Image sensor and method for manufacturing the same

Abstract

The present invention discloses an image sensor and a manufacturing method thereof. The image sensor includes a circuit connection layer, an optical structure layer, and a semiconductor structure layer located between the circuit connection layer and the optical structure layer. The semiconductor structure layer has a photosensitive pixel area distributed in an array and a groove isolation structure that separates a plurality of photosensitive pixel areas. A photosensitive element is provided in the photosensitive pixel area. The groove isolation structure includes a corresponding reflective structure and a light absorbing structure. The reflective structure is located at one end of the groove isolation structure close to the optical structure layer and is used to reflect light. The light absorbing structure is located at one end of the groove isolation structure close to the circuit connection layer and is used to absorb light. The reflective structure can increase the light receiving performance of the photosensitive element, and can also avoid or reduce optical crosstalk of light near the optical structure layer. The light absorbing structure can absorb light near the circuit connection layer, thereby avoiding or reducing crosstalk of light near the circuit connection layer.

Description

Technical Field

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

[0002] An image sensor is a device that converts light signals into electrical signals. Generally, large-scale commercial image sensor chips include two categories: charge coupled device (CCD) and complementary metal oxide semiconductor (CMOS) image sensor chips.

[0003] Compared with traditional CCD sensors, CMOS image sensors have the characteristics of low power consumption, low cost and compatibility with CMOS technology, so they are increasingly widely used. Now CMOS image sensors are not only used in consumer electronics, such as miniature digital cameras (DSC), mobile phone cameras, camcorders and digital single-lens reflex cameras (DSLR), but also in automotive electronics, monitoring, biotechnology and medicine.

[0004] The pixel unit of a CMOS image sensor is the core device for the image sensor to realize photosensitivity. The most commonly used pixel unit is an active pixel structure that includes a photodiode and multiple transistors. Among these devices, the photodiode is the photosensitive unit, which realizes the collection and photoelectric conversion of light, and the other MOS transistors are the control units, which mainly realize the control of the selection, reset, signal amplification and readout of the photodiode.

[0005] CMOS image sensors can be divided into two types according to the different paths of incident light entering the photodiode: front-illuminated and back-illuminated. Front-illuminated refers to an image sensor in which incident light enters the photodiode from the side close to the circuit connection layer, while back-illuminated refers to an image sensor in which incident light enters the photodiode from the side away from the circuit connection layer.

[0006] In order to increase the area of ​​the photodiode in the CMOS image sensor and reduce the loss of incident light by the dielectric layer, we can use a back-illuminated CMOS image sensor process, that is, the incident light enters the photodiode from the back of the silicon wafer, thereby reducing the loss of incident light by the dielectric layer and improving the sensitivity of the pixel unit.

[0007] The absorption coefficient of silicon material to incident light decreases as the wavelength increases. Conventional pixel units usually use red, green, and blue primary color filter layers. Among them, red light is absorbed deepest in the silicon wafer, while blue light is shallowest. Blue light is absorbed at the position closest to the surface of the silicon wafer, and its absorption coefficient is the highest; red light enters the deepest into the silicon wafer, and its absorption coefficient is the lowest; the absorption coefficient of green light is between blue and red light, and the absorption of near-infrared light requires an absorption thickness greater than 2.3 microns. Therefore, the existing back-illuminated CMOS image sensors have poor performance in receiving red light and near-infrared light, resulting in poor light capture and imaging capabilities for dark field effects.

[0008] In order to improve the receiving performance of red light and near-infrared light, existing back-illuminated CMOS image sensors usually diverge light by thickening the photosensitive element or adding some microstructures to the photosensitive element. Although this enhances the receiving performance of the back-illuminated CMOS image sensor for red light and near-infrared light, it also increases optical crosstalk and affects imaging. Summary of the invention

[0009] In order to overcome the shortcomings and deficiencies in the prior art, an object of the present invention is to provide an image sensor and a manufacturing method thereof, so as to solve the problem of optical crosstalk in the image sensor in the prior art.

[0010] The purpose of the present invention is achieved through the following technical solutions:

[0011] The present invention provides an image sensor, comprising a circuit connection layer, an optical structure layer and a semiconductor structure layer located between the circuit connection layer and the optical structure layer, wherein the semiconductor structure layer has photosensitive pixel areas distributed in an array and a trench isolation structure that separates a plurality of the photosensitive pixel areas and penetrates the semiconductor structure layer, wherein a photosensitive element is provided in the photosensitive pixel area, and the trench isolation structure comprises a reflective structure and a light absorbing structure corresponding to each other, wherein the reflective structure is located at one end of the trench isolation structure close to the optical structure layer and is used to reflect light, and the light absorbing structure is located at one end of the trench isolation structure close to the circuit connection layer and is used to absorb light.

