Image sensor forming method and image sensor

Abstract

The invention provides a method for forming an image sensor, which comprises the following steps of: forming a light blocking structure comprising a plurality of layers and sections of short-line groove through holes around a pixel array of the image sensor so as to reduce the influence of stress. The light blocking effect is achieved without adopting a whole row of silicon through hole structures, meanwhile, due to the design of multiple small sections, huge stress cannot be introduced, and the problems of light emitting and overlarge stress can be solved at the same time. According to the scheme, structural design does not need to be repeatedly carried out for different products to find a scheme with small stress.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to an image sensor forming method and an image sensor. Background Art

[0002] CMOS image sensors are currently widely used in the field of image acquisition. The pixel array of an image sensor is mainly composed of two parts: a readout row and a blackout row. The readout row is used to sense light and provide imaging signals, while the blackout row is used to read the optical black level. The optical black level is the signal caused by the internal current generated by the pixel unit when there is no light. Ideally, the optical black level values ​​of the blackout area and the photosensitive area should be the same.

[0003] Considering that the human eye is more sensitive to the details in the dark part of the image, and to facilitate signal noise reduction processing, image sensor manufacturers generally add a fixed base value before signal processing, so that the readout signal is between 16 and 255. When performing a black mask test on an image sensor, ideally, the signal difference between the readout line and the black mask line should be equal to this base value; however, due to differences in the process and structure of the readout line and the black mask line, the dark current level is different, and the measurement result of the base value often deviates from the set value.

[0004] When the device emits more and more light and obviously affects the pixel performance, a through silicon via isolation structure is usually added to the back-illuminated image sensor process to block the light to eliminate the effect of the emission. However, the use of through silicon vias to block light will also bring new negative effects and generate greater stress. Although the stress can be reduced by reducing the length of the through silicon vias and arranging multiple groups side by side, the light blocking effect cannot be taken into account. Summary of the invention

[0005] The object of the present invention is to provide a method for forming an image sensor, comprising: A light shielding structure including multiple layers and multiple sections of short-line trench through holes is formed around the pixel array of the image sensor to reduce the influence of stress.

[0006] Furthermore, at least two layers of the short-line groove through holes are arranged on one side of the long-line groove through holes.

[0007] Furthermore, the multi-layer and multi-segment short-line groove through holes are C-shaped structures and are arranged in an inlaid manner to improve the light-blocking effect of the light-blocking structure.

[0008] Furthermore, the multiple layers and multiple sections of short-line groove through holes are inlaid with each other to form a zigzag arrangement, so as to improve the light-blocking effect of the light-blocking structure.

[0009] Furthermore, at least two layers of the short-line groove through holes are arranged on one side of the long-line groove through holes.

[0010] Furthermore, the short-line groove through holes in each layer are arranged in a staggered manner to improve the light-blocking effect of the light-blocking structure.

[0011] Furthermore, the line width of the short-line trench via is 0.4-0.8 microns.

[0012] Further, forming the light blocking structure includes: Etching the semiconductor substrate according to a preset photolithography pattern to form a trench through hole; Metal material is filled in the groove through hole to form the light blocking structure.

[0013] Furthermore, the metal material includes tungsten.

[0014] An image sensor is formed by using the above-mentioned image sensor forming method.

[0015] The present invention proposes a new method for forming an image sensor through the above scheme. The present invention does not need to use a whole row of through silicon via structures to solve the light blocking effect. At the same time, because the design of multiple small segments will not introduce huge stress, it can solve the problems of luminescence and excessive stress at the same time. The scheme of the present invention does not need to repeat the structural design for different products to find a solution with less stress. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Other features, objects and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings. Figure 1~Figure 5 Schematic diagrams of the shapes and arrangements of light-blocking structures in different embodiments of the present invention. In the drawings, the same or similar reference numerals denote the same or similar devices (modules) or steps throughout different drawings. Implementation

[0017] The object of the present invention is to provide a method for forming an image sensor, comprising: A light shielding structure including multiple layers and multiple segments of short-line trench through holes 100 is formed around the pixel array of the image sensor to reduce the influence of stress.

[0018] Preferably, the line width of the short-line trench through hole 100 is 0.4-0.8 micrometers to achieve a better light-shielding effect.

[0019] like Figure 1~Figure 5 The figure shows the shape and arrangement examples of the short-line trench vias 100 in various embodiments of the present invention.

