Optical sensor and method of forming the same, and electronic device

Abstract

The application discloses an optoelectronic sensor and a forming method thereof, and an electronic device. The forming method comprises the following steps: providing a substrate, wherein the substrate comprises a pixel region, and the pixel region comprises a plurality of array-arranged sub-pixel regions; forming a plurality of first light traps on the substrate surface of the sub-pixel region, wherein in the sub-pixel region, the plurality of first light traps are arranged along the diagonal direction of the grid, and are arranged with intervals between the first light traps along the row direction and the column direction of the grid, and a preset region is formed between the adjacent first light traps along the row direction and the adjacent first light traps along the column direction; forming a filling layer filled in the first light traps; forming a second light trap in the preset region exposed by the filling layer, and the second light trap and the first light trap form a grid-arranged light trap. The embodiment of the application is beneficial to improving the performance of the optoelectronic sensor and reducing the process risk.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing, and more particularly to a photoelectric sensor and a method for forming the same, as well as an electronic device. Background Technology

[0002] A photoelectric sensor is a device that converts light signals into electrical signals. Its working principle is based on the photoelectric effect, which refers to the phenomenon where electrons in a substance absorb the energy of photons and produce corresponding electrical effects when light shines on them.

[0003] For example, CCD (Charge Coupled Device) image sensors and CMOS image sensors utilize photoelectric conversion to convert optical images into electrical signals and output digital images. They are currently widely used in digital cameras and other electro-optical devices. ToF (Time of Flight) distance sensors project modulated infrared light onto objects, people, or scenes, and the reflected light is captured by the ToF sensor. This sensor measures the light intensity and phase difference received by each pixel, thereby obtaining highly reliable depth images and grayscale images of the entire scene. This technology can be used in various ranging scenarios such as autonomous driving, robotic vacuum cleaners, and VR (Virtual Reality) / AR (Augmented Reality) modeling.

[0004] Photoelectric sensors all have a pixel area of ​​a certain size to receive optical signals. The higher the optical transmittance of the pixel area, the better the optical sensitivity performance of the device.

[0005] However, the performance of current photoelectric sensors still needs to be improved. Summary of the Invention

[0006] The problem addressed by the embodiments of the present invention is to provide a photoelectric sensor, a method for forming the same, and an electronic device, thereby improving the performance of the photoelectric sensor and reducing process risks.

[0007] To address the aforementioned problems, embodiments of the present invention provide a photoelectric sensor, comprising: a substrate; the substrate including a pixel region, the pixel region including a plurality of sub-pixel regions arranged in an array; a plurality of first light-trapping grooves located on the substrate surface of the sub-pixel regions, wherein in the sub-pixel regions, the plurality of first light-trapping grooves are arranged along a grid-like diagonal direction, and along the row and column directions of the grid, the first light-trapping grooves are spaced apart, and adjacent first light-trapping grooves along the row direction and adjacent first light-trapping grooves along the column direction form a preset region; a plurality of second light-trapping grooves located within the substrate of the preset region, and the second light-trapping grooves and the first light-trapping grooves constitute a grid-like arrangement of light-trapping grooves.

[0008] Optionally, the first light trapping groove and the second light trapping groove are seamlessly connected.

[0009] Optionally, the photoelectric sensor further includes a filling layer, which is filled in the first light trapping groove.

[0010] Optionally, the material of the filling layer includes silicon oxide, silicon nitride, silicon oxynitride, or silicon carbide.

[0011] Optionally, the light trapping groove is an inverted pyramid structure.

[0012] Accordingly, embodiments of the present invention also provide a method for forming a photoelectric sensor, comprising: providing a substrate; the substrate including a pixel region, the pixel region including a plurality of sub-pixel regions arranged in an array; forming a plurality of photosensitive units in the substrate, the area where the photosensitive units are located being a sub-pixel region; forming a plurality of first light-trapping grooves on the substrate surface of the sub-pixel region, wherein in the sub-pixel region, the plurality of first light-trapping grooves are arranged along a grid-like diagonal direction, and along the row and column directions of the grid, the first light-trapping grooves are spaced apart, and adjacent first light-trapping grooves along the row direction and adjacent first light-trapping grooves along the column direction form a preset region; forming a filling layer filling the first light-trapping grooves; forming a second light-trapping groove in the preset region exposed in the filling layer, the second light-trapping groove and the first light-trapping grooves constituting a grid-like arrangement of light-trapping grooves.

[0013] Optionally, during the formation of the second light trapping groove, the second light trapping groove is seamlessly connected to the first light trapping groove.

[0014] Optionally, the step of forming the first light trapping groove includes: forming a hard mask layer on the substrate, wherein a plurality of mask openings are formed in the hard mask layer, the plurality of mask openings are arranged along the diagonal of the grid in the sub-pixel area, and along the row and column directions of the grid, the mask openings are spaced apart; using the hard mask layer as a mask, etching the substrate exposed by the mask openings to form the first light trapping groove.

[0015] Optionally, the method for forming the photoelectric sensor further includes: removing the hard mask layer after forming the first light trapping groove and before forming the filling layer; or, removing the hard mask layer during the step of forming the filling layer.

[0016] Optionally, the step of forming the filling layer includes: forming a filling material layer in the first light trapping groove, the filling material layer also being formed on the substrate on the side of the first light trapping groove; removing the filling material layer on the substrate on the side of the first light trapping groove, and using the remaining filling material layer in the first light trapping groove as the filling layer.

[0017] Optionally, the process for forming the filling material layer includes one or both of chemical vapor deposition and atomic layer deposition.

[0018] Optionally, the process for forming the first light trapping groove includes a wet etching process.

[0019] Optionally, the process for forming the second light trapping groove includes a wet etching process.

[0020] Optionally, the etching solution in the wet etching process includes a TMAH solution.

[0021] Optionally, the method for forming the photoelectric sensor further includes removing the filling layer after forming the second light trapping groove.

