Backside illuminated image sensor and manufacturing method thereof

Abstract

The present invention relates to a backside illuminated image sensor and a method for manufacturing the same, and more particularly, to a backside illuminated image sensor in which an upper conductive film is formed in a separated space of a substrate but not on the backside of the substrate, according to the back-illuminated image sensor and the manufacturing method thereof, the thickness of a structure body formed on the back surface of a substrate can be relatively thinned in a pad region, so that strip-shaped stripes are prevented from being formed on the substrate, and corners of an upper conductive film can be prevented from being damaged in advance.

Description

Technical Field

[0001] This invention relates to a back-illuminated image sensor and its manufacturing method, and more particularly to a back-illuminated image sensor and its manufacturing method thereof, which forms an upper conductive film in the space between substrates but not on the back side of the substrate, thereby making the thickness of the structure formed on the back side of the substrate relatively thinner in the pad area and thus preventing the formation of strip-like stripes on the substrate in advance, and also preventing damage to the corners of the upper conductive film in advance. Background Technology

[0002] An image sensor is an image capturing element used in devices such as mobile phone cameras to generate images. Based on their manufacturing process and application, they can be divided into charge-coupled device (CCD) image sensors and complementary metal-oxide-semiconductor (CMOS) image sensors. Among these, CMOS image sensors are widely used in general semiconductor chip manufacturing processes due to their superior integration competitiveness, cost-effectiveness, and ease of connection with peripheral chips.

[0003] In existing front-illuminated complementary metal-oxide-semiconductor (CMOS) image sensors, wiring portions can be formed sequentially on the front side of a silicon wafer. However, image sensors with the above-described structure suffer from a reduction in the amount of incident light reaching the light-receiving element due to the metal wiring within the wiring portions. In response, a so-called back-illuminated complementary metal-oxide-semiconductor (CMOS) image sensor (BIS) has been developed, in which wiring portions are arranged on the front side of a substrate, and light is incident on the back side of the substrate.

[0004] Figure 1 It is a cross-sectional view used to illustrate the structure of an existing back-illuminated image sensor; Figure 2 It is used for in Figure 1 The reference diagram illustrates the problems that occur during spin coating processes using a back-illuminated image sensor structure. Figure 3 It is used for in Figure 1 The diagram shows a cross-sectional view illustrating damage to the corner of the conductive film in a back-illuminated image sensor structure.

[0005] In the following sections, the structure of existing back-illuminated image sensors and the problems arising therefrom will be described in detail with reference to the accompanying drawings.

[0006] See Figure 1 In a conventional back-illuminated image sensor 9, a lower insulating film 920 can be formed on the front side 911 of a substrate 910 having a front side 911 and a back side 913 within the pad region A3. Furthermore, an adhesive layer 940 can be formed on a metal layer 921a formed within the spacer space A31 of the substrate 910, and a conductive film 950 can be formed on the adhesive layer 940. Additionally, an insulating film 930 can be formed between the adhesive layer 940 and the substrate 910. At this time, the conductive film 950 can extend from the adhesive layer 940 within the spacer space A31 of the substrate 910 to the sidewall of the substrate 910 and the back side 913 of the substrate 910. That is, the conductive film 950 can be formed on the adhesive layer 940 on the back side 913 of the substrate 910. Therefore, because of the insulating film 930, adhesive layer 940, and conductive film 950 formed on the back side 913 of the substrate 910 within the pad region A3, an integral structure B (see reference) is formed on the back side 913. Figure 2 The thickness B1 of the ) will inevitably be relatively thick.

[0007] See Figure 2 Typically, during the formation of the color filter and / or microlens of the back-illuminated image sensor 9, a spin-coating process is performed on the photosensitive liquid. During this process, the photosensitive liquid cannot be uniformly coated due to the structure formed on the back side 913 of the substrate 910, and it tends to accumulate on the side adjacent to the structure, resulting in striped streaks (ST) on the substrate 910. This can potentially cause defects in the appearance and color deviation of the image sensor 9.

[0008] In addition, see Figure 3 When forming a photoresist film PR on the conductive film 950 on the back side 913 of the substrate 910 to complete the conductive film 950, because the corner region of the photoresist film PR is relatively thin, loss will inevitably occur on the conductive film 950 directly below the photoresist film PR. That is, it may cause the corner side of the conductive film 950 to be etched. Therefore, it may cause damage to the corner of the completed conductive film 950.

[0009] To address the problems described above, the inventors of this invention propose a star-shaped back-illuminated image sensor and a method for manufacturing the same, which will be described in detail below.

[0010] Prior technology documents

[0011] Patent documents

[0012] US Patent 9,054,106 B2, "Semiconductor Structure and Method for Manufacturing the Same" Summary of the Invention

[0013] The present invention aims to solve the problems existing in the prior art as described above.

