Image sensor

Abstract

The present invention provides an image sensor, which relates to the technical field of sensors. The image sensor includes a substrate, and the substrate has a photosensitive region, a floating region, and a transfer region disposed between the photosensitive region and the floating region; the photosensitive region includes an N-type doped region and a P-type doped region disposed on the N-type doped region; a channel layer is disposed in the transfer region, one side of the channel layer is in electrical contact with the N-type doped region, the other side of the channel layer is in electrical contact with the floating region, and the top surface of the channel layer is lower than the top surface of the P-type doped region. By making the top surface of the channel layer lower than the top surface of the photosensitive region, compared with the related art, the height of the transfer region in the vertical direction is reduced, and further the distance between the bottom surface of the photosensitive region and the channel layer is shortened, so that the charge transfer path and transfer time can be shortened, signal delay of the image sensor can be avoided, and the performance of the image sensor is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of sensors, and particularly to an image sensor. Background Art

[0002] An image sensor is a device that uses the photoelectric conversion function of optoelectronic devices to convert the optical image on the photosensitive surface into an electrical signal that is in a corresponding proportional relationship with the optical image, and is widely used in electronic products.

[0003] In related technologies, an image sensor generally includes a substrate and a photosensitive transistor, a transfer transistor, and a floating transistor disposed on the substrate. Among them, the photosensitive transistor and the floating transistor are respectively disposed on both sides of the transfer transistor. When incident light irradiates the photosensitive transistor, the photosensitive transistor forms charges and transfers the charges to the transfer transistor, and the transfer transistor is used to transfer the charges to the floating transistor to form an induced electrical signal.

[0004] However, there are defects in the charge transfer process, such as long transfer time and insufficient transfer, resulting in signal delay or trailing of the image sensor, which affects the performance of the image sensor. Summary of the Invention

[0005] In view of the above problems, embodiments of the present invention provide an image sensor for preventing signal delay or trailing of the image sensor, thereby improving the performance of the image sensor.

[0006] To achieve the above object, embodiments of the present invention provide the following technical solutions:

[0007] A first aspect of an embodiment of the present invention provides an image sensor, which includes: a substrate having a photosensitive region, a floating region, and a transfer region disposed between the photosensitive region and the floating region;

[0008] The photosensitive region includes an N-type doped region and a P-type doped region disposed on the N-type doped region;

[0009] A channel layer is disposed in the transfer region. One side of the channel layer is in electrical contact with the N-type doped region, the other side of the channel layer is in electrical contact with the floating region, and the top surface of the channel layer is lower than the highest surface of the P-type doped region.

[0010] For the above image sensor, the vertical distance between the top surface of the channel layer and the highest surface of the P-type doped region is less than or equal to the vertical distance between the top surface of the channel layer and the bottom surface of the N-type doped region.

[0011] For the above image sensor, the P-type doped region includes a first P-type doped region and a second P-type doped region connected to the first P-type doped region;

[0012] The first P-type doped region extends along a first direction, and there is a first preset angle between the extending direction of the second P-type doped region and the first direction. Moreover, the end of the second P-type doped region facing away from the first P-type doped region faces the substrate, and the top surface of the first P-type doped region constitutes the highest surface of the P-type doped region;

[0013] The end of the second P-type doped region facing away from the first P-type doped region is spaced apart from the channel layer.

[0014] The image sensor as described above, wherein the P-type doped region further includes a third P-type doped region connected to the first P-type doped region, and the third P-type doped region includes a U-shaped structure extending into the substrate.

[0015] The image sensor as described above, wherein the N-type doped region includes an extension portion that extends along the first direction below the transfer region;

[0016] Along a second direction, the top surface of the extension portion is spaced apart from the channel layer, and the first direction and the second direction are perpendicular to each other.

[0017] The image sensor as described above, wherein along the first direction, the ion concentration in the N-type doped region gradually increases from the side away from the channel layer to the side close to the channel layer.

[0018] The image sensor as described above, wherein along the second direction, the ion concentration in the N-type doped region gradually increases from the side away from the P-type doped region to the side close to the P-type doped region, and the second direction and the first direction are perpendicular to each other.

[0019] The image sensor as described above, wherein the ion concentration in the P-type doped region gradually increases from the side away from the channel layer to the side close to the channel layer.

[0020] The image sensor as described above, wherein there is a second preset angle between the extending direction of the channel layer and the first direction, and one end of the channel layer connected to the floating region faces away from the substrate.

[0021] The image sensor as described above, wherein the end of the channel layer close to the N-type doped region is disposed in contact with the N-type doped region.

[0022] The image sensor as described above, wherein the end of the P-type doped region close to the transfer region extends into the channel layer and has a first overlapping region with the channel layer;

[0023] Part of the end of the N-type doped region close to the transfer region extends into the channel layer and has a second overlapping region with the channel layer;

[0024] Along the first direction, the length of the second overlapping region is less than the length of the first overlapping region.

