Image sensor and manufacturing method thereof

Abstract

The present invention discloses an image sensor and a manufacturing method thereof, relating to the field of semiconductor technology. The manufacturing method comprises: providing a substrate, the substrate comprising a substrate and a plurality of first isolation structures located within the substrate, the plurality of first isolation structures being arranged at intervals, forming a first isolation layer of a first preset thickness on the substrate, and etching the first isolation layer to form a plurality of isolation grooves, wherein a first isolation layer of a second preset thickness is retained at the bottom of the isolation grooves, the orthographic projection of the first isolation layer between the isolation grooves on the substrate overlaps with the orthographic projection of the first isolation structure on the substrate, and forming a photoelectric functional layer within the isolation grooves so that the photoelectric functional layer forms a photodiode, thereby eliminating the need to use high-energy ion implantation to form the photodiode, thereby avoiding substrate surface damage and the resulting crosstalk problem between photodiodes.

Description

Technical Field

[0001] The present invention relates to the technical field of image sensors, and in particular to an image sensor and a manufacturing method thereof. Background Art

[0002] Complementary Metal Oxide Semiconductor (CMOS) image sensors are widely used in consumer electronics, security monitoring, assisted driving, and medical equipment due to their low cost, anti-blurring properties, and flexible access. CMOS image sensors include front-side illumination (FSI) and back-side illumination (BSI) sensors. BSI image sensors are widely used in applications requiring high pixel performance because they allow light to directly illuminate the photodiode (PD), improving device sensitivity and light utilization. Traditional BSI manufacturing methods use high-energy ion implantation (IMP) to form the photodiodes in the front-end process. However, this process can damage the substrate surface, leading to crosstalk between adjacent photodiodes. Summary of the Invention

[0003] The invention discloses an image sensor and a manufacturing method thereof, so as to solve the problems of substrate surface damage caused by ion implantation to form photodiodes and crosstalk between photodiodes.

[0004] In a first aspect, the present invention discloses a method for manufacturing an image sensor, comprising: providing a substrate, the substrate comprising a substrate and a plurality of first isolation structures located within the substrate; the plurality of first isolation structures being arranged at intervals; forming a first isolation layer of a first preset thickness on the substrate, and etching the first isolation layer to form a plurality of isolation grooves; retaining a first isolation layer of a second preset thickness at the bottom of the isolation grooves; the orthographic projection of the first isolation layer between the isolation grooves on the substrate overlaps with the orthographic projection of the first isolation structure on the substrate; forming a photoelectric functional layer within the isolation grooves so that the photoelectric functional layer forms a photodiode; the first isolation layer at the bottom of the isolation grooves is used to isolate the photoelectric functional layer from the substrate; the first isolation layer between the isolation grooves is used to isolate the photoelectric functional layers within adjacent isolation grooves.

[0005] In some embodiments of the present invention, after the photoelectric functional layer is formed in the isolation groove, the process further includes: forming a second isolation layer on the side of the photoelectric functional layer facing away from the substrate, and etching the second isolation layer to form a plurality of second isolation structures; the orthographic projection of the second isolation structure on the substrate overlaps with the orthographic projection of the first isolation layer between the isolation grooves on the substrate; a second isolation layer of a third preset thickness is retained between the second isolation structures; and laser annealing is performed on the photoelectric functional layer in the isolation groove using the second isolation layer of the third preset thickness as a protective layer to activate the doped ions in the photoelectric functional layer.

[0006] In some embodiments of the present invention, after laser annealing the optoelectronic functional layer in the isolation groove, it also includes: removing the second isolation layer between the second isolation structures; forming a third isolation layer between the second isolation structures, and making the third isolation layer and the first isolation layer form an isolation structure surrounding the optoelectronic functional layer.

[0007] In some embodiments of the present invention, the third preset thickness is in the range of 5 nm to 10 nm.

[0008] In some embodiments of the present invention, forming a photoelectric functional layer in the isolation groove includes: depositing a photoelectric functional layer on the substrate and filling the multiple isolation grooves with the photoelectric functional layer; flattening the photoelectric functional layer and exposing the photoelectric functional layer to the first isolation layer between the isolation grooves.