[0014] The purpose of this invention is to provide a back-illuminated image sensor and its manufacturing method, which can reduce the thickness of the entire structure formed on the back side of the substrate by not forming an upper conductive film on the back side of the substrate, thereby preventing the formation of stripes due to the accumulation of photosensitive liquid during spin coating.

[0015] Furthermore, the present invention aims to provide a back-illuminated image sensor and a method thereof for manufacturing the same, which can prevent damage to the corner portions of the upper conductive film during its formation by not forming an upper conductive film on the back side of the substrate.

[0016] Furthermore, the present invention aims to provide a back-illuminated image sensor and a method thereof for manufacturing the same, by having one end of the lower conductive film located inside a recess on the back side of the substrate, thereby further reducing the thickness of the integral structure formed on the back side of the substrate.

[0017] To achieve the objectives described above, the present invention can be implemented through embodiments configured as follows.

[0018] In one embodiment of the present invention, the back-illuminated image sensor according to the present invention is characterized by comprising: substrates spaced apart from each other; a lower insulating film located on the front side of the substrates; metal layers stacked within the lower insulating film and connected to each other by contact plugs; an insulating film extending along the sidewalls and back side of the substrates within the spaced space of the substrates; a lower conductive film connected to the metal layers within the spaced space of the substrates and extending along the inner sidewalls of the insulating film; and an upper conductive film located restrictively within the spaced space of the substrates on the lower conductive film.

[0019] In another embodiment of the present invention, the back-illuminated image sensor according to the present invention is characterized in that the upper conductive film comprises: a first portion located on the lower conductive film directly above the metal layer; and a second portion extending along the inner sidewall of the lower conductive film on the sidewall of the substrate.

[0020] In another embodiment of the invention, the back-illuminated image sensor according to the invention is characterized in that the second portion has a spacer cross-sectional shape.

[0021] In another embodiment of the invention, the back-illuminated image sensor according to the invention is characterized in that the upper end of the inner sidewall of the second portion has a substantially curved cross-sectional shape.

[0022] In another embodiment of the present invention, the back-illuminated image sensor according to the present invention is characterized in that the side end of the first portion is spaced apart from the lower side of the adjacent second portion.

[0023] In another embodiment of the present invention, the back-illuminated image sensor according to the present invention is characterized in that the first part and the second part are physically connected.

[0024] In another embodiment of the present invention, the back-illuminated image sensor according to the present invention is characterized in that the upper conductive film further includes a connecting portion that connects the first portion and the second portion to each other, wherein the upper side of the connecting portion is located at a lower position than the upper side of the first portion.

[0025] In another embodiment of the present invention, the back-illuminated image sensor according to the present invention is characterized in that the upper conductive film further includes a connecting portion that connects the first portion and the second portion to each other, wherein the upper side of the connecting portion is located at substantially the same height as the upper side of the first portion, or at a position higher than the upper side of the first portion.

[0026] In another embodiment of the present invention, the back-illuminated image sensor according to the present invention is characterized in that the back surface of the substrate includes: a recess located on a side adjacent to the substrate by a space; and a protrusion located at a relatively higher position than the recess by a step portion on the boundary side of the recess, the insulating film being located on the recess and the protrusion, and the side end of the lower conductive film being located on the recess.

[0027] In another embodiment of the present invention, the back-illuminated image sensor according to the present invention is characterized in that the upper side surface of the lower conductive film on the recess is at substantially the same height as or at a relatively lower height than the upper side surface of the insulating film on the protrusion.

[0028] In another embodiment of the present invention, the back-illuminated image sensor according to the present invention includes: a pixel region that absorbs incident light; a shielding region surrounding the pixel region as a light shielding region; and a pad region located on one side of the outer contour of the shielding region, the pad region including: substrates spaced apart from each other; a wiring region including a metal layer located on the front side of the substrate; an insulating film located on the sidewall and back side of the substrate; a lower conductive film located on the inner sidewall of the insulating film; and an upper conductive film located on the lower conductive film, the upper conductive film including: a first portion located on the lower conductive film directly above the metal layer; and a second portion extending along the inner sidewall of the lower conductive film on the sidewall of the substrate.

[0029] In another embodiment of the invention, the back-illuminated image sensor according to the invention is characterized by further comprising solder balls located on the first portion.

[0030] In another embodiment of the invention, the back-illuminated image sensor according to the invention is characterized in that the upper end of the inner sidewall of the second portion has a substantially curved cross-sectional shape.

[0031] In another embodiment of the present invention, the back-illuminated image sensor according to the present invention is characterized in that the second portion is spaced apart from the adjacent first portion.

[0032] In another embodiment of the present invention, the back-illuminated image sensor according to the present invention is characterized in that the upper conductive film further includes a connecting portion that connects the first portion and the second portion to each other.