[0025] The image sensor as described above, wherein a gate oxide layer and a gate are further provided in the transfer region, the gate oxide layer is provided on the channel layer, and the gate is provided on a surface of the gate oxide layer facing away from the channel layer.

[0026] In the image sensor provided in the first aspect of the embodiment of the present invention, by making the top surface of the channel layer lower than the top surface of the photosensitive region, compared with the related art, the height of the transfer region in the vertical direction is reduced, and further the distance between the bottom surface of the photosensitive region and the channel layer is shortened, so that the transfer path and transfer time of the charges located at the bottom of the N-type doped region can be shortened, signal delay of the image sensor is avoided, and the performance of the image sensor is improved.

[0027] The second aspect of the embodiment of the present invention provides an image sensor, including a substrate, wherein a photosensitive region, a transfer region, and a floating region are provided in the substrate;

[0028] The photosensitive region includes an N-type doped region and a P-type doped region provided on the N-type doped region;

[0029] A channel layer is provided in the transfer region, one side of the channel layer is in electrical contact with the N-type doped region, the other side of the channel layer is in electrical contact with the floating region, and the top surface of the channel layer is flush with the top surface of the P-type doped region, and the bottom surface of the channel layer is flush with the bottom surface of the N-type doped region or the bottom surface of the channel layer is lower than the bottom surface of the N-type doped region.

[0030] The image sensor as described above, wherein the transfer region is disposed around the floating region, and the photosensitive region is disposed around the transfer region.

[0031] The image sensor as described above, wherein along the first direction, the ion concentration in the N-type doped region gradually increases from a side away from the channel layer to a side close to the channel layer.

[0032] The image sensor as described above, wherein along the second direction, the ion concentration in the N-type doped region gradually increases from a side away from the P-type doped region to a side close to the P-type doped region, and the second direction is perpendicular to the first direction.

[0033] The image sensor as described above, wherein the ion concentration in the P-type doped region gradually increases from a side away from the channel layer to a side close to the channel layer.

[0034] The image sensor as described above, wherein an end portion of the channel layer close to the photosensitive region is spaced apart from the P-type doping region.

[0035] The image sensor as described above, wherein the transfer transistor further includes a gate oxide layer and a gate electrode, the gate oxide layer is disposed on the channel layer, and the gate electrode is disposed on a surface of the gate oxide layer facing away from the channel layer.

[0036] In the image sensor provided in the second aspect of the embodiments of the present invention, by making the top surface of the channel layer flush with the top surface of the P-type doping region and the bottom surface of the channel layer flush with the N-type doping region, the contact area between the channel layer and the photosensitive region can be increased. In the vertical direction, the charges located at the bottom of the N-type doping region can be directly transmitted along the horizontal direction into the channel layer. Compared with the related art, the transmission path and transmission time of the charges located at the bottom of the N-type doping region can be shortened, signal delay of the image sensor can be avoided, and the performance of the image sensor is improved.

[0037] In addition to the technical problems solved by the embodiments of the present invention described above, the technical features constituting the technical solutions, and the beneficial effects brought by the technical features of these technical solutions, other technical problems that the image sensor provided by the embodiments of the present invention can solve, other technical features included in the technical solutions, and the beneficial effects brought by these technical features will be further described in detail in the specific implementation manners. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0039] Figure 1 Structural schematic diagram of the image sensor provided by the embodiments of the present invention Figure 1 ;

[0040] Figure 2 Structural schematic diagram of the image sensor provided by the embodiments of the present invention Figure 2 ;

[0041] Figure 3 Structural schematic diagram of the image sensor provided by the embodiments of the present invention Figure 3 ;

[0042] Figure 4 Structural schematic diagram of the image sensor provided by the embodiments of the present invention Figure 4 ;

[0043] Figure 5 ForFigure 4 Enlarged schematic view of area A;

[0044] Figure 6 Schematic structural view of forming a photoresist layer in the method for manufacturing an image sensor provided by an embodiment of the present invention;

[0045] Figure 7 Schematic structural view of forming a V-groove in the method for manufacturing an image sensor provided by an embodiment of the present invention;

[0046] Figure 8 Schematic structural view of forming a channel layer in the method for manufacturing an image sensor provided by an embodiment of the present invention;

[0047] Figure 9 Schematic structural view of forming a transfer transistor in the method for manufacturing an image sensor provided by an embodiment of the present invention;

[0048] Figure 10 Schematic structural view of forming a groove in the method for manufacturing an image sensor provided by an embodiment of the present invention;

[0049] Figure 11 Schematic structural view of forming a photosensitive region, a transfer region, and a floating region in the method for manufacturing an image sensor provided by an embodiment of the present invention;

[0050] Figure 12 Schematic structure of the image sensor provided by an embodiment of the present invention Figure 4 ;

[0051] Figure 13 is Figure 12 top view;

[0052] Figure 14 Schematic structure of the image sensor provided by an embodiment of the present invention Figure 5 ;

[0053] Figure 15 is Figure 13 top view.

