Heating sheet, ceramic heating disc, method for manufacturing the same, and chemical vapor deposition apparatus

Abstract

The application relates to a heating sheet, a ceramic heating disc and a preparation method thereof and a chemical vapor deposition equipment. The heating sheet is divided into inner heating sheets and outer heating sheets and arranged in two layers, the ceramic heating disc is divided into two zones with high temperature and high uniformity, the heating sheet comprises the inner heating sheets and the outer heating sheets, the inner heating sheets and the outer heating sheets are independently connected with external power sources respectively, the inner heating sheets comprise inner heating coils, the outer heating sheets comprise outer heating coils, the temperature difference between the inner heating sheets and the outer heating sheets is reduced by adjusting the current ratio of the inner heating coils and the outer heating coils, and the outer circular area of the heating disc cannot cause the heat difference with the middle part due to heat dissipation, so that the heat unevenness of the heating disc is avoided.

Description

Technical Field

[0001] This application relates to the field of semiconductor manufacturing equipment technology, and in particular to a heating element, a ceramic heating plate, a method for preparing the same, and a chemical vapor deposition apparatus. Background Technology

[0002] In semiconductor chip manufacturing, silicon wafers undergo multiple thin film deposition and etching processes to complete chip fabrication. The chips then undergo testing, dicing, wire bonding, and packaging to form integrated circuit components. Chemical deposition (CVD) is a crucial step in semiconductor thin film fabrication. The primary function of the heating plate is to heat the wafer and maintain a uniform temperature across the entire wafer to achieve high-quality thin films. The quality of the thin film depends on its thickness, intra-wafer thickness uniformity, refractive index, stress, and grain size.

[0003] In the vacuum chamber of a CVD (Continuous Chemical Vapor Deposition) machine, a silicon wafer is placed directly above a heating plate. The heating plate contains embedded radio frequency (RF) electrodes and heating circuitry. The RF electrodes are only about 1 mm away from the silicon wafer above the heating plate. The RF electrodes can be grounded or biased to accelerate the movement of plasma onto the silicon wafer, thereby promoting thin film growth. The heating circuitry heats the silicon wafer to a high temperature to accelerate the reaction. The temperature uniformity of the silicon wafer determines the quality of the thin film and the yield rate of integrated circuit device production. Currently, aluminum nitride ceramics, which have good thermal conductivity, are mainly used to achieve more uniform heating temperatures. However, because heat is more easily lost from the outer periphery of the heating plate, it can easily cause uneven temperature distribution, with the inner area hotter than the outer area colder, affecting the use of the heating plate. Summary of the Invention

[0004] To address the aforementioned issues, this application provides a heating element, a ceramic heating plate, a method for preparing the same, and a chemical vapor deposition apparatus.

[0005] The present invention provides a heating element comprising an inner heating element and an outer heating element, wherein the inner heating element and the outer heating element are independently connected to an external power source. The inner heating element comprises an inner heating coil, and the outer heating element comprises an outer heating coil. The temperature difference between the inner heating element and the outer heating element is reduced by adjusting the current ratio of the inner heating coil and the outer heating coil.

[0006] The present invention provides a heating element comprising an inner heating element and an outer heating element, wherein the inner heating element and the outer heating element are independently connected to an external power source, the inner heating element comprising an inner heating coil, and the outer heating element comprising an outer heating coil, wherein the current ratio between the inner heating coil and the outer heating coil corresponds to the temperature difference between the areas heated by the inner heating element and the outer heating element.

[0007] One embodiment of this application provides a heating element, comprising: an inner heating element including multiple layers of inner heating coils arranged sequentially from the inside out and connected together, wherein the two ends of the first layer of inner heating coils are respectively connected to a first positive electrode and a first negative electrode; and an outer heating element including a first outer heating coil and a connecting coil, wherein the first outer heating coil is located outside the inner heating element, the connecting coil is located below the inner heating element, the first outer heating coil is connected to the connecting coil, and the two ends of the connecting coil are respectively connected to a second positive electrode and a second negative electrode.

[0008] According to some embodiments of this application, the heating coil in the first layer has a wire diameter of 0.5-2.5 mm and a wiring diameter of 1-60 mm; the heating wire of the heating coil in the second layer extends in a serpentine shape, with a wire diameter of 1-3 mm and a wiring diameter of 40-100 mm, wherein the distance between the inner endpoints of adjacent radial heating wires is 1-6 mm; the heating wire of the heating coil in the third layer extends in a serpentine shape, with a wire diameter of 2-4 mm and a wiring diameter of 80-110 mm, wherein the distance between the inner endpoints of adjacent radial heating wires is 2-7 mm; the heating wire of the heating coil in the fourth layer extends in a serpentine shape, with a wire diameter of 2-4 mm and a wiring diameter of 130-190 mm, wherein... The spacing between the inner ends of adjacent radial heating wires is 4-6 mm; the heating wire of the fifth inner heating coil extends in a serpentine shape, with a wire diameter of 2-4 mm and a wiring diameter of 170-240 mm, wherein the spacing between the inner ends of adjacent radial heating wires is 7-10 mm; the heating wire of the sixth inner heating coil extends in a serpentine shape, with a wire diameter of 2-4 mm and a wiring diameter of 220-270 mm, wherein the spacing between the inner ends of adjacent radial heating wires is 4-6 mm; the heating wire of the first outer heating coil extends in a serpentine shape, with a wire diameter of 2-4 mm and a wiring diameter of 250-320 mm, wherein the spacing between the inner ends of adjacent radial heating wires is 2-5 mm.