[0020] Preferably, in embodiment 1, Figure 1 As shown, the short-line groove through holes 100 of each layer are arranged in a staggered manner to improve the light-shielding effect of the light-shielding structure. The staggered arrangement can prevent light from entering through the gaps of the short-line groove through holes 100, thereby improving the light-shielding effect.

[0021] In another optional embodiment 2, the multi-layer short-line trench vias 100 may be arranged on both sides of a long-line trench via 200, such as Figure 2 The short-line groove through hole 100 can effectively reduce stress, and the long-line groove through hole 200 can also completely block light.

[0022] Preferably, on this basis, Figure 3 As shown, in order to further enhance the light shielding effect, at least two layers of the short-line groove through holes 100 can be arranged on one side of the long-line groove through hole 200 to avoid the problem of light diffraction in the multiple layers of short-line groove through holes 100.

[0023] Further, in Example 3, Figure 4 As shown, the multi-layer and multi-segment short-line groove through holes 100 can be a C-shaped structure and are arranged in an inlaid manner to improve the light-blocking effect of the light-blocking structure. This shape and arrangement can further avoid light diffraction, achieve a better light-blocking effect, and will not increase stress.

[0024] Preferably, if Figure 5 As shown, the multi-layer and multi-segment short-line groove through holes 100 are inlaid with each other to form a zigzag arrangement, further improving the light-blocking effect of the light-blocking structure.

[0025] In the present invention, preferably, the light blocking structure can be formed by the following steps: Step S100: etching the semiconductor substrate according to a preset photolithography pattern to form a trench through hole; Step S200: filling the trench through hole with metal material to form the light blocking structure.

[0026] The trench through hole includes both the short-line trench through hole 100 in the above-mentioned embodiment and the long-line trench through hole. In an optional embodiment, metal tungsten can be filled in the through hole to achieve a light-blocking effect.

[0027] The present invention also provides an image sensor, which is formed by using the above-mentioned image sensor forming method.

[0028] The present invention proposes a new method for forming an image sensor through the above scheme. The present invention does not need to use a whole row of through silicon via structures to solve the light blocking effect. At the same time, because the design of multiple small segments will not introduce huge stress, it can solve the problems of luminescence and excessive stress at the same time. The scheme of the present invention does not need to repeat the structural design for different products to find a solution with less stress.

[0029] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, in any case, the embodiments should be considered exemplary and non-restrictive. In addition, it is clear that the term "comprising" does not exclude other elements and steps, and the wording "a" does not exclude the plural. Multiple elements stated in a device claim may also be implemented by one element. The terms first, second, etc. are used to indicate names and do not indicate any particular order.

Claims

1. A method for forming an image sensor, characterized in that: include: A light shielding structure including multiple layers and multiple sections of short-line trench through holes is formed around the pixel array of the image sensor to reduce the influence of stress.

2. The method for forming an image sensor according to claim 1, wherein: The multi-layer and multi-segment short-line groove through holes are in a C-shaped structure and are arranged in an inlaid manner to improve the light-blocking effect of the light-blocking structure.

3. The method for forming an image sensor according to claim 2, wherein: The multiple layers and multiple sections of short-line groove through holes are inlaid with each other to form a zigzag arrangement, so as to improve the light-blocking effect of the light-blocking structure.

4. The method for forming an image sensor according to claim 1, wherein: The multi-layer short-line trench through holes are respectively arranged on both sides of a long-line trench through hole.

5. The method for forming an image sensor according to claim 4, wherein: At least two layers of the short-line groove through holes are arranged on one side of the long-line groove through holes.

6. The method for forming an image sensor according to claim 1, wherein: The short-line groove through holes in each layer are arranged in a staggered manner to improve the light-blocking effect of the light-blocking structure.

7. The method for forming an image sensor according to claim 1, wherein: The line width of the short-line trench through hole is 0.4-0.8 microns.

8. The method for forming an image sensor according to claim 1, wherein: Forming the light blocking structure includes: Etching the semiconductor substrate according to a preset photolithography pattern to form a trench through hole; Metal material is filled in the groove through hole to form the light blocking structure.

9. The method for forming an image sensor according to claim 8, wherein: The metal material includes tungsten.

10. An image sensor, characterized in that: The image sensor is formed by the image sensor forming method as described in claims 1 to 9.

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