A small pixel CCD structure

Abstract

The application relates to a small-pixel CCD structure, which comprises a substrate, a buried groove arranged on the substrate, a plurality of vertical CCD driving gates arranged on the buried groove, a plurality of groove resistors arranged on the substrate, a plurality of metal leads arranged on the vertical CCD driving gates and parallel to the groove resistors, an expansion structure arranged below each metal lead corresponding to the vertical CCD driving gate, a contact hole arranged in the middle of the expansion structure, and a vertical driving phase of the vertical CCD driving gate electrically connected with the metal lead through metal filled in the contact hole. In the application, the expansion structure is added in the area where the contact hole is needed to be made in the vertical driving phase, the area where the contact hole is needed to be made in the small-pixel array is expanded, the minimum distance between the contact hole and the adjacent vertical driving phase is increased, the problem of short circuit between polysilicon layers in the small-pixel CCD is avoided, and the yield of the small-pixel CCD is improved.

Description

Technical Field

[0001] This invention belongs to the field of CCD technology and relates to a small-pixel CCD structure. Background Technology

[0002] CCDs (Charge Coupled Devices) are characterized by high sensitivity, low noise, and a large dynamic range, and are widely used in the aerospace field. With the rapid development of aerospace Earth imaging, CCD pixel sizes are decreasing to achieve high-resolution imaging. Consequently, the polysilicon size in the pixel area is also decreasing. Existing polysilicon designs for pixel areas cannot meet the requirements of polysilicon contact hole processes, reducing manufacturability and easily leading to interlayer short circuits in the polysilicon of these small-pixel CCDs, resulting in a significant drop in the yield rate of CCD chips. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a small-pixel CCD structure with high chip yield.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A small-pixel CCD structure includes a substrate with buried trenches and a plurality of vertical CCD driving gates. Each vertical CCD driving gate includes a plurality of vertical driving phases, each of which is arranged along a first direction. The substrate also has a plurality of channel resistors, each of which is arranged along a second direction perpendicular to the first direction. The vertical CCD driving gates have a plurality of metal leads arranged parallel to the channel resistors, and each metal lead is located directly above a channel resistor.

[0006] Below each metal lead of the vertical CCD drive gate, an expansion structure is provided. A contact hole is opened in the middle of the expansion structure. The contact hole is filled with metal. The metal lead is electrically connected to a vertical drive phase of the vertical CCD drive gate through the metal filled in the contact hole. The expansion structure is used to increase the width of the vertical drive phase in the area where the contact hole is opened, thereby increasing the minimum distance between the contact hole and the adjacent vertical drive phase.

[0007] Furthermore, the vertical CCD driving gate includes vertical driving phase CI1, vertical driving phase CI2, vertical driving phase CI3, and vertical driving phase CI4. The vertical CCD driving gate is provided with at least one first metal lead, at least one second metal lead, at least one third metal lead, and at least one fourth metal lead. An expansion structure is provided at the position directly below each first metal lead for each vertical driving phase CI1, at the position directly below each second metal lead for each vertical driving phase CI2, at the position directly below each third metal lead for each vertical driving phase CI3, and at the position directly below each fourth metal lead for each vertical driving phase CI4.

[0008] Furthermore, the expansion structure includes a first protrusion protruding outward on one side of the vertical drive phase and a second protrusion protruding outward on the other side of the vertical drive phase.

[0009] Furthermore, the vertical drive phase CI 1 and the vertical drive phase CI 3 are formed using primary polysilicon. The primary polysilicon has a first protrusion protruding outward on one side corresponding to the position where the contact hole will be formed, and a second protrusion protruding outward on the other side corresponding to the position where the contact hole will be formed.

[0010] Furthermore, on one side of the primary polysilicon, a first recessed portion is formed at the location where a contact hole will be formed for the adjacent vertical driving phase; on the other side of the primary polysilicon, a second recessed portion is formed at the location where a contact hole will be formed for the adjacent vertical driving phase.

[0011] The vertical driving phase CI2 and the vertical driving phase CI4 are formed using secondary polysilicon. During the formation process, the secondary polysilicon fills the first and second recesses on the side of the primary polysilicon, respectively. The secondary polysilicon filled in the first and second recesses forms the first and second protrusions that bulge outward, respectively. At the position where the secondary polysilicon and the primary polysilicon meet, the secondary polysilicon is provided with an overlapping structure covering the primary polysilicon.

