Pixel structure and image sensor
By designing a periodically distributed isolation unit structure in the image sensor, the problem of difficulty in depth control in the deep trench isolation process is solved, and the performance of the image sensor is improved.
Patent Information
- Application Number
- CN202311791927.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-22
- Publication Date
- 2025-06-27
AI Technical Summary
When the prior art adopts a deep trench isolation process in an image sensor, it is difficult to achieve overall depth control, resulting in deterioration of the 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. The isolation units include first and second isolation subunits having gaps between each other, and the extension direction of the first isolation subunit passes through the midpoint of the second isolation 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 CN120224813A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of imaging, and particularly to a pixel structure and an image sensor including the pixel structure. Background Art
[0002] Currently, with the rapid development of the intelligent era, cameras are already well-known to consumers, and the quality of the photographing performance is directly related to the image sensor (CIS) chip. With the improvement of the pixel level of the CMOS image sensor, the size of a single pixel is getting smaller and smaller, and the pitch between adjacent pixels is also decreasing. Along with this, the crosstalk between adjacent pixels is becoming more and more serious.
[0003] Currently, the deep trench isolation process (DTI) is often used to set a deep trench isolation structure between adjacent pixels to reduce the crosstalk between adjacent pixels. However, in the etching process of DTI, the phenomenon of inconsistent etching depth is likely to occur, thereby causing the performance degradation of the image sensor. Therefore, how to achieve the depth control of the overall DTI is an urgent problem to be solved. Summary of the Invention
[0004] In view of this, the present invention provides a pixel structure, which is applied to an image sensor. The pixel structure includes: a plurality of pixel units arranged periodically in rows and columns; a deep trench isolation structure, the deep trench isolation structure includes a plurality of isolation units periodically distributed in the pixel structure, and the plurality of pixel units are located in a periodically repeating structure defined by the plurality of isolation units; wherein, the isolation unit at least includes a first isolation sub-unit and a second isolation sub-unit having a gap therebetween, and the extending direction of the first isolation sub-unit passes through the midpoint of the second isolation sub-unit.
[0005] Optionally, in the deep trench isolation structure, the extending directions of the first isolation sub-unit and the second isolation sub-unit respectively pass through the midpoints of each other, and the length of the first isolation sub-unit in its extending direction is the same as the length of the second isolation sub-unit in its extending direction.
[0006] Optionally, the isolation unit further includes: a third isolation sub-unit, parallel to the first isolation sub-unit and having a length in its extending direction greater than twice the length of the first isolation sub-unit in its extending direction; in the isolation unit, along the extending direction of the second isolation sub-unit, the first isolation sub-unit and the third isolation sub-unit are alternately arranged at intervals, and there is a gap between each isolation sub-unit.
[0007] Optionally, the extending direction of the second isolation sub-unit forms a right angle with the extending directions of the first isolation sub-unit and the third isolation sub-unit respectively; or, the extending direction of the second isolation sub-unit forms a 45° angle with the extending directions of the first isolation sub-unit and the third isolation sub-unit respectively.
[0008] Optionally, the length of the first isolation sub-unit in its extending direction is a, and the lengths of the second isolation sub-unit and the third isolation sub-unit in their respective extending directions are equal and both are b, where
[0009] Optionally, the length of the first isolation sub-unit in its extending direction is a, and the length of the second isolation sub-unit in its extending direction is b, where The third isolation sub-unit extends across the pixel structure along its extending direction.
[0010] Optionally, the isolation unit further includes: a fourth isolation sub-unit, parallel to the second isolation sub-unit and having a length in its extending direction less than one half of the length of the second isolation sub-unit in its extending direction; in the isolation unit, along the extending 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 are gaps between the isolation sub-units.
[0011] Optionally, the length of the first isolation sub-unit in its extending direction is a, the lengths of the second isolation sub-unit and the third isolation sub-unit in their respective extending directions are equal and both are b, the extending direction of the fourth isolation sub-unit passes through the midpoint of the third isolation sub-unit, and the length of the fourth isolation sub-unit in its extending direction is c, where
[0012] Optionally, the length of the first isolation sub-unit in its extending direction is a, the length of the second isolation sub-unit in its extending direction is b, and the length of the fourth isolation sub-unit in its extending direction is c, where The third isolation sub-unit extends across the pixel structure along its extending direction.
