Image sensor and its formation method

Abstract

An image sensor and its forming method are disclosed. The image sensor includes: a substrate comprising a pixel region and a logic region; a first photoelectric doped region located within the pixel region, the surface of which is exposed on the substrate surface; and a shielding gate structure located on the pixel region, the shielding gate structure comprising a dielectric layer and a shielding gate layer, wherein the thickness of the shielding gate layer differs in color pixel units of different color types. The shielding gate structure on the pixel region allows for the reduction of dark current generation by applying an operating voltage to the shielding gate structure, thereby improving the imaging quality of the image sensor. By setting different thicknesses of the shielding gate layers in the color pixel units of different color types, the light intensity after passing through the shielding gate layers of the color pixel units of different color types is made approximately proportional to the light intensity before passing through the filter structures of different color types, thus better reproducing true colors and improving the imaging quality of the image sensor.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to an image sensor and a method for forming the same. Background Technology

[0002] An image sensor is a semiconductor device that converts light signals into electrical signals.

[0003] Image sensors are divided into CMOS (Complementary Metal Oxide Semiconductor) image sensors and CCD (Charge Coupled Device) image sensors. CMOS image sensors have advantages such as simple manufacturing process, easy integration with other devices, small size, light weight, low power consumption, and low cost. Therefore, with the development of image sensing technology, CMOS image sensors are increasingly replacing CCD image sensors in various electronic products. Currently, CMOS image sensors are widely used in still digital cameras, digital camcorders, medical imaging devices, and automotive imaging devices.

[0004] However, the performance of existing image sensors still needs improvement. Summary of the Invention

[0005] The technical problem solved by this invention is to provide an image sensor and a method for forming the same, so as to improve the performance of the image sensor.

[0006] To address the aforementioned problems, the present invention provides an image sensor comprising: a plurality of color pixel units of different color types, wherein each color pixel unit comprises: a substrate, the substrate comprising a pixel region and a logic region, the pixel region and the logic region being adjacent; a first photoelectric doped region located within the pixel region, the surface of the substrate exposing the surface of the first photoelectric doped region, the first photoelectric doped region containing first ions; and a shielding gate structure located on the pixel region, the shielding gate structure comprising a dielectric layer and a shielding gate layer located on the dielectric layer, wherein the thickness of the shielding gate layer in the color pixel units of different color types is different.

[0007] Optionally, the color pixel units of several color types include: red pixel units, green pixel units, and blue pixel units.

[0008] Optionally, the thickness of the shielding gate layer in the red pixel unit is greater than the thickness of the shielding gate layer in the green pixel unit; the thickness of the shielding gate layer in the green pixel unit is greater than the thickness of the shielding gate layer in the blue pixel unit.

[0009] Optionally, the thickness of the shielding gate layer in the red pixel unit is 0.05 micrometers to 0.5 micrometers; the thickness of the shielding gate layer in the green pixel unit is 0.04 micrometers to 0.4 micrometers; and the thickness of the shielding gate layer in the blue pixel unit is 0.03 micrometers to 0.3 micrometers.

[0010] Optionally, each of the color pixel units further includes: a shielding layer located on the surface of the first photoelectric doped region, wherein the conductivity type of the doped ions in the shielding layer is opposite to that of the first ions; and the shielding gate structure is located on the shielding layer.

[0011] Optionally, the substrate includes a first side and a second side opposite to each other, the first side of the substrate exposing the surface of the first photoelectric doped region; the shielding gate structure is located on the first photoelectric doped region.

[0012] Optionally, each of the color pixel units further includes a transmission gate structure and a reset gate structure located on the logic region.

[0013] Optionally, the transmission gate structure surrounds the reset gate structure.

[0014] Optionally, each color pixel unit further includes: a second photoelectric doping region located within the first photoelectric doping region, the second photoelectric doping region having a second ion, the second ion having the same conductivity type as the first ion, and the concentration of the second ion being greater than the concentration of the first ion.

[0015] Optionally, the transmission gate structure is adjacent to the second photoelectric doped region.

[0016] Optionally, each color pixel unit further includes a floating doped region and a drain region located in the logic region on both sides of the reset gate structure, wherein the floating doped region is located between the transfer gate structure and the reset gate structure.

[0017] Optionally, each of the color pixel units further includes: a first isolation doped region located within the logic region and a portion of the pixel region, wherein the conductivity type of the doped ions in the first isolation doped region is opposite to that of the first ions; the floating doped region, the drain region, and a portion of the second photoelectric doped region are located within the first isolation doped region.

[0018] Optionally, the shielded gate structure surrounds the logic region.

[0019] Optionally, the substrate further includes: a second isolation doped region located between adjacent pixel regions, wherein the conductivity type of the doped ions in the second isolation doped region is opposite to that of the first ions, and the second isolation doped region is adjacent to the first photoelectric doped region; and an isolation structure located in the second isolation doped region.

[0020] Optionally, the dielectric layer is made of silicon oxide; the shielding gate layer is made of silicon.

[0021] Optionally, the substrate contains a third ion whose conductivity type is opposite to that of the first ion.

[0022] Optionally, the substrate has a well region containing the third ion; the pixel region and the logic region are located within the well region.

[0023] Optionally, the first ion includes an N-type ion, which includes phosphorus ions, arsenic ions, or antimony ions; the third ion includes a P-type ion, which includes boron ions, borofluorine ions, or indium ions.

[0024] Optionally, each of the color pixel units further includes: a filter structure located on the pixel area, and a lens located on the filter structure.

[0025] Accordingly, the present invention also provides a method for forming an image sensor, comprising: forming a plurality of color pixel units of different color types, wherein the method for forming each color pixel unit comprises: providing a substrate, the substrate comprising a pixel region and a logic region, the pixel region and the logic region being adjacent; forming a first photoelectric doped region within the pixel region, the surface of the substrate exposing the surface of the first photoelectric doped region, the first photoelectric doped region containing a first ion; forming a shielding gate structure on the pixel region, the shielding gate structure comprising a dielectric layer and a shielding gate layer located on the dielectric layer, the thickness of the shielding gate layer being different in the color pixel units of different color types.

[0026] Optionally, the color pixel units of several color types include: red pixel units, green pixel units, and blue pixel units.

[0027] Optionally, the thickness of the shielding gate layer in the red pixel unit is greater than the thickness of the shielding gate layer in the green pixel unit; the thickness of the shielding gate layer in the green pixel unit is greater than the thickness of the shielding gate layer in the blue pixel unit.

[0028] Optionally, the thickness of the shielding gate layer in the red pixel unit is 0.05 micrometers to 0.5 micrometers; the thickness of the shielding gate layer in the green pixel unit is 0.04 micrometers to 0.4 micrometers; and the thickness of the shielding gate layer in the blue pixel unit is 0.03 micrometers to 0.3 micrometers.