[0012] Furthermore, an insulating layer is provided between the circuit connection layer and the semiconductor structure layer. The circuit connection layer includes a metal interconnection layer and a first dielectric layer. The first dielectric layer is located between the metal interconnection layer and the insulating layer. One end of the light absorption structure away from the reflective structure contacts the surface of the insulating layer.

[0013] Furthermore, an insulating layer is provided between the circuit connection layer and the semiconductor structure layer, the circuit connection layer includes a metal interconnection layer and a first dielectric layer, the first dielectric layer is located between the metal interconnection layer and the insulating layer, and one end of the light absorption structure extends toward one side of the circuit connection layer and passes through the insulating layer and the first dielectric layer to contact the surface of the metal interconnection layer.

[0014] Furthermore, the height of the reflective structure is greater than half of the height of the trench isolation structure.

[0015] Furthermore, the reflective structure is made of a material having a refractive index lower than that of the semiconductor structure layer, and the light absorbing structure is made of tungsten or titanium nitride.

[0016] Furthermore, the cross section of the light absorbing structure is a plurality of segment structures spaced apart from each other or a plurality of strip structures intersecting each other.

[0017] Furthermore, the trench isolation structure also includes a protection layer structure, which is located in the semiconductor structure layer and covers the surfaces of the reflective structure and the light absorbing structure.

[0018] The present invention also provides a method for manufacturing an image sensor, the method for manufacturing the image sensor as described above, the method comprising:

[0019] forming a first trench on one side of the semiconductor substrate;

[0020] forming an insulating protection layer on the inner wall of the first trench;

[0021] Filling the first groove with a light absorbing material to form a light absorbing structure;

[0022] forming an insulating layer on the semiconductor substrate to cover the first trench, and forming a circuit connection layer on the insulating layer;

[0023] forming a second trench on a side of the semiconductor substrate away from the circuit connection layer;

[0024] forming an insulating protection layer on the inner wall of the second trench;

[0025] Filling the second groove with a reflective material to form a reflective structure, wherein the refractive index of the reflective material is lower than the refractive index of the semiconductor substrate;

[0026] A second dielectric layer is formed on the semiconductor substrate to cover the second groove, and an optical structure layer is formed on the second dielectric layer.

[0027] The present invention also provides a method for manufacturing an image sensor, the method for manufacturing the image sensor as described above, the method comprising:

[0028] forming a first trench on one side of the semiconductor substrate;

[0029] forming an insulating protection layer on the inner wall of the first trench;

[0030] Filling a dielectric filling layer in the first trench;

[0031] forming an insulating layer on the semiconductor substrate to cover the first trench, and forming a circuit connection layer on the insulating layer;

[0032] Etching the semiconductor substrate and the dielectric filling layer on a side of the semiconductor substrate away from the circuit connection layer to form a second trench;

[0033] forming an insulating protection layer on the inner wall of the second trench;

[0034] Filling the second groove with a light absorbing material to form a light absorbing structure, wherein the height of the light absorbing structure is less than half of the depth of the second groove;

[0035] Filling the second groove with a reflective material to form a reflective structure, wherein the refractive index of the reflective material is lower than the refractive index of the semiconductor substrate;

[0036] A second dielectric layer is formed on the semiconductor substrate to cover the second groove, and an optical structure layer is formed on the second dielectric layer.

[0037] The present invention also provides a method for manufacturing an image sensor, the method for manufacturing the image sensor as described above, the method comprising:

[0038] forming a first trench on one side of the semiconductor substrate;

[0039] forming an insulating protection layer on the inner wall of the first trench;

[0040] Filling a dielectric filling layer in the first trench;

[0041] Forming an insulating layer on the semiconductor substrate to cover the first trench, and forming a first dielectric layer on the insulating layer;

[0042] The first dielectric layer, the insulating layer and the dielectric filling layer are etched in the region of the semiconductor substrate corresponding to the first trench to form a second trench;

[0043] Filling the second groove with a light absorbing material to form a light absorbing structure;

[0044] Forming a metal interconnection layer on the semiconductor substrate and covering the second trench, wherein the metal interconnection layer and the first dielectric layer together form a circuit connection layer;

[0045] forming a third trench on a side of the semiconductor substrate away from the circuit connection layer;

[0046] forming an insulating protection layer on the inner wall of the third trench;

[0047] Filling the third trench with a reflective material to form a reflective structure, wherein the refractive index of the reflective material is lower than the refractive index of the semiconductor substrate;

[0048] A second dielectric layer is formed on the semiconductor substrate to cover the third groove, and an optical structure layer is formed on the second dielectric layer.

