A pixel array, a control method thereof, an image sensor, and an image acquisition device

Abstract

The application belongs to the technical field of sensors, and provides a pixel array, an image sensor and an image acquisition device. The pixel array comprises a plurality of pixels. Each pixel comprises a photosensitive region for converting a light signal into an electric charge signal, a charge isolation region arranged between the photosensitive regions, and a charge absorption region arranged at an edge region of the photosensitive region. The surface of the charge absorption region is connected to a voltage source. When the voltage source is turned on, the charge absorption region can absorb photoelectric charges diffused to the edge of the pixel from the photosensitive region, reduce the problem of a pink edge or a purple edge of an image edge caused by the overflow of the photoelectric charges of the pixel into adjacent pixels due to the overflow of the photoelectric charges, and effectively improve the image quality of the image sensor.

Description

Technical Field

[0001] This application belongs to the field of semiconductor technology, and particularly relates to a pixel array, an image sensor, and an image acquisition device. Background Technology

[0002] Image sensors include two types: CMOS (Complementary Metal-Oxide-Semiconductor) and CCD (Charge-Coupled Device), and are widely used in digital cameras, mobile phones, medical devices, automobiles, and other applications. With the continuous advancement of semiconductor manufacturing technology, image sensors are developing towards lower power consumption, higher integration, and smaller size. The rapid development of image sensor manufacturing technology has also led to higher requirements for the output image quality. For example, in many application areas such as smartphones, miniature surveillance devices, and digital cameras, the sensor chips used to acquire images are becoming increasingly miniaturized. In the design, manufacturing, and processing of image sensors, in order to reduce costs and chip area, it is necessary to consider optimizing pixel structure and processes to improve the quality of the pixel output image signal.

[0003] However, in practical applications, since image sensors typically include red, green, and blue pixels, the photosensitive area in each pixel is prone to overflow when it reaches saturation in collecting photoelectric charge. At this time, the overflowed charge in the photosensitive area is absorbed by the adjacent photosensitive area, resulting in charge signal interference. Summary of the Invention

[0004] This application provides a pixel array and its control method, an image sensor, and an image acquisition device, aiming to solve the problem of charge signal interference in image sensors.

[0005] The first aspect of this application provides a pixel array, the pixel array including a plurality of pixels, each pixel including a photosensitive area for converting light signals into charge signals;

[0006] A charge isolation region is provided between adjacent photosensitive areas to prevent signal interference between adjacent pixels;

[0007] At least one of the photosensitive areas has a charge absorption area along its edge for absorbing the charge overflowing from the photosensitive area;

[0008] The charge absorption region extends into the charge isolation region to form an electron transport channel at least in the charge isolation region, and the charge overflowing from the photosensitive region is transported to the charge absorption region at least via the electron transport channel.

[0009] In one embodiment, the depth of the charge absorption region is less than the depth of the charge isolation region, and the upper surface of the charge absorption region is not lower than the upper surface of the charge isolation region.

[0010] In one embodiment, the depth of the charge absorption region is between 1 / 10 and 1 / 20 of the depth of the charge isolation region.

[0011] In one embodiment, the charge isolation region is an ion-doped isolation region, and the charge absorption region and the charge isolation region have different ion doping types.

[0012] In one embodiment, the charge isolation region is a P-type isolation region, the charge absorption region is an N-type ion region, and the N-type ion region is electrically connected to a positive voltage source; or, the charge isolation region is an N-type isolation region, the charge absorption region is a P-type ion region, and the P-type ion region is electrically connected to a negative voltage source.

[0013] In one embodiment, the length of the charge absorption region is greater than 0.1 μm, the width of the charge absorption region is greater than 0.1 μm, and the depth of the charge absorption region is greater than 0.1 μm.

[0014] In one embodiment, the spacing between the charge absorption region and the photosensitive region is 0.05–0.1 μm.

[0015] In one embodiment, the charge isolation region includes at least a first region located below the charge absorption region and a second region surrounding the charge absorption region, wherein the doping concentration of the first region is greater than the doping concentration of the second region.

[0016] In one embodiment, at least one charge absorption region is provided between two adjacent photosensitive regions.

[0017] In one embodiment, each side of each photosensitive area is provided with the charge absorption area; or

[0018] Each of the photosensitive areas has a charge absorption area on its left and right sides; or

[0019] Each of the photosensitive areas has a charge absorption area on its front and rear sides; or

[0020] At least one diagonal position away from the epitaxial layer is provided for the charge absorption region in each of the photosensitive areas; or

[0021] Every four photosensitive areas constitute a pixel unit, and the center of the pixel unit is provided with the charge absorption area corresponding to the four photosensitive areas.

