Pixel unit, image sensor and terminal equipment

Abstract

The invention relates to a pixel unit, an image sensor and terminal equipment, and relates to the technical field of semiconductor devices, and the pixel unit comprises a storage device, an isolation structure and a shading device. The storage device comprises a charge storage part and a storage grid located on the charge storage part; the isolation structure is arranged around the charge storage part, and a first gap is formed between the isolation structure and the charge storage part; the shading device is located on the isolation structure and at least covers part of the first gap. Since the shading device shields the first gap, most of ambient light which originally enters the charge storage part through the first gap is blocked by the shading device, so that the amount of ambient light received by the charge storage part can be effectively reduced, and the parasitic light sensitivity of the image sensor comprising the pixel unit is further effectively reduced; and the final imaging quality of the image sensor is ensured.

Description

Technical Field

[0001] The present disclosure relates to the technical field of semiconductor devices, and in particular to a pixel unit, an image sensor and a terminal device. Background Art

[0002] In the related art, a global shutter image sensor generally includes a storage device for storing charges and an isolation structure surrounding the storage device. However, there is generally a large gap between the storage device and the isolation structure, and ambient light can easily penetrate the gap into the charge storage portion of the storage device, thereby increasing the parasitic light sensitivity of the image sensor and causing distortion of the final image presented. Summary of the invention

[0003] The embodiments of the present disclosure provide a pixel unit, an image sensor, and a terminal device, which reduce the parasitic light sensitivity of the image sensor, so as to at least partially solve the above-mentioned technical problems.

[0004] In order to achieve the above-mentioned object, according to the first aspect of the present disclosure, a pixel unit is provided, comprising: a storage device, an isolation structure and a light shielding device. The storage device comprises a charge storage part and a storage gate located on the charge storage part; the isolation structure is arranged around the charge storage part, and a first gap is provided between the isolation structure and the charge storage part; the light shielding device is located on the isolation structure and at least covers a part of the first gap.

[0005] Optionally, the shading device is spaced apart from the storage gate, and the shading device covers a portion of the first gap.

[0006] Optionally, an extension direction of the shading device is the same as an extension direction of the first gap, and a length of the shading device is greater than or equal to a length of the first gap.

[0007] Optionally, the image sensor also includes a photoelectric device, and the photoelectric device and the storage device are located in a first enclosing area of ​​the isolation structure, the photoelectric device and the charge storage unit are arranged along a first direction, the first gap includes first sub-gaps located on opposite sides of the charge storage unit, two first sub-gaps are arranged along a second direction, and the second direction and the first direction intersect with each other; the shading device includes first sub-shading devices located on opposite sides of the charge storage unit in the second direction, and each of the first sub-shading devices covers a portion of the first sub-gap located on the same side.

[0008] Optionally, the pixel unit further includes a first transmission tube and a photoelectric device, the input electrode and the output electrode of the first transmission tube are electrically connected to the input electrode of the photoelectric device and the storage device respectively; the shading device is made of the same gate material as the first transmission tube and is interconnected.

[0009] Optionally, the shading device is in contact with the isolation structure, and the shading device is configured to input a negative voltage during a process in which the charge storage unit stores charges.

[0010] Optionally, the pixel unit further includes an optoelectronic device, a second gap is provided between the optoelectronic device and the isolation structure, and the light shielding device at least partially covers the second gap.

[0011] Optionally, an extension direction of the shading device is the same as an extension direction of the second gap, and the shading device includes an extension portion covering a portion of the second gap, and a length of the extension portion is greater than or equal to a length of the second gap.

[0012] Optionally, a width of the shading device at a position corresponding to the first gap is equal to a width of the shading device at a position corresponding to the second gap.

[0013] Optionally, the photoelectric device and the charge storage unit are arranged along a first direction, the first gap includes a first sub-gap located on opposite sides of the charge storage unit, two first sub-gaps are arranged along a second direction, the second direction and the first direction intersect with each other, and the second gap includes a second sub-gap located on opposite sides of the photoelectric device in the second direction; the shading device includes two first sub-shading devices and two second sub-shading devices, the two first sub-shading devices are located on opposite sides of the charge storage unit and respectively cover the first sub-gaps located on the same side, and the two second sub-shading devices are located on opposite sides of the photoelectric device and respectively cover the second sub-gaps located on the same side.

[0014] Optionally, the image sensor further comprises a first transmission tube and a photoelectric device, the input electrode and the output electrode of the first transmission tube being electrically connected to the input electrode of the photoelectric device and the storage device respectively; the shading device is electrically connected to the gate of the first transmission tube.

[0015] Optionally, the image sensor further includes: a photoelectric device, a first reset tube, a first transfer tube and a second transfer tube; the first reset tube is electrically connected to the photoelectric device, and the first reset tube is configured to reset the photoelectric device; the first transfer tube is electrically connected to the photoelectric device and the storage device, and the first transfer tube is configured to transfer the charge of the photoelectric device to the storage device; the second transfer tube is electrically connected to the storage device, and the second transfer tube is configured to output the charge of the storage device; wherein the isolation structure has a first enclosing area, and the first reset tube, the photoelectric device, the first transfer tube, the storage device and the second transfer tube are located in the first enclosing area.

[0016] Optionally, the image sensor also includes: a second reset tube, a source follower and a row gate tube; the second reset tube is electrically connected to the second transmission tube at a first node, and the second reset tube is configured to reset the first node; the source follower is electrically connected to the first node, and the source follower is configured to amplify the voltage of the first node; the row gate tube is electrically connected to the source follower, and the row gate tube is configured to output the amplified voltage; wherein the isolation structure has a second enclosing area, and the second reset tube, the source follower and the row gate tube are located in the second enclosing area.

[0017] According to a second aspect of the present disclosure, an image sensor is provided, comprising the pixel unit in the first aspect or the second aspect.

[0018] According to a third aspect of the present disclosure, a terminal device is provided, comprising the image sensor in the third aspect.

[0019] In the pixel unit provided in the embodiment of the present disclosure, since the shading device blocks the first gap, most of the ambient light originally incident on the charge storage part through the first gap is blocked by the shading device, thereby effectively reducing the amount of ambient light received by the charge storage part, and further effectively reducing the parasitic light sensitivity of the image sensor to ensure the final imaging quality of the image sensor.

[0020] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present disclosure, and those skilled in the art can obtain other drawings based on these drawings without creative work.

[0022] In order to more completely understand the present disclosure and its beneficial effects, the following description will be made in conjunction with the accompanying drawings, wherein the same drawing numbers represent the same parts in the following description.