[0009] According to some embodiments of this application, the external heating element further includes a second external heating coil, which is disposed below the first external heating coil and located outside the connecting coil. The connecting coil is connected to the second external heating coil, and the second external heating coil is connected to the first external heating coil.

[0010] According to some embodiments of this application, the heating wire of the second external heating coil extends in a serpentine shape, with a wire diameter of 2-4 mm and a wiring diameter of 220-330 mm, wherein the distance between the inner ends of adjacent radial heating wires is 2-5 mm.

[0011] One embodiment of this application provides a ceramic heating plate, including a heating element as described above, wherein the heating element is disposed in the ceramic heating plate.

[0012] According to some embodiments of this application, the ceramic heating plate further includes: an electrode sheet disposed in the ceramic heating plate; a ceramic tube connected to the ceramic heating plate; and multiple electrode rods passing through the ceramic tube and respectively connected to the electrode sheet and the heating sheet.

[0013] According to some embodiments of this application, the ceramic heating plate is formed by hot pressing a pre-pressed first plate layer, a second plate layer, a third plate layer, and a fourth plate layer; the electrode sheet is disposed in the second plate layer; the inner heating sheet and the first outer heating coil of the heating plate are disposed in the third plate layer, and the connecting coil of the heating plate is disposed in the fourth plate layer.

[0014] According to some embodiments of this application, the second external heating coil of the heating element is disposed within the fourth disc layer.

[0015] According to some embodiments of this application, the ceramic heating plate is provided with a plurality of connection holes to expose the electrode sheet and the first positive electrode, the first negative electrode, the second positive electrode and the second negative electrode of the heating sheet respectively. One end of the plurality of electrode rods extends into the connection holes and connects to the first positive electrode, the first negative electrode, the second positive electrode and the second negative electrode of the electrode sheet and the heating component respectively.

[0016] One embodiment of this application provides a method for preparing a ceramic heating plate, comprising the steps of: pre-pressing ceramic raw material powder at room temperature to form a first plate layer; placing an electrode sheet on the first plate layer, filling it with ceramic raw material powder, and pre-pressing it at room temperature to form a second plate layer; placing an inner heating element and a first outer heating coil on the second plate layer, filling it with ceramic raw material powder, and pre-pressing it at room temperature to form a third plate layer, wherein the first outer heating coil is connected to a connecting electrode; placing a connecting coil on the third plate layer, connecting the connecting electrode to the connecting coil, filling it with ceramic raw material powder, and pre-pressing it at room temperature to form a fourth plate layer; hot-pressing the first plate layer, the second plate layer, the third plate layer, and the fourth plate layer to form a heating plate; sintering the heating plate and a ceramic tube together; and passing multiple electrode rods through the ceramic tube to connect the electrode sheet, the first positive and first negative electrodes of the inner heating element, and the second positive and second negative electrodes of the connecting coil, respectively.

[0017] According to some embodiments of this application, a second external heating coil is placed on the third disk layer. The second external heating coil is located outside the connecting coil. The connecting electrode is connected to the second external heating coil. The second external heating coil is connected to the connecting coil. Then, ceramic raw material powder is filled in, and a fourth disk layer is formed by pre-pressing at room temperature.

[0018] According to some embodiments of this application, the ceramic raw material powder is alumina ceramic raw material or aluminum nitride ceramic raw material.

[0019] According to some embodiments of this application, the hot pressing temperature is 1580-1900℃, the time is 5-48h, and the pressure is 0.1-30MPa.

[0020] One embodiment of this application provides a chemical vapor deposition apparatus, including a ceramic heating plate as described above.

[0021] The heating element of this application includes an inner heating element and an outer heating element. The inner heating element and the outer heating element are independently connected to an external power source. By adjusting the power ratio of the inner heating element and the outer heating element, the inner heating element and the outer heating element can be controlled independently yet in a coordinated manner. This ensures that the outer circular area of ​​the ceramic heating plate will not cause a heat difference with the middle part due to heat dissipation, thus avoiding uneven heat distribution of the ceramic heating plate. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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 exceeding the scope of protection claimed by this application.

