Image sensor and manufacturing method thereof

Abstract

The invention provides an image sensor and a manufacturing method thereof. The image sensor comprises a substrate; the light filtering layer is formed on the substrate and comprises a first light-transmitting material layer and a second light-transmitting material layer, the first light-transmitting material layer is closer to the substrate than the second light-transmitting material layer, and the refractive index of the second light-transmitting material layer is larger than that of the first light-transmitting material layer; the light filtering layer comprises a first area, a second area, a third area and a fourth area which are adjacent in pairs in sequence, the light filtering layers located in the first area, the second area, the third area and the fourth area have different optical thicknesses, and the first area allows light rays of other colors except the light rays of the first color in the mixed color light rays to pass through; the second area or the fourth area allows other color light rays except the second color light rays in the mixed color light rays to pass through, and the third area allows other color light rays except the third color light rays in the mixed color light rays to pass through. According to the technical scheme, the quantum efficiency is improved.

Description

Technical Field

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

[0002] At present, all CMOS image sensors use R, G, and B organic materials as filter layers to achieve color distinction between different pixel units, and then combine the data of adjacent pixel units through algorithms to achieve color restoration, which is commonly known as the Bayer Pattern. A single-color filter layer only transmits a single color of light and absorbs light of other colors, resulting in more photon loss.

[0003] Therefore, how to reduce the loss of photons to improve quantum efficiency is an urgent problem that needs to be solved. Summary of the invention

[0004] The object of the present invention is to provide an image sensor and a method for manufacturing the same, so that the quantum efficiency is improved.

[0005] To achieve the above object, the present invention provides an image sensor, comprising:

[0006] substrate;

[0007] A filter layer is formed on the substrate, the filter layer includes a first light-transmitting material layer and a second light-transmitting material layer, the first light-transmitting material layer is closer to the substrate than the second light-transmitting material layer, the refractive index of the second light-transmitting material layer is greater than the refractive index of the first light-transmitting material layer, the filter layer includes a first area, a second area, a third area, and a fourth area, the first area, the second area, the third area, and the fourth area are adjacent to each other in sequence, the filter layers located in the first area, the second area, the third area, and the fourth area have different optical thicknesses, the first area allows other color light except the first color light in the mixed color light to pass through, the second area or the fourth area allows other color light except the second color light in the mixed color light to pass through, and the third area allows other color light except the third color light in the mixed color light to pass through.

[0008] Optionally, the physical thicknesses of the second light-transmitting material layer in the first region and the third region are λ1 / (4*n1) and λ3 / (4*n1) respectively, and the physical thickness of the second region or the fourth region is λ2 / (4*n1); λ1, λ2 and λ3 are the wavelengths of the first color light, the second color light and the third color light respectively, and n1 is the refractive index of the second light-transmitting material layer.

[0009] Optionally, the filter layer includes the first light-transmitting material layer and the second light-transmitting material layer that are periodically alternately stacked, the first light-transmitting material layer in each period is closer to the substrate than the second light-transmitting material layer, and the number of periods of the periodic alternate stacking is greater than or equal to 3.

[0010] Optionally, the material of the first light-transmitting material layer includes silicon oxide, and the material of the second light-transmitting material layer includes silicon nitride.

[0011] Optionally, the image sensor further includes:

[0012] A metal grid is formed on the substrate, and the metal grid is used to isolate the first region, the second region, the third region, and the fourth region from each other.

[0013] Optionally, the image sensor further includes:

[0014] A pixel array is arranged in the substrate, pixels in the pixel array are formed correspondingly below the first area, the second area, the third area, and the fourth area, and adjacent pixels are isolated by an isolation structure.

[0015] Optionally,

[0016] The first area allows other color lights except the first color light in the mixed color light to pass through so that the pixels below the first area can calculate and output the complementary color of the first color light through an algorithm;

[0017] The second area or the fourth area allows other color lights except the second color light in the mixed color light to pass through so that the pixels under the second area and the fourth area can calculate and output the complementary color of the second color light through an algorithm;

[0018] The third area allows other color lights except the third color light in the mixed color light to pass through so that the pixels below the third area can output the complementary color of the third color light through algorithm calculation.

[0019] The present invention also provides a method for manufacturing an image sensor, comprising:

[0020] providing a substrate;

[0021] A filter layer is formed on the substrate, the filter layer includes a first light-transmitting material layer and a second light-transmitting material layer, the first light-transmitting material layer is closer to the substrate than the second light-transmitting material layer, the refractive index of the second light-transmitting material layer is greater than the refractive index of the first light-transmitting material layer, the filter layer includes a first region, a second region, a third region, and a fourth region, the first region, the second region, the third region, and the fourth region are adjacent to each other in sequence, the filter layers located in the first region, the second region, the third region, and the fourth region have different optical thicknesses, the first region allows other color light except the first color light in the mixed color light to pass through, the second region or the fourth region allows other color light except the second color light in the mixed color light to pass through, and the third region allows other color light except the third color light in the mixed color light to pass through.

[0022] Optionally, the physical thicknesses of the second light-transmitting material layer in the first region and the third region are λ1 / (4*n1) and λ3 / (4*n1) respectively, and the physical thickness of the second region or the fourth region is λ2 / (4*n1); λ1, λ2 and λ3 are the wavelengths of the first color light, the second color light and the third color light respectively, and n1 is the refractive index of the second light-transmitting material layer.

