Planetary plate and graphite tray

Abstract

The invention provides a planetary plate and a graphite tray, and belongs to the technical field of semiconductor preparation. The planetary plate comprises a base plate and a supporting plate. The base disc is coaxially connected with the supporting disc, and the outer diameter of the base disc is not smaller than that of the supporting disc; a plurality of annular steps are arranged on the face, back on to the base disc, of the supporting disc, the annular steps are concentrically arranged, the heights of the annular steps are increased or decreased one by one in the radial direction of the supporting disc, and the height of the annular steps is the size of the annular steps in the axial direction of the supporting disc. According to the invention, the heating uniformity of the substrate can be effectively improved, so that the in-wafer wavelength uniformity of the prepared epitaxial wafer is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor preparation, and in particular relates to a planetary disk and a graphite tray. Background Art

[0002] Micro Light Emitting Diode (Micro LED) has the advantages of high resolution, high color saturation, and fast response speed. It has been widely used in the display field, optical communication field, biological field, and medical field.

[0003] In the related art, during the preparation process of micro-LED chips, metal organic chemical vapor deposition equipment is required to prepare epitaxial wafers. The graphite tray is an important component of the metal organic chemical vapor deposition equipment, which is equipped with multiple planetary disks to support the substrate so as to grow the epitaxial layer on the substrate to obtain the epitaxial wafer.

[0004] However, since the growth of epitaxial wafers is often heteroepitaxial growth (the epitaxial layer and the substrate are made of different materials), there are differences in lattice constants and thermal expansion coefficients between the substrate and the epitaxial layer. As a result, during the epitaxial growth process, large stresses are generated between the substrate and the epitaxial layer due to lattice differences and thermal mismatches, and accumulate at the interface between the substrate and the epitaxial layer, causing the substrate to warp at the edges due to the tensile stress of the epitaxial layer, that is, a gap appears between the edge of the substrate and the planetary disk, which ultimately leads to uneven heating. Summary of the invention

[0005] The disclosed embodiment provides a planetary disk and a graphite tray, which can effectively improve the heating uniformity of the substrate, thereby ensuring the wavelength uniformity within the prepared epitaxial wafer. The technical solution is as follows:

[0006] In a first aspect, an embodiment of the present disclosure provides a planetary disk, which is applied to a graphite tray, and includes a base disk and a support disk;

[0007] The base plate is coaxially connected to the support plate, and the outer diameter of the base plate is not less than the outer diameter of the support plate;

[0008] The support plate has a plurality of annular steps on a side facing away from the base plate. The annular steps are arranged concentrically. In the radial direction of the support plate, the height of each annular step increases or decreases one by one. The height of the annular step is the dimension of the annular step in the axial direction of the support plate.

[0009] In an implementation of the present disclosure, in the radial direction of the support disk, the height of each of the annular steps is an arithmetic progression; or,

[0010] In the radial direction of the support disk, the height of each of the annular steps is a geometric progression.

[0011] In an implementation of the present disclosure, the height of the annular step is 150-250 nm.

[0012] In an implementation of the present disclosure, the sum of the heights of the annular steps is 1.8-2.2 μm.

[0013] In an implementation of the present disclosure, in the radial direction of the support disk, the width of each of the annular steps increases or decreases one by one, and the height of the annular step is the dimension of the annular step in the radial direction of the support disk.

[0014] In an implementation of the present disclosure, in the radial direction of the support disk, the width of each of the annular steps is an arithmetic progression; or,

[0015] In the radial direction of the support disk, the width of each of the annular steps is a geometric progression.

[0016] In an implementation of the present disclosure, the width of the annular step is no greater than 250 μm.

[0017] In an implementation of the present disclosure, the annular step closest to the outer edge of the support plate among the annular steps is an edge step, and the outer edge of the edge step on a side facing away from the base plate is arc-shaped.

[0018] In an implementation of the present disclosure, the annular step closest to the outer edge of the support plate among the annular steps is a central step, and the area surrounded by the central step is a plane.

[0019] In a second aspect, an embodiment of the present disclosure provides a graphite tray, the graphite tray comprising a main tray body, a cover, and a plurality of planetary trays as described in the first aspect;

[0020] The cover is attached to one side of the main disk body, and the cover has a plurality of accommodating holes arranged at intervals from each other, and the accommodating holes correspond to the planetary disks one by one;

[0021] The planetary disk is located in the corresponding accommodating hole.