[0023] Figure 1 This is a schematic diagram of the inner heating element of the heating element in this application;

[0024] Figure 2 This is a schematic diagram of the external heating element of the heating element in this application;

[0025] Figure 3 This is a schematic diagram of the electrodes connected in this application;

[0026] Figure 4 This is another structural schematic diagram of the external heating element of the heating plate in this application;

[0027] Figure 5 This is a schematic diagram of the ceramic heating plate of this application;

[0028] Figure 6 This is a flowchart of the method for preparing the ceramic heating plate of this application;

[0029] Figure 7 This is a schematic diagram of the mold for preparing the ceramic heating plate of this application.

[0030] in,

[0031] 110 - Inner heating element; 111 - First layer inner heating coil; 112 - Second layer inner heating coil; 113 - Third layer inner heating coil; 114 - Fourth layer inner heating coil; 115 - Fifth layer inner heating coil; 116 - Sixth layer inner heating coil; 120 - Outer heating element; 121 - First outer heating coil; 122 - Connecting coil; 123 - Second outer heating coil; 130 - Connecting electrode;

[0032] 210 - Heating plate; 220 - Ceramic tube; 230 - Electrode plate; 240 - First electrode rod; 250 - Second electrode rod; 260 - Third electrode rod; 270 - Thermocouple;

[0033] 300-Mold; 310-Graphite base; 32-0-Graphite outer mold; 330-Graphite bushing; 340-Graphite pressure head; 350-Gasket; 360-Positioning hole. Detailed Implementation

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] In the description of this application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They 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. Therefore, they should not be construed as limitations on this application.

[0036] In CVD equipment for semiconductor applications, different process gases are used to deposit plasma on the chip surface due to varying chip fabrication requirements. The flow rate and pressure of these process gases vary according to the process specifications. When the pressure is low, the difference between the inner and outer rings of the heating plate is minimal. However, when the pressure is high, the outer ring temperature drops significantly, resulting in a larger temperature difference across the plate. To address this temperature difference caused by different processes, individually designed heating plates with varying heating wire distributions can be used for various equipment and processes. However, this increases costs and significantly reduces the interchangeability of heating plates. Furthermore, different manufacturers produce... CVD equipment cannot be made exactly the same. The gas inlet and outlet positions are not exactly the same, which will cause slight differences in the temperature of the heating plate. Since the heating plate is prepared for the chip deposition process, small changes in heating will be significantly reflected in the deposition thickness. Therefore, it is necessary to control the two zones. Usually, this involves adjusting the power supply current ratio of the inner and outer rings. Under normal circumstances, the inner and outer rings are relatively uniform in temperature when the ratio is 1:1. When the inner ring is relatively cold, the ratio needs to be adjusted to 0.9:1 to increase the power supply to the inner ring, thereby raising the temperature and achieving the purpose of temperature uniformity.

[0037] The heating element of this invention has two structures. One structure has an upper heating element comprising the inner and outer heating elements, with the lower heating element serving only a connecting function. The other structure has an upper layer comprising the inner and outer heating elements, a lower layer comprising the outer heating element, and a connecting coil in the middle of the lower layer. Both the upper and lower layers have external heating coils, which provide reinforcement. See details below. Figure 1 and Figure 2 The upper layer has inner and outer heating elements, while the lower layer only serves as a connection. Figure 1 and Figure 4 It consists of two layers of evenly spaced outer heating elements, which enhance the heating effect on the outer ring.

[0038] Example 1

[0039] like Figure 1 and Figure 2 As shown, this embodiment provides a heating element for fabricating a high-temperature, high-uniformity two-zone ceramic heating plate for use in semiconductor chemical vapor deposition equipment. The heating element includes an inner heating element 110 and an outer heating element 120.

[0040] The inner heating element 110 includes multiple layers of inner heating coils arranged and connected sequentially from the inside out. Each inner heating coil is basically circular. The number of inner heating coil layers can be set according to requirements; in this embodiment, there are six inner heating coil layers. Specifically, the first inner heating coil 111, the second inner heating coil 112, the third inner heating coil 113, the fourth inner heating coil 114, the fifth inner heating coil 115, and the sixth inner heating coil 116 are arranged sequentially from the inside out. The first inner heating coil 111 is connected to the second inner heating coil 112, the second inner heating coil 112 is connected to the third inner heating coil 113, the third inner heating coil 113 is connected to the fourth inner heating coil 114, the fourth inner heating coil 114 is connected to the fifth inner heating coil 115, and the fifth inner heating coil 115 is connected to the sixth inner heating coil 116. The two ends of the first inner heating coil 111 at the center of the inner heating element 110 are respectively connected to the first positive electrode and the first negative electrode. The first positive electrode and the first negative electrode are respectively connected to the electrode rod to supply power to the internal heating element 110.

[0041] The external heating element 120 includes a first external heating coil 121 and a connecting coil 122. The first external heating coil 121 and the inner heating element 110 are disposed on the same horizontal plane, located outside the inner heating element 110. The connecting coil 122 is disposed on the lower layer of the inner heating element 110, that is, the inner heating element 110 and the first external heating coil 121 are located on the upper layer, and the connecting coil 122 is located on the lower layer. The first external heating coil 121 is connected to the connecting coil 122, and the two ends of the connecting coil 122 are respectively connected to the second positive electrode and the second negative electrode. The connecting coil 122 only serves as an electrical connection and does not participate in heating.