[0029] Optionally, before forming the shielding gate structure on the pixel region, the method further includes: forming a shielding layer on the surface of the first photoelectric doped region, wherein the conductivity type of the doped ions in the shielding layer is opposite to that of the first ions; and the shielding gate structure is located on the shielding layer.

[0030] Optionally, the substrate includes a first side and a second side opposite to each other, the first side of the substrate exposing the surface of the first photoelectric doped region; the shielding gate structure is located on the first photoelectric doped region.

[0031] Optionally, it also includes forming a transmission gate structure and a reset gate structure on the logic region.

[0032] Optionally, the transmission gate structure surrounds the reset gate structure.

[0033] Optionally, the transmission gate structure and the reset gate structure are formed simultaneously.

[0034] Optionally, before forming the shielding gate structure on the pixel region, the method further includes: forming a second photoelectric doped region within the first photoelectric doped region, the second photoelectric doped region having a second ion, the second ion having the same conductivity type as the first ion, and the concentration of the second ion being greater than the concentration of the first ion.

[0035] Optionally, the transmission gate structure is adjacent to the second photoelectric doped region.

[0036] Optionally, after forming the transmission gate structure and the reset gate structure, the method further includes: forming a floating doped region and a drain region in the logic regions on both sides of the reset gate structure, wherein the floating doped region is located between the transmission gate structure and the reset gate structure.

[0037] Optionally, the substrate further includes: a first isolation doped region located within the logic region and a portion of the pixel region, wherein the conductivity type of the doped ions in the first isolation doped region is opposite to that of the first ions; the floating doped region, the drain region, and a portion of the second photoelectric doped region are located within the first isolation doped region.

[0038] Optionally, the shielded gate structure surrounds the logic region.

[0039] Optionally, the substrate further includes: a second isolation doped region located between adjacent pixel regions, wherein the conductivity type of the doped ions in the second isolation doped region is opposite to that of the first ions, and the second isolation doped region is adjacent to the first photoelectric doped region; and an isolation structure located within the second isolation doped region.

[0040] Optionally, the dielectric layer is made of silicon oxide; the shielding gate layer is made of silicon.

[0041] Optionally, the substrate contains a third ion, the conductivity type of which is opposite to that of the first ion.

[0042] Optionally, the substrate has a well region containing the third ion; the pixel region and the logic region are located within the well region.

[0043] Optionally, the first ion includes an N-type ion, which includes phosphorus ions, arsenic ions, or antimony ions; the third ion includes a P-type ion, which includes boron ions, borofluorine ions, or indium ions.

[0044] Optionally, it also includes: forming a filter structure on the second surface of the pixel area; and forming a lens on the filter structure.

[0045] Optionally, the formation process of the first photoelectric doped region includes an ion implantation process.

[0046] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0047] In the image sensor of this invention, the pixel region has a shielding gate structure. By applying a working voltage to the shielding gate structure, positive charges are induced to accumulate on the substrate surface, forming a hole passivation layer. This hole passivation layer traps electrons, preventing them from entering the pixel region, thereby reducing dark current generation and improving the image quality of the image sensor. Furthermore, because the shielding gate layer has different absorption coefficients for different wavelengths of light, the light intensity incident on the diode region varies, leading to color distortion. Therefore, by setting different thicknesses of the shielding gate layers in the color pixel units of different color types, the light intensity after passing through the shielding gate layer of each color pixel unit is made approximately proportional to the light intensity before passing through the filter structure of each color type. This allows for better reproduction of true colors, thus improving the image quality of the image sensor.

[0048] Furthermore, the shielding gate structure is located on the surface of the first photoelectric doped region, thereby enabling the application of a negative voltage to the shielding gate structure to induce the accumulation of a large number of positive charges at the interface between the shielding gate structure and the substrate to form a hole passivation layer. The hole passivation layer can trap electrons to block electrons from entering the pixel region, thereby reducing the generation of dark current and improving the imaging quality of the image sensor.

[0049] Furthermore, the surface of the first photoelectric doped region has a shielding layer, and the conductivity type of the doped ions in the shielding layer is opposite to that of the first ions. The shielding gate structure is located on the shielding layer. Thus, by applying zero or a positive voltage to the shielding gate structure, electrons can be induced to accumulate at the interface between the shielding layer and the shielding gate structure, thereby generating a large number of holes in the first photoelectric doped region. These holes can trap electrons, preventing them from entering the pixel region, thereby reducing dark current generation and improving the imaging quality of the image sensor.

[0050] Furthermore, the first photoelectric doped region contains a second photoelectric doped region. The second ion in the second photoelectric doped region has the same conductivity type as the first ion, and the concentration of the second ion is greater than the concentration of the first ion. This results in the second photoelectric doped region and the first photoelectric doped region having a larger potential, which is beneficial for the readout of electrons in the pixel region.

[0051] Furthermore, the transmission gate structure surrounds the reset gate structure, and the shielding gate structure surrounds the logic region. This structure can increase the radiation resistance of the image sensor and prevent leakage current.

[0052] Furthermore, a second isolation doped region is provided between adjacent pixel regions. The conductivity type of the doped ions in the second isolation doped region is opposite to that of the first ions. The second isolation doped region has an isolation structure. The second isolation doped region can isolate the isolation structure and the pixel region to reduce the possibility of interface defects between the isolation structure and the pixel region.

[0053] Furthermore, the logic region and part of the pixel region have a first isolation doped region. The conductivity type of the doped ions in the first isolation doped region is opposite to that of the first ions. The floating doped region, the drain region, and part of the second photoelectric doped region are located within the first isolation doped region. Thus, the first isolation doped region can isolate the pixel region from the floating doped region and the drain region, thereby reducing the leakage current between the pixel region and the floating doped region and the drain region.

[0054] The image sensor formation method of the present invention, by forming a shielding gate structure on the pixel area, induces positive charges to accumulate on the substrate surface and form a hole passivation layer by applying a voltage to the shielding gate structure. This hole passivation layer traps electrons to prevent them from entering the pixel area, thereby reducing dark current generation and improving the image quality of the image sensor. Furthermore, since the shielding gate layer has different absorption coefficients for different wavelengths of light, the light intensity incident on the diode region varies, leading to color distortion. Therefore, by setting different thicknesses of the shielding gate layers in the color pixel units of different color types, the light intensity after passing through the shielding gate layer of the color pixel unit of different color types is made approximately proportional to the light intensity before passing through the filter structure of different color types, thus better restoring true colors and improving the image quality of the image sensor.

[0055] Furthermore, the shielding gate structure is located on the surface of the first photoelectric doped region, thereby enabling the application of a negative voltage to the shielding gate structure to induce the accumulation of a large number of positive charges at the interface between the shielding gate structure and the substrate to form a hole passivation layer. The hole passivation layer can trap electrons to block electrons from entering the pixel region, thereby reducing the generation of dark current and improving the imaging quality of the image sensor.

