Graphite plate

Abstract

The utility model relates to the technical field of semiconductor material growth, in particular to a graphite plate, which comprises a plate body, a plurality of groove rings are arranged on the plate body, the diameters of the groove rings are gradually increased from the center to the periphery, each groove ring comprises a plurality of grooves which are connected in series, a plurality of steps are arranged on the edge of each groove at intervals, a concave area is arranged in the middle of each groove, and a plurality of grooves are formed in the concave area. A plane area is arranged between the concave area and the step, the height of the concave area is lower than that of the plane area, and the height of the step is higher than that of the plane area. According to the utility model, the heating temperature uniformity in the epitaxial wafer can be improved, the wavelength uniformity in the epitaxial wafer is further improved, the wavelength uniformity between the epitaxial wafers is also improved, and the technical problem that the epitaxial wafer yield is reduced due to the fact that a graphite disc structure in the prior art is easy to cause large wavelength difference in the epitaxial wafer is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of semiconductor material growth, in particular to a graphite disk. Background Art

[0002] As a new type of efficient, environmentally friendly and green solid-state lighting source, LED has been widely used for indoor and outdoor lighting. It is also widely used in traffic lights, car lights and mobile phone / TV displays.

[0003] Currently, the main method for producing LED epitaxial wafers is through metal organic compound vapor deposition (MOCVD). The epitaxial wafer carrier in MOCVD is usually a graphite disk. The process can be briefly described as follows: the substrate is placed in the groove of the graphite disk, and the graphite disk carrying the substrate is placed in the MOCVD reaction chamber. By heating the reaction chamber to a preset temperature and introducing organic metal compounds and gases, they form LED epitaxial layers on the substrate.

[0004] Graphite disks are crucial components in metal organic vapor deposition (MOCVD) equipment. Currently, commonly used graphite disks are round and feature circular grooves for accommodating substrates. Graphite disks are made of high-purity graphite and coated with silicon carbide (SiC). During epitaxial growth, heating filaments radiate heat to the graphite disk containing the substrate within the MOCVD reaction chamber. The heating temperature is controlled by thermocouples and a temperature controller, typically achieving a temperature control accuracy of 0.2°C or less. Currently, sapphire (Al2O3) substrates are commonly used to grow LED epiwafers. Because epiwafer wavelengths are temperature-sensitive, this can lead to significant wavelength variations within the epiwafer, resulting in reduced epiwafer yield.

[0005] In summary, there is an urgent need for a graphite disk that can significantly improve the wavelength uniformity within an epitaxial wafer to solve the problems existing in the prior art. Utility Model Content

[0006] The purpose of the utility model is to provide a graphite disk to solve the technical problem that the graphite disk structure in the prior art easily causes large wavelength differences within the epitaxial wafer, resulting in a decrease in the yield of the epitaxial wafer. The specific technical solution is as follows:

[0007] The utility model provides a graphite disk, comprising a disk body, wherein a plurality of groove rings are provided on the disk body, the diameters of which gradually increase from the center to the periphery, each of the groove rings comprises a plurality of grooves connected in series, a plane area is provided at the edge of the groove, a plurality of steps are provided at intervals on the plane area, a plane area is provided between the concave area and the steps, the height of the concave area is lower than the height of the plane area, and the height of the steps is higher than the height of the plane area.

[0008] A further improvement of the graphite disk of the present invention is that an inclined section is provided at the lower portion of the side wall of the groove, and the diameter of the upper end of the inclined section is smaller than the diameter of the lower end of the inclined section.

[0009] A further improvement of the graphite disk of the present invention is that a vertical section is provided in the middle of the side wall of the groove, and the lower end of the vertical section is connected to the upper end of the inclined section.

[0010] A further improvement of the graphite disk of the present invention is that an arc section is provided on the upper portion of the side wall of the groove, the lower end of the arc section is connected to the upper end of the vertical section, and the upper end of the arc section is connected to the top surface of the disk body.

[0011] A further improvement of the graphite disc of the present invention is that the number of the steps is six, and the six steps are arranged at intervals along the circumferential direction of the side wall of the groove.

[0012] A further improvement of the graphite disk of the present invention is that the height difference between the concave area and the flat area is between 0.015 and 0.025 mm.

[0013] A further improvement of the graphite disk of the present invention is that the height difference between the step and the plane area is between 0.05 and 0.15 mm.

[0014] A further improvement of the graphite disc of the present invention is that the number of the groove rings is three, and the three groove rings are arranged adjacent to each other inside and outside.