[0022] In one embodiment, the plurality of pixels includes at least a first pixel and a second pixel corresponding to different colors. The first pixel includes a first photosensitive area, and the second pixel includes a second photosensitive area. The oversaturation of the first photosensitive area is greater than the oversaturation of the second photosensitive area. The edge areas of the first photosensitive area and the second photosensitive area are both provided with charge absorption areas. The area of ​​the charge absorption area located at the edge area of ​​the first photosensitive area is greater than the area of ​​the charge absorption area located at the edge area of ​​the second photosensitive area.

[0023] This application also provides a method for controlling a pixel array, including the following steps:

[0024] Provide the pixel array described in any of the above embodiments;

[0025] A voltage is applied to the charge absorption region at least during the exposure process, such that the charge overflowing from the photosensitive region is transferred to the charge absorption region at least via the electron transport channel.

[0026] This application also provides an image sensor, which includes the pixel array described in any of the embodiments above.

[0027] In one embodiment, the image sensor is a CMOS image sensor or a CCD image sensor.

[0028] Finally, this application provides an image acquisition device, which includes a pixel array or image sensor according to any of the embodiments described above.

[0029] This application provides a pixel array, an image sensor, and an image acquisition device. The pixel array includes multiple pixels, each pixel including a photosensitive area for converting light signals into charge signals, a charge isolation area disposed between the photosensitive areas, and a charge absorption area disposed at the edge of the photosensitive area. The charge absorption area is connected to a voltage source. When the voltage source is turned on, the charge absorption area can absorb the photoelectric charge diffused from the photosensitive area to the pixel edge, reducing the problem of pink or purple edges on the image edge caused by the overflow of photoelectric charge and the absorption of oversaturated photoelectric charge by neighboring pixels, effectively improving the image quality acquired by the image sensor. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a planar schematic diagram of the pixel array of an image sensor in the prior art;

[0032] Figure 2 This is a cross-sectional schematic diagram of the pixel array of an image sensor in the prior art;

[0033] Figure 3 This is a planar schematic diagram of a pixel array provided in this application;

[0034] Figure 4 This is a cross-sectional schematic diagram of a pixel array provided in this application;

[0035] Figure 5 This is a schematic diagram of a test for the charge absorption of pixels in an image sensor provided in this application;

[0036] Figure 6 This is a cross-sectional schematic diagram of another pixel array provided in this application;

[0037] Figure 7 This is a planar schematic diagram of another pixel array provided in this application;

[0038] Figure 8 This is a planar schematic diagram of another pixel array provided in this application;

[0039] Figure 9 This is a planar schematic diagram of another pixel array provided in this application;

[0040] Figure 10 This is a planar schematic diagram of another pixel array provided in this application;

[0041] Figure 11 This is a planar schematic diagram of another pixel array provided in this application. Detailed Implementation

[0042] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present application.

[0043] The term "comprising," and any variations thereof, in the specification, claims, and accompanying drawings of this application are intended to cover a non-exclusive inclusion. For example, a process, method, system, product, or apparatus that comprises a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such processes, methods, products, or apparatus. Furthermore, the terms "first," "second," and "third," etc., are used to distinguish different objects, not to describe a specific order.

[0044] Figure 1 This is a schematic diagram of the pixel array of an image sensor in the prior art, combined with Figure 1 As shown, the pixel array of an image sensor includes multiple pixels arranged in an array, for example, Figure 1 The first pixel 11, the second pixel 12, the third pixel 13, the fourth pixel 21, the fifth pixel 22, the sixth pixel 23, the seventh pixel 31, the eighth pixel 32, and the ninth pixel 33 are arranged in an array. Typically, the pixel array includes red pixels, green pixels, and blue pixels. The three types of pixels form a pixel unit. The three types of pixels collect the photoelectric charge of the corresponding color light and generate an electrical signal for output.

[0045] Figure 1 The dashed line AB in the diagram represents the position of the sectional surface pointing inside the pixel. A schematic diagram of the sectional structure is shown below. Figure 2 As shown.

[0046] See Figure 2 As shown, each pixel in the pixel array includes a photosensitive region 101, a charge isolation region 102, an epitaxial layer 103, and a shallow trench isolation region 104. The photosensitive region 101 is located above the epitaxial layer 103, and the charge isolation region 102 is located between adjacent photosensitive regions 101. The shallow trench isolation region 104 is located above and inside the charge isolation region 102, surrounding the photosensitive region 101. When the pixel is working, the photosensitive region 101 collects photoelectric charge of the incident light of the corresponding color. When the photosensitive region 101 of the fifth pixel 22 reaches saturation due to excessive photoelectric charge collection, while the photoelectric charge collected by the photosensitive regions 101 of the fourth pixel 21 and the sixth pixel 23 has not reached saturation, the excess photoelectric charge in the photosensitive region 101 of the fifth pixel 22 overflows into the epitaxial layer 103 (e.g., ...). Figure 2As indicated by the arrows in the diagram, the particles diffuse randomly and disorderly within the epitaxial layer 103, thus moving to the vicinity of the fourth pixel 21 and the sixth pixel 23 and being captured by the photosensitive areas 101 of the fourth pixel region 21 and the sixth pixel region 23. Because the fourth pixel 21, the sixth pixel 23 and the fifth pixel 22 are pixels of different colors, the photosensitive areas 101 of the fourth pixel 21 and the sixth pixel 23 collect photoelectric charges that do not belong to them. This photoelectric charge signal interference phenomenon will cause image information distortion of the fourth pixel 21 and the sixth pixel 23, thereby causing the image acquired by the image sensor to have pink or purple edges at the edges of the bright image.

