CN115497965A - Image sensor, manufacturing method thereof, and method for detecting crosstalk and halo between adjacent pixels of image sensor - Google Patents

Abstract

The invention provides an image sensor and its preparation method, and a method for detecting crosstalk and halo between adjacent pixels of the image sensor. The image sensor includes: a pixel array composed of pixel units, and the pixel array includes a photosensitive The pixel area and the black pixel area used for calibration; on the surface of the photosensitive pixel area and/or the black pixel area, a discontinuous light-shielding layer is covered to block the light from entering, wherein the pixel unit covered by the light-shielding layer is a light-shielding pixel unit, and the pixel unit not covered by the light-shielding layer is a non-light-shielding pixel unit. By designing the light-shielding layer of the black pixel area to be discontinuous, stress and process damage can be relieved, the performance difference between the black pixel area and the photosensitive pixel area can be reduced, and better black level calibration can be achieved; through the design of the discontinuous light-shielding layer , which can realize the halo and crosstalk test between monochrome pixels and pixels with unfinished pigment process.

Description

Image sensor and manufacturing method thereof, and serial connection between adjacent pixels of the image sensor Interference and halo detection method

technical field

The present invention relates to the technical field of image sensors, in particular to an image sensor and a preparation method thereof, and a method for detecting crosstalk and halo between adjacent pixels of the image sensor.

Background technique

In the image sensor, there is a photosensitive pixel array and a black pixel array, the surface of the black pixel array is covered with a light-shielding layer, and the black pixel array is used to calibrate the photosensitive pixel signal of the photosensitive pixel array by counting the black level value. However, the black pixel array has more light-shielding layers than the photosensitive pixel array, which will introduce differences such as stress and process damage, resulting in a deviation between the black level of the black pixel array and the black level of the photosensitive pixel array, resulting in ineffective black level calibration. Eliminate black level noise, which affects the image signal-to-noise ratio.

Inter-pixel crosstalk (Cross Talk) and halo (Blooming) of image sensors are important technical indicators of pixel design, which have a significant impact on imaging performance.

For an image sensor with a color filter, the method for testing crosstalk or halo is: illuminate the pixel, and calculate the crosstalk and halo data by detecting the brightness values of the target pixel and adjacent pixels.

As shown in Figure 1, the existing color filters are arranged in an RGGB manner, wherein R represents a pixel unit covered with a red filter, B represents a pixel unit covered with a blue filter film, and G1 (2 ) represents a pixel unit covered with a green filter film. In the prior art, for crosstalk and halo tests between pixels of image sensors with color filters, green light is usually used to irradiate the pixel area, and the brightness in the pixel units G1, G2, B, and R are respectively collected. value, forming the brightness-exposure time relationship graph shown in Figure 2, wherein k _G1 is the brightness slope of the pixel unit G1, k _G2 is the brightness slope of the pixel unit G2, and k _R a and k _R b are the brightness of the pixel unit R. Brightness slope, k _B a, k _B b is the brightness slope of pixel unit B.

The crosstalk value of pixel unit G1 and G2 to pixel unit R is k _R a*2/(k _G1 + k _G2 ); the halo value of pixel unit G1 and G2 to pixel unit R is k _R b*2/(k _G1 + k _G2 ) - k _R a*2/(k _G1 + k _G2 ).

For monochrome image sensors or image sensors without pigment processing, crosstalk data cannot be obtained through different colors, and the influence of crosstalk and blooming on the final image cannot be evaluated in a timely and accurate manner. Increase the cost and cycle of pixel optimization.

Contents of the invention

The purpose of the present invention is to provide an image sensor and its preparation method, as well as a method for detecting crosstalk and halo between adjacent pixels of the image sensor, which are used to alleviate stress, process damage, etc., to achieve better black level calibration, and Ability to test crosstalk or halo values between adjacent pixels of an image sensor.