[0012] Furthermore, the first protrusion and the second protrusion are symmetrically arranged on both sides of the vertical drive phase.

[0013] Furthermore, both the first protrusion and the second protrusion are isosceles trapezoidal structures that protrude outward from the side of the vertical drive phase.

[0014] Furthermore, the two base angles of the isosceles trapezoidal structure are 45°.

[0015] Furthermore, the contact hole is square, and the minimum distance between the four vertices of the square and the adjacent vertical drive phase is equal.

[0016] Furthermore, the pixel size in the small-pixel CCD structure is less than 10 μm.

[0017] In this invention, by adding an expansion structure to the area where contact holes need to be formed in the vertical driving phase, the entire small pixel array is expanded in the polysilicon area where contact holes need to be formed. This increases the minimum spacing between the contact holes and adjacent vertical driving phases, avoiding the problem of interlayer short circuits in polysilicon in small pixel CCDs and improving the yield of such small pixel CCDs. Using the structure of this invention, there is no need for a complete overhaul of the CCD manufacturing process; only minor adjustments to the existing CCD manufacturing process are required to achieve a good electrical connection between the metal leads and the vertical driving phase. Furthermore, since the expansion structure of each pixel in the entire small pixel array is consistent, it ensures that the response uniformity, transfer efficiency, and other characteristics of the small pixel CCD structure do not degrade. Attached Figure Description

[0018] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0019] Figure 1 This is a schematic diagram of the structure of a single pixel in a standard-sized CCD.

[0020] Figure 2 This is a schematic diagram of the structure of a single pixel in an existing small-pixel CCD structure.

[0021] Figure 3 This is a schematic diagram of one embodiment of a small-pixel CCD structure according to the present invention.

[0022] Figure 4 This is a schematic diagram of the structure of a small pixel in the small pixel CCD structure of the present invention.

[0023] Figure 5 for Figure 4 A cross-sectional view at point AA.

[0024] Figure 6 A schematic diagram of the structure after forming a single polysilicon layer when preparing contact holes for small pixels to be opened on the vertical drive phase CI 1.

[0025] Figure 7 A schematic diagram of the structure after forming a primary polysilicon layer when preparing contact holes for small pixels on the vertical drive phase CI2.

[0026] Figure 8 In order to be in Figure 7 The diagram shows the structure of secondary polycrystalline silicon formed on the basis of the above.

[0027] Figure 9 This is a schematic diagram of the CCD subarray structure.

[0028] The meanings of the labels in the attached diagram are as follows:

[0029] Substrate-100; Buried trench-101; Gate dielectric-102; Trench resistance-103; Vertical CCD drive gate-110; Vertical drive phase CI1-111; Vertical drive phase CI2-112; Vertical drive phase CI3-113; Vertical drive phase CI4-114; Primary polysilicon-121; Secondary polysilicon-122; Overlapping structure-122a; First metal lead-131; Second metal lead-132; Third metal lead-133; Fourth metal lead-134; Contact hole-140; Expanded structure-150; First protrusion-151; First bevel-151a; Second bevel-151b; Second protrusion-152; Third bevel-152a; Fourth bevel-152b; First recess-161; Second recess-162. Detailed Implementation

[0030] The following specific examples illustrate the implementation of the present invention. The illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0031] For example, to fabricate a contact hole 140 on secondary polysilicon 122, please refer to [link / reference]. Figure 1 This is the structure of a single pixel in a conventionally sized CCD structure. The pixel's size (i.e., the width of the vertical CCD drive gate 110 along the y-axis) is 10 μm. Contact holes 140 are formed on secondary polysilicon 122 by etching polysilicon. The minimum spacing between the contact holes 140 and the adjacent primary polysilicon 121 on both sides is D1. Due to the large pixel size, the area of ​​the secondary polysilicon 122 available for fabricating the contact holes 140 is large, and existing contact hole fabrication processes can meet the fabrication requirements.

