CN115799282A - Image sensor with a plurality of pixels - Google Patents

Abstract

The invention provides an image sensor.A second color filter array of a single color is arranged at the periphery of a first color filter array of multiple colors, the single color is one of the multiple colors, and the thickness slowly-changing areas of other colors are removed or reduced, so that the utilization area of a substrate is increased and the cost waste is avoided. One or more grooves are formed in the light blocking structure, and the grooves are filled with the second color filter material to reduce the falling height of the top surface of the second color filter array, so that the monochromatic thickness gradual change area is reduced. A multicolored third color filter array is disposed between the first and second color filter arrays with the top surfaces of the second and third color filter arrays gradually decreasing in a direction toward the first color filter array, taking into account process tolerances and increasing process window.

Description

Image sensor with a plurality of pixels

Technical Field

The invention relates to the technical field of semiconductors, in particular to an image sensor.

Background

An image sensor is a core component of an image pickup apparatus, and a functional device capable of sensing radiation (e.g., optical radiation including, but not limited to, visible light, infrared rays, ultraviolet rays, etc.) and generating an electronic signal is widely used in various electronic products.

The image sensor includes a pixel region and a peripheral circuit region, which perform different functions, have different internal structures, and thus may have different heights. For example, the peripheral circuit region is a region for processing photocharges generated in the pixel region and generating electrical signals that can realize an optical image of a photographic subject. Incident light is irradiated not only on the pixel region but also on the peripheral circuit region where photocharges generated in the peripheral circuit region may form noise of an electrical signal, and the peripheral circuit region needs to be shielded with a light blocking structure to prevent the photocharges from generating noise in the peripheral circuit region, which forms a step therebetween to cause a height difference, or step height.

Due to the existence of the height difference, a certain gradient is generated on the surface of the color filter at the step, so that the uniformity of the color filter filled around the pixel area is poor, and a buffer area with a certain length needs to be additionally arranged, so that the area is difficult to be utilized, and the integration level of the image sensor is influenced.

Therefore, it is necessary to reduce the cost and adopt a simple manufacturing process to solve the above problems in the prior art.

Disclosure of Invention

The invention aims to provide an image sensor, which reduces an invalid region of the image sensor and improves the utilization area of a substrate through layout optimization.

In view of the above, the present invention provides an image sensor comprising: a first color filter array of multiple colors and a second color filter array of a single color at the periphery thereof, the single color being one of the multiple colors.

Preferably, the second color filters are arranged with a gap therebetween.

Preferably, the method further comprises the following steps: and a grid-shaped grating structure arranged between the adjacent first color filters.

Preferably, the grid structure is further disposed between adjacent second color filters.

Preferably, the single color is the color that is formed the latest among the multiple colors.

Preferably, the multiple colors include green, red and blue.

Preferably, the top surface of the first color filter array is not higher than the top surface of the second color filter array.

Preferably, the top surface of the second color filter array is gradually lowered in a direction toward the first color filter array.

Preferably, the method further comprises the following steps: and a multicolor third color filter array arranged between the first color filter array and the second color filter array, wherein the top surfaces of the second and third color filter arrays gradually descend.

Preferably, the method further comprises the following steps: and the light blocking structure is arranged at the periphery of the second color filter array and covered with the second color filter.

Preferably, one or more grooves are formed in the light blocking structure, and the second color filter further covers the grooves.

Preferably, the grooves are arranged in rows and/or columns.

Preferably, the groove is concentrically arranged with the light blocking structure.

Preferably, the groove penetrates or does not penetrate the light blocking structure.

Preferably, the light corresponding to the first and second color filters is selected from: infrared light, red light, green light, blue light, and ultraviolet light.

The invention is provided with a multicolor first color filter array in a pixel area, and a monochromatic second color filter array in a buffer area, wherein the monochromatic is one of the multicolor, and the ineffective area (such as the buffer area) in the layout of the image sensor is reduced by removing or reducing the thickness slowly-changing area of other colors, thereby improving the utilization area of the substrate and avoiding the cost waste.

Further, one or more grooves are formed in the light blocking structure, and the grooves are filled with the second color filter material to reduce the falling height of the top surface of the second color filter array, so that the monochromatic thickness-graded region is reduced.

Further, a third color filter array of multiple colors is disposed between the first and second color filter arrays in consideration of process errors and an increase in process window, and top surfaces of the second and third color filters are gradually lowered in a direction toward the first color filter array.

Drawings

Other features, objects and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments thereof, which is to be read in connection with the accompanying drawings.

