Heater and manufacturing process thereof

Abstract

The heater comprises an upper layer, a middle layer, a lower layer and a supporting shaft, the heat conductivity of the upper layer is far larger than that of the lower layer and the supporting shaft, and heat generated by a heating resistance wire in the using process is low in transmission speed through the lower layer and the supporting shaft; the loss amount of the lower layer and the supporting shaft is reduced; the middle upper layer is high in heat conductivity and small in thickness, the heat transfer speed is high, and the surface temperature uniformity of the upper layer of the disc is good; according to the manufacturing method of the heater, the heat conductivity of the upper layer, the middle layer, the lower layer and the supporting shaft is controlled by controlling the type and the dosage of the sintering aid, the thickness of the upper layer, the middle layer and the lower layer and the wall thickness of the supporting shaft are controlled, and the difference value between the highest temperature point and the lowest temperature point of the upper surface of the heating disc does not exceed 10 DEG C; therefore, when the heater disclosed by the invention is used for carrying out a PECVD process, the thickness of a formed film is relatively uniform.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor device manufacturing, and particularly relates to a heater and a manufacturing process thereof. Background Art

[0002] In the process of manufacturing semiconductor chips, the PECVD (Plasma Enhanced Chemical Vapor Deposition) process is usually used to form a thin film. In the PECVD process, various gases need to be injected into a vacuum chamber to ionize them to form a plasma, and the reaction occurs at a high temperature to form a thin film on the wafer. Therefore, in a CVD device, the component for placing the wafer needs to have a heating function, which is called a heater.

[0003] Currently, in relatively advanced manufacturing processes, aluminum nitride is used as the material for the heater. Aluminum nitride has good plasma etching resistance, high thermal conductivity, and a thermal expansion coefficient similar to that of the wafer. The structure of the aluminum nitride heater is usually as Figure 1 shown, including a disk for carrying the wafer and a support shaft below the disk. A resistance wire for heating and an RF electrode layer for controlling the plasma are buried inside the disk.

[0004] The manufacturing process of the above heater is as follows:

[0005] S1. Prepare aluminum nitride powder, which contains a certain amount of sintering aids such as Y2O3 and CaO and a binder;

[0006] S2. Add the aluminum nitride powder into a mold, and perform material densification molding through dry pressing or isostatic pressing to obtain the lower green body of the disk;

[0007] S3. Take out the lower green body from the mold, make a groove in the lower green body and place the heating resistance wire in the groove;

[0008] S4. After the heating resistance wire is placed in the groove, put the lower green body back into the mold, continue to add aluminum nitride powder into the mold, and perform material densification molding through dry pressing or isostatic pressing to obtain the middle and lower green body of the disk;

[0009] S5. Place the RF electrode on the middle layer, continue to add aluminum nitride powder into the mold, and perform material densification molding through dry pressing or isostatic pressing to obtain a complete disk green body;

[0010] S6. Debind the disk green body in an atmospheric environment to remove the binder therein. The debinding temperature is 300 - 800 °C, and the time is 1 - 12 hours. Put the debound product into a sintering furnace and sinter it in a nitrogen atmosphere. The sintering temperature is 1600 - 1900 °C, and the sintering time is 2 - 24 hours;

[0011] S7. Machine process the sintered disk to obtain the required shape and size, and expose the joints of the heating resistance wire and the RF electrode;

[0012] S8. Fix a wire at the joints of the heating resistance wire and the RF electrode by vacuum brazing to connect to the power supply;

[0013] S9. Produce a green body of the support shaft by isostatic pressing, and rough machine process the green body to form the required shape;

[0014] S10. Debind and sinter the green body of the support shaft according to the steps in S6, and then machine process it to obtain the required shape and size of the support shaft;

[0015] S11. Weld the disk obtained in S8 and the support shaft obtained in S10 together;

[0016] S12. After machine processing the welded product to obtain the required shape and size, obtain the required floating point structure on the surface of the product by masking and sandblasting.

