Target structure

Abstract

The present invention relates to a target structure and a preparation method therefor. The target structure comprises at least two target layers and a connecting unit; the target layers are stacked in a first direction and are made of the same material; the connecting unit is located between two adjacent target layers; the connecting unit is connected to the adjacent target layers in the first direction; the connecting unit comprises a first connecting layer; the material of the first connecting layer is the same as that of the target layers; the first connecting layer is located in at least part of the area of the connecting unit; and the thermal conductivity of at least part of the connecting unit is less than that of the target layers. In the target structure of the present invention, by providing the connecting unit having a thermal conductivity not greater than that of the target layers, the heat conduction of the target structure in a longitudinal direction can be optimized during gradual evaporation from top to bottom, thereby avoiding the impact of heat accumulation in the longitudinal direction on the quality of a lower target structure, and improving the evaporation performance of the target structure and the final film-forming quality.

Description

A target structure Technical Field

[0001] This application relates to the field of vapor deposition technology, and in particular to a target structure. Background Technology

[0002] In existing evaporation coating processes, the target material used is generally a sintered, monolithic cylindrical target. However, during the top-to-bottom evaporation process of a conventional monolithic cylindrical target, only a portion of the heat can be transferred in the lateral direction to the upper surface layer of the target, while a large amount of heat is transferred downwards and accumulates in the longitudinal direction. Figure 1 shows a schematic diagram of the target structure. The heat accumulated in the longitudinal direction affects the physical properties of the lower, unevaporated target layer, thereby affecting the quality of the target and the quality and performance of the film formed based on the target. Summary of the Invention

[0003] Therefore, it is necessary to provide a target structure to address the problem that heat accumulates longitudinally during the evaporation coating process of existing targets, thus affecting the film quality.

[0004] To achieve the above objectives, in one aspect, the present invention provides a target structure comprising:

[0005] At least two target material layers are stacked along a first direction and are made of the same material;

[0006] A connecting unit is located between two adjacent target material layers. The connecting unit connects the adjacent target material layers in a first direction. The connecting unit includes a first connecting layer. The material of the first connecting layer is the same as that of the target material layers, and the first connecting layer is located in at least a portion of the connecting unit. The thermal conductivity of the connecting unit is less than that of the target material layers.

[0007] In one embodiment, the material density of the first connecting layer is less than the material density of the target layer.

[0008] In one embodiment, on a projection plane perpendicular to the first direction, the orthographic projection of the first connecting layer overlaps with the orthographic projection of the target layer.

[0009] In one embodiment, the connecting unit includes a first region and a second region. The first region is provided with the first connecting layer. On a projection plane perpendicular to the first direction, the orthographic projection area of ​​the first region is smaller than the orthographic projection area of ​​the target layer, and the thermal conductivity of the second region is smaller than the thermal conductivity of the target layer.

[0010] In one embodiment, the first connecting layer is annular in shape and connects to the edge of the target layer.

[0011] In one embodiment, the first connection layer includes a plurality of connection portions distributed in a ring-shaped interval.

[0012] In one embodiment, each of the target layers includes at least two sub-target portions made of the same material, adjacent sub-target portions are spliced ​​along the first direction, and a second connecting layer is provided between adjacent sub-target portions, the material of the second connecting layer being the same as that of the sub-target portions.

[0013] In one embodiment, each of the target material layers includes at least two sub-target material portions made of the same material, adjacent sub-target material portions are spliced ​​along a second direction perpendicular to the first direction, and a third connecting layer is provided between adjacent sub-target material portions, the material of the third connecting layer being the same as the material of the sub-target material portions.

[0014] In one embodiment, the thickness of the connecting unit is no more than one-tenth of the thickness of the target layer.

[0015] In one embodiment, the target layer has a non-planar irregular structure.