[0056] Furthermore, the first photoelectric doped region has a shielding layer on its surface, and the conductivity type of the doped ions in the shielding layer is opposite to that of the first ions. The shielding gate structure is located on the shielding layer. Therefore, by applying zero or a positive voltage to the shielding gate structure, electrons can be induced to accumulate at the interface between the shielding layer and the shielding gate structure, thereby generating a large number of holes in the first photoelectric doped region. These holes can trap electrons, preventing them from entering the pixel area, thus reducing dark current generation and improving the imaging quality of the image sensor. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of the cross-sectional structure of a pixel unit in an image sensor;

[0058] Figures 2 to 8 This is a schematic diagram of the structure of each step in the image sensor image formation method according to an embodiment of the present invention;

[0059] Figures 9 to 10 This is a schematic diagram of the steps in the image sensor image formation method according to another embodiment of the present invention. Detailed Implementation

[0060] As described in the background section, the performance of existing image sensors still needs improvement, which will be explained below with reference to specific figures.

[0061] Figure 1 This is a schematic diagram of the cross-sectional structure of a pixel unit in an image sensor.

[0062] Please refer to Figure 1 The system includes: a substrate 100, comprising a first surface and a second surface opposite to each other, the substrate 100 including a pixel region I and a logic region II, the pixel region I and the logic region II being adjacent; a first photoelectric doped region 101 located within the pixel region I, the first photoelectric doped region 101 containing a first ion; a second photoelectric doped region 102 located within the first photoelectric doped region 101, the dopant ions in the second photoelectric doped region 102 having the same conductivity type as the first ion, and the dopant ion concentration in the second photoelectric doped region 102 being greater than the concentration of the first ion; a shielding layer 103 located on the surface of the first photoelectric doped region 101 and part of the surface of the second photoelectric doped region 102, the first surface of the substrate exposing the shielding layer 103, the shielding layer 103 containing a second ion, the second ion having the opposite conductivity type to the first ion; a transmission gate structure and a reset gate structure located on the logic region II, the transmission gate structure being adjacent to the second photoelectric doped region 102, and so on. The transmission gate structure surrounds the reset gate structure. The transmission gate structure includes a gate dielectric layer 104 and a transmission gate layer 106 located on the gate dielectric layer 104. The reset gate structure includes the gate dielectric layer 104 and a reset gate layer 105 located on the gate dielectric layer 104. The gate dielectric layer 104 is also located on the surface of the pixel region I. A first isolation doped region 109 is located within the logic region II and part of the pixel region I. A part of the second photoelectric doped region 102 is located within the first isolation doped region 109. A drain region 107 and a floating doped region 108 are located within the first isolation doped regions 109 on both sides of the reset gate structure. The floating doped region 108 is located between the transmission gate structure and the reset gate structure. A second isolation doped region 110 is located between adjacent pixel regions I. The second isolation doped region 110 is adjacent to the first photoelectric doped region 101. An isolation structure 111 is located within the second isolation doped region 110. The isolation structure 111 is adjacent to the shielding layer 103.

[0063] In the image sensor pixel unit, in order to reduce dark current, a shielding layer 103 is formed between the gate dielectric layer 104 and the first photoelectric doped region 101. The second ion in the shielding layer 103 has a conductivity type opposite to that of the first ion, and the second ion is a P-type ion. Thus, the shielding layer 103 can capture defect electrons between the first photoelectric doped region 101 and the gate dielectric layer 104, so that the defect states of the first photoelectric doped region 101 and the gate dielectric layer 104 are occupied, thereby blocking electrons from entering the pixel region I, and thus reducing dark current.

[0064] However, during ionizing radiation, high-speed charged particles collide elastically with the atomic nuclei of the image sensor material, causing lattice shifts and defects in the material. This results in reduced minority carrier lifetime, lower pure doping concentration, decreased mobility, decreased transistor current gain, and increased leakage current. Specifically, in the oxide (SiO2) gate dielectric layer 104 of the image sensor pixel unit, electron-hole pairs are generated. Electrons escape to the transmission gate layer 106 and the reset gate layer 105, while holes are transported to the interface between the gate dielectric layer 104 and the silicon substrate. Some holes are captured by defects at the interface, causing threshold changes; others enter the pixel region I, generating severe dark current, affecting the imaging quality of the CMOS image sensor.

[0065] Based on this, the present invention provides an image sensor and a method for forming the same. The pixel region has a shielding gate structure, which allows positive charges to accumulate on the substrate surface and form a hole passivation layer by applying a working voltage to the shielding gate structure. This hole passivation layer traps electrons, preventing them from entering the pixel region, thereby reducing dark current generation and improving the image quality of the image sensor. Furthermore, by setting different thicknesses for the shielding gate layers in the color pixel units of different color types, the light intensity after passing through the shielding gate layers of the color pixel units of different color types is made approximately proportional to the light intensity before passing through the filter structures of different color types. This allows for better reproduction of true colors, further improving the image quality of the image sensor.

[0066] To make the above-mentioned objectives, features and beneficial effects of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0067] Figures 2 to 8 This is a schematic diagram of the steps in the image sensor image formation method according to an embodiment of the present invention.

[0068] Several color pixel units of different color types are formed, and the specific formation process of each color pixel unit is described in [reference needed]. Figures 2 to 8.

[0069] Please refer to Figure 2 A substrate 200 is provided, the substrate 200 including a pixel region I and a logic region II, the pixel region I and the logic region II being adjacent to each other, and the substrate 200 including a first surface 201 and a second surface 202 opposite to each other.

[0070] In this embodiment, the substrate 200 contains a third ion, which includes a P-type ion, and the P-type ion includes boron ions, boron-fluorine ions, or indium ions.

[0071] In other embodiments, the substrate has a well region containing a third ion; the pixel region and the logic region are located within the well region.

[0072] In this embodiment, the substrate 200 further includes: a second isolation doped region 203 located between adjacent pixel regions I; an isolation structure 204 located within the second isolation doped region 203, wherein the conductivity type of the doped ions in the second isolation doped region 203 is the same as that of the third ion; and a first isolation doped region 205 located within the logic region II and part of the pixel region I, wherein the conductivity type of the doped ions in the first isolation doped region 205 is the same as that of the third ion.

[0073] The isolation structure 204 is used to isolate optical crosstalk between adjacent pixel regions I; the second isolation doped region 203 can isolate the isolation structure 204 and the pixel region I to reduce the possibility of interface defects between the isolation structure 204 and the pixel region I.

[0074] Since the subsequently formed floating doped region and drain region are located within the first isolation doped region 205, the first isolation doped region 205 can isolate the pixel region I from the floating doped region and the drain region, thereby reducing the leakage current between the pixel region I and the floating doped region and the drain region.