[0009] In some embodiments of the present invention, the first preset thickness ranges from 2 μm to 3 μm; and / or the second preset thickness ranges from 4 nm to 6 nm.

[0010] In a second aspect, the present invention discloses an image sensor, comprising: a substrate, the substrate comprising a substrate and a plurality of first isolation structures located on the substrate; the plurality of first isolation structures are arranged at intervals; a first isolation layer located on the substrate, the first isolation layer having a plurality of isolation grooves; a first isolation layer of a second preset thickness is retained at the bottom of the isolation grooves; the orthographic projection of the first isolation layer between the isolation grooves on the substrate overlaps with the orthographic projection of the first isolation structure on the substrate; a photoelectric functional layer located in the isolation grooves, the photoelectric functional layer being used to form a photodiode; the first isolation layer at the bottom of the isolation grooves being used to isolate the photoelectric functional layer from the substrate; the first isolation layer between the isolation grooves being used to isolate the photoelectric functional layers in adjacent isolation grooves.

[0011] In some embodiments of the present invention, the present invention further includes: a plurality of second isolation structures located on the side of the optoelectronic functional layer facing away from the substrate; the orthographic projection of the second isolation structure on the substrate overlaps with the orthographic projection of the first isolation layer between the isolation grooves on the substrate.

[0012] In some embodiments of the present invention, the present invention further includes: a third isolation layer located between the second isolation structures, wherein the third isolation layer and the first isolation layer constitute an isolation structure surrounding the photoelectric functional layer.

[0013] In some embodiments of the present invention, the second preset thickness is in the range of 4 nm to 6 nm.

[0014] The present invention discloses an image sensor and a method for manufacturing the same. A first isolation layer of a first preset thickness is formed on a substrate having a plurality of first isolation structures arranged at intervals, and the first isolation layer is etched to form a plurality of isolation grooves, and the first isolation layer of a second preset thickness is retained at the bottom of the isolation grooves. A photoelectric functional layer is formed in the isolation grooves, and the photoelectric functional layer is used to form a photodiode. The first isolation layer at the bottom of the isolation grooves is used to isolate the photoelectric functional layer from the substrate, and the first isolation layer between the isolation grooves is used to isolate the photoelectric functional layers in adjacent isolation grooves. Therefore, there is no need to use high-energy ion implantation to form the photodiode, thereby avoiding substrate surface damage and the resulting crosstalk problem between photodiodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the background technology, the drawings required for use in the embodiments of the present invention or the background technology will be described below.

[0016] Figure 1 Schematic diagram of the cross-sectional structure of a traditional back-illuminated image sensor.

[0017] Figure 2 The present invention discloses a flowchart of a method for manufacturing an image sensor.

[0018] Figures 3 to 16 Schematic diagram of the cross-sectional structure of an image sensor in various manufacturing steps disclosed in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention will be described below in conjunction with the accompanying drawings. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] like Figure 1As shown, in a conventional back-illuminated image sensor fabrication method, photodiodes 11 are formed by implanting second-type dopant ions, such as phosphorus ions, into a substrate 10 doped with first-type dopant ions, such as boron ions. Because photodiodes 11 need to be formed near the top surface of substrate 10, high-energy ions must be implanted from the bottom surface of substrate 10. However, high-energy ion implantation inevitably damages the bottom surface of substrate 10, leading to signal crosstalk between adjacent photodiodes 11.

[0021] Based on this, the present invention discloses a method for manufacturing a back-illuminated image sensor, which forms a photodiode by forming a photoelectric functional layer in an isolation trench, thereby eliminating the need for high-energy ion implantation to form the photodiode, thereby avoiding substrate surface damage and the resulting crosstalk problem between photodiodes.

[0022] As an optional implementation of the present disclosure, an embodiment of the present invention discloses a method for manufacturing an image sensor, which is a back-illuminated image sensor. Figure 2 As shown, Figure 2 This is a flow chart of a method for manufacturing an image sensor disclosed in an embodiment of the present invention. The method includes:

[0023] S101: providing a substrate, wherein the substrate comprises a substrate and a plurality of first isolation structures located in the substrate.