[0023] Figure 1 is a structural schematic diagram of a pixel unit provided in some embodiments of the present disclosure;

[0024] Figure 2 yes Figure 1 Cross-sectional view along the A-A' direction;

[0025] Figure 3 yes Figure 1 Cross-sectional view along the B-B' direction;

[0026] Figure 4 is a structural schematic diagram of a pixel unit provided in some other embodiments of the present disclosure;

[0027] Figure 5 is a structural schematic diagram of a pixel unit provided by some other embodiments of the present disclosure;

[0028] Figure 6 is a structural schematic diagram of a pixel unit provided by some other embodiments of the present disclosure;

[0029] Figure 7 is a circuit structure diagram of a pixel circuit provided in some embodiments of the present disclosure;

[0030] Figure 8 It is a simulation diagram of an image sensor in the related art and an image sensor provided by some embodiments of the present disclosure;

[0031] Fig. 9 It is a simulation diagram of a part of the position of an image sensor in the related art;

[0032] Fig.10 is a simulation diagram of a partial position of an image sensor provided by some embodiments of the present disclosure;

[0033] Fig.11 is a dark current curve diagram of an image sensor in the related art and an image sensor provided by some embodiments of the present disclosure;

[0034] Fig.12 It is a schematic diagram of the structure of an image sensor provided by some embodiments of the present disclosure.

[0035] Description of reference numerals:

[0036] 100, image sensor; 101, pixel unit; 1001, pixel unit array; 102, row selection logic circuit; 103, readout circuit; 104, column selection logic circuit; 105, controller; 11, isolation structure; 110, gate of the first transmission tube; 111, gate of the second reset tube; 112, gate of the source follower; 113, gate of the row selection tube; 114, gate oxide layer; 12A, first enclosing area; 12B, second enclosing area; 13, output electrode of the first reset tube; 14, gate of the first reset tube; 15, optoelectronic device; 16A, first floating diffusion; 16B, second floating diffusion; 17, gate of the second transmission tube; 18, charge storage unit; 19, storage gate;

[0037] 21. shading device; 211. first sub-shading device; 212. second sub-shading device; 22. ambient light;

[0038] 31. First reset tube; 32. Photodiode; 33. First transmission tube; 34. Storage device; 35. Second transmission tube; 36. First node; 37. Row selection tube; 38. Source follower; 39. Second reset tube. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present disclosure will be described clearly and completely below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present disclosure.

[0040] The present disclosure provides a pixel unit. Figures 1 to 3 The pixel unit 101 includes a storage device 34, which includes a charge storage unit 18 and a storage gate 19. The storage device 34 can be turned on and off by controlling the voltage of the storage gate 19. When the storage device 34 is turned on, the storage device 34 can store charges.

[0041] The pixel unit 101 further includes an isolation structure 11 and a shading device 21 . The isolation structure 11 is arranged around the charge storage portion 18 . A first gap K is provided between the isolation structure 11 and the charge storage portion 18 . The shading device 21 at least covers a portion of the first gap K.

[0042] For the pixel unit 101 provided in the embodiment of the present disclosure, the first gap K is shielded by setting a shading device 21, such as Figure 3 As shown, most of the ambient light 22 originally incident on the charge storage unit 18 through the first gap K is blocked by the shading device 21, thereby effectively reducing the amount of ambient light received by the charge storage unit 18, and further effectively reducing the parasitic light sensitivity of the image sensor 100 including the pixel unit 101, so as to ensure the final imaging quality of the image sensor 100.

[0043] The shading device 21 can block the light in at least one of a reflection mode and an absorption mode. The blocking mode of the light by the shading device 21 can be adjusted according to the material of the shading device 21. For example, the shading device 21 can be made of a metal material or a polysilicon material, which is not limited in the present disclosure.

[0044] It is worth noting that “the shading device 21 is located on the isolation structure 11”, which means that the shading device 21 is manufactured on the isolation structure 11 and directly contacts the isolation structure 11, or that an intermediate partition layer is provided between the shading device 21 and the isolation structure 11, and the shading device 21 is provided on the intermediate partition layer and contacts the intermediate partition layer.

[0045] In some examples, the first gap K is a continuous and unobstructed gap, that is, when there is no obstruction of other devices between the isolation structure 11 and the charge storage unit 18, the isolation structure 11 and the charge storage unit 18 have the above-mentioned first gap K.

[0046] In some embodiments, the light shielding device 21 may completely cover the first gap K.

[0047] With this arrangement, the first gap K is completely covered by the shading device 21 , which can effectively prevent the ambient light 22 from entering the charge storage unit 18 through the first gap K and causing adverse effects on the storage device 34 , thereby effectively improving the imaging quality of the image sensor 100 .

[0048] In some examples, an intermediate spacer is provided between the light shielding device 21 and the isolation structure 11, and the light shielding device 21 is disposed on the intermediate spacer. In this way, the light shielding device 21 can be prevented from contacting the layout position of other structures in the pixel unit 101 (for example, the storage gate 19 of the storage device 34) through the spacing of the intermediate spacer, thereby preventing the performance of the image sensor 100 from being reduced.

[0049] In some embodiments, Figure 1 and Figure 3 As shown, the shading device 21 can cover a portion of the first gap K.

[0050] With this arrangement, the covering range of the shading device 21 can be adjusted according to the layout positions of other structures in the pixel unit 101 (such as the storage gate 19 of the storage device 34), thereby avoiding adverse effects on the performance of the image sensor 100 due to coverage or contact between the shading device 21 and other devices.

[0051] In some examples, the light shielding device 21 and the storage gate 19 are located in the same layer and are spaced apart, so that an electrical connection can be avoided between the light shielding device 21 and the storage gate 19. Since the storage gate 19 needs to input positive voltage and negative voltage at different stages, if the light shielding device 21 is in contact with the storage gate 19, it is easy to cause the light shielding device 21 to synchronously input positive voltage or negative voltage at the stage when the storage gate 19 inputs positive voltage or negative voltage, thereby affecting the hole concentration of the side wall of the isolation structure 11, which may have an adverse effect on the performance of the image sensor 100.

[0052] In some embodiments, Figure 1 As shown, the extension direction of the shading device 21 is the same as the extension direction of the first gap K. In this way, according to the extension of the first gap K, the shading device 21 can be used to form a good covering effect on the first gap K, thereby reducing the amount of ambient light received by the charge storage unit 18, thereby improving the imaging effect of the image sensor 100.

[0053] In some examples, the length D1 of the shading device 21 (ie, the dimension of the shading device 21 in its extending direction) is greater than or equal to the length D2 of the first gap K (ie, the dimension of the first gap K in its extending direction).

[0054] By setting the length D1 of the shading device 21 to exceed the length D2 of the first gap K, the shading device 21 can form a good covering effect on the first gap K, thereby further reducing the amount of ambient light received by the charge storage unit 18 .

[0055] As an implementation manner, the length D1 of the light shielding device 21 may be equal to the length D2 of the first gap K.

[0056] As another implementation manner, the length D1 of the shading device 21 may be greater than the length D2 of the first gap K.

