Heating device and CVD equipment

Abstract

The utility model relates to the technical field of chemical vapor deposition preparation, in particular to a heating device and CVD equipment. The heating device comprises a coil assembly, a graphite disc and a heat conducting gasket, the coil assembly comprises a coil and a power supply device, the coil is arranged on the circumferential outer surface of a cavity of the CVD equipment, and the power supply device is used for supplying power to the coil so that a magnetic field can be generated in the cavity; the graphite disc is used for being installed in the cavity and can generate heat; the heat-conducting gasket is located on the graphite plate and is coaxial with the graphite plate, and the diameter of the heat-conducting gasket is smaller than that of the graphite plate; the heat-conducting gasket is used for supporting a wafer, the diameter of the wafer is larger than that of the heat-conducting gasket, the wafer comprises a first area and a second area, the first area can be in direct contact with the heat-conducting gasket, and a gap is formed between the second area and the graphite disc. Through the heating mode of combining heat conduction and heat radiation, the uniformity of wafer temperature distribution is improved, and the uniformity and quality of the two-dimensional material film are improved.

Description

Technical Field

[0001] This disclosure relates to the field of chemical vapor deposition (CVD) preparation technology, and in particular to a heating device for CVD equipment. Background Technology

[0002] When fabricating two-dimensional materials (such as graphene, molybdenum disulfide, MXene, etc.) thin films using a cold-wall chemical vapor deposition (CVD) apparatus, the uniformity of the wafer temperature distribution directly affects the thickness uniformity and quality of the film. Due to the skin effect of electromagnetic induction, when a high-frequency electric field or electromagnetic wave passes through a conductor, the energy is mainly concentrated near the conductor surface. Therefore, the skin effect results in a highly uneven temperature distribution on the graphite disk and wafer surface, with higher temperatures near the edges and lower temperatures near the center, thus affecting the thickness uniformity and quality of the film. Utility Model Content

[0003] The purpose of this disclosure is to provide a heating device and CVD equipment to improve the thickness uniformity and quality of two-dimensional material films.

[0004] To achieve the above objectives, this disclosure provides a heating device applied to the chamber of a CVD equipment, the heating device comprising:

[0005] A coil assembly, comprising a coil and a power supply device, wherein the coil is disposed on the circumferential outer surface of the chamber, and the power supply device is used to supply power to the coil to generate a magnetic field within the chamber;

[0006] A graphite disk, which is installed within the cavity, is capable of generating heat under the influence of a magnetic field; and

[0007] A thermally conductive pad is located on the graphite disk and is coaxially arranged with the graphite disk. The diameter of the thermally conductive pad is smaller than the diameter of the graphite disk. The thermally conductive pad is used to support a wafer, wherein the diameter of the wafer is larger than the diameter of the thermally conductive pad. The wafer includes a first region and a second region. The first region can directly contact the thermally conductive pad, and the second region is separated from the graphite disk by a gap.

[0008] In one embodiment of this disclosure, the radius of the thermal pad is 0.3 to 0.9 times the radius of the graphite disk.

[0009] In one embodiment of this disclosure, the radius of the thermal pad is 0.35 to 0.8 times the radius of the wafer.

[0010] In one embodiment of this disclosure, the thickness of the thermal pad is 0.5 to 1 mm.

[0011] In one embodiment of this disclosure, the axial dimension of the coil is larger than the axial dimension of the graphite disk.

[0012] In one embodiment of this disclosure, the center of the coil and the center of the graphite disk are in the same plane, wherein the center of the coil is a point on the axis of the coil, the distance from this point to both ends of the coil is equal, and the plane is perpendicular to the axis of the graphite disk.

[0013] In one embodiment of this disclosure, the coils are spirally wound around the circumferential outer surface of the chamber, and the coils have equal pitch.

[0014] In one embodiment of this disclosure, the thermal pad is made of graphite.