[0047] To address the aforementioned technical problems, this application provides a pixel array comprising multiple pixels. Each pixel includes a photosensitive area for converting light signals into charge signals. A charge isolation area is provided between adjacent photosensitive areas to prevent signal interference between adjacent pixels. By providing a charge absorption area along the edge of at least one photosensitive area, a potential difference is formed between the charge absorption area and the photosensitive area when a positive or negative voltage is applied to the charge absorption area. The charge absorption area can absorb the oversaturated photoelectric charge of the photosensitive area, thereby preventing the photosensitive area from being affected by the oversaturated photoelectric charge of adjacent photosensitive areas and eliminating charge signal interference in the image sensor.

[0048] For example, see Figure 3 As shown, Figure 3 This is a planar schematic diagram of a pixel array provided in an embodiment of this application. A charge absorption region 204 is provided at the boundary between the first pixel 11 and the fourth pixel 21, the boundary between the second pixel 12 and the fifth pixel 22, the boundary between the third pixel 13 and the sixth pixel 23, the boundary between the fourth pixel 21 and the seventh pixel 31, the boundary between the fifth pixel 22 and the eighth pixel 32, and the boundary between the sixth pixel 23 and the ninth pixel 33. The charge absorption region 204 is connected to a positive voltage terminal or a negative voltage terminal and can be used to absorb photoelectric charges near the edge of the pixel.

[0049] Figure 4 for Figure 3 See the cross-sectional view of the dashed line CD in the figure. Figure 4As shown, a charge isolation region 102 is provided around the adjacent photosensitive region 101. At least one charge absorption region 204 is provided at the edge of the photosensitive region 101, extending into the charge isolation region 102. The charge isolation region 102 is located between the photosensitive region 101 and the charge absorption region 204. When a positive or negative voltage source is connected to the charge absorption region 204, the charge isolation region 102 can exist as a conductor for electron transport, that is, an electron transport channel is formed in the charge isolation region 102. When a positive voltage source is connected to the charge absorption region 204, the negative charge overflowing from the photosensitive region 101 is transported to the charge absorption region 204 at least through the electron transport channel. Alternatively, when a negative voltage source is connected to the charge absorption region 204, the positive charge overflowing from the photosensitive region 101 enters the charge absorption region 204 through the electron transport channel formed by the charge isolation region 102. It should be explained that the movement of positive charge here refers to the movement of positive charge relative to negative charge. Through the above embodiments, the oversaturated photoelectric charge generated by the photosensitive area 101 can be adjusted so that the oversaturated charge of the photosensitive area 101 will not affect the adjacent photosensitive areas 101.

[0050] In this embodiment, the photosensitive area 101 of the fifth pixel 22 collects external photoelectric charges. When the photoelectric charges inside the fifth pixel 22 are located at the boundary of the fifth pixel 22, a potential difference is formed between the charge absorption area 204 of the external positive or negative voltage source and the photosensitive area 101. Therefore, the charge absorption area 204 absorbs the photoelectric charges near the edge of the fifth pixel 22 to prevent photoelectric charges from interfering with the adjacent second pixel 12 and eighth pixel 32. The photosensitive area 101 is responsible for collecting the photoelectric charges of the corresponding color. When the photoelectric charges received by the photosensitive area 101 of the fifth pixel 22 reach a saturation state, the excess photoelectric charges will overflow to the epitaxial layer 103. When the photoelectric charges in the epitaxial layer 103 move to the edge of the fifth pixel area 22, they will be absorbed by the charge absorption area 204. The photosensitive areas 101 of adjacent pixels will not collect the photoelectric charges that overflow to the epitaxial layer 103, so there will be no photoelectric charge signal interference phenomenon, thus solving the problem of pink and purple edges at the edges of bright images.

[0051] Understandably, the epitaxial layers 103 of two adjacent pixels are connected, and the photosensitive areas 101 of two adjacent pixels are isolated by charge isolation areas 102. For example, see... Figure 4 As shown, the common boundary position of the photosensitive area 101 of the eighth pixel 32 and the photosensitive area 101 of the fifth pixel 22 is isolated by the charge isolation area 102, and the common boundary area of ​​the fifth pixel 22 and the second pixel 12 is isolated by the charge isolation area 102.