[0057] In some examples, the shading device 21 and the first gap K both extend along the first direction X, and in the second direction Y, the shading device 21 covers the first gap K, wherein the second direction Y is perpendicular to the first direction X.

[0058] In this way, the shading device 21 can effectively surround the first gap K in the first direction X, thereby facilitating the reduction of the amount of ambient light received by the charge storage unit 18. When the length D1 of the shading device 21 is greater than the length D2 of the first gap K, the shading device 21 can block the ambient light incident on the charge storage unit 18 from the peripheral area of ​​the charge storage unit 18, thereby further reducing the amount of ambient light received by the charge storage unit 18, and thus improving the imaging effect of the image sensor 100.

[0059] In some embodiments, Figure 1 and Figure 4 As shown, the pixel unit 101 further includes an optoelectronic device 15 , and the optoelectronic device 15 and the memory device 34 are located in the first enclosing region 12A of the isolation structure 11 .

[0060] like Figure 4 As shown, the photoelectric device 15 and the charge storage portion 18 are arranged along the first direction X, the first gap K includes first sub-gaps K1 located on opposite sides of the charge storage portion 18, and the two first sub-gaps K1 are arranged along the second direction Y, and the second direction Y and the first direction X intersect each other. For example, the second direction Y and the first direction X may be perpendicular to each other.

[0061] The light-shielding device 21 includes first sub-light-shielding devices 211 located at two opposite sides of the charge storage portion 18 in the second direction Y, and each first sub-light-shielding device 211 covers a portion of the first sub-gap K1 located at the same side.

[0062] In this way, by partially covering the first sub-gaps K1 on the opposite sides of the charge storage unit 18 , a good light shielding effect can be achieved, thereby reducing the amount of ambient light received by the charge storage unit 18 , thereby improving the imaging effect of the image sensor 100 .

[0063] In some examples, the first sub-gaps K1 located on opposite sides of the charge storage unit 18 have the same shape and size, and the two first sub-light shielding devices 211 also have the same shape and size. This helps to ensure that the light shielding device 21 forms a good light shielding effect on the first gap K, thereby reducing the amount of ambient light received by the charge storage unit 18, thereby improving the imaging effect of the image sensor 100.

[0064] As an implementation manner, the two first sub-light-shielding devices 211 may be parallel to each other. For example, the two first sub-light-shielding devices 211 both extend along the first direction X.

[0065] When the two first sub-shading devices 211 extend along the first direction X, the two first sub-shading devices 211 can be symmetrical with each other about a symmetry axis parallel to the first direction X. In addition, the two first sub-gaps K1 can also be symmetrical with each other about the symmetry axis. In this way, while ensuring that the shading device 21 forms a good shading effect on the first gap K, it is also beneficial to the patterning of the shading device 21.

[0066] In some embodiments, Figure 6 As shown, in addition to the photoelectric device 15, the pixel unit 101 further includes a first transmission tube 33, the input electrode of the first transmission tube 33 is electrically connected to the photoelectric device 15, and the output electrode of the first transmission tube 33 is electrically connected to the input electrode of the storage device 34. When the first transmission tube 33 is turned on, the charge from the photoelectric device 15 can be transmitted to the charge storage unit 18 of the storage device 34 through the first transmission tube 33 for storage.

[0067] The light shielding device 21 and the gate 110 of the first transmission tube 33 are made of the same material and are connected to each other. In this case, the light shielding device 21 and the gate 110 of the first transmission tube 33 can be an integrated structure, which not only serves as the gate 110 of the first transmission tube 33, but can also be reused as the light shielding device 21. This is conducive to simplifying the structure in the pixel unit 101, thereby reducing the manufacturing cost of the image sensor 100.

[0068] In some embodiments, Figure 1 , Figures 4 to 6 As shown, the shading device 21 is in contact with the isolation structure 11 , and the shading device 21 is configured to input a negative voltage during the process of the charge storage portion 18 storing charges.

[0069] Since the distances between the charge storage part 18 and the photoelectric device 15 and the isolation structure 11 are relatively close, when the charge storage part 18 and the photoelectric device 15 are reset, the boundaries of the PN junction depletion regions of the charge storage part 18 and the photoelectric device 15 will extend to the sidewalls of the isolation structure 11. The rate at which the sidewall defects are generated in the depletion state is high, causing the generated electrons to drift into the charge storage part 18 and the photoelectric device 15, thereby forming a relatively large dark current, which affects the imaging effect of the image sensor 100. Since the light shielding device 21 in this embodiment can input a negative voltage, the potential at the sidewall of the isolation structure 11 can be reduced. The lower potential will attract holes to enrich toward the sidewall surface (hereinafter referred to as the sidewall) of the isolation structure 11, so that the hole concentration of the sidewall of the isolation structure 11 increases, thereby passivating the defect state of the sidewall of the isolation structure 11, reducing the rate of generation of dark current at the sidewall of the isolation structure 11, thereby reducing the dark current shot noise, and ultimately improving the imaging effect of the image sensor 100. Furthermore, the image sensor 100 has low dark current and low parasitic light sensitivity and can be used as a global shutter image sensor.

[0070] It can be understood that according to the SRH (Shockley Read Hall) theory, the dark current generation rate G at the defect can be expressed by the following relationship:

[0071]

[0072] Where n and p are the electron concentration and hole concentration at the defect, respectively. i is the intrinsic carrier concentration, N t is the defect state density, r n and r p are the defect capture coefficients respectively. From this relationship, it can be seen that increasing the hole concentration p at the defect can reduce the defect generation rate G. The hole concentration p at the defect is closely related to the potential V at the location, and the relationship can be expressed by the following formula:

[0073]

[0074] Among them, P n0 is the equilibrium hole concentration in the n-type region of the PN junction, V D is the equilibrium barrier height of the PN junction, q is the elementary charge, k is a constant, and T is the temperature. From this relationship, we can see that the more negative the potential V is, the larger p is. Combined with the dark current generation rate relationship, we can see that the more negative the potential at the defect is, the lower the defect generation rate is.

[0075] Therefore, the embodiment of the present disclosure can reduce the electric potential at the side wall of the isolation structure 11 by setting a shading device 21 above the side wall of the isolation structure 11 and applying a turn-off voltage lower than 0V to the shading device 21, thereby increasing the hole concentration at the isolation structure, and ultimately reducing the generation rate of defects at the side wall of the isolation structure 11, reducing dark current, and further reducing dark current shot noise.

[0076] In some examples, the negative voltage input into the light shielding device 21 may be less than 0V and greater than -2V.

[0077] In some embodiments, Figure 5 As shown, when the pixel unit 101 includes the optoelectronic device 15 , a second gap P is provided between the optoelectronic device 15 and the isolation structure 11 , and a portion of the second gap P is covered by the light shielding device 21 .