[0032] Please see Figure 2 This is the structure of a single pixel in an existing small-pixel CCD structure. The pixel size is 7μm. Contact holes 140 are etched into the secondary polysilicon 122. The minimum spacing between the contact holes 140 and the adjacent primary polysilicon 121 on both sides is D2. (Comparison) Figure 1 and Figure 2It can be seen that, due to the significant reduction in the size of a single pixel in a small-pixel CCD, the widths of each primary polysilicon 121 and secondary polysilicon 122 also become significantly narrower. This results in a significant reduction in the minimum spacing D2 between the contact hole 140 and the adjacent vertical driving phase relative to D1. Consequently, the area of ​​the secondary polysilicon 122 available for fabricating the contact hole 140 is reduced. If the original process is still used to fabricate the contact hole 140, it is easy for the contact hole 140 to short-circuit with the adjacent primary polysilicon 121, thus causing the CCD chip to be scrapped.

[0033] The etching of contact holes 140 on primary polysilicon 121 is essentially the same as etching them on secondary polysilicon 122, where short circuits between contact holes 140 and adjacent secondary polysilicon 122 are also possible. To form contact holes 140 on both primary and secondary polysilicon 121 without altering the small pixel structure, the fabrication process must be adjusted. This inevitably increases the development cost of such small-sized CCDs, and the process adjustments can also introduce uncertainties to device performance, extending the development cycle.

[0034] Please see Figure 3 , Figure 3 This is a schematic diagram of one embodiment of a small-pixel CCD structure according to the present invention. In the small-pixel CCD structure of the present invention, the pixel size is less than 10 μm.

[0035] This embodiment of a small-pixel CCD structure includes a substrate 100, on which a buried trench 101 is disposed, and a plurality of vertical CCD driving gates 110 are disposed on the buried trench 101. Of course, a gate medium 102 is also disposed between the buried trench 101 and the vertical CCD driving gates 110. These are conventional CCD structures and are irrelevant to the improved structure of the small-pixel CCD in this invention, therefore they will not be described in detail. Each vertical CCD driving gate 110 includes a plurality of vertical driving phases, and each vertical driving phase is disposed along the x-axis direction (i.e., the first direction). In this embodiment, the vertical CCD driving gate 110 includes four vertical driving phases: vertical driving phase CI1 (111), vertical driving phase CI2 (112), vertical driving phase CI3 (113), and vertical driving phase CI4 (114). Of course, in other embodiments, the vertical CCD driving gate 110 may also include two or other numbers of vertical driving phases. The vertical drive phases CI 1 (111), CI 2 (112), CI 3 (113), and CI 4 (114) are arranged sequentially along the y-axis (i.e., the second direction).

[0036] The substrate 100 is further provided with a plurality of trench resistors 103, each of which is arranged along the y-axis. The vertical CCD drive gate 110 is provided with a plurality of metal leads, which are arranged parallel to the trench resistors 103, and each of the metal leads is located directly above a trench resistor 103; the width of the metal lead (i.e., the size of the metal lead in the x-axis direction) is slightly larger than the width of the trench resistor 103 (i.e., the size of the trench resistor 103 in the x-axis direction). In this embodiment, the vertical CCD drive gate 110 is provided with at least one first metal lead 131 for electrical connection with the vertical drive phase CI 1 (111), at least one second metal lead 132 for electrical connection with the vertical drive phase CI 2 (112), at least one third metal lead 133 for electrical connection with the vertical drive phase CI 3 (113), and at least one fourth metal lead 134 for electrical connection with the vertical drive phase CI 4 (114). The first metal lead 131, the second metal lead 132, the third metal lead 133 and the fourth metal lead 134 are arranged alternately along the y-axis.

[0037] An expansion structure 150 is provided below each metal lead of the vertical CCD driving gate 110. In this embodiment, an expansion structure 150 is provided at the position directly below each first metal lead 131 corresponding to the vertical driving phase CI 1 (111) of each vertical CCD driving gate 110, at the position directly below each second metal lead 132 corresponding to the vertical driving phase CI 2 (112) of each vertical CCD driving gate 110, at the position directly below each third metal lead 133 corresponding to the vertical driving phase CI 3 (113) of each vertical CCD driving gate 110, and at the position directly below each fourth metal lead 134 corresponding to the vertical driving phase CI 4 (114) of each vertical CCD driving gate 110. A contact hole 140 is provided in the middle of the expansion structure 150. The contact hole 140 is filled with metal, and the metal lead is electrically connected to a vertical driving phase of the vertical CCD driving gate 110 through the metal filled in the contact hole 140. The expansion structure 150 is used to increase the width of the vertical drive phase in the area where the contact hole 140 is opened along the y-axis, thereby increasing the minimum distance between the contact hole 140 and the adjacent vertical drive phase.