[0013] Optionally, the lengths of the first isolation sub-unit and the second isolation sub-unit in their respective extending directions are equal and both are b, the length of the fourth isolation sub-unit in its extending direction is c, where The third isolation sub-unit extends across the pixel structure along its extending direction.
[0014] The present application further provides an image sensor, including the above pixel structure and a microlens array composed of the number of pixel units corresponding to the pixel structure, and the microlenses in the microlens array are arranged one by one on single pixel units.
[0015] The present application further provides an image sensor, including the above pixel structure and a microlens array composed of a plurality of microlenses, and each microlens is arranged on four adjacent same-color pixel units arranged in a 2×2 periodic pattern.
[0016] Compared with the prior art, the present invention has at least one of the following outstanding advantages:
[0017] The isolation sub-units of the present application are periodically and spacedly distributed in the semiconductor substrate of the pixel structure to form isolation units, such that multiple pixel units are located within the periodically repeating structure defined by the multiple isolation units, thereby reducing crosstalk between adjacent pixel units. Since there are gaps between the isolation sub-units, the problem of over-etching in some areas of the deep trench isolation process caused by the increase in critical dimension due to the intersection of the deep trench isolation structures will not occur. Therefore, it is beneficial to control the depth of the overall deep trench isolation structure and avoid the problem of performance degradation of the image sensor. Description of the Drawings
[0018] Figure 1 is a partial structural schematic diagram of the DTI of the prior art pixel structure;
[0019] Figure 2 is a structural schematic diagram of the first isolation sub-unit and the second isolation sub-unit provided by an embodiment of the present application;
[0020] Figure 3 is a structural schematic diagram of a deep trench isolation structure provided by an embodiment of the present application;
[0021] Figure 4 is a structural schematic diagram of another deep trench isolation structure provided by an embodiment of the present application;
[0022] Figure 5 is a structural schematic diagram of yet another deep trench isolation structure provided by an embodiment of the present application;
[0023] Figure 6 is a structural schematic diagram of yet another deep trench isolation structure provided by an embodiment of the present application;
[0024] Figure 7 is a structural schematic diagram of yet another deep trench isolation structure provided by an embodiment of the present application;
[0025] Figure 8 is a structural schematic diagram of yet another deep trench isolation structure provided by an embodiment of the present application;
[0026] Figure 9 is a structural schematic diagram of yet another deep trench isolation structure provided by an embodiment of the present application;
[0027] Figure 10 is a structural schematic diagram of yet another deep trench isolation structure provided by an embodiment of the present application;
[0028] Figure 11 is a structural schematic diagram of yet another deep trench isolation structure provided by an embodiment of the present application;
[0029] Figure 12 is a structural schematic diagram of yet another deep trench isolation structure provided by an embodiment of the present application;
[0030] Figure 13 It is a schematic structural diagram of another deep trench isolation structure provided by an embodiment of the present application;
[0031] Figure 14 It is a schematic structural diagram of another deep trench isolation structure provided by an embodiment of the present application;
[0032] Figure 15 It is a schematic structural diagram of an image sensor provided by an embodiment of the present application;
[0033] Figure 16 It is a schematic structural diagram of another image sensor provided by an embodiment of the present application. Detailed implementation manners
[0034] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described below with reference to the accompanying drawings and embodiments.
[0035] It should be noted that specific details are set forth in the following description to facilitate a thorough understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific implementation manners disclosed below.
[0036] In the prior art, common patterns of DTI are as Figure 1 shown. During the actual etching process of DTI, due to the existence of corner rounding, the critical dimension at the intersection of DTI is likely to become larger, resulting in over-etching of DTI, which is not conducive to the overall depth control of DTI and further causes the problem of performance degradation of the image sensor.
[0037] The present application proposes a solution to the above technical problems, mainly by avoiding the concept of DTI intersection design and proposing a series of possible solutions.