[0075] The isolation structure 204 is made of a dielectric material, which includes one or more combinations of silicon oxide, silicon nitride, silicon carbide, silicon carbide, silicon oxynitride, aluminum oxide, aluminum nitride, silicon carbide nitride, and silicon carbide nitride. In this embodiment, the isolation structure 204 is made of silicon oxide.

[0076] In this embodiment, the substrate 200 is made of silicon.

[0077] In other embodiments, the substrate material includes silicon carbide, silicon germanium, a multi-element semiconductor material composed of group III-V elements, silicon-on-insulator (SOI), or germanium-on-insulator (GOI). The multi-element semiconductor material composed of group III-V elements includes InP, GaAs, GaP, InAs, InSb, InGaAs, or InGaAsP.

[0078] Please refer to Figure 3 A first photoelectric doped region 206 is formed in the pixel region I. The first surface 201 of the substrate 200 exposes the surface of the first photoelectric doped region 206. The first photoelectric doped region 206 contains a first ion, and the conductivity type of the first ion is opposite to that of the third ion.

[0079] In this embodiment, the first photoelectric doped region 206 is formed by ion implantation.

[0080] In this embodiment, the first ion includes an N-type ion, which includes phosphorus ions, arsenic ions, or antimony ions.

[0081] In this embodiment, the second isolation doped region 203 is adjacent to the first photoelectric doped region 206.

[0082] The conductivity type of the first ion is opposite to that of the third ion, that is, the first photoelectric doped region 206 and the substrate 200 can be inversely related to each other to form a diode region.

[0083] Please continue to refer to this. Figure 3 A second photoelectric doping region 207 is formed within the first photoelectric doping region 206. The second photoelectric doping region 207 has a second ion with the same conductivity type as the first ion, and the concentration of the second ion is greater than the concentration of the first ion.

[0084] In this embodiment, a portion of the second photoelectric doped region 207 is located within the first isolation doped region 205.

[0085] In this embodiment, the second ion includes an N-type ion, which includes phosphorus ions, arsenic ions, or antimony ions.

[0086] In this embodiment, the second photoelectric doped region 207 is formed using an ion implantation process.

[0087] In this embodiment, the conductivity type of the second ion is the same as that of the first ion, and the concentration of the second ion is greater than that of the first ion, thereby making the second photoelectric doped region 207 and the first photoelectric doped region 206 have a large potential difference, which is beneficial to the readout of electrons in the pixel region I.

[0088] In other embodiments, the second photoelectric doped region may not be formed.

[0089] Please refer to Figures 4 to 6 A shielding gate structure is formed on the pixel region I. The shielding gate structure is located on the first photoelectric doped region 206. The shielding gate structure includes a dielectric layer 208 and a shielding gate layer 209 located on the dielectric layer 208. The thickness of the shielding gate layer 209 in the color pixel unit of different color types is different.

[0090] In this embodiment, by forming a shielding gate structure on the pixel region I, a voltage can be applied to the shielding gate structure to induce positive charges to accumulate on the first surface of the substrate 200, forming a hole passivation layer. This hole passivation layer traps electrons, preventing them from entering the pixel region I, thereby reducing dark current generation and improving the image quality of the image sensor. Furthermore, since the shielding gate layer 209 has different absorption coefficients for different wavelengths of light, the light intensity incident on the diode region varies, leading to color distortion. Therefore, by setting different thicknesses for the shielding gate layer 209 in the color pixel units of different color types, the light intensity after passing through the shielding gate layer 209 of the color pixel units of different color types is made to be close to the ratio of the light intensity before passing through the filter structure of different color types. This allows for better reproduction of true colors, thereby improving the image quality of the image sensor.

[0091] In this embodiment, the shielding gate structure is located on the surface of the first photoelectric doping region 206. By applying a negative voltage to the shielding gate structure, a large number of positive charges are induced to accumulate at the interface between the shielding gate structure and the substrate 200 to form a hole passivation layer. The hole passivation layer can trap electrons to block electrons from entering the pixel region I, thereby reducing the generation of dark current and improving the imaging quality of the image sensor.

[0092] In this embodiment, the color pixel units of several color types include: red pixel units (such as...) Figure 6 As shown), green pixel units (such as...) Figure 5 (as shown) and blue pixel units (such as) Figure 4 (As shown).

[0093] In this embodiment, the thickness of the shielding gate layer 209 in the red pixel unit is greater than the thickness of the shielding gate layer 209 in the green pixel unit; the thickness of the shielding gate layer 209 in the green pixel unit is greater than the thickness of the shielding gate layer 209 in the blue pixel unit.

[0094] In this embodiment, the thickness of the shielding gate layer 209 in the red pixel unit is 0.05 micrometers to 0.5 micrometers; the thickness of the shielding gate layer 209 in the green pixel unit is 0.04 micrometers to 0.4 micrometers; and the thickness of the shielding gate layer 209 in the blue pixel unit is 0.03 micrometers to 0.3 micrometers.

[0095] In this embodiment, the dielectric layer 208 is made of silicon oxide; the shielding gate layer 209 is made of silicon.

[0096] In this embodiment, the method further includes forming a transmission gate structure and a reset gate structure on the logic region II, wherein the transmission gate structure is adjacent to the second photoelectric doped region 207.

[0097] The transmission gate structure includes: the dielectric layer 208 and the transmission gate layer 210 located on the dielectric layer 208; the reset gate structure includes: the dielectric layer 208 and the reset gate layer 211 located on the dielectric layer 208.

[0098] In this embodiment, the method for forming the shielding gate structure, the transmission gate structure, and the reset gate structure includes: forming a dielectric layer 208 on a first surface 201 of a substrate 200; forming a first sacrificial layer (not shown) on the dielectric layer 208, the first sacrificial layer exposing the surface of the dielectric layer 208 in the blue pixel unit; forming a first gate material layer (not shown) on the surface of the dielectric layer 208 in the blue pixel unit; performing a first patterning process on the first gate material layer until the surface of the dielectric layer 208 in the blue pixel unit is exposed, forming the shielding gate structure in the blue pixel unit; removing the first sacrificial layer; after removing the first sacrificial layer, forming a second sacrificial layer (not shown), the second sacrificial layer exposing the surface of the dielectric layer 208 in the green pixel unit, and the surface of the dielectric layer 208 on the logic region II in the blue pixel unit and the red pixel unit; in the green pixel unit A second gate material layer (not shown) is formed on the surface of the dielectric layer 208 in the green pixel unit; the second gate material layer is subjected to a second patterning process until the surface of the dielectric layer 208 in the green pixel unit, and the surface of the dielectric layer 208 on the logic region II in the blue pixel unit and the red pixel unit are exposed, forming the shielding gate structure, the transmission gate structure and the reset gate structure in the green pixel unit; the second sacrificial layer is removed; after removing the second sacrificial layer, a third sacrificial layer (not shown) is formed, the third sacrificial layer exposing the surface of the dielectric layer 208 in the red pixel unit; a third gate material layer (not shown) is formed on the surface of the dielectric layer 208 in the red pixel unit; the third gate material layer is subjected to a third patterning process until the surface of the dielectric layer 208 in the red pixel unit is exposed, forming the shielding gate structure in the red pixel unit; the third sacrificial layer is removed.