[0023] Optionally, the filter layer includes the first light-transmitting material layer and the second light-transmitting material layer that are periodically alternately stacked, the first light-transmitting material layer in each period is closer to the substrate than the second light-transmitting material layer, and the number of periods of the periodic alternate stacking is greater than or equal to 3.

[0024] Optionally, the material of the first light-transmitting material layer includes silicon oxide, and the material of the second light-transmitting material layer includes silicon nitride.

[0025] Optionally, the method for manufacturing the image sensor further includes:

[0026] A metal grid is formed on the substrate, and the metal grid is used to isolate the first region, the second region, the third region, and the fourth region from each other.

[0027] Optionally, before forming the filter layer on the substrate, the method for manufacturing the image sensor further includes:

[0028] A pixel array is formed, and the array is arranged in the substrate. Pixels in the pixel array are correspondingly formed below the first area, the second area, the third area, and the fourth area, and adjacent pixels are isolated by an isolation structure.

[0029] Optionally,

[0030] The first area allows other color lights except the first color light in the mixed color light to pass through so that the pixels below the first area can calculate and output the complementary color of the first color light through an algorithm;

[0031] The second area or the fourth area allows other color lights except the second color light in the mixed color light to pass through so that the pixels under the second area and the fourth area can calculate and output the complementary color of the second color light through an algorithm;

[0032] The third area allows other color lights except the third color light in the mixed color light to pass through so that the pixels below the third area can output the complementary color of the third color light through algorithm calculation.

[0033] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0034] 1. The image sensor of the present invention comprises: a substrate; a filter layer formed on the substrate, the filter layer comprises a first light-transmitting material layer and a second light-transmitting material layer, the first light-transmitting material layer is closer to the substrate than the second light-transmitting material layer, the refractive index of the second light-transmitting material layer is greater than the refractive index of the first light-transmitting material layer, the filter layer comprises a first region, a second region, a third region, and a fourth region, the first region, the second region, the third region, and the fourth region are adjacent to each other in sequence, the filter layers located in the first region, the second region, the third region, and the fourth region have different optical thicknesses, the first region allows other color light except the first color light in the mixed color light to pass through, the second region or the fourth region allows other color light except the second color light in the mixed color light to pass through, and the third region allows other color light except the third color light in the mixed color light to pass through, so that the quantum efficiency is improved.

[0035] 2. A method for manufacturing an image sensor of the present invention comprises forming a filter layer on the substrate, the filter layer comprising a first light-transmitting material layer and a second light-transmitting material layer, the first light-transmitting material layer being closer to the substrate than the second light-transmitting material layer, the refractive index of the second light-transmitting material layer being greater than the refractive index of the first light-transmitting material layer, the filter layer comprising a first region, a second region, a third region, and a fourth region, the first region, the second region, the third region, and the fourth region being adjacent to each other in sequence, the filter layers located in the first region, the second region, the third region, and the fourth region have different optical thicknesses, the first region allows other color light rays except the first color light rays in the mixed color light rays to pass through, the second region or the fourth region allows other color light rays except the second color light rays in the mixed color light rays to pass through, and the third region allows other color light rays except the third color light rays in the mixed color light rays to pass through, so that the quantum efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a schematic top view of an image sensor according to an embodiment of the present invention;

[0037] Figure 2 yes Figure 1 The image sensor is shown as a cross-sectional schematic diagram along the AA' direction;

[0038] Figure 3 yes Figure 1 The image sensor is shown as a cross-sectional schematic diagram along the BB' direction;

[0039] Figure 4 is a schematic diagram of enhancing reflection of a filter layer according to an embodiment of the present invention;

[0040] Figure 5 is a flow chart of a method for manufacturing an image sensor according to an embodiment of the present invention.

[0041] Among them, Figure 1 to Figure 5 The reference numerals are described as follows:

[0042] 10 - substrate; 11 - first light-transmitting material layer; 12 - second light-transmitting material layer; 13 - metal grid. DETAILED DESCRIPTION

[0043] In order to make the purpose, advantages and features of the present invention more clear, the image sensor and the manufacturing method thereof proposed by the present invention are further described in detail below in conjunction with the accompanying drawings. It should be noted that the accompanying drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0044] An embodiment of the present invention provides an image sensor, comprising: a substrate; a filter layer formed on the substrate, the filter layer comprising a first light-transmitting material layer and a second light-transmitting material layer, the first light-transmitting material layer being closer to the substrate than the second light-transmitting material layer, the refractive index of the second light-transmitting material layer being greater than the refractive index of the first light-transmitting material layer, the filter layer comprising a first region, a second region, a third region, and a fourth region, the first region, the second region, the third region, and the fourth region being adjacent to each other in sequence, the filter layers located in the first region, the second region, the third region, and the fourth region have different optical thicknesses, the first region allows other color light rays except the first color light rays in a mixed color light to pass through, the second region or the fourth region allows other color light rays except the second color light rays in the mixed color light to pass through, and the third region allows other color light rays except the third color light in the mixed color light to pass through.

[0045] See below Figure 1 to Figure 4 The image sensor provided by this embodiment is described in more detail.

[0046] The substrate 10 may be a wafer or a chip, and device structures such as MOS transistors, resistors, and capacitors may be formed in the substrate 10 .

[0047] The material or device function of the substrate 10 is not limited here.