FIG. 1 shows a schematic plan view of an image sensor of the prior art;

FIG. 2 showsbase:Sub>A schematic partial cross-sectional view along A-A' of FIG. 1;

fig. 3 is a schematic plan view of an image sensor according to a first embodiment of the present invention;

FIG. 4 shows a schematic partial cross-sectional view along B-B' of FIG. 3;

fig. 5 is a schematic plan view showing an image sensor according to a second embodiment of the present invention;

fig. 6 is a schematic partial cross-sectional view of an image sensor according to a second embodiment of the present invention;

fig. 7 is a schematic plan view of an image sensor according to a third embodiment of the present invention;

fig. 8 is a schematic partial cross-sectional view of an image sensor according to a third embodiment of the present invention;

fig. 9 is a schematic plan view of an image sensor according to a fourth embodiment of the present invention;

fig. 10 is a schematic partial cross-sectional view of an image sensor according to a fourth embodiment of the present invention;

fig. 11 is a schematic plan view of an image sensor according to a fifth embodiment of the present invention.

In the drawings, like or similar reference numbers indicate like or similar devices (modules) or steps throughout the different views.

Detailed Description

In order to make the contents of the present invention more clearly understood, the contents of the present invention will be further described with reference to the accompanying drawings. The invention is of course not limited to this particular embodiment, and general alternatives known to a person skilled in the art are also covered within the scope of the invention.

In the following detailed description of the embodiments of the present invention, in order to clearly illustrate the structure of the present invention and to facilitate explanation, it should be understood that the structure shown in the drawings is not drawn to general scale and is partially enlarged, modified or simplified, so that the present invention is not limited thereto.

FIG. 1 shows a schematic plan view of an image sensor of the prior art; fig. 2 showsbase:Sub>A schematic partial cross-sectional view alongbase:Sub>A-base:Sub>A' in fig. 1.

Referring to fig. 1 and 2, the image sensor may include a pixel region 101 and a peripheral circuit region 104, wherein the pixel region 101 has a plurality of pixel units (not shown) for sensing radiation, and the peripheral circuit region 104 has a structure (not shown) for performing other processes.

A color filter and a microlens (not shown) may be sequentially disposed over each of the pixel units, the pixel units being in an array form and may include: a red pixel for generating a photo-charge corresponding to incident light of a red spectral domain; a green pixel for generating a photo-charge corresponding to incident light of a green spectral domain; and a blue pixel for generating a photo-charge corresponding to incident light of a blue spectral domain. The color filters formed on the pixel units correspondingly form a multicolor color filter array, so that each pixel unit can be respectively used for sensing light radiation of different frequency bands.

As shown in fig. 2, the color filters include a green color filter 1131 for sensing green light, a red color filter 1132 for sensing red light, and a blue color filter 1133 for sensing blue light. The image sensor 100 further includes a grid-shaped metal grid 112 disposed between adjacent pixel cells to isolate adjacent ones of the color filters.

The green color filter 1131, the red color filter 1132, and the blue color filter 1133 are periodically arranged and are all disposed on the substrate 100 of the pixel region 101 and the buffer region 103, for example, two pixel units for sensing green light, one pixel unit for sensing red light, and one pixel unit for sensing blue light, so as to form a bayer arrangement.

The image sensor may also employ a color filter arrangement of the RGBW type, i.e. the image sensor comprises at least one group of pixel cells, each comprising four pixel cells arranged in a two by two array.

One of the pixel units is for sensing green light, and the green color filter 1131 is provided. One pixel unit for sensing red light is provided with the red color filter 1132. One pixel cell is provided with a blue color filter 1133 for sensing blue light, and one pixel cell is provided with a white color filter (not shown) for sensing white light, or no color filter is provided.

The microlens is an optical element, and may include a refractive microlens (not shown) based on the theory of refraction of light, a diffractive microlens (not shown) based on the theory of diffraction of light, and the like. In general, microlenses in image sensors need to be disposed on a flat surface to function well because of the processing involved with incident light. For example, the microlenses may be mounted directly over the individual color filters, in which case the upper surfaces of the color filters need to be sufficiently flat.

As shown in fig. 1, a light blocking structure 111 is disposed on the substrate 100 of the peripheral circuit region 104 around the pixel region 101, and forms a height difference with the substrate 100 of the pixel region 101. The following will be specifically described in conjunction with the light blocking structure. However, it should be understood by those skilled in the art that the reasons for the height difference between the peripheral circuit region and the pixel region may be various and not limited to the light blocking structure.

As shown in fig. 2, when the openings of the metal grids are filled to form color filters, a spin coating process is used to form a red color filter layer (not shown) or a green color filter layer (not shown) or a blue color filter layer (not shown) on the substrate 100, respectively, and the red color filter layer and/or the green color filter layer and/or the blue color filter layer further cover the light blocking structure 111 and fall down to the buffer area 103 along the top surface of the light blocking structure, so that the top surface of each color filter located in the buffer area 103 generates a slope.