[0038] The present application provides a pixel structure applied to an image sensor. The pixel structure includes: a plurality of pixel units arranged periodically in rows and columns; a deep trench isolation structure, where the deep trench isolation structure includes a plurality of isolation units periodically distributed in the pixel structure, and the plurality of pixel units are located within the periodically repeating structure defined by the plurality of isolation units; wherein, the isolation unit at least includes a first isolation sub-unit and a second isolation sub-unit having a gap therebetween, and the extending direction of the first isolation sub-unit passes through the midpoint of the second isolation sub-unit.
[0039] It can be understood that the extending direction refers to the length direction, that is, the direction with the relatively largest length within the isolation structure. In the following embodiments of the present application, the extending direction of the isolation structure is the same as the description here, and will not be elaborated hereinafter. Further, the midpoint of the second isolation sub-unit refers to the center point of the length distance of the second isolation sub-unit in its extending direction.
[0040] It can be understood that there is a gap between the first isolation sub-unit and the second isolation sub-unit means that the first isolation sub-unit and the second isolation sub-unit do not cross each other.
[0041] An embodiment of the present application provides a schematic structural diagram of the first isolation sub-unit and the second isolation sub-unit. Please refer to Figure 2 (a)-(d), as shown in the figure, Figure 2 in which both the first isolation sub-unit 110 and the second isolation sub-unit 120 are straight segment structures.
[0042] Optionally, as Figure 2 in (a) and (c), an included angle of 90° is formed between the extending direction X of the first isolation sub-unit 110 and the extending direction Y of the second isolation sub-unit 120, that is, while the extending direction X of the first isolation sub-unit 110 passes through the midpoint of the second isolation sub-unit 120, it is perpendicular to the second isolation sub-unit 120. At the same time, the length of the first isolation sub-unit 110 along its extending direction and the length of the second isolation sub-unit 120 along its extending direction may be the same (as Figure 2 in figure (a)), the length of the first isolation sub-unit 110 along its extending direction and the length of the second isolation sub-unit 120 along its extending direction may be different (as Figure 2 in figure (c)).
[0043] Optionally, as Figure 2 in (b) and (d), an acute angle greater than 0° and less than 90° is formed between the extending direction X of the first isolation sub-unit 110 and the extending direction Y of the second isolation sub-unit 120, that is, while the extending direction X of the first isolation sub-unit 110 passes through the midpoint of the second isolation sub-unit 120, the extending directions of the first isolation sub-unit 110 and the second isolation sub-unit 120 intersect but are not perpendicular. At the same time, the length of the first isolation sub-unit 110 along its extending direction and the length of the second isolation sub-unit 120 along its extending direction may be the same (as Figure 2 in figure (b)), the length of the first isolation sub-unit 110 along its extending direction and the length of the second isolation sub-unit 120 along its extending direction may be different (as Figure 2 in figure (d)).
[0044] The above-mentioned first isolation sub-unit 110 and second isolation sub-unit 120 are periodically and spacedly distributed in the semiconductor substrate of the pixel structure and form an isolation unit, such that a plurality of pixel units are located within a periodically repeating structure defined by the plurality of isolation units, thereby reducing crosstalk between adjacent pixel units. And since there is a gap between the first isolation sub-unit and the second isolation sub-unit, there will be no problem that the key dimension becomes larger due to the crossing of the deep trench isolation structure and the etching of some areas of the deep trench isolation process is too deep. Therefore, it is beneficial to the depth control of the overall deep trench isolation structure and avoids the problem of performance degradation of the image sensor.
[0045] Based on the above embodiments, in the deep trench isolation structure, the extending directions of the first isolation sub-unit and the second isolation sub-unit respectively pass through the midpoints of each other, and the length of the first isolation sub-unit in its extending direction is the same as the length of the second isolation sub-unit in its extending direction.
[0046] In some embodiments, as Figure 3 shown, a single isolation unit 100 includes a first isolation sub-unit 110 and a second isolation sub-unit 120 that are perpendicular to each other and have the same length. That is, while the extending direction X of the first isolation sub-unit 110 passes through the midpoint of the second isolation sub-unit 120, the extending direction of the second isolation sub-unit 120 passes through the midpoint of the first isolation sub-unit 110, and the length of the first isolation sub-unit 110 in its extending direction X is the same as the length of the second isolation sub-unit in its extending direction Y. In other embodiments, as Figure 4 shown, a single isolation unit 100 includes a first isolation sub-unit 110 and a second isolation sub-unit 120 whose extending directions intersect and are not perpendicular and have the same length. That is, an acute angle greater than 0° and less than 90° is formed between the extending direction X of the first isolation sub-unit 110 and the extending direction Y of the second isolation sub-unit 120.
