Pixel structure and image sensor
By designing a periodically arranged isolation unit structure in the image sensor, the problem of difficulty in etching depth control in the deep groove isolation process is solved, and the effect of reducing crosstalk and improving image sensor performance is achieved.
Patent Information
- Application Number
- CN202323531464.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-22
- Publication Date
- 2025-02-11
- Estimated Expiration
- 2033-12-22
AI Technical Summary
When implementing the deep groove isolation process in the prior art, it is difficult to effectively control the etching depth, resulting in deterioration of image sensor performance.
A pixel structure is designed in which a plurality of pixel units are arranged periodically in rows and columns, and the deep groove isolation structure is composed of periodically distributed isolation units, and the isolation units include first and second isolation sub-units having gaps between each other. The extension direction of the first isolating subunit passes through the midpoint of the second isolating subunit.
Through this design, crosstalk between adjacent pixel units is reduced, and the depth of the deep groove isolation structure is effectively controlled, avoiding performance deterioration of the image sensor.
Smart Images
Figure CN222465201U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of imaging, in particular to a pixel structure and an image sensor comprising the pixel structure. Background Art
[0002] At present, with the rapid development of the intelligent era, cameras have become a familiar term for consumers, and the performance of photography is directly related to the image sensor (CIS) chip. As the pixel level of CMOS image sensors increases, the size of a single pixel becomes smaller and smaller, and the spacing between adjacent pixels also decreases, which leads to more serious crosstalk between adjacent pixels.
[0003] At present, deep trench isolation (DTI) is often used to set up deep trench isolation structures between adjacent pixels to reduce crosstalk between adjacent pixels. However, the etching depth of DTI is prone to unevenness, which in turn causes the performance of image sensors to deteriorate. Therefore, how to achieve overall DTI depth control is an urgent problem to be solved. Utility Model Content
[0004] In view of this, the utility model provides a pixel structure applied to an image sensor, the pixel structure comprising: a plurality of pixel units, arranged periodically in rows and columns; a deep trench isolation structure, the deep trench isolation structure comprising a plurality of isolation units periodically distributed in the pixel structure, the plurality of pixel units being located within a periodically repeating structure defined by the plurality of isolation units; wherein the isolation unit comprises at least a first isolation sub-unit and a second isolation sub-unit having a gap therebetween, the extension direction of the first isolation sub-unit passing through the midpoint of the second isolation sub-unit.
[0005] Optionally, in the deep trench isolation structure, the extension directions of the first isolation sub-unit and the second isolation sub-unit pass through each other's midpoints, and the length of the first isolation sub-unit in its extension direction is consistent with the length of the second isolation sub-unit in its extension direction.
[0006] Optionally, the isolation unit also includes: a third isolation sub-unit, which is parallel to the first isolation sub-unit and has a length in its extension direction that is greater than twice the length of the first isolation sub-unit in its extension direction; in the isolation unit, along the extension direction of the second isolation sub-unit, the first isolation sub-unit and the third isolation sub-unit are alternately arranged, and there is a gap between each isolation sub-unit.
[0007] Optionally, the extension direction of the second isolating sub-unit is at right angles to the extension directions of the first isolating sub-unit and the third isolating sub-unit; or, the extension direction of the second isolating sub-unit is at an angle of 45° to the extension directions of the first isolating sub-unit and the third isolating sub-unit.
[0008] Optionally, the length of the first isolating subunit in its extension direction is a, and the lengths of the second isolating subunit and the third isolating subunit in their respective extension directions are equal and are both b, wherein,
[0009] Optionally, the length of the first isolating subunit in its extending direction is a, and the length of the second isolating subunit in its extending direction is b, wherein, The third isolation subunit spans across the pixel structure along its extension direction.
[0010] Optionally, the isolation unit also includes: a fourth isolation sub-unit, which is parallel to the second isolation sub-unit and whose length in its extension direction is less than half of the length of the second isolation sub-unit in its extension direction; in the isolation unit, along the extension direction of the first isolation sub-unit, the second isolation sub-unit and the fourth isolation sub-unit are alternately arranged, and there is a gap between each isolation sub-unit.