[0042] In this embodiment, the connecting coil 122 is bent into multiple symmetrical arcs, wherein the two ends of the central arcs are respectively connected to the second positive electrode and the second negative electrode. The second positive electrode and the second negative electrode are respectively connected to the electrode rod to supply power to the external heating element 120. The connecting coil 122 can also be configured in other shapes as needed; this application does not limit the shape of the connecting coil 122.

[0043] like Figure 3 As shown, in this embodiment, the first external heating coil 121 located on the upper layer and the connecting coil 122 located on the lower layer are connected by the connecting electrode 130.

[0044] In this embodiment, the inner heating element 110 and the outer heating element 120 are independently connected to an external power source. By adjusting the power ratio of the inner heating element and the outer heating element, the inner heating element and the outer heating element become an independent and / or coordinated whole, ensuring that the outer circular area of ​​the ceramic heating plate will not cause a heat difference with the middle part due to heat dissipation, thus avoiding uneven heat distribution of the ceramic heating plate.

[0045] If the ratio of internal to external current cannot be adjusted, the temperature difference will be a fixed value, and the uniformity of the heating plate cannot be guaranteed by adjustment.

[0046] Under normal circumstances, with a 1:1 ratio, the inner and outer heating coils will have relatively uniform temperatures. When the inner heating coil is relatively cold, the ratio needs to be adjusted to 0.9:1 to increase the power supply to the inner heating coil, thereby raising its temperature and achieving temperature uniformity.

[0047] When the current ratio of the inner and outer heating coils is 1:0.65, the temperature difference between them is 6℃; when the ratio is 1:0.68, it is 5.4℃; when the ratio is 1:0.72, it is 5.25℃; and for a single zone, the temperature difference is 8℃. A smaller temperature difference results in a more uniform film deposition thickness on the chip surface. The current ratio between the inner and outer heating coils corresponds to the temperature difference between them. Adjusting the current ratio reduces the temperature difference between the inner and outer heating elements, ensuring uniform temperature distribution.

[0048] According to an optional technical solution of this application, the heating element is a molybdenum or tungsten heating element with a thickness of 0.1-0.5mm, or a spring-type heating element can be used. The different thicknesses and diameters in the two different heating methods are mainly to meet the requirements of different thermal resistances in order to provide an operating temperature of 350-700℃.

[0049] The second inner heating coil 112, the third inner heating coil 113, the fourth inner heating coil 114, the fifth inner heating coil 115, and the sixth inner heating coil 116 are all approximately circular, and the heating wires all extend in a serpentine shape.

[0050] Optionally, in this embodiment, the wire diameter of the first layer inner heating coil 111 is 0.5-2.5mm, and the wiring diameter is 1-60mm. The wire diameter of the second layer inner heating coil 112 is 1-3mm, and the wiring diameter is 40-100mm. The distance between the inner endpoints of adjacent radial heating wires of the second layer inner heating coil 112 is 1-6mm. The wire diameter of the third layer inner heating coil 113 is 2-4mm, and the wiring diameter is 80-110mm. The distance between the inner endpoints of adjacent radial heating wires of the third layer inner heating coil 113 is 2-7mm. The wire diameter of the fourth layer inner heating coil 114 is 2-4mm, and the wiring diameter is 130-190mm. The distance between the inner endpoints of adjacent radial heating wires of the fourth layer inner heating coil 114 is 4-6mm. The fifth-layer inner heating coil 115 has a wire diameter of 2-4mm and a wiring diameter of 170-240mm. The distance between the inner ends of adjacent radial heating wires of the fifth-layer inner heating coil 115 is 7-10mm. The sixth-layer inner heating coil 116 has a wire diameter of 2-4mm and a wiring diameter of 220-270mm. The distance between the inner ends of adjacent radial heating wires of the sixth-layer inner heating coil 116 is 4-6mm.

[0051] The first external heating coil 121 is approximately circular in shape and is located outside the sixth inner heating coil 116. The heating wire of the first external heating coil 121 extends in a serpentine shape with a wire diameter of 2-4 mm and a wiring diameter of 250-320 mm. The distance between the inner ends of adjacent radial heating wires is 2-5 mm.

[0052] Example 2

[0053] like Figure 4 As shown, the heating element in this embodiment is a further improvement on the basis of embodiment 1. The difference is that the heating element in this embodiment, the outer heating element 120, further includes a second outer heating coil 123.