[0052] In this embodiment, the oversaturated photoelectric charge in the photosensitive area 101 will move randomly. When it moves to the charge isolation area 102, it will be blocked by the isolation area to prevent interference with the photoelectric charge of the photosensitive area 101 of the adjacent pixel area.

[0053] In one embodiment, please see [link to previous article]. Figure 4 As shown, the charge absorption region 204 is disposed within the charge isolation region 102, and the depth of the charge absorption region 204 is less than the depth of the charge isolation region 102, and the upper surface of the charge absorption region 204 is not lower than the upper surface of the charge isolation region 102.

[0054] For example, see Figure 4 As shown, the charge absorption region 204 is disposed above the interior of the charge isolation region 102. The upper surface of the charge isolation region 102 may be higher than the surface of the charge isolation region 102 or coplanar with the upper surface of the charge isolation region 102. It can be understood that the upper surface of the charge absorption region 204 being coplanar with the upper surface of the charge isolation region 102 means that the charge absorption region 204 is directly doped on the upper surface of the charge isolation region. The fact that the upper surface of the charge absorption region 204 may be higher than the upper surface of the charge isolation region 102 means that the lower part of the charge absorption region 204 is located in the upper part of the charge isolation region 102 and extends into the insulating layer above the charge isolation region 102. In this embodiment of the invention, due to the addition of the charge absorption region 204 located in the silicon oxide insulating layer, the area of ​​the charge absorption region 204 is further increased, which can absorb more supersaturated photoelectric charges in the photosensitive region 101. Furthermore, setting the upper surface of the charge absorption region 204 to extend beyond the upper surface of the charge isolation region 102 makes it easier to connect an external positive voltage source or a negative voltage source.

[0055] In this embodiment, after the photosensitive area 101 generates photoelectric charge, the photoelectric charge will be distributed in any area of ​​the photosensitive area 101. The charge absorption area 204 is located inside and above the charge isolation area 102. At this time, because the charge absorption area 204 is connected to a positive or negative voltage source, it will collect the oversaturated photoelectric charge of the photosensitive area 101. The photoelectric charge will not overflow from the photosensitive area 101 to the epitaxial layer 103, and the photosensitive areas 101 of adjacent pixels will not collect this part of the photoelectric charge. Therefore, it will not cause charge signal interference, thereby preventing the oversaturated photoelectric charge of the photosensitive area 101 from affecting adjacent pixels and improving the photosensitive accuracy of the pixel area.

[0056] In one embodiment, the depth of the charge absorption region is between 1 / 10 and 1 / 20 of the depth of the charge isolation region. The depth of the charge absorption region can be understood as the depth of the overlapping portion of the charge absorption region and the charge isolation region. Optionally, the depth of the charge absorption region is 0.1 μm, and the depth of the charge isolation region is 1-2 μm. The depth of the charge isolation region is 10-20 times the depth of the charge absorption region. The charge absorption region can absorb supersaturated electrons from the photosensitive area without affecting the isolation of adjacent pixels by the charge isolation region.

[0057] In this embodiment, the charge isolation region is responsible for isolating adjacent pixels to prevent the penetration of photoelectric charges between adjacent pixels, and the charge absorption region can absorb oversaturated photoelectric charges.

[0058] In one embodiment, see Figure 4 As shown, the charge isolation region 102 is an ion-doped isolation region, and the charge absorption region 204 and the charge isolation region 102 have different ion doping types.

[0059] Understandably, the different ion doping types of the charge absorption region 204 and the charge isolation region 102 refer to the fact that one of them is N-type ion doped and the other is P-type ion doped. For example, the charge isolation region 102 is a P-type ion region, and the charge absorption region 204 is an N-type ion region, with the N-type ion region electrically connected to the positive voltage source; or the charge isolation region 102 is an N-type ion region, and the charge absorption region 204 is a P-type ion region, with the P-type ion region electrically connected to the negative voltage source. The P-type and N-type ion regions combine through doping to form a PN junction. A space charge region exists near the interface of the PN junction. This space charge region acts as an energy barrier for charge carriers, making it difficult for them to pass through. However, when an external power source is connected to the charge absorption region 204, the charge carriers can overcome the barrier, and the charge absorption region 204 can then absorb the supersaturated photoelectric charge overflowing from the photosensitive region 101.

[0060] In this embodiment, optionally, the ions in the N-type ion region can be arsenic ions, phosphorus ions, or a combination of arsenic and phosphorus ions; the ions in the P-type ion region can be boron ions, indium ions, or a combination of boron and indium ions; and the ion concentration in the N-type or P-type ion region is at least 1e18 ions / cm^3. The epitaxial layer 103 can be a P-type epitaxial layer of a semiconductor substrate, the photosensitive photodiode is disposed in the epitaxial layer 103, and the charge isolation region 102 is disposed in the P-type epitaxial layer of the semiconductor substrate.

