CN113345925B - Pixel unit, image sensor and spectrometer - Google Patents

Abstract

The invention provides a pixel unit, an image sensor and a spectrometer, wherein the pixel unit comprises a photoelectric conversion structure and a superlens structure, and the photoelectric conversion structure can generate current under illumination; the super lens structure is arranged on the photoelectric conversion structure, and can screen light with preset wavelength from the light image and focus the light with preset wavelength on the photoelectric conversion structure. The pixel unit, the image sensor and the spectrometer provided by the invention can improve the integration level of the pixel unit and improve the color cast and the color difference, so that the volumes of the image sensor and the spectrometer can be reduced and the imaging effect can be improved.

Description

Pixel unit, image sensor and spectrometer

Technical Field

The present invention relates to the field of display technology, and in particular to a pixel unit, an image sensor and a spectrometer.

Background technique

Image sensor, also known as photosensitive element, is a functional device that uses the photoelectric conversion function of photoelectric devices to convert the light image on the photosensitive surface into an electrical signal that is proportional to the light image. It is mainly used in electronic optical imaging equipment such as spectrometers, hyperspectral imagers, and digital cameras.

There are mainly two types of image sensors, namely CCD (Charge-coupled Device) image sensors and CMOS (Complementary Metal Oxide Semiconductor) image sensors. Both of these image sensors include multiple pixel units, so that the light image on its photosensitive surface can be divided into multiple small units, and the multiple small unit light images are converted into usable electrical signals corresponding to each small unit light image with the help of multiple pixel units, thereby obtaining electrical signals with a corresponding proportional relationship with the light image.

However, the existing pixel units have a low degree of integration and are prone to chromatic aberration and color deviation, which results in larger size of image sensors and electronic optical imaging devices such as spectrometers, hyperspectral imagers, digital cameras, etc. that use pixel units, and poor imaging effects such as low imaging light intensity and low imaging resolution.

Summary of the invention

The present invention aims to solve at least one of the technical problems existing in the prior art, and proposes a pixel unit, an image sensor and a spectrometer, which can improve the integration of the pixel unit and improve color deviation and chromatic aberration, thereby reducing the volume of the image sensor and the spectrometer and improving the imaging effect.

To achieve the above-mentioned purpose, the present invention provides a pixel unit, including a photoelectric conversion structure and a super lens structure, wherein the photoelectric conversion structure can generate current under light; the super lens structure is arranged on the photoelectric conversion structure, and the super lens structure can filter out light of a preset wavelength from the light image and focus the light of the preset wavelength on the photoelectric conversion structure.

Optionally, the superlens structure includes a light-transmitting substrate and a plurality of supersurface structure units, wherein the substrate is arranged on the photoelectric conversion structure, the plurality of supersurface structure units are arranged on a side surface of the substrate away from the photoelectric conversion structure, and are distributed in an array, and the length of each of the supersurface structure units in the vertical direction is less than the preset wavelength, and the plurality of supersurface structure units can cooperate to filter out light of a preset wavelength from the light image and focus the light of the preset wavelength on the photoelectric conversion structure.

Optionally, the shape of each of the supersurface structural units includes any one of a prism, a cylinder, a sphere and an ellipsoid.

Optionally, each of the super-surface structure units is in the shape of a rectangular cylinder, the long axis of each of the super-surface structure units is parallel to a side of the substrate away from the photoelectric conversion structure, and the long axis of each of the super-surface structure units has an angle of preset degrees with a first preset direction, and the first preset direction is parallel to a side of the substrate away from the photoelectric conversion structure, so that the multiple super-surface structure units cooperate to focus the light of the preset wavelength on the photoelectric conversion structure.

Optionally, the side surface of the substrate away from the photoelectric conversion structure is in a square shape, and the side surface of the substrate away from the photoelectric conversion structure is divided into a plurality of square sub-surfaces, the number of the sub-surfaces is the same as the number of the super-surface structure units, and the plurality of super-surface structure units are arranged on the plurality of sub-surfaces in a one-to-one correspondence, and the preset degree of the angle between the long axis of each of the super-surface structure units and the first preset direction is obtained by the following formula:

Among them, θ is the angle of the preset degree between the long axis of the supersurface structure unit and the first preset direction, π is the pi, λ is the preset wavelength, f is the focal length, x is the position coordinate of the side of the substrate away from the photoelectric conversion structure in the first preset direction, y is the position coordinate of the side of the substrate away from the photoelectric conversion structure in the second preset direction perpendicular to the first preset direction, and s is the side length of the side of the substrate away from the photoelectric conversion structure.

Optionally, the manufacturing material of each of the super surface structure units includes any one of a-Si, p-Si, Si3N4 and TiO2.

Optionally, the photoelectric conversion structure includes a photoelectric conversion metal part, a substrate and a light-transmitting insulating layer, wherein the insulating layer is arranged on the substrate, the photoelectric conversion metal part is arranged in the insulating layer, the photoelectric conversion metal part can generate current under light, and the super lens structure is arranged on a side surface of the insulating layer away from the substrate.