[0054] The second external heating coil 123 is disposed below the first external heating coil 121, and is located outside the connecting coil 122. The second external heating coil 123 and the connecting coil 122 are both located on the lower layer. The connecting coil 122 connects to the second external heating coil 123, and the second external heating coil 123 connects to the first external heating coil 121. In this embodiment, the first external heating coil 121 and the second external heating coil 123 are connected via a connecting electrode 130. By separately arranging the external heating coils at the top and bottom, it is more advantageous to control the temperature of the outer circumferential region of the ceramic heating plate.

[0055] Optionally, the second external heating coil 123 is approximately circular in shape, and the heating wire of the second external heating coil 123 extends in a serpentine manner with a wire diameter of 2-4 mm and a wiring diameter of 220-330 mm. The distance between the inner ends of adjacent radial heating wires is 2-5 mm.

[0056] Optionally, more external heating coils may be provided between the connecting coil 122 and the second external heating coil 123 to further enhance the heating capacity of the heating element.

[0057] Example 3

[0058] like Figure 5 As shown, this embodiment provides a ceramic heating plate 200. The ceramic heating plate 200 includes the heating element as described above. In this embodiment, the ceramic heating plate 200 includes a heating plate body 210, and the heating element is disposed in the heating plate body 210.

[0059] In one optional embodiment, the ceramic heating plate 200 further includes a ceramic tube 220, an electrode plate 230, and electrode rods. The ceramic tube 220 is connected to the lower surface of the heating plate body 210. The electrode plate 230, serving as a radio frequency electrode, is disposed within the heating plate body 210, located above the heating plate. Multiple electrode rods pass through the ceramic tube 220 and are respectively connected to the electrode plate 230 and the heating plate.

[0060] Furthermore, the heating plate 210 is formed by hot pressing a pre-pressed first plate layer, a second plate layer, a third plate layer, and a fourth plate layer. The first, second, third, and fourth plate layers are arranged vertically in sequence. Electrode plates 230 are disposed within the second plate layer. The inner heating plate 110 and the first outer heating coil 121 of the heating plate are disposed within the third plate layer, and the connecting coil 122 of the heating plate is disposed within the fourth plate layer. A ceramic tube 220 is connected to the surface of the fourth plate layer.

[0061] Furthermore, the second external heating coil 123 of the heating element is disposed within the fourth disk layer.

[0062] The heating plate 210 has multiple connection holes that expose the electrode sheet 230 and the first positive electrode, first negative electrode, second positive electrode, and second negative electrode of the heating plate. In this embodiment, there are five electrode rods. Two first electrode rods 240 pass through the ceramic tube 220 and extend into the corresponding connection holes, connecting to the first positive electrode and the first negative electrode of the inner heating plate 110, respectively. Two second electrode rods 250 pass through the ceramic tube 220 and extend into the corresponding connection holes, connecting to the second positive electrode and the second negative electrode on the connecting coil, respectively. A third electrode rod 260 passes through the ceramic tube 220 and extends into the corresponding connection hole, connecting to the electrode sheet 230. The heating plate 210 is also connected to a thermocouple 270 for temperature measurement.

[0063] In this embodiment, the electrode sheet 230 can be a metal mesh. The shape of the metal mesh is a square mesh or a hexagonal mesh of uniform size, and the mesh thickness is 0.1-0.5mm. The metal mesh needs to be acid-treated and then cleaned.

[0064] like Figure 6 As shown, this embodiment provides a method for preparing a ceramic heating plate, including the following steps:

[0065] S101. Pre-press ceramic raw material powder at room temperature to form the first disc layer. In this step, the pre-pressing pressure on the press is 0.1-30MPa, and the holding time is 5-30min.

[0066] S102. Place electrode sheets on the first disk layer, then fill with ceramic raw material powder, and pre-press at room temperature to form the second disk layer. In this step, the pre-pressing pressure on the press is 0.1-30 MPa, and the holding time is 5-30 min.

[0067] S103. Place the inner heating element and the first outer heating coil on the second disc layer, fill with ceramic raw material powder, and pre-press at room temperature to form the third disc layer. The first outer heating coil is connected to a connecting electrode. In this step, the pre-pressing pressure on the press is 0.1-30 MPa, and the holding time is 5-30 min.

[0068] In this step, a specific mold can be used for pre-pressing to expose the connecting electrode to which the first external heating coil is connected.

[0069] In another approach, the third disk layer is pre-pressed into a blank using ceramic raw material powder, and connection holes corresponding to the connecting electrodes are made on the blank. Then, the blank is placed on the second disk layer as the third disk layer.

[0070] S104. Place the connecting coil on the third disc layer, connect the connecting electrode to the connecting coil, then fill with ceramic raw material powder, and pre-press at room temperature to form the fourth disc layer. In this step, the pre-pressing pressure on the press is 0.1-30MPa, and the holding time is 5-30min.

[0071] When connecting the electrode to its associated components, they can be directly bonded together or bonded together using a metal paste. The metal paste can be a mixture containing 80%-90% molybdenum powder, 1%-20% AlN (aluminum nitride), and 1%-10% organic binder. The molybdenum powder has a particle size of 1-5 μm, the AlN has a particle size of 1-5 μm, and the AlN contains 0.1%-5% additives such as calcium oxide, magnesium oxide, or yttrium oxide. The proportions mentioned in the metal paste are by mass.