[0061] In this embodiment, when the pixel array is set to an NMOS transistor, the charge isolation region 102 is a P-type ion region and the charge absorption region 204 is an N-type ion region. When the pixel array is set to a PMOS transistor, the charge isolation region 102 is an N-type ion region and the charge absorption region 204 is a P-type ion region.

[0062] In one embodiment, the length of the charge absorption region is greater than 0.1 μm, the width is greater than 0.1 μm, and the depth of the charge absorption region is greater than 0.1 μm.

[0063] For example, in a specific embodiment, see Figure 5 As shown, where, Figure 5 a is Figure 3 The cross-sectional view of the tangent CD position shown in the TCAD simulation shows the photosensitive area 101 in the middle, the charge isolation area 102 surrounding the photosensitive area 101, and the charge absorption area 204 located at the edge of the photosensitive area 101. In this embodiment of the invention, the pixel unit size is 0.95 μm, the depth of the photosensitive area 101 is 1.8 μm, the photoelectric charge received by the photosensitive area 101 is 1e6 charges / s, and the voltage value of the positive electrode connected to the charge absorption area 204 ranges from 0V to 1.4V. Figure 5 b is a graph showing the oversaturated photoelectric charge in photosensitive region 101 and the voltage at the positive terminal connected to charge absorption region 204 from 0V to 1.4V. Figure 5 As shown in Figure b, when the voltage at the positive terminal connected to the charge absorption region 204 is 0V, the total amount of charge overflowing from the photosensitive region 101 is the amount of charge released entirely into the epitaxial layer 103. As the voltage at the positive terminal connected to the charge absorption region 204 increases, the supersaturated photoelectric charge in the photosensitive region 101 is gradually absorbed by the charge absorption region 204. The higher the amount of charge absorbed by the charge absorption region 204, the lower the amount of charge overflowing from the photosensitive region 101 into the epitaxial layer 103, i.e., the amount of charge absorbed by the epitaxial layer 103. Figure 5 c is a schematic diagram showing the change in signal interference rate as a function of the voltage of the external voltage source in the charge absorption region 204. The signal interference rate is defined as the ratio of the amount of charge overflowing from the photosensitive region 101 to the epitaxial layer 103 (i.e., the amount of charge absorbed by the epitaxial layer 103) to the total amount of charge overflowing from the photosensitive region 101. Figure 5 As shown in Figure c, when the voltage at the positive terminal of the photosensitive region 101 is low, the signal interference rate is high. As the voltage at the positive terminal connected to the charge absorption region 204 increases, the signal interference rate gradually decreases. Therefore, setting a charge absorption region at the edge of the photosensitive region 101 can effectively absorb oversaturated charge and reduce charge crosstalk between adjacent photosensitive pixels.

[0064] In one embodiment, the spacing between the charge absorption region and the photosensitive region is 0.05-0.1 μm. It is understood that, since the charge absorption region extends into the charge isolation region, there is a charge isolation region of a certain thickness between the charge absorption region and the photosensitive region. On the one hand, the charge isolation region can act as an electron transport channel, allowing the charge in the photosensitive region to be absorbed by the charge absorption region; on the other hand, the charge isolation region can prevent the charge absorption region from absorbing any undischarged photoelectric charge in the photosensitive region.

[0065] Meanwhile, a distance of less than 0.1 μm between the charge absorption area and the photosensitive area is beneficial to enhancing the absorption capacity of the charge absorption area for oversaturated photoelectric charges, which helps to improve the oversaturated photoelectric charges in the photosensitive area. A distance of more than 0.05 μm between the charge absorption area and the photosensitive area helps to prevent the charge absorption area from absorbing the photoelectric charges that have not overflowed from the photosensitive area, which would cause the pixel brightness to darken.

[0066] In one embodiment, see Figure 6 As shown, the charge isolation region 102 includes at least a first region 601 located below the charge absorption region 204 and a second region 602 surrounding the charge absorption region 204, wherein the doping concentration of the first region 601 is greater than the doping concentration of the second region 602.

[0067] For example, in one embodiment, the first region 601 is a heavily p-type doped region, and the second region 602 is a p-type doped region or a lightly p-type doped region; or the first region 601 is a p-type doped region and the second region 602 is a lightly p-type doped region; or the first region 601 is a heavily n-type doped region and the second region 602 is an n-type doped region or a lightly n-type doped region; or the first region 601 is an n-type doped region and the second region 602 is a lightly n-type doped region.

[0068] Understandably, in this embodiment, the doping concentration of the first region of the charge isolation region 102 is low, and the charge absorption region 204 can more easily absorb the supersaturated photoelectric charge from the photosensitive region 101. Therefore, the voltage of the positive or negative voltage source connected to the surface of the charge absorption region 204 can be reduced. At the same time, if the doping concentration is low, the barrier width between the charge absorption region 204 and the charge isolation region 102 is wider, and Zener breakdown is less likely to occur. The charge absorption region 204 can absorb the saturated photoelectric charge more stably.