[0033] In another embodiment of the present invention, the method for manufacturing a back-illuminated image sensor according to the present invention is characterized by comprising: a step of forming a spacer space between the substrates by etching a substrate and a lower insulating film on the front side of the substrate; a step of forming an insulating film extending along the sidewall and back side of the substrate within the spacer space of the substrate; a step of forming a lower conductive film connected to a metal layer in the lower insulating film and extending along the inner sidewall of the insulating film within the spacer space of the substrate; and a step of forming an upper conductive film on the lower conductive film within the spacer space of the substrate, the upper conductive film comprising: a first portion located on the lower conductive film directly above the metal layer; and a second portion extending along the inner sidewall of the lower conductive film on the sidewall of the substrate, having a spacer cross-sectional shape.

[0034] In another embodiment of the present invention, the method for manufacturing a back-illuminated image sensor according to the present invention is characterized in that the lower conductive film and the upper conductive film are formed by the following steps: forming a first conductive film on the metal layer and the insulating film; forming a second conductive film on the first conductive film; completing the upper conductive film by performing an etching process after forming a first photoresist film on the second conductive film; and completing the lower conductive film by performing an etching process after forming a second photoresist film in the space between the first conductive film and the substrate.

[0035] In another embodiment of the present invention, the method for manufacturing a back-illuminated image sensor according to the present invention is characterized in that the distance between the side end of the first photoresist film and the sidewall of the adjacent substrate is in the range of 0.9 μm to 2.0 μm.

[0036] In another embodiment of the present invention, the method for manufacturing a back-illuminated image sensor according to the present invention is characterized in that the step of completing the upper conductive film includes the step of removing all the second conductive films located on the back side of the substrate.

[0037] In another embodiment of the present invention, the method for manufacturing a back-illuminated image sensor according to the present invention is characterized in that one side of the lower conductive film is located on the back side of the substrate.

[0038] The present invention can achieve the effects described below through the process described above.

[0039] By not forming an upper conductive film on the back side of the substrate, the present invention can reduce the thickness of the entire structure formed on the back side of the substrate, thereby preventing the formation of stripes due to the accumulation of photosensitive liquid during spin coating.

[0040] Furthermore, by not forming the upper conductive film on the back side of the substrate, the present invention can prevent damage to the corners of the upper conductive film during its formation.

[0041] Furthermore, by positioning one end of the lower conductive film within a recess on the back side of the substrate, the present invention can further reduce the thickness of the overall structure formed on the back side of the substrate.

[0042] Furthermore, it should be noted in advance that even effects not explicitly mentioned herein, effects and potential effects achieved through the technical features of the present invention as described in the following description are considered to be described in the description of the present invention. Attached Figure Description

[0043] Figure 1This is a cross-sectional view used to illustrate the structure of an existing back-illuminated image sensor.

[0044] Figure 2 It is used for in Figure 1 The reference diagram illustrates the problems that occur when performing a spin coating process under the back-illuminated image sensor structure shown in the figure.

[0045] Figure 3 It is used for in Figure 1 The diagram shows a cross-sectional view illustrating damage to the corner of the conductive film in a back-illuminated image sensor structure.

[0046] Figure 4 This is a plan view related to a back-illuminated image sensor according to one embodiment of the present invention.

[0047] Figure 5 This is a cross-sectional view of AA' according to the first embodiment of the present invention.

[0048] Figure 6 This is a cross-sectional view of AA' according to the second embodiment of the present invention.

[0049] Figure 7 This is a cross-sectional view of AA' according to the third embodiment of the present invention.

[0050] Figure 8 This is a cross-sectional view of AA' according to the fourth embodiment of the present invention.

[0051] Figures 9 to 16 This is a cross-sectional view used to illustrate a method for manufacturing a back-illuminated image sensor according to an embodiment of the present invention.

[0052] Symbol Explanation

[0053] 1: Back-illuminated image sensor according to the first embodiment, 110: substrate, 111: front side, 113: back side, 115: sidewall, 120: wiring area, 121: metal layer, 121a: first metal layer, 121b: second metal layer, 123: contact plug, 125: lower insulating film, 130: insulating film, 140: lower conductive film, 150: upper conductive film, 151: first portion, 153: second portion, 160: solder ball, 2: Back-illuminated image sensor according to the second embodiment, 25 5: Connecting portion; 3: Back-illuminated image sensor according to the third embodiment; 4: Back-illuminated image sensor according to the fourth embodiment; 413a: Step portion; 413b: Recessed portion; 413c: Protruding portion; A1: Pixel area; A2: Shielding area; A3: Pad area; A31: Spacing space; PR1, PR2, PR3, PR4: Photoresist film; I: Insulating film layer; C1: First conductive film; C2: Second conductive film; D1: Spacing distance between the side end of the photoresist film and the sidewall of the adjacent substrate. Detailed Implementation

[0054] The embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. The embodiments of the present invention can be modified in various ways and should not be construed as limiting the scope of the invention to the following embodiments, but should be interpreted based on the matters set forth in the claims. Furthermore, these embodiments are provided for reference only to provide a more complete introduction to the invention to those skilled in the art.