[0011] Optionally, the length of the first isolating subunit in its extension direction is a, the lengths of the second isolating subunit and the third isolating subunit in their respective extension directions are equal and are both b, the extension direction of the fourth isolating subunit passes through the midpoint of the third isolating subunit, and the length of the fourth isolating subunit in its extension direction is c, wherein,
[0012] Optionally, the length of the first isolating subunit in its extending direction is a, the length of the second isolating subunit in its extending direction is b, and the length of the fourth isolating subunit in its extending direction is c, wherein, The third isolation subunit spans across the pixel structure along its extension direction.
[0013] Optionally, the lengths of the first isolating subunit and the second isolating subunit in their respective extension directions are equal and are both b, and the length of the fourth isolating subunit in its extension direction is c, wherein, The third isolation subunit spans across the pixel structure along its extension direction.
[0014] The present application also provides an image sensor, comprising the above-mentioned pixel structure and a microlens array consisting of a number of pixel units corresponding to the pixel structure, wherein the microlenses in the microlens array are arranged on a single pixel unit in a one-to-one correspondence.
[0015] The present application also provides an image sensor, comprising the above-mentioned pixel structure and a microlens array composed of a plurality of microlenses, each microlens being arranged on four adjacent same-color pixel units arranged in a 2×2 periodic pattern.
[0016] Compared with the prior art, the utility model has at least one of the following outstanding advantages:
[0017] The isolation subunits of the present application are distributed in the semiconductor substrate of the pixel structure at periodic intervals and form isolation units, so that multiple pixel units are located in a periodic repeating structure defined by multiple isolation units, thereby reducing crosstalk between adjacent pixel units. Since there are gaps between the isolation subunits, the problem of over-deep etching of some areas in the deep trench isolation process will not occur due to the intersection of the deep trench isolation structure, which is conducive to the depth control of the overall deep trench isolation structure and avoids the performance degradation problem of the image sensor. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 It is a schematic diagram of the local structure of DTI of the prior art pixel structure;
[0019] Figure 2 is a schematic structural diagram of a first isolation subunit and a second isolation subunit provided in an embodiment of the present application;
[0020] Figure 3 is a structural schematic diagram of a deep trench isolation structure provided in an embodiment of the present application;
[0021] Figure 4 is a structural schematic diagram of another deep trench isolation structure provided in an embodiment of the present application;
[0022] Figure 5 is a structural schematic diagram of another deep trench isolation structure provided in an embodiment of the present application;
[0023] Figure 6 is a structural schematic diagram of another deep trench isolation structure provided in an embodiment of the present application;
[0024] Figure 7 is a structural schematic diagram of another deep trench isolation structure provided in an embodiment of the present application;
[0025] Figure 8 is a structural schematic diagram of another deep trench isolation structure provided in an embodiment of the present application;
[0026] Fig. 9 is a structural schematic diagram of another deep trench isolation structure provided in an embodiment of the present application;
[0027] Fig.10 is a structural schematic diagram of another deep trench isolation structure provided in an embodiment of the present application;
[0028] Fig.11 is a structural schematic diagram of another deep trench isolation structure provided in an embodiment of the present application;
[0029] Fig.12 is a structural schematic diagram of another deep trench isolation structure provided in an embodiment of the present application;
[0030] Fig.13 is a structural schematic diagram of another deep trench isolation structure provided in an embodiment of the present application;
[0031] Fig.14 is a structural schematic diagram of another deep trench isolation structure provided in an embodiment of the present application;
[0032] Fig.15 is a structural schematic diagram of an image sensor provided in an embodiment of the present application;
[0033] Fig.16 It is a schematic diagram of the structure of another image sensor provided in an embodiment of the present application. DETAILED DESCRIPTION
[0034] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention will be further described below in conjunction with the accompanying drawings and embodiments.