[0047] The plurality of isolation units arranged in this way are periodically distributed in the pixel structure to form a deep trench isolation structure for reducing crosstalk between adjacent pixel units. And there is a gap between the first isolation sub-unit and the second isolation sub-unit, which is beneficial to the depth control of the overall deep trench isolation structure and avoids the problem of performance degradation of the image sensor.
[0048] In some embodiments, as Figures 5 - 8 shown, Figures 5 - 8Schematic diagram of the deep trench isolation structure 10 provided by the embodiment of the present application. A single isolation unit 100 further includes: a third isolation sub-unit 130, which is parallel to the first isolation sub-unit 110 and has a length greater than twice the length of the first isolation sub-unit 110 in its extension direction X, that is, the extension directions of both the first isolation sub-unit 110 and the third isolation sub-unit 130 are X; in each isolation unit 100, along the extension direction Y of the second isolation sub-unit 120, the first isolation sub-unit 110 and the third isolation sub-unit 130 are alternately arranged at intervals, and there are gaps between the isolation sub-units.
[0049] Optionally, the first isolation sub-unit 110, the second isolation sub-unit 120, and the third isolation sub-unit 120 are all straight segment structures.
[0050] Corresponding to Figure 5 and Figure 6 In the embodiment of, 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, and the length of the third isolation sub-unit 130 in its extension direction X is also b. Among them, And 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 sub-unit 120 is perpendicular to the extension direction X of the third isolation sub-unit 130, that is, the second isolation sub-unit 120 and the third isolation sub-unit 130 are perpendicular to each other. Since the third isolation sub-unit 130 is parallel to the first isolation sub-unit 110, the second isolation sub-unit 120 is perpendicular to the first isolation sub-unit 110 and the third isolation sub-unit 130 respectively; while Figure 6 In the deep trench isolation structure 10 shown, the extension direction Y of the second isolation sub-unit 120 intersects with the extension directions X of the first isolation sub-unit 110 and the third isolation sub-unit 130 but is not perpendicular. Optionally, the extension direction Y of the second isolation sub-unit 120 forms a 45° angle with the extension directions X of the first isolation sub-unit 110 and the third isolation sub-unit 130 respectively.
[0052] Corresponding to Figure 7 and Figure 8In 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. The length of the first isolation sub-unit 110 in its extending direction X is a, and the length of the second isolation sub-unit 120 in its extending direction Y is b. Among them, The third isolation sub-unit 130 extends across the pixel structure along its extending direction X. Therefore, all the isolation units 100 along the extending direction X share the third isolation sub-unit 130, and adjacent isolation units 100 along the extending direction X share a second isolation sub-unit 120, and adjacent isolation units 100 along the extending direction Y share a third isolation sub-unit 130.
[0053] The difference is that, Figure 7 In the deep trench isolation structure 10 shown, the extending direction Y of the second isolation sub-unit 120 is perpendicular to the extending direction X of the third isolation sub-unit 130, that is, the second isolation sub-unit 120 is perpendicular to the third isolation sub-unit 130. Since the third isolation sub-unit 130 is parallel to the first isolation sub-unit 110, the second isolation sub-unit 120 is perpendicular to the first isolation sub-unit 110 and the third isolation sub-unit 130 respectively; while Figure 8 In the deep trench isolation structure 10 shown, the extending direction Y of the second isolation sub-unit 120 intersects with the extending directions X of the first isolation sub-unit 110 and the third isolation sub-unit 130 and is not perpendicular. Optionally, the extending direction Y of the second isolation sub-unit 120 forms a 45° angle with the extending directions X of the first isolation sub-unit 110 and the third isolation sub-unit 130 respectively.
[0054] Multiple isolation units arranged in this way are periodically distributed in the pixel structure to form a deep trench isolation structure for reducing crosstalk between adjacent pixel units. There are gaps between the first isolation sub-unit, the second isolation sub-unit, and the third isolation sub-unit, which is beneficial to the depth control of the overall deep trench isolation structure and avoids the problem of performance degradation of the image sensor.