[0022] The beneficial effects brought by the technical solution provided by the embodiments of the present disclosure include at least:

[0023] The planetary disk provided in the embodiment of the present disclosure includes a base disk and a support disk, wherein the support disk is used to support the substrate, and the base plate provides a foundation for the support disk to ensure the stability of the support disk, which is conducive to the stable support of the substrate by the support disk. The side of the support disk facing away from the base disk has a plurality of annular steps, that is, the side of the support disk used to support the substrate has a plurality of annular steps. Since the annular steps are concentrically arranged, and the heights of the annular steps increase or decrease one by one in the radial direction of the support disk, the substrate support surface formed by the annular steps is generally convex in the middle or concave in the middle. In this way, the substrate support surface formed by each annular step can match the edge warping generated by the substrate, thereby effectively reducing the gap between the edge of the substrate and the planetary disk, which is conducive to improving the heating uniformity of the substrate, and then ensuring the intra-chip wavelength uniformity of the prepared epitaxial wafer.

[0024] That is to say, the planetary disk provided in the embodiment of the present disclosure, by arranging a plurality of annular steps on the side of the support disk facing away from the base disk, enables the substrate supporting surface formed by each annular step to match the edge warping produced by the substrate, thereby effectively reducing the gap between the edge of the substrate and the planetary disk, which is beneficial to improving the heating uniformity of the substrate, and further ensuring the in-wafer wavelength uniformity of the prepared epitaxial wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 is a schematic diagram of the structure of a planetary disk provided by an embodiment of the present disclosure;

[0027] Figure 2 is a cross-sectional view of the planetary disk provided by an embodiment of the present disclosure in the AA direction;

[0028] Figure 3 is a schematic structural diagram of a graphite tray provided in an embodiment of the present disclosure;

[0029] Figure 4 It is a cross-sectional view taken along the AA direction of the graphite tray provided in an embodiment of the present disclosure.

[0030] The symbols in the figure mean the following:

[0031] 10. Base plate;

[0032] 20. Support plate;

[0033] 210, circular step; 211, edge step; 212, center step;

[0034] 100. Main plate body;

[0035] 1100, air flow channel;

[0036] 200, covering parts;

[0037] 2100, receiving hole; 2200, sub-covering sheet; 2300, positioning protrusion;

[0038] 300, planetary disk;

[0039] 400, first mounting member;

[0040] 500. Second mounting member. DETAILED DESCRIPTION

[0041] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.

[0042] Compared with traditional light emitting diodes (LEDs), micro light emitting diodes (Micro LEDs) are very small, reaching less than 50μm. Micro LEDs have the advantages of high resolution, high color saturation, and fast response speed, and are widely used in display, optical communication, biological, and medical fields.

[0043] In the related art, during the preparation process of micro-LED chips, metal organic chemical vapor deposition equipment is required to prepare epitaxial wafers. The graphite tray is an important component of the metal organic chemical vapor deposition equipment, which is equipped with multiple planetary disks to support the substrate so as to grow the epitaxial layer on the substrate to obtain the epitaxial wafer.

[0044] However, since the growth of epitaxial wafers is often heteroepitaxial growth, there are differences in lattice constants and thermal expansion coefficients between the substrate and the epitaxial layer. Taking sapphire as the substrate and GaN as the example, in terms of lattice constants, sapphire: a = 0.4759 / c = 1.2991, GaN: a = 0.3189 / c = 0.5185, and in terms of thermal expansion coefficients, sapphire: a = 7.30 / c = 8.50, GaN: a = 5.59 / c = 3.17. Therefore, during the epitaxial growth process, large stress will be generated between the substrate and the epitaxial layer due to lattice differences and thermal mismatch, and accumulated at the interface between the substrate and the epitaxial layer, so that the substrate is subjected to the tensile stress of the epitaxial layer and the edge warps, that is, a gap appears between the edge of the substrate and the planetary disk, which ultimately leads to uneven heating.

[0045] In order to solve the above technical problems, an embodiment of the present disclosure provides a planetary disk, which is applied to a graphite tray. Figure 1 is a schematic diagram of the structure of the planetary disk, see Figure 1 In this embodiment, the planetary disk includes a base disk 10 and a support disk 20.

[0046] Figure 2 This is the AA direction cross-sectional view of the planetary disk, combined with Figure 2 The base plate 10 is coaxially connected to the support plate 20, and the outer diameter of the base plate 10 is not less than the outer diameter of the support plate 20. The support plate 20 has a plurality of annular steps 210 on a side facing away from the base plate 10, and each annular step 210 is arranged concentrically. In the radial direction of the support plate 20, the height of each annular step 210 increases or decreases one by one, and the height of the annular step 210 is the size of the annular step 210 in the axial direction of the support plate 20.