[0048] The filter layer is formed on the substrate 10, and the filter layer includes a first light-transmitting material layer 11 and a second light-transmitting material layer 12. The first light-transmitting material layer 11 is closer to the substrate 10 than the second light-transmitting material layer 12. The refractive index of the second light-transmitting material layer 12 is greater than the refractive index of the first light-transmitting material layer 11. The filter layer includes a first area A1, a second area A2, a third area A3, and a fourth area A4. The first area A1, the second area A2, the third area A3, and the fourth area A4 are adjacent to each other in sequence. The filter layers located in the first area A1, the second area A2, the third area A3, and the fourth area A4 have different optical thicknesses. The first area A1 allows other color light rays except the first color light ray in the mixed color light to pass through. The second area A2 or the fourth area A4 allows other color light rays except the second color light ray in the mixed color light to pass through. The third area A3 allows other color light rays except the third color light in the mixed color light to pass through.

[0049] The mixed color light includes at least three color lights. In one embodiment, the mixed color light is, for example, white light.

[0050] The image sensor also includes a pixel array, which is arranged in the substrate 10. Pixels in the pixel array are correspondingly formed below the first area A1, the second area A2, the third area A3, and the fourth area A4, and adjacent pixels are isolated by an isolation structure (not shown).

[0051] The pixel includes a photosensitive device (eg, a photodiode) for converting absorbed photons into electrical signals.

[0052] The isolation structure may be a deep trench isolation structure extending from the surface of the substrate 10 into the substrate 10 ; the material of the isolation structure may be at least one of insulating materials such as silicon oxide, silicon oxynitride and silicon nitride.

[0053] By adjusting the optical thickness of the filter layer of the first area A1, the first area A1 can allow other color lights except the first color light in the mixed color light to pass through, so that the pixels below the first area A1 can output the complementary color of the first color light through algorithm calculation; by adjusting the optical thickness of the filter layer of the second area A2 or the fourth area A4, the second area A2 or the fourth area A4 can allow other color lights except the second color light in the mixed color light to pass through, so that the pixels below the second area A2 or the fourth area A4 can output the complementary color of the second color light through algorithm calculation; by adjusting the optical thickness of the filter layer of the third area A3, the third area A3 can allow other color lights except the third color light in the mixed color light to pass through, so that the pixels below the third area A3 can output the complementary color of the third color light through algorithm calculation.

[0054] In one embodiment, adjusting the optical thickness of the filter layer of the first area A1, the second area A2, the third area A3, and the fourth area A4 includes adjusting the optical thickness of the second light-transmitting material layer 12 of the first area A1, the second area A2, the third area A3, and the fourth area A4, so that the filter layer of the first area A1 enhances the reflection of the first color light in the direction away from the substrate 10, the filter layer of the second area A2 or the fourth area A4 enhances the reflection of the second color light in the direction away from the substrate 10, and the filter layer of the third area A3 enhances the reflection of the third color light in the direction away from the substrate 10, so that the filter layer of the first area A1 prevents the first color light in the mixed color light from passing through, the filter layer of the second area A2 or the fourth area A4 prevents the second color light in the mixed color light from passing through, and the filter layer of the third area A3 prevents the third color light in the mixed color light from passing through.

[0055] In one embodiment, the first color light is red light, that is, when the mixed color light is incident on the filter layer of the first area A1, the red light is reflected by the filter layer (that is, the filter layer prevents the red light from passing through), and the other color lights except the red light in the mixed color light pass through the filter layer of the first area A1 and enter the pixel, so that the pixel below the first area A1 outputs the complementary color of red (that is, cyan) through the algorithm calculation data; the second color light is green light, that is, when the mixed color light is incident on the filter layer of the second area A2 or the fourth area A4, the green light is reflected by the filter layer (that is, the filter layer prevents the green light from passing through), and the green light in the mixed color light is The other color lights except the blue light in the mixed color light pass through the filter layer of the second area A2 or the fourth area A4 and enter the pixel, so that the pixel below the second area A2 or the fourth area A4 is output as the complementary color of green (i.e. magenta) through the algorithm calculation data; the third color light is blue light, that is, when the mixed color light enters the filter layer of the third area A3, the blue light is reflected by the filter layer (i.e., the filter layer prevents the blue light from passing through), and the other color lights except the blue light in the mixed color light pass through the filter layer of the third area A3 and enter the pixel, so that the pixel below the third area A3 is output as the complementary color of blue (i.e. yellow) through the algorithm calculation data.

[0056] In one embodiment, taking the first color light as red light, the second color light as green light, and the third color light as blue light as an example, for the traditional Bayer model Pattern), the red filter layer, the green filter layer and the blue filter layer only transmit red light, green light and blue light respectively, so that the pixels below the filter layer display red, green and blue, and then the color restoration is realized by combining the data of adjacent pixels through algorithm calculation, for example, the pixel below the green filter layer is fitted by the algorithm according to the data of the pixels below the adjacent red filter layer and the blue filter layer; in the present invention, the filter layer of the first area A1 transmits the superposition of green light and blue light, the filter layer of the second area A2 or the fourth area A4 transmits the superposition of red light and blue light, and the filter layer of the third area A3 transmits the superposition of green light and red light, that is, the light transmitted by the filter layer above each pixel is only the superposition of two colors, then, the color restoration can also be realized by combining the data of adjacent pixels through the algorithm, for example, the pixel below the second area A2 or the fourth area A4 can also be fitted by the algorithm according to the data of the pixels below the adjacent first area A1 and the pixels below the third area A3, and then the complementary color of green (i.e. magenta) is output.

