodiment.

[0042] Description of reference numerals:

[0043] 100-substrate, 200-isolation structure, 210-first isolation layer, 211-first isolation material layer, 220-first high dielectric constant dielectric layer, 221-first high dielectric constant material layer, 230-reflection layer, 231-reflection material layer, 240-second high dielectric constant dielectric layer, 241-second high dielectric constant material layer, 250-second isolation layer, 300-photodiode, 400-isolation grid. DETAILED DESCRIPTION

[0044] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0046] It should be understood that when an element or layer is referred to as being "on," "adjacent to," "connected to," or "coupled to" another element or layer, it may be directly on, adjacent to, connected to, or coupled to the other element or layer, or there may be intervening elements or layers. Conversely, when an element is referred to as being "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" another element or layer, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc. may be used to describe various layers, these layers should not be limited by these terms. These terms are merely used to distinguish one layer from another. Therefore, without departing from the teachings of the present invention, the first layer discussed below may be represented as the second layer; for example, the first high dielectric constant dielectric layer may be referred to as the second high dielectric constant dielectric layer, and similarly, the second high dielectric constant dielectric layer may be referred to as the high dielectric constant dielectric layer; the first high dielectric constant dielectric layer and the second high dielectric constant dielectric layer are different high dielectric constant dielectric layers.

[0047] Spatially relative terms such as "under," "beneath," "below," "under," "above," "above," and the like may be used herein to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that, in addition to the orientations shown in the figures, spatially relative terms also include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is flipped, an element or feature described as "under other elements" or "under it" or "under it" will be oriented as being "above" the other elements or features. Thus, the exemplary terms "under" and "under" may include both upper and lower orientations. In addition, the device may also include additional orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptors used herein are interpreted accordingly.

[0048] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. At the same time, in this specification, the term "and / or" includes any and all combinations of the relevant listed items.

[0049] Embodiments of the invention are described herein with reference to cross-sectional views which are schematic representations of idealized embodiments (and intermediate structures) of the invention, and variations in the shapes shown due to, for example, manufacturing techniques and / or tolerances are contemplated. Thus, embodiments of the invention should not be limited to the particular shapes of the regions shown herein, but rather include deviations in shapes due to, for example, manufacturing techniques. The regions shown in the figures are schematic in nature, and their shapes do not represent the actual shapes of the regions of the device, and do not limit the scope of the invention.

[0050] In the traditional BSI process, multiple layers of high dielectric constant materials are usually deposited on the isolation structure to form an isolation structure with better performance. However, in the process of depositing high dielectric constant materials, due to the poor mechanical properties of the interface between different high dielectric constant materials, the later deposited high dielectric constant materials are easily accumulated at the bottom of the trench structure, affecting the device performance.

[0051] Based on this, Figure 1 As shown, the present application provides an image sensor, including a substrate 100 , a plurality of isolation structures 200 , and a plurality of photodiodes 300 . The isolation structures 200 are arranged at intervals in the substrate 100 , and the photodiodes 300 are arranged between adjacent isolation structures 200 .

[0052] The material of the substrate 100 may be any suitable substrate material known in the art, for example, at least one of the following materials: silicon (Si), germanium (Ge), red phosphorus, silicon germanium (SiGe), silicon carbide (SiC), carbon germanium silicon (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP) or other III / V compound semiconductors, including multilayer structures composed of these semiconductors, or silicon on insulator (SOI), stacked silicon on insulator (SSOI), stacked silicon germanium on insulator (S-SiGeOI), silicon germanium on insulator (SiGeOI) and germanium on insulator (GeOI), or double-sided polished silicon wafers (Double Side Polished Wafers, DSP), or ceramic substrates such as alumina, quartz or glass substrates, etc., which are not limited in this embodiment.

[0053] The isolation structure 200 includes a first isolation layer 210, a first high dielectric constant dielectric layer 220, a reflective layer 230 and a second high dielectric constant dielectric layer 240, wherein the first isolation layer 210 is located in the substrate 100, the first high dielectric constant dielectric layer 220 is located on a side of the first isolation layer 210 away from the substrate 100, the reflective layer 230 is located on a side of the first high dielectric constant dielectric layer 220 away from the first isolation layer 210, and the second high dielectric constant dielectric layer 240 is located on a side of the reflective layer 230 away from the first high dielectric constant dielectric layer 220. The reflective layer 230 has the same elements as at least one of the first high dielectric constant dielectric layer 220 or the second high dielectric constant dielectric layer 240.