[0078] Ambient light usually propagates toward the charge storage portion 18 from multiple directions, and due to the existence of the second gap P between the optoelectronic device 15 and the isolation structure 11, the ambient light is emitted toward the charge storage portion 18 through the second gap P. Therefore, by providing the shading device 21 to also cover part of the second gap P, the amount of light received by the charge storage portion 18 can be further reduced, thereby improving the imaging effect of the image sensor 100.

[0079] In addition, since the contact range between the isolation structure 11 and the shading device 21 increases, when a negative voltage is input to the shading device 21 during the process of storing charges in the charge storage unit 18, the amount of holes attracted by the side walls of the isolation structure 11 increases, which is beneficial to enhancing the passivation effect of the defect states on the side walls of the isolation structure 11, thereby reducing the rate of dark current generation at the side walls of the isolation structure 11.

[0080] In some examples, the second gap P is a continuous and unobstructed gap, that is, when there is no obstruction of other devices between the isolation structure 11 and the optoelectronic device 15 , the isolation structure 11 and the optoelectronic device 15 have the second gap P mentioned above.

[0081] As a way to achieve this, Figure 5 As shown, the shading device 21 includes a first sub-shading device 211 covering part of the first gap K and a second sub-shading device 212 covering part of the second gap P. The first sub-shading device 211 and the second sub-shading device 212 can be arranged continuously or at intervals.

[0082] When the first sub-light-shielding device 211 and the second sub-light-shielding device 212 are arranged at an interval, the first sub-light-shielding device 211 and the second sub-light-shielding device 212 are disconnected, and the first sub-light-shielding device 211 and the second sub-light-shielding device 212 can respectively input negative voltages during the process of the charge storage unit 18 storing charges.

[0083] In the case where the first sub-shading device 211 and the second sub-shading device 212 are arranged continuously, as shown in FIG. Figure 5 As shown, the extension direction of the shading device 21 is the same as the extension direction of the second gap P, and the shading device 21 includes an extension portion that partially covers the second gap P (i.e., the above-mentioned second sub-shading device 212), and the length D4 of the extension portion (i.e., the size of the extension portion in the extension direction of the shading device 21) is greater than or equal to the length D3 of the second gap P (i.e., the size of the second gap P in its extension direction).

[0084] By setting the length of the extension portion to be greater than or equal to the length of the second gap P, on the one hand, the shading device 21 can form a good covering effect on the second gap P, thereby further reducing the amount of ambient light received by the charge storage unit 18; on the other hand, the contact range between the isolation structure 11 and the shading device 21 is increased. When the shading device 21 inputs a negative voltage during the process of storing charges in the charge storage unit 18, the amount of holes attracted by the side wall of the isolation structure 11 increases, which is beneficial to enhancing the passivation effect of the defect state on the side wall of the isolation structure 11, thereby reducing the generation rate of dark current at the side wall of the isolation structure 11.

[0085] It should be noted that there is a gap between the photoelectric device 15 and the charge storage portion 18 , and the first sub-light-shielding device 211 may extend to the position of the charge storage portion 18 , and then continue to extend to form the above-mentioned extension portion.

[0086] In some embodiments, Figure 5 As shown, the width D5 of the shading device 21 at the position corresponding to the first gap K is equal to the width D6 of the shading device 21 at the position corresponding to the second gap P. That is, the width of the first sub-shading device 211 of the shading device 21 is equal to the width of the second sub-shading device 212. The width of the shading device 21 refers to the size of the shading device 21 perpendicular to its extension direction. For example, the extension direction of the shading device 21 is toward the first direction X, and the width of the shading device 21 is its size in the second direction Y.

[0087] Such an arrangement makes the shading device 21 a strip structure of equal width, which can ensure its structural stability on the one hand, and is also conducive to achieving a relatively uniform shielding effect for the first gap K and the second gap P on the other hand.

[0088] In some examples, the first gap K and the second gap P are equal in size.

[0089] In some embodiments, Figure 5As shown, the optoelectronic device 15 and the charge storage portion 18 are arranged along the first direction X, the first gap K includes first sub-gaps K1 located on opposite sides of the charge storage portion 18, and the two first sub-gaps K1 are arranged along the second direction Y, and the second direction Y and the first direction X intersect each other. The second gap P includes second sub-gaps P1 located on opposite sides of the optoelectronic device 15 in the second direction Y.

[0090] The shading device 21 includes two first sub-shading devices 211 and two second sub-shading devices 212. The two first sub-shading devices 211 are located on opposite sides of the charge storage part 18 and respectively cover a portion of the first sub-gap K1 located on the same side as the first sub-shading devices 211. The two second sub-shading devices 212 are located on opposite sides of the photoelectric device 15 and respectively cover a portion of the second sub-gap P1 located on the same side as the second sub-shading devices 212.

[0091] In this way, by partially blocking the first sub-gap K1 located on the opposite sides of the charge storage unit 18 and the second sub-gap P1 located on the opposite sides of the photoelectric device 15, a good shading effect can be achieved, reducing the amount of ambient light received by the charge storage unit 18, thereby improving the imaging effect of the image sensor 100.

[0092] As an implementation manner, the two second sub-light-shielding devices 212 may be parallel to each other. For example, the two second sub-light-shielding devices 212 both extend along the first direction X.

[0093] When the two second sub-shading devices 212 extend along the first direction X, the two second sub-shading devices 212 can be symmetrical with each other about a symmetry axis parallel to the first direction X. In addition, the two first sub-gaps K1 and the two second sub-gaps P1 can also be symmetrical with each other about the symmetry axis. In this way, while ensuring that the shading device 21 forms a good shading effect on the first gap K, it is also beneficial to the patterning of the shading device 21.

[0094] It is worth noting that, for the pixel unit 101 provided in the embodiment of the present disclosure, when the shading device 21 inputs a negative voltage during the process of storing charges in the charge storage unit 18, the shading device 21 can also be used only to increase the hole concentration of the sidewall of the isolation structure 11, thereby reducing the dark current; and the shading device 21 does not play a role in blocking light to reduce parasitic light sensitivity. In this case, the shading device 21 can be named by other names, for example, it can be called a passivation device. In addition, the passivation device is at least partially disposed on the isolation structure 11 and in contact with the isolation structure 11.

[0095] In this case, if Figures 1 to 5As shown, the pixel unit 101 may include: a storage device 34, an isolation structure 11 and a passivation device; the storage device 34 includes a charge storage part 18, the isolation structure 11 is arranged around the charge storage part 18, the passivation device is arranged on the isolation structure 11 and in contact with the isolation structure 11, and the passivation device is configured to input a negative voltage during the process of storing charges in the charge storage part 18.