[0024] In some embodiments of the present invention, Figure 3 As shown, the substrate 10 can be etched to form a plurality of trenches, and then the plurality of trenches are filled with insulating materials to form a plurality of shallow trench isolation structures, which are the plurality of first isolation structures 12. Then, as shown in FIG. Figure 4 As shown, a circuit connection layer 13 is formed on the surface of the substrate 10 having the first isolation structure 12. Figure 5 As shown, the surface of the substrate 10 facing away from the circuit connection layer 13 is subjected to chemical mechanical polishing to thin the substrate 10. Figure 5 The substrate shown is the substrate provided by the embodiment of the present invention. Of course, the present invention is not limited to this. In other embodiments, the substrate 10 having the plurality of first isolation structures 12 and the circuit connection layer 13 can also be directly subjected to chemical mechanical polishing to obtain Figure 5 The substrate shown.

[0025] In some embodiments of the present invention, Figure 5As shown, the thickness of the thinned substrate 10 is equal to the thickness of the first isolation structures 12, that is, the thinned substrate 10 exposes multiple first isolation structures 12. However, the present invention is not limited to this. In other embodiments, the thickness of the thinned substrate 10 may be slightly greater than or less than the thickness of the first isolation structures 12, that is, the thinned substrate 10 may not expose the multiple first isolation structures 12 or may expose the tops of the multiple first isolation structures 12.

[0026] In the embodiment of the present invention, the substrate 10 can be formed of a semiconductor material, an insulating material, a conductive material, or a combination of at least two of these materials. For example, the substrate 10 can be formed of silicon, silicon germanium, silicon germanium carbon, silicon carbide, etc. The thickness of the substrate 10 can range from 2.5 μm to 3.5 μm, for example, 2.6 μm, 3 μm, or 3.3 μm.

[0027] In some embodiments of the present invention, the circuit connection layer 13 includes at least a first dielectric layer 131, a second dielectric layer 132, multiple gate structures 133 located within the first dielectric layer 131, multiple conductive connection structures 134 located within the second dielectric layer 132, and multiple pads 135 located on a side of the second dielectric layer 132 facing away from the substrate 10. Furthermore, the multiple pads 135 are electrically connected to the multiple gate structures 133 via the multiple conductive connection structures 134. The circuit connection layer 13 is used to conduct the electrical signals generated by the photodiode sensing light signals to a printed circuit board, etc. Of course, the present invention is not limited to this. In other embodiments, the circuit connection layer 13 may also include a driving transistor or a switching transistor, a capacitor, etc., which will not be further described here.

[0028] S102: forming a first isolation layer of a first preset thickness on a substrate, and etching the first isolation layer to form a plurality of isolation trenches, wherein the first isolation layer of a second preset thickness remains at the bottom of the isolation trenches.

[0029] In the embodiment of the present invention, Figure 5 After the substrate shown, as Figure 6 As shown, a first isolation layer 14 of a first preset thickness d1 is formed on the surface of the substrate 10 on the side away from the circuit connection layer 13. The first isolation layer 14 may include a silicon layer doped with B element, etc. The formation process of the first isolation layer 14 may include a selective epitaxial deposition process, etc. For example, a silicon layer doped with B element may be formed by selectively epitaxially growing a single crystal silicon layer on the substrate 10 and doping B element during the growth of the single crystal silicon layer. Then, as shown in FIG. Figure 7 As shown, the first isolation layer 14 is etched to form a plurality of isolation trenches 140, and the first isolation layer 14 with a second preset thickness d2 is retained at the bottom of the isolation trenches 140. The etching process of the first isolation layer 14 can be a wet etching process or a dry etching process.