[0054] The first isolation layer 210 may be at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide, etc. The material of the first high dielectric constant layer 220 is different from the material of the second high dielectric constant layer 240. The material of the first high dielectric constant layer 220 and the material of the second high dielectric constant layer 240 may be any suitable high dielectric constant material known in the art, for example, any high dielectric constant material such as aluminum oxide (AlO), tantalum oxide (TaO), hafnium oxide (HfO), zirconium oxide (ZrO), etc. The reflective layer 230 may have the same elements as the first high dielectric constant layer 220 and elements with similar properties to the second high dielectric constant layer 240; optionally, the reflective layer 230 may have the same elements as the second high dielectric constant layer 240 and elements with similar properties to the first high dielectric constant layer 220; optionally, the reflective layer 230 may include the same elements as the first high dielectric constant layer 220 and the same elements as the second high dielectric constant layer 240.

[0055] In the embodiment of the present application, the image sensor includes a substrate 100, an isolation structure 200 and a plurality of photodiodes 300, wherein the isolation structures 200 are arranged in the substrate 100 at intervals, and the photodiodes 300 are arranged between adjacent isolation structures 200. The isolation structure 200 includes a first isolation layer 210, a first high dielectric constant dielectric layer 220, a reflective layer 230 and a second high dielectric constant dielectric layer 240, wherein the first isolation layer 210 is located in the substrate 100, and the first isolation layer 210 can prevent the first high dielectric constant dielectric layer 220, the reflective layer 230 and the second high dielectric constant dielectric layer 240 formed subsequently from being broken down, the first high dielectric constant dielectric layer 220 is located on a side of the first isolation layer 210 away from the substrate 100, the reflective layer 230 is located on a side of the first high dielectric constant dielectric layer 220 away from the first isolation layer 210, and the second high dielectric constant dielectric layer 240 is located on a side of the reflective layer 230 away from the first high dielectric constant dielectric layer 220. Since the reflective layer 230 has the same elements as at least one of the first high dielectric constant dielectric layer 220 or the second high dielectric constant dielectric layer 240, the reflective layer 230 has a high bonding force with the first high dielectric constant dielectric layer 220, or the reflective layer 230 has a high bonding force with the second high dielectric constant dielectric layer 240, thereby avoiding the high dielectric constant material from gathering at the bottom of the isolation structure 200, improving the uniformity of the side wall of the isolation structure 200, and improving the reflection efficiency. In addition, since the added reflective layer 230 itself has a high reflectivity, the reflection efficiency of the isolation structure 200 can be further improved, avoiding crosstalk between the photodiodes 300, and improving product performance.

[0056] In one embodiment, the reflective layer 230 has the same metal element as the first high dielectric constant dielectric layer 220 and the second high dielectric constant dielectric layer 240. Specifically, the first high dielectric constant dielectric layer 220 includes at least one of aluminum oxide, tantalum oxide or hafnium oxide, the second high dielectric constant dielectric layer 240 includes at least one of aluminum oxide, tantalum oxide or hafnium oxide, and the reflective layer 230 includes at least one of aluminum tantalum compound, aluminum hafnium compound or tantalum hafnium compound.

[0057] Exemplarily, the first high dielectric constant dielectric layer 220 is aluminum oxide, the second high dielectric constant dielectric layer 240 is tantalum oxide, and the reflective layer 230 may be an aluminum tantalum compound (e.g., AlTa3); optionally, the first high dielectric constant dielectric layer 220 is aluminum oxide, the second high dielectric constant dielectric layer 240 is hafnium oxide, and the reflective layer 230 may be an aluminum hafnium compound (e.g., HfAlO); optionally, the first high dielectric constant dielectric layer 220 is tantalum oxide, the second high dielectric constant dielectric layer 240 is hafnium oxide, and the reflective layer 230 may be a tantalum hafnium compound (e.g., Ta4HfC5).

[0058] In this embodiment, since the reflective layer 230 has the same metal element as the first high dielectric constant dielectric layer 220 and the second high dielectric constant dielectric layer 240, respectively, the reflective layer 230 and the first high dielectric constant dielectric layer 220 and the second high dielectric constant dielectric layer 240 have a high bonding force, which can prevent the second high dielectric constant dielectric layer 240 from gathering at the bottom of the isolation structure, improve the uniformity of the side wall of the isolation structure, and improve the reflection efficiency. In addition, since the metal compound used in the reflective layer has a higher reflectivity than traditional isolation materials (such as silicon oxide, etc.), the reflection efficiency of the isolation structure can be further improved.