[0022] Optionally, the process for removing the filler layer includes a wet etching process.

[0023] Accordingly, embodiments of the present invention also provide an electronic device, including: a photoelectric sensor provided in embodiments of the present invention.

[0024] Compared with the prior art, the technical solution of the embodiments of the present invention has the following advantages:

[0025] In the photoelectric sensor provided in this embodiment of the invention, in the sub-pixel region, a plurality of first light-trapping grooves are arranged along a grid-like diagonal direction, and along the row and column directions of the grid, the first light-trapping grooves are spaced apart, and adjacent first light-trapping grooves along the row direction and adjacent first light-trapping grooves along the column direction form a preset region; a plurality of second light-trapping grooves are located within the substrate of the preset region, and the second light-trapping grooves and the first light-trapping grooves constitute a grid-like arrangement of light-trapping grooves. Accordingly, during the formation process of the photoelectric sensor, the preset region formed between adjacent first light-trapping grooves defines the formation position of the second light-trapping grooves. In the step of forming the second light-trapping groove, the first light-trapping groove is usually also filled with a filling layer. Accordingly, the filling layer can be used as a mask to expose the light-trapping groove in the sub-pixel region. In this embodiment of the invention, a second light trapping groove is formed within a preset area. Compared with the scheme in the same step, where a hard mask layer located on the substrate is used as a mask to form a grid-like arrangement of light trapping grooves in the sub-pixel area, the filling layer is filled within the first light trapping groove. This helps to avoid the problem of the hard mask layer (or filling layer) losing support and falling down due to the small platform area between adjacent first and second light trapping grooves. This reduces process risks. Furthermore, it also helps to make the size of the platform area between the first and second light trapping grooves smaller, or to make adjacent first and second light trapping grooves seamlessly connected. This increases the density of the light trapping grooves, reduces light reflectivity, and improves optical transmittance, thereby enhancing the performance of the photoelectric sensor.

[0026] In the photoelectric sensor formation method provided by this invention, a plurality of first light-trapping grooves are formed on the substrate surface of the sub-pixel region. In the sub-pixel region, the plurality of first light-trapping grooves are arranged along a grid-like diagonal direction, and along the row and column directions of the grid, the first light-trapping grooves are spaced apart, and adjacent first light-trapping grooves along the row direction and adjacent first light-trapping grooves along the column direction form a preset region. Then, a filling layer is formed within the first light-trapping grooves. Correspondingly, in the step of forming the second light-trapping groove, the filling layer within the first light-trapping groove can be used as a mask to form the second light-trapping groove within the preset region exposed by the filling layer. The first and second light-trapping grooves constitute a grid-like arrangement of light-trapping grooves, and are formed in the same step... Compared to the scheme of forming a grid-like arrangement of light traps in the sub-pixel area using a hard mask layer located on the substrate as a mask, the embodiment of the present invention, in the process of forming the second light trap, since the filling layer is filled in the first light trap, helps to avoid the problem of the hard mask layer (or filling layer) losing support and falling down due to the small platform area between adjacent first and second light traps. This is beneficial to reducing process risks. Moreover, it is also beneficial to make the size of the platform area between the first and second light traps smaller, or to make the adjacent first and second light traps seamlessly connected, thereby increasing the density of light traps, reducing light reflectivity, and correspondingly improving optical transmittance, thus improving the performance of the photoelectric sensor. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of a photoelectric sensor;

[0028] Figure 2 This is a schematic diagram of the structure corresponding to the step of forming a light trapping groove;

[0029] Figures 3 to 5 This is a schematic diagram of the structure of an embodiment of the photoelectric sensor of the present invention;

[0030] Figures 6 to 7 This is a schematic diagram of another embodiment of the photoelectric sensor of the present invention;

[0031] Figures 8 to 29 This is a schematic diagram of the structure corresponding to each step in one embodiment of the method for forming the photoelectric sensor of the present invention. Detailed Implementation

[0032] As the background technology shows, the performance of current photoelectric sensors needs improvement. This paper will now discuss one reason why the performance of current photoelectric sensors needs further improvement. Figure 1 This is a schematic diagram of the structure of a photoelectric sensor.

[0033] like Figure 1As shown, the photoelectric sensor includes: a substrate 10 having a first surface 11; the substrate 10 includes a pixel region, the pixel region including a plurality of sub-pixel regions 10a arranged in an array; and light trapping grooves 12 located in the sub-pixel regions 10a of the first surface 11, wherein adjacent light trapping grooves 12 in the sub-pixel regions 10a have a plateau region (e.g., ...). Figure 1 (The location indicated by the middle arrow A).

[0034] In the photoelectric sensor, there is also a platform region between adjacent light trapping grooves 12. The larger the size of the platform region, the higher the light reflectivity, the lower the optical transmittance of the photoelectric sensor, and the performance of the photoelectric sensor needs to be improved.

[0035] like Figure 2 The diagram shows a structural schematic corresponding to the step of forming a light trapping groove. Specifically, a hard mask layer 13 is formed on the first surface 11 of the substrate 10, and a plurality of mask openings 14 are formed in the hard mask layer 13; using the hard mask layer 13 as a mask, the substrate 10 exposed by the mask openings 14 is etched to form a light trapping groove 12.

[0036] One approach is to increase the etching time of the substrate 10 during the formation of the light trapping groove 12, thereby reducing the size of the plateau region between adjacent light trapping grooves 12. However, as... Figure 2 The dotted lines in the diagram indicate that the light-trapping grooves reduce the size of the platform area, which can easily lead to the hard mask layer 13 losing support and collapsing, resulting in a high process risk. In particular, in the semiconductor field, wet etching is commonly used to etch the substrate 10 exposed by the mask opening 14 to form the light-trapping grooves 12. If the hard mask layer 13 loses support, it is easy to collapse and fall into the etching solution, which can easily contaminate the etching solution. After using the etching solution to etch subsequent products, the risk of particle defects in the subsequent products is high.