[0096] Since the distances between the charge storage unit 18 and the photoelectric device 15 and the isolation structure 11 are relatively close, when the charge storage unit 18 and the photoelectric device 15 are reset, the boundaries of the PN junction depletion regions of the charge storage unit 18 and the photoelectric device 15 will extend to the sidewalls of the isolation structure 11. The rate at which the sidewall defects are generated in the depletion state is large, causing the generated electrons to drift into the charge storage unit 18 and the photoelectric device 15, thereby forming a large dark current, which affects the imaging effect of the image sensor. Since a passivation device capable of inputting a negative voltage is provided in this embodiment, and the passivation device is in contact with the isolation structure 11, the potential at the sidewall of the isolation structure 11 can be reduced. The lower potential will attract holes to enrich toward the sidewall surface (hereinafter referred to as the sidewall) of the isolation structure 11, so that the hole concentration of the sidewall of the isolation structure 11 increases, thereby passivating the defect state of the sidewall of the isolation structure 11, reducing the rate of generation of dark current at the sidewall of the isolation structure 11, thereby reducing dark current shot noise, and ultimately improving the imaging effect of the image sensor.

[0097] In some embodiments, Figure 6 and Figure 7 As shown, in addition to the photoelectric device 15, the pixel unit 101 further includes a first transmission tube 33, the input electrode of the first transmission tube 33 is electrically connected to the photoelectric device 15, and the output electrode of the first transmission tube 33 is electrically connected to the input electrode of the storage device 34. When the first transmission tube 33 is turned on, the charge from the photoelectric device 15 can be transmitted to the charge storage unit 18 of the storage device 34 through the first transmission tube 33 for storage.

[0098] The light shielding device 21 is electrically connected to the gate 110 of the first transmission tube 33. In this way, when a negative voltage is input to the gate 110 of the first transmission tube 33, the first transmission tube 33 is in a conducting state, and the charge storage unit 18 stores the charge from the photoelectric device 15. Since the light shielding device 21 is electrically connected to the gate 110 of the first transmission tube 33, the potential at the side wall of the isolation structure 11 is reduced, and the hole concentration at the isolation structure 11 is increased, so that the defect state of the side wall of the isolation structure 11 can be passivated, the generation rate of the dark current at the side wall of the isolation structure 11 is reduced, and the dark current shot noise is reduced, and finally the imaging effect of the image sensor 100 is improved.

[0099] In some examples, the shading device 21 and the gate 110 of the first transmission tube 33 can be an integrated structure, so that the integrated structure not only serves as the gate 110 of the first transmission tube 33, but can also be reused as the shading device 21. At this time, the integrated structure is directly electrically connected to the signal input line to input a negative voltage into the shading device 21, which is beneficial to simplifying the device structure in the image sensor 100, thereby reducing the manufacturing cost of the image sensor 100.

[0100] In some embodiments, Figure 1 , Figures 4 to 7 As shown, in addition to the storage device 34 , the pixel unit 101 further includes: a photoelectric device 15 , a first reset tube 31 , a first transmission tube 33 and a second transmission tube 35 .

[0101] Among them, the first reset tube 31 is electrically connected to the photoelectric device 15, and the first reset tube 31 is configured to reset the photoelectric device 15; the first transmission tube 33 is electrically connected to the photoelectric device 15 and the storage device 34, and the first transmission tube 33 is configured to transfer the charge of the photoelectric device 15 to the storage device 34; the second transmission tube 35 is electrically connected to the storage device 34, and the second transmission tube 35 is configured to output the charge of the storage device 34.

[0102] The isolation structure 11 has a first enclosing region 12A. The first reset transistor 31 , the photoelectric device 15 , the first transmission transistor 33 , the storage device 34 and the second transmission transistor 35 are located in the first enclosing region 12A.

[0103] Such an arrangement enables the first reset tube 31 , the optoelectronic device 15 , the first transmission tube 33 , the storage device 34 and the second transmission tube 35 to be well arranged, so as to improve the structural compactness of the pixel unit 101 and further improve the working performance of the image sensor 100 .

[0104] In some examples, the input electrode of the first reset tube 31 is electrically connected to the photoelectric device 15, and the output electrode of the first reset tube 31 is electrically connected to the first voltage terminal V AB The gate of the first reset transistor 31 is electrically connected to the first reset signal line GS. When the first reset signal line GS inputs a high voltage to the gate of the first reset transistor 31, the first reset transistor 31 is turned on and resets the photoelectric device 15, so that the charge in the photoelectric device 15 is cleared.

[0105] The input electrode of the first transmission tube 33 is electrically connected to the photoelectric device 15, the output electrode of the first transmission tube 33 is electrically connected to the input electrode of the storage device 34, and the gate electrode of the first transmission tube 33 is electrically connected to the first transmission driving line TX1. When the first transmission driving line TX1 inputs a high voltage to the gate electrode of the first transmission tube 33, the first transmission tube 33 is turned on, so that the charge in the photoelectric device 15 is transferred to the charge storage unit 18 of the storage device 34 for storage.

[0106] The storage gate 19 of the storage device 34 is electrically connected to the storage device driving line TXS. When the storage device driving line TXS outputs a high voltage to the storage gate 19 of the storage device 34, the storage device 34 is turned on, so that the charge storage unit 18 can store charges.

[0107] The input electrode of the second transmission tube 35 is electrically connected to the output electrode of the storage device 34, the output electrode of the second transmission tube 35 is connected to the first node 36, and the gate of the second transmission tube 35 is electrically connected to the second transmission driving line TX2. When the second transmission driving line TX2 inputs a high voltage to the gate of the second transmission tube 35, the second transmission tube 35 is turned on, so that the charge stored in the storage device 34 is transferred to the first node 36.

[0108] In some embodiments, Figure 1 , Figures 4 to 7 As shown, the pixel unit 101 further includes: a second reset tube 39 , a source follower 38 and a row gate tube 37 .

[0109] Among them, the second reset tube 39 is electrically connected to the second transmission tube 35 at the first node 36, and the second reset tube 39 is configured to reset the first node 36; the source follower 38 is electrically connected to the first node 36, and the source follower 38 is configured to amplify the voltage of the first node 36; the row selection tube 37 is electrically connected to the source follower 38, and the row selection tube 37 is configured to output the amplified voltage.

[0110] The isolation structure 11 has a second surrounding area 12B, and the second reset transistor 39, the source follower 38 and the row gate transistor 37 are located in the second surrounding area 12B.

[0111] Such an arrangement can make the second reset tube 39 , the source follower 38 and the row gate tube 37 well arranged, so as to improve the structural compactness of the pixel unit 101 , and further improve the working performance of the image sensor 100 .

[0112] The input electrode of the second reset tube 39 is electrically connected to the first node 36, and the output electrode of the second reset tube 39 is electrically connected to the power line V ddThe gate of the second reset tube 39 is electrically connected to the second reset signal line RST; when the second reset signal line RST inputs a high voltage to the gate of the second reset tube 39, the second reset tube 39 is turned on, thereby resetting the first node 36.