In the direction toward the pixel region 101, the red color filter layer, the green color filter layer, or the blue color filter layer has a thickness gradually varying region in the buffer region, and the thicknesses of the red color filter layer, the green color filter layer, and the blue color filter layer gradually vary from high to low. Then, the red color filter layer or the green color filter layer or the blue color filter layer is patterned to form the green color filter 1131, the red color filter 1132 or the blue color filter 1133.

If the microlenses are formed on the color filters of the buffer area 103 having a slope, the microlenses also have a corresponding slope, which is disadvantageous for image display, and therefore, the buffer area 103 is not suitable for disposing pixel units and becomes an ineffective area. Therefore, the multicolor color filter array corresponding to the buffer region 103 cannot be used, which results in a waste of a part of the area of the substrate, and a waste of cost due to a limited area of the pixel region.

In order to solve the above problems in the prior art, the present invention provides an image sensor, in which a pixel region is provided with a first color filter array having multiple colors, and a buffer region is provided with a second color filter array having a single color, the single color being one of the multiple colors, and by removing or reducing a thickness-graded region of another color, an invalid region (e.g., buffer region) in a layout of the image sensor is reduced, thereby increasing a utilization area of a substrate and avoiding a waste of cost.

The light corresponding to the first color filter and the second color filter may be selected from: infrared light, red light, green light, blue light, and ultraviolet light.

Fig. 3 is a schematic plan view of an image sensor according to a first embodiment of the present invention; fig. 4 shows a schematic partial cross-sectional view along B-B' in fig. 3.

As shown in fig. 4, in the first embodiment, the first color filter 113 includes the green color filter 1131, the red color filter 1132 and the blue color filter 1133. The metal grid 112 is disposed between the adjacent first color filters 113. The color of the second color filter (i.e., the single color) is the latest formed one of the multiple colors, depending on the order of formation.

One skilled in the art will appreciate that an image sensor according to embodiments of the present disclosure may include any number of pixel cell groups, and each pixel cell group may include any number of one or more pixel cells arranged in any manner. The color, arrangement, number and size of the first color filter may be determined according to the resolution of the image sensor, and are not limited herein.

Referring to fig. 3 and 4, the top surfaces of the first color filters 113 in the pixel region 101 are flush with each other or have a height difference not exceeding a first predetermined value. A buffer area 103 and a peripheral circuit area 104 are sequentially arranged from near to far along the direction far away from the pixel area 101, the height difference between the second color filters positioned in the buffer area 103 does not exceed a second preset value, and the first preset value is smaller than the second preset value.

As shown in fig. 4, in the first embodiment, the single color is blue, and the remaining colors are red and green, that is, the second color filter is the blue color filter 1133.

Before forming the blue color filter 1133, when the red color filter layer and the green color filter layer are patterned to form the red color filter 1132 and the green color filter 1131, at least the red color filter layer and the green color filter layer in the buffer 103 are removed, so that a blank with a larger area exists on the buffer 103. When the blue filter layer is spin-coated, due to the fluidity of the material, the top surface of the blue filter layer may be rapidly lowered to a predetermined height when the blue filter layer is lowered from the light blocking structure 111 to the substrate 100.

The blue color filter 1133 is only disposed on the buffer 103, and the thickness gradient area of the single color is reduced by removing or reducing the thickness gradient area of the other color, that is, the lateral size of the buffer 103 is reduced, so as to increase the effective use area of the substrate 100.

Each of the color filter layers may be formed by any of the following coating techniques including, but not limited to, spin coating, brush coating, spray coating, electrostatic spray coating, 3D printing, and any combination of techniques thereof. It will be understood by those skilled in the art that the above-described process steps for forming each of the color filter layers are merely optional and not limiting, and each of the color filter layers of the present invention may be formed in any suitable process step.

In this embodiment, in consideration of process errors and an increase in process window, a dummy region 102 is further disposed between the pixel region 101 and the buffer region 103, the dummy region 102 is provided with a plurality of third color filters to form a multi-color third color filter array, and the third color filters may include the green color filter 1131, the red color filter 1132, and the blue color filter 1133.

The multicolor third color filter array is disposed between the first color filter array and the second color filter array, and the top surfaces of the second and third color filter arrays gradually descend in a direction toward the pixel region 101.

Fig. 5 is a schematic plan view of an image sensor according to a second embodiment of the present invention; fig. 6 is a schematic partial cross-sectional view of an image sensor according to a second embodiment of the present invention.

Referring to fig. 5 and fig. 6, the second color filters are disposed on the buffer region 103 and spaced apart from each other by a gap. That is, the buffer region 103 is not provided with the metal grid 112 for isolating the adjacent second color filters except the second color filters, so as to further increase the blank area between the peripheral circuit region 104 and the pixel region 101, so that the top surface of the second color filter (such as a blue color filter) can be more rapidly lowered to a predetermined height, thereby shortening the lateral dimension of the buffer region 103.