[0016] In this embodiment, the target structure comprises multiple target layers. These multiple target layers are stacked, and connecting units are provided between adjacent target layers. The thermal conductivity of the connecting units is lower than that of the target layers. Therefore, the amount of heat transferred in the first direction can be effectively reduced by the connecting units, thereby reducing heat accumulation in the longitudinal direction of the target structure. This avoids affecting the quality of the lower target structure, improving the evaporation performance and final film quality of the target structure. Simultaneously, during the top-to-bottom evaporation process of the target structure, the heat acting on the same target layer can be better conducted in the second direction, resulting in better film deposition during the heating and evaporation process. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 is a front view schematic diagram of a target structure provided in the prior art;

[0019] Figure 2 is a schematic diagram of the target structure provided in one embodiment;

[0020] Figure 3 is a schematic diagram of the front view of the target layer of the target structure provided in one embodiment;

[0021] Figure 4 is a front view schematic diagram of a first connecting layer of a target structure provided in one embodiment;

[0022] Figure 5 is a top view of another first connecting layer of the target structure provided in one embodiment;

[0023] Figure 6 is a front view schematic diagram of the third type of first connecting layer of the target structure provided in one embodiment;

[0024] Figure 7 is a front view schematic diagram of the fourth type of first connecting layer of the target structure provided in one embodiment;

[0025] Figure 8 is a top view of the fifth type of first connecting layer of the target structure provided in one embodiment;

[0026] Figure 9 is a top view of the sixth type of first connecting layer of the target structure provided in one embodiment;

[0027] Figure 10 is a top view of a target layer of a target structure provided in one embodiment;

[0028] Figure 11 is a schematic diagram of the main structure of a sub-target part in the target layer of Figure 10;

[0029] Figure 12 is a schematic diagram of the main structure of another sub-target material in the target material layer of Figure 10;

[0030] Figure 13 is a schematic diagram of the main structure of the third seed target part in the target layer of Figure 10;

[0031] Figure 14 is a top view schematic diagram of another target layer structure provided in one embodiment of the target structure;

[0032] Figure 15 is a schematic diagram of the main structure of the target layer in Figure 14;

[0033] Figure 16 is a top view schematic diagram of a third type of target material layer structure provided in one embodiment;

[0034] Figure 17 is a schematic diagram of the main structure of the target layer in Figure 16.

[0035] Explanation of reference numerals in the attached figures:

[0036] 1-Target layer, 11-Sub-target part, 2-Connecting unit, 21-First connecting layer, 211-Connecting part, 22-First region, 23-Second region. Detailed Implementation

[0037] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0039] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0040] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0041] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0042] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0043] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0044] Referring to Figure 2, this application embodiment provides a target structure, which includes at least two target layers 1 and connecting units 2. The at least two target layers 1 are stacked along a first direction (indicating longitudinal direction), and all target layers 1 are made of the same material. The connecting units 2 are located between adjacent target layers 1. The connecting units 2 connect adjacent target layers 1 along the first direction. The connecting unit 2 includes a first connecting layer 21, the first connecting layer 21 being made of the same material as the target layers 1, and the first connecting layer 21 being located in at least a portion of the connecting unit 2. The thermal conductivity of the connecting unit 2 is lower than that of the target layers 1.

[0045] Specifically, the target layer 1 includes a metal target, a metal oxide target, a ceramic target, or other suitable target material. The thickness of the target layer 1 can range from, for example, 1 mm to 10 mm. It should be noted that, while meeting the performance requirements of the target structure, the specific number of target layers 1 can be selected according to the actual situation and is not limited here.

[0046] Referring to Figure 3, the target layer 1 can be cylindrical, rectangular, or other suitable planar structures. By setting the target layer 1 to a planar structure with uniform and consistent thickness, such as a cylindrical or rectangular shape, it is possible to ensure the formation of a film layer with uniform thickness during the evaporation coating process, thereby guaranteeing the uniformity of the coating and improving the coating quality. In some embodiments, the target layer 1 can also be set to a non-planar irregular structure. In some coating processes where different film thicknesses are required in different areas, the shape of the target layer 1 can be designed as a non-planar irregular structure according to the actual coating requirements, so as to achieve the evaporation coating of film layers with different thicknesses in different areas.