[0047] The planetary disk provided by the embodiment of the present disclosure includes a base disk 10 and a support disk 20, wherein the support disk 20 is used to support the substrate, and the base plate provides a foundation for the support disk 20 to ensure the stability of the support disk 20, which is conducive to the stable support of the substrate by the support disk 20. The side of the support disk 20 facing away from the base disk 10 has a plurality of annular steps 210, that is, the side of the support disk 20 used to support the substrate has a plurality of annular steps 210. Since the annular steps 210 are arranged concentrically, and the height of each annular step 210 increases or decreases one by one in the radial direction of the support disk 20, the substrate support surface formed by each annular step 210 is generally convex in the middle or concave in the middle. In this way, the substrate support surface formed by each annular step 210 can match the edge warping generated by the substrate, thereby effectively reducing the gap between the edge of the substrate and the planetary disk, which is conducive to improving the heating uniformity of the substrate, and thus ensuring the wavelength uniformity within the prepared epitaxial wafer.

[0048] That is to say, the planetary disk provided in the embodiment of the present disclosure, by arranging a plurality of annular steps 210 on the side of the support disk 20 facing away from the base disk 10, enables the substrate supporting surface formed by each annular step 210 to match the edge warping produced by the substrate, thereby effectively reducing the gap between the edge of the substrate and the planetary disk, which is beneficial to improving the heating uniformity of the substrate, and further ensuring the in-wafer wavelength uniformity of the prepared epitaxial wafer.

[0049] In this embodiment, the planetary disk is an integrated structural component, the main body of the planetary disk is graphite, and the surface of the graphite is provided with a silicon carbide surface layer.

[0050] In the above implementation, the planetary disk is used to support the substrate and transfer the temperature to the substrate to ensure that the heat received by the substrate is uniform. The integrated planetary disk can not only ensure the structural strength of the planetary disk, but also improve the manufacturing efficiency of the planetary disk.

[0051] In some examples, in the radial direction of the support plate 20 , the height of each annular step 210 is an arithmetic progression.

[0052] In the above implementation, the height of each annular step 210 increases one by one in the form of an arithmetic progression, or the height of each annular step 210 decreases one by one in the form of an arithmetic progression. In this way, the height of each annular step 210 can be increased or decreased in a specific rule, so that the height of each annular step 210 can be adjusted according to different situations, thereby reducing the difficulty of adjustment and improving the efficiency of adjustment.

[0053] In other examples, in the radial direction of the support plate 20 , the height of each annular step 210 is a geometric progression.

[0054] In the above implementation, the height of each annular step 210 increases one by one in the form of a geometric progression, or the height of each annular step 210 decreases one by one in the form of a geometric progression. In this way, the height of each annular step 210 can be increased or decreased in a specific pattern, so that the height of each annular step 210 can be adjusted according to different situations, thereby reducing the difficulty of adjustment and improving the adjustment efficiency.

[0055] Of course, in other embodiments, the height of each annular step 210 can also be irregularly increased or decreased one by one by any amplitude, and the present disclosure does not limit this.

[0056] Exemplarily, the height of the annular step 210 is 150-250 nm.

[0057] In the above implementation, the height of the annular step 210 reflects to a certain extent whether the substrate support surface formed by each annular step 210 is flat or steep. By designing the height of the annular step 210 to the above value, it is possible to ensure that the curvature of the substrate support surface formed by each annular step 210 matches the edge warping generated by the substrate. If the height of the annular step 210 is too small, the curvature of the substrate support surface formed by each annular step 210 is too small, and vice versa, the curvature of the substrate support surface formed by each annular step 210 is too large.

[0058] In this embodiment, the height of the annular step 210 is 200 nm. Of course, in other embodiments, the height of the annular step 210 can also be selected from other values ​​within the above numerical range, and the present disclosure does not limit this.

[0059] Exemplarily, the sum of the heights of the annular steps 210 is 1.8-2.2 μm.

[0060] In the above implementation, the sum of the heights of the annular steps 210 is the sum of the heights of all the annular steps 210, that is, the height difference between the highest point of the support plate 20 and the lowest point of the support plate 20. This value reflects to a certain extent the degree of edge warping of the substrate that can be matched by the substrate support surface formed by each annular step 210.

[0061] In this embodiment, the total height of each annular step 210 is 2 μm.