[0015] In one embodiment of this disclosure, the heating device further includes a support platform installed below the graphite disk for supporting the graphite disk.

[0016] For the purposes described above, this disclosure also provides a CVD apparatus, including a chamber and the heating device, wherein the coil is disposed on the circumferential outer surface of the chamber and the graphite disk is installed inside the chamber.

[0017] The main beneficial effects of this disclosure are:

[0018] The heating device disclosed herein is installed in the chamber of a CVD equipment during use. The wafer is placed on a thermal pad, with a first region of the wafer in direct contact with the thermal pad. When the power supply device supplies power to the coil, for example, by supplying a high-frequency alternating current to the coil, the graphite disk generates eddy currents due to electromagnetic induction, thereby generating heat. Due to the skin effect, the temperature near the edge of the graphite disk is higher, while the temperature near the center is lower; that is, the area of ​​the graphite disk corresponding to the thermal pad has a lower temperature. Since the first region of the wafer is in direct contact with the thermal pad, it can receive direct heat conduction from the thermal pad. Due to the gap between the second region of the wafer and the graphite disk, the second region receives heat radiation from the graphite disk. Since direct heat conduction is more efficient than heat radiation, the temperature of the first region of the wafer, corresponding to the lower temperature area of ​​the graphite disk, rises faster through direct heat conduction. At the same time, the temperature rise of the second region of the wafer, which originally corresponded to the higher temperature area of ​​the graphite disk, is moderated through heat radiation, resulting in more uniform heating of the entire wafer. The reaction gases in the chamber undergo a chemical reaction on a uniformly heated wafer, and the reaction products are deposited and grown relatively uniformly on the wafer to form a two-dimensional material thin film. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the specific embodiments of this disclosure or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 A schematic diagram of the structure of the heating device provided in the embodiments of this disclosure;

[0021] Figure 2 for Figure 1 A sectional view along line AA;

[0022] Figure 3 A schematic diagram of a wafer heated by a heating device provided in an embodiment of this disclosure;

[0023] Figure 4 Isotherm distribution diagram within the chamber of the CVD equipment provided in this embodiment of the disclosure;

[0024] Figure 5 Temperature field distribution diagram of a wafer heated by a CVD apparatus provided in an embodiment of this disclosure;

[0025] Figure 6 This is a schematic diagram of a visualization of the graphene wafer prepared in Example 1 of this disclosure;

[0026] Figure 7 The Raman spectrum of the graphene wafer prepared in Example 1 of this disclosure;

[0027] Figure 8 This is a schematic diagram of the surface resistivity characterization of the graphene wafer prepared in Example 1 of this disclosure;

[0028] Figure 9 An atomic force microscope image of the central region of the graphene wafer prepared in Example 1 of this disclosure;

[0029] Figure 10 An atomic force microscope image of the edge region of the graphene wafer prepared in Example 1 of this disclosure;

[0030] Figure 11 The isotherm distribution diagram inside the chamber of the ordinary CVD equipment in Comparative Example 1;

[0031] Figure 12 Temperature field distribution of the wafer heated by the conventional CVD equipment in Comparative Example 1;

[0032] Figure 13 These are temperature curves of the wafers at different radial positions in Example 1 and Comparative Example 1;

[0033] Figure 14 The Raman spectrum of the graphene wafer prepared in Comparative Example 1 is shown.

[0034] Figure 15 This is a schematic diagram of the surface resistivity characterization of the graphene wafer prepared in Comparative Example 1.

[0035] Figure 16 An atomic force microscope image of the central region of the graphene wafer prepared in Comparative Example 1;

[0036] Figure 17 An atomic force microscope image of the edge region of the graphene wafer prepared in Comparative Example 1.