Optionally, there are multiple photoelectric conversion metal parts, and the multiple photoelectric conversion metal parts are arranged in the insulating layer at intervals.

Optionally, the pixel unit further includes a light-transmitting protective layer, which covers a side surface of the superlens structure away from the photoelectric conversion structure, and is used to protect the superlens structure.

Optionally, the protective layer is made of a material including polymethyl methacrylate or polydimethylsiloxane.

The present invention also provides an image sensor, comprising at least three pixel units as provided by the present invention, wherein the at least three pixel units are distributed in an array, and the at least three pixel units are capable of at least respectively screening out red light, green light and blue light from a light image, and respectively focusing the red light, green light and blue light, and respectively generating currents corresponding to the red light, green light and blue light.

The present invention also provides a spectrometer, comprising a plurality of pixel units as provided by the present invention, wherein the plurality of pixel units are distributed in an array, and the plurality of pixel units are at least capable of respectively screening out visible light of different wavelengths from a light image, and respectively focusing the visible light of different wavelengths, and generating currents corresponding to the visible light of different wavelengths.

The present invention has the following beneficial effects:

The pixel unit provided by the present invention is provided with a super lens structure on a photoelectric conversion structure, so that the super lens structure can filter out light of a preset wavelength from a light image, and focus the light of the preset wavelength on the photoelectric conversion structure, so that the photoelectric conversion structure can generate current under light. Since the super lens structure can filter out light of a preset wavelength from a light image, and focus the light of the preset wavelength on the photoelectric conversion structure, that is, the super lens structure has a color filter (Color filter) in an existing pixel unit. The metalens structure has a function of filtering out light of a preset wavelength from a light image, and has a function of focusing light of a preset wavelength by a curved lens in an existing pixel unit. Therefore, the metalens structure can replace the color filter and the curved lens in the existing pixel unit to avoid the chromatic aberration and color deviation caused by the uneven bonding of the color filter and the curved lens in the existing pixel unit, thereby improving the color deviation and chromatic aberration of the pixel unit, and then improving the imaging effects of the image sensor and the spectrometer, such as imaging light intensity and imaging resolution. Moreover, since the metalens structure can be directly prepared and integrated on the photoelectric conversion structure through a semiconductor process, the problem of low integration of the existing pixel unit due to the need to bond the curved lens to the photoelectric conversion structure can be avoided, and there is no need to bond the color filter and the curved lens, thereby improving the integration of the pixel unit, and improving the color deviation and chromatic aberration, thereby reducing the volume of the image sensor and the spectrometer, and improving the imaging effects of the image sensor and the spectrometer, such as imaging light intensity and imaging resolution.

The image sensor provided by the present invention uses at least three pixel units provided by the present invention to respectively filter out red light, green light and blue light from a light image, and respectively focus the red light, green light and blue light, and respectively generate currents corresponding to the red light, green light and blue light, thereby reducing the volume of the image sensor and the spectrometer and improving the imaging effect.

The spectrometer provided by the present invention uses a plurality of pixel units provided by the present invention to screen out visible light of different wavelengths from a light image, respectively focus the visible light of different wavelengths, and generate currents corresponding to the visible light of different wavelengths, thereby reducing the volume of the spectrometer and improving the imaging effect.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic structural diagram of a pixel unit of an existing plasma filter;

FIG2 is a schematic diagram of the structure of a pixel unit provided by an embodiment of the present invention;

FIG3 is a schematic structural diagram of a substrate of a pixel unit and a plurality of super-surface structure units provided in an embodiment of the present invention;

FIG4 is a schematic diagram of a pixel unit focusing light according to an embodiment of the present invention;

FIG5 is a schematic diagram of light focused on a surface by a pixel unit according to an embodiment of the present invention;

FIG6 is a schematic diagram of light focused by a pixel unit on another surface provided by an embodiment of the present invention;

FIG7 is a schematic diagram of a high-level metasurface structure unit of a pixel unit provided by an embodiment of the present invention;

FIG8 is a schematic diagram of the length and width of a super-surface structure unit of a pixel unit provided by an embodiment of the present invention;

FIG9 is a schematic diagram of the angle of a super-surface structure unit of a pixel unit provided by an embodiment of the present invention;

FIG10 is a schematic structural diagram of a pixel unit provided by an embodiment of the present invention at a step in a manufacturing process;

FIG11 is a schematic structural diagram of a pixel unit provided by an embodiment of the present invention at another step in the preparation process;

FIG12 is a schematic structural diagram of a pixel unit provided by an embodiment of the present invention at another step in the preparation process;

FIG13 is a schematic structural diagram of a pixel unit provided by an embodiment of the present invention at another step in the preparation process;

FIG14 is a schematic structural diagram of a pixel unit provided by an embodiment of the present invention at another step in the preparation process;