[0054] Reference numerals:

[0055] 10: Substrate; 11: Photosensitive region;

[0056] 111: N-type doped region; 1111: Extension;

[0057] 112: P-type doped region; 1121: First P-type doped region;

[0058] 1122: Second P-type doped region; 1123: Third P-type doped region;

[0059] 12: Floating region; 13: Transfer region;

[0060] 20: Transfer transistor; 21: Channel layer;

[0061] 22: Gate oxide layer; 23: Gate;

[0062] 30: Photoresist layer; 31: Opening;

[0063] 40: V-groove; 41: First sidewall;

[0064] 42: Second sidewall; 50: Groove;

[0065] L1: First overlap region; L2: Second overlap region. Detailed implementation manner

[0066] An image sensor generally includes a substrate, which includes a photosensitive region, a floating region, and a transfer region disposed between the photosensitive region and the floating region. Among them, the top surfaces of the photosensitive region, the floating region, and the transfer region are flush. The transfer transistor is usually disposed above the transfer region, so that the top surface of the channel layer of the transfer transistor is flush with the top surface of the photosensitive region. When the photosensitive region receives incident light, charges are formed in the photosensitive region. In this way, the charges located at the bottom of the photosensitive region need to be transmitted vertically to the top of the photosensitive region along the direction perpendicular to the substrate in order to transmit the charges to the transfer transistor. That is, the transmission path of the charges at the bottom of the photosensitive region to the transfer transistor is relatively long, resulting in defects such as long transmission time and insufficient transmission during the transmission process of these charges, thereby causing signal delay or trailing in the image sensor and affecting the performance of the image sensor.

[0067] In view of the above technical problems, the embodiments of the present invention provide an image sensor. By making the top surface of the channel layer lower than the top surface of the photosensitive region, or making the channel layer penetrate through the top and bottom surfaces of the photosensitive region, the distance for the charges located at the bottom of the photosensitive region to be transmitted to the channel layer is shortened. In this way, the transmission path and transmission time of the charges can be shortened, signal delay or trailing of the image sensor can be avoided, and the performance of the image sensor is improved.

[0068] In order to make the above objects, features, and advantages of the embodiments of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0069] Such as Figure 1As shown in the figure, the image sensor provided by the embodiment of the present invention includes a substrate 10. The substrate 10 serves as a support component of the image sensor and is used to support other components disposed thereon. Among them, the substrate 10 can be made of semiconductor materials, and the semiconductor materials can be one or more of silicon, germanium, silicon germanium compounds, and silicon carbon compounds.

[0070] The substrate 10 is provided with a photosensitive area 11, a floating area 12, and a transmission area 13. Among them, the photosensitive area 11 can include an N-type doped area 111 and a P-type doped area 112 disposed on the N-type doped area 111. The interface between the N-type doped area 111 and the P-type doped area 112 forms a PN junction. Among them, the N-type doped area 111 and the P-type doped area 112 can be formed by doping ions into the substrate 10 through ion implantation technology. For example, phosphorus ions or arsenic ions can be implanted into the substrate 10 through ion implantation technology to form the N-type doped area 111; for another example, boron ions can be implanted into the substrate 10 through ion implantation technology to form the P-type doped area 112.

[0071] The transmission area 13 is disposed on one side of the photosensitive area 11 and is used to form a transmission transistor 20. Among them, the transmission transistor 20 can include a channel layer 21, a gate oxide layer 22, and a gate 23 sequentially disposed on the channel layer 21. One side of the channel layer 21 is in electrical contact with the N-type doped area 111, and the other side of the channel layer 21 is in electrical contact with the floating area 12.

[0072] The channel layer 21 can be formed by ion implantation technology. For example, boron ions can be implanted into the substrate corresponding to the transmission area 13 through ion implantation technology to make this part of the substrate form a P-type doped area, and this P-type doped area constitutes the channel layer 21 of the transmission transistor 20.

[0073] After the channel layer 21 is to be formed, a gate oxide layer 22 with a certain thickness can be formed on the channel layer through atomic layer deposition process or chemical vapor deposition process. The material of the gate oxide layer 22 can include insulating materials such as silicon oxide or silicon nitride. By using the setting of the gate oxide layer 22, the insulation between the channel layer 21 and the gate 23 can be realized.

[0074] After the gate oxide layer 22 is to be formed, a gate 23 with a certain thickness can be formed on the channel layer by using atomic layer deposition process or chemical vapor deposition process. The material of the gate 23 can include conductive materials such as tungsten.

[0075] The floating area 12 is disposed on the side of the transmission area 13 away from the photosensitive area 11, and the floating area 12 is generally an N-type doped area. That is to say, phosphorus ions or arsenic ions can be implanted into the floating area through ion implantation technology to form an N-type doped area.