Based on the above considerations, the present invention provides an image sensor, including a pixel array composed of pixel units, the pixel array includes a photosensitive pixel area for light sensing and a black pixel area for calibration;

The surface of the photosensitive pixel area and/or the black pixel area is covered with a discontinuous light-shielding layer to block light from entering, wherein the pixel unit covered by the light-shielding layer is a light-shielding pixel unit, and the pixel unit not covered by the light-shielding layer The covered pixel units are non-shading pixel units.

Optionally, other pixel units adjacent to a certain non-shading pixel unit are all light-shielding pixel units.

Optionally, determine the light-shielding pixel units that are connected to certain two vertices, and the other two pixel units that share the vertices are non-light-shielding pixel units.

Optionally, on the surface of the black pixel region, the covered light-shielding layer is discontinuous, so as to alleviate the stress and process damage of the light-shielding layer on the pixel units in the black pixel region.

Optionally, the light-shielding layer is metal or organic light-shielding material.

The present invention also provides a method for preparing an image sensor, comprising the steps of:

providing a pixel array composed of pixel units, the pixel array including a light-sensing pixel area for light-sensing and a black pixel area for calibration;

A discontinuous light-shielding layer is formed on the surface of the photosensitive pixel area and/or the black pixel area to block light from entering.

Optionally, the method for forming a discontinuous light-shielding layer on the surface of the photosensitive pixel area and/or the black pixel area includes: depositing a light-shielding layer on the surface of the pixel array;

Part of the light-shielding layer is removed by photolithography and etching, and a discontinuous light-shielding layer is formed on the surface of the photosensitive pixel area and/or the black pixel area.

Optionally, in the pixel array, the light-shielding layer on the surface of a certain pixel unit is removed, and the light-shielding layer on the surface of other pixel units adjacent to the pixel unit remains.

Optionally, in the pixel array, the light-shielding layer on the surface of the pixel unit where two vertices are connected is removed, and the light-shielding layer on the surface of the other two pixel units sharing the vertex is retained.

The present invention also provides a method for detecting crosstalk and halo between adjacent pixels of an image sensor. The image sensor includes a pixel array composed of a plurality of pixel units; a discontinuous light-shielding layer is formed on the surface of the pixel array to prevent light In, the pixel unit covered by the light-shielding layer is a light-shielding pixel unit, and the pixel unit not covered by the light-shielding layer is a non-light-shielding pixel unit;

The pixel array is irradiated with light, and the luminance values of the shading pixel unit and the non-shading pixel unit adjacent to the shading pixel unit are respectively measured and calculated to obtain crosstalk or halo data between the pixel units.

Optionally, a certain pixel unit in the pixel array is selected as a non-shading pixel unit, and all other pixel units adjacent to the non-shielding pixel unit are set as light-shielding pixel units.

Optionally, in the pixel array, a pixel unit with two connected vertices is selected as a non-shading pixel unit, and the other two pixel units sharing the vertex are set as a light-shielding pixel unit.

Optionally, it is applied to the crosstalk or halo test between pixel units when the pigment process stage is not performed in the color image sensor manufacturing process.

Optionally, it is applied to the crosstalk or halo test between the pixel units of the monochrome image sensor.

The image sensor and its preparation method provided by the present invention, as well as the crosstalk and halo detection method between adjacent pixels of the image sensor, have the following beneficial effects:

By designing the light-shielding layer in the black pixel area to be discontinuous, it can relieve stress, process damage, etc., reduce the performance difference between the black pixel area and the photosensitive pixel area, and achieve better black level calibration;

Through the design of the discontinuous shading layer, the halo and crosstalk test between monochrome pixels and pixels with unfinished pigment process can be realized;

The discontinuous light-shielding layer design can be placed in the black pixel area. On the basis of using the existing light-shielding layer, the halo and crosstalk test between pixels can be realized without increasing the design cost and design area; In some special stages (such as the front-illumination process stage test of the back-illuminated chip), the light-shielding layer can also be added to realize the design of the discontinuous light-shielding layer, so as to perform the halo test between pixels.