[0055] Unless explicitly stated in the context, the singular form used in this specification may also include the plural form. Furthermore, the terms "comprise" and / or "comprising" as used in this specification indicate only the presence of the mentioned shapes, numbers, steps, actions, components, elements, and / or combinations thereof, and do not exclude the possibility of the presence or addition of more than one other shape, number, action, component, element, and / or combination thereof.

[0056] It should be noted that when described below as a component (or layer) disposed on other component (or layer), a component can be directly disposed on other component, or other component or layer may exist between the corresponding component. Furthermore, when described as a component directly disposed on or above other component, no other component will exist between the corresponding component. Additionally, the terms "above," "upper part," "lower part," "upper side," "lower side," "one side," or "side" of a component refer to relative positional relationships.

[0057] Furthermore, in cases where an embodiment can be implemented in different ways, individual functions may be executed in a different order than that described in the specification. For example, two consecutive projects may be executed substantially simultaneously, or they may be executed in the reverse order described in the specification.

[0058] Figure 4 This is a plan view related to a back-illuminated image sensor according to one embodiment of the present invention, and Figure 5 This is a cross-sectional view of AA' according to the first embodiment of the present invention.

[0059] In the following description, a back-illuminated image sensor 1 according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0060] See Figure 4 as well as Figure 5 The present invention relates to a back-illuminated image sensor 1, and more particularly to a back-illuminated image sensor 1 that, by forming an upper conductive film 150 in a space A31 between substrates 110 but not on the back side of the substrate, can make the overall thickness of the structure formed on the back side 113 of the substrate 110 relatively thinner in the pad area A3, thereby preventing the formation of streaks on the substrate 110 in advance, and can also prevent damage to the corner portion C of the upper conductive film 150 in advance.

[0061] See Figure 4 According to one embodiment of the present invention, a back-illuminated image sensor 1 may include: a pixel region A1; a shield region A2 surrounding the pixel region A1; and a pad region A3 located on one side of the outer contour of the shield region A2. The pixel region A1 is a region that absorbs light incident from the outside, the shield region A2 is a light-shielding region, and the pad region A3 is a region where contact pads are formed. Furthermore, within the pad region A3, a space A31 without the presence of the substrates 110 can be formed between a pair of substrates 110 by etching the substrates 110.

[0062] The following content will refer to Figure 5The structure of the back-illuminated image sensor 1 inside the pad region A3 will be described in detail. First, a substrate 110 can be formed on the back-illuminated image sensor 1. The substrate 110 is a silicon (Ai) substrate, and may include, for example, an epitaxial substrate or a bulk substrate. As described above, the substrate 110 can be etched at specific locations within the pad region A3, thereby forming a spacer space A31 between a pair of substrates 110. That is, it can have a configuration in which substrates 110 are arranged on the left and right sides with reference to the spacer space A31. Furthermore, the substrate 110 may have a sidewall 115 on the front side 111, the back side 113, and one side of the boundary of the spacer space A31.

[0063] Furthermore, a wiring region 120 may be formed on the front side 111 of the substrate 110. The wiring region 120 may include a metal layer 121, a contact plug 123, and a lower insulating film 125.

[0064] For example, the metal layer 121 may be composed of a single metal or an alloy film containing different metals, such as preferably an aluminum (Al) film, but the scope of the invention is not limited thereto. Furthermore, the metal layer 121 may have a multi-layered structure within the lower insulating film 125. For example, a first metal layer 121a may be formed on the side closest to the back surface 113 of the substrate 110, and a second metal layer 121b may be formed below the first metal layer 121a, but the total number of metal layers is not particularly limited.

[0065] Furthermore, individual metal layers 121 can be electrically connected to adjacent metal layers 121 by means of contact plugs 123. Contact plugs 123 can be formed, for example, within the lower insulating film 1255 by a metal inlay (Damascene) process, and in order to be electrically connected to the metal layers 121, they can be formed using one or more selected from polycrystalline silicon films doped with conductive substances, i.e., impurity ions, metals, or alloy films composed of different metals.

[0066] Furthermore, the lower insulating film 125 can be formed, for example, using an oxide film selected from borosilicate glass (BPSG), phosphosilicate glass (PSG), borosilicate glass (BSG), undoped silicate glass (USG), tetraethoxysilane (TEOS), or high-density polyethylene (HDP) films, or can be composed of a laminated film consisting of two or more layers of the aforementioned materials. Next, after depositing the lower insulating film 125, planarization can be performed, for example, by a chemical mechanical polishing (CMP) process.