[0037] The annotations in the attached figures are explained as follows:

[0038] 101-Cavity;

[0039] 102 - Coil;

[0040] 103-Graphite disk;

[0041] 104 - Thermal pad;

[0042] 105 - Wafer;

[0043] 1051 - First Region;

[0044] 1052 - Second Region;

[0045] 106 - Support platform. Detailed Implementation

[0046] The technical solutions of this disclosure will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this disclosure, not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0047] In the description of this disclosure, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., 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 disclosure 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 disclosure. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0048] In the description of this disclosure, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure based on the specific circumstances.

[0049] See Figures 1 to 17 As shown, this embodiment provides a heating device applied to the chamber 101 of a CVD equipment. The heating device includes a coil assembly, a graphite disk 103, and a thermally conductive pad 104. The coil assembly includes a coil 102 and a power supply device. The coil 102 is disposed on the circumferential outer surface of the chamber 101, and the power supply device supplies power to the coil 102 to generate a magnetic field within the chamber 101. The graphite disk 103 is installed inside the chamber 101 and can generate heat under the influence of the magnetic field. A thermal pad 104 is located on a graphite disk 103 and is coaxially arranged with the graphite disk 103. The diameter of the thermal pad 104 is smaller than the diameter of the graphite disk 103. The thermal pad 104 is used to support a wafer 105, wherein the diameter of the wafer 105 is larger than the diameter of the thermal pad 104. The wafer 105 includes a first region 1051 and a second region 1052. The first region 1051 can directly contact the thermal pad 104, and the second region 1052 is spaced apart from the graphite disk 103.

[0050] In this embodiment, the heating device is installed in the chamber 101 of the CVD equipment, and the wafer is placed on the thermal pad 104, with the first region 1051 of the wafer in direct contact with the thermal pad 104. When the power supply device supplies power to the coil 102, for example, when the power supply device supplies high-frequency alternating current to the coil 102, the graphite disk 103 generates eddy currents due to electromagnetic induction, thereby generating heat. Due to the skin effect, the temperature of the area of ​​the graphite disk 103 near the edge is higher, while the temperature of the area near the center is lower; that is, the temperature of the area of ​​the graphite disk 103 corresponding to the thermal pad 104 is lower. Since the first region 1051 of the wafer is in direct contact with the thermal pad 104, it can receive direct heat conduction from the thermal pad 104. Because the second region 1052 of the wafer has a gap with the graphite disk 103, it receives heat radiation from the graphite disk 103. Since direct heat conduction is more efficient than heat radiation, the temperature of the first region 1051 of the wafer, corresponding to the lower temperature area of ​​the graphite disk 103, rises faster through direct heat conduction. Simultaneously, heat radiation moderates the temperature rise of the second region 1052 of the wafer, which originally corresponded to the higher temperature area of ​​the graphite disk 103, resulting in more uniform heating of the entire wafer. The reaction gas inside the chamber 101 undergoes a chemical reaction on the uniformly heated wafer, and the reaction products are deposited and grown relatively uniformly on the wafer to form a two-dimensional material thin film, such as a graphene film, a molybdenum disulfide film, or an MXene film.

[0051] Therefore, the heating device provided in this embodiment improves the uniformity of wafer temperature distribution by combining heat conduction and heat radiation, which in turn helps to improve the uniformity and quality of two-dimensional material thin films.

[0052] Computer simulations revealed that the skin depth was approximately 5 mm within the experimental temperature range.

[0053] When placing wafer 105, the axis of wafer 105 should coincide with the axis of thermal pad 104 as much as possible to ensure uniform heating of the wafer.

[0054] When the axis of wafer 105 coincides with the axis of thermal pad 104, see [reference needed]. Figure 3 As shown, the area within the dashed line is the first region 1051 of wafer 105, which is circular in shape. The area between the dashed and solid lines is the second region 1052 of wafer 105, which is annular in shape. Along the radial direction of wafer 105, the first region 1051 is located within the second region 1052, and the first region 1051 and the second region 1052 are coaxially arranged.