[0030] The orthographic projection of the first isolation layer 14 between the isolation trenches 140 on the substrate 10 overlaps with the orthographic projection of the first isolation structure 12 on the substrate 10, so that the optoelectronic functional layer subsequently formed within the isolation trenches 140 can, after converting optical signals into electrical signals, transmit the electrical signals to the circuit connection layer 13 through the substrate 10 between the first isolation structures 12. The first preset thickness d1 can range from 2 μm to 3 μm; and / or the second preset thickness d2 can range from 4 nm to 6 nm. For example, the first preset thickness d1 is 2 μm, 2.5 μm, 2.8 μm, or 3 μm, and the second preset thickness d2 is 4 nm, 4.5 nm, 5 nm, 5.5 nm, or 6 nm, etc.

[0031] S103: forming a photoelectric functional layer in the isolation trench, so that the photoelectric functional layer forms a photodiode.

[0032] In some embodiments of the present invention, Figure 8 As shown, the photoelectric functional layer 15 can be first deposited on the substrate 10, and the photoelectric functional layer 15 fills the plurality of isolation grooves 140, and then, as shown in FIG. Figure 9 As shown, the photovoltaic functional layer 15 is planarized, for example, by chemical mechanical polishing, so that the photovoltaic functional layer 15 exposes the first isolation layer 14 between the isolation trenches 140. The first isolation layer 14 at the bottom of the isolation trenches 140 is used to isolate the photovoltaic functional layer 15 from the substrate 10, and the first isolation layer 14 between the isolation trenches 140 is used to isolate the photovoltaic functional layer 15 within adjacent isolation trenches 140. Of course, the present invention is not limited to this. In other embodiments, the photovoltaic functional layer 15 may not completely fill the plurality of isolation trenches 140, and then the photovoltaic functional layer 15 and the first isolation layer 14 between the isolation trenches 140 may be planarized together. This will not be described in detail here.

[0033] In an embodiment of the present invention, the material of the photovoltaic functional layer 15 includes at least an N-type dopant element and a P-type dopant element. The N-type dopant element includes a Group V element such as phosphorus (P) or arsenic (As), and the P-type dopant element includes a Group III element such as boron (B) or aluminum (Al). The process for forming the photovoltaic functional layer 15 may include a selective epitaxial deposition process, for example. Based on this, the photovoltaic functional layer 15 can convert optical signals into electrical signals based on the photoelectric effect. That is, the photovoltaic functional layer 15 can convert optical signals into electrical signals, thus realizing the function of a photodiode.

[0034] In some embodiments of the present invention, the photoelectric functional layer 15 may be a single-layer structure. For example, the material of the photoelectric functional layer 15 may be SiBP. However, the present invention is not limited thereto. In other embodiments, the photoelectric functional layer 15 may be a multilayer structure, with two adjacent layers having an N-type dopant element and a P-type dopant element, respectively. For example, the materials of two adjacent layers may be SiB and SiP, respectively. It should be noted that the content of the element B in the photoelectric functional layer 15 must be less than the content of the element P to improve the photoelectric performance of the photodiode.

[0035] Because the optoelectronic functional layer 15 deposited within the isolation trench 140 can form a photodiode, high-energy ion implantation is not required to form the photodiode, thereby avoiding surface damage to the substrate 10 and the resulting crosstalk between photodiodes. Furthermore, because the first isolation layer 14 at the bottom of the isolation trench 140 can isolate the optoelectronic functional layer 15 from the substrate 10, and the first isolation layer 14 between the isolation trenches 140 can isolate the optoelectronic functional layer 15 within adjacent isolation trenches 140, crosstalk between photodiodes can be further avoided.

[0036] In some embodiments of the present invention, after forming the photoelectric functional layer 15 in the isolation trench 140, as shown in FIG. Figure 10 As shown, a second isolation layer 16 may be formed on the side of the photoelectric functional layer 15 facing away from the substrate 10, and then, as shown in FIG. Figure 11 As shown, the second isolation layer 16 can be etched to form a plurality of second isolation structures 160. Among them, the second isolation layer 16 with a third preset thickness d3 is retained between the second isolation structures 160. Then, as shown in FIG. Figure 12 As shown, the second isolation layer 16 with a third preset thickness d3 can be used as a protective layer to perform laser annealing on the optoelectronic functional layer 15 in the isolation trench 140 to activate the doped ions in the optoelectronic functional layer 15 .