[0037] To address the aforementioned technical problem, this invention provides a photoelectric sensor. In the sub-pixel region, a plurality of first light-trapping grooves are arranged along a grid-like diagonal direction, and are spaced apart along the row and column directions of the grid. Adjacent first light-trapping grooves along the row direction and adjacent first light-trapping grooves along the column direction form a preset region. A plurality of second light-trapping grooves are located within the substrate of the preset region, and the second and first light-trapping grooves constitute a grid-like arrangement of light-trapping grooves. Accordingly, during the formation of the photoelectric sensor, the preset region formed between adjacent first light-trapping grooves defines the formation position of the second light-trapping grooves. In the step of forming the second light-trapping groove, the first light-trapping groove is typically filled with a filling layer. Accordingly, the filling layer can be used as a mask to form the filling layer. A second light trap is formed within the preset area exposed by the layer. Compared with the scheme of forming a grid-like arrangement of light traps in the sub-pixel area using a hard mask layer located on the substrate as a mask in the same step, in this embodiment of the invention, since the filling layer is filled in the first light trap, it is beneficial to avoid the problem that the hard mask layer (or filling layer) will lose support and fall down due to the small platform area between adjacent first and second light traps. This is beneficial to reduce process risks. Moreover, it is also beneficial to make the size of the platform area between the first and second light traps smaller, or to make the adjacent first and second light traps seamlessly connected, thereby increasing the density of light traps, reducing light reflectivity, and correspondingly improving optical transmittance, thus improving the performance of the photoelectric sensor.

[0038] To address the aforementioned technical problem, this invention also provides a method for forming a photoelectric sensor. A plurality of first light-trapping grooves are formed on the substrate surface of a sub-pixel region. In the sub-pixel region, the plurality of first light-trapping grooves are arranged along a grid-like diagonal direction, and along the row and column directions of the grid. The first light-trapping grooves are spaced apart, and adjacent first light-trapping grooves along the row direction and adjacent first light-trapping grooves along the column direction form a preset region. Then, a filling layer is formed within the first light-trapping grooves. Correspondingly, in the step of forming the second light-trapping groove, the filling layer within the first light-trapping groove can be used as a mask to form the second light-trapping groove within the preset region exposed by the filling layer. The first and second light-trapping grooves constitute a grid-like arrangement of light-trapping grooves. Compared to the scheme of forming a grid-like arrangement of light traps in the sub-pixel area using a hard mask layer located on the substrate as a mask in the same step, the embodiment of the present invention, in the process of forming the second light trap, since the filling layer is filled in the first light trap, helps to avoid the problem of the hard mask layer (or filling layer) losing support and falling down due to the small platform area between adjacent first and second light traps. This is beneficial to reduce process risks. Moreover, it is also beneficial to make the size of the platform area between the first and second light traps smaller, or to make the adjacent first and second light traps seamlessly connected, thereby increasing the density of light traps, reducing light reflectivity, and correspondingly improving optical transmittance, thus improving the performance of the photoelectric sensor.

[0039] To make the above-mentioned objects, features and advantages of the embodiments of the present invention more apparent and understandable, the specific embodiments of the photoelectric sensor of the present invention will be described in detail below with reference to the accompanying drawings.

[0040] refer to Figures 3 to 5 , Figure 3 (a) is a top view. Figure 3 (b) is Figure 3 (a) A magnified view of a portion of pixel P. Figure 4 This is a top view of sub-pixel area 100a. Figure 5 yes Figure 4 A partial cross-sectional view along secant line 1-1' shows a schematic diagram of the structure of an embodiment of the photoelectric sensor of the present invention.

[0041] As an example, this embodiment uses a TOF (Time of Flight) sensor as the photoelectric sensor for illustration. More specifically, the photoelectric sensor can be a DTOF (Direct Time of Flight) sensor.

[0042] In other embodiments, the photoelectric sensor may also be a CCD (Charge Coupled Device) image sensor, a CMOS image sensor, or an iTOF (indirect time of flight) sensor, or other types of photoelectric sensors.

[0043] In this embodiment, the photoelectric sensor includes: a substrate 100, the substrate 100 including a pixel region P, the pixel region P including a plurality of sub-pixel regions 100a arranged in an array; and a plurality of first light-trapping grooves 130 located on the surface of the substrate 100 of the sub-pixel regions 100a. In the sub-pixel regions 100a, the plurality of first light-trapping grooves 130 are arranged along a grid-like diagonal direction and along the row direction of the grid (e.g., ...). Figure 4 (as shown in the X direction) and column direction (as shown in the X direction) Figure 4 (As shown in the Y direction), the first light trapping grooves 130 are arranged at intervals, and adjacent first light trapping grooves 130 along the row direction and adjacent first light trapping grooves 130 along the column direction form a preset area; a plurality of second light trapping grooves 140 are located within the base 100 of the preset area, and the second light trapping grooves 140 and the first light trapping grooves 130 constitute a grid-like arrangement of light trapping grooves 200.

[0044] The substrate 100 is used to provide a process platform for the formation of photoelectric sensors.

[0045] In this embodiment, the substrate 100 has a first surface 101.

[0046] In this embodiment, the substrate 100 includes a substrate (not shown). Specifically, the substrate may be a silicon substrate. In other embodiments, the substrate material may also be germanium, silicon germanide, silicon carbide, gallium arsenide, or indium gallium ionide, etc., and the substrate may also be a silicon-on-insulator substrate or a germanium-on-insulator substrate, etc.

[0047] The pixel region P is used to receive optical signals so that the optical signals can be converted into electrical signals.

[0048] In the substrate 100, there are multiple pixel regions P, which are arranged in a matrix. The sub-pixel regions 100a are used to form pixels.

[0049] The first light trapping groove 130 is beneficial to improving the optical transmittance of the pixel area P, increasing the photoelectric conversion efficiency, and thus improving the optical sensitivity performance of the photoelectric sensor.