[0076] When a certain voltage is applied to the gate 23 of the transfer transistor 20, the gate 23 will open the channel layer 21, causing the channel layer 21 to transform from a P-type doped region to an N-type doped region. In this way, one side of the channel layer 21 is connected to the N-type doped region 111 of the photosensitive region 11, and the other side of the channel layer 21 is connected to the N-type doped region of the floating region 12, enabling the charges in the photosensitive region 11 to be transmitted to the floating region 12 via the transfer region 13.

[0077] In this embodiment, the top surface of the channel layer 21 is lower than the highest surface of the P-type doped region 112. Compared with the technical solution in the related art where the top surface of the channel layer is flush with the highest surface of the P-type doped region, it is equivalent to reducing the height of the transfer region in the vertical direction, thereby shortening the distance between the bottom surface of the photosensitive region and the channel layer. This can shorten the transmission path and time of the charges located at the bottom of the photosensitive region, avoid signal delay in the image sensor, and improve the performance of the image sensor.

[0078] It should be noted that in this embodiment, if the top surface of the P-type doped region is a plane parallel to the first direction, the highest surface can be understood as the top surface; if the top surface of the P-type doped region is not a plane, the highest surface can be understood as the region of the top surface of the P-type doped region that is farthest from the bottom surface of the photosensitive region.

[0079] Further, continuing to refer to Figure 1 , the vertical distance between the top surface of the channel layer 21 and the highest surface of the P-type doped region 112 is less than or equal to the vertical distance between the top surface of the channel layer 21 and the bottom surface of the N-type doped region 111, that is, the vertical distance from the channel layer 21 to the highest surface of the photosensitive region 11 is less than or equal to the vertical distance from the channel layer 21 to the bottom surface of the photosensitive region 11. This can avoid excessively reducing the vertical distance from the channel layer 21 to the bottom surface of the photosensitive region, prevent increasing the transmission path and time of the charges located at the top surface of the photosensitive region, and ensure the performance of the image sensor.

[0080] In some embodiments, the P-type doped region 112 includes a first P-type doped region 1121 and a second P-type doped region 1122 connected to the first P-type doped region 1121; wherein, the first P-type doped region 1121 extends along the first direction, the extending direction of the second P-type doped region 1122 has a first preset angle with the first direction, and the end of the second P-type doped region 1122 facing away from the first P-type doped region 1121 faces the substrate 10. The top surface of the first P-type doped region constitutes the highest surface of the P-type doped region.

[0081] In this embodiment, the first direction is Figure 1 the X direction shown in

[0082] The first P-type doped region 1121 may extend along the vertical direction between the photosensitive region 11 and the floating region 12. The extending direction of the second P-type doped region 1122 trends downward obliquely with respect to the first direction, such that the end portion of the second P-type doped region 1122 away from the first P-type doped region 1121 is lower than the plane where the first P-type doped region 1121 is located, and the end portion of the second P-type doped region 1122 away from the first P-type doped region 1121 is spaced apart from the channel layer 21 of the transfer transistor 20. In this way, a receiving space can be provided for the gate of the transfer transistor, avoiding electrical contact between the gate and the second P-type doped region, and ensuring the yield of the image sensor.

[0083] It should be noted that the size of the first preset angle in this embodiment is not specifically limited. As long as the first preset angle is greater than 0 degrees and less than 90°, it can provide a receiving space for the gate of the transfer transistor.

[0084] Furthermore, as Figure 2 shown, the P-type doped region 112 further includes a third P-type doped region 1123 connected to the first P-type doped region 1121. The third P-type doped region 1123 includes a U-shaped structure extending into the substrate 10. That is, the third P-type doped region 1123 includes three successively connected first sub-doped regions, second sub-doped regions, and third sub-doped regions, and the third sub-doped region is connected to the first P-type doped region 1121.

[0085] Specifically, the first sub-doped region may extend along a direction perpendicular to the first direction, the second sub-doped region may extend along the first direction, the third sub-doped region may extend along a direction perpendicular to the first direction, and the extending direction of the third sub-doped region is opposite to the extending direction of the first sub-doped region, so that the first sub-doped region, the second sub-doped region, and the third sub-doped region enclose a U-shaped structure with an opening facing away from the substrate.

[0086] In this embodiment, by setting the third P-type doped region, the area of the PN junction in the photosensitive region can be increased, the ability of the photosensitive region to absorb incident light is enhanced, and thus the performance of the image sensor is improved.

[0087] In some embodiments, as Figure 2 shown, the N-type doped region 111 includes an extension portion 1111, and the extension portion 1111 extends along the first direction to the lower part of the transfer region 13.

[0088] The N-type doped region 111 also has an extension portion 1111 on the side close to the transfer region 13, and the extension portion 1111 extends along the first direction. That is, the extension portion 1111 extends along Figure 2It extends in the X direction until it extends below the transmission region 13. Among them, the extension portion 1111 can be a rectangular region. In this embodiment, through the setting of the extension portion, the area of the N-type doping region can be increased to expand the area of the region for storing charges in the photosensitive region, thereby improving the performance of the image sensor.