[0037] In some embodiments of the present invention, Figure 11 As shown, the second isolation layer 16 may include a first sub-isolating layer 161, a second sub-isolating layer 162, and a third sub-isolating layer 163. The material of the first sub-isolating layer 161 may be tantalum oxide, the material of the second sub-isolating layer 162 may be aluminum, and the material of the third sub-isolating layer 163 may be titanium nitride. The second isolation layer 16 of the third predetermined thickness d3 retained between the second isolation structures 160 is a portion of the first sub-isolating layer 161. Of course, the present invention is not limited to this. In other embodiments, the second isolation layer 16 may include two, four, or even more layers, which will not be further described here.

[0038] In some embodiments of the present invention, the width of the second isolation structure 160 gradually decreases in the direction away from the substrate 10 to increase the light flux between the second isolation structures 160, allowing more light to be received by the photovoltaic functional layer 15, increasing the number of electron-hole pairs in the photovoltaic functional layer 15, and reducing crosstalk between adjacent photodiodes, thereby improving the photoelectric effect of the photodiodes. Of course, the present invention is not limited to this. In other embodiments, the width of the second isolation structure 160 in the direction away from the substrate 10 can be equal, which will not be repeated here.

[0039] In some embodiments of the present invention, the third predetermined thickness d3 may be in a range of 5 nm to 10 nm, for example, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, or 10 nm. The orthographic projection of the second isolation structure 160 on the substrate 10 may overlap with the orthographic projection of the first isolation layer 14 between the isolation trenches 140 on the substrate 10, so that the second isolation structure 160 can isolate light interference from adjacent photodiodes.

[0040] It should be noted that laser annealing the optoelectronic functional layer 15 can activate doped ions, reduce dark current generation, enhance the optoelectronic performance of the photodiode, and improve the yield and imaging quality of the image sensor. The laser annealing can be performed in an oxygen-containing environment, and the laser energy can be 50 mJ to 150 mJ, for example, 50 mJ, 70 mJ, 100 mJ, 125 mJ, or 150 mJ.

[0041] In some embodiments of the present invention, Figure 13 As shown, after laser annealing the optoelectronic functional layer 15 within the isolation trench 140, the optoelectronic functional layer 15 located in the middle region of the isolation trench 140 is activated. However, due to the shielding of the second isolation structure 160, some areas surrounding the optoelectronic functional layer 15 are not activated. In other words, the optoelectronic functional layer 15 within the isolation trench 140 includes an activated region 150 and an inactivated region 151, and the inactivated region 151 includes a first interface layer 1511 and a second interface layer 1512. The first interface layer 1511 can be a silicon dioxide layer, and the second interface layer 1512 can be a silicon layer. Based on this, the photodiode within the isolation trench 140 can be a PIN photodiode.

[0042] In some embodiments of the present invention, after laser annealing is performed on the optoelectronic functional layer 15 in the isolation trench 140, Figure 14 As shown, the second isolation layer 16 between the second isolation structures 160 can also be removed to expose the optoelectronic functional layer 15 in the isolation trench 140. It is understood that when the second isolation layer 16 is etched, the first interface layer 1511 and the second interface layer 1512 on the top of the optoelectronic functional layer 15 can also be at least partially etched away. Figure 15As shown, a third isolation layer 17 is formed between the second isolation structures 160, and the third isolation layer 17 and the first isolation layer 14 form an isolation structure surrounding the photoelectric functional layer 15. Based on this, signal interference between adjacent photodiodes can be further reduced.

[0043] In some embodiments of the present invention, the material of the third isolation layer 17 is the same as that of the first isolation layer 14. For example, both the third isolation layer 17 and the first isolation layer 14 are silicon layers doped with element B. Of course, the present invention is not limited thereto. In other embodiments, the material of the third isolation layer 17 may be different from that of the first isolation layer 14.