[0035] It should be noted that the following description sets forth specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in a variety of other ways different from those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.
[0036] In the prior art, common patterns of DTI are as follows Figure 1 As shown, in the actual DTI etching process, due to the existence of corner rounding, the critical dimension of the intersection of DTI is easily enlarged, resulting in excessive etching of DTI, which is not conducive to the depth control of the overall DTI, and further causes the performance degradation of the image sensor.
[0037] This application proposes a solution to the above technical problems, mainly by avoiding the concept of DTI cross design, and proposes a series of possible solutions.
[0038] The present application provides a pixel structure applied to an image sensor, the pixel structure comprising: a plurality of pixel units arranged periodically in rows and columns; a deep trench isolation structure, the deep trench isolation structure comprising a plurality of isolation units periodically distributed in the pixel structure, the plurality of pixel units being located within a periodically repeating structure defined by the plurality of isolation units; wherein the isolation unit comprises at least a first isolation sub-unit and a second isolation sub-unit having a gap therebetween, the extension direction of the first isolation sub-unit passing through the midpoint of the second isolation sub-unit.
[0039] It can be understood that the extension direction refers to the length direction, that is, the direction in which the length in the isolation structure is relatively the largest. The extension direction of the isolation structure mentioned in the following embodiments of the present application is the same as the description here, and will not be repeated later. Furthermore, the midpoint of the second isolation subunit refers to the center point of the length distance of the second isolation subunit in its extension direction.
[0040] It can be understood that a gap between the first isolating sub-unit and the second isolating sub-unit means that the first isolating sub-unit and the second isolating sub-unit do not cross each other.
[0041] The present application embodiment provides a schematic diagram of the structure of the first isolation subunit and the second isolation subunit, please refer to Figure 2 (a)~(d), as shown in the figure, Figure 2 The first isolating sub-unit 110 and the second isolating sub-unit 120 are both straight-segment structures.
[0042] Optional, such as Figure 2 In (a) and (c), the angle between the extension direction X of the first isolating subunit 110 and the extension direction Y of the second isolating subunit 120 is 90°, that is, the extension direction X of the first isolating subunit 110 passes through the midpoint of the second isolating subunit 120 and is perpendicular to the second isolating subunit 120. At the same time, the length of the first isolating subunit 110 along its extension direction and the length of the second isolating subunit 120 along its extension direction can be the same (e.g. Figure 2 (a) in the figure), the length of the first isolating subunit 110 along its extension direction and the length of the second isolating subunit 120 along its extension direction may be different (eg Figure 2 (middle (c) figure).
[0043] Optional, such as Figure 2 In (b) and (d), the extension direction X of the first isolating subunit 110 and the extension direction Y of the second isolating subunit 120 form an acute angle greater than 0° and less than 90°, that is, while the extension direction X of the first isolating subunit 110 passes through the midpoint of the second isolating subunit 120, the extension directions of the first isolating subunit 110 and the second isolating subunit 120 intersect but are not perpendicular. At the same time, the length of the first isolating subunit 110 along its extension direction and the length of the second isolating subunit 120 along its extension direction can be the same (e.g. Figure 2 (b)), the length of the first isolating subunit 110 along its extension direction may be different from the length of the second isolating subunit 120 along its extension direction (eg Figure 2 (middle (d) figure).
[0044] The first isolation subunit 110 and the second isolation subunit 120 are periodically distributed in the semiconductor substrate of the pixel structure and form an isolation unit, so that multiple pixel units are located in a periodic repeating structure defined by multiple isolation units, thereby reducing crosstalk between adjacent pixel units. Since there is a gap between the first isolation subunit and the second isolation subunit, the problem of over-deep etching of some areas in the deep trench isolation process will not occur due to the intersection of the deep trench isolation structure, which is conducive to the depth control of the overall deep trench isolation structure and avoids the performance degradation problem of the image sensor.