FIG15 is a schematic structural diagram of a pixel unit provided by an embodiment of the present invention at another step in the preparation process;

FIG16 is a schematic structural diagram of a pixel unit provided by an embodiment of the present invention at another step in the preparation process;

FIG17 is a schematic diagram of the structure of a spectrometer provided in an embodiment of the present invention;

FIG18 is a schematic diagram of the three-dimensional structure of a spectrometer provided in an embodiment of the present invention;

Description of reference numerals:

1-pixel unit; 11-photoelectric conversion structure; 111-substrate; 112-photoelectric conversion metal piece; 113-light-transmitting insulating layer; 12-super lens structure; 121-base; 122-super surface structure unit; 13-protective layer; 2-spectrometer; 31-plasma filter; 32-curved lens; 33-photoelectric conversion structure; 41-photoresist.

Detailed ways

In order to enable those skilled in the art to better understand the technical solution of the present invention, the pixel unit, image sensor and spectrometer provided by the present invention are described in detail below with reference to the accompanying drawings.

In order to enable those skilled in the art to better understand the technical solution of the present invention, two existing pixel units are first introduced. The first existing pixel unit includes an organic dye filter, a curved lens and a photoelectric conversion structure, wherein the curved lens is bonded to the photoelectric conversion structure, the organic dye filter is bonded to the curved lens and is located on the side of the curved lens away from the photoelectric conversion structure, the light image is incident from one side of the organic dye filter, the organic dye filter screens out light of a preset wavelength from the light image, and the light of the preset wavelength is incident on the curved lens through the organic dye filter, the curved lens focuses the light of the preset wavelength on the photoelectric conversion structure, and the photoelectric conversion structure generates a current corresponding to the light of the preset wavelength under the irradiation of the light of the preset wavelength.

However, since organic dyes cannot withstand high temperatures or prolonged ultraviolet radiation, the working stability of pixel units using organic dye filters is poor. Moreover, since the absorption coefficient of organic dyes is low, the thickness of organic dye filters is usually thicker and cannot be designed as a film layer with a thickness of several hundred nanometers. Furthermore, since the organic dye filter and the curved lens, as well as the curved lens and the photoelectric conversion structure, need to be bonded together to be integrated, that is, the organic dye filter cannot be directly prepared and integrated on the curved lens, and the curved lens cannot be directly prepared and integrated on the photoelectric conversion structure. Therefore, the integration degree of the pixel unit is low. Moreover, the degree of alignment between the organic dye filter and the photoelectric conversion structure will affect the current generated by the photoelectric conversion structure, which requires the bonding of the organic dye filter and the curved lens, as well as the bonding of the curved lens and the photoelectric conversion structure to be aligned. If the bonding of the organic dye filter and the curved lens, or the bonding of the curved lens and the photoelectric conversion structure are not aligned, color deviation and chromatic aberration will occur, resulting in poor imaging effects of the image sensor and the spectrometer, such as low imaging light intensity and low imaging resolution.

As shown in FIG1 , the second existing pixel unit includes a plasma filter 31, a curved lens 32 and a photoelectric conversion structure 33, wherein the curved lens 32 is bonded to the photoelectric conversion structure 33, and the plasma filter 31 is bonded to the curved lens 32 and is located on the side of the curved lens 32 away from the photoelectric conversion structure 33. The plasma filter 31 refers to a filter having a plasma air hole array structure based on a metal (e.g., aluminum) film, which utilizes the interference effect of adjacent plasma air holes on light so as to filter out light of a preset wavelength from a light image. The light image is incident from one side of the plasma filter 31, and the light of the preset wavelength is incident on the curved lens 32 through the plasma filter 31. The curved lens 32 focuses the light of the preset wavelength on the photoelectric conversion structure 11, and the photoelectric conversion structure generates a current corresponding to the light of the preset wavelength under the irradiation of the light of the preset wavelength.

However, since the plasma filter 31 and the curved lens 32, as well as the curved lens 32 and the photoelectric conversion structure 33, need to be bonded together to be integrated, that is, the plasma filter 31 cannot be directly prepared and integrated on the curved lens 32, and the curved lens 32 cannot be directly prepared and integrated on the photoelectric conversion structure 33, the integration degree of the pixel unit is low, and the alignment degree of the plasma filter 31 and the photoelectric conversion structure 33 will affect the current generated by the photoelectric conversion structure 33, which requires the bonding of the plasma filter 31 and the curved lens 32, as well as the bonding of the curved lens 32 and the photoelectric conversion structure 33 to be aligned. If the bonding of the plasma filter 31 and the curved lens 32, or the bonding of the curved lens 32 and the photoelectric conversion structure 33 are not aligned, color deviation and chromatic aberration will occur, resulting in poor imaging effects of the image sensor and the spectrometer, such as low imaging light intensity and low imaging resolution. In addition, since the metal (such as aluminum) thin film substrate of the plasma filter 31 will generate ohmic loss, the service life of the pixel unit will also be reduced.