[0038] The expansion structure 150 may include a first protrusion 151 protruding outward on one side of the vertical drive phase and a second protrusion 152 protruding outward on the other side of the vertical drive phase; the first protrusion 151 and the second protrusion 152 may be symmetrically arranged on both sides of the vertical drive phase. In this embodiment, the first protrusion 151 and the second protrusion 152 are both isosceles trapezoidal structures protruding outward from the side of the vertical drive phase, and the two base angles of the isosceles trapezoidal structure are 45°. Taking the vertical driving phase CI 1 (111) as an example, since the two sides of the first protrusion 151 and the second protrusion 152 on the vertical driving phase CI 1 (111) are designed to be inclined at 45°, the expansion structure 150 is formed to protrude from both sides of the primary polysilicon at a 45° angle. This not only allows the primary polysilicon region where the expansion structure 150 is located to meet the fabrication requirements of the contact hole 140, but also allows control over the area of ​​the recessed region of the secondary polysilicon of the vertical driving phase CI 2 (112) and the vertical driving phase CI 4 (114) adjacent to the primary polysilicon of the vertical driving phase CI 1 (111), ensuring that the full-well capacity characteristics of the vertical driving phase CI 2 (112) and the vertical driving phase CI 4 (114) will not degrade. Therefore, the 45° angle is an optimal angle.

[0039] Since the contact hole 140 is generally a square hole, after the first protrusion 151 and the second protrusion 152 adopt the above-described isosceles trapezoidal structure, the minimum distance between the four vertices of the square and the adjacent vertical drive phases is equal. An embodiment is described below:

[0040] Please see Figure 4 This is a schematic diagram of the structure of a small pixel in the small pixel CCD structure of this embodiment. Figure 4The contact hole 140 of the small and medium-sized pixels is formed on the vertical drive phase CI 1 (111). A first protrusion 151 and a second protrusion 152 are respectively provided on both sides of the contact hole 140 on the vertical drive phase CI 1 (111). The first protrusion 151 has a first inclined surface 151a and a second inclined surface 151b forming a 45° angle with the axis of the vertical drive phase CI 1 (111); the second protrusion 152 has a third inclined surface 152a and a fourth inclined surface 152b forming a 45° angle with the axis of the vertical drive phase CI 1 (111). Among the four vertices of the contact hole 140, the minimum distance between the upper left vertex and the first inclined surface 151a is L1, the minimum distance between the upper right vertex and the second inclined surface 151b is L2, the minimum distance between the lower right vertex and the third inclined surface 152a is L3, and the minimum distance between the lower left vertex and the fourth inclined surface 152b is L4. Since the contact hole 140 is located in the middle of the expansion structure 150, it can be known that L1, L2, L3, and L4 are all equal, that is, the minimum distance between the contact hole 140 and the vertical drive phase CI 2 (112) and the vertical drive phase CI 4 (114) is L1. By... Figure 4 and Figure 2 Comparison shows that, Figure 4 At the same pixel size, the minimum spacing L1 between the contact hole 140 and the adjacent vertical drive phase is much larger than that between the contact hole 140 and the adjacent vertical drive phase. Figure 2 The minimum spacing D2 between the contact hole 140 and the adjacent vertical drive phase. This allows for electrical connection between the metal leads and the vertical drive phase CI 1 (111) without adjusting the fabrication process, and avoids the problem of interlayer short circuits in polysilicon for small-pixel CCDs.

[0041] Please see Figure 5 ,for Figure 4 A cross-sectional view along the AA direction at the connection point of the vertical drive phase CI 4 (114) and the vertical drive phase CI 1 (111) at the edge of the extended structure 150. When the vertical drive phase CI 4 (114) is at a low level and the vertical drive phase CI 1 (111) is at a high level, the charge signal stored under the vertical drive phase CI 4 (114) can be transferred to the potential well of the vertical drive phase CI 1 (111) under the action of the potential gradient, ensuring smooth signal transfer in the channel.