[0049] The beneficial effects of the present invention are as follows: by setting a trench isolation structure in the semiconductor structure layer, the end of the trench isolation structure close to the optical structure layer is a reflective structure with reflected light, so as to increase the light receiving performance, and can also avoid or reduce the optical crosstalk of light near the optical structure layer; the end of the trench isolation structure close to the circuit connection layer is a light absorbing structure with absorbed light, and the light absorbing structure can absorb the light incident near the circuit connection layer, thereby avoiding or reducing the crosstalk of light near the circuit connection layer structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 is a schematic diagram of the longitudinal cross-section structure of the image sensor in the first embodiment of the present invention;

[0051] Figure 2 is a schematic diagram of a cross-sectional structure of an image sensor in Embodiment 1 of the present invention;

[0052] Figure 3a-3i It is one of the structural flow charts of the method for manufacturing an image sensor in the first embodiment of the present invention;

[0053] Figures 4a-4j This is the second structural flow chart of the method for manufacturing the image sensor in the first embodiment of the present invention;

[0054] Figure 5 is a schematic diagram of the cross-sectional structure of an image sensor in Embodiment 2 of the present invention;

[0055] Figure 6 is a schematic diagram of the longitudinal cross-section structure of the image sensor in the third embodiment of the present invention;

[0056] Figures 7a-7k It is a structural flow chart of the method for manufacturing an image sensor in Embodiment 3 of the present invention. DETAILED DESCRIPTION

[0057] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation manner, structure, features and effects of the image sensor and the manufacturing method thereof proposed by the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments:

[0058] [Example 1]

[0059] Figure 1 is a schematic diagram of the longitudinal cross-sectional structure of the image sensor in the first embodiment of the present invention, Figure 2 Schematic diagram of the cross-sectional structure of the image sensor in the first embodiment of the present invention.

[0060] like Figure 1 to Figure 2 As shown, an image sensor provided by the first embodiment of the present invention includes a circuit connection layer 10, an optical structure layer 30, and a semiconductor structure layer 20 located between the circuit connection layer 10 and the optical structure layer 30. The semiconductor structure layer 20 has photosensitive pixel areas 21 distributed in an array and a trench isolation structure 22 that separates the multiple photosensitive pixel areas 21 and penetrates the semiconductor structure layer 20. The trench isolation structure 22 is a frame structure that separates the multiple photosensitive pixel areas 21. A photosensitive element (photodiode) is provided in the photosensitive pixel area 21. The trench isolation structure 22 includes a reflective structure 221 and a light absorbing structure 222 that correspond to each other. The reflective structure 221 is located at one end of the trench isolation structure 22 close to the optical structure layer 30 and is used to reflect light. The light absorbing structure 222 is located at one end of the trench isolation structure 22 close to the circuit connection layer 10 and is used to absorb light. That is, the trench isolation structure 22 is divided into two parts. The part close to the optical structure layer 30 is the reflective structure 221, and the part close to the circuit connection layer 10 is the light absorbing structure 222.

[0061] The present invention sets a trench isolation structure 22 in the semiconductor structure layer 20. The end of the trench isolation structure 22 close to the optical structure layer 30 is a reflective structure 221 with reflected light. The light is reflected between the reflective structures 221, so that the photosensitive element can receive more light, so as to increase the receiving performance of red light and near-infrared light. At the same time, it can also avoid or reduce the light from passing through the trench isolation structure 22 into other photosensitive pixel areas 21, and prevent optical crosstalk near the optical structure layer 30, that is, prevent top optical crosstalk. The end of the trench isolation structure 22 close to the circuit connection layer 10 is a light absorbing structure 222 that absorbs light. The light absorbing structure 222 can absorb light that enters the circuit connection layer 10, thereby avoiding or reducing the light from other photosensitive pixel areas 21 of the circuit connection layer 10, and preventing optical crosstalk near the circuit connection layer 10, that is, preventing bottom optical crosstalk.

[0062] The image sensor is a backside illumination (BSI) image sensor. The circuit connection layer 10 includes a metal interconnection layer 11 and a first dielectric layer 12. The metal interconnection layer 11 is used to process and transmit the information of the photosensitive element. The metal interconnection layer 11 includes a plug and a multi-layer metal wire layer. The optical structure layer 30 includes a color filter layer 31 and a microlens array structure 32. The color filter layer 31 includes three color filter layers of red (R), green (G), and blue (B) and is distributed in an array. Each color filter layer 31 corresponds to a pixel unit. The microlens array structure 32 has a focusing effect, so that the light is focused on the photosensitive element. Each pixel unit may include one pixel or multiple shared pixels. For a more detailed introduction to the back-illuminated image sensor, please refer to the prior art, which will not be repeated here.