[0057] The principles of enhancing the reflection of a certain color of light include: Figure 4As shown, when incident light L1 of a certain wavelength (i.e., a certain color) is incident from the air to the upper surface B1 of the second light-transmitting material layer 12, reflection and refraction will occur on the upper surface B1 of the second light-transmitting material layer 12 to obtain reflected light L2 and refracted light respectively. The reflected light L2 returns to the air in a direction away from the substrate 10, and the refracted light will also be reflected on the lower surface B2 of the second light-transmitting material layer 12, and refracted by the upper surface B1 of the second light-transmitting material layer 12 to obtain refracted light L3. The refracted light L3 returns to the air in a direction away from the substrate 10. When light is emitted from an optically sparse medium to an optically dense medium (the refractive index of the optically sparse medium is smaller than that of the optically denser medium), the reflected light has a half-wave loss, and the refractive index of air is smaller than that of the second light-transmitting material layer 12, and the refractive index of the second light-transmitting material layer 12 is larger than the refractive index of the first light-transmitting material layer 11. Therefore, only the reflection of light on the upper surface B1 of the second light-transmitting material layer 12 has a half-wave loss, and the reflection of light on the lower surface B2 of the second light-transmitting material layer 12 has no half-wave loss, so that the optical path difference of the light reflected twice on the upper surface B1 and the lower surface B2 of the second light-transmitting material layer 12 is d=2*n1*h+λ / 2 (wherein n1 is the refractive index of the second light-transmitting material layer 12, h is the physical thickness of the second light-transmitting material layer 12, and λ is the wavelength of the light reflected twice by the filter layer in the direction away from the substrate 10). Moreover, when the optical path difference of the light reflected twice by the filter layer in the direction away from the substrate 10 is equal to an integer multiple of the wavelength, the interference of the light returned to the air after the two reflections will be enhanced, thereby increasing the energy of the light reflected into the air by the second light-transmitting material layer 12 as a whole, thereby achieving enhanced reflection of light of a certain color in the direction away from the substrate 10.

[0058] The optical path difference of the light reflected twice by the filter layer in the direction away from the substrate 10 is equal to an integer multiple of the wavelength, that is, 2*n1*h+λ / 2=k*λ. When k=1, the physical thickness of the second light-transmitting material layer 12 is the thinnest, so that 2*n1*h=λ / 2. Then, the physical thickness of the second light-transmitting material layer 12 can be calculated as h=λ / (4*n1). The optical thickness of the second light-transmitting material layer 12 is the product of the physical thickness h and the refractive index n1.

[0059] Therefore, when the refractive index of the second light-transmitting material layer 12 is greater than the refractive index of the first light-transmitting material layer 11, by adjusting the optical thickness of the second light-transmitting material layer 12 in each area (i.e., the first area A1, the second area A2, the third area A3, and the fourth area A4), the filter layer in each area can enhance the reflection of light of a specific wavelength (i.e., a certain color) in a direction away from the substrate 10 (i.e., toward the air), thereby improving the reflectivity of light of a specific wavelength, and transmitting other wavelengths of light in the mixed color light, so that the pixels under each area output the complementary color of the light of the specific wavelength.

[0060] The physical thickness of the second light-transmitting material layer 12 in the first area A1 is λ1 / (4*n1), the physical thickness of the second light-transmitting material layer 12 in the second area A2 or the fourth area A4 is λ2 / (4*n1), and the physical thickness of the second light-transmitting material layer 12 in the third area A3 is λ3 / (4*n1); λ1, λ2 and λ3 are the wavelengths of the first color light, the second color light and the third color light respectively.

[0061] When the first color light is red light, the second color light is green light, and the third color light is blue light, due to λ1>λ2>λ3, the physical thickness of the second light-transmitting material layer 12 in the first area A1, the second area A2 (or the fourth area A4) to the third area A3 decreases in sequence, such as Figure 2 and Figure 3 shown.

[0062] The physical thicknesses of the first light-transmitting material layer 11 in the first area A1 , the second area A2 (or the fourth area A4 ), and the third area A3 may be the same or different.

[0063] Preferably, the filter layer includes the first light-transmitting material layer 11 and the second light-transmitting material layer 12 which are periodically and alternately stacked, the first light-transmitting material layer 11 in each period is closer to the substrate 10 than the second light-transmitting material layer 12, and the number of periods of the periodic alternating stacking is greater than or equal to 3, so that the transmission amounts of the first color light, the second color light and the third color light in the filter layer of the first area A1, the second area A2 (or the fourth area A4) and the third area A3, respectively, can be reduced as much as possible, thereby enabling the filter layers of the first area A1, the second area A2 (or the fourth area A4) and the third area A3 to achieve total reflection of the first color light, the second color light and the third color light, respectively.

[0064] In one embodiment, the material of the first light-transmitting material layer 11 includes silicon oxide, and the material of the second light-transmitting material layer 12 includes silicon nitride.

[0065] The image sensor also includes: a metal grid 13 formed on the substrate 10, and the metal grid 13 is used to isolate the first area A1, the second area A2, the third area A3, and the fourth area A4 from each other, that is, the metal grid 13 is located between the filter layers of adjacent areas of the first area A1, the second area A2, the third area A3, and the fourth area A4, and the metal grid 13 is located on the isolation structure between adjacent pixels to avoid optical crosstalk between adjacent pixels.