[0017] Disadvantages / Deficiencies of the Prior Art:

[0018] For the aluminum nitride heater obtained through the above process, the thermal conductivity of the heating disk and the support shaft is relatively uniform. Therefore, during use, a considerable part of the heat generated by the heating resistance wire will be dissipated through the lower layer of the disk and the support shaft. In addition, since the buried position of the heating resistance wire cannot be precisely controlled, the uniformity of the heat generated at each part of the heater cannot be guaranteed when generating heat. At the same time, during the CVD process, cold gas continuously enters the cavity, and the non-uniformity of the gas flow will also cause non-uniform heat dissipation of the heater. Therefore, when the thermal conductivity of the heating disk is relatively low, the heat diffusion speed is slow, resulting in poor surface temperature uniformity of the heater (temperature deviation > 10 °C), thereby causing non-uniformity of the film thickness formed by the PECVD process. Summary of the Invention

[0019] To overcome the above disadvantages, the purpose of the present invention is to provide a heater with less heat loss during heating and good surface temperature uniformity and its manufacturing process.

[0020] To achieve the above purpose, the technical solution adopted by the present invention is: a heater, including a heating disk, a radio frequency electrode, a heating resistance wire and a support shaft, and the support shaft is arranged at the bottom of the heating disk to support the heating disk;

[0021] The heating disk sequentially includes an upper layer, a middle layer and a lower layer from top to bottom in the vertical direction, and the materials of the upper layer, the middle layer, the lower layer and the support shaft are all aluminum nitride;

[0022] The heating resistance wire is embedded in the intermediate layer, and the radio frequency electrode is embedded between the intermediate layer and the upper layer. Terminals are provided on both the heating resistance wire and the radio frequency electrode, and the terminals are used to connect wires for connection to an external power supply, where

[0023] The thicknesses of the upper layer, the intermediate layer, and the lower layer gradually increase from top to bottom in the vertical direction. Among them, the thickness of the lower layer is more than twice the thickness of the intermediate layer;

[0024] The thermal conductivities of the upper layer, the intermediate layer, the lower layer, and the support shaft gradually decrease from top to bottom in the vertical direction. Among them, the thermal conductivity of the upper layer is more than twice the thermal conductivity of the lower layer, and the thermal conductivity of the intermediate layer is the same as that of the upper layer.

[0025] When the heating resistance wire of the heater provided by the present invention is energized and heated, due to the low thermal conductivity of the lower layer of the disc and the support shaft, the large thickness of the lower layer of the disc, and the small wall thickness of the support shaft, the heat generated by the resistance wire is transferred slowly through the lower layer and the support shaft, and the heat dissipation through the lower layer and the support shaft is reduced; while the upper and middle layers have higher thermal conductivity and smaller thickness, and the heat transfer speed is faster, so that the temperature uniformity on the upper surface of the disc is better. Therefore, when the PECVD process is carried out using this heater, the thickness of the formed film is relatively uniform.

[0026] Further, the thickness of the upper layer is 1 - 1.5 mm, and the thermal conductivity ≥ 180 W / mK;

[0027] The thickness of the intermediate layer is 4 - 6 mm, and the thermal conductivity ≥ 180 W / mK;

[0028] The thickness of the lower layer ≥ 12 mm, and the thermal conductivity ≤ 100 W / mK;

[0029] The distance between the upper surface of the heating resistance wire and the upper surface of the intermediate layer, and the distance between the lower surface of the heating resistance wire and the lower surface of the intermediate layer are both 1 ± 0.2 mm;

[0030] The material of the support shaft is aluminum nitride, the outer diameter of the support shaft is 30 - 40 mm, the wall thickness is 2 - 3 mm, and the thermal conductivity ≤ 100 W / mK.

[0031] For the heater with such a structure, during the heating process, the temperature difference between the highest point and the lowest point on the upper surface of the heating disc always remains within 10°C.

[0032] Further, the material of the heating resistance wire is molybdenum.

[0033] The materials of the heating resistance wires are all molybdenum. The thermal expansion coefficient of molybdenum is close to that of aluminum nitride, which can avoid cracking of aluminum nitride caused by thermal expansion and contraction during use.

[0034] Furthermore, the material of the radio frequency electrode is molybdenum.

[0035] The material of the RF electrodes is molybdenum, which has a thermal expansion coefficient close to that of aluminum nitride, and can prevent aluminum nitride from cracking due to thermal expansion and contraction during use.

