Image sensor and method for manufacturing the same

Abstract

The present invention provides an image sensor and a manufacturing method thereof, the manufacturing method comprising: providing a first substrate; forming a groove in the peripheral circuit area; forming a metal barrier layer; forming a metal layer; patterning and etching the first metal layer and the first metal barrier layer outside the groove to form a stacked second metal barrier layer and a second metal layer. The metal grid and the metal wiring portion both include the second metal barrier layer and the second metal layer stacked in sequence in a direction away from the first surface. The second metal layer in the metal grid, the second metal layer in the metal wiring portion, and the first metal layer in the groove of the present invention share the same metal layer, reducing the process steps; the second metal barrier layer in the metal grid, the second metal barrier layer in the metal wiring portion, and the first metal barrier layer in the groove also only require one metal barrier layer formation process, reducing the process steps.

Description

Technical Field

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

[0002] The light of the back-illuminated (BSI) image sensor enters the substrate from the back side of the substrate rather than the front side, which reduces light reflection and achieves higher photoelectric conversion efficiency. BSI image sensors can capture more image signals than front-illuminated image sensors. At present, BSI image sensors integrate the logic operation chip and the pixel (photodiode) array chip in three dimensions through silicon vias (TSV). On the one hand, while maintaining the chip volume, the sensor array size and area are increased. On the other hand, the metal interconnection between functional chips is greatly shortened, reducing heat, power consumption, and delay, and improving chip performance.

[0003] In BSI image sensors, a metal grid is set up, and the light-proof property of the metal grid is used to prevent light crosstalk between different pixels (photodiodes). As the BSI pixel size continues to shrink, in order to ensure sufficient light input, the line width of the metal grid is also continuously reduced, and the process difficulty increases; at the same time, the continuous miniaturization of chip size has put forward higher requirements for the area optimization of the back lead structure, and the process complexity increases. Summary of the invention

[0004] The object of the present invention is to provide an image sensor and a manufacturing method thereof, which can reduce process complexity and process steps.

[0005] The present invention provides a method for manufacturing an image sensor, comprising:

[0006] Providing a first substrate, the first substrate comprising a pixel region and a peripheral circuit region; the first substrate having a first surface and a second surface opposite to each other, a first insulating layer being formed on one side of the second surface of the first substrate, and a first conductive layer being embedded in the first insulating layer;

[0007] forming a groove in the peripheral circuit region, wherein the groove extends from the first surface into the first substrate and exposes the first conductive layer;

[0008] forming a metal barrier layer, the metal barrier layer comprising a first metal barrier layer covering the sidewalls and the bottom wall of the trench and the exposed surface of the first conductive layer, the first metal barrier layer also extending to cover the first surface outside the trench;

[0009] forming a metal layer, the metal layer comprising a first metal layer covering a surface of the first metal barrier layer in the groove and filling the groove, the first metal layer also extending to cover a surface of the first metal barrier layer outside the groove;

[0010] The first metal layer and the first metal barrier layer at the periphery of the groove are pattern-etched to form a second metal barrier layer covering the first surface and a second metal layer covering the second metal barrier layer at the periphery of the groove, so as to form a metal grid in the pixel area and a metal wiring portion connected to the first metal layer in the peripheral circuit area; the metal grid and the metal wiring portion both include the second metal barrier layer and the second metal layer stacked in sequence in a direction away from the first surface;

[0011] Furthermore, the step of patterning and etching the first metal layer and the first metal barrier layer around the trench includes:

[0012] Using a first process to etch the first metal barrier layer at the periphery of the trench as an etch stop layer, the first metal layer extending and covering the surface of the first metal barrier layer at the periphery of the trench is etched to form a second metal layer on the surface of the first metal barrier layer at the periphery of the trench;

[0013] A second process is adopted to etch the first metal barrier layer extending to cover the first surface of the periphery of the trench using the second metal layer as a mask to form a second metal barrier layer on the first surface of the periphery of the trench.

[0014] Furthermore, the first conductive layer includes a transverse conductive layer and a longitudinal conductive layer, and a width of the longitudinal conductive layer in a direction parallel to the first surface is smaller than a width of the transverse conductive layer;

[0015] The production method further comprises:

[0016] A shallow trench is formed on one side of the second surface of the first substrate, the first insulating layer fills the shallow trench to form a shallow trench isolation structure, the shallow trench isolation structure forms the longitudinal conductive layer having one end electrically connected to at least one of the transverse conductive layers, and the end of the longitudinal conductive layer not connected to the transverse conductive layer is located in the shallow trench isolation structure;

[0017] forming an opening, wherein the opening extends from the first surface and is inserted into the first substrate and communicates with the shallow groove;

[0018] After forming a protection layer on the sidewall of the opening, the first insulating layer and / or the protection layer between the bottom of the opening and the vertical conductive layer are removed to expose the vertical conductive layer to form the groove.