[0042] In the CCD fabrication process, the vertical driving phase CI 1 (111) and vertical driving phase CI 3 (113) are generally formed using primary polysilicon 121, while the vertical driving phase CI 2 (112) and vertical driving phase CI 4 (114) are formed using secondary polysilicon 122. When forming the vertical driving phase CI 1 (111) and vertical driving phase CI 3 (113) using primary polysilicon 121, a first protrusion 151 is formed on one side of the primary polysilicon 121 at the location where the contact hole 140 will be formed, and a second protrusion 152 is formed on the other side of the primary polysilicon 121 at the location where the contact hole 140 will be formed.

[0043] For example, please see Figure 6 When a small pixel is to form a contact hole 140 on the vertical driving phase CI 1 (111), the primary polysilicon 121 used to form the vertical driving phase CI 1 (111) has outwardly protruding first protrusion 151 and second protrusion 152 on both sides, respectively. The primary polysilicon 121 used to form the vertical driving phase CI 3 (113) has a normal strip structure, and the first protrusion 151 and second protrusion 152 are not formed on its sides. Of course, when a small pixel is to form a contact hole 140 on the vertical driving phase CI 3 (113), the primary polysilicon 121 used to form the vertical driving phase CI 3 (113) has outwardly protruding first protrusion 151 and second protrusion 152 on both sides, respectively. The primary polysilicon 121 used to form the vertical driving phase CI 1 (111) has a normal strip structure, and the first protrusion 151 and second protrusion 152 are not formed on its sides.

[0044] Please see Figure 7 When a contact hole 140 is to be formed on the vertical driving phase CI 2 (112) of a small pixel, a first recessed portion 161 is formed on the side of the primary polysilicon 121 used to form the vertical driving phase CI 1 (111) corresponding to the vertical driving phase CI 2 (112); a second recessed portion 162 is formed on the side of the primary polysilicon 121 used to form the vertical driving phase CI 3 (113) corresponding to the vertical driving phase CI 2 (112). Please refer to Figure 8During the fabrication of the secondary polysilicon 122 used to form the vertical driving phase CI 2 (112), a first recess 161 on one side of the primary polysilicon 121 and a second recess 162 on the other side of the primary polysilicon 121 are filled respectively. The secondary polysilicon 122 filled in the first recess 161 and the second recess 162 respectively forms an outwardly protruding first protrusion 151 and a second protrusion 152. At the position where the secondary polysilicon 122 connects to the primary polysilicon 121, the secondary polysilicon 122 is provided with an overlapping structure 122a covering the primary polysilicon 121. At each position where the secondary polysilicon 122 connects to the primary polysilicon 121, the width of the overlapping structure 122a is equal. For example, please refer to [further details omitted]. Figure 4 The width a1 of the overlapping structure 122a at the first protrusion 151 is equal to the width a2 of the overlapping structure 122a in the region outside the expansion structure 150.

[0045] Based on the above method, primary polycrystalline silicon 121 and secondary polycrystalline silicon are formed, and the first metal lead 131, the second metal lead 132, the third metal lead 133 and the fourth metal lead 134 are fabricated to make electrical contact with vertical driving phases CI1 (111), CI2 (112), CI3 (113) and CI4 (114) respectively. The resulting pixel structure can be as follows: Figure 9 The CCD subarray shown consists of four adjacent small pixels along the x-axis. Of course, four adjacent small pixels along the y-axis can also be considered as a CCD subarray.