[0055] In some embodiments, as Figures 9 - 12 shown, Figures 9 - 12 is a schematic diagram of the deep trench isolation structure 10 provided by the embodiment of the present application. A single isolation unit 100 further includes: a fourth isolation sub-unit 140, which is parallel to the second isolation sub-unit 120, that is, the extending directions of the second isolation sub-unit 120 and the fourth isolation sub-unit 140 are both Y, and the length of the fourth isolation sub-unit 140 in its extending direction Y is less than half of the length of the second isolation sub-unit 120 in its extending direction Y; in each isolation unit 100, along the extending direction X of the first isolation sub-unit 110, the second isolation sub-unit 120 and the fourth isolation sub-unit 140 are alternately arranged at intervals, and there are gaps between the isolation sub-units.
[0056] Optionally, the first isolation sub-unit 110, the second isolation sub-unit 120, the third isolation sub-unit 130 and the fourth isolation sub-unit 140 are all straight-section structures.
[0057] Corresponding to Figure 9 and Figure 10 In the embodiments corresponding to and
[0058] the difference is that Figure 9 in the deep trench isolation structure 10 shown, the extending direction Y of the second isolation sub-unit 120 is perpendicular to the extending direction X of the third isolation sub-unit 130, that is, the second isolation sub-unit 120 and the third isolation sub-unit 130 are perpendicular to each other. Since the third isolation sub-unit 130 is parallel to the first isolation sub-unit 110 and the fourth isolation sub-unit 140 is parallel to the second isolation sub-unit 120, the second isolation sub-unit 120 is perpendicular to the first isolation sub-unit 110 and the third isolation sub-unit 130 respectively, and the first isolation sub-unit 110 and the fourth isolation sub-unit 140 are perpendicular to each other pairwise. And Figure 10 in the deep trench isolation structure 10 shown, the extending direction Y of the second isolation sub-unit 120 and the fourth isolation sub-unit 140 intersects with the extending direction X of the first isolation sub-unit 110 and the third isolation sub-unit 130 non-perpendicularly. Optionally, the extending direction Y of the second isolation sub-unit 120 forms a 45° angle with the extending direction X of the first isolation sub-unit 110 and the third isolation sub-unit 130 respectively, and the extending direction Y of the fourth isolation sub-unit 140 forms a 45° angle with the extending direction X of the first isolation sub-unit 110 and the third isolation sub-unit 130 respectively.
[0059] Corresponding to Figure 11 and Figure 12In an embodiment, a single isolation unit 100 includes two first isolation sub-units 110, two second isolation sub-units 120, two third isolation sub-units 130, and two fourth isolation sub-units 140. The length of the first isolation sub-unit 110 in its extending direction X is a, the length of the second isolation sub-unit 120 in its extending direction Y is b, and the length of the fourth isolation sub-unit 140 in its extending direction Y is c. Among them, The third isolation sub-unit 130 extends across the pixel structure along its extending direction. All the isolation units 100 along the extending direction X share the third isolation sub-unit 130, and adjacent isolation units 100 along the extending direction X share one second isolation sub-unit 120, and adjacent isolation units 100 along the extending direction Y share one third isolation sub-unit 130.
[0060] The difference is that, Figure 11 In the deep trench isolation structure 10 shown, the extending direction Y of the second isolation sub-unit 120 is perpendicular to the extending direction X of the third isolation sub-unit 130, that is, the second isolation sub-unit 120 and the third isolation sub-unit 130 are perpendicular to each other. Since the third isolation sub-unit 130 is parallel to the first isolation sub-unit 110 and the fourth isolation sub-unit 140 is parallel to the second isolation sub-unit 120, the second isolation sub-unit 120 is perpendicular to the first isolation sub-unit 110 and the third isolation sub-unit 130 respectively, and the first isolation sub-unit 110 and the fourth isolation sub-unit 140 are perpendicular to each other pairwise. And Figure 12 In the deep trench isolation structure 10 shown, the extending direction Y of the second isolation sub-unit 120 and the fourth isolation sub-unit 140 intersects with the extending direction X of the first isolation sub-unit 110 and the third isolation sub-unit 130 and is not perpendicular. Optionally, the extending direction Y of the second isolation sub-unit 120 forms a 45° angle with the extending direction X of the first isolation sub-unit 110 and the third isolation sub-unit 130 respectively, and the extending direction Y of the fourth isolation sub-unit 140 forms a 45° angle with the extending direction X of the first isolation sub-unit 110 and the third isolation sub-unit 130 respectively.