[0019] Furthermore, the production method also includes:

[0020] forming a deep trench in the pixel region, wherein the deep trench extends from the first surface of the first substrate and is inserted into the interior of the first substrate;

[0021] A first dielectric layer is formed, wherein the first dielectric layer fills the deep trench to form a deep trench isolation structure, and the first dielectric layer also covers the first surface of the first substrate.

[0022] Furthermore, the deep trench isolation structures are arranged in an array, the pixel units of the image sensor are arranged between the deep trench isolation structures, and the projection of the metal grid on the first substrate covers the projection of the deep trench isolation structure on the first substrate.

[0023] Furthermore, the metal barrier layer is titanium nitride, and the metal layer is tungsten.

[0024] The present invention also provides an image sensor, comprising:

[0025] A first substrate, the first substrate comprising a pixel region and a peripheral circuit region; the first substrate having a first surface and a second surface opposite to each other, a first insulating layer is formed on one side of the second surface of the first substrate, and a first conductive layer is embedded in the first insulating layer;

[0026] A groove located in the peripheral circuit area, the groove extending from the first surface into the first substrate and exposing the first conductive layer;

[0027] A metal barrier layer and a metal layer, the metal barrier layer comprising a first metal barrier layer and a second metal barrier layer, the first metal barrier layer covering the sidewalls and bottom wall of the trench, and the exposed surface of the first conductive layer, the second metal barrier layer being formed by patterning and etching the first metal barrier layer extending to cover the first surface of the periphery of the trench; the metal layer comprising a first metal layer and a second metal layer, the first metal layer covering the surface of the first metal barrier layer in the trench and filling the trench, the second metal layer being formed by patterning and etching the first metal layer extending to cover the surface of the first metal barrier layer of the periphery of the trench;

[0028] A metal grid located in the pixel area and a metal connection portion located in the peripheral circuit area and connected to the first metal layer, wherein the metal grid and the metal connection portion both include the second metal barrier layer and the second metal layer stacked in sequence in a direction away from the first surface.

[0029] Furthermore, the first conductive layer includes a transverse conductive layer and a longitudinal conductive layer, and a width of the longitudinal conductive layer in a direction parallel to the first surface is smaller than a width of the transverse conductive layer;

[0030] A shallow trench isolation structure is formed on one side of the second surface of the first substrate, and the shallow trench isolation structure forms the longitudinal conductive layer having one end electrically connected to at least one of the transverse conductive layers, the end of the longitudinal conductive layer not connected to the transverse conductive layer, the metal barrier layer between the longitudinal conductive layer and the first metal layer, and the end of the first metal layer close to the longitudinal conductive layer are all located in the shallow trench isolation structure, and the first metal layer is electrically connected to the transverse conductive layer through the metal barrier layer between the longitudinal conductive layer and the first metal layer and the longitudinal conductive layer.

[0031] Furthermore, the image sensor further includes:

[0032] A deep trench isolation structure is located in the pixel area, wherein the deep trench isolation structure extends from the first surface of the first substrate and is inserted into the interior of the first substrate; the deep trench isolation structures are arranged in an array, the pixel units of the image sensor are arranged between the deep trench isolation structures, and the projection of the metal grid on the first substrate covers the projection of the deep trench isolation structure on the first substrate.

[0033] Furthermore, the image sensor further includes:

[0034] A second substrate, a second insulating layer located on the second substrate, and a second conductive layer embedded in the second insulating layer;

[0035] The first insulating layer and the second insulating layer are bonded together.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The present invention provides an image sensor and a manufacturing method thereof, the manufacturing method comprising: providing a first substrate; forming a groove in the peripheral circuit area; forming a metal barrier layer; forming a metal layer; patterning and etching the first metal layer and the first metal barrier layer outside the groove to form a stacked second metal barrier layer and a second metal layer. The metal grid and the metal wiring portion both include the second metal barrier layer and the second metal layer stacked in sequence in a direction away from the first surface. The second metal layer in the metal grid, the second metal layer in the metal wiring portion, and the first metal layer in the groove of the present invention share the same metal layer, reducing the process steps; the second metal barrier layer in the metal grid, the second metal barrier layer in the metal wiring portion, and the first metal barrier layer in the groove also only require one metal barrier layer formation process, reducing the process steps. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 FIG. 4 is a flow chart of a method for manufacturing an image sensor according to an embodiment of the present invention.