Description of drawings

Other features, objects and advantages of the present invention will become more apparent by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of an existing color pixel array;

Fig. 2 shows the relationship diagram of the brightness-exposure time of the existing color pixel array;

Fig. 3 shows the schematic diagram of the pixel array provided for the present invention;

FIG. 4 shows a schematic diagram of a pixel array according to another embodiment of the present invention;

FIG. 5 is a graph showing the relationship between brightness and exposure time of the pixel array provided by the present invention.

In the drawings, the same or similar reference numerals denote the same or similar means (modules) or steps throughout different views.

detailed description

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, the present invention can be implemented in many other ways different from those described here, and those skilled in the art can make similar extensions without violating the connotation of the present invention, so the present invention is not limited by the specific implementations disclosed below.

Secondly, the present invention is described in detail by means of schematic diagrams. When describing the embodiments of the present invention in detail, for convenience of explanation, the schematic diagrams are only examples, which should not limit the protection scope of the present invention.

The technical solutions of the present invention will be described in detail below through specific embodiments in conjunction with the accompanying drawings.

The invention provides an image sensor and a preparation method thereof. A discontinuous light-shielding layer is covered on the light-sensitive pixel array or the black pixel array, or on the light-sensitive pixel array and the black pixel array. Forming a discontinuous light-shielding layer can reduce the stress of the light-shielding layer on the pixel array.

The technical solution provided by this embodiment will be described in detail below in conjunction with the accompanying drawings.

As shown in FIG. 3 , this embodiment provides an image sensor, including a pixel array composed of pixel units, taking an 8*8 pixel array 10 as an example. The pixel array 10 includes row 101, row 102, row 103, row 104, row 105, row 106, row 107, row 108 from top to bottom and column a, column b and column c from left to right , column d, column e, column f, column g, column h. The pixel array 10 includes a light-sensing pixel area 11 for light-sensing and a black pixel area 12 around the light-sensing pixel area 11 for calibration. The black pixel area can be placed anywhere around the photosensitive pixel area.

The surface of the photosensitive pixel area 11 or the black pixel area 12 or the surface of the photosensitive pixel area 11 and the black pixel area 12 is covered with a discontinuous light-shielding layer, which is used to block light from entering. The pixel unit covered by the light-shielding layer is a light-shielding pixel unit, and the pixel unit not covered by the light-shielding layer is a non-light-shielding pixel unit.

In this embodiment, the surface of the black pixel region 12 has a discontinuous light-shielding layer 131, wherein the pixel units 101e, 102a, 102b, 102d, and 102g are non-shielding pixel units. By designing the light-shielding layer 131 of the black pixel region 12 to be discontinuous, on the basis of the existing light-shielding layer, interrupting the light-shielding layer can alleviate the stress and process damage to the black pixel region caused by the light-shielding layer. , to reduce the performance difference between the black pixel area and the light-sensitive pixel area, and achieve better black level calibration.

In addition, the pixel units around the non-shading pixel unit 102g are all covered by the light-shielding layer 131. This structure can not only relieve the stress caused by the light-shielding layer, but also be used for crosstalk and halo tests between pixels. Alternatively, the pixel units 101e and 102d are non-shading pixel units, and the pixel units 101d and 102e that share vertices with the pixel units 101e and 102d are light-shielding pixel units. This structure can also be used for crosstalk or halo testing. Specifically, by irradiating the pixel array with light, the luminance values of the shading pixel unit and the non-shading pixel unit adjacent to the shading pixel unit are respectively measured and calculated to obtain crosstalk or halo data between pixel units. On the basis of using the existing light-shielding layer and selecting non-shading pixel units, it is possible to perform crosstalk or halo tests without increasing the design cost and design area.