[0066] It can be seen from the above content that, since the refractive index of the second light-transmitting material layer 12 in the filter layer is greater than the refractive index of the first light-transmitting material layer 11 in the filter layer, the filter layers located in the first area A1, the second area A2, the third area A3, and the fourth area A4 have different optical thicknesses, so that the first area A1 allows other color lights except the first color light in the mixed color light to pass through, the second area A2 or the fourth area A4 allows other color lights except the second color light in the mixed color light to pass through, and the third area A3 allows other color lights except the third color light in the mixed color light to pass through, that is, only one color of the mixed color lights incident on the filter layer of each area is reflected, and the other colors of the mixed color lights incident on the filter layer of each area are all transmitted into the pixel, and each pixel only loses one color of light. Compared with the traditional Bayer model in which the filter layer of each area only transmits one color of light and absorbs other colors of light, the photon transmittance of the image sensor of the present invention is improved, the loss of photons is reduced, and the quantum efficiency is improved.

[0067] In summary, the image sensor provided by the present invention comprises: a substrate; a filter layer formed on the substrate, the filter layer comprises a first light-transmitting material layer and a second light-transmitting material layer, the first light-transmitting material layer is closer to the substrate than the second light-transmitting material layer, the refractive index of the second light-transmitting material layer is greater than the refractive index of the first light-transmitting material layer, the filter layer comprises a first region, a second region, a third region, and a fourth region, the first region, the second region, the third region, and the fourth region are adjacent to each other in sequence, the filter layers located in the first region, the second region, the third region, and the fourth region have different optical thicknesses, the first region allows other color lights except the first color light in the mixed color light to pass through, the second region or the fourth region allows other color lights except the second color light in the mixed color light to pass through, and the third region allows other color lights except the third color light in the mixed color light to pass through. The image sensor of the present invention improves quantum efficiency.

[0068] An embodiment of the present invention provides a method for manufacturing an image sensor. Figure 5 , Figure 5 1 is a flow chart of a method for manufacturing an image sensor according to an embodiment of the present invention, wherein the method for manufacturing an image sensor comprises:

[0069] Step S1, providing a substrate;

[0070] Step S2, forming a filter layer on the substrate, the filter layer comprising a first light-transmitting material layer and a second light-transmitting material layer, the first light-transmitting material layer is closer to the substrate than the second light-transmitting material layer, the refractive index of the second light-transmitting material layer is greater than the refractive index of the first light-transmitting material layer, the filter layer comprising a first region, a second region, a third region, and a fourth region, the first region, the second region, the third region, and the fourth region are adjacent to each other in sequence, the filter layers located in the first region, the second region, the third region, and the fourth region have different optical thicknesses, the first region allows other color light rays except the first color light ray in the mixed color light to pass through, the second region or the fourth region allows other color light rays except the second color light in the mixed color light to pass through, and the third region allows other color light rays except the third color light in the mixed color light to pass through.

[0071] See below Figure 1 to Figure 4 The manufacturing method of the image sensor provided in this embodiment is introduced in more detail.

[0072] According to step S1 , a substrate 10 is provided.

[0073] The substrate 10 may be a wafer or a chip, and device structures such as MOS transistors, resistors, and capacitors may be formed in the substrate 10 .

[0074] The material or device function of the substrate 10 is not limited here.

[0075] According to step S2, a filter layer is formed on the substrate 10, the filter layer includes a first light-transmitting material layer 11 and a second light-transmitting material layer 12, the first light-transmitting material layer 11 is closer to the substrate 10 than the second light-transmitting material layer 12, the refractive index of the second light-transmitting material layer 12 is greater than the refractive index of the first light-transmitting material layer 11, the filter layer includes a first area A1, a second area A2, a third area A3, and a fourth area A4, the first area A1, the second area A2, the third area A3, and the fourth area A4 are adjacent to each other in sequence, the filter layers located in the first area A1, the second area A2, the third area A3, and the fourth area A4 have different optical thicknesses, the first area A1 allows other color light rays except the first color light ray in the mixed color light to pass through, the second area A2 or the fourth area A4 allows other color light rays except the second color light ray in the mixed color light to pass through, and the third area A3 allows other color light rays except the third color light in the mixed color light to pass through.

[0076] The mixed color light includes at least three color lights. In one embodiment, the mixed color light is, for example, white light.

[0077] Before forming the filter layer on the substrate 10, the manufacturing method of the image sensor also includes: forming a pixel array, the array is arranged in the substrate 10, and pixels in the pixel array are correspondingly formed below the first area A1, the second area A2, the third area A3, and the fourth area A4, and adjacent pixels are isolated by an isolation structure (not shown).

[0078] The pixel includes a photosensitive device (eg, a photodiode) for converting absorbed photons into electrical signals.

[0079] The isolation structure may be a deep trench isolation structure extending from the surface of the substrate 10 into the substrate 10 ; the material of the isolation structure may be at least one of insulating materials such as silicon oxide, silicon oxynitride and silicon nitride.

[0080] By adjusting the optical thickness of the filter layer of the first area A1, the first area A1 can allow other color lights except the first color light in the mixed color light to pass through, so that the pixels below the first area A1 can output the complementary color of the first color light through algorithm calculation; by adjusting the optical thickness of the filter layer of the second area A2 or the fourth area A4, the second area A2 or the fourth area A4 can allow other color lights except the second color light in the mixed color light to pass through, so that the pixels below the second area A2 or the fourth area A4 can output the complementary color of the second color light through algorithm calculation; by adjusting the optical thickness of the filter layer of the third area A3, the third area A3 can allow other color lights except the third color light in the mixed color light to pass through, so that the pixels below the third area A3 can output the complementary color of the third color light through algorithm calculation.