[0050] In this embodiment, a plurality of first light trapping grooves 130 are located in the sub-pixel region 100a of the first surface 101.

[0051] Specifically, the first light trapping groove 130 is disposed above the photoelectric element, which can slow down the change in refractive index between the air and the first surface 101, reduce the high reflectivity caused by the sudden change in refractive index at the interface, so that more light can enter the photoelectric element and improve the transmittance of incident light. Furthermore, by disposing the first light trapping groove 130 in the sub-pixel area 100a of the first surface 101, it is also beneficial to disperse the incident light to multiple angles, increase the effective optical path of the light, and thus play a role in trapping light.

[0052] During the formation of the photoelectric sensor, the first light trapping groove 130 is also used to provide a spatial position for the filling layer so that the filling layer can serve as an etching mask for forming the second light trapping groove 140.

[0053] A preset region D is formed between adjacent first light trapping slots 130 along the row direction and adjacent first light trapping slots 130 along the column direction. The preset region D is used to form a second light trapping slot 140.

[0054] As an example, the first light trap 130 is an inverted pyramid structure.

[0055] By framing the first light-trapping groove 130 as an inverted pyramid structure, a gradual change in refractive index is created between the air and the first surface 101. This increases the number of reflections of light within the inverted pyramid structure, effectively reducing light reflectivity and allowing more light to enter the optoelectronic element, thus improving optical transmittance. Simultaneously, as incident light passes through the inverted pyramid structure of the first surface 101, it is dispersed at various angles through reflection, scattering, and refraction, increasing the effective optical path and thus trapping light, thereby improving the absorption efficiency of light in the optoelectronic element.

[0056] The second light trap 140 helps to improve the optical transmittance of the pixel area P, increase the photoelectric conversion efficiency, and thus improve the optical sensitivity performance of the photoelectric sensor.

[0057] During the formation of the photoelectric sensor, the first light-trapping groove 130 is also used to provide spatial location for the filling layer, which serves as an etching mask for forming the second light-trapping groove 140. Accordingly, in the step of forming the second light-trapping groove 140, the filling layer filled in the first light-trapping groove 130 can be used as a mask to form the second light-trapping groove 140 in the preset area D exposed by the filling layer. The first light-trapping groove 130 and the second light-trapping groove 140 constitute a grid-like arrangement of light-trapping grooves 200. Since the filling layer is filled in the first light-trapping groove 130, This helps to avoid the problem of the hard mask layer (or filling layer) falling and collapsing due to the platform area between adjacent first and second light traps being too small, which reduces process risks. Moreover, it also helps to make the size of the platform area between the first light trap 130 and the second light trap 140 smaller, or to make the adjacent first light trap 130 and the second light trap 140 seamlessly connected, thereby increasing the density of the light trap 200, reducing the light reflectivity, and thus improving the optical transmittance and the performance of the photoelectric sensor.

[0058] As an example, the second light trap 140 is also an inverted pyramid structure.

[0059] By framing the first light-trapping groove 130 as an inverted pyramid structure, a gradual change in refractive index is created between the air and the first surface 101. This increases the number of reflections of light within the inverted pyramid structure, effectively reducing light reflectivity and allowing more light to enter the optoelectronic element, thus improving optical transmittance. Simultaneously, as incident light passes through the inverted pyramid structure of the first surface 101, it is dispersed at various angles through reflection, scattering, and refraction, increasing the effective optical path and thus trapping light, thereby improving the absorption efficiency of light in the optoelectronic element.

[0060] In this embodiment, the second light trapping groove 140 is seamlessly connected to the first light trapping groove 130.

[0061] In this embodiment, the seamless connection between the second light trapping groove 140 and the first light trapping groove 130 means that there is no platform area between the second light trapping groove 140 and the first light trapping groove 130. In other words, the size of the platform area between the second light trapping groove 140 and the first light trapping groove 130 is zero.

[0062] The seamless connection between the second light trapping groove 140 and the first light trapping groove 130 helps to further reduce the reflectivity of light in the pixel area, thereby improving the optical transmittance and thus enhancing the performance of the photoelectric sensor.

[0063] refer to Figures 6 to 7, Figure 6 This is a top view. Figure 7 yes Figure 6 A partial cross-sectional view along secant line 1-1' shows a schematic diagram of another embodiment of the photoelectric sensor of the present invention.

[0064] The similarities between this embodiment and the previous embodiment will not be repeated here. The difference between this embodiment and the previous embodiment is that the photoelectric sensor further includes a filling layer 260, which is filled in the first light trapping groove 230.

[0065] The filling layer 260 serves as a substrate 105 for etching the preset region D to form a mask for the second light trap 240.

[0066] Specifically, in the process of forming the photoelectric sensor, after forming the first light trapping groove 230, a filling layer 260 is formed in the first light trapping groove 230, and then a second light trapping groove 240 is formed in the preset area D exposed by the filling layer 260, using the filling layer 260 as a mask.

[0067] The filling layer 260 fills the first light trapping groove 230. Compared with the scheme of forming a grid-like arrangement of light trapping grooves in the sub-pixel area using a hard mask layer located on the first surface as a mask in the same step, the formation step of the second light trapping groove 240 is beneficial to avoid the problem of losing support and falling down due to the platform area between adjacent first light trapping grooves 230 and second light trapping grooves 260 being too small. This is beneficial to reduce process risks.

[0068] Moreover, after the second light trapping groove 260 is formed, the filling layer 260 is retained in the photoelectric sensor. The filling layer 260 can be used as a light-transmitting layer, which also eliminates the step of removing the filling layer 260, thus improving the process integration.

[0069] Specifically, in this embodiment, the filling layer 260 is made of an insulating dielectric material to avoid affecting the electrical performance of the photoelectric sensor. Furthermore, the filling layer 260 is also made of a light-transmitting material to ensure normal light transmission in the pixel area. In addition, the material of the filling layer 260 has etching selectivity with the material of the substrate 105 to ensure the etching masking effect of the filling layer 260 during the formation of the second light-trapping groove 240. As an example, the material of the filling layer 260 includes silicon oxide, silicon nitride, silicon oxynitride, or silicon carbide.