[0062] See also Figure 2 , the sum of the heights of the annular steps 210 is B'. In the direction from the outer edge of the support plate 20 to the middle, the heights of the annular steps 210 are α, β, γ, δ, ε, etc., that is, B'=α+β+γ+δ+ε+... The range of α, β, γ, δ, ε... is 0±200nm. When the value is positive, each annular step 210 is convex, and when the value is negative, each annular step 210 is concave. The total height difference of the support plate 20 is H', H'≥B', and the range of H' is 0±2μm. When the value is positive, it means that the middle of the support plate 20 is convex, and when the value is negative, it means that the middle of the support plate 20 is concave (see Figure 2 ).

[0063] In this embodiment, in the radial direction of the support disk 20 , the widths of the annular steps 210 increase or decrease one by one, and the height of the annular step 210 is the size of the annular step 210 in the radial direction of the support disk 20 .

[0064] In the above implementation, by adjusting the width of each annular step 210, the curvature of the substrate support surface formed by each annular step 210 can be adjusted. When the height of each annular step 210 increases or decreases to a certain extent, the greater the width of each annular step 210 increases, the flatter the substrate support surface formed by each annular step 210, and vice versa.

[0065] In some examples, in the radial direction of the support plate 20 , the width of each annular step 210 is an arithmetic progression.

[0066] In the above implementation, the width of each annular step 210 increases one by one in the form of an arithmetic progression, or the width of each annular step 210 decreases one by one in the form of an arithmetic progression. In this way, the width of each annular step 210 can be increased or decreased in a specific rule, so that the width of each annular step 210 can be adjusted according to different situations, thereby reducing the difficulty of adjustment and improving the efficiency of adjustment.

[0067] In some other examples, in the radial direction of the support plate 20 , the width of each annular step 210 is a geometric progression.

[0068] In the above implementation, the width of each annular step 210 increases one by one in the form of a geometric progression, or the width of each annular step 210 decreases one by one in the form of a geometric progression. In this way, the width of each annular step 210 can be increased or decreased in a specific rule, so that the width of each annular step 210 can be adjusted according to different situations, thereby reducing the difficulty of adjustment and improving the adjustment efficiency.

[0069] Of course, in other embodiments, the width of each annular step 210 can also be irregularly increased or decreased one by one by any amplitude, and the present disclosure does not limit this.

[0070] Exemplarily, the width of the annular step 210 is no greater than 250 μm.

[0071] See also Figure 2 The sum of the widths of the annular steps 210 is A'. In the direction from the outer edge to the middle of the support plate 20, the heights of the annular steps 210 are a, b, c, d, etc., that is, A'=a+b+c+d+... The range of a+b+c+d+... is 0 to 250μm. The diameter of the support plate 20 is Φ, Φ≥A'.

[0072] In this embodiment, the annular step 210 closest to the outer edge of the support plate 20 among the annular steps 210 is an edge step 211 , and the outer edge of the side of the edge step 211 facing away from the base plate 10 is arc-shaped.

[0073] In the above implementation, the edge step 211 corresponds to the outer edge of the substrate, that is, the edge step 211 directly supports the outer edge of the substrate. The outer edge of the substrate is the part where the substrate is most warped, so the outer edge of the side of the edge step 211 facing away from the base plate 10 is designed to be arc-shaped, so that the edge step 211 can better support the outer edge of the substrate, so as to avoid an excessive gap between the substrate and the edge step 211.

[0074] In this embodiment, the annular step 210 closest to the outer edge of the support plate 20 among the annular steps 210 is a central step 212 , and the area surrounded by the central step 212 is a plane.

[0075] In the above implementation, the central step 212 corresponds to the middle of the substrate, that is, the central step 212 directly supports the middle of the substrate. The middle of the substrate is the part with the smallest warping degree of the substrate, so the area surrounded by the central step 212 is designed as a plane, which can better support the middle of the substrate and avoid an excessive gap between the substrate and the support plate 20.

[0076] Figure 3 A schematic diagram of a graphite tray provided in an embodiment of the present disclosure, combined with Figure 3 In this embodiment, the graphite tray includes a main tray body 100, a cover 200 and Figures 1-2 A planetary disk 300 is shown.

[0077] The cover 200 is attached to one side of the main disk body 100 , and has a plurality of accommodating holes 2100 arranged at intervals from each other, and the accommodating holes 2100 correspond to the planetary disks 300 one by one. The planetary disks 300 are located in the corresponding accommodating holes 2100 .