As shown in Figure 2, an embodiment of the present invention provides a pixel unit 1, including a photoelectric conversion structure 11 and a super lens structure 12, wherein the photoelectric conversion structure 11 can generate current under light; the super lens structure 12 is arranged on the photoelectric conversion structure 11, and the super lens structure 12 can filter out light of a preset wavelength from the light image and focus the light of the preset wavelength on the photoelectric conversion structure 11.

The pixel unit 1 provided by the embodiment of the present invention sets a super lens structure 12 on the photoelectric conversion structure 11, so as to screen out light of a preset wavelength from the light image with the help of the super lens structure 12, and focus the light of the preset wavelength on the photoelectric conversion structure 11, so that the photoelectric conversion structure 11 can generate current under light. Since the super lens structure 12 can screen out light of a preset wavelength from the light image, and focus the light of the preset wavelength on the photoelectric conversion structure 11, that is, the super lens structure 12 has the function of the color filter in the existing pixel unit 1 to screen out light of a preset wavelength from the light image, and has the function of the curved lens in the existing pixel unit 1 to focus light of a preset wavelength. Therefore, the super lens structure 12 can replace the color filter and the curved lens in the existing pixel unit 1, so as to avoid the existing pixel unit The chromatic aberration and color deviation caused by the uneven bonding of the color filter and the curved lens occur, so that the color deviation and color deviation of the pixel unit 1 can be improved, and then the imaging effects of the image sensor and the spectrometer 2, such as imaging light intensity and imaging resolution, can be improved. Moreover, since the super lens structure 12 can be directly prepared and integrated on the photoelectric conversion structure 11 through a semiconductor process, the problem of low integration of the existing pixel unit 1 caused by the need to bond the curved lens to the photoelectric conversion structure 11 can be avoided, and there is no need to bond the color filter and the curved lens, so that the integration of the pixel unit 1 can be improved, and the color deviation and color deviation can be improved, and then the volume of the image sensor and the spectrometer 2 can be reduced, and the imaging effects of the image sensor and the spectrometer 2, such as imaging light intensity and imaging resolution, can be improved.

Optionally, the preset wavelengths for different super-lens structures 12 may be different. For example, the preset wavelength of one super-lens structure 12 among three different super-lens structures 12 may be 660 nm, that is, the super-lens structure 12 can filter out 660 nm light from the light image and focus the 660 nm light on the photoelectric conversion structure 11. The preset wavelength of another super-lens structure 12 among the three different super-lens structures 12 may be 532 nm, that is, the super-lens structure 12 can filter out 532 nm light from the light image and focus the 532 nm light on the photoelectric conversion structure 11. The preset wavelength of another super-lens structure 12 among the three different super-lens structures 12 may be 405 nm, that is, the super-lens structure 12 can filter out 405 nm light from the light image and focus the 405 nm light on the photoelectric conversion structure 11.

As shown in Figures 5 and 6, it is a schematic diagram of the super lens structure 12 focusing light, wherein x represents the horizontal coordinate in the Cartesian coordinate system established with the photoelectric conversion structure 11 facing the side of the substrate 121, y represents the vertical coordinate in the Cartesian coordinate system, and z represents the vertical coordinate in the Cartesian coordinate system. The units of x, y, and z are all microns, and the coordinate on the right side of the figure represents the energy of the light. As shown in Figures 5 and 6, the super lens structure 12 focuses the light on the center position of the side surface of the photoelectric conversion structure 11 facing the substrate 121 represented by xy, and focuses the light on one side of the side represented by yz. However, the position where the super lens structure 12 focuses the light on the side surface of the photoelectric conversion structure 11 facing the substrate 121 represented by xy, and the position where the light is focused on the side surface represented by yz are not limited to this, and can be adjusted as needed.

As shown in Figures 2 and 3, in one embodiment of the present invention, the superlens structure 12 may include a light-transmitting substrate 121 and a plurality of supersurface structure units 122, wherein the substrate 121 is arranged on the photoelectric conversion structure 11, and the plurality of supersurface structure units 122 are all arranged on a side surface of the substrate 121 away from the photoelectric conversion structure 11, and are distributed in an array, and the length of each supersurface structure unit 122 in the vertical direction is less than a preset wavelength, and the plurality of supersurface structure units 122 can cooperate to filter out light of a preset wavelength from the light image, and focus the light of the preset wavelength on the photoelectric conversion structure 11.