In this embodiment, in the photosensitive pixel area 11, there is a discontinuous light-shielding layer 132, wherein the pixel units 104d and 105c are light-shielding pixel units, and the pixel units 104c and 105d sharing vertices with the pixel units 104d and 105c are non-light-shielding Pixel unit, this structure can be used for crosstalk or halo test. Alternatively, the surrounding pixel units of the non-shading pixel unit 107g are all covered by the light-shielding layer 132, and this structure can also be used for crosstalk or halo testing. Specifically, by irradiating the pixel array with light, the luminance values of the shading pixel unit and the non-shading pixel unit adjacent to the shading pixel unit are respectively measured and calculated to obtain crosstalk or halo data between pixel units.

The arrangement of the discontinuous light-shielding layer also has other forms, not limited to the form shown in FIG. 3 , and the specific form is not limited.

It should be noted that the light-shielding layer may cover multiple complete pixel units or parts of pixel units. In other embodiments, as shown in FIG. 4 , the light shielding layers 131', 132' cover part of the pixel units 101e', 101f', 102f', 103f', 105e', 106d'.

The material of the light-shielding layer is metal or organic light-shielding material.

The present invention also provides a method for preparing an image sensor, comprising the steps of: providing a pixel array composed of pixel units, the pixel array including a photosensitive pixel area for light sensing and a black pixel area for calibration;

A discontinuous light-shielding layer is formed on the surface of the photosensitive pixel area and/or the black pixel area to block light from entering.

Specifically, referring to FIG. 3 , the method for forming a discontinuous light-shielding layer includes: depositing a light-shielding layer on the surface of the pixel array;

Part of the light-shielding layer is removed by photolithography and etching, and a discontinuous light-shielding layer is formed on the surface of the photosensitive pixel area 11 or the surface of the black pixel area 12 or the surfaces of the photosensitive pixel area 11 and the black pixel area 12 .

As an example, in the pixel array, the discontinuous light-shielding layer 13 is obtained by removing the light-shielding layer on the surface of the pixel unit 102g or 107g and retaining the light-shielding layer on the surface of other pixel units adjacent to the pixel unit 102g or 107g.

As an example, in the pixel array, the discontinuous light-shielding layer 13 is obtained by removing the light-shielding layer on the surface of two pixel units 104c and 105d that are connected at the same vertex, and retaining the light-shielding layer on the surface of the other two pixel units 104d and 105c that share the vertex. .

The setting of the discontinuous light-shielding layer also has other forms, which are not limited here.

The present invention also provides a method for detecting crosstalk and halo between adjacent pixels of an image sensor, the main steps of which are as follows:

The image sensor includes a pixel array composed of a plurality of pixel units;

On the surface of the pixel array, a discontinuous light-shielding layer is formed to prevent light from entering, the pixel units covered by the light-shielding layer are light-shielding pixel units, and the pixel units not covered by the light-shielding layer are non-light-shielding pixel units;

The pixel array is irradiated with light, and the luminance values of the shading pixel unit and the non-shading pixel unit adjacent to the shading pixel unit are respectively measured and calculated to obtain crosstalk or halo data between the pixel units.

For the halo or crosstalk test between the pixel units of the achromatic filter, by setting a discontinuous light-shielding layer, the light-shielding pixel unit and the non-light-shielding pixel unit are obtained, and the light-shielding pixel unit and the light-shielding pixel unit obtained by the test are compared with the light-shielding pixel unit The brightness of adjacent non-shading pixel units is analyzed and processed to obtain crosstalk or halo values. The method can be applied to the crosstalk or halo test between pixel units when the pigment process stage is not performed in the manufacturing process of the monochrome image sensor or the color image sensor.

In order to obtain more accurate pixel crosstalk or halo data, a certain pixel unit is determined from the pixel area, and all other pixel units adjacent to the pixel unit are designed as light-shielding pixel units, so as to accurately obtain the pixel unit’s surrounding neighbors. The crosstalk or halo value of the pixel unit.