[0113] The input terminal of the source follower 38 is connected to the power line V dd The output of the source follower 38 is electrically connected to the input of the row selection tube 37; the gate of the source follower 38 is electrically connected to the first node 36; when the voltage at the first node 36 is at a high potential, it can be amplified through the source follower 38.

[0114] The output terminal of the row gate tube 37 is connected to the column selection line V out The gate of the row gate transistor 37 is electrically connected to the row gate signal line SEL. When the row gate signal line SEL inputs a high voltage to the gate of the row gate transistor 37, the row gate signal line SEL is in an open state, thereby outputting the voltage signal amplified by the source follower 38 to the external circuit.

[0115] In some examples, optoelectronic device 15 may be a photodiode 32 .

[0116] In some embodiments, the photoelectric device 15 , the first reset tube 31 , the first transfer tube 33 , the storage device 34 , the second transfer tube 35 , the second reset tube 39 , the source follower 38 and the row gate tube 37 may together constitute a pixel circuit of the pixel unit 101 .

[0117] The working process of the pixel circuit includes the following stages.

[0118] (1) Photoelectric device reset stage: a high voltage is input to the gate of the first reset tube 31, and the gate of the first transmission tube 33 is kept at a low voltage; in this stage, the photoelectric device 15 is reset, and the charge in the photoelectric device 15 is cleared.

[0119] (2) Photoelectric device exposure stage: After the photoelectric device reset stage is completed, a low voltage is input to the gate of the first reset tube 31. At this time, the photoelectric device 15 starts to be exposed, receives external light signals and converts them into photogenerated charges.

[0120] (3) Charge storage unit reset stage: After the exposure stage of the photoelectric device is completed, a high voltage is input to the gate of the second reset tube 39 and the gate of the second transfer tube 35. At this time, the charge storage unit 18 of the storage device 34 is reset and the charge in the charge storage unit 18 is cleared.

[0121] (4) Charge transfer stage: After the charge storage unit reset stage is completed, a low voltage is input to the gate of the second reset tube 39 and the gate of the second transfer tube 35, and then a high voltage is input to the gate of the first transfer tube 33 and the storage gate 19 of the storage device 34, so that the photogenerated charges in the photoelectric device 15 are transferred to the charge storage unit 18 for storage.

[0122] (5) Charge storage stage: After the charge transfer stage is completed, a low voltage (ie, a negative voltage) is input to the gate of the first transmission transistor 33 and the storage gate 19 of the storage device 34, and the charge storage stage is entered.

[0123] (6) Charge readout stage: After the charge storage stage is completed, a high voltage is input to the gate of the second reset transistor 39 to reset the first node 36; after the reset is completed, a low voltage is input to the gate of the second reset transistor 39, and then a high voltage is input to the gate of the row selection transistor 37, so that the reset signal of the first node 36 is output to the column selection line V through the gate of the source follower 38. out After the reset signal of the first node 36 is output, a high voltage can be input to the gate of the second transmission tube 35 to transfer the photogenerated charge of the charge storage unit 18 to the first node 36 and convert it into a photogenerated voltage signal. The voltage of the photogenerated voltage signal is then amplified by the source follower 38 and output to the column selection line V by the row gate tube 37. out and finally output to the external circuit.

[0124] In some examples, during the charge storage phase, the gate of the first transfer transistor 33 , the gate of the second transfer transistor 35 , and the storage gate 19 of the storage device 34 all maintain a potential less than 0 to reduce dark current.

[0125] In some examples, during the charge storage stage, the low potential of the storage gate 19 may be higher than the low potential of the gate of the first transfer tube 33 , so that the charge storage unit 18 can store more photogenerated charges transmitted from the photoelectric device 15 .

[0126] Some embodiments of the present disclosure provide an image sensor 100 , which includes the pixel unit 101 described in any embodiment of the present disclosure.

[0127] Since the image sensor 100 includes the pixel unit 101 , it has all the technical effects of the pixel unit 101 .

[0128] In some embodiments, Fig.12As shown, the image sensor 100 may include a plurality of pixel units 101. The plurality of pixel units 101 may be arranged in an array to form a pixel unit array 1001. For example, the plurality of pixel units 101 may be arranged along a row direction to form a pixel unit row, and the plurality of pixel unit rows may be arranged along a column direction, wherein an angle exists between the row direction and the column direction. The angle may be, for example, 90°.

[0129] In order to further illustrate the effects of the image sensor 100 provided by the embodiment of the present disclosure, the inventors will include the following Figure 6 The image sensor 100 of the pixel unit 101 shown in the figure is simulated with the image sensor 100' in the related art, and the following is obtained: Figures 8 to 10 The simulation diagram shown in FIG. Figure 8 (a) is the dark current generation rate of the longitudinal section of the image sensor 100' in the related art, Figure 8 (c) Figure 8 (a) The enlarged image of the dotted box. Figure 8 (b) is a simulation diagram of the dark current generation rate of the longitudinal section of the image sensor 100 provided by the embodiment of the present disclosure, Figure 8 (d) Figure 8 (b) Enlarged view of the dashed box.

[0130] As for the simulation results of the image sensor 100', after the charge storage unit is reset, the charge storage unit depletion region (the area surrounded by the black solid line) has expanded to the side wall of the isolation structure (such as Figure 8 (c) shows that the maximum dark current generation rate on the sidewall of the isolation structure reaches 1e17 cm -3 s -1 As for the simulation results of the image sensor 100, when the light shielding device is used to cover the side wall of the isolation structure 11 and a negative voltage of -1V is applied to it, the depletion region of the charge storage part (the area surrounded by the black solid line) will be effectively shrunk and will not directly contact the side wall of the isolation structure 11 (such as Figure 8 (d)), thereby reducing the dark current generation rate of the side wall of the isolation structure 11 to 1e9cm -3 s -1 .

[0131] Fig. 9 (a) Figure 8 (c) is a potential simulation diagram of a longitudinal section along the dotted line AA' of the isolation structure sidewall. Fig. 9 (b) Figure 8 (c) is a simulation diagram of the hole concentration along the dashed line AA' of the isolation structure sidewall. Fig. 9 (c) Figure 8 (c) is a simulation diagram of the dark current generation rate along the dashed line AA' of the isolation structure sidewall; Fig.10 (a) Figure 8 (d) is a potential simulation diagram of a longitudinal section along the dotted line AA' of the isolation structure sidewall. Fig.10 (b) Figure 8 (d) is a simulation diagram of the hole concentration along the dashed line AA' of the isolation structure sidewall. Fig.10 (c) Figure 8 (d) is a simulation diagram of the dark current generation rate along the AA' dashed line of the isolation structure sidewall. Fig. 9 and Fig.10 It can be seen that compared with the image sensor 100', the image sensor 100 provided in the embodiment of the present disclosure uses a light shielding device to cover the side wall of the isolation structure 11 and applies a negative voltage thereto, which can significantly reduce the potential of the side wall surface of the isolation structure from 0.05V to -0.49V, thereby reducing the hole concentration from 10 9 cm -3 Significantly increased to 10 18 cm -3 , thereby reducing the dark current generation rate from 1e17cm -3s-1 Reduced to 1e9cm -3s-1 .