[0072] S105. The first, second, third, and fourth disc layers are hot-pressed to form a heated disc. Optionally, in this step, the hot-pressing temperature is 1580-1900℃, the time is 5-48h, and the pressure is 0.1-30MPa.

[0073] S106. Sinter the heating plate and the ceramic tube together. In this step, the sintering temperature is 1000℃-1700℃. This embodiment does not specifically limit the shape of the ceramic tube, but a cylindrical shape is preferred. The material of the ceramic tube is aluminum nitride or aluminum oxide, or a mixture containing the above ceramic raw materials. The preparation method of the ceramic tube is not specifically limited; for example, it can be dry-pressed or statically pressed into a tubular shape and sintered at atmospheric pressure.

[0074] S107. Pass multiple electrode rods through the ceramic tube and connect them to the electrode sheet, the first positive and the first negative electrode of the inner heating plate, and the second positive and the second negative electrode of the coil to form a ceramic heating plate.

[0075] Optionally, the ceramic raw material powder is either alumina ceramic raw material or aluminum nitride ceramic raw material. Aluminum nitride ceramic raw material generally refers to a mixture of aluminum nitride powder with one or more of the following: yttrium oxide powder, calcium oxide powder, magnesium oxide powder, and lithium oxide powder. Alumina ceramic raw material generally refers to a mixture of alumina powder with one or more of the following: yttrium oxide powder, calcium oxide powder, magnesium oxide powder, and lithium oxide powder.

[0076] In this embodiment, the hot-pressing temperature of the aluminum nitride heating plate is 1700℃-1900℃, and the hot-pressing temperature of the alumina heating plate is 1580℃-1650℃. The sintering temperature of the aluminum nitride ceramic tube connected to the heating plate is 1500℃-1700℃. The sintering temperature of the alumina ceramic tube connected to the heating plate is 1000℃-1550℃.

[0077] In one alternative embodiment, before forming the fourth disk layer, the method further includes placing a second external heating coil on the third disk layer. The second external heating coil is located outside the connecting coil, and the connecting electrode is connected to the second external heating coil. The second external heating coil is connected to the connecting coil. Then, ceramic raw material powder is filled in, and the fourth disk layer is formed by pre-pressing at room temperature.

[0078] like Figure 7 As shown, the mold 300 for preparing the heating plate in this embodiment includes: a graphite base 310, a graphite outer mold 320, a graphite bushing 330, and a graphite pressure head 340.

[0079] The shape of the graphite base 310 is not specifically limited; it can be square or round, but round is preferred.

[0080] The graphite outer mold 320 is disposed on the graphite base 310. In this embodiment, the shape of the graphite outer mold 320 is not specifically limited. It can be annular or circular in the middle and square on the outside. Annular is preferred.

[0081] The graphite bushing 330 is disposed on the graphite base 310 and located inside the graphite outer mold 320. The graphite bushing 330 is placed on the graphite base 310 and fits against the inner wall of the graphite outer mold 320. The inner diameter of the graphite bushing 330 matches the outer diameter of the heating plate.

[0082] The graphite pressure head 340 is used to transmit pressure to the heating plate during hot pressing.

[0083] Optionally, the mold 300 can produce multiple heating plates at one time, with adjacent heating plates separated by a spacer 350.

[0084] The aforementioned mold 300 achieves final demolding by setting different structures with different coefficients of thermal expansion, as follows: the coefficient of thermal expansion of the graphite bushing 330 is 2-3 × 10⁻⁶. -6 / k, the coefficient of thermal expansion of the graphite outer mold 320 should be close to 0.

[0085] In one alternative, the graphite base 310 is also provided with a positioning hole 360 ​​for easy positioning.

[0086] Example 4

[0087] Another method for preparing a ceramic heating plate in this embodiment differs from the method in Embodiment 3 in that it does not include steps S105 and S106, but includes steps prior to step S107:

[0088] S108. Place ceramic tubes on the fourth plate layer and then perform hot pressing.

[0089] In this step, the hot-pressing temperature is 1580-1900℃, such as 1580℃, 1800℃, or 1900℃, the time is 5-48 hours, such as 5 hours, 10 hours, 35 hours, or 48 hours, and the pressure is 0.1-30 MPa, such as 0.1 MPa, 10 MPa, 15 MPa, 20 MPa, or 30 MPa. Preferably, the hot-pressing temperature is 1650-1800℃, the time is 10-30 hours, and the pressure is 5-20 MPa. Specifically, the hot-pressing temperature is 1700℃, the time is 25 hours, and the pressure is 20 MPa. This embodiment does not specifically limit the shape of the ceramic tube, but a cylindrical shape is preferred. The material of the ceramic tube is aluminum nitride or aluminum oxide, or a mixture containing the above ceramic raw materials. The preparation method of the ceramic tube is not specifically limited; for example, it can be dry-pressed or statically pressed into a tubular shape and sintered at normal pressure.