[0015] The application of the technical solution of the utility model has the following beneficial effects:

[0016] The graphite disk of the present invention places the epitaxial wafer on a step. Due to a certain height difference between the concave area and the step, the epitaxial wafer is in an overhead state. There is a space for air flow between the concave area and the epitaxial wafer, so that the temperature of the center of the epitaxial wafer is taken away by the gas, thereby reducing the temperature difference between the center and the edge of the epitaxial wafer, improving the heating temperature uniformity within the epitaxial wafer, and further improving the wavelength uniformity within the epitaxial wafer. The wavelength uniformity between the epitaxial wafers is also improved, which solves the technical problem in the prior art that the graphite disk structure easily causes large wavelength differences within the epitaxial wafer, resulting in a decrease in the yield of the epitaxial wafer.

[0017] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0019] Figure 1 It is a top view of the graphite disc of the utility model;

[0020] Figure 2 It is a top view of the groove of the graphite disk of the utility model;

[0021] Figure 3 yes Figure 2 Cross-sectional view on the AA line side;

[0022] Among them, 1. disk body; 2. groove; 3. step; 4. flat area; 5. concave area; 6. inclined section; 7. vertical section; 8. arc section. DETAILED DESCRIPTION

[0023] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0024] The temperature of gases such as N2 and NH3 in the flow field system within the metal organic compound vapor deposition (MOCVD) chamber is maintained at 50°C, while the graphite disk is continuously heated by a heating filament at a temperature of approximately 1,000°C. Therefore, the gas blowing over the graphite disk is like cold air. Because the heat transfer coefficient of sapphire is lower than that of graphite, the temperature of the epitaxial wafer periphery is likely to be lower than that of the center. In addition, when growing 2D and nGaN (gallium nitride) epitaxial wafers, the bowl-shaped warping of the epitaxial wafer will cause the periphery of the epitaxial wafer to move away from the graphite disk, resulting in the heating temperature of the epitaxial wafer periphery being lower than that of the center, thereby affecting the wavelength uniformity between epitaxial wafers.

[0025] See also Figures 1 to 3 As shown, a graphite disk includes a disk body 1, which is provided with a plurality of groove rings with gradually increasing diameters from the center to the periphery. Each groove ring includes a plurality of grooves 2 connected in series. The edges of the grooves 2 are provided with a flat area 4, and the flat area 4 is provided with a plurality of steps 3 at intervals. The middle of the groove 2 is provided with a concave area 5, the height of the concave area 5 is lower than the height of the flat area 4, and the height of the steps 3 is higher than the height of the flat area 4.

[0026] In this embodiment, the graphite disk and the groove 2 are both circular, the diameter of the graphite disk is in the range of 715.6 to 716.4 mm, the thickness is in the range of 15.9 to 16.1 mm, the diameter of a single groove 2 is in the range of 100.78 to 100.82 mm, and the groove depth is in the range of 0.785 to 0.795 mm.

[0027] The graphite disk of the present invention can improve the heating temperature uniformity of the epitaxial wafer. The epitaxial wafer is placed on the step 3. By providing a concave area 5 (concave) of a reasonable depth in the middle area of ​​a single groove 2, the heating temperature uniformity within the epitaxial wafer can be further improved, which is beneficial to improving the uniformity of the In (indium) component in InGaN (gallium nitride). Because InN (indium nitride) is easily decomposed and greatly affected by temperature, the In component in InGaN directly determines the wavelength of the epitaxial wafer. The graphite disk of the present invention improves the heating temperature uniformity within the epitaxial wafer, thereby improving the wavelength uniformity within the epitaxial wafer, and also improving the wavelength uniformity between epitaxial wafers.

[0028] Preferably, the lower portion of the sidewall of the groove 2 is provided with an inclined section 6, the upper diameter of which is smaller than the lower diameter of the inclined section 6. In this embodiment, the angle between the inclined section 6 and the vertical section 7 is 10°. Since the epitaxial wafer is grown at high speed, the upper end of the inclined section 6 of the sidewall is inclined toward the center of the groove 2, which can block the epitaxial wafer and prevent it from flying or being thrown off.

[0029] Preferably, a vertical section 7 is provided in the middle of the sidewall of the groove 2, and the lower end of the vertical section 7 is connected to the upper end of the inclined section 6. In this embodiment, the height of the vertical section 7 is 0.1 mm. The vertical section 7 provides a certain support for the substrate.