[0070] Accordingly, the present invention also provides a method for forming a photoelectric sensor. Figures 8 to 29 This is a schematic diagram of the structure corresponding to each step in one embodiment of the method for forming the photoelectric sensor of the present invention.

[0071] As an example, this embodiment uses a TOF (Time of Flight) sensor as the photoelectric sensor for illustration. More specifically, the photoelectric sensor can be a DTOF (Direct Time of Flight) sensor.

[0072] In other embodiments, the photoelectric sensor may also be a CCD (Charge Coupled Device) image sensor, a CMOS image sensor, or an iTOF (indirect time of flight) sensor, or other types of photoelectric sensors.

[0073] The method for forming the photoelectric sensor in this embodiment will be described in detail below with reference to the accompanying drawings.

[0074] refer to Figures 8 to 9 , Figure 8 (a) is a top view. Figure 8 (b) is Figure 8 (a) A magnified view of a portion of pixel P. Figure 9 The diagram shows a partial cross-sectional view of a sub-pixel region 100a. A substrate 100 is provided, having a first surface 101. The substrate 100 includes a pixel region P, which includes a plurality of sub-pixel regions 100a arranged in an array. A plurality of photosensitive units (not shown) are formed in the substrate 100, and the area where the photosensitive units are located is the sub-pixel region 100a.

[0075] The substrate 100 is used to provide a process platform for subsequent process manufacturing.

[0076] In this embodiment, the substrate 100 includes a substrate (not shown). Specifically, the substrate may be a silicon substrate. In other embodiments, the substrate material may also be germanium, silicon germanide, silicon carbide, gallium arsenide, or indium gallium ionide, etc., and the substrate may also be a silicon-on-insulator substrate or a germanium-on-insulator substrate, etc.

[0077] The pixel region P is used to receive optical signals so that the optical signals can be converted into electrical signals.

[0078] In the substrate 100, there are multiple pixel regions P, which are arranged in a matrix. The sub-pixel regions 100a are used to form pixels.

[0079] refer to Figures 10 to 19 A plurality of first light-trapping grooves 130 are formed on the surface of the substrate 100 in the sub-pixel region 100a. In the sub-pixel region 100a, the plurality of first light-trapping grooves 130 are arranged along a grid-like diagonal direction and along the row direction of the grid (e.g., ...). Figure 18 (as shown in the X direction) and column direction (as shown in the X direction) Figure 18 As shown in the Y direction, the first light trapping slots 130 are arranged at intervals, and adjacent first light trapping slots 130 along the row direction and adjacent first light trapping slots 130 along the column direction form a preset area D.

[0080] The first light trapping groove 130 is beneficial to improving the optical transmittance of the pixel area P, increasing the photoelectric conversion efficiency, and thus improving the optical sensitivity performance of the photoelectric sensor.

[0081] Specifically, the first light trapping groove 130 is disposed above the photoelectric element, which can slow down the change in refractive index between the air and the first surface 101, reduce the high reflectivity caused by the sudden change in refractive index at the interface, so that more light can enter the photoelectric element and improve the transmittance of incident light. Furthermore, by disposing the first light trapping groove 130 in the sub-pixel area 100a of the first surface 101, it is also beneficial to disperse the incident light to multiple angles, increase the effective optical path of the light, and thus play a role in trapping light.

[0082] In this embodiment, the first light trapping groove 130 is also used to provide a spatial location for the subsequent formation of a filling layer, so that the filling layer can serve as a mask for the subsequent formation of a second light trapping groove.

[0083] A preset region D is formed between adjacent first light trapping slots 130 along the row direction and adjacent first light trapping slots 130 along the column direction. The preset region D is used to form a second light trapping slot in the future.

[0084] Reference Figure 18 and Figure 19 , Figure 18 This is a top view. Figure 19 for Figure 18 A cross-sectional view along the 1-1' direction, as an example, shows that the first light trap 130 is an inverted pyramid structure.

[0085] By framing the first light-trapping groove 130 as an inverted pyramid structure, a gradual change in refractive index is created between the air and the first surface 101. This increases the number of reflections of light within the inverted pyramid structure, effectively reducing light reflectivity and allowing more light to enter the optoelectronic element, thus improving optical transmittance. Simultaneously, as incident light passes through the inverted pyramid structure of the first surface 101, it is dispersed at various angles through reflection, scattering, and refraction, increasing the effective optical path and thus trapping light, thereby improving the absorption efficiency of light in the optoelectronic element.

[0086] The steps for forming the first light trapping groove 130 in this embodiment will be described in detail below with reference to the accompanying drawings.

[0087] like Figures 10 to 15 As shown, a hard mask layer 120 is formed on the substrate 100, and a plurality of mask openings 125 are formed in the hard mask layer 120. The plurality of mask openings 125 are arranged along the diagonal of the grid in the sub-pixel area 100a, and along the row and column directions of the grid, the mask openings 125 are spaced apart.

[0088] The hard mask layer 120 is used as an etching mask for forming the first light trap.

[0089] The mask opening 125 is used to define the number and formation position of the first light trapping groove.

[0090] In this embodiment, the material of the hard mask layer 120 is silicon oxide.

[0091] Specifically, such as Figure 10 and Figure 11 As shown, Figure 10 This is a top view. Figure 11 for Figure 10 A cross-sectional view along secant line 1-1' shows a hard mask material layer 110 formed on the substrate 100; as shown... Figures 12 to 13 As shown, Figure 12 This is a top view. Figure 13 for Figure 12 A cross-sectional view along secant line 1-1' shows a patterned layer 111 formed on the hard mask material layer 110, with patterned openings 112 formed in the patterned layer 111; as shown... Figures 14 to 15 As shown, Figure 14 This is a top view. Figure 15 The image is a cross-sectional view along the 1-1' secant line. Using the pattern layer 111 as a mask, the hard mask material layer 110 exposed by the pattern opening 112 is etched, and the remaining hard mask material layer 110 is used as the hard mask layer 120.