[0055] In one embodiment, the radius of the thermal pad 104 is 0.3 to 0.9 times the radius of the graphite disk 103. With the thermal pad 104 coaxially positioned with the graphite disk 103, the thermal pad 104 can cover as much as possible the internal region of the graphite disk 103 where the temperature is lower due to the skin effect. In this internal region, heat from the graphite disk 103 is conducted to the first region 1051 of the wafer through the thermal pad 104. However, the region on the outer periphery of this internal region has a higher temperature due to the skin effect, and this region lacks the thermal pad 104, allowing the graphite disk 103 to heat the second region 1052 of the wafer through thermal radiation.

[0056] In one embodiment, the radius of the thermal pad 104 is 0.35 to 0.8 times the radius of the wafer 105. By selecting different radii of the thermal pad 104, direct heat conduction heating can be performed on first regions of different sizes.

[0057] For example, when the radius of the wafer is R, the area of ​​the first region 1051 is π×(0.35R). 2 ~π×(0.8R) 2 .

[0058] In one embodiment, the thickness of the thermal pad 104 is 0.5–1 mm. This helps to further enhance the heat conduction effect, while also preventing the distance between the wafer and the graphite disk 103 from becoming too large, thus ensuring the effect of heat radiation and further reducing the temperature difference between the first region 1051 and the second region 1052 of the wafer, thereby enhancing the uniformity of the wafer temperature distribution.

[0059] It should be understood that for the same CVD equipment, the radius of the graphite disk 103 is usually fixed. Therefore, a first radius range for the thermal pad 104 can be calculated. Simultaneously, a second radius range for the thermal pad 104 can be derived based on the radius of the wafer to be processed. In actual calculations, the first and second radius ranges can be combined to select a more suitable radius range for the thermal pad 104. Furthermore, the radius range of the wafer to be processed can be selected to ensure that the radius of the wafer, the radius of the thermal pad 104, and the radius of the graphite disk 103 are matched, thereby facilitating the production of higher-quality films.

[0060] In one embodiment, the axial dimension of the coil 102 is larger than the axial dimension of the graphite disk 103. This ensures that the entire graphite disk 103 is within the magnetic field, guaranteeing that the graphite disk 103 is heated as a whole and generates higher heat to increase the reaction temperature.

[0061] In one embodiment, the center of coil 102 and the center of graphite disk 103 are in the same plane, wherein the center of coil 102 is a point on the axis of coil 102, the distance from the point to the two ends of coil 102 is equal, and the plane is perpendicular to the axis of graphite disk 103.

[0062] In this embodiment, the graphite disk 103 is a cylindrical structure with uniform mass, and the center of the graphite disk 103 is the geometric center, which coincides with the center of gravity of the graphite disk 103.

[0063] Since the center of coil 102 and the center of graphite disk 103 are in the same plane, the heat of graphite disk 103 can be made uniform, which is conducive to enhancing the effect of heat conduction and heat radiation, and further improving the uniformity of wafer temperature distribution.

[0064] In one embodiment, the coil 102 is spirally wound around the circumferential outer surface of the chamber 101, and the pitch of the coil 102 is equal. This makes the magnetic field strength more uniform, which further helps to improve the uniformity of heating.

[0065] For example, in this embodiment, the coil 102 has four turns, and the distance between adjacent turns is equal.

[0066] In one embodiment, the thermal pad 104 is made of graphite.

[0067] It should be noted that the thermal pad 104 can also be made of other thermally conductive and insulating materials.

[0068] In one embodiment, see Figure 2 As shown, the heating device also includes a support platform 106, which is installed below the graphite disk 103 to support the graphite disk 103.

[0069] In some embodiments, the support platform 106 can be lifted and installed below the graphite disk 103. By adjusting the position of the support platform 106, the wafer 105 can be placed on the thermal pad 104, and the wafer with a two-dimensional material film grown on it can also be removed.

[0070] For example, the support stage 106 can be a crucible stage.