[0047] Furthermore, for the connecting unit 2, the thermal conductivity of the connecting unit 2 located between the target layers 1 is less than that of the target layer 1, thereby providing thermal barrier in the first direction, reducing the heat conduction from the upper target to the lower target, and avoiding the influence of the lower target in the subsequent coating process, such as excessive heat accumulation, which would cause changes in the properties of the lower target and thus affect the electrical and optical properties of the subsequently deposited film.

[0048] The first connecting layer 21 is made of the same material as the target layer 1, which does not affect the quality of the coating and thus ensures the continuity of the coating.

[0049] Please refer to Figure 4. In some embodiments, on the projection plane perpendicular to the first direction, the orthographic projection of the first connecting layer 21 overlaps with the orthographic projection of the target layer 1, for example, partially or completely. For example, the orthographic projection areas of the first connecting layer 21 and the target layer 1 are equal, further reducing the impact on the coating uniformity.

[0050] Simultaneously, the material density of the first connecting layer 21 is less than that of the target layer 1. Lower material density results in lower thermal conductivity and poorer thermal performance. Therefore, since the thermal conductivity of the first connecting layer 21 is less than that of the target layer 1, the thermal conductivity of the connecting unit 2 is also less than that of the target layer 1. This effectively reduces heat conduction in the first direction, prevents continuous heat accumulation in the first direction, and avoids affecting the properties of the underlying target structure.

[0051] Specifically, the shape of the first connecting layer 21 can be set to be the same as that of the target layer 1. For example, if the target layer 1 has a planar structure such as a column or rectangle, the shape of the first connecting layer 21 can also be set to a planar structure such as a column or rectangle. Similarly, if the target layer 1 has a non-planar irregular shape, the shape of the first connecting layer 21 can also be set to a non-planar irregular shape. By setting the shape of the first connecting layer 21 to be the same as that of the target layer 1, adjacent target layers 1 can be effectively connected through the first connecting layer 21.

[0052] At this point, the area between adjacent target layers 1 can be completely filled by the first connecting layer 21, thereby facilitating uniform overall thickness of the target structure at all locations in the second direction and reducing the impact on coating uniformity. Simultaneously, this also effectively reduces the difficulty of the target structure fabrication process.

[0053] Meanwhile, please refer to Figure 5. When the first connecting layer 21 is included in the connecting part 2 and the orthographic projection of the first connecting layer 21 overlaps with the orthographic projection of the target layer 1 on the projection plane perpendicular to the first direction, the material density at each position of the first connecting layer 21 can be kept consistent, which helps to ensure the uniformity of the coating and further reduce the difficulty of the target structure preparation process.

[0054] Of course, in some embodiments, when the connecting part 2 includes a first connecting layer 21, and the orthographic projection of the first connecting layer 21 overlaps with the orthographic projection of the target layer 1 on the projection plane perpendicular to the first direction, the material density of the first connecting layer 21 can also be set to gradually distribute from the middle region to the edge region in the second direction, or the material density of the first connecting layer 21 can be gradually distributed in the first direction, in order to meet special structural design and coating requirements. For example, in some coating processes with high requirements for film thickness uniformity, the influence of the connecting layer on the film thickness uniformity can be further reduced.

[0055] Please refer to Figure 6. In some embodiments, the connection unit 2 includes a first region 22 and a second region 23.

[0056] A first connecting layer 21 is provided in the first region 22. The material of the first connecting layer 21 is the same as that of the target layer 1, thereby ensuring the continuity of the coating.