[0081] In one embodiment, adjusting the optical thickness of the filter layer of the first area A1, the second area A2, the third area A3, and the fourth area A4 includes adjusting the optical thickness of the second light-transmitting material layer 12 of the first area A1, the second area A2, the third area A3, and the fourth area A4, so that the filter layer of the first area A1 enhances the reflection of the first color light in the direction away from the substrate 10, the filter layer of the second area A2 or the fourth area A4 enhances the reflection of the second color light in the direction away from the substrate 10, and the filter layer of the third area A3 enhances the reflection of the third color light in the direction away from the substrate 10, so that the filter layer of the first area A1 prevents the first color light in the mixed color light from passing through, the filter layer of the second area A2 or the fourth area A4 prevents the second color light in the mixed color light from passing through, and the filter layer of the third area A3 prevents the third color light in the mixed color light from passing through.

[0082] In one embodiment, the first color light is red light, that is, when the mixed color light is incident on the filter layer of the first area A1, the red light is reflected by the filter layer (that is, the filter layer prevents the red light from passing through), and the other color lights except the red light in the mixed color light pass through the filter layer of the first area A1 and enter the pixel, so that the pixel below the first area A1 outputs the complementary color of red (that is, cyan) through the algorithm calculation data; the second color light is green light, that is, when the mixed color light is incident on the filter layer of the second area A2 or the fourth area A4, the green light is reflected by the filter layer (that is, the filter layer prevents the green light from passing through), and the green light in the mixed color light is The other color lights except the blue light in the mixed color light pass through the filter layer of the second area A2 or the fourth area A4 and enter the pixel, so that the pixel below the second area A2 or the fourth area A4 is output as the complementary color of green (i.e. magenta) through the algorithm calculation data; the third color light is blue light, that is, when the mixed color light enters the filter layer of the third area A3, the blue light is reflected by the filter layer (i.e., the filter layer prevents the blue light from passing through), and the other color lights except the blue light in the mixed color light pass through the filter layer of the third area A3 and enter the pixel, so that the pixel below the third area A3 is output as the complementary color of blue (i.e. yellow) through the algorithm calculation data.

[0083] In one embodiment, taking the first color light as red light, the second color light as green light, and the third color light as blue light as an example, for the traditional Bayer model Pattern), the red filter layer, the green filter layer and the blue filter layer only transmit red light, green light and blue light respectively, so that the pixels below the filter layer display red, green and blue, and then the color restoration is realized by combining the data of adjacent pixels through algorithm calculation, for example, the pixel below the green filter layer is fitted by the algorithm according to the data of the pixels below the adjacent red filter layer and the blue filter layer; in the present invention, the filter layer of the first area A1 transmits the superposition of green light and blue light, the filter layer of the second area A2 or the fourth area A4 transmits the superposition of red light and blue light, and the filter layer of the third area A3 transmits the superposition of green light and red light, that is, the light transmitted by the filter layer above each pixel is only the superposition of two colors, then, the color restoration can also be realized by combining the data of adjacent pixels through the algorithm, for example, the pixel below the second area A2 or the fourth area A4 can also be fitted by the algorithm according to the data of the pixels below the adjacent first area A1 and the pixels below the third area A3, and then the complementary color of green (i.e. magenta) is output.

[0084] The principles of enhancing the reflection of a certain color of light include: Figure 4As shown, when incident light L1 of a certain wavelength (i.e., a certain color) is incident from the air to the upper surface B1 of the second light-transmitting material layer 12, reflection and refraction will occur on the upper surface B1 of the second light-transmitting material layer 12 to obtain reflected light L2 and refracted light respectively. The reflected light L2 returns to the air in a direction away from the substrate 10, and the refracted light will also be reflected on the lower surface B2 of the second light-transmitting material layer 12, and refracted by the upper surface B1 of the second light-transmitting material layer 12 to obtain refracted light L3. The refracted light L3 returns to the air in a direction away from the substrate 10. When light is emitted from an optically sparse medium to an optically dense medium (the refractive index of the optically sparse medium is smaller than that of the optically denser medium), the reflected light has a half-wave loss, and the refractive index of air is smaller than that of the second light-transmitting material layer 12, and the refractive index of the second light-transmitting material layer 12 is larger than the refractive index of the first light-transmitting material layer 11. Therefore, only the reflection of light on the upper surface B1 of the second light-transmitting material layer 12 has a half-wave loss, and the reflection of light on the lower surface B2 of the second light-transmitting material layer 12 has no half-wave loss, so that the optical path difference of the light reflected twice on the upper surface B1 and the lower surface B2 of the second light-transmitting material layer 12 is d=2*n1*h+λ / 2 (wherein n1 is the refractive index of the second light-transmitting material layer 12, h is the physical thickness of the second light-transmitting material layer 12, and λ is the wavelength of the light reflected twice by the filter layer in the direction away from the substrate 10). Moreover, when the optical path difference of the light reflected twice by the filter layer in the direction away from the substrate 10 is equal to an integer multiple of the wavelength, the interference of the light returned to the air after the two reflections will be enhanced, thereby increasing the energy of the light reflected into the air by the second light-transmitting material layer 12 as a whole, thereby achieving enhanced reflection of light of a certain color in the direction away from the substrate 10.