[0039] Figure 2 A schematic diagram of the method for manufacturing an image sensor according to an embodiment of the present invention after providing a first substrate.

[0040] Figure 3 It is a schematic diagram of the method for manufacturing an image sensor after forming a groove according to an embodiment of the present invention.

[0041] Figure 4 It is a schematic diagram of the method for manufacturing an image sensor after forming a metal layer according to an embodiment of the present invention.

[0042] Figure 5 It is a schematic diagram of the method for manufacturing an image sensor according to an embodiment of the present invention after patterning the metal layer and the metal barrier layer.

[0043] The reference numerals are as follows:

[0044] 10-first wafer; 11-first substrate; 12-first insulating layer; A-first conductive layer; 13-lateral conductive layer; 14-vertical conductive layer; 15-deep trench isolation structure; 16-first dielectric layer; 17-shallow trench isolation; f1-first surface; f2-second surface; V-groove; I-pixel area; II-peripheral circuit area;

[0045] 20-second wafer; 21-second substrate; 22-second insulating layer; 23-second conductive layer; 30a-metal connection portion; 30b-metal grid; 30c-metal shielding layer; 31-protective layer; 32-metal barrier layer; 32a-first metal barrier layer; 32b-second metal barrier layer; 33-metal layer; 33a-first metal layer; 33b-second metal layer; 34-passivation layer. DETAILED DESCRIPTION

[0046] Based on the above research, an embodiment of the present invention provides an image sensor and a method for manufacturing the same. The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer according to the following description. It should be noted that the drawings are all in a very simplified form and use an inaccurate scale, which is only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0047] In the drawings, the sizes of layers, regions, elements and their relative sizes may be exaggerated for clarity. Like reference numerals denote like elements throughout.

[0048] It should be understood that when an element or layer is referred to as "on ...", "adjacent to ...", "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on ...", "directly adjacent to ...", "directly connected to" or "directly coupled to" other elements or layers, there is no intervening element or layer. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present application, the first element, component, region, layer or part discussed below can be represented as the second element, component, region, layer or part. And when the second element, component, region, layer or part is discussed, it does not indicate that the present application necessarily has the first element, component, region, layer or part.

[0049] Spatially relative terms such as "under", "beneath", "below", "under", "above", "above", etc., may be used here for convenience of description to describe the relationship between an element or feature shown in the figure and other elements or features. It should be understood that in addition to the orientation shown in the figure, the spatial relationship terms are intended to also include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is turned over, then the elements or features described as "under other elements" or "under it" or "under it" will be oriented as "on" other elements or features. Therefore, the exemplary terms "under" and "under" may include both upper and lower orientations. The device can be oriented otherwise (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0050] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present application. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0051] The embodiment of the present invention provides a method for manufacturing an image sensor, such as Figure 1 As shown, including:

[0052] Step S1, providing a first substrate, wherein the first substrate includes a pixel area and a peripheral circuit area; the first substrate has a first surface and a second surface opposite to each other, a first insulating layer is formed on one side of the second surface of the first substrate, and a first conductive layer is embedded in the first insulating layer;

[0053] Step S2, forming a groove in the peripheral circuit area, wherein the groove extends from the first surface into the interior of the first substrate and exposes the first conductive layer;

[0054] Step S3, forming a metal barrier layer, wherein the metal barrier layer includes a first metal barrier layer covering the sidewalls and the bottom wall of the trench and the exposed surface of the first conductive layer, and the first metal barrier layer also extends to cover the first surface outside the trench;

[0055] Step S4, forming a metal layer, wherein the metal layer includes a first metal layer covering a surface of the first metal barrier layer in the groove and filling the groove, and the first metal layer also extends to cover a surface of the first metal barrier layer outside the groove;

[0056] Step S5, graphically etching the first metal layer and the first metal barrier layer around the groove to form a second metal barrier layer covering the first surface around the groove and a second metal layer covering the second metal barrier layer, so as to form a metal grid in the pixel area and a metal wiring portion electrically connected to the first metal layer in the peripheral circuit area; the metal grid and the metal wiring portion both include the second metal barrier layer and the second metal layer stacked in sequence in a direction away from the first surface.