[0078] The main disk body 100 is used to provide an installation base for the cover 200 and the planetary disk 300. The cover 200 is arranged on one side of the main disk body 100, so that the hole wall of the accommodating hole 2100 and one side of the main disk body 100 together constitute a groove for accommodating the planetary disk 300. The planetary disk 300 is placed in the accommodating hole 2100 for carrying the substrate. The planetary disk includes a base disk 10 and a support disk 20, wherein the support disk 20 is used to support the substrate, and the base plate provides a foundation for the support disk 20 to ensure the stability of the support disk 20, which is conducive to the support disk 20 to stably support the substrate. The side of the support disk 20 facing away from the base disk 10 has a plurality of annular steps 210, that is, the side of the support disk 20 used to support the substrate has a plurality of annular steps 210. Since the annular steps 210 are arranged concentrically, and the height of each annular step 210 increases or decreases one by one in the radial direction of the support disk 20, the substrate support surface formed by each annular step 210 is generally convex in the middle or concave in the middle. In this way, the substrate support surface formed by each annular step 210 can match the edge warping generated by the substrate, thereby effectively reducing the gap between the edge of the substrate and the planetary disk, which is conducive to improving the heating uniformity of the substrate, and further ensuring the in-chip wavelength uniformity of the prepared epitaxial wafer.

[0079] That is to say, the planetary disk provided in the embodiment of the present disclosure, by arranging a plurality of annular steps 210 on the side of the support disk 20 facing away from the base disk 10, enables the substrate supporting surface formed by each annular step 210 to match the edge warping produced by the substrate, thereby effectively reducing the gap between the edge of the substrate and the planetary disk, which is beneficial to improving the heating uniformity of the substrate, and further ensuring the in-wafer wavelength uniformity of the prepared epitaxial wafer.

[0080] Exemplarily, the cover 200 is a graphite sheet-like structure, which can be attached to one side of the main plate body 100 and form the receiving hole 2100 on the main plate body 100 by using its own thickness.

[0081] In some examples, the cover 200 includes sub-cover sheets 2200 of various shapes, and the sub-cover sheets 2200 are arranged on the main plate body 100 according to the shape of the main plate body 100 and the arrangement of the receiving holes 2100. In other words, by adjusting the arrangement of the sub-cover sheets 2200 on the main plate body 100, the position, size, number, etc. of the receiving holes 2100 can be changed accordingly, so that the required receiving holes 2100 can be spliced ​​on the main plate body 100.

[0082] Exemplarily, the receiving holes 2100 are arranged at intervals along the circumferential direction of the outer edge of the main disk body 100 , and the distance between two adjacent receiving holes 2100 is the same, so as to ensure that the planetary disk 300 in each receiving hole 2100 can be heated evenly.

[0083] In some examples, a sub-cover sheet 2200 has a positioning bump 2300. The positioning bump 2300 can facilitate positioning of the graphite tray by other components of the metal organic chemical vapor deposition device, such as a robot arm, etc. The positioning bump 2300 can be flexibly applied according to needs, and the present disclosure does not limit this.

[0084] Figure 4 This is the AA cross-sectional view of the graphite tray, combined with Figure 4 In this embodiment, the main disk body 100 has an air flow channel 1100 , and the air outlet port of the air flow channel 1100 is located in the accommodating hole 2100 .

[0085] In the above implementation, the air inlet port of the air flow channel 1100 is connected to the air source, and the air flow is output through the air outlet port, which can lift the planetary disk 300 so that the planetary disk 300 is suspended on the main disk body 100 and rotates in the accommodating hole 2100 driven by the air flow.

[0086] Exemplarily, the extension direction of the airflow channel 1100 is parallel to the main disk body 100 to ensure that the gas flows smoothly in the airflow channel 1100 .

[0087] In addition to the planetary disk 300 rotating relative to the main disk body 100 under the drive of the gas, the main disk body 100 can also rotate itself under the drive of the motor. In this embodiment, the graphite tray is applied to a low-speed metal organic chemical vapor deposition device, and the speed of the main disk body 100 is about 8rpm.

[0088] Exemplarily, the size of the main disk body 100 is 4 inches to 12 inches, for example, 4 inches, 6 inches, 8 inches, 12 inches, etc.

[0089] In this embodiment, the graphite tray further includes a first mounting member 400 and a second mounting member 500. The first mounting member 400 is plugged into the cover member 200 and the main tray body 100 respectively, and the second mounting member 500 is plugged into the base tray 10 and the main tray body 100 respectively.