[0036] The present invention also provides a method for manufacturing the above-mentioned heater, characterized in that it comprises the following steps:

[0037] S1. Preparation of aluminum nitride powder of the middle layer and the upper layer;

[0038] S2. Preparation of an intermediate layer green body, embedding the heating resistance wire in the intermediate layer green body, adding the aluminum nitride powder obtained in S1 into the mold, and forming a disc green body with a thickness of 5 to 7 mm by dry pressing, taking the disc green body out of the mold, digging a groove with a depth of 2 to 4 mm therein, placing the heating resistance wire made of molybdenum into the dug groove, and providing a terminal for connecting to the wire at the center of the heating resistance wire; putting the disc green body back into the mold, and continuing to add the aluminum nitride powder obtained in S1 into the mold, forming a disc green body with a thickness of 8 to 10 mm and embedded with the heating resistance wire by dry pressing, and then taking the disc green body out of the mold, and removing the periphery and the upper and lower surfaces thereof by a machining center, so that the total thickness of the disc green body is 4 to 6 mm and the distance between the heating resistance wire and the upper and lower surfaces of the disc green body is 1±0.2 mm;

[0039] S3. Preparation of upper raw embryo;

[0040] S4. Defatting the upper and middle layers of raw embryos;

[0041] S5. Production of aluminum nitride powder of the lower layer and the support shaft;

[0042] S6. Preparation of lower green body;

[0043] S7. Production of supporting shaft embryo;

[0044] S8. Defatting of the lower layer of embryos and the supporting axis of embryos;

[0045] S9. Pre-sintering and sintering of the upper green embryo, the middle green embryo, the lower green embryo, and the support shaft green embryo: the upper green embryo, the middle green embryo, and the lower green embryo are stacked from top to bottom and pre-sintered and sintered to form a heating disk, the RF electrode is buried between the upper green embryo and the middle green embryo, and the support shaft green embryo is sintered and pre-sintered;

[0046] S10. Drilling holes in the heating disc and soldering wires;

[0047] S11. The support shaft and the heating disc are welded together and finely processed to obtain a finished heater.

[0048] The heating disk of the heater produced by this method is divided into upper, middle, and lower layers with gradually decreasing thermal conductivities from top to bottom. The lower layer of the heating disk and the support shaft have relatively low thermal conductivities. At the same time, the lower layer has a larger thickness, and heat is not easily conducted through the lower layer and the support shaft. Meanwhile, the middle and upper layers have relatively high thermal conductivities, smaller thicknesses, and the burial position of the heating resistance wire in the middle layer is precisely controlled so that the heating resistance wire is located in the upper half of the heating disk. As a result, heat can be rapidly conducted between the middle and upper layers, improving the uniformity of the surface temperature of the heating disk of the heater, making the difference between the highest and lowest temperatures on the upper surface of the heating disk not exceed 10°C. Therefore, when the PECVD process is carried out using the heater produced by this method, the thickness of the formed thin film is relatively uniform.

[0049] Further, the average particle size of the aluminum nitride powder in step S1 is 50 - 100 μm, and it contains 1 - 3% by weight of a sintering aid and 1 - 5% by weight of a binder.

[0050] The addition amount of the sintering aid with a weight fraction of 1 - 3% can control the thermal conductivity of the aluminum nitride material ≥ 180 W / mK by controlling the content of impurity particles in the material.

[0051] Further, the average particle size of the aluminum nitride powder in step S5 is 50 - 100 μm, and it contains 5 - 10% by weight of a sintering aid and 1 - 5% by weight of a binder.

[0052] The addition amount of the sintering aid with a weight fraction of 5 - 10% can control the thermal conductivity of the aluminum nitride material ≤ 100 W / mK by controlling the content of impurity particles in the material.

[0053] Further, the sintering aid in step S1 is at least one of yttrium oxide, calcium oxide, yttrium fluoride, and calcium fluoride.

[0054] Using one or more of these four sintering aids as the sintering aid for aluminum nitride can adjust its thermal conductivity without affecting other properties of the aluminum nitride material.

[0055] Further, the binder in step S1 is an organic material such as PVA, PVB, or PEG.

[0056] Further, the degreasing in steps S4 and S8 and the sintering and pre-sintering in step S9 are all carried out in a nitrogen atmosphere.

[0057] Using a nitrogen atmosphere for calcination can effectively avoid the occurrence of oxidation reactions, reduce the grain boundary energy of the aluminum nitride material, improve the material structure, making the grain boundaries of the material clear, the crystallinity increased, and the grains uniform.

[0058] Further, the solder used in the brazing in the step S10 is a silver-based solder.

[0059] The silver-based solder has high strength and good plasticity and is suitable for welding at high temperatures. Description of the Drawings

[0060] Figure 1 is a schematic structural diagram of an existing heater;

[0061] Figure 2 is a schematic structural diagram of the heater of the present invention;

[0062] Figure 3 is a schematic diagram of the distribution of the heating resistance wires of the present invention on the heating disc;

[0063] Figure 4 is a distribution diagram of the selected points of the measurement positions for testing the surface temperature uniformity of the heating disc in Embodiment 3.