[0046] based on Figure 9 The CCD subarray in the middle can be used to obtain, as shown in the example. Figure 3 The distribution of the entire small pixel array in the CCD structure shown demonstrates that by forming complementary polysilicon "bump" structures in the extended regions, the entire small pixel array is expanded in the polysilicon areas where contact holes 140 need to be fabricated. For example, in this embodiment, after adding the expansion structure 150 to the primary polysilicon 121 and secondary polysilicon 122 regions where contact holes 140 need to be fabricated in the 7μm pixel CCD structure, the minimum spacing between the contact holes 140 and the adjacent vertical driving phase still reaches the level of the prior art CCD structure with a pixel size of 10μm. This avoids the problem of interlayer short circuits in polysilicon in small pixel CCDs and improves the yield of such small pixel CCDs. The structure of this embodiment does not require a complete adjustment to the CCD fabrication process; only minor adjustments to the existing CCD fabrication process are needed to achieve a good electrical connection between the metal leads and the vertical driving phase. In addition, since the extended structure of each pixel in the entire small pixel array is consistent, it ensures that the response uniformity, transfer efficiency and other characteristics of the small pixel CCD structure will not degrade.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A small-pixel CCD structure, characterized in that: The device includes a substrate, on which buried trenches are formed, and a plurality of vertical CCD driving gates are formed on the buried trenches. Each vertical CCD driving gate includes a plurality of vertical driving phases, and each vertical driving phase is arranged along a first direction. The substrate also includes a plurality of channel resistors, each of which is arranged along a second direction perpendicular to the first direction. The vertical CCD driving gates are provided with a plurality of metal leads, which are arranged parallel to the channel resistors, and each metal lead is located directly above a channel resistor. Below each metal lead of the vertical CCD drive gate, an expansion structure is provided. A contact hole is opened in the middle of the expansion structure. The contact hole is filled with metal. The metal lead is electrically connected to a vertical drive phase of the vertical CCD drive gate through the metal filled in the contact hole. The expansion structure is used to increase the width of the vertical drive phase in the area where the contact hole is opened, thereby increasing the minimum distance between the contact hole and the adjacent vertical drive phase.

2. The small-pixel CCD structure according to claim 1, characterized in that: The vertical CCD driving grid includes vertical driving phases CI1, CI2, CI3, and CI4. At least one first metal lead, at least one second metal lead, at least one third metal lead, and at least one fourth metal lead are provided on the vertical CCD driving grid. An expansion structure is provided at the position directly below each first metal lead for each vertical driving phase CI1, at the position directly below each second metal lead for each vertical driving phase CI2, at the position directly below each third metal lead for each vertical driving phase CI3, and at the position directly below each fourth metal lead for each vertical driving phase CI4.

3. The small-pixel CCD structure according to claim 1, characterized in that: The expansion structure includes a first protrusion protruding outward on one side of the vertical drive phase and a second protrusion protruding outward on the other side of the vertical drive phase.

4. A small-pixel CCD structure according to claim 3, characterized in that: The vertical driving phase CI1 and the vertical driving phase CI3 are formed using primary polysilicon. The primary polysilicon has a first protrusion protruding outward on one side corresponding to the position where the contact hole will be formed, and a second protrusion protruding outward on the other side corresponding to the position where the contact hole will be formed.

5. A small-pixel CCD structure according to claim 4, characterized in that: On one side of the primary polysilicon, a first recessed portion is formed at the location where a contact hole will be made for the adjacent vertical driving phase; on the other side of the primary polysilicon, a second recessed portion is formed at the location where a contact hole will be made for the adjacent vertical driving phase. The vertical driving phase CI2 and vertical driving phase CI4 are formed using secondary polysilicon. During the formation process, the secondary polysilicon fills the first and second recesses on the side of the primary polysilicon, respectively. The secondary polysilicon filled in the first and second recesses forms the first and second protrusions that bulge outward, respectively. At the position where the secondary polysilicon and the primary polysilicon meet, the secondary polysilicon is provided with an overlapping structure covering the primary polysilicon.

6. A small-pixel CCD structure according to any one of claims 3 to 5, characterized in that: The first protrusion and the second protrusion are symmetrically arranged on both sides of the vertical drive phase.

7. A small-pixel CCD structure according to claim 6, characterized in that: Both the first protrusion and the second protrusion are isosceles trapezoidal structures that protrude outward from the side of the vertical drive phase.

8. A small-pixel CCD structure according to claim 7, characterized in that: The two base angles of the isosceles trapezoidal structure are 45°.

9. A small-pixel CCD structure according to claim 8, characterized in that: The contact hole is square, and the minimum distance between the four vertices of the square and the adjacent vertical drive phase is equal.

10. A small-pixel CCD structure according to claim 1, characterized in that: The pixel size in the small-pixel CCD structure is less than 10 μm.

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