[0063] In this embodiment, an insulating layer 40 is provided between the circuit connection layer 10 and the semiconductor structure layer 20, the first dielectric layer 12 is located between the metal interconnection layer 11 and the insulating layer 40, and the end of the light absorption structure 222 away from the reflective structure 221 is in contact with the surface of the insulating layer 40, that is, the bottom surface of the light absorption structure 222 is flush with the bottom surface of the semiconductor structure layer 20. A second dielectric layer 50 is provided between the semiconductor structure layer 20 and the optical structure layer 30, and the color filter layer 31 is provided between the second dielectric layer 50 and the microlens array structure 32.

[0064] Furthermore, the height of the reflective structure 221 is greater than half of the height of the trench isolation structure 22, and the height of the light absorption structure 222 is less than half of the height of the trench isolation structure 22. In this embodiment, the thickness of the semiconductor structure layer 20 and the height of the trench isolation structure 22 are both 2-10 um, and the width of the trench isolation structure 22 is 0.1-0.3 um.

[0065] Furthermore, the reflective structure 221 is made of a material having a refractive index lower than that of the semiconductor structure layer 20, and the light absorbing structure 222 is made of tungsten (W) or titanium nitride (TiN). Preferably, the refractive index n of the reflective structure 221 is less than 2.5, so that total reflection is formed between the reflective structure 221 and the semiconductor structure layer 20, and the reflective structure 221 can be made of oxide (OX), silicon nitride (SiN), high dielectric material or air. Of course, the light absorbing structure 222 can also be made of other light absorbing materials. In one embodiment, the light absorbing structure 222 may also include a light blocking material, such as copper (Cu) or aluminum (Al), and the light absorbing structure 222 can be used to absorb and block light.

[0066] In this embodiment, Figure 2 As shown, the cross section of the light absorption structure 222 is a continuous structure, that is, the cross section of the light absorption structure 222 is a plurality of intersecting strip structures, and there is no gap on the light absorption structure 222 around each pixel unit.

[0067] Furthermore, the trench isolation structure 22 further includes a protection layer structure 223 , and the protection layer structure 223 covers the surfaces of the reflective structure 221 and the light absorbing structure 222 .

[0068] like Figure 3a-3i As shown, this embodiment further provides a method for manufacturing an image sensor, the manufacturing method is used to manufacture the image sensor as described above, and the manufacturing method includes:

[0069] like Figure 3a As shown, a first trench 201 is formed on one side of the semiconductor substrate 20a. Specifically, the semiconductor substrate 20a has a first surface and a second surface opposite to each other, and the first trench 201 is etched and formed on the first surface of the semiconductor substrate 20a. The top view shape of the first trench 201 is the same as the top view shape of the trench isolation structure 22.

[0070] like Figure 3b As shown, an insulating protection layer 223a is formed on the inner wall of the first trench 201. Specifically, the semiconductor substrate 20a is covered with an insulating layer, the insulating layer covers the first surface of the semiconductor substrate 20a and the inner wall of the first trench 201, and then the insulating layer covering the first surface of the semiconductor substrate 20a is removed, and the insulating layer on the inner wall of the first trench 201 is retained to form the insulating protection layer 223a.

[0071] like Figure 3c As shown, a light absorbing material 222a is filled in the first trench 201 to form a light absorbing structure 222. Specifically, a layer of light absorbing material 222a is covered on the semiconductor substrate 20a, and then the light absorbing material 222a covering the first surface of the semiconductor substrate 20a is removed, and the light absorbing material 222a in the first trench 201 is retained, and the light absorbing material 222a is separated from the inner wall of the first trench 201 by an insulating protection layer 223a.

[0072] like Figure 3d and 3e As shown, an insulating layer 40 is formed on the semiconductor substrate 20a to cover the first groove 201, and then a circuit connection layer 10 is formed on the insulating layer 40. After the circuit connection layer 10 is formed, the semiconductor substrate 20a is reversed so that the side with the circuit connection layer 10 faces downward, that is, the second surface of the semiconductor substrate 20a faces upward.

[0073] like Figure 3f As shown, a second trench 202 is formed on the side of the semiconductor substrate 20a away from the circuit connection layer 10. Specifically, the second trench 202 is etched and formed on the second surface of the semiconductor substrate 20a, and the top view shape of the second trench 202 is the same as the top view shape of the trench isolation structure 22.

[0074] like Figure 3g As shown, an insulating protective layer 223a is formed on the inner wall of the second trench 202. Specifically, a dielectric layer is covered on the semiconductor substrate 20a, and the dielectric layer covers the second surface of the semiconductor substrate 20a and the inner wall of the second trench 202, and then the dielectric layer covering the second surface of the semiconductor substrate 20a is removed, and the dielectric layer on the inner wall of the second trench 202 is retained to form an insulating protective layer 223a. The insulating protective layer 223a and the insulating protective layer 223a together form a protective layer structure 223.