[0089] In some embodiments, along the second direction, that is, along the direction perpendicular to the substrate, namely Figure 2 and Figure 3 the Y direction in, the top surface of the extension portion 1111 is spaced apart from the channel layer 21. This can avoid electrical contact between the N-type doping region and the channel layer, thereby improving the yield of the image sensor.

[0090] It should be noted that the area of the extension portion is not specifically limited in this embodiment, as long as it can increase the area of the N-type doping region.

[0091] In some embodiments, along the first direction, the ion concentration in the N-type doping region 111 gradually increases from the side away from the channel layer 21 to the side close to the channel layer 21. That is, along Figure 1 and Figure 2 the X direction shown in, the ion concentration in the N-type doping region 111 increases sequentially from left to right, so that the ion concentration in the N-type doping region 111 forms a concentration gradient in the first direction. This concentration gradient forms a built-in electric field in the N-type doping region. By the built-in electric field, an additional transmission force is applied to the electrons located in the N-type doping region, so that the electrons located on the left side of the N-type doping region are transmitted to the right side of the N-type doping region faster, so as to improve the transmission ability of the electrons located in the N-type doping region along the first direction, prevent signal delay or trailing in the image sensor, and thus improve the performance of the image sensor.

[0092] Furthermore, along the second direction, the ion concentration in the N-type doping region 111 gradually increases from the side away from the P-type doping region 112 to the side close to the P-type doping region 112. The second direction is perpendicular to the first direction.

[0093] Along the direction perpendicular to the substrate 10, namely Figure 1 and Figure 2 the Y direction shown in, the ion concentration in the N-type doping region 111 increases sequentially from bottom to top, so that the ion concentration in the N-type doping region 111 forms a concentration gradient in the second direction. This concentration gradient forms a built-in electric field in the N-type doping region. By the built-in electric field, an additional transmission force is applied to the electrons located in the N-type doping region, so that the electrons located at the bottom of the N-type doping region are transmitted to the top of the N-type doping region faster, so as to improve the transmission ability of the electrons located in the N-type doping region along the second direction, prevent signal delay or trailing in the image sensor, and thus improve the performance of the image sensor.

[0094] Further, the ion concentration in the P-type doped region 112 gradually increases from the side away from the channel layer 21 to the side closer to the channel layer 21, that is, along the Figure 1 In the X direction shown in, the ion concentration in the P-type doped region 112 increases sequentially from left to right, so that the ion concentration in the P-type doped region 112 forms a concentration gradient in the first direction. This concentration gradient forms a built-in electric field in the P-type doped region, and an additional transmission force is applied to the holes located in the P-type doped region through the built-in electric field to improve the transmission ability of the holes located in the P-type doped region along the first direction, prevent signal delay or trailing in the image sensor, and thus improve the performance of the image sensor.

[0095] In some embodiments, as Figure 2 and Figure 3 shown, there is a second preset angle between the extending direction of the channel layer 21 and the first direction, and one end of the channel layer 21 connected to the floating region 12 faces away from the substrate 10. Taking the orientation shown in Figure 2 as an example, the channel layer extends in an inclined upward direction, which can reduce the manufacturing difficulty of the image sensor. It should be noted that the shape of the channel layer formed in this embodiment can have various choices. For example, as Figures 1 to 3 shown, the end of the channel layer 21 close to the N-type doped region 111 is arranged in contact with the N-type doped region 111.

[0096] Again, for example, Figure 4 and Figure 5 shown, the end of the P-type doped region 112 close to the transmission region 13 extends into the channel layer 21 and has a first overlapping region L1 with the channel layer 21.

[0097] Part of the end of the N-type doped region 111 close to the transmission region 13 extends into the channel layer 21 and has a second overlapping region L2 with the channel layer 21. Along the first direction, the length of the second overlapping region L2 is less than the length of the first overlapping region L1.

[0098] In this embodiment, by extending the P-type doped region and the N-type doped region into the channel layer, the transmission speed of charges can be increased, signal delay or trailing in the image sensor can be prevented, and thus the performance of the image sensor can be improved.

[0099] The embodiment of the present invention also provides a method for manufacturing an image sensor. The following only takes the structure shown in Figure 3 as an example to describe the method for manufacturing an image sensor in detail as follows. Specifically:

[0100] Provide a substrate 10.

[0101] As Figure 6As shown, a photoresist layer 30 is formed on the substrate 10, and the photoresist layer 30 is patterned to form an opening 31 in the photoresist layer. The opening 31 is used to expose the position where the transfer region 13 is located.

[0102] As Figure 7 shown, using an alkaline etching solution, the exposed part of the substrate 10 in the opening 31 is removed to form a V-groove 40 on the substrate. The V-groove 40 includes a first sidewall 41 and a second sidewall 42 connected to the first sidewall 41.

[0103] As Figure 8 shown, a mask is set on the substrate. The mask exposes the second sidewall 42, and then impurity ions are implanted into the second sidewall 42 using ion implantation technology to form a channel layer 21 on the second sidewall.