[0057] Combine the following Figures 2 to 5 Each step of the method for manufacturing an image sensor according to an embodiment of the present invention is described in detail.

[0058] Step S1: Figure 2As shown, a first wafer 10 is provided, the first wafer 10 includes a first substrate 11, the first substrate 11 includes a pixel area I and a peripheral circuit area II, and the peripheral circuit area II includes a logic area, for example. The first substrate 11 has a first surface f1 and a second surface f2 opposite to each other; a plurality of light sensing areas are formed in the pixel area, and the light sensing areas are used to sense incident light entering the pixel area from the first surface f1. A first insulating layer 12 is formed on the second surface f2, and at least one first conductive layer A is embedded in the first insulating layer 12. In one example, the first conductive layer A includes at least one transverse conductive layer 13 and at least one longitudinal conductive layer 14, and the width of the longitudinal conductive layer 14 in the direction parallel to the first surface is less than the width of the transverse conductive layer 13. In another example, the first conductive layer A includes at least one transverse conductive layer 13, and may not include a longitudinal conductive layer 14. The first substrate 11 may include a semiconductor material, and may be a single-layer structure or a multi-layer structure. The first substrate 11 may be a semiconductor material such as Si, SiGe, SiGeC, SiC, GaAs, InAs, InP and other III / V or II / VI compound semiconductors. It may also include a layered substrate such as, for example, Si / SiGe, Si / SiC, silicon on insulator (SOI) or silicon germanium on insulator.

[0059] A deep trench may also be formed in the first substrate 11, and the deep trench extends from the first surface f1 of the first substrate into the first substrate 11. Exemplarily, the deep trenches may be arranged in an array. A first dielectric layer 16 may also be formed on one side of the first surface f1 of the first substrate, and the first dielectric layer 16 fills the deep trench to form a deep trench isolation structure (DTI) 15. The pixel units of the image sensor are arranged between the deep trench isolation structures 15, and the first dielectric layer 16 also covers the first surface f1 of the first substrate 11. The deep trench isolation structure (DTI) 16 is used to prevent optical and electrical interference between adjacent pixel units in the first substrate 11.

[0060] A shallow trench is also formed on one side of the second surface f2 of the first substrate 11, and the first insulating layer 12 covers the second surface f2 of the first substrate 11 and fills the shallow trench to form a shallow trench isolation structure (STI) 17. The shallow trench isolation structure (STI) 17 and the first insulating layer 12 can be formed simultaneously or in steps. The first insulating layer 12 is various insulating materials known to those skilled in the art, and can be a single-layer structure or a multi-layer structure.

[0061] In one example, the shallow trench isolation structure (STI) 17 is not provided in the first substrate 11, and the vertical conductive layer 14 is formed in the first insulating layer 12 and electrically connected to the horizontal conductive layer. One end of the vertical conductive layer 14 along a direction perpendicular to the first surface of the first substrate 11 is connected to the horizontal conductive layer, and the other end is in contact with the second surface f2 of the first substrate 11.

[0062] In another example, a shallow trench isolation structure (STI) 17 is provided in the first substrate 11, and the longitudinal conductive layer 14 is formed in the first insulating layer 12 of the shallow trench isolation structure (STI) 17, and the longitudinal conductive layer 14 is electrically connected to at least one of the transverse conductive layers 13 along one end perpendicular to the first surface direction of the first substrate 11, and the end not connected to the transverse conductive layer 13 is located in the shallow trench isolation structure 17, that is, the other end extends into the shallow trench isolation structure (STI) 17 or extends to a side surface of the shallow trench isolation structure (STI) 17 close to the first surface f1.

[0063] The manufacturing method also includes: providing a second wafer 20, the second wafer 20 includes a second substrate 21, a second insulating layer 22 is formed on one side surface of the second substrate 21 along the thickness direction, and a second conductive layer 23 is embedded in the second insulating layer 22. The first insulating layer 12 and the second insulating layer 22 form a stack (bonding) of the first wafer 10 and the second wafer 20 by melt bonding, hybrid bonding, etc. The image sensor of the embodiment of the present invention does not limit the number of stacked wafers, and can form a stack of two or more wafers. The top first wafer (e.g., pixel wafer) can be thinned as needed.