[0092] The hard mask material layer 110 is used to form a hard mask layer.

[0093] As an example, the hard mask material layer 110 is formed using a deposition process (e.g., chemical vapor deposition).

[0094] The pattern layer 111 serves as a mask for patterning the hard mask material layer 110. The pattern openings 112 define the location and number of mask openings.

[0095] In this embodiment, the material of the pattern layer 111 is photoresist.

[0096] In this embodiment, using the pattern layer 111 as a mask, a dry etching process is employed to etch the hard mask material layer 110 exposed by the pattern opening 112. The dry etching process offers excellent profile control and also helps improve the accuracy of pattern transfer.

[0097] like Figures 16 to 17 As shown, the hard mask layer 120 is used as a mask, and the substrate 100 exposed by the mask opening 125 is etched to form the first light trapping groove 130.

[0098] In this embodiment, the substrate 100 is made of silicon and has multiple crystal planes. During the etching process to form the first light trapping groove 130, the etching rate varies for different crystal planes. <111> The etching rate of a crystal plane is lower than that of other crystal planes (e.g.: <100> The etching rate of the crystal plane, so that after etching the substrate 100 using the etching process, the sidewall of the first light trap 130 is <111> The crystal facets form the first light trap 130, which is a corresponding inverted pyramid structure.

[0099] In this embodiment, the process for forming the first light trap 130 includes a wet etching process. The etching solution in the wet etching process includes a TMAH (tetramethylammonium hydroxide) solution. The wet etching process utilizes the anisotropic etching rate of the TMAH solution on different crystal planes, more specifically... <111> The etching rate of a crystal plane is lower than that of other crystal planes (e.g.: <100> Crystal facets <110> The etching rate of the crystal plane enables the fabrication of the first light trap 130 with an inverted pyramid structure on the surface of the substrate 100.

[0100] Subsequent steps also include: forming a fill layer within the first light trapping groove 130. (See reference...) Figure 18 and Figure 19 In this embodiment, the method for forming the photoelectric sensor further includes: removing the hard mask layer 120 after forming the first light trapping groove 130 and before forming the filling layer.

[0101] Remove the hard mask layer 120 to free up the space above the first light trap 130, so that the subsequent filling layer can fill the first light trap 130.

[0102] In this embodiment, a wet etching process is used to remove the hard mask layer 120. Specifically, the material of the hard mask layer 120 is silicon oxide, and the etching solution of the wet etching process is a diluted hydrofluoric acid (DHF) solution.

[0103] It should be noted that in this embodiment, the removal of the hard mask layer 120 before forming the fill layer is used as an example. In other embodiments, the hard mask layer can also be removed during the step of forming the fill layer. Specifically, when the size of the mask opening in the hard mask layer after forming the first light trapping groove is such that it facilitates the subsequent filling of the fill layer within the first light trapping groove, the hard mask layer can be removed during the step of forming the fill layer. Accordingly, the step of forming the fill layer and the step of removing the hard mask layer can be integrated, which helps to simplify the process flow.

[0104] refer to Figure 20 This forms a filling layer 160 that fills the first light trap 130.

[0105] The filling layer 160 serves as a mask for subsequent etching of the preset region D, to form the second light trap.

[0106] Moreover, the filling layer 160 fills the first light trapping groove 130. Compared with the scheme of forming a grid-like arrangement of light trapping grooves in the sub-pixel area using a hard mask layer located on the substrate as a mask in the same step, the subsequent step of forming the second light trapping groove is beneficial to avoid the problem of falling and collapsing due to the small platform area between adjacent first and second light trapping grooves, which is conducive to reducing process risks.

[0107] The filler layer 160 is selected from a material that has etching selectivity with the material of the substrate 100, so as to ensure that the filler layer 160 is effective as an etching mask for etching the substrate 100 to form the second light trap.

[0108] As an example, the material of the filling layer 160 includes silicon oxide, silicon nitride, silicon oxynitride, or silicon carbide. Specifically, in this embodiment, the material of the filling layer 160 is silicon oxide. Silicon oxide has high compatibility with semiconductor process technology and low process cost.

[0109] The steps for forming the filling layer 160 in this embodiment will be described in detail below with reference to the accompanying drawings.

[0110] like Figures 20 to 21 As shown, Figure 20 This is a top view. Figure 21 for Figure 20 A cross-sectional view along line 1-1' shows a filling material layer 150 formed within the first light trapping groove 130, the filling material layer 150 also being formed on the substrate 100 on the side of the first light trapping groove 130.

[0111] In this embodiment, the process for forming the filling material layer 150 includes one or both of chemical vapor deposition (CVD) and atomic layer deposition (ALD). The process for forming the filling material layer 150 has good gap filling capability, which is beneficial to improving the filling quality of the filling material layer 150 in the first light trapping groove 130.

[0112] As an example, the filler material layer 150 is formed using a chemical vapor deposition (CVD) process. CVD is a low-cost and highly compatible process.

[0113] like Figures 22 to 25 As shown, the filling material layer 150 on the substrate 100 located on the side of the first light trap 130 is removed, and the remaining filling material layer 150 located in the first light trap 130 is used as the filling layer 160.

[0114] Remove the filling material layer 150 on the substrate 100 located on the side of the first light trapping groove 130 to expose the substrate 100 of the preset region D, so that a second light trapping groove can be formed in the substrate 100 of the preset region D.

[0115] Specifically, in this embodiment, as Figures 22 to 23 As shown, Figure 22 This is a top view. Figure 23 for Figure 22 A cross-sectional view along secant line 1-1' shows a planarization process used to remove a portion of the thickness of the filler material layer 150; as shown. Figures 24 to 25 As shown, Figure 24 This is a top view. Figure 25 for Figure 24 A cross-sectional view along line 1-1' shows the removal of the remaining filler material layer 150 on the substrate 100 located on the side of the first light trap 130 using an etching process.