The length of the metasurface structure unit 122 in the vertical direction is less than the preset wavelength, that is, the thickness of the metasurface structure unit 122 on the substrate 121 is less than the preset wavelength. This metasurface structure unit 122 can be called a metasurface lens. Since the refractive index of a substance is related to the magnetic permeability and dielectric constant of the medium, when the magnetic permeability and dielectric constant of the medium are both greater than 0, the refractive index of the substance is greater than 0, and when the magnetic permeability and dielectric constant of the medium are both less than 0, the refractive index of the substance is less than 0. A substance that has both a negative dielectric constant and a negative magnetic permeability is called a metamaterial. This metamaterial has unusual optical properties relative to conventional substances. For example, a When a pen is inserted into the metamaterial liquid, the image of the pen seems to be outside the metamaterial liquid, and the matter leaving the metamaterial liquid will be blue-shifted (conventional matter is red-shifted). This metamaterial can be obtained by making the size of the metamaterial itself smaller than the wavelength of the electromagnetic wave. Therefore, by making the vertical length of the metasurface structure unit 122 smaller than the preset wavelength, the metasurface structure unit 122 can obtain this metamaterial effect, and by distributing multiple metasurface structure units 122 in an array, the preset wavelength can be screened out from the light image with the help of the refraction of the multiple metasurface structure units 122, and the light of the preset wavelength can be focused (as shown in Figure 4).

As shown in Figure 4, it should be noted that the light focused by multiple super-surface structure units 122 is not completely focused on one point when passing through the substrate 121. After passing through a certain thickness of the substrate 121 and irradiating the photoelectric conversion structure 11, it will be completely focused on a point on the photoelectric conversion structure 11.

Optionally, the material of each super surface structure unit 122 may include any one of a-Si, p-Si, silicon nitride (Si ₃ N ₄ ) and titanium dioxide (TiO ₂ ). That is, the material of each super surface structure unit 122 may be a-Si, or p-Si, or Si ₃ N ₄ , or TiO ₂ .

Optionally, the substrate 121 may be made of silicon dioxide (SiO ₂ ).

Optionally, the shape of each super surface structure unit 122 may include any one of a prism, a cylinder, a sphere, and an ellipsoid. That is, the shape of each super surface structure unit 122 may be a prism, a cylinder, a sphere, or an ellipsoid.

As shown in Figures 7 to 9, in one embodiment of the present invention, the shape of each supersurface structure unit 122 can be a rectangular cylinder, the long axis of each supersurface structure unit 122 is parallel to the side of the substrate 121 away from the photoelectric conversion structure 11, and the long axis of each supersurface structure unit 122 has an angle of preset degrees with the first preset direction, and the first preset direction is parallel to the side of the substrate 121 away from the photoelectric conversion structure 11, so that multiple supersurface structure units 122 cooperate to focus light of a preset wavelength on the photoelectric conversion structure 11.

As shown in Figures 7 to 9, the long side (as shown by side L in Figure 8) and the wide side (as shown by side W in Figure 8) of each super-surface structure unit 122 in the form of a rectangular column are parallel to the side of the substrate 121 away from the photoelectric conversion structure 11, and the high side (as shown by side h in Figure 7) of each super-surface structure unit 122 in the form of a rectangular column is perpendicular to the side of the substrate 121 away from the photoelectric conversion structure 11, and the long axis of each super-surface structure unit 122 in the form of a rectangular column has an angle of a preset degree with the first preset direction (as shown by angle θ in Figure 9), and the first preset direction can be any direction parallel to the side of the substrate 121 away from the photoelectric conversion structure 11. According to the principle of geometric phase, every time the angle between the long axis of the metasurface structure unit 122 and the first preset direction changes by a certain degree, the phase of the light will change by twice the preset degree after passing through the metasurface structure unit 122. Therefore, by adjusting the preset degree of the angle between the long axis of each metasurface structure unit 122 in the plurality of metasurface structure units 122 distributed in an array and the first preset direction, the light with a preset wavelength can be screened out from the light image with the help of the refraction coordination of the plurality of metasurface structure units 122, and the light with the preset wavelength can be focused on the photoelectric conversion structure 11.

Optionally, the preset degrees of the angles between the long axes of different metasurface structure units 122 and the first preset direction may be different.

However, the shape of each super-surface structure unit 122 and the manner in which multiple super-surface structure units 122 cooperate to focus light of a preset wavelength on the photoelectric conversion structure 11 are not limited thereto. For example, the shape of each super-surface structure unit 122 can be spherical. In this case, the radius of each super-surface structure unit 122 in the multiple super-surface structure units 122 distributed in an array can be adjusted so that the refraction coordination of the multiple super-surface structure units 122 can filter out the preset wavelength from the light image and focus the light of the preset wavelength.

In one embodiment of the present invention, the shape of the side of the substrate 121 away from the photoelectric conversion structure 11 can be square, and the side of the substrate 121 away from the photoelectric conversion structure 11 can be divided into a plurality of square sub-surfaces, the number of sub-surfaces is the same as the number of super-surface structure units 122, and the plurality of super-surface structure units 122 are arranged on the plurality of sub-surfaces in a one-to-one correspondence. The preset degree of the angle between the long axis of each super-surface structure unit 122 and the first preset direction can be obtained by the following formula:

Among them, θ is the preset angle between the long axis of the supersurface structure unit 122 and the first preset direction, π is the pi, λ is the preset wavelength, f is the focal length, x is the position coordinate of the side of the substrate 121 away from the photoelectric conversion structure 11 in the first preset direction, y is the position coordinate of the side of the substrate 121 away from the photoelectric conversion structure 11 in the second preset direction perpendicular to the first preset direction, and s is the side length of the side of the substrate 121 away from the photoelectric conversion structure 11.