[0044] Of course, the present invention is not limited to this. In other embodiments, Figure 9 After the structure shown is formed, laser annealing is performed on the optoelectronic functional layer 15 within the isolation trench 140. At this point, without the shielding of the second isolation structure 160, the optoelectronic functional layer 15 is substantially activated, and the photodiode within the isolation trench 140 is a PN photodiode. A third isolation layer 17 is then formed on the substrate 10, and the third isolation layer 17 and the first isolation layer 14 form an isolation structure surrounding the optoelectronic functional layer 15. A plurality of second isolation structures 160 are then formed on the substrate 10.

[0045] In other embodiments, the Figure 9 After the structure shown, a third isolation layer 17 is formed on the substrate 10, and the third isolation layer 17 and the first isolation layer 14 form an isolation structure surrounding the photovoltaic functional layer 15. Then, a second isolation layer 16 is formed on the side of the photovoltaic functional layer 15 facing away from the substrate 10. The second isolation layer 16 is etched to form a plurality of second isolation structures 160, and a second isolation layer 16 of a third predetermined thickness d3 is retained between the second isolation structures 160. Then, using the second isolation layer 16 of the third predetermined thickness d3 as a protective layer, the photovoltaic functional layer 15 in the isolation trench 140 is laser annealed.

[0046] In some embodiments of the present invention, Figure 16 As shown, a filter element 18 may be formed between adjacent second isolation structures 160. The filter element 18 may be a red filter element, a green filter element, or a blue filter element. The filter element 18 is configured to transmit some light and filter out other light. The filter element 18 may be made of a polymeric material, such as a negative photoresist based on an acrylic polymer.

[0047] In some embodiments of the present invention, Figure 16As shown, the top of the filter element 18 may be in a convex arc shape to focus the incident light on the optoelectronic functional layer 15. Of course, the present invention is not limited to this. In other embodiments, the surface curvature of the filter element 18 may also be changed according to the focusing requirements, which will not be described in detail here.

[0048] As an optional implementation of the present disclosure, an embodiment of the present disclosure discloses an image sensor, which is a back-illuminated image sensor. The image sensor can be manufactured using the manufacturing method disclosed in any of the above embodiments. Figure 9 As shown, the image sensor includes:

[0049] The substrate includes a substrate 10 and a plurality of first isolation structures 12 located on the substrate 10. The plurality of first isolation structures 12 are arranged at intervals. The substrate also includes a circuit connection layer 13 located on the side of the substrate 10 having the first isolation structure 12. In some embodiments of the present invention, the circuit connection layer 13 includes at least a first dielectric layer 131, a second dielectric layer 132, a plurality of gate structures 133 located in the first dielectric layer 131, a plurality of conductive connection structures 134 located in the second dielectric layer 132, and a plurality of pads 135 located on the side of the second dielectric layer 132 away from the substrate 10, and the plurality of pads 135 are electrically connected to the plurality of gate structures 133 through the plurality of conductive connection structures 134. The circuit connection layer 13 is used to lead the electrical signal generated by the photodiode sensing light signal to a printed circuit board, etc. Of course, the present invention is not limited to this. In other embodiments, the circuit connection layer 13 may also include a driving transistor or a switching transistor and a capacitor, etc., which will not be repeated here.

[0050] A first isolation layer 14 is located on the substrate 10, and the first isolation layer 14 has a plurality of isolation grooves 140. A first isolation layer 14 of a second preset thickness is retained at the bottom of the isolation grooves 140. The second preset thickness d2 can range from 4 nm to 6 nm. For example, the second preset thickness d2 is 4 nm, 4.5 nm, 5 nm, 5.5 nm, or 6 nm. The orthographic projection of the first isolation layer 14 between the isolation grooves 140 on the substrate 10 overlaps with the orthographic projection of the first isolation structure 12 on the substrate 10, so that the optoelectronic functional layer subsequently formed in the isolation grooves 140 can convert the optical signal into an electrical signal and transmit the electrical signal to the circuit connection layer 13 through the substrate 10 between the first isolation structures 12.

[0051] The photoelectric functional layer 15 located within the isolation trenches is used to form a photodiode. The first isolation layer 14 at the bottom of the isolation trenches 140 is used to isolate the photoelectric functional layer 15 from the substrate 10 , and the first isolation layer 14 between the isolation trenches 140 is used to isolate the photoelectric functional layers 15 within adjacent isolation trenches 140 .