[0064] Step S2: Figure 3 As shown, a trench V is formed by processes such as exposure, development, and etching, and the trench V penetrates at least part of the thickness of the first substrate 11 from the first surface. Specifically, in one example, an opening (not shown) may be formed first, and the opening extends from the upper surface of the first dielectric layer 16 to the inside of the first substrate 11 and communicates with the shallow trench; after forming a protective layer 31 on the sidewall of the opening, the first insulating layer 12 between the bottom of the opening and the vertical conductive layer 14 and / or the protective layer exposes the vertical conductive layer 14 to form the trench V. In another example, in a structure where a shallow trench isolation structure (STI) 17 is not provided in the first substrate 11, the trench V penetrates the entire thickness of the first substrate 11 and exposes the vertical conductive layer 14. Next, a protective layer 31 is formed, and the protective layer 31 covers the sidewall and bottom of the trench V, and the protective layer 31 at the bottom of the trench is removed. The protective layer 31 is various insulating materials known to those skilled in the art, and may be a single-layer structure or a multi-layer structure, such as a silicon oxide layer or a silicon nitride layer.

[0065] Step S3: Figure 4 and Figure 5 As shown, a metal barrier layer 32 is formed, and the metal barrier layer 32 includes a first metal barrier layer 32a covering the sidewall and bottom wall of the groove and the exposed surface of the longitudinal conductive layer 14, and the first metal barrier layer 32a also extends to cover the first surface of the outer periphery of the groove; specifically, the metal barrier layer 32 covers the surface of the first dielectric layer 16 and the protective layer 31. The metal barrier layer is made of metal. Since the metal material has good density and can play the role of etching barrier, the material of the metal barrier layer can be tantalum nitride, titanium nitride, tantalum nitride, tantalum nitride carbide, titanium and tantalum, etc., which are well known to those skilled in the art. Preferably, the metal barrier layer is titanium nitride, and the formation process can be chemical vapor deposition or physical vapor deposition. The function of the metal barrier layer 32 is to prevent the corrosion of the protective layer by the gas in the subsequent formation of the metal layer, and also to prevent the metal ions in the metal layer from diffusing into the surrounding protective layer 31 and the first substrate 11; the metal barrier layer 32 also serves as an etching stop layer for the subsequent etching of the metal layer 33.

[0066] Step S4: Figure 4 and Figure 5 As shown, a metal layer 33 is formed, the metal layer 33 includes a first metal layer 33a covering the surface of the first metal barrier layer 32a of the groove and filling the groove, the first metal layer 33a also extends to cover the surface of the first metal barrier layer outside the groove, and the first metal layer 33a is electrically connected to the transverse conductive layer 13 through the metal barrier layer 32 between the longitudinal conductive layer 14 and the first metal layer 33a and the longitudinal conductive layer 14. The metal layer 33 is any one of copper, tungsten or aluminum or other suitable materials that can play a conductive role. The metal layer 33 on the surface of the first wafer 10 is flattened, and a passivation layer 34 is formed on the surface of the metal layer 33.

[0067] Step S5: Figure 4 and Figure 5As shown, the first metal layer and the first metal barrier layer at the periphery of the trench are pattern-etched to form a second metal barrier layer 32b covering the first surface at the periphery of the trench and a second metal layer 33b covering the second metal barrier layer 32b. The step of patterning and etching the first metal layer and the first metal barrier layer at the periphery of the groove includes: using the first process to etch the first metal barrier layer at the periphery of the groove as an etching stop layer to extend and cover the surface of the first metal barrier layer at the periphery of the groove to form a second metal layer 33b on the surface of the first metal barrier layer at the periphery of the groove; using the second metal layer 33b as a mask to etch the first metal barrier layer extending and covering the first surface at the periphery of the groove to form a second metal barrier layer 32b on the first surface at the periphery of the groove, so as to simultaneously form a metal grid 30b in the pixel area I, a metal connection portion 30a connected to the first metal layer 33a in the peripheral circuit area II, and a metal shielding layer 30c between the pixel area I and the peripheral circuit area II; the metal grid 30b, the metal connection portion 30a and the metal shielding layer 30c all include the second metal barrier layer 32b and the second metal layer 33b stacked in sequence in a direction away from the first surface. The first process and the second process can be the same process or different processes.