[0061] Optionally, continuing to refer to Figures 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. Among them, n1 and n2 may be equal or not, which is determined according to actual design requirements and is not limited here.
[0062] Corresponding to Figure 13 and Figure 14In an embodiment, a single isolation unit 100 includes a first isolation sub-unit 110, two second isolation sub-units 120, two third isolation sub-units 130, and two fourth isolation sub-units 140. The length of the first isolation sub-unit 110 in its extending direction X is b, the length of the second isolation sub-unit 120 in its extending direction Y is also b, and the length of the fourth isolation sub-unit 140 in its extending direction Y is c. Among them, The third isolation sub-unit 130 spans across the pixel structure along its extending direction X. All the isolation units 100 along the extending direction X share the third isolation sub-unit 130, and adjacent isolation units 100 along the extending direction X share a second isolation sub-unit 120, and adjacent isolation units 100 along the extending direction Y share a third isolation sub-unit 130.
[0063] The difference is that, Figure 13 In the shown deep trench isolation structure 10, the extending direction Y of the second isolation sub-unit 120 is perpendicular to the extending direction X of the third isolation sub-unit 130, that is, the second isolation sub-unit 120 is perpendicular to the third isolation sub-unit 130. Since the third isolation sub-unit 130 is parallel to the first isolation sub-unit 110 and the fourth isolation sub-unit 140 is parallel to the second isolation sub-unit 120, the second isolation sub-unit 120 is perpendicular to the first isolation sub-unit 110 and the third isolation sub-unit 130 respectively, and the first isolation sub-unit 110 and the fourth isolation sub-unit 140 are perpendicular to each other pairwise. And Figure 14 In the shown deep trench isolation structure 10, the extending direction Y of the second isolation sub-unit 120 and the fourth isolation sub-unit 140 intersects with the extending direction X of the first isolation sub-unit 110 and the third isolation sub-unit 130 non-perpendicularly. Optionally, the extending direction Y of the second isolation sub-unit 120 forms a 45° angle with the extending direction X of the first isolation sub-unit 110 and the third isolation sub-unit 130 respectively, and the extending direction Y of the fourth isolation sub-unit 140 forms a 45° angle with the extending direction X of the first isolation sub-unit 110 and the third isolation sub-unit 130 respectively.
[0064] In the above-mentioned multiple embodiments, multiple isolation units arranged in this way are periodically distributed in the pixel structure to form a deep trench isolation structure for reducing crosstalk between adjacent pixel units. There are gaps between the first isolation sub-unit, the second isolation sub-unit, the third isolation sub-unit, and the fourth isolation sub-unit, so the problem of over-etching in some areas of the deep trench isolation process will not occur due to the increase in critical dimensions caused by the intersection of the deep trench isolation structure. Therefore, it is beneficial to control the depth of the overall deep trench isolation structure and avoid the problem of performance degradation of the image sensor.
[0065] This application also provides an image sensor, Figure 15 which includes Figure 3The pixel structure of the illustrated embodiment 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 correspondingly arranged in the pixel structure of any of the above embodiments, and only for illustration here. As Figure 15 shown, in the image sensor 1000, four pixel units are respectively located in four structures with the same size defined by the isolation unit 100 to reduce the crosstalk between adjacent pixel units. The microlenses 200 are arranged one by one on each pixel unit 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 over-etching in some areas of the deep trench isolation process caused by the increase of the critical dimension due to the intersection of the deep trench isolation structure will not occur, which is beneficial to the depth control of the overall deep trench isolation structure and avoids the problem of performance degradation of the image sensor.