As shown in Figures 7 to 9, it is a schematic diagram of a supersurface structure unit 122 on a square sub-surface, the height of the supersurface structure unit 122 is h, the length is L, and the width is W. The side length of the square sub-surface is a, and the square sub-surface with a side length of a is divided by a side of the square substrate 121 away from the photoelectric conversion structure 11. The side length of the side of the square substrate 121 away from the photoelectric conversion structure 11 is s, and a supersurface structure unit 122 is arranged on the square sub-surface with a side length of a. For example, a Cartesian coordinate system is established with a side of the square substrate 121 away from the photoelectric conversion structure 11, and the center of the side of the square substrate 121 away from the photoelectric conversion structure 11 is taken as the origin, then x can be the abscissa in the Cartesian coordinate system, and y can be the ordinate in the Cartesian coordinate system. It can be seen from the above formula that the preset degree of the angle between the long axis of each super-surface structure unit 122 and the first preset direction is related to the position of each super-surface structure unit 122 on the side of the substrate 121 away from the photoelectric conversion structure 11, the focal length, and the preset wavelength. Since multiple super-surface structure units 12 The wavelength of light to be screened out from the light image and the required focal length can be pre-designed. For example, the focal length can be pre-designed according to the position at which the light is focused on the photoelectric conversion structure 11 as required. Therefore, according to the position of each metasurface structure unit 122 on a side of the substrate 121 away from the photoelectric conversion structure 11, the preset degree of the angle between the long axis of each metasurface structure unit 122 and the first preset direction can be determined by the above formula, thereby adjusting the preset degree of the angle between the long axis of each metasurface structure unit 122 in the plurality of metasurface structure units 122 distributed in an array and the first preset direction.

For example, a super surface structure unit 122 has a width of 85nm, a length of 410nm, and a height of 600nm, and the side length of the square sub-surface where it is located is 430nm, then it can focus light with a wavelength of 660nm. For example, another super surface structure unit 122 has a width of 95nm, a length of 250nm, and a height of 600nm, and the side length of the square sub-surface where it is located is 325nm, then it can focus light with a wavelength of 532nm. For example, another super surface structure unit 122 has a width of 40nm, a length of 150nm, and a height of 600nm, and the side length of the square sub-surface where it is located is 200nm, then it can focus light with a wavelength of 405nm.

As shown in Figure 2, in one embodiment of the present invention, the photoelectric conversion structure 11 may include a photoelectric conversion metal part 112, a substrate 111 and a light-transmitting insulating layer 113, wherein the insulating layer is arranged on the substrate 111, the photoelectric conversion metal part 112 is arranged in the insulating layer, the photoelectric conversion metal part 112 can generate current under light, and the super lens structure 12 is arranged on the side surface of the insulating layer away from the substrate 111.

As shown, taking the example of a superlens structure 12 including a light-transmitting base 121 and a plurality of supersurface structure units 122, the base 121 is arranged on the side of the insulating layer away from the substrate 111, and the light focused by the plurality of supersurface structure units 122 will sequentially pass through the base 121 and the insulating layer to irradiate the photoelectric conversion metal part 112, so that the photoelectric conversion metal part 112 generates current.

Optionally, the material of the photoelectric conversion metal member 112 may include copper.

Optionally, the material of the substrate 111 may include silicon (Si).

Optionally, the material of the insulating layer may include silicon nitride (Si ₃ N ₄ ).

As shown in FIG2 , in one embodiment of the present invention, there may be multiple photoelectric conversion metal parts 112, and multiple photoelectric conversion metal parts 112 are arranged at intervals in the insulating layer. The photoelectric conversion effect can be improved by using multiple photoelectric conversion metal parts 112, and by arranging multiple photoelectric conversion metal parts 112 at intervals in the insulating layer, the multiple photoelectric conversion metal parts 112 can be insulated by the insulating layer to avoid short circuits between the multiple photoelectric conversion metal parts 112.

As shown in FIG. 2 , in one embodiment of the present invention, the pixel unit 1 may further include a light-transmitting protective layer 13 , which covers a side surface of the super lens structure 12 away from the photoelectric conversion structure 11 , and is used to protect the super lens structure 12 .

Optionally, the material of the protective layer 13 may include polymethylmethacrylate (PMMA for short) or polydimethylsiloxane (PDMS for short).