[0075] like Figure 3h As shown, a reflective material 221a is filled in the second trench 202 to form a reflective structure 221, the refractive index of the reflective material 221a is lower than the refractive index of the semiconductor substrate 20a, and the reflective structure 221 and the light absorbing structure 222 located in the semiconductor structure layer (20) together form the internal intermediate structure of the trench isolation structure 22. Specifically, a layer of reflective material 221a is covered on the semiconductor substrate 20a, and then the reflective material 221a covering the second surface of the semiconductor substrate 20a is removed, and the reflective material 221a in the second trench 202 is retained, and the reflective material 221a and the inner wall of the second trench 202 are separated by an insulating protective layer 223a.

[0076] like Figure 3i As shown, a second dielectric layer 50 is formed on the semiconductor substrate 20 a to cover the second trench 202 , and then an optical structure layer 30 is formed on the second dielectric layer 50 .

[0077] like Figures 4a-4j As shown, this embodiment also provides another method for manufacturing an image sensor, the manufacturing method is used to manufacture the image sensor as described above, and the manufacturing method includes:

[0078] like Figure 4a As shown, a first trench 201 is formed on one side of the semiconductor substrate 20a. Specifically, the semiconductor substrate 20a has a first surface and a second surface opposite to each other, and the first trench 201 is etched and formed on the first surface of the semiconductor substrate 20a. The top view shape of the first trench 201 is the same as the top view shape of the trench isolation structure 22.

[0079] like Figure 4b As shown, an insulating protection layer 223a is formed on the inner wall of the first trench 201. Specifically, the semiconductor substrate 20a is covered with an insulating layer, the insulating layer covers the first surface of the semiconductor substrate 20a and the inner wall of the first trench 201, and then the insulating layer covering the first surface of the semiconductor substrate 20a is removed, and the insulating layer on the inner wall of the first trench 201 is retained to form the insulating protection layer 223a.

[0080] like Figure 4cAs shown, a dielectric filling layer 222b is filled in the first trench 201. Specifically, a dielectric layer is covered on the semiconductor substrate 20a, and then the dielectric layer covering the first surface of the semiconductor substrate 20a is removed, the dielectric layer in the first trench 201 is retained and a dielectric filling layer 222b is formed, and the dielectric filling layer 222b is separated from the inner wall of the first trench 201 by an insulating protection layer 223a.

[0081] like Figure 4d-4e As shown, an insulating layer 40 is formed on the semiconductor substrate 20a to cover the first groove 201, and then a circuit connection layer 10 is formed on the insulating layer 40. After the circuit connection layer 10 is formed, the semiconductor substrate 20a is reversed so that the side with the circuit connection layer 10 faces downward, that is, the second surface of the semiconductor substrate 20a faces upward.

[0082] like Figure 4f As shown, the semiconductor substrate 20a and the dielectric filling layer 222b are etched on the side of the semiconductor substrate 20a away from the circuit connection layer 10 to form a second trench 202. Specifically, the semiconductor substrate 20a and the dielectric filling layer 222b are etched on the second surface of the semiconductor substrate 20a to form a second trench 202, the top view shape of the second trench 202 is the same as the top view shape of the trench isolation structure 22, and the second trench 202 corresponds to the first trench 201.

[0083] like Figure 4g As shown, an insulating protective layer 223a is formed on the inner wall of the second trench 202. Specifically, a dielectric layer is covered on the semiconductor substrate 20a, and the dielectric layer covers the second surface of the semiconductor substrate 20a and the inner wall of the second trench 202, and then the dielectric layer covering the second surface of the semiconductor substrate 20a is removed, and the dielectric layer on the inner wall of the second trench 202 is retained to form an insulating protective layer 223a. The insulating protective layer 223a and the insulating protective layer 223a together form a protective layer structure 223.

[0084] like Figure 4h As shown, a light absorbing material 222a is filled in the second trench 202 to form a light absorbing structure 222, and the height of the light absorbing structure 222 is less than half of the depth of the second trench 202. Specifically, a layer of light absorbing material 222a is covered on the semiconductor substrate 20a, and then the light absorbing material 222a covering the first surface of the semiconductor substrate 20a is removed, and the light absorbing material 222a at the bottom of the second trench 202 is retained, and the light absorbing material 222a is separated from the inner wall of the second trench 202 by an insulating protective layer 223a. It can be understood that the light absorbing material 222a does not completely fill the second trench 202, but only fills the lower half of the second trench 202.

[0085] like Figure 4iAs shown, a reflective material 221a is filled in the second groove 202 to form a reflective structure 221, the refractive index of the reflective material 221a is lower than the refractive index of the semiconductor substrate 20a, and the reflective structure 221 and the light absorbing structure 222 located in the semiconductor structure layer (20) together form the internal intermediate structure of the trench isolation structure 22. Specifically, a layer of reflective material 221a is covered on the semiconductor substrate 20a, and then the reflective material 221a covering the second surface of the semiconductor substrate 20a is removed, and the reflective material 221a in the second groove 202 is retained, and the reflective material 221a is separated from the inner wall of the second groove 202 by an insulating protective layer 223a. It can be understood that the reflective material 221a only fills the upper half of the second groove 202 and overlaps with the light absorbing material 222a from top to bottom.