[0045] Based on the above embodiments, the extension directions of the first isolation subunit and the second isolation subunit in the deep trench isolation structure pass through each other's midpoints, and the length of the first isolation subunit in its extension direction is consistent with the length of the second isolation subunit in its extension direction.
[0046] In some embodiments, Figure 3 As shown, a single isolation unit 100 includes a first isolation subunit 110 and a second isolation subunit 120 that are perpendicular to each other and have the same length, that is, while the extension direction X of the first isolation subunit 110 passes through the midpoint of the second isolation subunit 120, the extension direction of the second isolation subunit 120 passes through the midpoint of the first isolation subunit 110, and the length of the first isolation subunit 110 in its extension direction X is consistent with the length of the second isolation subunit in its extension direction Y. In other embodiments, such as Figure 4 As shown, a single isolation unit 100 includes a first isolation sub-unit 110 and a second isolation sub-unit 120 whose extension directions intersect but are not perpendicular and have the same length, that is, an acute angle greater than 0° and less than 90° is formed between the extension direction X of the first isolation sub-unit 110 and the extension direction Y of the second isolation sub-unit 120.
[0047] The multiple isolation units arranged in this way are periodically distributed in the pixel structure to form a deep trench isolation structure, which is used to reduce the crosstalk between adjacent pixel units. The gap between the first isolation subunit and the second isolation subunit is conducive to the depth control of the overall deep trench isolation structure, avoiding the performance degradation problem of the image sensor.
[0048] In some embodiments, Figure 5-8 As shown, Figure 5-8A schematic diagram of a deep trench isolation structure 10 provided in an embodiment of the present application. A single isolation unit 100 further includes: a third isolation subunit 130, which is parallel to the first isolation subunit 110 and has a length in its extension direction X greater than twice the length of the first isolation subunit 110 in its extension direction X, that is, the extension directions of the first isolation subunit 110 and the third isolation subunit 130 are both X; in each isolation unit 100, along the extension direction Y of the second isolation subunit 120, the first isolation subunit 110 and the third isolation subunit 130 are alternately arranged, and there is a gap between each isolation subunit.
[0049] Optionally, the first isolating subunit 110 , the second isolating subunit 120 , and the third isolating subunit 120 are all straight-segment structures.
[0050] Corresponds to Figure 5 and Figure 6 In an embodiment, a single isolation unit 100 includes two first isolation sub-units 110, three second isolation sub-units 120 and two third isolation sub-units 130, and the length of the first isolation sub-unit 110 in its extension direction X is a, the length of the second isolation sub-unit 120 in its extension direction Y is b, and the length of the third isolation sub-unit 130 in its extension direction X is also b, wherein, Furthermore, adjacent isolation units 100 along the extension direction X share a second isolation sub-unit 120 , and adjacent isolation units 100 along the extension direction Y share a third isolation sub-unit 130 .
[0051] The difference is that Figure 5 In the deep trench isolation structure 10 shown, the extension direction Y of the second isolation subunit 120 is at right angles to the extension direction X of the third isolation subunit 130, that is, the second isolation subunit 120 and the third isolation subunit 130 are perpendicular to each other. Since the third isolation subunit 130 is parallel to the first isolation subunit 110, the second isolation subunit 120 is perpendicular to the first isolation subunit 110 and the third isolation subunit 130 respectively; Figure 6 In the deep trench isolation structure 10, the extension direction Y of the second isolation subunit 120 intersects and is not perpendicular to the extension directions X of the first isolation subunit 110 and the third isolation subunit 130. Optionally, the extension direction Y of the second isolation subunit 120 forms an angle of 45° with the extension directions X of the first isolation subunit 110 and the third isolation subunit 130, respectively.