[0116] In this embodiment, a planarization process is used to remove a portion of the thickness of the filler material layer 150, which helps to improve the flatness of the top surface of the remaining filler material layer 150, and correspondingly helps to improve the flatness of the top surface of the filler layer. Moreover, by using a planarization process to remove only a portion of the thickness of the filler material layer 150, a portion of the thickness of the filler material layer 150 is still retained on the substrate 100 on the side of the first light trapping groove 130, which helps to prevent the planarization process from damaging the substrate 100.

[0117] Specifically, in this embodiment, the planarization process can be a chemical mechanical planarization process.

[0118] In this embodiment, an etching process is used to remove the remaining filling material layer 150 on the substrate 100 located on the side of the first light trap 130. The etching process can easily achieve a large etching selectivity ratio between the filling material layer 150 and the substrate 100, which helps to reduce the probability of etching damage to the substrate 100.

[0119] Specifically, in this embodiment, a maskless dry etching process is used to etch the remaining filler material layer 150 to remove the remaining filler material layer 150 located on the substrate 100 on the side of the first light trap 130. Using a maskless etching process to etch the remaining filler material layer 150 to form the filler layer 160 also helps to eliminate the need for a photomask, thus saving costs.

[0120] It should be noted that in other embodiments, a planarization process may be used to remove the remaining filler material layer on the substrate located on the side of the first light trap.

[0121] It should also be noted that the foregoing steps are illustrated by example of removing the hard mask layer before forming the filler layer. In other embodiments, the hard mask layer can be removed during the step of forming the filler layer. Specifically, the hard mask layer is removed during the step of removing the remaining filler material layer on the substrate located on the side of the first light trap. Accordingly, the step of forming the filler layer and the step of removing the hard mask layer can be integrated, which helps to simplify the process flow.

[0122] refer to Figures 26 to 29 A second light trapping groove 140 is formed in the preset area D exposed by the filling layer 160, and the second light trapping groove 140 and the first light trapping groove 130 constitute a grid-like arrangement of light trapping grooves 200.

[0123] In this embodiment, adjacent first light trapping slots 130 along the row direction and adjacent first light trapping slots 130 along the column direction form a preset region D, and a filling layer 160 is formed within the first light trapping slots 130. Correspondingly, in the step of forming the second light trapping slot 140, the filling layer 160 within the first light trapping slot 130 can be used as a mask to form the second light trapping slot 140 within the preset region D exposed by the filling layer 160. The first light trapping slots 130 and the second light trapping slots 140 constitute a grid-like arrangement of light trapping slots 200. Compared with the scheme of forming a grid-like arrangement of light trapping slots in the sub-pixel area using a hard mask layer located on the first surface as a mask in the same step, this embodiment... In the process of forming the second light trap 140, since the filling layer 160 is filled in the first light trap 130, it is beneficial to avoid the problem that the hard mask layer (or filling layer) will lose support and fall down due to the small platform area between the adjacent first light trap and the second light trap. This is beneficial to reduce process risks. Moreover, it is also beneficial to make the size of the platform area between the first light trap 130 and the second light trap 140 smaller, or to make the adjacent first light trap 130 and the second light trap 140 seamlessly connected. This is beneficial to increase the density of the light trap 200, reduce the light reflectivity, and correspondingly improve the optical transmittance, thereby improving the performance of the photoelectric sensor.

[0124] The second light trap 140 helps to improve the optical transmittance of the pixel area P, increase the photoelectric conversion efficiency, and thus improve the optical sensitivity performance of the photoelectric sensor.

[0125] Specifically, as an example, the second light trap 140 is also an inverted pyramid structure.

[0126] By framing the first light-trapping groove 130 as an inverted pyramid structure, a gradual change in refractive index is created between the air and the first surface 101. This increases the number of reflections of light within the inverted pyramid structure, effectively reducing light reflectivity and allowing more light to enter the optoelectronic element, thus improving optical transmittance. Simultaneously, as incident light passes through the inverted pyramid structure of the first surface 101, it is dispersed at various angles through reflection, scattering, and refraction, increasing the effective optical path and thus trapping light, thereby improving the absorption efficiency of light in the optoelectronic element.

[0127] In this embodiment, during the formation of the second light trapping groove 140, the second light trapping groove 140 is seamlessly connected to the first light trapping groove 130.

[0128] In this embodiment, the seamless connection between the second light trapping groove 140 and the first light trapping groove 130 means that there is no platform area between the second light trapping groove 140 and the first light trapping groove 130. In other words, the size of the platform area between the second light trapping groove 140 and the first light trapping groove 130 is zero.

[0129] The seamless connection between the second light trapping groove 140 and the first light trapping groove 130 helps to further reduce the reflectivity of light in the pixel area, thereby improving the optical transmittance and thus enhancing the performance of the photoelectric sensor.

[0130] In this embodiment, the substrate 100 is made of silicon and has multiple crystal planes. During the etching process to form the second light trapping groove 140 by etching the exposed substrate 100 of the filling layer 160, the etching rate varies for different crystal planes. <111> The etching rate of a crystal plane is lower than that of other crystal planes (e.g.: <100> The etching rate of the crystal plane, so that after the substrate 100 exposed by the filling layer 160 is etched using an etching process, the sidewall of the second light trap 140 is <111> The crystal facets form a second light trap 140, which is a corresponding inverted pyramid structure.

[0131] In this embodiment, the process for forming the second light trapping groove 140 includes a wet etching process.

[0132] In this embodiment, the filling layer 160 used as an etching mask does not have the risk of collapsing. Accordingly, the filling layer 160 is not likely to fall into the etching solution of the wet etching process, which reduces the probability of contaminating the etching solution. As a result, after using the etching solution to etch subsequent products, the risk of particle defects in subsequent products can be reduced.