[0057] Specifically, the material density of the first connecting layer 21 within the first region 22 can be greater than, equal to, or less than the material density of the target layer 1, provided that the overall thermal conductivity of the connecting unit 2 formed by the first region 22 and the second region 23 is less than the thermal conductivity of the target layer 1. For example, the material density of the first connecting layer 21 is less than that of the target layer 1. By setting the material density of the first connecting layer 21 to be less than that of the target layer 1, the thermal conductivity of the connecting unit 2 is reduced, thus optimizing the heat conduction of the target structure in the first direction. Alternatively, the material density of the first connecting layer 21 can be greater than or equal to that of the target layer 1, but the area of ​​the first region containing the first connecting layer 21 can be adjusted to ensure that the overall thermal conductivity of the connecting unit 2 formed by the first region 22 and the second region 23 is less than that of the target layer 1. This reduces the heat accumulation of the target structure in the longitudinal direction and avoids affecting the quality of the underlying target structure.

[0058] On a projection plane perpendicular to the first direction, the orthographic projection area of ​​the first region 22 is smaller than the orthographic projection area of ​​the target layer 1, thereby allowing the first connecting layer 21 to fill a portion of the area between adjacent target layers 1. The area without the first connecting layer 21 can form the second region 23.

[0059] The thermal conductivity of the second region 23 is lower than that of the target layer 1. For example, a gas is provided in the second region 23. Since the thermal conductivity of the gas is lower than that of the solid, the thermal conductivity of the second region 23 of the connecting unit 2 is lower than that of the target layer 1. Therefore, during heat conduction, the accumulation of heat in the first direction can be reduced by the gas in the second region 23, thereby effectively improving the heat conduction of the target structure in the first direction.

[0060] Please refer to Figures 7 and 8. While meeting the performance requirements of the target structure, the second region 23 can be either a closed or open region. No connecting layer material is provided within the second region 23; therefore, the gas within the second region 23 can be any gas that meets actual needs, as long as it achieves the effect of thermal barrier in the first direction.

[0061] As an example, when the second region 23 is a closed region, the gas within the second region 23 can be an inert gas such as nitrogen or argon. Inert gases have stable properties and can prevent reactions with the target layer 1 and the first connecting layer 21 during the evaporation coating process, thus ensuring the coating quality. Alternatively, the gas within the second region 23 can also be air.

[0062] When the second region 23 is an open region, meaning it is connected to the ambient atmosphere, the gas within the second region 23 remains consistent with the ambient atmosphere during the evaporation coating process. Generally, the evaporation chamber is in a vacuum environment during evaporation. In this case, the gas within the second region 23 is the coating gas. The consistent atmosphere inside and outside the second region 23 when it is an open region effectively prevents pressure differential issues from damaging the target structure during operation.

[0063] In some embodiments, the first connecting layer 21 is annular in shape. The first connecting layer 21 connects to the edge of the target layer 1, thereby making the second region 23 of the connecting unit sufficiently large, ensuring that the area with low thermal conductivity is sufficiently large, and effectively reducing heat accumulation in the first direction. Furthermore, the middle region of the connecting unit is entirely filled with gas, thus facilitating improved coating uniformity.

[0064] Furthermore, the first connecting layer 21 may include a plurality of connecting portions 211 distributed in a ring-shaped interval. In this case, a non-enclosed second region can be formed, thereby effectively avoiding the target structure from breaking due to the thermal expansion of the gas in the second region 23 during the vapor deposition process.

[0065] In some embodiments, the first connecting layer 21, which is arranged in a ring shape, may be provided with at least one through hole that penetrates the first connecting layer 21 in a first direction, or the first connecting layer 21 may be provided with at least one through hole that penetrates the first connecting layer 21 in a second direction, so as to form a non-closed second region, thereby reducing the risk of target material structure breakage.