[0052] Corresponds to Figure 7 and Figure 8In the embodiment, a single isolation unit 100 includes two first isolation sub-units 110, three second isolation sub-units 120 and two third isolation sub-units 130, the length of the first isolation sub-unit 110 in its extension direction X is a, the length of the second isolation sub-unit 120 in its extension direction Y is b, wherein, The third isolation subunit 130 crosses the pixel structure along its extension direction X. Therefore, all isolation units 100 along the extension direction X share the third isolation subunit 130, and adjacent isolation units 100 along the extension direction X share one second isolation subunit 120, and adjacent isolation units 100 along the extension direction Y share one third isolation subunit 130.
[0053] The difference is that Figure 7 In the deep trench isolation structure 10 shown, the extension direction Y of the second isolation subunit 120 is at right angles to the extension direction X of the third isolation subunit 130, that is, the second isolation subunit 120 and the third isolation subunit 130 are perpendicular to each other. Since the third isolation subunit 130 is parallel to the first isolation subunit 110, the second isolation subunit 120 is perpendicular to the first isolation subunit 110 and the third isolation subunit 130 respectively; Figure 8 In the deep trench isolation structure 10, the extension direction Y of the second isolation subunit 120 intersects and is not perpendicular to the extension directions X of the first isolation subunit 110 and the third isolation subunit 130. Optionally, the extension direction Y of the second isolation subunit 120 forms an angle of 45° with the extension directions X of the first isolation subunit 110 and the third isolation subunit 130, respectively.
[0054] The multiple isolation units arranged in this way are periodically distributed in the pixel structure to form a deep trench isolation structure, which is used to reduce the crosstalk between adjacent pixel units. The gaps between the first isolation subunit, the second isolation subunit and the third isolation subunit are conducive to the depth control of the overall deep trench isolation structure, avoiding the performance degradation problem of the image sensor.
[0055] In some embodiments, Figure 9-12 As shown, Figure 9-12 A schematic diagram of a deep trench isolation structure 10 provided in an embodiment of the present application. A single isolation unit 100 further includes: a fourth isolation subunit 140, which is parallel to the second isolation subunit 120, that is, the extension direction of the second isolation subunit 120 and the fourth isolation subunit 140 are both Y, and the length of the fourth isolation subunit 140 in its extension direction Y is less than half of the length of the second isolation subunit 120 in its extension direction Y; in each isolation unit 100, along the extension direction X of the first isolation subunit 110, the second isolation subunit 120 and the fourth isolation subunit 140 are alternately arranged, and there is a gap between each isolation subunit.
[0056] Optionally, the first isolating subunit 110 , the second isolating subunit 120 , the third isolating subunit 130 and the fourth isolating subunit 140 are all straight-segment structures.
[0057] Corresponds to Fig. 9 and Fig.10 In an embodiment, a single isolation unit 100 includes two first isolation subunits 110, two second isolation subunits 120, two third isolation subunits 130, and two fourth isolation subunits 140, and the length of the first isolation subunit 110 in its extension direction X is a, the lengths of the second isolation subunit 120 and the third isolation subunit 130 in their respective extension directions are equal and are both b, the extension direction Y of the fourth isolation subunit 140 passes through the midpoint of the third isolation subunit 130, and the length of the fourth isolation subunit 140 in its extension direction Y is c, wherein, Furthermore, adjacent isolation units 100 along the extension direction X share a second isolation sub-unit 120 , and adjacent isolation units 100 along the extension direction Y share a third isolation sub-unit 130 .
[0058] The difference is that Fig. 9 In the deep trench isolation structure 10 shown, the extension direction Y of the second isolation subunit 120 is at right angles to the extension direction X of the third isolation subunit 130, that is, the second isolation subunit 120 and the third isolation subunit 130 are perpendicular to each other. Since the third isolation subunit 130 is parallel to the first isolation subunit 110, and the fourth isolation subunit 140 is parallel to the second isolation subunit 120, the second isolation subunit 120 is perpendicular to the first isolation subunit 110 and the third isolation subunit 130, respectively, and the first isolation subunit 110 and the fourth isolation subunit 140 are perpendicular to each other. Fig.10 In the deep trench isolation structure 10 shown, the extension direction Y of the second isolation sub-unit 120 and the fourth isolation sub-unit 140 intersects and is not perpendicular to the extension direction X of the first isolation sub-unit 110 and the third isolation sub-unit 130. Optionally, the extension direction Y of the second isolation sub-unit 120 forms an angle of 45° with the extension direction X of the first isolation sub-unit 110 and the third isolation sub-unit 130, and the extension direction Y of the fourth isolation sub-unit 140 forms an angle of 45° with the extension direction X of the first isolation sub-unit 110 and the third isolation sub-unit 130.