[0068] The metal connection part 30a, the first metal layer 33a, the metal barrier layer 32 between the longitudinal conductive layer 14 and the first metal layer 33a, the longitudinal conductive layer 14 and the transverse conductive layer 13 are electrically connected in sequence, and the electrical signal of the first conductive layer is led out to the surface of the first wafer 10. The first metal barrier layer 32a and the first metal layer 33a formed in the groove serve as a back wiring structure, which integrates two or more devices in a three-dimensional direction to achieve electrical connection. At the same time, the metal grid 30b and the metal shielding layer 30c outside the peripheral circuit area share the metal barrier layer and the metal layer in the back wiring structure, and no additional process is required to form the metal grid 30b and the metal shielding layer 30c separately.

[0069] In the embodiment of the present invention, the material of the metal layer 33 is any one of copper, tungsten or aluminum or other suitable conductive materials. When the material of the metal layer 33 is tungsten, it can be formed by a chemical vapor deposition (CVD) process, when the material of the metal layer is aluminum, it can be formed by a physical vapor deposition process, and when the material of the metal layer 33 is copper, it can be formed by an electroplating process.

[0070] In the image sensor and the manufacturing method thereof provided by the present invention, the manufacturing method includes: providing a first substrate; forming a groove in the peripheral circuit area; forming a metal barrier layer; forming a metal layer; patterning and etching the first metal layer and the first metal barrier layer outside the groove to form a stacked second metal barrier layer and a second metal layer. The metal grid and the metal wiring portion both include the second metal barrier layer and the second metal layer stacked in sequence in a direction away from the first surface. The second metal layer in the metal grid, the second metal layer in the metal wiring portion, and the first metal layer in the groove of the present invention share the same metal layer, reducing the process steps; the second metal barrier layer in the metal grid, the second metal barrier layer in the metal wiring portion, and the first metal barrier layer in the groove also only require one metal barrier layer formation process, reducing the process steps.

[0071] The embodiment of the present invention further provides an image sensor, such as Figure 2 and Figure 5 As shown, including:

[0072] A first substrate 11, wherein the first substrate 11 includes a pixel region and a peripheral circuit region; the first substrate 11 has a first surface and a second surface opposite to each other, wherein a plurality of light sensing regions are formed in the pixel region, wherein the light sensing regions are used to sense incident light entering the pixel region from the first surface; a first insulating layer 12 is formed on one side of the second surface of the first substrate 11, wherein a first conductive layer A is embedded in the first insulating layer 12, wherein the first conductive layer A includes at least one transverse conductive layer 13 and at least one longitudinal conductive layer 14, wherein the width of the longitudinal conductive layer 14 in a direction parallel to the first surface is smaller than the width of the transverse conductive layer 13;

[0073] A groove located in the peripheral circuit region II, the groove extending from the first surface into the first substrate 11 and exposing the vertical conductive layer 14;

[0074] A metal barrier layer and a metal layer, wherein the metal barrier layer includes a first metal barrier layer 32a and a second metal barrier layer 32b, wherein the first metal barrier layer 32a covers the sidewalls and the bottom wall of the groove, and the exposed surface of the first conductive layer A, and the second metal barrier layer 32b is formed by etching the first metal barrier layer extending to cover the first surface of the groove periphery; the metal layer includes a first metal layer 33a and a second metal layer 33b, wherein the first metal layer 33a covers the first metal barrier layer surface of the groove and fills the groove, and the second metal layer 33b is formed by etching the first metal layer extending to cover the first metal barrier layer surface of the groove periphery; the first metal layer 33a is electrically connected to the transverse conductive layer 13 through the metal barrier layer 32 between the longitudinal conductive layer 14 and the first metal layer 33a and the longitudinal conductive layer 14;

[0075] A metal grid 30b located in the pixel area I, a metal connection portion 30a located in the peripheral circuit area II and connected to the first metal layer 33a, and a metal shielding layer 30c located between the pixel area I and the peripheral circuit area II, the metal grid 30b, the metal connection portion 30a, and the metal shielding layer 30c all include the second metal barrier layer 32b and the second metal layer 33b stacked in sequence in a direction away from the first surface.

[0076] A shallow trench isolation structure is formed on one side of the first substrate 11 close to the second surface, and the shallow trench isolation structure forms a longitudinal conductive layer 14 having one end electrically connected to at least one of the transverse conductive layers 13. The end of the longitudinal conductive layer 14 not connected to the transverse conductive layer 13, the metal barrier layer 32 between the longitudinal conductive layer 14 and the first metal layer 33a, and the end of the first metal layer 33a close to the longitudinal conductive layer 14 are all located in the shallow trench isolation structure, and the first metal layer 33a is electrically connected to the transverse conductive layer 13 through the metal barrier layer 32 between the longitudinal conductive layer 14 and the first metal layer 33a and the longitudinal conductive layer 14.