[0066] The above pixel structure can also be applied to the quad-phase pixel (QPD) technology. The traditional method may be slower in terms of focusing speed, while the QPD method can achieve higher-speed autofocus due to the adoption of the quad-phase pixel technology. Therefore, the present application also provides an image sensor, Figure 16 which includes the Figure 3 pixel structure of the illustrated embodiment and the microlens array composed of several microlenses. Of course, the microlens structure of this embodiment can also be correspondingly arranged in the pixel structure of any of the above embodiments, and only for illustration here. As Figure 16 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. These four pixels can not only be divided into left and right to detect the phase difference, but also support omnidirectional focusing in the up-down and diagonal directions. There are gaps between the isolation sub-units, so that the problem of over-etching in some areas of the deep trench isolation process caused by the increase of the critical dimension due to the intersection of the deep trench isolation structure will not occur, which is beneficial to the depth control of the overall deep trench isolation structure and avoids the problem of performance degradation of the image sensor.
[0067] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should all be regarded as belonging to the protection scope of the present invention.
Claims
1. A pixel structure, characterized in that, Applied to an image sensor, the pixel structure includes: A plurality of pixel units, arranged periodically in rows and columns; A deep trench isolation structure, the deep trench isolation structure includes a plurality of isolation units periodically distributed in the pixel structure, and the plurality of pixel units are located within the periodically repeating structure defined by the plurality of isolation units; Wherein, the isolation unit at least includes a first isolation sub-unit and a second isolation sub-unit having a gap therebetween, and the extending direction of the first isolation sub-unit passes through the 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 extending directions of both the first isolation sub-unit and the second isolation sub-unit respectively pass through the midpoint of the other, and the length of the first isolation sub-unit in its extending direction is the same as the length of the second isolation sub-unit in its extending direction.
3. The pixel structure according to claim 1, characterized in that, The isolation unit further includes: A third isolation sub-unit, parallel to the first isolation sub-unit and having a length in its extending direction greater than twice the length of the first isolation sub-unit in its extending direction; In the isolation unit, along the extending direction of the second isolation sub-unit, the first isolation sub-unit and the third isolation sub-unit are alternately arranged at intervals, and there is a gap between each of the isolation sub-units.
4. The pixel structure according to claim 3, wherein The extending direction of the second isolation sub-unit forms a right angle with the extending directions of the first isolation sub-unit and the third isolation sub-unit respectively; or, The extending direction of the second isolation sub-unit forms a 45° angle with the extending directions of the first isolation sub-unit and the third isolation sub-unit respectively.
5. The pixel structure according to claim 3 or 4, characterized in that The length of the first isolation unit in its extending direction is a, and the lengths of the second isolation unit and the third isolation unit in their respective extending directions are equal and both are b, where 6. The pixel structure according to claim 3 or 4, characterized in that, The length of the first isolation unit in its extending direction is a, and the length of the second isolation unit in its extending direction is b, where, The third isolation sub-unit spans the pixel structure along its extending direction.
7. The pixel structure according to claim 3 or 4, characterized in that, The isolation unit further includes: A fourth isolation sub-unit, parallel to the second isolation sub-unit and having a length in its extending direction less than half of the length of the second isolation sub-unit in its extending direction; In the isolation unit, along the extending 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, wherein The length of the first isolation unit in its extending direction is a, the lengths of the second isolation unit and the third isolation unit in their respective extending directions are equal and both are b, the extending direction of the fourth isolation unit passes through the midpoint of the third isolation unit, and the length of the fourth isolation unit in its extending direction is c, where 9. The pixel structure according to claim 7, wherein The length of the first isolation unit in its extending direction is a, the length of the second isolation unit in its extending direction is b, and the length of the fourth isolation unit in its extending direction is c, where The third isolation unit extends across the pixel structure along its extending direction.
10. The pixel structure according to claim 7, characterized in that, The lengths of the first isolation unit and the second isolation unit in their respective extending directions are equal and both are b, and the length of the fourth isolation unit in its extending direction is c, where, The third isolation sub-unit spans the pixel structure along its extending direction.
11. An image sensor, including the pixel structure according to any one of claims 1-10 and a microlens array corresponding to the number of pixel units in the pixel structure, and the microlenses in the microlens array are arranged one by one on a single pixel unit.
12. An image sensor, including the pixel structure according to any one of claims 1-10, and a microlens array composed of a plurality of microlenses, and each microlens is arranged on four adjacent same-color pixel units arranged in a 2×2 periodic arrangement.