Fig. 7 is a schematic plan view of an image sensor according to a third embodiment of the present invention; fig. 8 is a schematic partial cross-sectional view of an image sensor according to a third embodiment of the present invention.

Referring to fig. 7 and 8, one or more grooves 114 are formed in the light blocking structure 111, and the second color filter also covers the grooves 114.

The recess 114 extends inward from the top surface of the light blocking structure 111, and the material of the second color filter layer has fluidity and fills the recess 114.

The top surface of the material of the second color filter on the light blocking structure 111 first falls from a first height and then rises to a second height in a direction toward the pixel region 101, after which the material of the second color filter falls from the light blocking structure 111 to the substrate 100. The second height is lower than the first height, thereby reducing a descending height of the top surface of the second color filter array to shorten a lateral dimension of the buffer region.

Fig. 9 is a schematic plan view of an image sensor according to a fourth embodiment of the present invention; fig. 10 is a schematic partial cross-sectional view of an image sensor according to a fourth embodiment of the present invention; fig. 11 is a schematic plan view of an image sensor according to a fifth embodiment of the present invention.

The grooves 114 may be arranged in rows and/or columns within the light barrier structure 111.

Referring to fig. 9 and 10, the groove 114 may be disposed concentrically with the light blocking structure 111 to surround the pixel region in a ring shape.

In the fourth embodiment, as shown in fig. 10, the recess 114 may or may not penetrate the light blocking structure 111 on the basis that the metal grid 112 is not disposed on the buffer 103, and the falling height of the top surface of the second color filter array is adjusted by setting the depth of the recess 114, so as to flexibly adjust the lateral dimension of the buffer 103.

In the fifth embodiment, as shown in fig. 11, the grooves 114 may penetrate through the light blocking structure 111, and a plurality of the grooves 114 are disposed in rows and/or columns in the light blocking structure 111 to reduce the thickness gradient area of the monochromatic second color filter. In addition, the shape, location and size of the recess 114 can be flexibly configured.

The invention sets a first multicolor color filter array in the pixel area, sets a second monochromatic color filter array in the buffer area, the monochromatic color is one of the multicolor, and removes or reduces the thickness slowly-changing area of other colors, thereby reducing the invalid area (such as buffer area) in the picture of the image sensor, improving the utilization area of the substrate and avoiding the cost waste.

Further, one or more grooves are formed in the light blocking structure, and the grooves are filled with the second color filter material to reduce the falling height of the top surface of the second color filter array, so that the monochromatic thickness graded region is reduced.

Further, a third color filter array of multiple colors is disposed between the first and second color filter arrays in consideration of process errors and an increase in process window, and top surfaces of the second and third color filters are gradually lowered in a direction toward the first color filter array.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. It will furthermore be evident that the word "comprising" does not exclude other elements or steps, and the word "a" or "an" does not exclude a plurality. Several elements recited in the apparatus claims may also be implemented by one element. The terms first, second, etc. are used to denote names, but not to denote any particular order.

Claims (15)

1. An image sensor, comprising: a first color filter array of multiple colors and a second color filter array of a single color at the periphery thereof, the single color being one of the multiple colors.

2. The image sensor as in claim 1, wherein the second color filters are disposed with a gap therebetween.

3. The image sensor of claim 1, further comprising: and a grid-shaped grating structure arranged between the adjacent first color filters.

4. The image sensor of claim 3, wherein the grid structure is further disposed between adjacent ones of the second color filters.

5. The image sensor of claim 1, wherein the single color is a color of the multi-color that is formed latest.

6. The image sensor of claim 5, wherein the multiple colors include green, red, and blue.

7. The image sensor of claim 1, wherein a top surface of the first color filter array is no higher than a top surface of the second color filter array.

8. The image sensor of claim 7, wherein the top surface of the second color filter array is tapered in a direction toward the first color filter array.

9. The image sensor of claim 8, further comprising: and a third multicolor color filter array arranged between the first color filter array and the second color filter array, wherein the top surfaces of the second and third color filter arrays gradually descend.

10. The image sensor of any of claims 1 to 9, further comprising: and the light blocking structure is arranged at the periphery of the second color filter array and covered with the second color filter.

11. The image sensor as in claim 10, wherein one or more recesses are formed in the light blocking structure, the second color filter further covering the recesses.

12. The image sensor of claim 11, wherein the grooves are arranged in rows and/or columns.

13. The image sensor of claim 11, wherein the recess is disposed concentrically with the light blocking structure.

14. The image sensor of claim 11, wherein the recess penetrates or does not penetrate the light blocking structure.

15. The image sensor of claim 1, wherein the light corresponding to the first and second color filters is selected from the group consisting of: infrared light, red light, green light, blue light, and ultraviolet light.

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