[0052] Because the optoelectronic functional layer 15 deposited within the isolation trench 140 can form a photodiode, high-energy ion implantation is not required to form the photodiode, thereby avoiding surface damage to the substrate 10 and the resulting crosstalk between photodiodes. Furthermore, because the first isolation layer 14 at the bottom of the isolation trench 140 can isolate the optoelectronic functional layer 15 from the substrate 10, and the first isolation layer 14 between the isolation trenches 140 can isolate the optoelectronic functional layer 15 within adjacent isolation trenches 140, crosstalk between photodiodes can be further avoided.

[0053] In some embodiments of the present invention, Figure 13 As shown, the photoelectric functional layer 15 in the isolation trench 140 includes an active region 150 and an inactive region 151, and the inactive region 151 includes a first interface layer 1511 and a second interface layer 1512. The first interface layer 1511 may be a silicon dioxide layer, and the second interface layer 1512 may be a silicon layer.

[0054] In some embodiments of the present invention, Figure 15 As shown, the image sensor further includes: a plurality of second isolation structures 160 located on the side of the optoelectronic functional layer 15 facing away from the substrate 10. The orthographic projections of the second isolation structures 160 on the substrate 10 overlap with the orthographic projections of the first isolation layer 14 between the isolation trenches 140 on the substrate 10. The plurality of second isolation structures 160 are formed by etching from the second isolation layer 16.

[0055] In some embodiments of the present invention, Figure 11 As shown, the second isolation layer 16 may include a first sub-isolating layer 161, a second sub-isolating layer 162, and a third sub-isolating layer 163. The material of the first sub-isolating layer 161 may be tantalum oxide, the material of the second sub-isolating layer 162 may be aluminum, and the material of the third sub-isolating layer 163 may be titanium nitride. The second isolation layer 16 of the third predetermined thickness d3 retained between the second isolation structures 160 is a portion of the first sub-isolating layer 161. Of course, the present invention is not limited to this. In other embodiments, the second isolation layer 16 may include two, four, or even more layers, which will not be further described here.

[0056] In some embodiments of the present invention, the width of the second isolation structure 160 gradually decreases in the direction away from the substrate 10 to increase the light flux between the second isolation structures 160, allowing more light to be received by the photovoltaic functional layer 15, increasing the number of electron-hole pairs in the photovoltaic functional layer 15, and reducing crosstalk between adjacent photodiodes, thereby improving the photoelectric effect of the photodiodes. Of course, the present invention is not limited to this. In other embodiments, the width of the second isolation structure 160 in the direction away from the substrate 10 can be equal, which will not be repeated here.

[0057] In some embodiments of the present invention, Figure 15 As shown, the image sensor further includes: a third isolation layer 17 located between the second isolation structures 160 , and the third isolation layer 17 and the first isolation layer 14 form an isolation structure surrounding the optoelectronic functional layer 15 .

[0058] In some embodiments of the present invention, the material of the third isolation layer 17 is the same as that of the first isolation layer 14. For example, both the third isolation layer 17 and the first isolation layer 14 are silicon layers doped with element B. Of course, the present invention is not limited thereto. In other embodiments, the material of the third isolation layer 17 may be different from that of the first isolation layer 14.

[0059] In some embodiments of the present invention, Figure 16 As shown, the image sensor further includes a filter element 18 located between the second isolation structures 160. The filter element 18 can be a red filter element, a green filter element, or a blue filter element, etc. The filter element 18 is used to transmit part of the light and filter out other light.

[0060] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above 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.

[0061] The above embodiments merely represent several implementation methods of this specification. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the scope of this specification, and these modifications and improvements fall within the scope of protection of this specification. Therefore, the scope of protection of the patent in this specification shall be subject to the appended claims.