As an example, as shown in FIG. 3 , an 8*8 pixel array 10 is taken as an example. Select the pixel unit 102g or 107g, and design all the pixel units surrounding the pixel unit 102g or 107g as light-shielding pixel units. The pixel area is illuminated to obtain the brightness value of the pixel unit 102g or 107g and its surrounding black pixel units, and is calculated to obtain the crosstalk or halo value of the pixel unit 102g or 107g to any surrounding pixel unit.

Specifically, the detection of the crosstalk or halo value of the pixel unit 107g to its adjacent 106h is taken as an example. The pixel area is irradiated with light, and the luminance values in the pixel units _107g and _106h are respectively collected to form a luminance-exposure time relationship diagram as shown in FIG. k _h b is the brightness slope of the pixel unit 106h.

The crosstalk value of the pixel unit 107g to the pixel unit 106h is k _h a/k _g ; the halo value of the pixel unit 107g to the pixel unit 106h is k _h b/ _kg − k _h a/k _g .

Similarly, this method can also be used to measure the halo or crosstalk value of the pixel unit 102g to its surrounding pixel units.

For color image sensors, the filters are usually arranged in the form of RGGB. In order to find the problem of crosstalk or halo between pixels earlier, it can be used when the pigment process is not performed or the color filter stage is not formed. Crosstalk or halo between pixel units is tested.

Specifically, as shown in FIG. 3 , in the pixel region, two pixel units 101e and 102d connected to each other are determined, and the other two pixel units 101b and 102e sharing the vertices are used as light-shielding pixel units to irradiate the pixel region with light. , the luminance values of the light-shielding pixel units 101d, 102e and the non-shading pixel units 101e, 102d are respectively measured and calculated, so as to obtain the crosstalk or halo value of the pixel units 101e, 102d to adjacent pixel units. The specific calculation process is as follows In the prior art, the crosstalk and halo of the pixel unit G1 and G2 to the pixel unit R are calculated in the same way.

Similarly, the crosstalk or halo values of the pixel units 104c and 105d to adjacent pixel units can also be obtained by the same method.

The setting of light-shielding pixel units and non-light-shielding pixel units is not limited to the two forms shown in FIG. 3 , and other forms of setting can also be performed as required, which is not limited here.

It should be noted that, for pixel arrays with light-sensitive pixel areas and black pixel areas, it is possible to give priority to setting the discontinuous light-shielding layer for testing crosstalk or halo in the black pixel area, so that the existing light-shielding layer can be used, and when it is not possible In the case of increasing the design cost and design area, the test of halo or crosstalk can be completed.

For some special stages (such as the front-illumination process stage test of the back-illuminated chip), the design of the discontinuous light-shielding layer can also be realized by adding a light-shielding layer, so as to test the crosstalk or halo between pixels.

To sum up, the present invention provides an image sensor and its preparation method, as well as a method for detecting crosstalk and halo between adjacent pixels of the image sensor. By designing the light-shielding layer in the black pixel area to be discontinuous, the stress can be relieved. , process damage, etc., reduce the performance difference between the black pixel area and the photosensitive pixel area, and achieve better black level calibration; through the design of the discontinuous light-shielding layer, the halo between monochrome pixels and pixels that have not completed the pigment process can be realized , Crosstalk test; the discontinuous light-shielding layer design can be placed in the black pixel area, and the existing light-shielding layer can be used to achieve halo and crosstalk between pixels without increasing design cost and design area Test; for some special stages (such as the front-illumination process stage test of the back-illuminated chip), the light-shielding layer can also be added to realize the design of the discontinuous light-shielding layer, so as to perform the halo test between pixels.

It will be apparent to those skilled in the art that the invention is not limited to the details of the above-described exemplary embodiments, but that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Accordingly, the embodiments should be regarded in all respects as exemplary and not restrictive. Furthermore, it is obvious that the word "comprising" does not exclude other elements and steps, and the word "a" does not exclude the plural. A plurality of elements recited in device claims may also be embodied by one element. The words first, second, etc. are used to denote names and do not imply any particular order.