[0086] like Figure 4j As shown, a second dielectric layer 50 is formed on the semiconductor substrate 20 a to cover the second trench 202 , and then an optical structure layer 30 is formed on the second dielectric layer 50 .

[0087] [Example 2]

[0088] Figure 5 is a schematic diagram of the cross-sectional structure of the image sensor in the second embodiment of the present invention. Figure 5 As shown, the image sensor provided by the second embodiment of the present invention is the same as that provided by the first embodiment ( Figures 1 to 4j The image sensor in is basically the same, the difference is that, in this embodiment, the cross-section of the light absorption structure 222 is a segmented structure, and a plurality of gaps are provided on the light absorption structure 222, that is, the cross-section of the light absorption structure 222 is a plurality of segment structures spaced apart from each other, and the light absorption structure 222 around each pixel unit is composed of a plurality of independent columnar structures spaced apart from each other.

[0089] It should be understood by those skilled in the art that the rest of the structure and working principle of this embodiment are the same as those of the first embodiment and will not be described in detail here.

[0090] [Example 3]

[0091] Figure 6 FIG. 1 is a schematic diagram of the longitudinal cross-sectional structure of the image sensor in the third embodiment of the present invention. Figure 6 As shown, the image sensor provided by the third embodiment of the present invention is the same as that provided by the first embodiment ( Figures 1 to 4j ) is substantially the same as the image sensor in FIG. 1 , except that, in this embodiment, one end of the light absorption structure 222 extends toward one side of the circuit connection layer 10 and passes through the insulating layer 40 and the first dielectric layer 12 to contact the surface of the metal interconnection layer 11. In this embodiment, the height of the trench isolation structure 22 is the sum of the thicknesses of the semiconductor structure layer 20, the insulating layer 40 and the first dielectric layer 12, that is, one end of the trench isolation structure 22 is inserted into the circuit connection layer 10.

[0092] Compared with the first embodiment, the length of the trench isolation structure 22 is increased, and a part of the light absorption structure 222 is in the semiconductor structure layer 20, and a part passes through the insulating layer 40 into the circuit connection layer 10, thereby having a better effect of preventing light crosstalk.

[0093] like Figure 7a-7k As shown, this embodiment further provides a method for manufacturing an image sensor, the manufacturing method is used to manufacture the image sensor as described above, and the manufacturing method includes:

[0094] like Figure 7a As shown, a first trench 201 is formed on one side of the semiconductor substrate 20a. Specifically, the semiconductor substrate 20a has a first surface and a second surface opposite to each other, and the first trench 201 is etched and formed on the first surface of the semiconductor substrate 20a. The top view shape of the first trench 201 is the same as the top view shape of the trench isolation structure 22.

[0095] like Figure 7b As shown, an insulating protection layer 223a is formed on the inner wall of the first trench 201. Specifically, the semiconductor substrate 20a is covered with an insulating layer, the insulating layer covers the first surface of the semiconductor substrate 20a and the inner wall of the first trench 201, and then the insulating layer covering the first surface of the semiconductor substrate 20a is removed, and the insulating layer on the inner wall of the first trench 201 is retained to form the insulating protection layer 223a.

[0096] like Figure 7c As shown, a dielectric filling layer 222b is filled in the first trench 201. Specifically, a dielectric layer is covered on the semiconductor substrate 20a, and then the dielectric layer covering the first surface of the semiconductor substrate 20a is removed, and the dielectric layer in the first trench 201 is retained to form a dielectric filling layer 222b.

[0097] like Figure 7d As shown, an insulating layer 40 is formed on the semiconductor substrate 20 a to cover the first trench 201 , and then a first dielectric layer 12 is formed on the insulating layer 40 .

[0098] like Figure 7e As shown, the first dielectric layer 12, the insulating layer 40 and the dielectric filling layer 222b are etched in the region of the semiconductor substrate 20a corresponding to the first trench 201 to form a second trench 202. Specifically, the first dielectric layer 12, the insulating layer 40 and the dielectric filling layer 222b are etched on the first surface of the semiconductor substrate 20a to form a second trench 202, the top view shape of the second trench 202 is the same as the top view shape of the trench isolation structure 22, the second trench 202 corresponds to the first trench 201, and the first trench 201 becomes a part of the second trench 202.