[0067] An insulating film 130 may be formed within the space A31 of the substrate 110. For example, the insulating film 130 may be formed extending along the sidewall 115 and back surface 113 of the substrate 110. In some cases, the insulating film 130 may also be formed extending at a distance on the first metal layer 121a. The insulating film 130 may, for example, comprise a silicon oxide film, a silicon nitride film, or a silicon oxynitride film, but the scope of the invention is not limited by the examples described.

[0068] Furthermore, a lower conductive film 140 may be formed on the insulating film 130. The lower conductive film 140 may be, for example, a film containing tungsten (W), and may be physically connected to the first metal layer 121a. As an example, the lower conductive film 140 may be formed on the first metal layer 121a, and may also be formed on the inner sidewall of the insulating film 130 formed along the sidewall 115 of the substrate 110. Furthermore, the lower conductive film 140 may or may not be formed on the insulating film 130 on the back surface 113 of the substrate 110. It is preferable that the lower conductive film 140 is formed in a continuous manner. Furthermore, when the lower conductive film 140 extends on the back surface 113 of the substrate 110 to the shielding region A2, the lower conductive film 140 may also function as a shielding layer for shielding light.

[0069] Furthermore, an upper conductive film 150 may be formed on the lower conductive film 140. The upper conductive film 150 is preferably formed within the spacer space A31 of the substrate 110, but not on the back surface 113 of the substrate 110. That is, the upper conductive film 150 is formed only within the spacer space A31 of the substrate 110. The upper conductive film 150 may, for example, be a single metal or an alloy film of different metals comprising titanium (Ti), titanium nitride (TiN), and aluminum (Al), but the scope of the invention is not limited by the examples described. Specifically, the upper conductive film 510 may have a first portion 151 and a second portion 153.

[0070] The first portion 151 can be formed on the upper side surface of the lower conductive film 140, which is formed directly above the first metal layer 121a. In this case, the upper side surface of the first portion 151 can be substantially flat, or it can have a step on one side. Furthermore, the second portion 153 is formed on the sidewall of the upper conductive film 150, which is formed within the space A31 along the inner sidewall of the lower conductive film 140 on the sidewall 115 of the substrate 110. In this case, the second portion 153 can have a spacer-like cross-sectional shape. That is, the upper end of the inner sidewall of the second portion 153 can substantially have a curved cross-sectional shape. Furthermore, the second portion 153 can be formed on the opposing sidewalls 115 of the substrate 110.

[0071] Next, we will describe in detail the various cross-sectional shapes of the upper conductive film 150.

[0072] In the first embodiment, the first portion 151 and the second portion 153 of the upper conductive film 510 can be spaced apart from each other by a certain distance. That is, the side end of the first portion 151 and the lower side of the second portion 153 can be physically separated from each other without being connected. In this case, taking the first portion 151 as a reference, among the pair of left and right second portions 153, only one side of the second portion 153 can be separated from the first portion 151 while the other second portion 153 is connected to the first portion 151.

[0073] Figure 6 This is a cross-sectional view of AA' according to the second embodiment of the present invention.

[0074] Next, please refer to Figure 6 The back-illuminated image sensor 2 according to the second embodiment will be described. The first portion 251 and the second portion 23 of the upper conductive film 250 can be connected without being separated. That is, the first portion 251 and the second portion 253 do not have a side that is separated from each other. In the following description, the side where the first portion 251 and the second portion 253 are connected is referred to as the "connection portion 255". The upper side surface of the connection portion 255 can be located below the upper side surface of the first portion 21. Therefore, by means of the connection portion 255, the upper conductive film 250 can have a cross-sectional shape that is recessed downward between the first portion 251 and the second portion 253.

[0075] Figure 7 This is a cross-sectional view of AA' according to the third embodiment of the present invention.

[0076] Next, please refer to Figure 7 The back-illuminated image sensor 3 according to the third embodiment will be described. The upper side of the connection portion 355 between the first portion 351 and the second portion 353 may be formed at substantially the same height as the upper side of the adjacent first portion 351, or at a position higher than the upper side of the first portion 351.

[0077] According to the first to third embodiments, the cross-sectional shape of the upper conductive film can be controlled by adjusting the distance between the mask pattern used to form the upper conductive film and the sidewall 115 of the substrate 10. The details related thereto will be explained in the subsequent "Manufacturing Method of Back-illuminated Image Sensor".

[0078] See Figure 5Within the space A31 between the pad regions A3, solder balls 160 can be formed on the upper conductive film 150. The solder balls 160 may, for example, comprise gold (Au) or nickel (Ni), but the scope of the invention is not limited by the examples described.