[0069] In one embodiment, the pixel array is arranged in the Bayer pixel array configuration.

[0070] In this embodiment, the Bayer pixel array includes red, green and blue pixels. Each of the three types of pixels is provided with a photodiode as a photosensitive area. The photosensitive areas of the three pixel areas collect photoelectric charges of the corresponding color light. They may reach saturation at different exposure times. Excess photoelectric charges in the photosensitive areas that saturate first will overflow into the epitaxial layer. The oversaturated photoelectric charges move to the vicinity of the photosensitive areas of neighboring pixels in the epitaxial layer and are then absorbed by the photosensitive areas of the adjacent pixels.

[0071] In one embodiment, at least one charge absorption region is provided between two adjacent photosensitive regions.

[0072] In this embodiment, see Figure 4 As shown, by providing at least one charge absorption region 204 between each of two adjacent photosensitive regions 101, when photosensitive region 101 generates photoelectric charge, the photoelectric charge will be distributed in any area of ​​photosensitive region 101. Since the charge absorption region 204 is connected to a positive or negative voltage source, it will collect the oversaturated photoelectric charge of photosensitive region 101. The photoelectric charge will not overflow from photosensitive region 101 to epitaxial layer 103, and the photosensitive region 101 of adjacent pixels will not collect this part of the photoelectric charge. Therefore, it will not cause charge signal interference, thereby preventing the oversaturated photoelectric charge of photosensitive region 101 from affecting adjacent pixels and improving the photosensitive accuracy of pixel area.

[0073] In one embodiment, each photosensitive area has a charge absorption area on its left and right sides. It can be understood that the left and right sides of the photosensitive area refer to opposite sides on the photosensitive area on a plane parallel to the sensor pixel array.

[0074] For example, see Figure 7 As shown, Figure 7 This is a planar schematic diagram of an image sensor pixel array. Charge absorption regions 204 are provided at the boundaries of the first pixel 11 and the second pixel 12, the boundaries of the second pixel 12 and the third pixel 13, the boundaries of the fourth pixel 21 and the fifth pixel 22, the boundaries of the fifth pixel 22 and the sixth pixel 23, the boundaries of the seventh pixel 31 and the eighth pixel 32, and the boundaries of the eighth pixel 32 and the ninth pixel 33, for absorbing photoelectric charges near the pixel edges.

[0075] In one embodiment, each photosensitive area has a charge absorption area on its front and rear sides. It can be understood that the front and rear sides of the photosensitive area refer to the other opposite sides of the photosensitive area on a plane parallel to the sensor pixel array.

[0076] For example, participate Figure 3As shown, a charge absorption region 204 exists at the boundary between the first pixel 11 and the fourth pixel 21, the boundary between the second pixel 12 and the fifth pixel 22, the boundary between the third pixel 13 and the sixth pixel 23, the boundary between the fourth pixel 21 and the seventh pixel 31, the boundary between the fifth pixel 22 and the eighth pixel 32, and the boundary between the sixth pixel 23 and the ninth pixel 33. The charge absorption region 204 is connected to a positive voltage source or a negative voltage source and can be used to absorb photoelectric charges near the pixel edge.

[0077] In one embodiment, a charge absorption region is provided between two adjacent photosensitive regions, and a charge absorption region is provided on each side of each photosensitive region. It can be understood that each side of the photosensitive region refers to each side of the photosensitive region on the plane of the image sensor pixel array.

[0078] For example, see Figure 8 As shown, Figure 8 This is a planar schematic diagram of a pixel array of an image sensor. A charge absorption region 204 is provided on the top, bottom, left, and right sides of the first pixel 11, the second pixel 12, the third pixel 13, the fourth pixel 21, the fifth pixel 22, the sixth pixel 23, the seventh pixel 31, the eighth pixel 32, and the ninth pixel 33 to absorb photoelectric charges near the edge of the pixel.

[0079] In one embodiment, each photosensitive region has a charge absorption region located at at least one diagonal position away from the epitaxial layer. It is understood that the diagonal position here refers to the diagonal position of the photosensitive region on the plane of the sensor pixel array.

[0080] For example, see Figure 9 As shown, Figure 9 This is a planar schematic diagram of an image sensor pixel array. A charge absorption region 204 is set at the upper left corner, upper right corner, lower left corner, and lower right corner of the first pixel 11, the second pixel 12, the third pixel 13, the fourth pixel 21, the fifth pixel 22, the sixth pixel 23, the seventh pixel 31, the eighth pixel 32, and the ninth pixel 33. Since the charge absorption region 204 is set in the charge isolation area of ​​the image sensor array, the charge absorption region 204 will not affect the photosensitive area of ​​each pixel in the photosensitive area. The photosensitive area in each pixel is equipped with four charge absorption regions 204 to absorb photoelectric charges near the edge of the pixel, which can avoid the existence of charge absorption blind spots when there are a lot of overflow charges.