[0104] As Figure 9 shown, after the channel layer 21 is formed, a gate oxide layer 22 and a gate 23 can be sequentially formed on the channel layer 21 through a deposition process.

[0105] After the gate oxide layer 22 and the gate 23 are formed, a mask is provided again. The mask is used to block the transfer transistor, and then phosphorus ions or arsenic ions are implanted into the substrate using ion implantation technology to form an N-type doped region 111 of the photosensitive region 11 and a floating region 12 on the substrate.

[0106] When forming the N-type doped region of the photosensitive region, the concentration gradients in the first direction and the second direction can be formed in the photosensitive region by controlling the implantation angle and implantation energy in the ion implantation process, so as to form a built-in electric field in the photosensitive region. When the charges located in the photosensitive region are transmitted to the transfer transistor, under the action of the built-in electric field, the transmission speed and transmission efficiency of the charges can be improved, thereby improving the performance of the image sensor.

[0107] After the N-type doped region is formed, boron ions are implanted into the photosensitive region 11 again using ion implantation technology to form a P-type doped region on the surface of the photosensitive region to form the Figure 3 structure shown.

[0108] It should be noted that when forming the P-type doped region, the following process steps can also be included to achieve:

[0109] As Figure 10 shown, the photosensitive region 11 is patterned to form a groove 50 in the photosensitive region 11. The bottom wall of the groove 50 is spaced from the bottom surface of the substrate.

[0110] As Figure 11As shown, after the groove 50 is formed, boron ions are doped into the photosensitive area by ion implantation technology, so that the substrate exposed in the groove forms a third P-type doped area 1123, and a second P-type doped area 1122 and a first P-type doped area 1121 are formed on the substrate outside the groove in the photosensitive area.

[0111] After the doped area is formed, an insulating layer can be deposited in the groove 50 by physical vapor deposition process or chemical vapor deposition process, so that the top surface of the insulating layer is flush with the top surface of the substrate to form Figure 2 a structure, where the material of the insulating layer can be silicon or silicon oxide.

[0112] The image sensor provided by the embodiment of the present invention, such as from 12 to Figure 15 As shown, it includes a substrate 10. The substrate 10 serves as a support component of the image sensor and is used to support other components provided thereon. Among them, the substrate 10 can be made of a semiconductor material, and the semiconductor material can be one or more of silicon, germanium, silicon-germanium compound, and silicon-carbon compound.

[0113] The substrate 10 is provided with a photosensitive area 11, a transmission area 13, and a floating area 12; among them, the photosensitive area 11 can include an N-type doped area 111 and a P-type doped area 112 provided on the N-type doped area 111, and a PN junction is formed at the interface between the N-type doped area 111 and the P-type doped area 112.

[0114] It should be noted that the N-type doped area 111 and the P-type doped area 112 in this embodiment can be formed by doping ions into the substrate through ion implantation technology. For example, phosphorus ions or arsenic ions can be implanted into the substrate 10 through ion implantation technology to form the N-type doped area 111; and for another example, boron ions can be implanted into the substrate 10 through ion implantation technology to form the P-type doped area 112.

[0115] As Figure 12 and Figure 13 shown, the transmission area 13 is arranged on one side of the photosensitive area 11 and is used to arrange a transmission transistor 20. Among them, the transmission transistor 20 can include a channel layer 21, a gate oxide layer 22, and a gate 23 provided on the channel layer 21. One side of the channel layer 21 is in electrical contact with the N-type doped area 111, the other side of the channel layer 21 is in electrical contact with the floating area 12, and the top surface of the channel layer 21 is flush with the top surface of the P-type doped area 112, and the bottom surface of the channel layer 21 is flush with the bottom surface of the N-type doped area 111 or the bottom surface of the channel layer 21 is lower than the bottom surface of the N-type doped area.

[0116] In this embodiment, by making the top surface of the channel layer 21 flush with the top surface of the P-type doped region 112 and the bottom surface of the channel layer 21 flush with the bottom surface of the N-type doped region 111, the contact area between the channel layer and the photosensitive region can be increased. In the vertical direction, the charges located at the bottom of the N-type doped region can be directly transmitted horizontally into the channel layer. Compared with the related art, the transmission path and transmission time of the charges in the photosensitive region can be shortened, signal delay of the image sensor can be avoided, and the performance of the image sensor is improved.

[0117] In this embodiment, the bottom surface of the channel layer 21 can also be made lower than the bottom surface of the N-type doped region 111 to ensure that the charges in the photosensitive region can be completely transmitted to the transmission region, thereby improving the performance of the image sensor.

[0118] There are two possible implementation manners for the relative positions among the transmission region, the photosensitive region, and the floating region, which are specifically as follows:

[0119] A feasible implementation manner is as Figure 12 Figure 13 shown. The transmission region 13 is arranged between the photosensitive region 11 and the floating region 12, and the transmission region 13, the photosensitive region 11, and the floating region 12 are sequentially connected along the first direction. Among them, a transmission transistor 20 is arranged in the transmission region 13, and the transmission transistor 20 is used to transmit charges from the photosensitive region 11 to the floating region 12.