[0059] In one embodiment, Figure 2 As shown, the isolation structure further includes a second isolation layer 250. The second isolation layer 250 is disposed on a side of the second high dielectric constant dielectric layer 240 away from the reflective layer 230. The material of the second isolation layer 250 can be any one of silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide, etc. The second isolation layer 250 can be used to isolate the second high dielectric constant dielectric layer 240 from a structure formed later and located on the isolation structure.

[0060] In one embodiment, the thickness of the first high dielectric constant dielectric layer 220 is 40Å-100Å, for example, 40Å, 60Å, 80Å or 100Å, etc. The thickness of the reflective layer 230 is 10Å-60Å, for example, 10Å, 20Å, 30Å, 40Å, 50Å or 60Å, etc. The thickness of the second high dielectric constant dielectric layer 240 is 450Å-560Å, for example, 450Å, 480Å, 510Å, 540Å or 560Å, etc.

[0061] In one embodiment, Figure 3 As shown, the present application also provides a method for preparing an image sensor, including steps S100-S700.

[0062] S100, providing a substrate, wherein a plurality of grooves distributed at intervals are arranged in the substrate.

[0063] S200 , forming a first isolation material layer on the sidewall and bottom of the trench.

[0064] like Figure 4 As shown, a deposition process may be used to form a first isolation material layer 211 on the sidewall and bottom of the trench. The first isolation material layer 211 may be used to protect the first high dielectric constant dielectric layer 220, the reflective layer 230, and the second high dielectric constant dielectric layer 240 formed subsequently, and prevent the first high dielectric constant dielectric layer 220, the reflective layer 230, and the second high dielectric constant dielectric layer 240 from being broken down. The first isolation material layer 211 may be at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide, and the like.

[0065] S300 , forming a first high dielectric constant material layer on a side of the first isolation material layer away from the substrate.

[0066] Please continue reading Figure 4 The first high dielectric constant material layer 221 may be formed on the side of the first isolation material layer 211 away from the substrate by using a diffusion process, an atomic layer deposition process (ALD) or a physical vapor deposition process (PVD). For example, the first high dielectric constant material layer 221 may include any one of high dielectric constant materials such as aluminum oxide (AlO), tantalum oxide (TaO), hafnium oxide (HfO), and zirconium oxide (ZrO).

[0067] S400 , forming a reflective material layer on a side of the first high dielectric constant material layer away from the first isolation material layer.

[0068] Please continue reading Figure 4 The reflective material layer 231 may be formed on a side of the first high dielectric constant material layer 221 away from the first isolation material layer 211 by using a physical vapor deposition process (PVD) or a plasma enhanced atomic layer deposition process (PEALD).

[0069] S500, forming a second high dielectric constant material layer on a side of the reflective material layer away from the first high dielectric constant material layer, wherein the reflective material layer has the same element as at least one of the first high dielectric constant material layer or the second high dielectric constant material layer.

[0070] Please continue reading Figure 4 , the second high dielectric constant material layer 241 may fill the groove. Optionally, after forming the second high dielectric constant material layer 241, a second isolation material layer may be formed on a side of the second high dielectric constant material layer 241 away from the reflective material layer 231, the second isolation material layer fills the groove, and the second isolation material layer located above the groove is removed to form a second isolation layer 250.

[0071] S600, removing the first isolation material layer, the first high dielectric constant material layer, the reflective material layer and the second high dielectric constant material layer outside the trench to form a first isolation layer, a first high dielectric constant dielectric layer, a reflective layer and a second high dielectric constant dielectric layer.

[0072] The first isolation layer 210, the first high dielectric constant medium layer 220, the reflective layer 230 and the second high dielectric constant medium layer 240 constitute a Figure 1 An isolation structure 200 is shown.

[0073] S700 , forming a photodiode between adjacent isolation structures.

[0074] In this embodiment, a substrate having a plurality of grooves spaced apart is provided, a first isolation material layer 211 is formed on the sidewalls and bottom of the grooves, a first high dielectric constant material layer 221 is formed on a side of the first isolation material layer 211 away from the substrate, a reflective material layer 231 is formed on a side of the first high dielectric constant material layer 221 away from the first isolation material layer 211, and a second high dielectric constant material layer 241 is formed on a side of the reflective material layer 231 away from the first high dielectric constant material layer 221. The first isolation material layer 211, the first high dielectric constant material layer 221, the reflective material layer 231, and the second high dielectric constant material layer 241 located outside the grooves are removed to form a first isolation layer 210, a first high dielectric constant dielectric layer 220, a reflective layer 230, and a second high dielectric constant dielectric layer 240, thereby forming an isolation structure 200. Since the reflective material layer 231 has the same elements as at least one of the first high dielectric constant material layer 221 or the second high dielectric constant material layer 241, the reflective material layer 231 has a high bonding force with the first high dielectric constant material layer 221, and the reflective material layer 231 also has a high bonding force with the second high dielectric constant material layer 241, which can avoid the high dielectric constant material from gathering at the bottom of the isolation structure when the second high dielectric constant material layer 241 is formed, thereby improving the uniformity of the sidewall of the isolation structure formed and improving the reflection efficiency. Further, a photodiode 300 is formed between adjacent isolation structures.