[0077] The image sensor also includes: a deep trench isolation structure 15, which extends from the first surface of the first substrate 11 into the first substrate 11; the deep trench isolation structures 15 are arranged in an array form, and the pixels of the image sensor are arranged between the deep trench isolation structures 15, and the projection of the metal grid 30b on the first substrate 11 covers the projection of the deep trench isolation structure 15 on the first substrate 11.

[0078] The image sensor further includes: a second wafer including a second substrate 21, a second insulating layer 22 on the second substrate 21, and a second conductive layer 23 embedded in the second insulating layer 22. The first insulating layer 12 of the first wafer is bonded to the second insulating layer 22 of the second wafer.

[0079] In summary, the present invention provides an image sensor and a manufacturing method thereof, the manufacturing method comprising: providing a first substrate; forming a groove in the peripheral circuit area; forming a metal barrier layer; forming a metal layer; patterning and etching the first metal layer and the first metal barrier layer outside the groove to form a stacked second metal barrier layer and a second metal layer. The metal grid and the metal wiring portion both include the second metal barrier layer and the second metal layer stacked in sequence in a direction away from the first surface. The second metal layer in the metal grid, the second metal layer in the metal wiring portion, and the first metal layer in the groove of the present invention share the same metal layer, reducing the process steps; the second metal barrier layer in the metal grid, the second metal barrier layer in the metal wiring portion, and the first metal barrier layer in the groove also only require one metal barrier layer formation process, reducing the process steps.

[0080] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the method disclosed in the embodiment, since it corresponds to the device disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0081] The above description is only a description of the preferred embodiment of the present invention, and is not any limitation on the scope of rights of the present invention. Any technical personnel in this field can make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications 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 shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for manufacturing an image sensor, characterized in that: include: Providing a first substrate, wherein the first substrate includes a pixel area and a peripheral circuit area; The first substrate has a first surface and a second surface opposite to each other, a first insulating layer is formed on one side of the second surface of the first substrate, and a first conductive layer is embedded in the first insulating layer; forming a groove in the peripheral circuit region, wherein the groove extends from the first surface into the first substrate and exposes the first conductive layer; forming a metal barrier layer, the metal barrier layer comprising a first metal barrier layer covering the sidewalls and the bottom wall of the trench and the exposed surface of the first conductive layer, the first metal barrier layer also extending to cover the first surface outside the trench; forming a metal layer, the metal layer comprising a first metal layer covering a surface of the first metal barrier layer in the groove and filling the groove, the first metal layer also extending to cover a surface of the first metal barrier layer outside the groove; The first metal layer around the groove is patterned and etched using the first metal barrier layer around the groove as an etching stop layer to form a second metal layer on the surface of the first metal barrier layer around the groove; the first metal barrier layer on the first surface around the groove is etched using the second metal layer as a mask to form a second metal barrier layer covering the first surface around the groove; the second metal layer covers the second metal barrier layer to form a metal grid in the pixel area and a metal wiring portion connected to the first metal layer in the peripheral circuit area; the metal grid and the metal wiring portion both include the second metal barrier layer and the second metal layer stacked in sequence in a direction away from the first surface; the metal wiring portion, the first metal layer, the metal barrier layer between the first conductive layer and the first metal layer, and the first conductive layer are electrically connected in sequence to lead the electrical signal of the first conductive layer to the first surface of the substrate.

2. The method for manufacturing an image sensor according to claim 1, wherein: The step of patterning and etching the first metal layer and the first metal barrier layer around the trench comprises: Using a first process, using the first metal barrier layer at the periphery of the trench as an etching stop layer, etching the first metal layer extending and covering the surface of the first metal barrier layer at the periphery of the trench to form a second metal layer on the surface of the first metal barrier layer at the periphery of the trench; A second process is adopted to etch the first metal barrier layer extending to cover the first surface of the periphery of the trench using the second metal layer as a mask to form a second metal barrier layer on the first surface of the periphery of the trench.