[0085] The optical path difference of the light reflected twice by the filter layer in the direction away from the substrate 10 is equal to an integer multiple of the wavelength, that is, 2*n1*h+λ / 2=k*λ. When k=1, the physical thickness of the second light-transmitting material layer 12 is the thinnest, so that 2*n1*h=λ / 2. Then, the physical thickness of the second light-transmitting material layer 12 can be calculated as h=λ / (4*n1). The optical thickness of the second light-transmitting material layer 12 is the product of the physical thickness h and the refractive index n1.

[0086] Therefore, when the refractive index of the second light-transmitting material layer 12 is greater than the refractive index of the first light-transmitting material layer 11, by adjusting the optical thickness of the second light-transmitting material layer 12 in each area (i.e., the first area A1, the second area A2, the third area A3, and the fourth area A4), the filter layer in each area can enhance the reflection of light of a specific wavelength (i.e., a certain color) in a direction away from the substrate 10 (i.e., toward the air), thereby improving the reflectivity of light of a specific wavelength, and transmitting other wavelengths of light in the mixed color light, so that the pixels under each area output the complementary color of the light of the specific wavelength.

[0087] The physical thickness of the second light-transmitting material layer 12 in the first area A1 is λ1 / (4*n1), the physical thickness of the second light-transmitting material layer 12 in the second area A2 or the fourth area A4 is λ2 / (4*n1), and the physical thickness of the second light-transmitting material layer 12 in the third area A3 is λ3 / (4*n1); λ1, λ2 and λ3 are the wavelengths of the first color light, the second color light and the third color light respectively.

[0088] When the first color light is red light, the second color light is green light, and the third color light is blue light, due to λ1>λ2>λ3, the physical thickness of the second light-transmitting material layer 12 in the first area A1, the second area A2 (or the fourth area A4) to the third area A3 decreases in sequence, such as Figure 2 and Figure 3 shown.

[0089] The physical thicknesses of the first light-transmitting material layer 11 in the first area A1, the second area A2 or the fourth area A4, and the third area A3 may be the same or different.

[0090] Preferably, the filter layer includes the first light-transmitting material layer 11 and the second light-transmitting material layer 12 which are periodically and alternately stacked, the first light-transmitting material layer 11 in each period is closer to the substrate 10 than the second light-transmitting material layer 12, and the number of periods of the periodic alternating stacking is greater than or equal to 3, so that the transmission amounts of the first color light, the second color light and the third color light in the filter layer of the first area A1, the second area A2 (or the fourth area A4) and the third area A3, respectively, can be reduced as much as possible, thereby enabling the filter layers of the first area A1, the second area A2 (or the fourth area A4) and the third area A3 to achieve total reflection of the first color light, the second color light and the third color light, respectively.

[0091] In one embodiment, the material of the first light-transmitting material layer 11 includes silicon oxide, and the material of the second light-transmitting material layer 12 includes silicon nitride.

[0092] The method for manufacturing the image sensor further includes:

[0093] A metal grid 13 is formed on the substrate 10, and the metal grid 13 is used to isolate the first area A1, the second area A2, the third area A3, and the fourth area A4 from each other, that is, the metal grid 13 is located between the filter layers of adjacent areas among the first area A1, the second area A2, the third area A3, and the fourth area A4, and the metal grid 13 is located on the isolation structure between adjacent pixels to avoid optical crosstalk between adjacent pixels.

[0094] The optical filter layer may be formed first, and then the metal grid 13 may be formed; or the metal grid 13 may be formed first, and then the optical filter layer may be formed.

[0095] The filter layer can be formed by using deposition and etching processes well known to those skilled in the art.

[0096] It can be seen from the above content that, since the refractive index of the second light-transmitting material layer 12 in the filter layer is greater than the refractive index of the first light-transmitting material layer 11 in the filter layer, the filter layers located in the first area A1, the second area A2, the third area A3, and the fourth area A4 have different optical thicknesses, so that the first area A1 allows other color lights except the first color light in the mixed color light to pass through, the second area A2 or the fourth area A4 allows other color lights except the second color light in the mixed color light to pass through, and the third area A3 allows other color lights except the third color light in the mixed color light to pass through, that is, only one color of the mixed color lights incident on the filter layer of each area is reflected, and the other colors of the mixed color lights incident on the filter layer of each area are all transmitted into the pixel, and each pixel only loses one color of light. Compared with the traditional Bayer model in which the filter layer of each area only transmits one color of light and absorbs other colors of light, the photon transmittance of the image sensor of the present invention is improved, the loss of photons is reduced, and the quantum efficiency is improved.

[0097] In summary, the manufacturing method of the image sensor provided by the present invention comprises: providing a substrate; forming a filter layer on the substrate, the filter layer comprising a first light-transmitting material layer and a second light-transmitting material layer, the first light-transmitting material layer is closer to the substrate than the second light-transmitting material layer, the refractive index of the second light-transmitting material layer is greater than the refractive index of the first light-transmitting material layer, the filter layer comprises a first region, a second region, a third region, and a fourth region, the first region, the second region, the third region, and the fourth region are adjacent to each other in sequence, the filter layers located in the first region, the second region, the third region, and the fourth region have different optical thicknesses, the first region allows other color lights except the first color light in the mixed color light to pass through, the second region or the fourth region allows other color lights except the second color light in the mixed color light to pass through, and the third region allows other color lights except the third color light in the mixed color light to pass through. The manufacturing method of the image sensor of the present invention improves quantum efficiency.