[0120] When a certain voltage is applied to the gate of the transmission transistor, the gate will open the channel layer, causing the channel layer to be converted from a P-type doped region to an N-type doped region, making one side of the channel layer communicate with the N-type doped region of the photosensitive region, and the other side of the channel layer communicate with the N-type doped region of the floating region, thereby realizing the function of transmitting the charges in the photosensitive region to the floating region through the transmission region.

[0121] Furthermore, in this embodiment, the bottom surface of the channel layer of the transmission transistor 20 facing away from the gate 23 can extend into the substrate 10. That is to say, along the second direction, the height of the channel layer 21 is higher than the height of the photosensitive region 11. This can enable the charges at the bottom of the photosensitive region to be completely transmitted from the bottom of the channel layer 21 into the floating region 12, improving the transmission time and transmission efficiency of the charges, avoiding signal delay or trailing of the image sensor, and improving the performance of the image sensor.

[0122] Another feasible implementation manner is as Figure 14 and Figure 15 shown. The transmission region 13 is arranged around the floating region 12, the photosensitive region 11 is arranged around the transmission region 13, and a transmission transistor 20 is arranged in the transmission region 13. The transmission transistor 20 is used to transmit charges from the photosensitive region 11 to the floating region 12.

[0123] Exemplarily, as Figure 15As shown, that is, the transmission region 13 may be provided with a plurality of transmission transistors 20, and the plurality of transmission transistors 20 are arranged at intervals along the circumferential direction of the floating region 12, so that the transmission transistors 20 are annularly distributed. In this way, the charge located in the photosensitive region can be transmitted to the floating region through the plurality of transmission transistors, which can shorten the transmission path and transmission time of the charge, improve the transmission speed and transmission efficiency, and thus improve the performance of the image sensor.

[0124] It should be noted that no matter how the photosensitive region, the transmission region and the floating region are arranged, the end of the channel layer 21 close to the photosensitive region 11 is spaced from the P-type doped region 112 to avoid electrical contact between the channel layer and the P-type doped region and reduce the yield of the image sensor.

[0125] In some embodiments, along the first direction, the ion concentration in the N-type doped region 111 gradually increases from the side away from the channel layer 21 to the side close to the channel layer 21, that is, along Figure 12 the X direction shown in, the ion concentration in the N-type doped region 111 increases in turn from left to right, so that the ion concentration in the N-type doped region 111 forms a concentration gradient in the first direction. This concentration gradient forms a built-in electric field in the N-type doped region, and an additional transmission force is applied to the charge located in the photosensitive region through the built-in electric field to improve the transmission ability of the charge, prevent signal delay or trailing in the image sensor, and improve the performance of the image sensor.

[0126] Furthermore, along the second direction, the ion concentration in the N-type doped region 111 gradually increases from the side away from the P-type doped region 112 to the side close to the P-type doped region 112, and the second direction is perpendicular to the first direction.

[0127] Along the direction perpendicular to the substrate, that is, Figure 10 the Y direction shown in, the ion concentration in the N-type doped region 111 increases in turn from bottom to top, so that the ion concentration in the N-type doped region 111 forms a concentration gradient in the second direction. Since there is a concentration gradient in the N-type doped region 111, a built-in electric field will be formed in the N-type doped region 111. An additional transmission force is applied to the charge located in the photosensitive region through the built-in electric field to improve the transmission ability of the charge in the photosensitive region, prevent signal delay or trailing in the image sensor, and thus improve the performance of the image sensor.

[0128] Furthermore, the ion concentration in the P-type doped region 112 gradually increases from the side away from the channel layer 21 to the side close to the channel layer 21, that is, along Figure 10In the X direction shown in the figure, the ion concentration in the P-type doped region 112 increases sequentially from left to right, such that a concentration gradient is formed in the first direction for the ion concentration in the P-type doped region 112. Since there is a concentration gradient within the P-type doped region 112, a built-in electric field will be formed within the P-type doped region 112. An additional transmission force is applied to the charges located in the photosensitive region through the built-in electric field to improve the transmission ability of the charges located in the photosensitive region, prevent signal delay or trailing in the image sensor, and improve the performance of the image sensor.

[0129] An embodiment of the present invention also provides a method for manufacturing an image sensor. Only taking the Figure 14 structure shown as an example, the method for manufacturing the image sensor is described in detail as follows. Specifically:

[0130] Provide a substrate.

[0131] Pattern the substrate to form fins on the substrate.

[0132] Form a gate oxide layer on the fins.

[0133] Form a conductive layer on the substrate. The conductive layer covers the fins and the gate oxide layer, and then pattern the conductive layer to form a plurality of spaced-apart gates on the conductive layer, wherein the fins, the gate oxide layer, and the gates constitute a transfer transistor.

[0134] After the transfer transistor is formed, use an epitaxial technique to form a silicon substrate on the substrate, wherein the top surface of the silicon substrate is flush with the bottom surface of the gate oxide layer.