[0059] Corresponds to Fig.11 and Fig.12In the embodiment, a single isolation unit 100 includes two first isolation subunits 110, two second isolation subunits 120, two third isolation subunits 130 and two fourth isolation subunits 140, the length of the first isolation subunit 110 in its extension direction X is a, the length of the second isolation subunit 120 in its extension direction Y is b, and the length of the fourth isolation subunit 140 in its extension direction Y is c, wherein, The third isolation subunit 130 crosses the pixel structure along its extension direction. All isolation units 100 along the extension direction X share the third isolation subunit 130, and adjacent isolation units 100 along the extension direction X share one second isolation subunit 120, and adjacent isolation units 100 along the extension direction Y share one third isolation subunit 130.
[0060] The difference is that Fig.11 In the deep trench isolation structure 10 shown, the extension direction Y of the second isolation subunit 120 is at right angles to the extension direction X of the third isolation subunit 130, that is, the second isolation subunit 120 and the third isolation subunit 130 are perpendicular to each other. Since the third isolation subunit 130 is parallel to the first isolation subunit 110, and the fourth isolation subunit 140 is parallel to the second isolation subunit 120, the second isolation subunit 120 is perpendicular to the first isolation subunit 110 and the third isolation subunit 130, respectively, and the first isolation subunit 110 and the fourth isolation subunit 140 are perpendicular to each other. Fig.12 In the deep trench isolation structure 10 shown, the extension direction Y of the second isolation sub-unit 120 and the fourth isolation sub-unit 140 intersects and is not perpendicular to the extension direction X of the first isolation sub-unit 110 and the third isolation sub-unit 130. Optionally, the extension direction Y of the second isolation sub-unit 120 forms an angle of 45° with the extension direction X of the first isolation sub-unit 110 and the third isolation sub-unit 130, and the extension direction Y of the fourth isolation sub-unit 140 forms an angle of 45° with the extension direction X of the first isolation sub-unit 110 and the third isolation sub-unit 130.
[0061] Optional, continue to refer to Figure 9-12 In a single isolation unit 100, the gap between the two first isolation sub-units 110 is n1, the gap between the two fourth isolation sub-units 140 is n2, the gap between the first isolation sub-unit 110 and the second isolation sub-unit 120 is m1, and the gap between the third isolation sub-unit 130 and the fourth isolation sub-unit 140 is m2, n1 is greater than twice m1, and n2 is greater than twice m2, wherein n1 and n2 may be equal or unequal, depending on actual design requirements and are not limited here.
[0062] Corresponds to Fig.13 and Fig.14In the embodiment, a single isolation unit 100 includes a first isolation subunit 110, two second isolation subunits 120, two third isolation subunits 130 and two fourth isolation subunits 140, the length of the first isolation subunit 110 in its extension direction X is b, the length of the second isolation subunit 120 in its extension direction Y is also b, and the length of the fourth isolation subunit 140 in its extension direction Y is c, wherein, The third isolation subunit 130 crosses the pixel structure along its extension direction X. All isolation units 100 along the extension direction X share the third isolation subunit 130, and adjacent isolation units 100 along the extension direction X share one second isolation subunit 120, and adjacent isolation units 100 along the extension direction Y share one third isolation subunit 130.