[0090] The processing method of the ceramic heating plate in this embodiment involves pre-pressing the ceramic raw material powder at room temperature, pre-forming the electrode sheet and heating sheet, and then hot-pressing them with the fired ceramic tube to form the ceramic heating plate in one step, followed by a single high-temperature firing at 1580-1900℃. Since the electrode sheet and heating sheet materials are both high-temperature metals, commonly tungsten and molybdenum, during repeated heating, secondary diffusion of the metal into the ceramic can form some metal-containing compounds (mainly carbides or nitrides). This increases the resistance value, making it difficult to precisely control the resistance and causing a deviation from the actual designed resistance. Consequently, the heat generated by the heating plate cannot be generated according to the predetermined design, resulting in poor thermal uniformity of the heating plate and a decrease in uniformity during chip growth. Furthermore, diffusion from the electrode sheet to nearby ceramics can easily cause a decrease in surface ceramic resistance, and applying high voltage to the electrode sheet increases the possibility of surface ceramic breakdown. Therefore, a single high-temperature firing avoids the repeated high-temperature processes that easily cause changes in the internal resistance of the heating plate, thereby improving the thermal uniformity and service life of the ceramic heating plate.

[0091] Specifically, normal pre-pressing after powder application cannot guarantee the flatness and parallelism of the heating element due to the limited flowability of the powder. Furthermore, the position of the heating element can easily change when powder is applied and pre-pressed again after the heating element has been placed. Therefore, the following optimization scheme is proposed based on these factors:

[0092] Aluminum nitride granulated powder with the same formula was first pressed into shape and then cold isostatically pressed to obtain aluminum nitride ceramic green bodies with strength suitable for processing. The aluminum nitride ceramic green bodies were then machined with corresponding grooves according to the shape of the heating element. The adhesive was removed at 500-600℃. The heating element was then placed on the adhesive-removed green body and transferred to a mold for pre-pressing. Because the green body was pre-processed, the flatness and parallelism can be guaranteed within ±0.01mm. The heating element was placed in the pre-machined groove, the groove depth being the same as or less than the thickness of the heating element. This ensures the heating element has sufficient support, preventing errors in its placement and movement during the pressing process. This method also better ensures the purity of the aluminum nitride material in contact with the heating element. If powder is directly filled and pre-smoothed, other impurities, especially carbon, are easily introduced during the smoothing process. Carbon readily reacts with tungsten and molybdenum materials, thereby changing the material's resistance and affecting the uniformity of the final heating plate's resistance.

[0093] If aluminum nitride ceramic plates are used in this process, the resistivity of the aluminum nitride material itself will decrease due to repeated sintering of the aluminum nitride ceramic plates. This will cause leakage current to interfere with each other between heating wires in different layers. In addition, it will affect the electrode plates, causing current to leak from the electrode plates to the surface of the equipment and the wafer surface, thus making the heating plate unusable.

[0094] Example 5

[0095] This embodiment provides a chemical vapor deposition apparatus, including the ceramic heating plate described above.

[0096] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. Furthermore, any changes or modifications made by those skilled in the art based on the ideas of this application, and on the specific implementation methods and application scope of this application, are all within the scope of protection of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A heating element for a ceramic heating plate, characterized in that, The heating element includes an inner heating element and an outer heating element, which are independently connected to an external power source. The inner heating element includes an inner heating coil, and the outer heating element includes an outer heating coil. The temperature difference between the inner heating element and the outer heating element is reduced by adjusting the current ratio of the inner heating coil and the outer heating coil. The inner heating element includes multiple layers of inner heating coils arranged sequentially from the inside out and connected together. The two ends of the first layer of inner heating coils are respectively connected to a first positive electrode and a first negative electrode. The outer heating element includes a first outer heating coil and a connecting coil. The first outer heating coil is located outside the inner heating element and is connected to the connecting coil. The two ends of the connecting coil are respectively connected to a second positive electrode and a second negative electrode. The first outer heating coil located in the upper layer and the connecting coil located in the lower layer are connected through a connecting electrode. External heating coils are respectively arranged at the top and bottom. The second external heating coil is arranged below the first external heating coil. The second external heating coil is located outside the connecting coil. The second external heating coil and the connecting coil are located together in the lower layer. The connecting coil is connected to the second external heating coil, and the second external heating coil is connected to the first external heating coil.

2. The heating element according to claim 1, characterized in that, The first positive electrode and the first negative electrode are respectively connected to the electrode rod to supply power to the internal heating element.

3. The heating element according to any one of claims 1-2, characterized in that, The heating element is made of molybdenum or tungsten with a thickness of 0.1-0.5 mm, or a spring-type heating element is used to provide an operating temperature of 350-700℃.