Claims

1. A method for manufacturing an image sensor, characterized in that: include: Providing a substrate, the substrate comprising a substrate and a plurality of first isolation structures located in the substrate; The plurality of first isolation structures are arranged at intervals; forming a first isolation layer of a first preset thickness on the substrate, and etching the first isolation layer to form a plurality of isolation grooves; A first isolation layer of a second preset thickness is retained at the bottom of the isolation trench; the orthographic projection of the first isolation layer between the isolation trenches on the substrate overlaps with the orthographic projection of the first isolation structure on the substrate; forming a photoelectric functional layer in the isolation trench so that the photoelectric functional layer forms a photodiode; The first isolation layer at the bottom of the isolation trench is used to isolate the photoelectric functional layer from the substrate; the first isolation layer between the isolation trenches is used to isolate the photoelectric functional layers in adjacent isolation trenches.

2. The method for manufacturing an image sensor according to claim 1, wherein: After forming the photoelectric functional layer in the isolation trench, the method further includes: forming a second isolation layer on a side of the photoelectric functional layer facing away from the substrate, and etching the second isolation layer to form a plurality of second isolation structures; the orthographic projections of the second isolation structures on the substrate overlap with the orthographic projections of the first isolation layer between the isolation trenches on the substrate; and retaining a second isolation layer of a third predetermined thickness between the second isolation structures; The second isolation layer with the third preset thickness is used as a protective layer, and laser annealing is performed on the photoelectric functional layer in the isolation groove to activate the photoelectric functional layer.

3. The method for manufacturing an image sensor according to claim 2, wherein: After the photoelectric functional layer in the isolation trench is laser annealed, the method further comprises: removing the second isolation layer between the second isolation structures; A third isolation layer is formed between the second isolation structures, and the third isolation layer and the first isolation layer constitute an isolation structure surrounding the photoelectric functional layer.

4. The method for manufacturing an image sensor according to claim 2, wherein: The third preset thickness ranges from 5 nm to 10 nm.

5. The method for manufacturing an image sensor according to claim 1, wherein: The forming of the photoelectric functional layer in the isolation trench comprises: Depositing a photoelectric functional layer on the substrate, and making the photoelectric functional layer fill the plurality of isolation grooves; The photoelectric functional layer is planarized so as to expose the first isolation layer between the isolation grooves through the photoelectric functional layer.

6. The method for manufacturing an image sensor according to claim 1, wherein: The first preset thickness ranges from 2 μm to 3 μm; and / or the second preset thickness ranges from 4 nm to 6 nm.

7. An image sensor, characterized in that: include: a substrate, comprising a substrate and a plurality of first isolation structures located on the substrate; The plurality of first isolation structures are arranged at intervals; a first isolation layer located on the substrate, the first isolation layer having a plurality of isolation trenches; a first isolation layer of a second predetermined thickness remaining at the bottom of the isolation trenches; an orthographic projection of the first isolation layer between the isolation trenches on the substrate overlapping with an orthographic projection of the first isolation structure on the substrate; The photoelectric functional layer is located in the isolation groove, and the photoelectric functional layer includes an activated area and an inactivated area. The photoelectric functional layer in the inactivated area is located between the first isolation layer and the photoelectric functional layer in the activated area, and the photoelectric functional layer in the inactivated area is partially arranged around the photoelectric functional layer in the activated area. The photoelectric functional layer in the inactivated area and the photoelectric functional layer in the activated area are used to form a photodiode; the first isolation layer at the bottom of the isolation groove is used to isolate the photoelectric functional layer from the substrate; the first isolation layer between the isolation grooves is used to isolate the photoelectric functional layers in adjacent isolation grooves.

8. The image sensor according to claim 7, wherein: Also includes: a plurality of second isolation structures located on a side of the photoelectric functional layer facing away from the substrate; An orthographic projection of the second isolation structure on the substrate overlaps with an orthographic projection of the first isolation layer between the isolation trenches on the substrate.

9. The image sensor according to claim 8, wherein: Also includes: A third isolation layer is located between the second isolation structures, and the third isolation layer and the first isolation layer form an isolation structure surrounding the photoelectric functional layer.

10. The image sensor according to claim 7, wherein: The second preset thickness ranges from 4 nm to 6 nm.

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