[0099] In this embodiment, the shielding gate structure surrounds the logic region II; the transmission gate structure surrounds the reset gate structure. This structure increases the radiation resistance of the image sensor and prevents leakage current.

[0100] Please Figure 5 Continue to refer to Figure 7 and Figure 8 , Figure 7 for Figure 8 A schematic diagram of the cross-sectional structure along section line AA1. Figure 8 for Figure 7A top view shows that after the transmission gate structure and the reset gate structure are formed, a floating doped region 212 and a drain region 213 are formed in the logic region II on both sides of the reset gate structure. The floating doped region 212 is located between the transmission gate structure and the reset gate structure, and the floating doped region 212 and the drain region 213 are located in the first isolation doped region 205.

[0101] In this embodiment, the floating doped region 212 and the drain region 213 are located within the first isolation doped region 205, thereby the first isolation doped region 205 can isolate the pixel region I from the floating doped region 212 and the drain region 213, so as to reduce the leakage current between the pixel region I and the floating doped region 212 and the drain region 213.

[0102] In this embodiment, the method for forming the floating doped region 212 and the drain region 213 includes: removing the dielectric layer 208 on the logic region II on both sides of the reset gate structure; and performing ion implantation on the logic region II on both sides of the reset gate structure to form the floating doped region 212 and the drain region 213.

[0103] In this embodiment, the conductivity type of the doped ions in the floating doped region 212 and the drain region 213 is the same as that of the first ion. The doped ions in the floating doped region 212 and the drain region 213 include N-type ions, which include phosphorus ions, arsenic ions, or antimony ions.

[0104] In this embodiment, after forming the floating doped region 212 and the drain region 213, the method further includes: forming a filter structure (not shown) on the first surface 201 of the pixel region I; and forming a lens (not shown) on the filter structure.

[0105] In this embodiment, the lens is used to allow light to pass through the lens and enter the pixel area I, and the filter structure is used to allow light of a specific wavelength to enter the pixel area I.

[0106] Accordingly, embodiments of the present invention also provide an image sensor; please refer to [further details]. Figure 7 and Figure 8The system includes: color pixel units of several color types, wherein each color pixel unit includes: a substrate 200, the substrate 200 including a pixel region I and a logic region II, the pixel region I and the logic region II being adjacent; a first photoelectric doped region 206 located in the pixel region I, the surface of the substrate 200 exposing the surface of the first photoelectric doped region 206, the first photoelectric doped region 206 containing a first ion; and a shielding gate structure located on the pixel region I, the shielding gate structure including a dielectric layer 208 and a shielding gate layer 209 located on the dielectric layer 208, the thickness of the shielding gate layer 209 being different in the color pixel units of different color types.

[0107] In this embodiment, the color pixel units of several color types include: red pixel units (such as...) Figure 6 As shown), green pixel units (such as...) Figure 5 (as shown) and blue pixel units (such as) Figure 4 (As shown).

[0108] In this embodiment, the thickness of the shielding gate layer 209 in the red pixel unit is greater than the thickness of the shielding gate layer 209 in the green pixel unit; the thickness of the shielding gate layer 209 in the green pixel unit is greater than the thickness of the shielding gate layer 209 in the blue pixel unit.

[0109] In this embodiment, the thickness of the shielding gate layer 209 in the red pixel unit is 0.05 micrometers to 0.5 micrometers; the thickness of the shielding gate layer 209 in the green pixel unit is 0.04 micrometers to 0.4 micrometers; and the thickness of the shielding gate layer 209 in the blue pixel unit is 0.03 micrometers to 0.3 micrometers.

[0110] In this embodiment, the substrate 200 includes a first surface 201 and a second surface 202 facing each other, the first surface 201 of the substrate 200 exposes the surface of the first photoelectric doped region 206; the shielding gate structure is located on the first photoelectric doped region 206.

[0111] In this embodiment, it further includes a transmission gate structure and a reset gate structure located on the logic region II.

[0112] In this embodiment, the transmission gate structure surrounds the reset gate structure.

[0113] In this embodiment, it further includes: a second photoelectric doping region 207 located within the first photoelectric doping region 206, the second photoelectric doping region 207 having a second ion, the second ion having the same conductivity type as the first ion, and the concentration of the second ion being greater than the concentration of the first ion.

[0114] In this embodiment, the transmission gate structure is adjacent to the second photoelectric doped region 207.

[0115] In this embodiment, it further includes: a floating doped region 212 and a drain region 213 located in the logic region II on both sides of the reset gate structure, wherein the floating doped region 212 is located between the transmission gate structure and the reset gate structure.

[0116] In this embodiment, it further includes: a first isolation doped region 205 located within the logic region II and a portion of the pixel region I, wherein the conductivity type of the doped ions in the first isolation doped region 205 is opposite to that of the first ions; the floating doped region 212, the drain region 213, and a portion of the second photoelectric doped region 207 are located within the first isolation doped region 205.

[0117] In this embodiment, the shielding gate structure surrounds the logic region II.

[0118] In this embodiment, the substrate 200 further includes: a second isolation doped region 203 located between adjacent pixel regions I, wherein the conductivity type of the doped ions in the second isolation doped region 203 is opposite to that of the first ions, and the second isolation doped region 203 is adjacent to the first photoelectric doped region 207; and an isolation structure 204 located in the second isolation doped region 203.

[0119] The transmission gate structure includes: the dielectric layer 208 and the transmission gate layer 210 located on the dielectric layer 208; the reset gate structure includes: the dielectric layer 208 and the reset gate layer 211 located on the dielectric layer 208.

[0120] In this embodiment, the dielectric layer 208 is made of silicon oxide; the shielding gate layer 209 is made of silicon.

[0121] In this embodiment, the substrate 200 contains a third ion, the conductivity type of which is opposite to that of the first ion.

[0122] In other embodiments, the substrate has a well region containing a third ion; the pixel region and logic region are located within the well region.

[0123] In this embodiment, the first ion includes an N-type ion, which includes phosphorus ions, arsenic ions, or antimony ions; the third ion includes a P-type ion, which includes boron ions, boron-fluorine ions, or indium ions.

[0124] In this embodiment, it also includes: a filter structure (not shown) located on the first surface 201 of the pixel area I, and a lens (not shown) located on the filter.