[0030] Preferably, an arcuate segment 8 is provided on the upper portion of the sidewall of the groove 2. The lower end of the arcuate segment 8 is connected to the upper end of the vertical segment 7, and the upper end of the arcuate segment 8 is connected to the top surface of the disk body 1. In this embodiment, the radius of the arcuate segment 8 is 0.25 mm. The arcuate segment 8 facilitates placement of epitaxial wafers. When placing an epitaxial wafer, a pointed suction pen is used to hold the bottom of the substrate, then inserted diagonally into the opposite sidewall of the groove 2. The suction pen is then released, and the substrate can slide smoothly along the arcuate segment 8 into the groove 2.

[0031] Preferably, the number of the steps 3 is six, and the six steps 3 are arranged at intervals along the circumferential direction of the side wall of the groove 2, so that the epitaxial wafer can be placed stably.

[0032] Preferably, the height difference between the concave region 5 and the flat region 4 is between 0.015 and 0.025 mm. The diameter of the concave region 5 is between 95.98 and 96.02 mm, and the width of the flat region 4 between the step 3 and the concave region 5 is 2 mm. The concave region 5 provides space for gas flow below the epitaxial wafer, thereby lowering the center temperature of the epitaxial wafer, preventing it from being too high, and ensuring that the temperature inside the epitaxial wafer is more closely aligned with the surface temperature of the graphite disk.

[0033] Preferably, the height difference between the step 3 and the flat area 4 is between 0.05 and 0.15 mm. The step 3 is used for placing the epitaxial wafer and also provides space for the epitaxial wafer to bend downward during high-temperature growth.

[0034] Preferably, there are three groove rings, which are arranged adjacent to each other. In this embodiment, there are a total of 36 grooves 2 on the disc body 1, divided into three circles: inner, middle and outer. The centerline diameter of the outermost circle grooves 2 is within the range of 592.6 to 593.4 mm, the centerline diameter of the middle circle grooves 2 is within the range of 393.4 to 394 mm, and the centerline diameter of the inner circle grooves 2 is within the range of 203.6 to 204 mm.

[0035] The graphite disk of the present invention places the epitaxial wafer on the step 3. Since there is a certain height difference between the concave area 5 and the step 3, there is a space for air flow between the concave area 5 and the epitaxial wafer, so that the temperature of the center of the epitaxial wafer is taken away by the gas, thereby reducing the temperature difference between the center and the edge of the epitaxial wafer, improving the heating temperature uniformity within the epitaxial wafer, and further improving the wavelength uniformity within the epitaxial wafer. The wavelength uniformity between the epitaxial wafers is also improved, which solves the technical problem in the prior art that the graphite disk structure easily causes large wavelength differences within the epitaxial wafer, resulting in a decrease in the yield of the epitaxial wafer.

[0036] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A graphite disk, characterized in that: The invention comprises a disk body (1), wherein the disk body (1) is provided with a plurality of groove rings whose diameters gradually increase from the center to the periphery, each of the groove rings comprises a plurality of grooves (2) connected in series, a plane area (4) is provided at the edge of the groove (2), a plurality of steps (3) are provided at intervals on the plane area (4), a concave area (5) is provided in the middle of the groove (2), the height of the concave area (5) is lower than the height of the plane area (4), and the height of the steps (3) is higher than the height of the plane area (4).

2. The graphite disk according to claim 1, characterized in that An inclined section (6) is provided at the lower portion of the side wall of the groove (2), and the diameter of the upper end of the inclined section (6) is smaller than the diameter of the lower end of the inclined section (6).

3. The graphite disk according to claim 2, characterized in that A vertical section (7) is provided in the middle of the side wall of the groove (2), and the lower end of the vertical section (7) is connected to the upper end of the inclined section (6).

4. The graphite disk according to claim 3, characterized in that An arc segment (8) is provided on the upper portion of the side wall of the groove (2), the lower end of the arc segment (8) is connected to the upper end of the vertical segment (7), and the upper end of the arc segment (8) is connected to the top surface of the disk body (1).

5. The graphite disk according to claim 1, characterized in that The number of the steps (3) is six, and the six steps (3) are arranged at intervals along the circumferential direction of the side wall of the groove (2).

6. The graphite disk according to claim 1, characterized in that The height difference between the concave area (5) and the flat area (4) is between 0.015 and 0.025 mm.

7. The graphite disk according to claim 1, characterized in that The height difference between the step (3) and the plane area (4) is between 0.05 and 0.15 mm.

8. The graphite disk according to claim 1, characterized in that There are three groove rings, and the three groove rings are arranged adjacent to each other inside and outside.

Images