[0135] Finally, use an ion implantation technique to form a photosensitive region and a floating region on the silicon substrate.

[0136] The embodiments or implementation manners in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other.

[0137] In the description of this specification, the description with reference to terms such as "one implementation manner", "some implementation manners", "illustrative implementation manner", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials, or characteristics described in connection with the implementation manner or example are included in at least one implementation manner or example of the present invention.

[0138] In this specification, the illustrative expressions of the above terms do not necessarily refer to the same implementation manner or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more implementation manners or examples.

[0139] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An image sensor, characterized in that, It includes a substrate, within which there are a photosensitive region, a floating region, and a transfer region disposed between the photosensitive region and the floating region; The photosensitive region includes an N-type doped region and a P-type doped region disposed on the N-type doped region; A channel layer is disposed in the transfer region. One side of the channel layer is in electrical contact with the N-type doped region, and the other side of the channel layer is in electrical contact with the floating region. Moreover, the top surface of the channel layer is lower than the highest surface of the P-type doped region; There is a second preset angle between the extending direction of the channel layer and the first direction, and one end of the channel layer connected to the floating region faces away from the substrate; The end portion of the P-type doped region close to the transfer region extends into the channel layer and has a first overlapping region with the channel layer; some end portions of the N-type doped region close to the transfer region extend into the channel layer and have a second overlapping region with the channel layer; along the first direction, the length of the second overlapping region is less than the length of the first overlapping region; Along the first direction, the ion concentration in the N-type doped region gradually increases from the side away from the channel layer to the side close to the channel layer; along the second direction, the ion concentration in the N-type doped region gradually increases from the side away from the P-type doped region to the side close to the P-type doped region, and the second direction is perpendicular to the first direction; the ion concentration in the P-type doped region gradually increases from the side away from the channel layer to the side close to the channel layer.

2. The image sensor according to claim 1, wherein The vertical distance between the top surface of the channel layer and the highest surface of the P-type doped region is less than or equal to the vertical distance between the top surface of the channel layer and the bottom surface of the N-type doped region.

3. The image sensor according to claim 1, characterized in that, The P-type doped region includes a first P-type doped region and a second P-type doped region connected to the first P-type doped region; The first P-type doped region extends along the first direction. There is a first preset angle between the extending direction of the second P-type doped region and the first direction, and the end portion of the second P-type doped region facing away from the first P-type doped region faces the substrate. The top surface of the first P-type doped region constitutes the highest surface of the P-type doped region; The end portion of the second P-type doped region facing away from the first P-type doped region is spaced from the channel layer.

4. The image sensor according to claim 3, characterized in that, The P-type doped region further includes a third P-type doped region connected to the first P-type doped region, and the third P-type doped region includes a U-shaped structure extending into the substrate.

5. The image sensor according to any one of claims 1-4, characterized in that, The N-type doped region includes an extension portion that extends along the first direction to the lower part of the transfer region; Along the second direction, the top surface of the extension portion is spaced from the channel layer, and the first direction is perpendicular to the second direction.

6. The image sensor according to any one of claims 1-4, characterized in that, The transfer region is further provided with a gate oxide layer and a gate. The gate oxide layer is disposed on the channel layer, and the gate is disposed on the surface of the gate oxide layer facing away from the channel layer.

7. An image sensor, characterized in that, It includes a substrate, within which there are a photosensitive region, a transfer region, and a floating region; The photosensitive region includes an N-type doped region and a P-type doped region disposed on the N-type doped region; A channel layer is provided in the transmission region. One side of the channel layer is in electrical contact with the N-type doped region, and the other side of the channel layer is in electrical contact with the floating region. Moreover, the top surface of the channel layer is flush with the top surface of the P-type doped region, and the bottom surface of the channel layer is flush with the bottom surface of the N-type doped region or the bottom surface of the channel layer is lower than the bottom surface of the N-type doped region; The transmission region is arranged to surround the floating region, and the photosensitive region is arranged to surround the transmission region; wherein, a plurality of transmission transistors are provided in the transmission region, and the plurality of transmission transistors are arranged at intervals along the circumferential direction of the floating region, so that the transmission transistors are distributed in a ring shape; Along the first direction, the ion concentration in the N-type doped region gradually increases from the side away from the channel layer to the side close to the channel layer; along the second direction, the ion concentration in the N-type doped region gradually increases from the side away from the P-type doped region to the side close to the P-type doped region, and the second direction is perpendicular to the first direction; the ion concentration in the P-type doped region gradually increases from the side away from the channel layer to the side close to the channel layer.

8. The image sensor according to claim 7, characterized in that, The end of the channel layer close to the photosensitive region is arranged at an interval from the P-type doped region.

9. The image sensor according to claim 8, characterized in that, The transmission transistor further includes a gate oxide layer and a gate electrode. The gate oxide layer is provided on the channel layer, and the gate electrode is provided on the surface of the gate oxide layer facing away from the channel layer.

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