[0125] In this embodiment, the pixel region I of the image sensor has a shielding gate structure. By applying a working voltage to the shielding gate structure, positive charges are induced to accumulate on the surface of the substrate 200, forming a hole passivation layer. This hole passivation layer traps electrons, preventing them from entering the pixel region I, thereby reducing dark current generation and improving the image quality of the image sensor. Furthermore, since the shielding gate layer 209 has different absorption coefficients for different wavelengths of light, the light intensity incident on the diode region varies, leading to color distortion. Therefore, by setting different thicknesses of the shielding gate layer 209 in the color pixel units of different color types, the light intensity after passing through the shielding gate layer 209 of the color pixel units of different color types is made to be close to the ratio of the light intensity before passing through the filter structure of different color types. This allows for better reproduction of true colors, thereby improving the image quality of the image sensor.

[0126] In this embodiment, the shielding gate structure is located on the surface of the first photoelectric doping region 206. By applying a negative voltage to the shielding gate structure, a large number of positive charges are induced to accumulate at the interface between the shielding gate structure and the substrate 200 to form a hole passivation layer. The hole passivation layer can trap electrons to block electrons from entering the pixel region I, thereby reducing the generation of dark current and improving the imaging quality of the image sensor.

[0127] Figures 9 to 10 This is a schematic diagram of the steps in the image sensor image formation method according to another embodiment of the present invention.

[0128] Please refer to Figure 9 , Figure 9 In order to be in Figure 3 Based on the structural schematic diagram, a shielding layer 301 is formed on the surface of the first photoelectric doped region 206, and the conductivity type of the doped ions in the shielding layer 301 is opposite to that of the first ions.

[0129] In this embodiment, the shielding layer 301 is used to occupy the defects at the interface between the substrate 200 and the subsequently formed dielectric layer, thereby blocking electrons from entering the pixel area I, thereby reducing the generation of dark current and improving the imaging quality of the image sensor.

[0130] In this embodiment, the shielding layer 301 also extends to a portion of the surface of the second photoelectric doped region 207.

[0131] In this embodiment, the doping ions of the shielding layer 301 are P-type ions, including boron ions, boron-fluorine ions, or indium ions.

[0132] In this embodiment, the shielding layer 301 is formed using an ion implantation process.

[0133] Please refer to Figure 10 , Figure 10 In order to be in Figure 5 Based on the structural diagram, after the shielding layer 301 is formed, a shielding gate structure is formed on the pixel area I. The shielding gate structure is located on the shielding layer 301. The shielding gate structure includes a dielectric layer 302 and a shielding gate layer 303 located on the dielectric layer 302. The thickness of the shielding gate layer 303 in the color pixel unit of different color types is different.

[0134] In this embodiment, the dielectric layer 302 is made of silicon oxide; the shielding gate layer 303 is made of silicon.

[0135] In this embodiment, the pixel region I of the image sensor has a shielding gate structure. By applying a working voltage to the shielding gate structure, positive charges are induced to accumulate on the surface of the substrate 200, forming a hole passivation layer. This hole passivation layer traps electrons, preventing them from entering the pixel region I, thereby reducing dark current generation and improving the image quality of the image sensor. Furthermore, since the shielding gate layer 303 has different absorption coefficients for different wavelengths of light, the light intensity incident on the diode region varies, leading to color distortion. Therefore, by setting different thicknesses for the shielding gate layer 303 in the color pixel units of different color types, the light intensity after passing through the shielding gate layer 303 of the color pixel units of different color types is made approximately equal to the light intensity before passing through the filter structure of different color types. This allows for better reproduction of true colors, thereby improving the image quality of the image sensor.

[0136] In this embodiment, the first photoelectric doped region 206 has a shielding layer 301 on its surface. The conductivity type of the doped ions in the shielding layer 301 is opposite to that of the first ions. The shielding gate structure is located on the surface of the shielding layer 301. By applying zero voltage or a positive voltage to the shielding gate structure, electrons can be induced to accumulate at the interface between the shielding layer 301 and the shielding gate structure. This results in a large number of holes being generated in the first photoelectric doped region 206. These holes can trap electrons to prevent them from entering the pixel region I, thereby reducing the generation of dark current and improving the imaging quality of the image sensor.

[0137] In this embodiment, the method further includes forming a transmission gate structure and a reset gate structure on the first surface 201 of the logic region II, wherein the transmission gate structure is adjacent to the second photoelectric doped region 207.

[0138] The transmission gate structure includes a dielectric layer 302 and a transmission gate layer 304 located on the dielectric layer 302; the reset gate structure includes a dielectric layer 302 and a reset gate layer 305 located on the dielectric layer 302.

[0139] Please refer to the process, materials, and methods for forming the shielding gate structure, transmission gate structure, and reset gate structure. Figures 4 to 6 The relevant explanations will not be repeated here.

[0140] Please continue to refer to this. Figure 10 A floating doped region 306 and a drain region 307 are formed in the logic region II on both sides of the reset gate structure. The floating doped region 306 is located between the transmission gate structure and the reset gate structure.

[0141] In this embodiment, the floating doped region 306 and the drain region 307 are located within the first isolation doped region 205.

[0142] In this embodiment, the processes, materials, and methods for forming the floating doped region 306 and the drain region 307 are described in reference to [reference needed]. Figure 7 and Figure 8 The relevant explanations will not be repeated here.

[0143] Accordingly, embodiments of the present invention also provide an image sensor; please refer to [further details]. Figure 10 A plurality of color pixel units of different color types, wherein each color pixel unit includes: a substrate 200, the substrate 200 including a pixel region I and a logic region II, the pixel region I and the logic region II being adjacent; a first photoelectric doped region 206 located in the pixel region I, the surface of the substrate 200 exposing the surface of the first photoelectric doped region 206, the first photoelectric doped region 206 containing a first ion; a shielding gate structure located on the pixel region I, the shielding gate structure including a dielectric layer 302 and a shielding gate layer 303 located on the dielectric layer 302, the thickness of the shielding gate layer 303 being different in the color pixel units of different color types.

[0144] In this embodiment, it further includes: the shielding layer 301 located on the surface of the first photoelectric doping region 206, wherein the conductivity type of the doped ions in the shielding layer 301 is opposite to that of the first ions; and the shielding gate structure is located on the shielding layer 301.

[0145] In this embodiment, the substrate 200 includes a first surface 201 and a second surface 202 facing each other, the first surface 201 of the substrate 200 exposes the surface of the first photoelectric doped region 206; the shielding gate structure is located on the first photoelectric doped region 206.

[0146] In this embodiment, it also includes a transmission gate structure and a reset gate structure located on the first surface 201 of the logic region II.

[0147] In this embodiment, the transmission gate structure surrounds the reset gate structure.

[0148] In this embodiment, it further includes: a second photoelectric doping region 207 located within the first photoelectric doping region 206, the second photoelectric doping region 207 having a second ion, the second ion having the same conductivity type as the first ion, and the concentration of the second ion being greater than the concentration of the first ion.