[0098] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. An image sensor, characterized in that: include: substrate; A filter layer is formed on the substrate, the filter layer includes a first light-transmitting material layer and a second light-transmitting material layer, the first light-transmitting material layer is closer to the substrate than the second light-transmitting material layer, the refractive index of the second light-transmitting material layer is greater than the refractive index of the first light-transmitting material layer, the filter layer includes a first area, a second area, a third area, and a fourth area, the first area, the second area, the third area, and the fourth area are adjacent to each other in sequence, the filter layers located in the first area, the second area, the third area, and the fourth area have different optical thicknesses, the first area allows other color light except the first color light in the mixed color light to pass through, the second area or the fourth area allows other color light except the second color light in the mixed color light to pass through, and the third area allows other color light except the third color light in the mixed color light to pass through.

2. The image sensor according to claim 1, wherein: The physical thicknesses of the second light-transmitting material layer in the first region and the third region are λ1 / (4*n1) and λ3 / (4*n1) respectively, and the physical thickness of the second region or the fourth region is λ2 / (4*n1); λ1, λ2 and λ3 are the wavelengths of the first color light, the second color light and the third color light respectively, and n1 is the refractive index of the second light-transmitting material layer.

3. The image sensor according to claim 1, wherein: The filter layer includes the first light-transmitting material layer and the second light-transmitting material layer which are periodically and alternately stacked. The first light-transmitting material layer in each period is closer to the substrate than the second light-transmitting material layer. The number of the periodic alternating stacking periods is greater than or equal to 3.

4. The image sensor according to claim 1, wherein: The material of the first light-transmitting material layer includes silicon oxide, and the material of the second light-transmitting material layer includes silicon nitride.

5. The image sensor according to claim 1, wherein: The image sensor further comprises: A metal grid is formed on the substrate, and the metal grid is used to isolate the first region, the second region, the third region, and the fourth region from each other.

6. The image sensor according to claim 1, wherein: The image sensor further comprises: A pixel array is arranged in the substrate, pixels in the pixel array are formed correspondingly below the first area, the second area, the third area, and the fourth area, and adjacent pixels are isolated by an isolation structure.

7. The image sensor according to claim 6, wherein: The first area allows other color lights except the first color light in the mixed color light to pass through so that the pixels below the first area can calculate and output the complementary color of the first color light through an algorithm; The second area or the fourth area allows other color lights except the second color light in the mixed color light to pass through so that the pixels under the second area and the fourth area can calculate and output the complementary color of the second color light through an algorithm; The third area allows other color lights except the third color light in the mixed color light to pass through so that the pixels below the third area can output the complementary color of the third color light through algorithm calculation.

8. A method for manufacturing an image sensor, characterized in that: include: providing a substrate; A filter layer is formed on the substrate, the filter layer includes a first light-transmitting material layer and a second light-transmitting material layer, the first light-transmitting material layer is closer to the substrate than the second light-transmitting material layer, the refractive index of the second light-transmitting material layer is greater than the refractive index of the first light-transmitting material layer, the filter layer includes a first region, a second region, a third region, and a fourth region, the first region, the second region, the third region, and the fourth region are adjacent to each other in sequence, the filter layers located in the first region, the second region, the third region, and the fourth region have different optical thicknesses, the first region allows other color light except the first color light in the mixed color light to pass through, the second region or the fourth region allows other color light except the second color light in the mixed color light to pass through, and the third region allows other color light except the third color light in the mixed color light to pass through.

9. The method for manufacturing an image sensor according to claim 8, wherein: The physical thicknesses of the second light-transmitting material layer in the first region and the third region are λ1 / (4*n1) and λ3 / (4*n1) respectively, and the physical thickness of the second region or the fourth region is λ2 / (4*n1); λ1, λ2 and λ3 are the wavelengths of the first color light, the second color light and the third color light respectively, and n1 is the refractive index of the second light-transmitting material layer.

10. The method for manufacturing an image sensor according to claim 8, wherein: The filter layer includes the first light-transmitting material layer and the second light-transmitting material layer which are periodically and alternately stacked. The first light-transmitting material layer in each period is closer to the substrate than the second light-transmitting material layer. The number of the periodic alternating stacking periods is greater than or equal to 3.

11. The method for manufacturing an image sensor according to claim 8, wherein: The material of the first light-transmitting material layer includes silicon oxide, and the material of the second light-transmitting material layer includes silicon nitride.

12. The method for manufacturing an image sensor according to claim 8, wherein: The method for manufacturing the image sensor further includes: A metal grid is formed on the substrate, and the metal grid is used to isolate the first region, the second region, the third region, and the fourth region from each other.

13. The method for manufacturing an image sensor according to claim 8, wherein: Before forming the filter layer on the substrate, the method for manufacturing the image sensor further includes: A pixel array is formed, and the array is arranged in the substrate. Pixels in the pixel array are correspondingly formed below the first area, the second area, the third area, and the fourth area, and adjacent pixels are isolated by an isolation structure.

14. The image sensor according to claim 13, wherein: The first area allows other color lights except the first color light in the mixed color light to pass through so that the pixels below the first area can calculate and output the complementary color of the first color light through an algorithm; The second area or the fourth area allows other color lights except the second color light in the mixed color light to pass through so that the pixels under the second area and the fourth area can calculate and output the complementary color of the second color light through an algorithm; The third area allows other color lights except the third color light in the mixed color light to pass through so that the pixels below the third area can output the complementary color of the third color light through algorithm calculation.

Images