3. The method for manufacturing an image sensor according to claim 1, wherein: The first conductive layer comprises a transverse conductive layer and a longitudinal conductive layer, and a width of the longitudinal conductive layer in a direction parallel to the first surface is smaller than a width of the transverse conductive layer; The production method further comprises: A shallow trench is formed on one side of the second surface of the first substrate, the first insulating layer fills the shallow trench to form a shallow trench isolation structure, the shallow trench isolation structure forms the longitudinal conductive layer having one end electrically connected to at least one of the transverse conductive layers, and the end of the longitudinal conductive layer not connected to the transverse conductive layer is located in the shallow trench isolation structure; forming an opening, wherein the opening extends from the first surface and is inserted into the first substrate and communicates with the shallow groove; After forming a protection layer on the sidewall of the opening, the first insulating layer and / or the protection layer between the bottom of the opening and the vertical conductive layer are removed to expose the vertical conductive layer to form the groove.

4. The method for manufacturing an image sensor according to claim 1, wherein: The production method further comprises: forming a deep trench in the pixel region, wherein the deep trench extends from the first surface of the first substrate and is inserted into the interior of the first substrate; A first dielectric layer is formed, wherein the first dielectric layer fills the deep trench to form a deep trench isolation structure, and the first dielectric layer also covers the first surface of the first substrate.

5. The method for manufacturing an image sensor according to claim 4, wherein: The deep trench isolation structures are arranged in an array, the pixel units of the image sensor are arranged between the deep trench isolation structures, and the projection of the metal grid on the first substrate covers the projection of the deep trench isolation structure on the first substrate.

6. The method for manufacturing an image sensor according to claim 1, wherein: The metal barrier layer is titanium nitride, and the metal layer is tungsten.

7. An image sensor, comprising: A first substrate, wherein the first substrate includes a pixel area and a peripheral circuit area; The first substrate has a first surface and a second surface opposite to each other, a first insulating layer is formed on one side of the second surface of the first substrate, and a first conductive layer is embedded in the first insulating layer; A groove located in the peripheral circuit area, the groove extending from the first surface into the first substrate and exposing the first conductive layer; A metal barrier layer and a metal layer, the metal barrier layer comprising a first metal barrier layer and a second metal barrier layer, the first metal barrier layer covering the sidewalls and bottom wall of the groove, and the exposed surface of the first conductive layer, the second metal barrier layer being formed by patterning and etching the first metal barrier layer extending to cover the first surface of the periphery of the groove; the metal layer comprising a first metal layer and a second metal layer, the first metal layer covering the surface of the first metal barrier layer in the groove and filling the groove, the second metal layer being formed by patterning and etching the first metal layer extending to cover the surface of the first metal barrier layer of the periphery of the groove; A metal grid located in the pixel area and a metal connection portion located in the peripheral circuit area and connected to the first metal layer. The metal grid and the metal connection portion both include the second metal barrier layer and the second metal layer stacked in sequence in a direction away from the first surface. The metal connection portion, the first metal layer, the metal barrier layer between the first conductive layer and the first metal layer, and the first conductive layer are electrically connected in sequence to lead the electrical signal of the first conductive layer to the first surface of the substrate.

8. The image sensor according to claim 7, wherein: The first conductive layer comprises a transverse conductive layer and a longitudinal conductive layer, and a width of the longitudinal conductive layer in a direction parallel to the first surface is smaller than a width of the transverse conductive layer; A shallow trench isolation structure is formed on one side of the second surface of the first substrate, and the shallow trench isolation structure forms the longitudinal conductive layer having one end electrically connected to at least one of the transverse conductive layers, the end of the longitudinal conductive layer not connected to the transverse conductive layer, the metal barrier layer between the longitudinal conductive layer and the first metal layer, and the end of the first metal layer close to the longitudinal conductive layer are all located in the shallow trench isolation structure, and the first metal layer is electrically connected to the transverse conductive layer through the metal barrier layer between the longitudinal conductive layer and the first metal layer and the longitudinal conductive layer.

9. The image sensor according to claim 7, wherein: The image sensor further comprises: A deep trench isolation structure is located in the pixel area, wherein the deep trench isolation structure extends from the first surface of the first substrate and is inserted into the interior of the first substrate; the deep trench isolation structures are arranged in an array, the pixel units of the image sensor are arranged between the deep trench isolation structures, and the projection of the metal grid on the first substrate covers the projection of the deep trench isolation structure on the first substrate.

10. The image sensor according to claim 7, wherein: The image sensor further comprises: A second substrate, a second insulating layer located on the second substrate, and a second conductive layer embedded in the second insulating layer; The first insulating layer and the second insulating layer are bonded together.

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