[0149] In this embodiment, the transmission gate structure is adjacent to the second photoelectric doped region 207.

[0150] In this embodiment, it further includes a floating doped region 306 and a drain region 307 located in the logic region II on both sides of the reset gate structure, wherein the floating doped region 306 is located between the transmission gate structure and the reset gate structure.

[0151] In this embodiment, it further includes: a first isolation doped region 205 located within the logic region II and a portion of the pixel region I, wherein the conductivity type of the doped ions in the first isolation doped region 205 is opposite to that of the first ions; the floating doped region 306, the drain region 307, and a portion of the second photoelectric doped region 207 are located within the first isolation doped region 205.

[0152] In this embodiment, the shielding gate structure surrounds the logic region II.

[0153] In this embodiment, the substrate 200 further includes: a second isolation doped region 203 located between adjacent pixel regions I, wherein the conductivity type of the doped ions in the second isolation doped region 203 is opposite to that of the first ions, and the second isolation doped region 203 is adjacent to the first photoelectric doped region 207; and an isolation structure 204 located in the second isolation doped region 203.

[0154] In this embodiment, the transmission gate structure includes a dielectric layer 302 and a transmission gate layer 304 located on the dielectric layer 302; the reset gate structure includes a dielectric layer 302 and a reset gate layer 305 located on the dielectric layer 302.

[0155] In this embodiment, the dielectric layer 302 is made of silicon oxide; the shielding gate layer 303 is made of silicon.

[0156] In this embodiment, the substrate 200 contains a third ion, the conductivity type of which is opposite to that of the first ion.

[0157] In other embodiments, the substrate has a well region containing a third ion; the pixel region and logic region are located within the well region.

[0158] In this embodiment, the first ion includes an N-type ion, which includes phosphorus ions, arsenic ions, or antimony ions; the third ion includes a P-type ion, which includes boron ions, boron-fluorine ions, or indium ions.

[0159] In this embodiment, it also includes: a filter structure (not shown) located on the first surface 201 of the pixel area I, and a lens (not shown) located on the filter.

[0160] In this embodiment, the pixel region I of the image sensor has a shielding gate structure. Applying a voltage to the shielding gate structure induces positive charges to accumulate on the first surface of the substrate 200, forming a hole passivation layer. This hole passivation layer traps electrons, preventing them from entering the pixel region I, thereby reducing dark current and improving the image quality of the image sensor. Furthermore, since the shielding gate layer 303 has different absorption coefficients for different wavelengths of light, the light intensity incident on the diode region varies, leading to color distortion. Therefore, by setting different thicknesses for the shielding gate layer 303 in the color pixel units of different color types, the light intensity after passing through the shielding gate layer 303 of the color pixel units of different color types is made approximately equal to the light intensity before passing through the filter structure of different color types. This allows for better reproduction of true colors, thereby improving the image quality of the image sensor.

[0161] In this embodiment, the first photoelectric doped region 206 has a shielding layer 301 on its surface. The conductivity type of the doped ions in the shielding layer 301 is opposite to that of the first ions. The shielding gate structure is located on the surface of the shielding layer 301. By applying zero voltage or a positive voltage to the shielding gate structure, electrons can be induced to accumulate at the interface between the shielding layer 301 and the shielding gate structure. This results in a large number of holes being generated in the first photoelectric doped region 206. These holes can trap electrons to prevent them from entering the pixel region I, thereby reducing the generation of dark current and improving the imaging quality of the image sensor.

[0162] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. An image sensor, characterized by, The application relates to a color pixel unit of several color categories. The color pixel unit comprises: a substrate comprising a pixel region and a logic region, the pixel region and the logic region being adjacent; a first photoelectrically doped region located in the pixel region, a surface of the first photoelectrically doped region being exposed on a surface of the substrate, and the first photoelectrically doped region having first ions; a shielding gate structure located on the pixel region, the shielding gate structure comprising a dielectric layer and a shielding gate layer located on the dielectric layer, the thickness of the shielding gate layer being different in the color pixel units of different color categories; wherein the shielding gate structure is located on the surface of the first photoelectrically doped region, a negative voltage is loaded on the shielding gate structure, positive charges are induced to gather at the interface between the shielding gate structure and the substrate to form holes, and the holes trap electrons to prevent the electrons from entering the pixel region to generate dark current.

2. The image sensor of claim 1, wherein, The color pixel unit of several color categories comprises a red pixel unit, a green pixel unit and a blue pixel unit.

3. The image sensor of claim 2, wherein, The thickness of the shielding gate layer in the red pixel unit is greater than that in the green pixel unit, and the thickness of the shielding gate layer in the green pixel unit is greater than that in the blue pixel unit.

4. The image sensor of claim 3, wherein, The thickness of the shielding gate layer in the red pixel unit is 0.05-0.5 microns, the thickness of the shielding gate layer in the green pixel unit is 0.04-0.4 microns, and the thickness of the shielding gate layer in the blue pixel unit is 0.03-0.3 microns.

5. The image sensor of claim 1, wherein, Each color pixel unit further comprises a shielding layer located on the surface of the first photoelectrically doped region, the conductive type of the doped ions in the shielding layer being opposite to that of the first ions; the shielding gate structure is located on the shielding layer; wherein the shielding gate structure is located on the surface of the shielding layer, a zero voltage or a positive voltage is loaded on the shielding gate structure, electrons are induced to gather on the surface of the shielding layer and the shielding gate structure, holes are generated in the first photoelectrically doped region, the holes trap electrons to prevent the electrons from entering the pixel region to generate dark current, and the shielding layer is used for occupying defects at the interface between the substrate and the dielectric layer in the shielding gate structure to prevent the electrons from entering the pixel region to generate dark current.

6. The image sensor of claim 1, wherein, The substrate comprises opposite first and second surfaces, the first surface of the substrate exposing the surface of the first photoelectrically doped region; and the shielding gate structure is located on the first photoelectrically doped region.

7. The image sensor of claim 1, wherein, Each color pixel unit further comprises a transfer gate structure and a reset gate structure located on the logic region.

8. The image sensor of claim 7, wherein, The transfer gate structure surrounds the reset gate structure.

9. The image sensor of claim 7, wherein, Each color pixel unit further comprises a second photoelectrically doped region located in the first photoelectrically doped region, the second photoelectrically doped region having second ions, the conductive type of the second ions being the same as that of the first ions, and the concentration of the second ions being greater than that of the first ions.

10. The image sensor of claim 7, wherein, Each of the color pixel units further comprises a floating doping region and a drain region in the logic region on both sides of the reset gate structure, and the floating doping region is located between the transfer gate structure and the reset gate structure.

11. The image sensor of claim 10, wherein, Each of the color pixel units further comprises a first isolation doping region in the logic region and in part of the pixel region, and a doping ion conductive type of the first isolation doping region is opposite to a conductive type of the first ion; and the floating doping region, the drain region, and part of the second photoelectric doping region are located in the first isolation doping region.