As shown in Figures 10 to 16, the preparation process of the pixel unit 1 provided in an embodiment of the present invention is introduced by taking the example that the super lens structure 12 includes a light-transmitting substrate 121 and multiple super surface structure units 122, the photoelectric conversion structure 11 includes a photoelectric conversion metal part 112, a substrate 111 and a light-transmitting insulating layer 113, and the pixel unit 1 also includes a light-transmitting protective layer 13. As shown in FIG10 , first, a photoelectric conversion structure 11 including a plurality of photoelectric conversion metal parts 112, a substrate 111 and a light-transmitting insulating layer 113 can be manufactured, wherein the insulating layer is prepared on the substrate 111, and the plurality of photoelectric conversion metal parts 112 are prepared in the insulating layer at intervals. Subsequently, as shown in FIG11 , a substrate 121 can be deposited on a side of the insulating layer away from the substrate 111 by a plasma enhanced chemical vapor deposition (PECVD) process. Subsequently, as shown in FIG12 , a photoresist can be prepared on a side of the substrate 121 away from the insulating layer by a spin coating exposure developer process to form a pattern adapted to the pattern of the plurality of metasurface structure units 122. Subsequently, as shown in FIG13 , a material (e.g., TiO ₂ ) of the metasurface structure unit 122 can be deposited on the photoresist and in the pattern formed by the photoresist by an atomic layer deposition (ALD) process. Subsequently, as shown in FIG14 , an inductively coupled plasma (ICP) can be used to form a photoresist on the side of the substrate 121 away from the insulating layer. The material of the super surface structure unit 122 on the photoresist is removed by an ICP process. Subsequently, as shown in FIG. 15 , the photoresist can be stripped by a stripping process to prepare a plurality of super surface structure units 122 on the substrate 121. Subsequently, as shown in FIG. 16 , a protective layer 13 can be prepared on the plurality of super surface structure units 122 and in the gaps between the plurality of super surface structure units 122 by a spin coating process, so that the protective layer 13 covers the plurality of super surface structure units 122 and the substrate 121, thereby protecting the super lens structure 12. It can be seen that the superlens structure 12 provided in the embodiment of the present invention can be directly prepared and integrated on the photoelectric conversion structure 11 through a semiconductor process. Therefore, the problem of low integration of the existing pixel unit 1 due to the need to bond the curved lens to the photoelectric conversion structure 11 can be avoided, and there is no need to bond the color filter and the curved lens, thereby improving the integration of the pixel unit 1, and improving color deviation and chromatic aberration, thereby reducing the volume of the image sensor and the spectrometer 2, and improving the imaging effects of the image sensor and the spectrometer 2, such as imaging light intensity, imaging resolution, etc.

However, the structure of the pixel unit 1 provided in the embodiment of the present invention is not limited thereto. Moreover, the manufacturing process of the pixel unit 1 provided in the embodiment of the present invention is not limited thereto.

An embodiment of the present invention also provides an image sensor, comprising at least three pixel units 1 as provided in the embodiment of the present invention, wherein the at least three pixel units 1 are distributed in an array, and the at least three pixel units 1 are capable of at least respectively screening out red light, green light and blue light from a light image, and respectively focusing the red light, green light and blue light, and respectively generating currents corresponding to the red light, green light and blue light.

The image sensor provided by the embodiment of the present invention uses at least three pixel units 1 provided by the embodiment of the present invention to respectively filter out red light, green light and blue light from the light image, and respectively focus the red light, green light and blue light, and respectively generate currents corresponding to the red light, green light and blue light, thereby reducing the volume of the image sensor and the spectrometer 2 and improving the imaging effect.

For example, the image sensor may include four pixel units 1 provided in the embodiment of the present invention, and the four pixel units 1 may form a 2*2 array distribution, and one of the four pixel units 1 may be able to filter out red light from the light image, focus the red light, and generate a current corresponding to the red light, one pixel unit 1 may be able to filter out blue light from the light image, focus the blue light, and generate a current corresponding to the blue light, and two pixel units 1 may be able to filter out green light from the light image, focus the green light, and generate a current corresponding to the green light. However, the distribution method of the four pixel units 1 is not limited to this.

Of course, the image sensor may include three pixel units 1 as provided in the embodiment of the present invention, among which one pixel unit 1 may be able to filter out red light from the light image, focus the red light, and generate a current corresponding to the red light, one pixel unit 1 may be able to filter out blue light from the light image, focus the blue light, and generate a current corresponding to the blue light, and one pixel unit 1 may be able to filter out green light from the light image, focus the green light, and generate a current corresponding to the green light.

An embodiment of the present invention also provides a spectrometer 2, comprising a plurality of pixel units 1 as provided in the embodiment of the present invention, wherein the plurality of pixel units 1 are distributed in an array, and the plurality of pixel units 1 are at least capable of respectively screening out visible light of different wavelengths from the light image, and respectively focusing the visible light of different wavelengths, and generating currents corresponding to the visible light of different wavelengths.

The spectrometer 2 provided by the embodiment of the present invention uses multiple pixel units 1 provided by the embodiment of the present invention to filter out visible light of different wavelengths from the light image, focus the visible light of different wavelengths, and generate current corresponding to the visible light of different wavelengths, thereby reducing the volume of the spectrometer 2 and improving the imaging effect.