[0071] This embodiment also provides a CVD device, including a chamber 101 and a heating device provided in this embodiment. A coil 102 is disposed on the circumferential outer surface of the chamber 101, and a graphite disk 103 is installed inside the chamber 101.

[0072] The CVD equipment provided in this embodiment uses the heating device provided in this embodiment, which improves the uniformity of wafer temperature distribution through a combination of heat conduction and heat radiation, thereby improving the uniformity and quality of two-dimensional material thin films.

[0073] In use, the wafer is placed on the thermal pad 104 inside the chamber 101, with the first region 1051 of the wafer in direct contact with the thermal pad 104. When the power supply device supplies power to the coil 102, for example, when the power supply device supplies a high-frequency alternating current to the coil 102, the graphite disk 103 generates eddy currents due to electromagnetic induction, thereby generating heat. Due to the skin effect, the temperature of the area of ​​the graphite disk 103 near the edge is higher, while the temperature of the area near the center is lower; that is, the temperature of the area of ​​the graphite disk 103 corresponding to the thermal pad 104 is lower. Since the first region 1051 of the wafer is in direct contact with the thermal pad 104, it can receive direct heat conduction from the thermal pad 104. Because the second region 1052 of the wafer has a gap with the graphite disk 103, it receives heat radiation from the graphite disk 103. Since direct heat conduction is more efficient than heat radiation, the temperature of the first region 1051 of the wafer, corresponding to the lower temperature area of ​​the graphite disk 103, rises faster through direct heat conduction. Simultaneously, heat radiation moderates the temperature rise of the second region 1052 of the wafer, which originally corresponded to the higher temperature area of ​​the graphite disk 103, resulting in more uniform heating of the entire wafer. The reaction gas inside the chamber 101 undergoes a chemical reaction on the uniformly heated wafer, and the reaction products are deposited and grown relatively uniformly on the wafer to form a two-dimensional material film.

[0074] In one embodiment, the chamber 101 is formed by the inner cavity of a quartz tube. Exemplarily, the quartz tube has a circular cross-sectional shape and is coaxially arranged with the graphite disk 103.

[0075] When the coil 102 is energized, it is equivalent to an energized solenoid. According to the magnetic effect of the current, a magnetic field is generated in the inner cavity of the quartz tube. According to the magnetocaloric effect, the graphite disk 103 can generate heat under the action of the magnetic field.

[0076] The following is a detailed description of specific implementation methods.

[0077] Example 1

[0078] Using the CVD equipment provided in this embodiment, a graphene film is grown on a sapphire wafer with a diameter of 150 mm to form a graphene wafer. Through finite element simulation and experiments, the graphite disk 103 is selected with a height of 10 mm and a diameter of 155 mm. The thermal pad 104 has a thickness of 0.5 mm and a diameter of 110 mm.

[0079] See Figure 4 and Figure 5As shown, the CVD equipment provided in this embodiment has better temperature field uniformity during operation, and the wafer is heated more evenly as a whole, without the phenomenon that the temperature of the center part of the wafer is significantly lower than that of the outer part.

[0080] The uniformity of the prepared graphene wafers can typically be evaluated using three methods: visual inspection or optical microscopy, Raman spectroscopy, and sheet resistivity measurement. Visual images, Raman spectra, and sheet resistivity results of the prepared graphene wafers are shown below. Figures 6 to 8 As shown. Figure 6 As can be seen from the image, the prepared graphene wafer exhibits uniformity. Raman characterization was performed on it, with tests conducted at different locations (I, II, III, IV, and V) to characterize the overall uniformity. The Raman spectral characterization results are shown below. Figure 7 As shown. Figure 7 As can be seen, the defect peaks at positions I to V are extremely small, indicating that the graphene wafer has high crystallinity and extremely low defect density, which in turn indicates that the prepared graphene has high quality.