[0132] Fig.11 1 is a dark current curve diagram of the charge storage unit of the image sensor 100 and the image sensor 100 ′, as shown in FIG. Fig.11 As shown, compared with the image sensor 100', the image sensor 100 provided by the embodiment of the present disclosure can reduce the dark current of the charge storage unit from 120e- / s to 0.6e- / s, which is reduced by 200 times. Therefore, the image sensor 100 provided by the embodiment of the present disclosure can significantly reduce the dark current, thereby improving its imaging effect.

[0133] In some examples, such as Fig.12 As shown, the image sensor 100 further includes a row selection logic circuit 102, a readout circuit 103, a column selection logic circuit 104, and a controller 105. The row selection logic circuit 102 is electrically connected to the pixel unit 101 in each pixel unit row in the pixel unit array 1001, the readout circuit 103 is electrically connected to the pixel unit 101 in each pixel unit column in the pixel unit array 1001, and the readout circuit 103 is also electrically connected to the column selection logic circuit 104; the controller 105 is electrically connected to the row selection logic circuit 102, the readout circuit 103, and the column selection logic circuit 104, respectively.

[0134] In order to more clearly describe the structure of the pixel unit 101, Figures 1 to 3 The following embodiments further describe the pixel unit 101.

[0135] Two adjacent pixel units 101 can be separated by an isolation structure 11 to avoid interference between the two adjacent pixel units 101. The isolation structure 11 can be a shallow trench isolation structure or a deep trench isolation structure, which is mainly used to isolate the leakage of electricity and light between the pixel units 101.

[0136] By way of example, the material of the isolation structure 11 may include silicon oxide.

[0137] In each pixel unit, the isolation structure 11 may have a first enclosing area 12A and a second enclosing area 12B, wherein a first silicon active portion may be provided in the first enclosing area 12A, and the first silicon active portion is used to carry the device located in the first enclosing area 12A; a second silicon active portion may be provided in the second enclosing area 12B, and the second silicon active portion is used to carry the device located in the second enclosing area 12B. The first silicon active portion and the second silicon active portion may be of the same conductivity type or of different conductivity types, and the embodiments of the present disclosure do not limit them. For example, the first silicon active portion and the second silicon active portion are both N-type silicon or P-type silicon, in which case, the first silicon active portion and the second silicon active portion are of the same conductivity type. For another example, the first silicon active portion is one of N-type silicon or P-type silicon, and the second silicon active portion is the other of N-type silicon or P-type silicon, in which case, the first silicon active portion and the second silicon active portion are of different conductivity types. Among them, the doping element in the N-type silicon is, for example, phosphorus or arsenic, and the doping element in the P-type silicon is, for example, boron.

[0138] In some examples, the first silicon active portion and the second silicon active portion are of the same conductivity type. For ease of description, the conductivity type of the first silicon active portion and the second silicon active portion is referred to as the first conductivity type hereinafter.

[0139] In some examples, a gate oxide layer 114 is disposed above the isolation structure 11 and at the location of the first surrounding region 12A.

[0140] In some examples, the output electrode 13 of the first reset transistor 31 is disposed in the first enclosing area 12A. As an implementation, the output electrode 13 of the first reset transistor 31 may contact the side wall of the isolation structure 11 .

[0141] In some examples, the first reset tube 31 may be of the second conductivity type, that is, the conductivity type of the first reset tube 31 is different from the conductivity type of the first silicon active portion. For example, when the first reset tube 31 is an N-type metal oxide semiconductor field effect transistor (MOSFET), the first silicon active portion is P-type silicon. For another example, when the first reset tube 31 is a P-type MOSFET, the first silicon active portion is N-type silicon.

[0142] It is worth noting that the first silicon active portion can be used as the substrate of the first reset transistor 31 , and the conductivity and response speed of the first reset transistor 31 can be effectively adjusted by changing the concentration of the doped elements in the first silicon active portion.

[0143] The gate 14 of the first reset tube 31 is disposed on the first silicon active portion and coupled with the output electrode 13 of the first reset tube 31. The gate 14 of the first reset tube 31 can be located at the front side, the rear side, the left side or the right side of the output electrode 13 of the first reset tube 31, as long as the gate 14 of the first reset tube 31 can be coupled with the output electrode 13 of the first reset tube 31.

[0144] In some examples, the photoelectric device 15 is disposed in the first enclosing area 12A, and the photoelectric device 15 is coupled to the gate 14 of the first reset transistor 31. The photoelectric device 15 can receive external light signals and convert them into photogenerated charges. For example, the photoelectric device 15 can be a surface pinned photodiode.

[0145] In some examples, the storage gate 19 and the charge storage portion 18 are both disposed in the first enclosed area 12A and the storage gate 19 is located above the charge storage portion 18. The charge storage portion 18 can be located at the front side, the rear side, the left side or the right side of the optoelectronic device 15, and the present disclosure does not limit the positional relationship between the two. When a high voltage is input to the storage gate 19, the photogenerated charges in the optoelectronic device 15 can be transferred to the charge storage portion 18.

[0146] In some examples, the charge storage portion 18 may be of the second conductivity type, that is, the element doped in the charge storage portion 18 is different from the element doped in the first silicon active portion, and its specific configuration can refer to the above description, which will not be repeated here.

[0147] In some examples, the gate 110 of the first transmission tube 33 is disposed in the first enclosed area 12A, and the gate 110 of the first transmission tube 33 is coupled to the photoelectric device 15 and the charge storage unit 18 at the same time.

[0148] In some examples, the shading device 21 covers the isolation structure 11 around the charge storage portion 18 and a portion of the first silicon active portion bordering the isolation structure 11. The shading device 21 can absorb and reflect ambient stray light, making it difficult for ambient light to enter the charge storage portion 18, thereby reducing the parasitic light sensitivity of the pixel unit.

[0149] When the gate 110 of the first transmission tube 33 is electrically connected to the shading device 21, when a negative voltage is input to the gate 110 of the first transmission tube 33 in the charge storage stage (i.e., the stage in which the charge storage unit 18 stores charges), a negative voltage is also input to the shading device 21, which can enrich holes on the side wall of the isolation structure 11 below the shading device 21, passivate the defect state of the side wall of the isolation structure 11, and reduce the dark current of the pixel unit.

[0150] In some examples, the gate 17 of the second transmission tube 35 is disposed in the first enclosing area 12A and is located on one side of the storage gate 19, and the gate 17 of the second transmission tube 35 is also coupled to the charge storage unit 18. The gate 17 of the second transmission tube 35 can be located on the front side, the rear side, the left side or the right side of the storage gate 19, and the present disclosure does not limit the positional relationship between the two.