[0063] The difference is that Fig.13 In the deep trench isolation structure 10 shown, the extension direction Y of the second isolation subunit 120 is at right angles to the extension direction X of the third isolation subunit 130, that is, the second isolation subunit 120 and the third isolation subunit 130 are perpendicular to each other. Since the third isolation subunit 130 is parallel to the first isolation subunit 110, and the fourth isolation subunit 140 is parallel to the second isolation subunit 120, the second isolation subunit 120 is perpendicular to the first isolation subunit 110 and the third isolation subunit 130, respectively, and the first isolation subunit 110 and the fourth isolation subunit 140 are perpendicular to each other. Fig.14 In the deep trench isolation structure 10 shown, the extension direction Y of the second isolation sub-unit 120 and the fourth isolation sub-unit 140 intersects and is not perpendicular to the extension direction X of the first isolation sub-unit 110 and the third isolation sub-unit 130. Optionally, the extension direction Y of the second isolation sub-unit 120 forms an angle of 45° with the extension direction X of the first isolation sub-unit 110 and the third isolation sub-unit 130, and the extension direction Y of the fourth isolation sub-unit 140 forms an angle of 45° with the extension direction X of the first isolation sub-unit 110 and the third isolation sub-unit 130.
[0064] In the above-mentioned multiple embodiments, the multiple isolation units arranged in this way are periodically distributed in the pixel structure to form a deep trench isolation structure, which is used to reduce the crosstalk between adjacent pixel units. Since there are gaps between the first isolation subunit, the second isolation subunit, the third isolation subunit and the fourth isolation subunit, the problem of over-deep etching of some areas in the deep trench isolation process will not occur due to the intersection of the deep trench isolation structure, which makes the critical dimension larger. Therefore, it is beneficial to control the depth of the overall deep trench isolation structure and avoid the performance degradation problem of the image sensor.
[0065] The present application also provides an image sensor, Fig.15 To include Figure 3The pixel structure of the embodiment shown and the microlens array composed of the number of pixel units in the corresponding pixel structure, the microlenses in the microlens array are arranged one by one on a single pixel unit. Of course, the microlens structure of this embodiment can also be arranged correspondingly in the pixel structure of any of the above embodiments, which is only for illustration. Fig.15 As shown, in the image sensor 1000, four pixel units are respectively located in four structures of the same size defined by the isolation unit 100 to reduce the crosstalk between adjacent pixel units. The microlenses 200 are arranged on each pixel unit one by one to converge the incident light and further reduce the crosstalk between adjacent pixel units. There are gaps between the isolation sub-units, so that the problem of excessive etching in some areas of the deep trench isolation process will not occur due to the intersection of the deep trench isolation structure, which is beneficial to the depth control of the overall deep trench isolation structure and avoids the performance degradation problem of the image sensor.
[0066] The above pixel structure can also be applied to the four-phase pixel (QPD) technology. The traditional method may be slow in focusing speed, but the QPD method can achieve higher speed autofocus due to the use of the four-phase pixel technology. Therefore, the present application also provides an image sensor, Fig.16 To include the above Figure 3 The pixel structure of the embodiment shown and the microlens array composed of a plurality of microlenses, of course, the microlens structure of this embodiment can also be correspondingly arranged in the pixel structure of any of the above embodiments, which is only used for illustration. Fig.16 As shown, in the image sensor 1000, each microlens 200 is arranged on four adjacent same-color pixel units arranged in a 2×2 periodic pattern, that is, one microlens 200 covers four same-color pixel units, and these four pixels can not only be divided into left and right to detect phase difference, but also support omnidirectional focusing in up and down and oblique directions. Since there are gaps between the isolation sub-units, the problem of over-deep etching in some areas of the deep trench isolation process will not occur due to the intersection of the deep trench isolation structure, which makes the critical dimensions larger. This is beneficial to the depth control of the overall deep trench isolation structure and avoids the performance degradation problem of the image sensor.
[0067] The above contents are further detailed descriptions of the present invention in combination with specific preferred implementations, and the specific implementation of the present invention cannot be considered to be limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.