[0066] Referring to Figure 9, in some embodiments, the connecting unit 2 includes a first region 22 and a second region 23. A first connecting layer 21 is provided within the first region 22. When the projected area of ​​the first connecting layer 21 on a projection plane perpendicular to the first direction is smaller than the projected area of ​​the target layer 1, multiple first connecting layers 21 can be provided between adjacent target layers 1. Furthermore, the material density of the multiple first connecting layers 21 gradually varies from the center to both sides, thereby increasing design flexibility and satisfying different design requirements while ensuring the thermal insulation and connection performance of the first connecting layers 21.

[0067] Referring to Figures 10 to 13, in some embodiments, each target layer 1 includes at least two sub-target portions 11 made of the same material. Adjacent sub-target portions 11 are spliced ​​along a first direction, and a second connecting layer (not shown) is also provided between adjacent sub-target portions 11. The material of the second connecting layer is the same as the material of the sub-target portions 11.

[0068] By setting the target layer 1 to be spliced ​​from sub-target parts 11 in the first direction, and a second connecting layer is provided between adjacent sub-target parts 11, the splicing structure in the first direction can effectively alleviate the problem of cracking caused by thermal stress in the target layer 1 during the evaporation coating process.

[0069] For example, the material density of the second connecting layer is the same as that of the target layer 1. By setting the material density of the second connecting layer to be the same as that of the target layer 1, the consistency of density in the first direction ensures the uniformity and quality of the coating.

[0070] When the target layer 1 is spliced ​​together by multiple sub-target parts 11 along the first direction, the specific number and shape of the sub-target parts 11 can be selected according to the actual situation, provided that the performance of the target layer 1 is met. For example, the shape of the sub-target parts 11 can be triangular, multi-curved, stepped, or other suitable shapes, which can meet different design and coating requirements.

[0071] Referring to Figures 14 to 17, in some embodiments, each target layer 1 includes at least two sub-target portions 11 made of the same material, and adjacent sub-target portions 11 are spliced ​​along a second direction perpendicular to the first direction. A third connecting layer (not shown) is provided between adjacent sub-target portions 11. The material of the third connecting layer is the same as the material of the sub-target portions 11.

[0072] By setting the target layer 1 to be spliced ​​from the sub-target parts 11 in the second direction, and setting a third connecting layer between adjacent sub-target parts 11, the tightness of the splicing of the target layer 1 in the second direction is ensured. The splicing structure in the second direction can also effectively alleviate the problem of cracking caused by thermal stress in the target layer 1 during the evaporation coating process.

[0073] When the target layer 1 is spliced ​​together by multiple sub-target parts 11 along the second direction, the specific number and shape of the sub-target parts 11 can be selected according to the actual situation while satisfying the performance of the target layer 1. When the shape of the sub-target parts 11 is fan-shaped, the target layer 1 can be spliced ​​together by two fan-shaped sub-target parts 11 with a central angle of 180 degrees, or by three fan-shaped sub-target parts 11 with a central angle of 120 degrees, or by four fan-shaped sub-target parts 11 with a central angle of 90 degrees, thereby meeting different design and coating requirements.

[0074] For example, the material density of the third connecting layer is the same as that of the first connecting layer 21. By setting the material density of the third connecting layer to be the same as that of the target layer 1, the consistency of density in the second direction ensures the uniformity and quality of the coating.

[0075] In some embodiments, each of the plurality of target layers 1 has the same configuration. It should be noted that the same configuration here means that the plurality of target layers 1 are all integral structures and each target layer 1 has the same shape; or each target layer 1 is spliced ​​together from sub-target parts 11, and the number, shape and splicing method of the sub-target parts 11 in each target layer 1 are the same, that is, the structural composition of the target layers 1 is the same. By setting each target layer 1 to have the same configuration, the uniformity of the coating is ensured.