[0079] In the following description, the structure and problems of the existing back-illuminated image sensor 9 in the pad area A3 will be explained with reference to the accompanying drawings.

[0080] As mentioned above, see Figure 1 In the existing back-illuminated image sensor 9, a lower insulating film 920 can be formed on the front side 911 of the substrate 910 within the pad region A3. Furthermore, an adhesive layer 940 can be formed on a metal layer 921a formed within the spacer space A31 of the substrate 910, and a conductive film 950 can be formed on the adhesive layer 940. Additionally, an insulating film 930 can be formed between the adhesive layer 940 and the substrate 910. In this case, the conductive film 950 can extend from the adhesive layer 940 within the spacer space A31 of the substrate 910 to the inner sidewall 915 of the substrate 910 and the back side 913 of the substrate 910. That is, the conductive film 950 can be formed on the adhesive layer 940 on the back side 913 of the substrate 910. Therefore, because the insulating film 930, adhesive layer 940, and conductive film 950 are formed on the back side 913 of the substrate 910 within the pad region A3, the thickness B of the overall structure formed on the back side 913 will inevitably be relatively thick.

[0081] See Figure 2 Typically, during the formation of the color filter and / or microlens of the back-illuminated image sensor 9, a spin-coating process is performed on the photosensitive liquid. During this process, the photosensitive liquid cannot be uniformly coated due to the structure formed on the back side 913 of the substrate 910, and it tends to accumulate on the side adjacent to the structure, resulting in striped streaks (ST) on the substrate 910. This can potentially cause defects in the appearance and color deviation of the image sensor 9.

[0082] In addition, see Figure 3 When forming a photoresist film PR on the conductive film 950 on the back side 913 of the substrate 910 to complete the conductive film 950, because the corner region of the photoresist film PR is relatively thin, loss will inevitably occur on the conductive film 950 directly below the photoresist film PR. Therefore, the corner of the completed conductive film 950 may be damaged.

[0083] See Figure 5To address the problems described above, the back-illuminated image sensor 1 according to one embodiment of the present invention is characterized in that the upper conductive film 150 is formed only within the space A31, but not on the back surface 113 of the substrate 110. Therefore, by reducing the overall height of the structures (insulating film 130, lower conductive film 140, and upper conductive film 150) on the back surface 113 of the substrate 110, the possibility of forming stripes during spin coating can be relatively suppressed, and the possibility of damage to the corner portions of the upper conductive film 150 can also be relatively suppressed.

[0084] Figure 8 This is a cross-sectional view of AA' according to the fourth embodiment of the present invention.

[0085] In the following description, a back-illuminated image sensor 4 according to a fourth embodiment of the present invention will be described in detail. During the description of the back-illuminated image sensor 4 according to the fourth embodiment, only the structural differences between it and the back-illuminated image sensor 1 according to the first embodiment will be explained in detail.

[0086] See Figure 8 In the back-illuminated image sensor 4 according to the fourth embodiment of the present invention, the back surface 413 of the substrate 410 has a step portion 413a. That is, the back surface 413 of the substrate 410 can be formed such that its height increases by means of the step portion 413a as it extends outward from the side adjacent to the space A31. In the following description, the area with a relatively lower height in the back surface 413 of the substrate 410 is referred to as the recessed portion 413b, and the area with a relatively higher height is referred to as the protruding portion 413c.

[0087] An insulating film 430 is formed on the back surface 413 of the substrate 410, and a lower conductive film 40 can extend from the sidewall 415 of the substrate 410 to the recess 413b of the substrate 410 within the space A31 of the substrate 410. In this case, it is preferable that the upper side surface of the lower conductive film 440 on the back surface 413 of the substrate 410 is at substantially the same height as the upper side surface of the insulating film 430 on the protrusion 413c, or at a relatively lower height. As described above, by further reducing the height of the structure on the back surface 413 of the substrate 410, the possibility of the problems described above occurring can be further suppressed.

[0088] In addition, Figure 8 In this embodiment, the first part 451 and the second part 453 are formed apart from each other, but as shown in the second embodiment and the third embodiment, the first part 451 and the second part 453 can also be connected to each other.

[0089] Figures 9 to 16This is a cross-sectional view used to illustrate a method for manufacturing a back-illuminated image sensor according to an embodiment of the present invention.

[0090] In the following description, a method for manufacturing a back-illuminated image sensor according to a first embodiment of the present invention will be described in detail with reference to the accompanying drawings. The process following the formation of the wiring region 120 on the back surface 111 of the substrate 110 will be described in detail.

[0091] See Figure 9 First, a thinning process is performed on the substrate 110. The thinning process is a process of polishing the back side 113 of the substrate 110, for example, by chemical mechanical polishing (CMP).