[0090] In the above implementation, the first mounting member 400 is used to mount the cover 200 on the main disk body 100, and the second mounting member 500 is used to mount the base 10 on the main disk body 100. Through the first mounting member 400 and the second mounting member 500, the cover 200 and the base 10 can be stably mounted on the main disk body 100.

[0091] Exemplarily, the first mounting member 400 and the second mounting member 500 are both latches, a first end of the latch is plugged into the cover 200 or the base plate 10 , and a second end of the latch is plugged into the main plate body 100 .

[0092] It is worth noting that the base plate 10 is rotatably connected to the second mounting member 500, and the rotation axis of the base plate 10 is coaxial with the axis of the second mounting member 500. In this way, in addition to being able to realize the installation of the base plate 10 on the main plate body 100, the second mounting member 500 can also serve as the rotation axis of the base plate 10, so that the planetary plate 300 can stably rotate relative to the main plate body 100.

[0093] Exemplarily, the second mounting member 500 is adjacent to the outlet port of the airflow channel 1100, that is, the rotation axis of the planetary disk 300 is adjacent to the outlet port of the airflow channel 1100. Such an arrangement facilitates the airflow output from the outlet port of the airflow channel 1100 to drive the planetary disk 300 to rotate.

[0094] Exemplarily, the first mounting member 400 is a quartz structural member, and the second mounting member 500 is a molybdenum alloy structural member.

[0095] Unless otherwise defined, the technical terms or scientific terms used herein shall have the usual meanings understood by persons of ordinary skill in the field to which the present disclosure belongs. The words "first", "second", "third" and similar words used in the patent application specification and claims of the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "one" do not indicate a quantity limitation, but indicate the existence of at least one. Words such as "include" or "comprise" and similar words mean that the elements or objects appearing before "include" or "comprise" include the elements or objects listed after "include" or "comprise" and their equivalents, and do not exclude other elements or objects. Words such as "connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0096] The above description is only an optional embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A planetary disk, characterized in that: Applied to a graphite tray, the planetary disk comprises a base disk (10) and a support disk (20); The base plate (10) is coaxially connected to the support plate (20), and the outer diameter of the base plate (10) is not less than the outer diameter of the support plate (20); The support plate (20) has a plurality of annular steps (210) on a side facing away from the base plate (10), and the annular steps (210) are arranged concentrically. In the radial direction of the support plate (20), the height of each annular step (210) increases or decreases one by one, and the height of the annular step (210) is the dimension of the annular step (210) in the axial direction of the support plate (20).

2. The planetary disk according to claim 1, characterized in that: In the radial direction of the support plate (20), the height of each of the annular steps (210) is an arithmetic progression; or, In the radial direction of the support plate (20), the height of each of the annular steps (210) is a geometric progression.

3. The planetary disk according to claim 1, characterized in that: The height of the annular step (210) is 150-250 nm.

4. The planetary disk according to claim 1, characterized in that: The sum of the heights of the annular steps (210) is 1.8 to 2.2 μm.

5. The planetary disk according to claim 1, characterized in that: In the radial direction of the support disk (20), the width of each annular step (210) increases or decreases one by one, and the height of the annular step (210) is the dimension of the annular step (210) in the radial direction of the support disk (20).

6. The planetary disk according to claim 5, characterized in that: In the radial direction of the support plate (20), the width of each of the annular steps (210) is an arithmetic progression; or, In the radial direction of the support plate (20), the width of each of the annular steps (210) is a geometric progression.

7. The planetary disk according to claim 5, characterized in that: The width of the annular step (210) is no greater than 250 μm.

8. The planetary disk according to claim 1, characterized in that: Among the annular steps (210), the annular step (210) closest to the outer edge of the support plate (20) is an edge step (211), and the outer edge of the edge step (211) facing away from the base plate (10) is arc-shaped.

9. The planetary disk according to claim 1, characterized in that: Among the annular steps (210), the annular step (210) closest to the outer edge of the support plate (20) is a central step (212), and the area surrounded by the central step (212) is a plane.

10. A graphite tray, characterized in that: It comprises a main disk body (100), a cover (200) and a plurality of planetary disks (300) according to any one of claims 1 to 9; The cover (200) is attached to one side of the main disk body (100), and the cover (200) has a plurality of accommodating holes (2100) arranged at intervals from each other, and the accommodating holes (2100) correspond one to one with the planetary disks (300); The planetary disk (300) is located in the corresponding receiving hole (2100).

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