[0076] In other embodiments, at least two of the multiple target layers 1 have different configurations. It should be noted that different configurations here refer to the following: the target layers 1 may all be integral structures, in which case at least two target layers 1 have different shapes; or the target layer 1 may be composed of multiple sub-target parts 11 spliced ​​together, in which case the number, shape, and splicing method of the sub-target parts in at least two target layers 1 are different; or the target layer 1 may have both an integral structure and a configuration composed of multiple sub-target parts 11 spliced ​​together, meaning at least two target layers 1 have different structural compositions. By setting different configurations for the target layers 1, greater design flexibility is provided, allowing the configuration and arrangement of the target layers 1 to be adjusted according to specific application requirements, thereby achieving higher film quality and performance.

[0077] In some embodiments, the thickness of the connecting unit 2 is no more than one-tenth of the thickness of the target layer 1. By controlling the thickness of the connecting unit 2 to be no more than one-tenth of the thickness of the target layer 1, heat transfer is optimized while avoiding the impact of the connecting unit 2 on the film formation quality when used as an evaporation coating material. This also reduces production costs. Furthermore, by adjusting the thickness of the connecting unit 2, the heat conduction performance can be further optimized. The specific thickness of the first connecting layer 21 can be selected according to the actual situation, provided that the target structure performance is met. This is not limited here.

[0078] The target structure in this embodiment includes multiple target layers 1 stacked together. A connecting unit 2 is provided between adjacent target layers 1, and the thermal conductivity of the connecting unit 2 is lower than that of the target layer 1. Therefore, the continuous accumulation of heat in the first direction can be effectively reduced, thereby optimizing the heat conduction of the target structure in the first direction. This avoids the heat accumulation affecting the quality of the lower target structure, improving the evaporation performance and final film quality of the target structure. Simultaneously, during the top-down evaporation coating process, the heat acting on the same target layer 1 can be better conducted in the second direction, resulting in better film deposition of the target structure during the heating and evaporation process.

[0079] In the description of this specification, references to terms such as "some embodiments," "other embodiments," and "ideal embodiments" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0080] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features of the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0081] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A target structure, characterized in that, include: At least two target material layers are stacked along a first direction and are made of the same material; A connecting unit is located between two adjacent target material layers. The connecting unit connects the adjacent target material layers in a first direction. The connecting unit includes a first connecting layer. The material of the first connecting layer is the same as that of the target material layers, and the first connecting layer is located in at least a portion of the connecting unit. The thermal conductivity of the connecting unit is less than that of the target material layers.

2. The target structure of claim 1, wherein The material density of the first connecting layer is less than that of the target layer.

3. The target structure of claim 2, wherein, On a projection plane perpendicular to the first direction, the orthographic projection of the first connecting layer overlaps with the orthographic projection of the target layer.

4. The target structure of claim 1, wherein, The connecting unit includes a first region and a second region. The first region is provided with the first connecting layer. On a projection plane perpendicular to the first direction, the orthographic projection area of ​​the first connecting layer is smaller than the orthographic projection area of ​​the target material layer. The thermal conductivity of the second region is smaller than the thermal conductivity of the target material layer.

5. The target structure of claim 4, wherein, The first connecting layer is annular in shape and connects to the edge of the target layer.

6. The target structure of claim 5, wherein, The first connecting layer includes a plurality of connecting portions distributed in a ring-shaped interval.

7. The target structure of claim 1, wherein Each of the target material layers includes at least two sub-target material portions made of the same material. Adjacent sub-target material portions are spliced ​​together along the first direction, and a second connecting layer is provided between adjacent sub-target material portions. The material of the second connecting layer is the same as that of the sub-target material portions.

8. The target structure of claim 1, wherein, Each of the target material layers includes at least two sub-target material portions made of the same material. Adjacent sub-target material portions are spliced ​​together along a second direction perpendicular to the first direction, and a third connecting layer is provided between adjacent sub-target material portions. The material of the third connecting layer is the same as that of the sub-target material portions.

9. The target structure of claim 1, wherein, The thickness of the connecting unit is no more than one-tenth of the thickness of the target layer.

10. The target structure of claim 1, wherein The target layer can be cylindrical, rectangular, or non-planar irregularly shaped.

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