Claims (14)

1. An image sensor, characterized in that it includes a pixel array composed of pixel units, the pixel array includes a photosensitive pixel area for light sensing and a black pixel area for calibration; The surface of the photosensitive pixel area and/or the black pixel area is covered with a discontinuous light-shielding layer to block light from entering, wherein the pixel unit covered by the light-shielding layer is a light-shielding pixel unit, and the pixel unit not covered by the light-shielding layer The covered pixel units are non-shading pixel units. 2 . The image sensor according to claim 1 , wherein all other pixel units adjacent to a certain non-shading pixel unit are light-shielding pixel units. 3 . The image sensor according to claim 1 , wherein the light-shielding pixel units connected to certain two vertices are determined, and the other two pixel units sharing the vertices are non-shading pixel units. 4 . 4. The image sensor according to claim 1, characterized in that, on the surface of the black pixel area, the covered light-shielding layer is discontinuous, so as to alleviate the stress and process damage of the light-shielding layer on the pixel units in the black pixel area . 5. The image sensor according to claim 1, wherein the light-shielding layer is a metal or an organic light-shielding material. 6. A method for preparing an image sensor, comprising the steps of: providing a pixel array composed of pixel units, the pixel array including a light-sensing pixel area for light-sensing and a black pixel area for calibration; A discontinuous light-shielding layer is formed on the surface of the photosensitive pixel area and/or the black pixel area to block light from entering. 7. The method for preparing an image sensor according to claim 6, wherein the method of forming a discontinuous light-shielding layer on the surface of the photosensitive pixel area and/or the black pixel area comprises: depositing a light-shielding layer on the surface of the pixel array Floor; Part of the light-shielding layer is removed by photolithography and etching, and a discontinuous light-shielding layer is formed on the surface of the photosensitive pixel area and/or the black pixel area. 8 . The method for manufacturing an image sensor according to claim 7 , wherein in the pixel array, the light-shielding layer on the surface of a certain pixel unit is removed, and the light-shielding layer on the surface of other pixel units adjacent to the pixel unit is retained. 9. The method for preparing an image sensor according to claim 7, wherein, in the pixel array, the light-shielding layer on the surface of the pixel unit connected by two vertices is removed, and the light-shielding layer on the surface of the other two pixel units sharing the vertex is reserved. Shading layer. 10. A detection method for crosstalk and halo between adjacent pixels of an image sensor, characterized in that the image sensor includes a pixel array composed of a plurality of pixel units; on the surface of the pixel array, a discontinuous light-shielding layer is formed to prevent When light is incident, the pixel unit covered by the light-shielding layer is a light-shielding pixel unit, and the pixel unit not covered by the light-shielding layer is a non-light-shielding pixel unit; The pixel array is irradiated with light, and the luminance values of the shading pixel unit and the non-shading pixel unit adjacent to the shading pixel unit are respectively measured and calculated to obtain crosstalk or halo data between the pixel units. 11. The method for detecting crosstalk and halo between adjacent pixels according to claim 10, wherein a certain pixel unit is selected as a non-shielding pixel unit in the pixel array, and the pixel unit adjacent to the non-shielding pixel unit All the other pixel units are set as light-shielding pixel units. 12. The detection method of crosstalk and halo between adjacent pixels according to claim 10, characterized in that, in the pixel array, select the pixel unit connected by two vertices as the non-shielding pixel unit, and share the vertices The other two pixel units are set as light-shielding pixel units. 13. The method for detecting crosstalk and halo between adjacent pixels of a monochrome image sensor according to claim 10, characterized in that it is applied to the crosstalk between pixel units or Halo test. 14. The method for detecting crosstalk and halo between adjacent pixels of a monochrome image sensor according to claim 10, characterized in that it is applied to the crosstalk or halo test between pixel units of a monochrome image sensor.

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