[0081] The sheet resistance of the prepared graphene wafer was characterized using a probe testing system (e.g., a four-probe electrical testing system) to illustrate the conductivity and uniformity of the graphene. The test results are as follows: Figure 8 As shown. Statistical analysis of the test data revealed that the average sheet resistivity of the graphene wafer prepared in this embodiment was 1400 Ω / sq, and the sheet resistivity deviation at all locations was within ±25%, demonstrating its good uniformity. For example, from... Figure 8 It can be seen that the resistance of the surface resistor at about 100 locations is 1250Ω / sq, which is close to the average value, while the resistance at only a few locations differs significantly from the average value. For example, there are only about 10 locations with a resistance of 2250Ω / sq.

[0082] It should be understood that for the direct preparation of graphene on c-plane sapphire wafers, when the CVD growth temperature reaches 1300℃, steps will appear on the wafer surface. These steps are very sensitive to temperature, and the temperature uniformity can be reflected by the morphology and width of the steps at different locations on the surface.

[0083] from Figure 9 and Figure 10 It can be seen that the graphene wafers prepared in this embodiment have more uniform steps in the center and edge portions, and are of better quality.

[0084] In summary, the graphene wafer sample obtained in Example 1 exhibits high uniformity.

[0085] Comparative Example 1

[0086] A graphene film was grown on a 150mm diameter sapphire wafer using conventional CVD equipment. The graphite disk in this conventional CVD equipment had a height of 10mm and a diameter of 155mm. The sapphire wafer was placed directly on the graphite disk.

[0087] See Figure 11 and Figure 12 As shown, conventional CVD equipment has poor temperature field uniformity during operation, resulting in uneven heating of the wafer as a whole. This leads to a noticeable phenomenon where the temperature in the center of the wafer is significantly lower than that in the outer periphery.

[0088] contrast Figure 4 and Figure 5 The temperature field uniformity and wafer heating uniformity in Example 1 are significantly higher than those in Comparative Example 1.

[0089] Further, see Figure 13 As shown, the gray upward-opening curve 1 represents the temperature of the wafer of Comparative Example 1 at different positions radially outward from the center, and the black downward-opening curve 2 represents the temperature of the wafer of Example 1 at different positions radially outward from the center.

[0090] First, let's look at curve 1. Due to the skin effect, the temperature is higher near the edge of the graphite disk and lower near the center. Therefore, when the wafer in Comparative Example 1 is placed directly on the graphite disk, the temperature of the wafer in the center of the graphite disk is significantly lower than that of the wafer near the edge of the graphite disk through heat conduction. As a result, the wafer in Comparative Example 1 is heated very unevenly.

[0091] Looking at curve 2, in Example 1, the first region 1051 of the wafer is in direct contact with the thermal pad 104, allowing it to receive direct heat conduction from the pad. Due to the gap between the second region 1052 of the wafer and the graphite disk 103, the second region 1052 receives heat radiation from the disk. Since direct heat conduction is more efficient than heat radiation, the temperature of the first region 1051 of the wafer, corresponding to the region with a lower temperature on the graphite disk 103, rises faster through direct heat conduction. For example, within a circular region with a radius of 40 mm, the temperature of the wafer in Example 1 is higher than that of the wafer in Comparative Example 1. Simultaneously, through heat radiation, the temperature rise of the second region 1052 of the wafer, which originally corresponded to the region with a higher temperature on the graphite disk 103, is moderated. For example, within an annular region with a radius greater than 55 mm, the temperature of the wafer in Example 1 is significantly lower than that of the wafer in Comparative Example 1, and closer to the temperature of its circular region, resulting in more uniform heating of the entire wafer.

[0092] It should be understood that in Embodiment 1, since the contact point between the wafer and the edge of the thermal pad 104 is also located in the region near the edge of the graphite disk 103, the circumferential portion with a radius of 55 mm on the wafer in Embodiment 1 may be simultaneously affected by heat conduction and the skin effect. Therefore, the temperature of this circumference may be the highest in the entire wafer. Nevertheless, it will not affect the overall heating uniformity of the wafer.