[0075] It should be understood that although Figure 3 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 3 At least part of the steps may include multiple steps or multiple stages. These steps or stages are not necessarily performed at the same time, but can be performed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed in turn or alternately with other steps or at least part of the steps or stages in other steps.

[0076] In one embodiment, forming the second high dielectric constant material layer 241 on a side of the reflective material layer 231 away from the first high dielectric constant material layer 221 includes the step of depositing a second high dielectric constant material on a side of the reflective material layer 231 away from the first high dielectric constant material layer 221 through a deposition process.

[0077] The second high dielectric constant material may be any one of aluminum oxide (AlO), tantalum oxide (TaO), hafnium oxide (HfO), zirconium oxide (ZrO), etc. The second high dielectric constant material layer 241 may be formed by depositing the second high dielectric constant material layer on the side of the reflective material layer 231 away from the first high dielectric constant material layer 221 using a diffusion process, an atomic layer deposition process (ALD), or a physical vapor deposition process (PVD).

[0078] Optionally, in one embodiment, forming a second high dielectric constant material layer 241 on a side of the reflective material layer 231 away from the first high dielectric constant material layer 221 includes: depositing a metal material on a side of the reflective material layer 231 away from the first high dielectric constant material layer 221; and heat treating the resulting structure to oxidize at least part of the metal material into metal oxide to form the second high dielectric constant material layer 241.

[0079] It can be understood that a metal material such as aluminum, tantalum, hafnium or zirconium can be deposited on the side of the reflective material layer 231 away from the first high dielectric constant material layer 221, and then the structure is heat treated to oxidize at least part or all of the metal material into metal oxide to form a second high dielectric constant material layer 241.

[0080] In one embodiment, Figure 5 As shown, the present application also provides an image sensor, which includes a substrate 100, a plurality of isolation structures 200, a plurality of photodiodes 300 and a plurality of isolation grids 400, wherein the isolation structures 200 are arranged at intervals within the substrate 100, the photodiodes 300 are arranged between adjacent isolation structures 200, and the isolation grids 400 are arranged on the substrate 100 and corresponding to the isolation structures 200.

[0081] The isolation grid 200 includes a first high dielectric constant dielectric layer 220, a reflective layer 230 and a second high dielectric constant dielectric layer 240. The first high dielectric constant dielectric layer 220 is located on the substrate 100. The reflective layer 230 is located on a side of the first high dielectric constant dielectric layer 220 away from the substrate 100. The second high dielectric constant dielectric layer 240 is located on a side of the reflective layer 230 away from the first high dielectric constant dielectric layer 220. The reflective layer 230 has at least the same elements as one of the first high dielectric constant dielectric layer 220 or the second high dielectric constant dielectric layer 240. The first high dielectric constant dielectric layer 220, the reflective layer 230 and the second high dielectric constant dielectric layer 240 have been described in detail above and will not be repeated here.

[0082] Among them, the isolation structure 200 can have the same thin film structure as the isolation grid 400, that is, the isolation structure 200 can also include a film layer structure composed of a first high dielectric constant dielectric layer 220, a reflective layer 230 and a second high dielectric constant dielectric layer 240. The isolation structure 200 can also include a film layer structure composed of a first high dielectric constant dielectric layer 220 and a second high dielectric constant dielectric layer 240. The isolation structure can also be other commonly used film layer structures (such as silicon oxide, etc.), which is not limited to this embodiment.

[0083] In this embodiment, the isolation grid 400 includes a first high dielectric constant dielectric layer 220, a reflective layer 230, and a second high dielectric constant dielectric layer 240. Since the reflective layer 230 has the same element as at least one of the first high dielectric constant dielectric layer 220 or the second high dielectric constant dielectric layer 240, the reflective layer 230 has a higher bonding force with the first high dielectric constant dielectric layer 220 or the second high dielectric constant dielectric layer 240, thereby improving the bonding force between the film layers of the isolation grid 400 and the uniformity of the bonding interface.

[0084] In one embodiment, the present application further provides an electronic device, which includes the image sensor provided by any of the above embodiments.

[0085] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", "ideal embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.