[0081] In one embodiment, every four photosensitive areas constitute a pixel unit, and the center of the pixel unit is provided with a charge absorption area corresponding to the four photosensitive areas. It can be understood that the center of the pixel unit here refers to the center of the pixel unit on the plane of the sensor pixel array.

[0082] For example, see Figure 10 As shown, Figure 10 This is a planar schematic diagram of an image sensor pixel array. A charge absorption region 204 is provided at the upper right corner and lower left corner of the first pixel 11, the second pixel 12, the third pixel 13, the fourth pixel 21, the fifth pixel 22, the sixth pixel 23, the seventh pixel 31, the eighth pixel 32 and the ninth pixel 33. At this time, each charge absorption region 204 can be used to absorb photoelectric charges near the pixel edge in the four photosensitive regions 101.

[0083] For example, see Figure 11 As shown, Figure 11 This is a planar schematic diagram of an image sensor pixel array. A charge absorption region 204 is set at the junction of four adjacent pixels. At this time, each charge absorption region 204 can be used to absorb photoelectric charges near the pixel edge in the four photosensitive regions. Every four pixels share one charge absorption region 204, further reducing the number of charge absorption regions 204. At the same time, each pixel can be allocated a charge absorption region 204 to absorb photoelectric charges near the pixel edge.

[0084] In this embodiment, each pixel is adjacent to one, two, or four charge absorption regions 204. When a pixel area is exposed to a strong light environment, the photosensitive area 101 of the pixel collects too much photoelectric charge and overflows. Because the charge absorption region 204 is connected to a positive or negative voltage source, it will collect the oversaturated photoelectric charge of the photosensitive area 101. This prevents adjacent pixels from collecting this overflowing photoelectric charge, thus avoiding photoelectric charge signal interference. This eliminates the problem of pink or purple edges appearing at the edges of bright images captured by the image sensor.

[0085] In one embodiment, the plurality of pixels includes at least a first pixel and a second pixel corresponding to different colors. The first pixel includes a first photosensitive area, and the second pixel includes a second photosensitive area. The oversaturation of the first photosensitive area is greater than the oversaturation of the second photosensitive area. The edges of the first photosensitive area and the second photosensitive area are provided with charge absorption areas. The area of ​​the charge absorption area located at the edge of the first photosensitive area is greater than the area of ​​the charge absorption area located at the edge of the second photosensitive area.

[0086] It should be noted that the oversaturation here refers to the amount of charge generated in the photosensitive area that exceeds its full-well capacity.

[0087] For example, in sunlight, the area of ​​the charge absorption region corresponding to the green light absorbing pixel is larger than the area of ​​the charge absorption region corresponding to the red light and blue light absorbing pixels. In darkness, the area of ​​the charge absorption region corresponding to the red light absorbing pixel is larger than the area of ​​the charge absorption region corresponding to the blue light and green light absorbing pixels.

[0088] In this embodiment, the area of ​​the charge absorption region corresponding to the pixel can be adjusted according to the actual situation.

[0089] This embodiment also provides a method for controlling a pixel array, including the following steps:

[0090] Provide a pixel array as described in any of the above embodiments; at least during exposure, a voltage is applied to the charge absorption region such that the charge overflowing from the photosensitive region is transferred to the charge absorption region at least via an electron transport channel.

[0091] For example, in one embodiment, see Figure 4 As shown, during the exposure process, a positive voltage source or a negative voltage source applies a voltage to the charge absorption region 204. Applying a voltage to the charge absorption region 204 can form an electron transport channel between the photosensitive region 101 and the charge absorption region 204 to transport the oversaturated photoelectric charge of the photosensitive region 101. The charge absorption region 204 can absorb the oversaturated photoelectric charge from the photosensitive region 101.

[0092] In this embodiment, after the photosensitive area 101 absorbs photoelectric charge, the photoelectric charge will be distributed in any area of ​​the photosensitive area 101. The charge absorption area 204 is located inside and above the charge isolation area 102, not exceeding the edge of the charge isolation area 102. At this time, because the charge absorption area 204 is connected to a positive or negative voltage source, it will collect the oversaturated photoelectric charge of the photosensitive area 101. The photoelectric charge will not overflow from the photosensitive area 101 to the epitaxial layer 103, and the photosensitive areas 101 of adjacent pixels will not collect this part of the photoelectric charge. Therefore, it will not cause charge signal interference, thereby preventing the oversaturated photoelectric charge of the photosensitive area 101 from affecting adjacent pixels and improving the photosensitive accuracy of the pixel area.

[0093] This application also provides an image sensor, which includes the pixel array described in any of the above embodiments.

[0094] In one embodiment, the image sensor is a CMOS image sensor or a CCD image sensor.