As shown in FIG. 17 and FIG. 18 , for example, the spectrometer 2 may include 48 pixel units 1 provided in the embodiment of the present invention, and the 48 pixel units 1 may form a 6*8 array distribution. In this case, the visible light interval with a wavelength of 400nm-700nm may be evenly divided into 48 wavelengths of visible light. The 48 pixel units 1 respectively screen out 48 wavelengths of visible light from the light image, and respectively focus the 48 wavelengths of visible light, and generate current corresponding to the 48 wavelengths of visible light, so that the spectrometer 2 can perform spectrum extraction in the visible light range of 400nm-700nm, thereby improving the sensitivity of the spectrometer 2. However, the number of pixel units 1 included in the spectrometer 2 is not limited thereto, and the selection range of visible light and the division of visible light are not limited thereto.

In summary, the pixel unit 1, image sensor and spectrometer 2 provided by the embodiments of the present invention can improve the integration of the pixel unit 1 and improve color shift and chromatic aberration, thereby reducing the volume of the image sensor and spectrometer 2 and improving the imaging effect.

It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims (8)

1. A pixel unit, characterized in that it includes a photoelectric conversion structure and a super lens structure, wherein the photoelectric conversion structure can generate current under light; the super lens structure is arranged on the photoelectric conversion structure, and the super lens structure can filter out light of a preset wavelength from the light image and focus the light of the preset wavelength on the photoelectric conversion structure; the super lens structure includes a light-transmitting substrate and a plurality of super surface structure units, wherein the substrate is arranged on the photoelectric conversion structure, and the plurality of super surface structure units are all arranged on a side surface of the substrate away from the photoelectric conversion structure and are distributed in an array, and the length of each of the super surface structure units in the vertical direction is less than the preset wavelength; The shape of each of the super-surface structure units is a rectangular cylinder, the long axis of each of the super-surface structure units is parallel to a side of the substrate away from the photoelectric conversion structure, and the long axis of each of the super-surface structure units has a preset angle with a first preset direction, the first preset direction is parallel to a side of the substrate away from the photoelectric conversion structure, so that the plurality of super-surface structure units cooperate to focus the light of the preset wavelength on the photoelectric conversion structure; the shape of the side of the substrate away from the photoelectric conversion structure is square, the side of the substrate away from the photoelectric conversion structure is divided into a plurality of square sub-surfaces, the number of the sub-surfaces is the same as the number of the super-surface structure units, the plurality of super-surface structure units are arranged one by one on the plurality of sub-surfaces, and the preset degree of the angle between the long axis of each of the super-surface structure units and the first preset direction is obtained by the following formula: Among them, θ is the angle of the preset degree between the long axis of the supersurface structure unit and the first preset direction, π is the pi, λ is the preset wavelength, f is the focal length, x is the position coordinate of the side of the substrate away from the photoelectric conversion structure in the first preset direction, y is the position coordinate of the side of the substrate away from the photoelectric conversion structure in the second preset direction perpendicular to the first preset direction, and s is the side length of the side of the substrate away from the photoelectric conversion structure. 2. The pixel unit according to claim 1, characterized in that the material used to make each of the super-surface structure units comprises any one of a-Si, p-Si, Si ₃ N ₄ and TiO ₂ . 3. The pixel unit according to claim 1 is characterized in that the photoelectric conversion structure includes a photoelectric conversion metal part, a substrate and a light-transmitting insulating layer, wherein the insulating layer is arranged on the substrate, the photoelectric conversion metal part is arranged in the insulating layer, the photoelectric conversion metal part can generate current under light, and the super lens structure is arranged on a side surface of the insulating layer away from the substrate. 4 . The pixel unit according to claim 3 , wherein the number of the photoelectric conversion metal parts is plural, and the plurality of the photoelectric conversion metal parts are arranged in the insulating layer at intervals. 5. The pixel unit according to claim 1 is characterized in that the pixel unit also includes a light-transmitting protective layer, which covers a side surface of the super lens structure away from the photoelectric conversion structure to protect the super lens structure. 6 . The pixel unit according to claim 5 , wherein the protective layer is made of a material comprising polymethyl methacrylate or polydimethylsiloxane. 7. An image sensor, characterized in that it comprises at least three pixel units as described in any one of claims 1 to 6, wherein the at least three pixel units are distributed in an array, and the at least three pixel units are capable of at least respectively screening out red light, green light and blue light from a light image, and respectively focusing the red light, green light and blue light, and respectively generating currents corresponding to the red light, green light and blue light. 8. A spectrometer, characterized in that it comprises a plurality of pixel units according to any one of claims 1 to 6, wherein the plurality of pixel units are distributed in an array, and the plurality of pixel units are at least capable of respectively screening out visible light of different wavelengths from a light image, respectively focusing the visible light of different wavelengths, and generating currents corresponding to the visible light of different wavelengths.