12. The image sensor of claim 1, wherein, The shield gate structure surrounds the logic region.

13. The image sensor of claim 1, wherein, The substrate further comprises a second isolation doping region between adjacent pixel regions, and a doping ion conductive type in the second isolation doping region is opposite to a conductive type of the first ion; and the second isolation doping region is adjacent to the first photoelectric doping region; and an isolation structure in the second isolation doping region.

14. The image sensor of claim 1, wherein, A material of the dielectric layer comprises silicon oxide; and a material of the shield gate layer comprises silicon.

15. The image sensor of claim 1, wherein, The substrate has a third ion therein, and a conductive type of the third ion is opposite to a conductive type of the first ion.

16. The image sensor of claim 15, wherein, The substrate has a well region therein, and the third ion is in the well region; and the pixel region and the logic region are in the well region.

17. The image sensor of claim 16, wherein, The first ion comprises an N-type ion, and the N-type ion comprises a phosphorus ion, an arsenic ion, or an antimony ion; and the third ion comprises a P-type ion, and the P-type ion comprises a boron ion, a boron fluoride ion, or an indium ion.

18. The image sensor of claim 1, wherein, Each of the color pixel units further comprises a filter structure on the pixel region, and a lens on the filter structure.

19. A method of forming an image sensor, comprising: The method comprises: forming color pixel units of several color categories, wherein a forming method of each of the color pixel units comprises: providing a substrate, the substrate comprising a pixel region and a logic region, and the pixel region and the logic region being adjacent; forming a first photoelectric doping region in the pixel region, a surface of the substrate exposing a surface of the first photoelectric doping region, and the first photoelectric doping region having a first ion therein; forming a shield gate structure on the pixel region, the shield gate structure comprising a dielectric layer and a shield gate layer on the dielectric layer, and thicknesses of the shield gate layers in the color pixel units of different color categories being different; and the shield gate structure being located on the surface of the first photoelectric doping region, a negative voltage being loaded on the shield gate structure, positive charges being induced to gather at an interface between the shield gate structure and the substrate to form holes, and the holes trapping electrons to prevent the electrons from entering the pixel region to cause dark current.

20. The method for forming an image sensor according to claim 19, wherein, The color pixel units of several color categories comprise a red pixel unit, a green pixel unit, and a blue pixel unit.

21. The method for forming an image sensor according to claim 20, wherein, The thickness of the shield gate layer in the red pixel unit is greater than the thickness of the shield gate layer in the green pixel unit; and the thickness of the shield gate layer in the green pixel unit is greater than the thickness of the shield gate layer in the blue pixel unit.

22. The method for forming an image sensor according to claim 21, wherein The thickness of the shielding gate layer in the red pixel unit is 0.05-0.5 microns; the thickness of the shielding gate layer in the green pixel unit is 0.04-0.4 microns; and the thickness of the shielding gate layer in the blue pixel unit is 0.03-0.3 microns.

23. The method for forming a photo sensor according to Claim 19, wherein Before forming the shielding gate structure on the pixel region, the method further comprises: forming a shielding layer on the surface of the first photoelectrically doped region, the conductive type of the doped ions in the shielding layer being opposite to the conductive type of the first ions; and the shielding gate structure is located on the shielding layer; wherein the shielding gate structure is located on the surface of the shielding layer, and a zero voltage or a positive voltage is applied to the shielding gate structure to induce the accumulation of electrons on the surface of the shielding layer and the shielding gate structure, so that holes are generated in the first photoelectrically doped region, and the holes trap the electrons to block the electrons from entering the pixel region to induce dark current; and the shielding layer is used to occupy the defects at the interface between the substrate and the dielectric layer in the shielding gate structure, thereby blocking the electrons from entering the pixel region to induce dark current.

24. The method for forming a photo sensor according to Claim 19, wherein, The substrate comprises opposite first and second surfaces, and the first surface of the substrate exposes the surface of the first photoelectrically doped region; and the shielding gate structure is located on the first photoelectrically doped region.

25. The method for forming a photo sensor according to Claim 19, wherein The method further comprises: forming a transfer gate structure and a reset gate structure on the logic region.

26. The method for forming a image sensor according to claim 25, wherein, The transfer gate structure surrounds the reset gate structure.

27. The method for forming a photo sensor according to Claim 25, wherein The transfer gate structure and the reset gate structure are formed simultaneously.

28. The method for forming a image sensor of claim 25, wherein, Before forming the shielding gate structure on the pixel region, the method further comprises: forming a second photoelectrically doped region in the first photoelectrically doped region, the second photoelectrically doped region having second ions, the conductive type of the second ions being the same as the conductive type of the first ions, and the concentration of the second ions being greater than the concentration of the first ions.

29. The method for forming a photo sensor according to Claim 25, wherein After forming the transfer gate structure and the reset gate structure, the method further comprises: forming a floating doped region and a drain region in the logic region on both sides of the reset gate structure, the floating doped region being located between the transfer gate structure and the reset gate structure.

30. The method for forming a photosensor according to Claim 29, wherein The substrate further comprises: a first isolation doped region located in the logic region and part of the pixel region, the conductive type of the doped ions in the first isolation doped region being opposite to the conductive type of the first ions; and the floating doped region, the drain region, and part of the second photoelectrically doped region are located in the first isolation doped region.

31. The method for forming a photo sensor according to Claim 19, wherein The shielding gate structure surrounds the logic region.

32. The method for forming a photo sensor according to Claim 19, wherein The substrate further comprises: a second isolation doped region located between adjacent pixel regions, the conductive type of the doped ions in the second isolation doped region being opposite to the conductive type of the first ions, the second isolation doped region being adjacent to the first photoelectrically doped region; and an isolation structure located in the second isolation doped region.

33. The method for forming a photo sensor according to Claim 19, wherein The material of the dielectric layer comprises silicon oxide; and the material of the shielding gate layer comprises silicon.

34. The method for forming a photo sensor according to Claim 19, wherein, The substrate has third ions therein, the conductive type of the third ions being opposite to the conductive type of the first ions.

35. The method for forming a photosensor according to Claim 34, wherein The substrate has a well region therein, the well region having the third ions therein; and the pixel region and the logic region are located in the well region.

36. The method for forming a photosensor according to Claim 34, wherein The first ion comprises an N-type ion, and the N-type ion comprises a phosphorus ion, an arsenic ion or an antimony ion; the third ion comprises a P-type ion, and the P-type ion comprises a boron ion, a boron-fluorine ion or an indium ion.

37. The method for forming a photo sensor according to Claim 19, wherein Also comprising: forming a filter structure on the second surface of the pixel region; forming a lens on the filter structure.

38. The method for forming a photo sensor according to Claim 19, wherein, The forming process of the first photoelectric doped region comprises an ion implantation process.

Images