[0095] In this embodiment, charge absorption regions can be provided around the photosensitive areas of both the CMOS image sensor and the CCD image sensor to absorb the supersaturated photoelectric charge from the photosensitive areas.

[0096] This application also provides an image acquisition device, which includes the image sensor pixel array and image sensor described in any of the above embodiments.

[0097] The pixel array includes multiple pixels, each pixel including a photosensitive area for converting light signals into charge signals, a charge isolation area disposed between the photosensitive areas, a charge absorption area disposed at the edge of the photosensitive area, and an epitaxial layer supporting the photosensitive area and the charge isolation area. The surface of the charge absorption area is connected to a voltage source. When the voltage source is turned on, the charge absorption area can absorb the photoelectric charge diffused from the photosensitive area to the pixel edge, reducing the problem of pink or purple edges on the image edge caused by the overflow of photoelectric charge and the absorption of oversaturated photoelectric charge by neighboring pixels, effectively improving the image quality acquired by the image sensor.

[0098] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0099] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0100] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0101] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0102] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A pixel array, comprising: The pixel includes a plurality of pixels, each of which includes a photosensitive region for converting a light signal into an electric charge signal; A charge isolation region is provided between adjacent photosensitive regions to prevent signal interference between adjacent pixels; An edge region of at least one of the photosensitive regions is provided with a charge absorption region for absorbing the overflow of the photosensitive region; The charge absorption region extends into the charge isolation region to form an electron transport channel in the charge isolation region, and the overflow of the photosensitive region is transported to the charge absorption region via the electron transport channel, and there is a certain thickness of the charge isolation region between the charge absorption region and the photosensitive region; The charge isolation region is an ion-doped isolation region, and the charge absorption region and the charge isolation region have different ion doping types; The charge isolation region is a P-type ion region, the charge absorption region is an N-type ion region, and the N-type ion region is electrically connected to a positive voltage source; or the charge isolation region is an N-type ion region, the charge absorption region is a P-type ion region, and the P-type ion region is electrically connected to a negative voltage source; the N-type ion region and the P-type ion region are combined by doping to form a PN junction, and a space charge region exists near the interface of the PN junction, and the charge absorption region absorbs the supersaturated photoelectric charges of the photosensitive region after being connected to a power supply.

2. The pixel array of claim 1, wherein, The depth of the charge absorption region is less than the depth of the charge isolation region, and the upper surface of the charge absorption region is not lower than the upper surface of the charge isolation region.

3. The pixel array of claim 2, wherein, The depth of the charge absorption region is between 1 / 10 and 1 / 20 of the depth of the charge isolation region.

4. The pixel array of claim 1, wherein, The length of the charge absorption region is greater than 0.1 um, the width of the charge absorption region is greater than 0.1 um, and the depth of the charge absorption region is greater than 0.1 um.

5. The pixel array of claim 1, wherein, The distance between the charge absorption region and the photosensitive region is 0.05-0.1 um.

6. The pixel array of claim 1, wherein, The charge isolation region includes at least a first region below the charge absorption region and a second region surrounding the charge absorption region, wherein the doping concentration of the first region is greater than the doping concentration of the second region.

7. The pixel array of claim 1, wherein, At least one charge absorption region is provided between two adjacent photosensitive regions.

8. The pixel array of claim 7, wherein, Each side of each photosensitive region is provided with the charge absorption region; or The left and right sides of each photosensitive region are provided with the charge absorption region; or The front and back sides of each photosensitive region are provided with the charge absorption region; or At least one diagonal position of each photosensitive region away from the epitaxial layer is provided with the charge absorption region; or Every four photosensitive regions form a pixel unit, and the center position of the pixel unit corresponding to the four photosensitive regions is provided with the charge absorption region.

9. The pixel array of any of claims 1-8, wherein, The plurality of pixels comprises at least a first pixel and a second pixel corresponding to different colors, the first pixel comprises a first light sensing region, the second pixel comprises a second light sensing region, the first light sensing region has a greater amount of oversaturation than the second light sensing region, and the first light sensing region and the second light sensing region each have a charge absorption region disposed at an edge region thereof, the charge absorption region disposed at the edge region of the first light sensing region has a greater area than the charge absorption region disposed at the edge region of the second light sensing region.

10. A method of controlling a pixel array, the method comprising: The method comprises the steps of: providing a pixel array as claimed in any of claims 1-9; applying a voltage to the charge absorption region at least during exposure to cause overflow charge from the light sensing region to be transported to the charge absorption region at least via the electron transport channel.

11. An image sensor, comprising: The image sensor comprises a pixel array as claimed in any of claims 1-9.

12. The image sensor of claim 11, wherein, The image sensor is a CMOS image sensor or a CCD image sensor.

13. An image acquisition device, characterized in that The image acquisition device comprises a pixel array as claimed in any of claims 1-9 or an image sensor as claimed in any of claims 11-12.

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