Claims
1. A pixel structure, characterized in that: Applied to an image sensor, the pixel structure comprises: A plurality of pixel units are periodically arranged in rows and columns; A deep trench isolation structure, wherein the deep trench isolation structure comprises a plurality of isolation units periodically distributed in the pixel structure, and the plurality of pixel units are located in a periodically repeated structure defined by the plurality of isolation units; The isolation unit at least includes a first isolation sub-unit and a second isolation sub-unit with a gap therebetween, and an extension direction of the first isolation sub-unit passes through a midpoint of the second isolation sub-unit.
2. The pixel structure according to claim 1, characterized in that: In the deep trench isolation structure, the extension direction of the first isolation sub-unit and the second isolation sub-unit respectively passes through the midpoint of the other, and the length of the first isolation sub-unit in the extension direction is consistent with the length of the second isolation sub-unit in the extension direction.
3. The pixel structure according to claim 1, wherein: The isolation unit further comprises: A third isolating subunit, which is parallel to the first isolating subunit and has a length in its extending direction greater than twice the length of the first isolating subunit in its extending direction; In the isolation unit, along the extension direction of the second isolation sub-unit, the first isolation sub-units and the third isolation sub-units are alternately arranged at intervals, and there are gaps between the isolation sub-units.
4. The pixel structure according to claim 3, characterized in that: The extension direction of the second isolating subunit is at right angles to the extension directions of the first isolating subunit and the third isolating subunit respectively; or, The extension direction of the second isolating sub-unit forms an angle of 45° with the extension directions of the first isolating sub-unit and the third isolating sub-unit respectively.
5. The pixel structure according to claim 3 or 4, characterized in that: The length of the first isolating subunit in its extension direction is a, and the lengths of the second isolating subunit and the third isolating subunit in their respective extension directions are equal and are both b, wherein:
6. The pixel structure according to claim 3 or 4, characterized in that: The length of the first isolating subunit in its extending direction is a, and the length of the second isolating subunit in its extending direction is b, wherein: The third isolation subunit spans across the pixel structure along its extension direction.
7. The pixel structure according to claim 3 or 4, characterized in that: The isolation unit further comprises: a fourth isolating subunit, which is parallel to the second isolating subunit and has a length in an extending direction that is less than half of a length of the second isolating subunit in the extending direction; In the isolation unit, along the extension direction of the first isolation sub-unit, the second isolation sub-unit and the fourth isolation sub-unit are alternately arranged at intervals, and there is a gap between each of the isolation sub-units.
8. The pixel structure according to claim 7, characterized in that: The length of the first isolating subunit in its extension direction is a, the lengths of the second isolating subunit and the third isolating subunit in their respective extension directions are equal and are both b, the extension direction of the fourth isolating subunit passes through the midpoint of the third isolating subunit, and the length of the fourth isolating subunit in its extension direction is c, wherein, 9. The pixel structure according to claim 7, wherein: The length of the first isolating subunit in its extending direction is a, the length of the second isolating subunit in its extending direction is b, and the length of the fourth isolating subunit in its extending direction is c, wherein: The third isolation subunit spans across the pixel structure along its extension direction.
10. The pixel structure according to claim 7, wherein: The lengths of the first isolating subunit and the second isolating subunit in their respective extension directions are equal and are both b, and the length of the fourth isolating subunit in its extension direction is c, wherein: The third isolation subunit spans across the pixel structure along its extension direction.
11. An image sensor, comprising a pixel structure as claimed in any one of claims 1 to 10 and a microlens array consisting of a number corresponding to the number of pixel units in the pixel structure, wherein the microlenses in the microlens array are arranged on a single pixel unit in a one-to-one correspondence.
12. An image sensor, comprising the pixel structure according to any one of claims 1 to 10, and a microlens array composed of a plurality of microlenses, each of the microlenses being arranged on four adjacent pixel units of the same color arranged in a 2×2 periodic pattern.