4. The heating element according to claim 1, characterized in that, The heating element further includes an upper heating element with an inner heating element and an outer heating element, and a lower heating element that only serves as a connection; or an upper heating element with an inner heating element and an outer heating element, a lower heating element with an outer heating element, a connecting coil in the middle of the lower layer, and an outer heating coil in both the upper and lower layers.

5. A ceramic heating plate comprising a heating element as described in any one of claims 1-4, characterized in that, include: Electrode plates are disposed in the ceramic heating plate; A ceramic tube is connected to the ceramic heating plate; An electrode rod passes through the ceramic tube and connects to the electrode plate and the heating plate, respectively.

6. The ceramic heating plate according to claim 5, characterized in that, Two first electrode rods pass through the ceramic tube and extend into corresponding connection holes, respectively connecting to the first positive electrode and the first negative electrode of the inner heating element; two second electrode rods pass through the ceramic tube and extend into corresponding connection holes, respectively connecting to the second positive electrode and the second negative electrode on the connecting coil; a third electrode rod passes through the ceramic tube and extends into corresponding connection holes, connecting to the electrode sheet.

7. The ceramic heating plate according to claim 5, characterized in that, The ceramic heating plate is formed by hot pressing a pre-pressed first plate layer, a second plate layer, a third plate layer, and a fourth plate layer; the electrode sheet is disposed in the second plate layer; the inner heating sheet and the first outer heating coil of the heating plate are disposed in the third plate layer, and the connecting coil of the heating plate is disposed in the fourth plate layer.

8. The ceramic heating plate according to claim 7, characterized in that, The second external heating coil of the heating element is disposed within the fourth disk layer.

9. The ceramic heating plate according to claim 5, characterized in that, The ceramic heating plate is provided with multiple connection holes to expose the electrode sheet and the first positive electrode, first negative electrode, second positive electrode and second negative electrode of the heating plate. One end of each of the multiple electrode rods extends into the connection holes and connects to the first positive electrode, first negative electrode, second positive electrode and second negative electrode of the electrode sheet and the heating plate.

10. A method for preparing a ceramic heating plate as described in any one of claims 5-9, characterized in that, Including the following steps: The first disc body layer is formed by pre-pressing ceramic raw material powder at room temperature. Electrode sheets are placed on the first disk layer, ceramic raw material powder is filled in, and the second disk layer is formed by pre-pressing at room temperature. An inner heating element and a first outer heating coil are placed on the second disk layer, and ceramic raw material powder is filled in. The third disk layer is formed by pre-pressing at room temperature. The first outer heating coil is connected to a connecting electrode. A connecting coil is placed on the third disk layer, the connecting electrode is connected to the connecting coil, ceramic raw material powder is filled, and the fourth disk layer is formed by pre-pressing at room temperature. The first disk layer, the second disk layer, the third disk layer, and the fourth disk layer are hot-pressed to form a heating disk. The heating plate and the ceramic tube are sintered together; multiple electrode rods are passed through the ceramic tube and connected to the electrode sheet, the first positive and first negative electrodes of the inner heating sheet, and the second positive and second negative electrodes of the coil, respectively.

11. The method for preparing the ceramic heating plate according to claim 10, characterized in that, Before filling with ceramic raw material powder and pre-pressing at room temperature to form the fourth disk layer, the process further includes: placing a second external heating coil on the third disk layer, the second external heating coil being located outside the connecting coil, the connecting electrode being connected to the second external heating coil, and the second external heating coil being connected to the connecting coil.

12. The method for preparing the ceramic heating plate according to claim 11, characterized in that, The ceramic raw material powder is alumina ceramic raw material or aluminum nitride ceramic raw material. The ceramic raw material powder is pre-pressed at room temperature, and the electrode sheet and the heating sheet are pre-formed. Then, the ceramic heating plate is formed by hot pressing with the fired ceramic tube in one step and then fired at a high temperature of 1580-1900℃.

13. The method for preparing the ceramic heating plate according to claim 11, characterized in that, The hot pressing temperature is 1580-1900℃, the time is 5-48h, and the pressure is 0.1-30MPa.

14. The method for preparing the ceramic heating plate according to claim 11, characterized in that, Aluminum nitride granulated powder with the same formula was first pressed into shape and then cold isostatically pressed to obtain an aluminum nitride ceramic green body with strength suitable for processing. The aluminum nitride ceramic green body was processed with corresponding grooves according to the shape of the heating element, and the adhesive was removed at 500-600℃. Then the heating element was placed on the green body with the adhesive removed and transferred into the mold for pre-pressing.

15. The method for preparing the ceramic heating plate according to claim 14, characterized in that, The mold for preparing the heating plate includes a graphite base, a graphite outer mold, a graphite bushing, and a graphite pressure head. The mold achieves final demolding by setting various structures with different expansion coefficients.

16. A chemical vapor deposition apparatus, characterized in that, Includes the ceramic heating plate as described in any one of claims 5-9.

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