[0092] See Figure 10 Next, the spacer space A31 of the substrate 110 is formed by etching the substrate 110 and the lower insulating film 125, exposing the upper side of the first metal layer 121a. This process can be performed by forming a photoresist film PR1 on the back side 113 of the substrate 110 and then performing the etching process. After the etching process is completed, the photoresist film PR1 is removed. Next, in order to form a step on the back side 413 of the substrate 410 as described in the fourth embodiment, an additional etching process can be performed on one side of the back side 413 of the substrate 410.

[0093] Next, the formation process of the insulating film 130 will be described below. (See attached text.) Figure 11 First, an insulating film layer I is formed on the first metal layer 121a, the sidewall 115 of the substrate 110, and the back surface 113 of the substrate 110. (See reference...) Figure 12 After forming a photoresist film PR2 on the insulating film layer I, an etching process can be performed on the insulating film layer I to complete the insulating film 130. After completing the insulating film 130, at least one upper side of the first metal layer 121a can be exposed. After completing the insulating film 130, the photoresist film PR2 is removed. As an example of the etching process for the insulating film layer I, an anisotropic etching process can be used.

[0094] Next, the lower conductive film 140 and the upper conductive film 150 are formed. The formation process of the lower conductive film 140 and the upper conductive film 150 will be described below. (See reference...) Figure 13 First, a first conductive film C1, such as tungsten (W), is formed on the upper surface of the first metal layer 121a and the insulating film 130. Then, a second conductive film C2, such as aluminum (Al), is formed on the first conductive film C1. (See reference...) Figure 14Next, after forming a photoresist film PR3 on the second conductive film C2, an etching process is performed to complete the upper conductive film 150. Then, the photoresist film PR3 is removed. The etching process for the second conductive film C2 can be, for example, an anisotropic etching process.

[0095] At this point, it is preferable that the side end of the photoresist film PR3 is spaced a certain distance D1 from the sidewall 115 of the adjacent substrate 110. For example, it is preferable that the side end of the photoresist film PR3 is spaced between approximately 0.9 μm and 2.0 μm from the sidewall 115 of the adjacent substrate 110. If the side end of the photoresist film PR3 is spaced less than approximately 0.9 μm from the sidewall 115 of the adjacent substrate 110, the upper conductive film 150 may have one side formed on the back surface 113 of the substrate 110, or may be formed at a position higher than the back surface 113 of the substrate 110. Furthermore, if the side end of the photoresist film PR3 is spaced more than approximately 2.0 μm from the sidewall 115 of the adjacent substrate 110, it will lead to an increase in chip size.

[0096] When the distance between the side end of the photoresist film PR3 and the sidewall 11 of the adjacent substrate 110 is in the range of approximately 0.9 μm to 2.0 μm, as the distance between the side end of the photoresist film PR3 and the sidewall 115 of the adjacent substrate 110 increases, as described in the first embodiment, the first portion 151 and the second portion 153 may be spaced apart from each other, or as described in the second embodiment, the connecting portion 255 may have a downwardly recessed cross-sectional shape. Furthermore, when the distance between the side end of the photoresist film PR3 and the sidewall 115 of the adjacent substrate 110 decreases, as described in the third embodiment, the upper side surface of the connecting portion 355 may be formed at substantially the same height as the upper side surface of the adjacent first portion 351, or at a position higher than the upper side surface of the first portion 351.

[0097] See Figure 15 After the upper conductive film 150 is completed, the lower conductive film 140 can be completed by etching the first conductive film C1 after forming a photoresist film PR4 on the first conductive film C1 and the spacer A31. After forming the lower conductive film 140, the photoresist film PR4 is removed. Furthermore, as an example of the etching process for the first conductive film C1, an anisotropic etching process can be used. In this process, the first conductive film C1 on the back surface 113 of the substrate 110 can be removed, or at least a portion can remain.

[0098] See Figure 16 Next, solder balls 160 are formed on the upper conductive film 150 within the space A31.

[0099] The detailed description above is an illustration of the present invention. Furthermore, the above description is merely a description of preferred embodiments of the invention, and the invention can be used in many different combinations, modifications, and environments. That is, changes or modifications can be made within the scope of the inventive concept disclosed in this specification, the equivalent scope of the described disclosure, and / or the scope of technology or knowledge in the industry. The embodiments described above are merely illustrative of the best state for implementing the technical idea of ​​the invention, and various modifications can be made according to the specific application field and usage requirements of the invention. Therefore, the detailed description of the invention above is not intended to limit the invention to the disclosed embodiments.

Claims

1. A back-illuminated image sensor, characterized in that, include: Separated substrates; The lower insulating film is located on the front side of the substrate; Metal layers, which are stacked within the lower insulating film and connected to each other via contact plugs; An insulating film that extends along the sidewalls and back surface of the substrate within the spaced space between the substrates. A lower conductive film, which is connected to the metal layer within the spaced space of the substrate and extends along the inner sidewall of the insulating film; and An upper conductive film is confined within the space between the substrates on the lower conductive film.