[0151] In some examples, a first floating diffusion 16A coupled to the gate 17 of the second transmission tube 35 is provided in the first enclosing area 12A, and a second floating diffusion 16B is provided in the second enclosing area 12B. The first floating diffusion 16A and the second floating diffusion 16B can be electrically connected through metal wires.

[0152] In some examples, the first floating diffusion 16A and the second floating diffusion 16B may be of the second conductivity type, that is, the elements doped in the first floating diffusion 16A and the second floating diffusion 16B are different from the elements doped in the first silicon active portion, and the specific configuration thereof may refer to the above description, which will not be repeated here.

[0153] In some examples, the gate 111 of the second reset transistor 39 is located in the second enclosing region 12B and coupled to the second floating diffusion 16B. The second reset transistor 39 can reset the first floating diffusion 16A and the second floating diffusion 16B.

[0154] In some examples, the gate 112 of the source follower 38 is located in the second enclosing region 12B and coupled to the second floating diffusion 16B. The source follower 38 can convert the photo-generated voltage signals of the first floating diffusion 16A and the second floating diffusion 16B into pixel output signals.

[0155] In some examples, the gate 113 of the row gate tube 37 is located in the second enclosing area 12B and coupled to the source follower 38 , and the row gate tube 37 can output the pixel output signal.

[0156] Some embodiments of the present disclosure further provide a terminal device, which includes the above-mentioned image sensor 100.

[0157] Since the terminal device includes the image sensor 100 , it has all the technical effects of the above-mentioned image sensor 100 , which will not be described in detail here.

[0158] The terminal device may be any device capable of using the image sensor 100, such as a mobile phone, a digital camera, a computer, a wearable device, a car, a medical device, a security device, or the like.

[0159] In the description of the present disclosure, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of the present disclosure, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0160] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0161] The embodiments, implementation methods and related technical features of the present disclosure may be combined or replaced with each other unless there is any conflict.

[0162] The above are only preferred embodiments of the present disclosure and are not intended to limit the present disclosure in any form. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present disclosure without departing from the content of the technical solution of the present disclosure are still within the scope of the technical solution of the present disclosure.

Claims

1. A pixel unit, characterized in that: include: A memory device, comprising a charge storage portion and a storage gate located on the charge storage portion; An isolation structure is arranged around the charge storage portion, and a first gap is formed between the isolation structure and the charge storage portion; as well as A shading device is located on the isolation structure and covers at least a portion of the first gap.

2. The pixel unit according to claim 1, characterized in that: The shading device is spaced apart from the storage gate, and the shading device covers a portion of the first gap.

3. The pixel unit according to claim 1, characterized in that: An extension direction of the shading device is the same as an extension direction of the first gap, and a length of the shading device is greater than or equal to a length of the first gap.

4. The pixel unit according to claim 1, characterized in that: It also includes a photoelectric device, wherein the photoelectric device and the storage device are located in a first enclosing area of ​​the isolation structure, the photoelectric device and the charge storage unit are arranged along a first direction, the first gap includes first sub-gaps located on opposite sides of the charge storage unit, two first sub-gaps are arranged along a second direction, and the second direction and the first direction intersect with each other; the shading device includes first sub-shading devices located on opposite sides of the charge storage unit in the second direction, and each of the first sub-shading devices covers a portion of the first sub-gap located on the same side.

5. The pixel unit according to any one of claims 1 to 4, characterized in that: It also includes a first transmission tube and a photoelectric device, wherein the input and output electrodes of the first transmission tube are electrically connected to the photoelectric device and the input electrode of the storage device respectively; the shading device and the gate electrode of the first transmission tube are made of the same material and are connected to each other.

6. The pixel unit according to any one of claims 1 to 4, characterized in that: The light shielding device is in contact with the isolation structure, and the light shielding device is configured to input a negative voltage during a process in which the charge storage portion stores charges.

7. The pixel unit according to claim 6, characterized in that: It also includes an optoelectronic device, wherein a second gap is formed between the optoelectronic device and the isolation structure, and the light shielding device covers a portion of the second gap.

8. The pixel unit according to claim 7, characterized in that: The extending direction of the shading device is the same as the extending direction of the second gap. The shading device includes an extending portion covering a portion of the second gap. The length of the extending portion is greater than or equal to the length of the second gap.

9. The pixel unit according to claim 7, characterized in that: The width of the shading device at the position corresponding to the first gap is equal to the width of the shading device at the position corresponding to the second gap.

10. The pixel unit according to claim 7, characterized in that: The photoelectric device and the charge storage part are arranged along a first direction, the first gap includes a first sub-gap located on opposite sides of the charge storage part, two first sub-gaps are arranged along a second direction, the second direction and the first direction intersect with each other, and the second gap includes a second sub-gap located on opposite sides of the photoelectric device in the second direction; the shading device includes two first sub-shading devices and two second sub-shading devices, the two first sub-shading devices are located on opposite sides of the charge storage part and respectively cover parts of the first sub-gap located on the same side, and the two second sub-shading devices are located on opposite sides of the photoelectric device and respectively cover parts of the second sub-gap located on the same side.

11. The pixel unit according to claim 6, characterized in that: It also includes a first transmission tube and a photoelectric device, wherein the input electrode and the output electrode of the first transmission tube are electrically connected to the input electrode of the photoelectric device and the storage device respectively; and the shading device is electrically connected to the gate of the first transmission tube.

12. The pixel unit according to any one of claims 1 to 4, characterized in that: Also includes: Optoelectronic devices; A first reset tube, electrically connected to the photoelectric device, and configured to reset the photoelectric device; a first transmission tube, electrically connected to the photoelectric device and the storage device, the first transmission tube being configured to transmit the charge of the photoelectric device to the storage device; as well as a second transmission tube, electrically connected to the storage device, the second transmission tube being configured to output the charge of the storage device; The isolation structure has a first enclosing area, and the first reset tube, the photoelectric device, the first transmission tube, the storage device and the second transmission tube are located in the first enclosing area.

13. The pixel unit according to claim 12, characterized in that: Also includes: a second reset tube, electrically connected to the second transmission tube at the first node, the second reset tube being configured to reset the first node; a source follower electrically connected to the first node, wherein the source follower is configured to amplify a voltage of the first node; as well as A row gate tube, electrically connected to the source follower, the row gate tube being configured to output the amplified voltage; The isolation structure has a second enclosing area, and the second reset transistor, the source follower and the row gate transistor are located in the second enclosing area.

14. An image sensor, characterized in that: The method comprises a pixel unit as claimed in any one of claims 1 to 13.

15. A terminal device, characterized in that: include: The image sensor of claim 14.

Images