[0099] like Figure 7f As shown, a light absorbing material 222a is filled in the second groove 202 to form a light absorbing structure 222. Specifically, a layer of light absorbing material 222a is covered on the semiconductor substrate 20a, and then the light absorbing material 222a covering the first surface of the semiconductor substrate 20a is removed, and the light absorbing material 222a in the first groove 201 and the second groove 202 is retained, and the light absorbing material 222a is separated from the inner wall of the first groove 201 by the insulating protection layer 223a, and the light absorbing material 222a is in direct contact with the first dielectric layer 12 and the insulating layer 40.

[0100] like Figure 7g As shown, a metal interconnection layer 11 is formed on the semiconductor substrate 20a and covers the second groove 202. The metal interconnection layer 11 and the first dielectric layer 12 together form a circuit connection layer 10. After the metal interconnection layer 11 is manufactured, the semiconductor substrate 20a is turned over so that the side with the circuit connection layer 10 faces downward, that is, the second surface of the semiconductor substrate 20a faces upward.

[0101] like Figure 7h As shown, a third trench 203 is formed on the side of the semiconductor substrate 20a away from the circuit connection layer 10. Specifically, the third trench 203 is etched and formed on the second surface of the semiconductor substrate 20a, and the top view shape of the third trench 203 is the same as the top view shape of the trench isolation structure 22, and the third trench 203 corresponds to the second trench 202.

[0102] like Figure 7i As shown, an insulating protective layer 223a is formed on the inner wall of the third trench 203. Specifically, a dielectric layer is covered on the semiconductor substrate 20a, and the dielectric layer covers the second surface of the semiconductor substrate 20a and the inner wall of the third trench 203, and then the dielectric layer covering the second surface of the semiconductor substrate 20a is removed, and the dielectric layer on the inner wall of the third trench 203 is retained to form an insulating protective layer 223a. The insulating protective layer 223a located in the semiconductor structure layer (20) and the insulating protective layer 223a together form the internal intermediate structure of the protective layer structure 223.

[0103] like Figure 7j As shown, a reflective material 221a is filled in the third trench 203 to form a reflective structure 221, the refractive index of the reflective material 221a is lower than the refractive index of the semiconductor substrate 20a, and the reflective structure 221 and the light absorbing structure 222 jointly form a trench isolation structure 22. Specifically, a layer of reflective material 221a is covered on the semiconductor substrate 20a, and then the reflective material 221a covering the second surface of the semiconductor substrate 20a is removed, and the reflective material 221a in the third trench 203 is retained, and the reflective material 221a and the inner wall of the third trench 203 are separated by an insulating protective layer 223a.

[0104] like Figure 7k As shown, a second dielectric layer 50 is formed on the semiconductor substrate 20 a to cover the third trench 203 , and then an optical structure layer 30 is formed on the second dielectric layer 50 .

[0105] It should be understood by those skilled in the art that the rest of the structure and working principle of this embodiment are the same as those of the first embodiment and will not be described in detail here.

[0106] In this document, the directional words such as up, down, left, right, front, and back are defined by the positions of the structures in the drawings and the positions of the structures relative to each other, just for the sake of clarity and convenience in expressing the technical solution. It should be understood that the use of the directional words should not limit the scope of protection claimed in this application. It should also be understood that the terms "first" and "second" used in this document are only used to distinguish names and are not used to limit quantity and order.

[0107] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modifications to the technical contents disclosed above without departing from the scope of the technical solution of the present invention, which are equivalent embodiments of equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. An image sensor, characterized in that: The invention comprises a circuit connection layer (10), an optical structure layer (30), and a semiconductor structure layer (20) located between the circuit connection layer (10) and the optical structure layer (30), wherein the semiconductor structure layer (20) has photosensitive pixel areas (21) distributed in an array and a trench isolation structure (22) separating a plurality of the photosensitive pixel areas (21) and penetrating the semiconductor structure layer (20), wherein the photosensitive pixel areas (21) are provided with photosensitive elements, and the trench isolation structure (22) comprises mutually corresponding reflective structures (22 1) and a light absorbing structure (222), the reflecting structure (221) is located at one end of the trench isolation structure (22) close to the optical structure layer (30) and is used to reflect light, the light absorbing structure (222) is located at one end of the trench isolation structure (22) close to the circuit connection layer (10) and is used to absorb light, the height of the reflecting structure (221) is greater than half of the height of the trench isolation structure (22), and the reflecting structure (221) is made of a material having a refractive index lower than the refractive index of the semiconductor structure layer (20).

2. The image sensor according to claim 1, characterized in that An insulating layer (40) is provided between the circuit connection layer (10) and the semiconductor structure layer (20); the circuit connection layer (10) comprises a metal interconnection layer (11) and a first dielectric layer (12); the first dielectric layer (12) is located between the metal interconnection layer (11) and the insulating layer (40); and one end of the light absorption structure (222) away from the reflective structure (221) contacts the surface of the insulating layer (40).