[0086] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features of the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0087] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. An image sensor, characterized in that: The invention comprises a substrate, a plurality of isolation structures and a plurality of photodiodes, wherein the isolation structures are arranged in the substrate at intervals, the photodiodes are arranged between adjacent isolation structures, and the isolation structures comprise: A first isolation layer, located in the substrate; A first high dielectric constant dielectric layer, located on a side of the first isolation layer away from the substrate; a reflective layer, located on a side of the first high dielectric constant dielectric layer away from the first isolation layer; A second high dielectric constant dielectric layer is located on a side of the reflective layer away from the first high dielectric constant dielectric layer; The reflective layer has the same metal element as the first high dielectric constant medium layer and the second high dielectric constant medium layer respectively; the reflective layer has a high reflectivity, which can improve the reflection efficiency of the isolation structure; The thickness of the first high dielectric constant dielectric layer is 40Å-100Å, the thickness of the reflective layer is 10Å-60Å, and the thickness of the second high dielectric constant dielectric layer is 450Å-560Å.

2. The image sensor according to claim 1, characterized in that The first high dielectric constant dielectric layer includes at least one of aluminum oxide, tantalum oxide or hafnium oxide, the second high dielectric constant dielectric layer includes at least one of aluminum oxide, tantalum oxide or hafnium oxide, and the reflective layer includes at least one of aluminum tantalum compound, aluminum hafnium compound or tantalum hafnium compound.

3. The image sensor according to claim 1, characterized in that The isolation structure also includes: The second isolation layer is arranged on a side of the second high dielectric constant medium layer away from the reflective layer.

4. The image sensor according to claim 1, characterized in that The first isolation layer is at least one of silicon oxide, silicon nitride, silicon oxynitride, and silicon oxycarbide.

5. A method for preparing an image sensor, characterized in that: include: Providing a substrate, wherein a plurality of grooves distributed at intervals are arranged in the substrate; forming a first isolation material layer on the sidewall and bottom of the trench; forming a first high dielectric constant material layer on a side of the first isolation material layer away from the substrate; forming a reflective material layer on a side of the first high dielectric constant material layer away from the first isolation material layer; forming a second high dielectric constant material layer on a side of the reflective material layer away from the first high dielectric constant material layer; wherein the reflective material layer has the same metal element as the first high dielectric constant material layer and the second high dielectric constant material layer; The first isolation material layer, the first high dielectric constant material layer, the reflective material layer and the second high dielectric constant material layer located outside the groove are removed to form a first isolation layer, a first high dielectric constant dielectric layer, a reflective layer and a second high dielectric constant dielectric layer; the first isolation layer, the first high dielectric constant dielectric layer, the reflective layer and the second high dielectric constant dielectric layer constitute an isolation structure; forming a photodiode between adjacent isolation structures; Wherein, the reflective layer has a high reflectivity, which can improve the reflection efficiency of the isolation structure; The thickness of the first high dielectric constant dielectric layer is 40Å-100Å, the thickness of the reflective layer is 10Å-60Å, and the thickness of the second high dielectric constant dielectric layer is 450Å-560Å.

6. The method according to claim 5, characterized in that The forming of a second high dielectric constant material layer on a side of the reflective material layer away from the first high dielectric constant material layer comprises: Through a deposition process, a second high dielectric constant material is deposited on a side of the reflective layer away from the first high dielectric constant material layer to form the second high dielectric constant material layer.

7. The method according to claim 5, characterized in that The forming of a second high dielectric constant material layer on a side of the reflective material layer away from the first high dielectric constant material layer comprises: Depositing a metal material on a side of the reflective material layer away from the first high dielectric constant material layer; The obtained structure is subjected to a heat treatment to oxidize at least a portion of the metal material into a metal oxide to form the second high dielectric constant material layer.

8. An image sensor, characterized in that: The invention comprises a substrate, a plurality of isolation structures, a plurality of photodiodes and a plurality of isolation grids, wherein the isolation structures are arranged in the substrate at intervals, the photodiodes are arranged between adjacent isolation structures, the isolation grids are arranged on the substrate and corresponding to the isolation structures, and the isolation grids include: A first high dielectric constant dielectric layer, located on the substrate; A reflective layer, located on a side of the first high dielectric constant dielectric layer away from the substrate; A second high dielectric constant dielectric layer is located on a side of the reflective layer away from the first high dielectric constant dielectric layer; The reflective layer has the same metal element as the first high dielectric constant medium layer and the second high dielectric constant medium layer.

9. An electronic device, characterized in that: Comprising the image sensor according to any one of claims 1 to 4, or the image sensor according to claim 8.

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