[0093] See Figure 14 As shown, the defect peaks at positions I to V are relatively high, indicating that the graphene wafer in Comparative Example 1 has poor crystal quality and a high defect density due to uneven heating.

[0094] The sheet resistivity of the graphene wafer in Comparative Example 1 was tested using the same test method as in Example 1, and the test results are as follows: Figure 15 As shown. Statistical analysis of the test data revealed that the average sheet resistivity of the graphene wafer prepared in Comparative Example 1 was 1400 Ω / sq, but the sheet resistivity deviation at all locations was within ±40%, a relatively large deviation, indicating poor uniformity of the graphene film. This is especially true for... Figure 15 The red and black areas in the graph have a surface resistivity of 0, indicating that the temperature in these areas is too high, the resulting steps are too large, and graphene films cannot be grown.

[0095] See Figure 16 and Figure 17 As shown, the central part of the graphene wafer prepared in Comparative Example 1 has a smaller step, but the step at the edge is obviously too large, which is not conducive to the growth of graphene film.

[0096] It should be noted that the heating device provided in this embodiment is also suitable for heating large-size wafers (e.g., eight-inch and twelve-inch). In this case, the size of the graphite disk 103 and the radius and thickness of the thermal pad 104 can be adjusted accordingly. For large-size wafers, there is no need to modify the magnetic field distribution of the electromagnetic induction coil, resulting in a simple structure and high heating efficiency. Furthermore, the heating device provided in this embodiment is more suitable for use in large-size CVD reaction chambers, as it is easy to process and control.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this disclosure, and are not intended to limit them. Although this disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this disclosure.

Claims

1. A heating device, characterized in that, The heating device, used in the chamber of a CVD equipment, includes: A coil assembly, comprising a coil and a power supply device, wherein the coil is disposed on the circumferential outer surface of the chamber, and the power supply device is used to supply power to the coil to generate a magnetic field within the chamber; A graphite disk, which is installed within the cavity, is capable of generating heat under the influence of a magnetic field; and A thermally conductive pad is located on the graphite disk and is coaxially arranged with the graphite disk. The diameter of the thermally conductive pad is smaller than the diameter of the graphite disk. The thermally conductive pad is used to support a wafer, wherein the diameter of the wafer is larger than the diameter of the thermally conductive pad. The wafer includes a first region and a second region. The first region can directly contact the thermally conductive pad, and the second region is separated from the graphite disk by a gap.

2. The heating device according to claim 1, characterized in that, The radius of the thermal pad is 0.3 to 0.9 times the radius of the graphite disk.

3. The heating device according to claim 1, characterized in that, The radius of the thermal pad is 0.35 to 0.8 times the radius of the wafer.

4. The heating device according to claim 1, characterized in that, The thickness of the thermal pad is 0.5 to 1 mm.

5. The heating device according to claim 1, characterized in that, The axial dimension of the coil is larger than the axial dimension of the graphite disk.

6. The heating device according to claim 1, characterized in that, The center of the coil and the center of the graphite disk are in the same plane, wherein the center of the coil is a point on the axis of the coil, and the distance from this point to the two ends of the coil is equal, and the plane is perpendicular to the axis of the graphite disk.

7. The heating device according to claim 1, characterized in that, The coils are spirally wound around the circumferential outer surface of the chamber, and the pitch of the coils is equal.

8. The heating device according to any one of claims 1 to 7, characterized in that, The thermal pad is made of graphite.

9. The heating device according to any one of claims 1 to 7, characterized in that, It also includes a support platform, which is installed below the graphite disk to support the graphite disk.

10. A CVD device, characterized in that, The device includes a chamber and a heating device according to any one of claims 1 to 9, wherein the coil is disposed on the circumferential outer surface of the chamber and the graphite disk is mounted inside the chamber.

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