[0133] In this embodiment, the etching solution in the wet etching process includes a TMAH (tetramethylammonium hydroxide) solution. The wet etching process utilizes the anisotropic etching rate of the TMAH solution on different crystal planes, more specifically... <111> The etching rate of a crystal plane is lower than that of other crystal planes (e.g.: <100> Crystal facets <110> The etching rate of the crystal plane enables the fabrication of a second light trap 140 with an inverted pyramid structure on the surface of the substrate 100.

[0134] As one embodiment, the method for forming the photoelectric sensor further includes: referencing Figure 28 and Figure 29 , Figure 28 This is a top view. Figure 29 for Figure 28In the cross-sectional view along line 1-1', after the second light trapping groove 140 is formed, the filler layer 160 is removed. Removing the filler layer 160 exposes the first light trapping groove 130, facilitating subsequent deposition of a film layer within the first light trapping groove 130.

[0135] In this embodiment, the process for removing the filler layer 160 includes a wet etching process. Specifically, the material of the filler layer 160 is silicon oxide, and the etching solution for the wet etching process is a hydrofluoric acid solution.

[0136] It should be noted that in this embodiment, the example is taken as removing the filling layer 160 after the second light trapping groove 140 is formed.

[0137] In other embodiments, based on actual process requirements, after forming the second light-trapping groove, the filling layer located within the first light-trapping groove can be retained. This filling layer can serve as a light-transmitting layer, thereby integrating with the process of forming the light-transmitting layer and eliminating the need for removing the filling layer, which improves process integration. Accordingly, the filling layer is made of an insulating dielectric material to avoid affecting the electrical performance of the photoelectric sensor. Furthermore, the filling layer is also made of a light-transmitting material to ensure normal light transmission in the pixel area.

[0138] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for forming a photoelectric sensor, characterized in that, include: A substrate is provided, the substrate including a pixel region, the pixel region including a plurality of sub-pixel regions arranged in an array; a plurality of photosensitive units are formed in the substrate, the area where the photosensitive units are located is a sub-pixel region; Multiple first light trapping grooves are formed in the substrate surface of the sub-pixel area. In the sub-pixel area, the multiple first light trapping grooves are arranged along the diagonal direction of the grid, and along the row and column directions of the grid, the first light trapping grooves are spaced apart, and adjacent first light trapping grooves along the row direction and adjacent first light trapping grooves along the column direction form a preset area. A filling layer is formed within the first light trapping groove; Using the filling layer as a mask, a second light trapping groove is formed in the preset area exposed by the filling layer. The second light trapping groove and the first light trapping groove constitute a grid-like arrangement of light trapping grooves.

2. The method for forming a photoelectric sensor as described in claim 1, characterized in that, During the formation of the second light trapping groove, the second light trapping groove is seamlessly connected to the first light trapping groove.

3. The method for forming a photoelectric sensor as described in claim 1, characterized in that, The step of forming the first light trapping groove includes: forming a hard mask layer on the substrate, wherein a plurality of mask openings are formed in the hard mask layer, the plurality of mask openings are arranged along the diagonal of the grid in the sub-pixel area, and along the row and column directions of the grid, and the mask openings are spaced apart from each other. Using the hard mask layer as a mask, the substrate exposed by the mask opening is etched to form the first light trapping groove.

4. The method for forming a photoelectric sensor as described in claim 3, characterized in that, The method for forming the photoelectric sensor further includes: removing the hard mask layer after forming the first light-trapping groove and before forming the filling layer; or, In the step of forming the filler layer, the hard mask layer is removed.

5. The method for forming a photoelectric sensor as described in claim 1, characterized in that, The step of forming the filling layer includes: forming a filling material layer in the first light trapping groove, the filling material layer also being formed on the substrate on the side of the first light trapping groove; removing the filling material layer on the substrate on the side of the first light trapping groove, and using the remaining filling material layer in the first light trapping groove as the filling layer.

6. The method for forming a photoelectric sensor as described in claim 5, characterized in that, The process for forming the filling material layer includes one or both of chemical vapor deposition and atomic layer deposition.

7. The method for forming a photoelectric sensor as described in claim 1, characterized in that, The process for forming the first light trapping groove includes a wet etching process.

8. The method for forming a photoelectric sensor as described in claim 1, characterized in that, The process for forming the second light trapping groove includes a wet etching process.

9. The method for forming a photoelectric sensor as described in claim 7 or 8, characterized in that, The etching solution used in the wet etching process includes a TMAH solution.

10. The method for forming a photoelectric sensor as described in claim 1, characterized in that, The method for forming the photoelectric sensor further includes removing the filling layer after forming the second light trapping groove.

11. The method for forming a photoelectric sensor as described in claim 10, characterized in that, The process for removing the filler layer includes a wet etching process.

12. A photoelectric sensor, characterized in that, include: A substrate, the substrate including a pixel region, the pixel region including a plurality of sub-pixel regions arranged in an array; Multiple first light traps are located on the substrate surface of the sub-pixel region. In the sub-pixel region, the multiple first light traps are arranged along the diagonal direction of the grid, and along the row and column directions of the grid, the first light traps are spaced apart, and adjacent first light traps along the row direction and adjacent first light traps along the column direction form a preset area. Multiple second light traps are located within the substrate of the preset area, and the second light traps and the first light traps form a grid-like arrangement of light traps. A filling layer is placed inside the first light trapping groove.

13. The photoelectric sensor as described in claim 12, characterized in that, The first light trapping groove and the second light trapping groove are seamlessly connected.

14. The photoelectric sensor as described in claim 12, characterized in that, The filling layer is made of silicon oxide, silicon nitride, silicon oxynitride, or silicon carbide.

15. The photoelectric sensor as described in claim 12, characterized in that, The light trapping groove has an inverted pyramid structure.

16. An electronic device, characterized in that, include: The photoelectric sensor as described in any one of claims 12 to 15.

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