2. The back-illuminated image sensor according to claim 1, characterized in that, The upper conductive film includes: The first part is located on the lower conductive film directly above the metal layer; and The second part extends along the inner sidewall of the lower conductive film on the sidewall of the substrate.

3. The back-illuminated image sensor according to claim 2, characterized in that, The second part has a spacer-like cross-sectional shape.

4. The back-illuminated image sensor according to claim 2, characterized in that, The upper end of the inner wall of the second part has a substantially curved cross-sectional shape.

5. The back-illuminated image sensor according to claim 2, characterized in that, The side end of the first part is separated from the lower side of the adjacent second part.

6. The back-illuminated image sensor according to claim 2, characterized in that, The first part and the second part are physically connected.

7. The back-illuminated image sensor according to claim 6, characterized in that, The upper conductive film also includes a connecting portion that connects the first portion and the second portion to each other. The upper side of the connecting part is located at a lower position compared to the upper side of the first part.

8. The back-illuminated image sensor according to claim 6, characterized in that, The upper conductive film also includes: The connecting part connects the first part and the second part to each other. The upper side of the connecting portion is at substantially the same height as the upper side of the first portion, or at a position higher than the upper side of the first portion.

9. The back-illuminated image sensor according to claim 1, characterized in that, The back side of the substrate includes: A recessed portion, located on a side adjacent to the substrate by a space; and The protrusion is located at a relatively higher position compared to the recess, by means of a step portion on the boundary side with the recess. The insulating film is located on the recessed portion and the protruding portion. The side end of the lower conductive film is located on the recess.

10. The back-illuminated image sensor according to claim 9, characterized in that, The upper side of the lower conductive film on the recess is at substantially the same height as or at a relatively lower height than the upper side of the insulating film on the protrusion.

11. A back-illuminated image sensor, characterized in that, include: A pixel region that absorbs incident light; A shielding region, which surrounds the pixel region, serves as a light-shielding region; as well as The pad area is located on one side of the outer contour of the shielding area. The pad area includes: Separated substrates; The wiring area, which includes a metal layer, is located on the front side of the substrate; An insulating film is located on the sidewalls and back surface of the substrate; The lower conductive film is located on the inner wall of the insulating film; and The upper conductive film is located on top of the lower conductive film. The upper conductive film includes: The first part is located on the lower conductive film directly above the metal layer; and The second part extends along the inner sidewall of the lower conductive film on the sidewall of the substrate.

12. The back-illuminated image sensor according to claim 11, characterized in that, It also includes solder balls, which are located on the first part.

13. The back-illuminated image sensor according to claim 11, characterized in that, The upper end of the inner wall of the second part has a substantially curved cross-sectional shape.

14. The back-illuminated image sensor according to claim 11, characterized in that, The second part is separated from the adjacent first part.

15. The back-illuminated image sensor according to claim 11, characterized in that, The upper conductive film also includes a connecting portion that connects the first portion and the second portion to each other.

16. A method for manufacturing a back-illuminated image sensor, characterized in that, include: The step of forming a spaced space between the substrates by etching the substrate and the lower insulating film on the front side of the substrate. The step of forming an insulating film extending along the sidewall and back surface of the substrate within the spaced space of the substrate; The step of forming a lower conductive film that is connected to a metal layer in the lower insulating film within the spaced space of the substrate and extends along the inner sidewall of the insulating film; as well as The step of forming an upper conductive film on the lower conductive film within the space between the substrates. The upper conductive film includes: The first part is located on the lower conductive film directly above the metal layer; as well as The second part extends along the inner sidewall of the lower conductive film on the sidewall of the substrate and has a spacer cross-sectional shape.

17. The method for manufacturing a back-illuminated image sensor according to claim 16, characterized in that, The lower conductive film and the upper conductive film are formed through the following steps: The step of forming a first conductive film on the metal layer and the insulating film; The step of forming a second conductive film on the first conductive film; The upper conductive film is completed by performing an etching process after forming a first photoresist film on the second conductive film. as well as The lower conductive film is completed by performing an etching process after forming a second photoresist film on the first conductive film and in the space between it and the substrate.

18. The method for manufacturing a back-illuminated image sensor according to claim 17, characterized in that, The distance between the side end of the first photoresist film and the sidewall of the adjacent substrate is in the range of 0.9 μm to 2.0 μm.

19. The method for manufacturing a back-illuminated image sensor according to claim 16, characterized in that, The steps for completing the upper conductive film include: The step of removing all the second conductive films located on the back side of the substrate.

20. The method for manufacturing a back-illuminated image sensor according to claim 16, characterized in that, One side of the lower conductive film is located on the back side of the substrate.

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