3. The image sensor according to claim 1, characterized in that An insulating layer (40) is provided between the circuit connection layer (10) and the semiconductor structure layer (20); the circuit connection layer (10) comprises a metal interconnection layer (11) and a first dielectric layer (12); the first dielectric layer (12) is located between the metal interconnection layer (11) and the insulating layer (40); one end of the light absorption structure (222) extends toward one side of the circuit connection layer (10) and passes through the insulating layer (40) and the first dielectric layer (12) to contact the surface of the metal interconnection layer (11).

4. The image sensor according to claim 1, characterized in that The light absorption structure (222) is made of tungsten or titanium nitride.

5. The image sensor according to claim 1, characterized in that The cross section of the light absorption structure (222) is a plurality of segment structures spaced apart from each other or a plurality of strip structures intersecting each other.

6. The image sensor according to claim 1, characterized in that: The trench isolation structure (22) also includes a protective layer structure (223), which is located in the semiconductor structure layer (20) and covers the surfaces of the reflective structure (221) and the light absorption structure (222).

7. A method for manufacturing an image sensor, characterized in that: The manufacturing method is used to manufacture the image sensor according to any one of claims 1 to 6, and the manufacturing method comprises: forming a first trench (201) on one side of a semiconductor substrate (20a); forming an insulating protection layer (223a) on the inner wall of the first groove (201); Filling the first groove (201) with a light absorbing material (222a) to form a light absorbing structure (222); An insulating layer (40) is formed on the semiconductor substrate (20a) to cover the first groove (201), and a circuit connection layer (10) is formed on the insulating layer (40); forming a second groove (202) on a side of the semiconductor substrate (20a) away from the circuit connection layer (10); forming an insulating protection layer (223a) on the inner wall of the second groove (202); Filling a reflective material (221a) in the second groove (202) to form a reflective structure (221), the refractive index of the reflective material (221a) being lower than the refractive index of the semiconductor substrate (20a), and the second groove (202) corresponding to the first groove (201); A second dielectric layer (50) is formed on the semiconductor substrate (20a) to cover the second groove (202), and an optical structure layer (30) is formed on the second dielectric layer (50).

8. A method for manufacturing an image sensor, characterized in that: The manufacturing method is used to manufacture the image sensor according to any one of claims 1 to 6, and the manufacturing method comprises: forming a first trench (201) on one side of a semiconductor substrate (20a); forming an insulating protection layer (223a) on the inner wall of the first groove (201); Filling a dielectric filling layer (222b) in the first groove (201); An insulating layer (40) is formed on the semiconductor substrate (20a) to cover the first groove (201), and a circuit connection layer (10) is formed on the insulating layer (40); Etching the semiconductor substrate (20a) and the dielectric filling layer (222b) on a side of the semiconductor substrate (20a) away from the circuit connection layer (10) to form a second trench (202); forming an insulating protection layer (223a) on the inner wall of the second groove (202); Filling the second groove (202) with a light absorbing material (222a) to form a light absorbing structure (222), wherein the height of the light absorbing structure (222) is less than half of the depth of the second groove (202); Filling a reflective material (221a) in the second groove (202) to form a reflective structure (221), wherein the refractive index of the reflective material (221a) is lower than the refractive index of the semiconductor substrate (20a); A second dielectric layer (50) is formed on the semiconductor substrate (20a) to cover the second groove (202), and an optical structure layer (30) is formed on the second dielectric layer (50).

9. A method for manufacturing an image sensor, characterized in that: The manufacturing method is used to manufacture the image sensor according to any one of claims 1 to 6, and the manufacturing method comprises: forming a first trench (201) on one side of a semiconductor substrate (20a); forming an insulating protection layer (223a) on the inner wall of the first groove (201); Filling a dielectric filling layer (222b) in the first trench (201); An insulating layer (40) is formed on the semiconductor substrate (20a) to cover the first trench (201), and a first dielectric layer (12) is formed on the insulating layer (40); Etching the first dielectric layer (12), the insulating layer (40) and the dielectric filling layer (222b) in a region of the semiconductor substrate (20a) corresponding to the first trench (201) to form a second trench (202); Filling the second groove (202) with a light absorbing material (222a) to form a light absorbing structure (222); A metal interconnection layer (11) is formed on the semiconductor substrate (20a) to cover the second trench (202), wherein the metal interconnection layer (11) and the first dielectric layer (12) together form a circuit connection layer (10); forming a third trench (203) on a side of the semiconductor substrate (20a) away from the circuit connection layer (10); forming an insulating protection layer (223a) on the inner wall of the third groove (203); Filling the third groove (203) with a reflective material (221a) to form a reflective structure (221), wherein the refractive index of the reflective material (221a) is lower than the refractive index of the semiconductor substrate (20a); A second dielectric layer (50) is formed on the semiconductor substrate (20a) to cover the third groove (203), and an optical structure layer (30) is formed on the second dielectric layer (50).

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