[0064] In the figure: 1. Heating disc 11. Upper layer 12. Intermediate layer 13. Lower layer 21. Radio frequency electrode 22. First terminal 23. First wire 31. Heating resistance wire 32. Second terminal 33. Second wire 4. Support shaft 41. Side wall of the support shaft Detailed Embodiments

[0065] The following describes in detail the preferred embodiments of the present invention with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making the protection scope of the present invention more clearly defined.

[0066] Refer to the attached Figure 1 As shown, the thermal conductivities of the upper, middle and lower layers of the heating disc of the existing heater and the support shaft are relatively close. Therefore, a considerable part of the heat generated by the heating resistance wire will be dissipated through the lower layer of the disc and the support shaft during use. In addition, since the position where the heating resistance wire is buried cannot be accurately controlled and the thermal conductivity of the disc is only about 100 - 150 W / mK, the heat diffusion speed is slow. Therefore, the surface temperature uniformity of the heater is poor (temperature deviation > 10°C), resulting in non-uniformity of the film thickness formed by the PECVD process.

[0067] Embodiment 1

[0068] Refer to Figure 2, the heater provided in this embodiment is an aluminum nitride heater, including a heating disk 1 and a support shaft 4. Among them, both the heating disk 1 and the support shaft 4 are made of aluminum nitride ceramics. The heating disk 1 sequentially includes an upper layer 11, an intermediate layer 22, and a lower layer 13 from top to bottom in the vertical direction; the upper end of the support shaft 4 is welded to the lower surface of the lower layer 13; a heating resistance wire 31 is embedded in the intermediate layer 22. The heating resistance wire 31 is a molybdenum resistance wire. A first terminal 32 for connecting a first wire 33 is provided on the heating resistance wire 31 so that the heating resistance wire 31 can be connected to an external power source; a radio frequency electrode 21 made of molybdenum is embedded between the upper layer 11 and the intermediate layer 12. A second terminal 22 for connecting a second wire 23 is provided on the radio frequency electrode 21 so that the radio frequency electrode 21 can be connected to an external power source; the thicknesses of the upper layer 11, the intermediate layer 12, and the lower layer 13 gradually increase from top to bottom in the vertical direction. Among them, the thickness of the lower layer 13 is more than twice the thickness of the intermediate layer 12; the thermal conductivities of the upper layer 11, the intermediate layer 12, the lower layer 13, and the support shaft 4 gradually decrease from top to bottom in the vertical direction. Among them, the thermal conductivity of the upper layer 11 is more than twice the thermal conductivity of the lower layer 13, and the thermal conductivities of the intermediate layer 12 and the upper layer 11 are similar. The thermal conductivities of the intermediate layer 12 and the upper layer 11 are relatively high, and the heat generated by the heating resistance wire 31 during the energization process is conducted at a relatively fast rate in the intermediate layer 12 and the upper layer 11, which can improve the uniformity of the surface temperature of the heating disk of the heater. Therefore, when using this heater for the PECVD process, the thickness of the formed thin film is relatively uniform; at the same time, the thermal conductivities of the lower layer and the support shaft are relatively low, and at the same time, the thickness of the lower layer is relatively large, so it is not easy for heat to be conducted through the lower layer and the support shaft, and the amount of heat dissipated by the heating resistance wire during the energization process through the lower layer and the support shaft is relatively small.

[0069] In some other embodiments of the present invention, the thickness of the upper layer 11 of the heating disk 1 of the aluminum nitride heater is 1 - 1.5 mm, and the thermal conductivity ≥ 180 W / mK;

[0070] The thickness of the intermediate layer 12 is 4 - 6 mm, and the thermal conductivity ≥ 180 W / mK;

[0071] The thickness of the lower layer 13 ≥ 12 mm, and the thermal conductivity ≤ 100 W / mK;

[0072] The distance between the upper surface of the heating resistance wire 31 and the upper surface of the intermediate layer 12, and the distance between the lower surface of the heating resistance wire 31 and the lower surface of the intermediate layer 12 are both 1 ± 0.2 mm;

[0073] The outer diameter of the support shaft 4 is 30 - 40 mm, the wall thickness of the side wall 41 of the support shaft is 2 - 3 mm, and the thermal conductivity ≤ 100 W / mK.

[0074] Embodiment 2

[0075] This embodiment provides a method for manufacturing the heater in Embodiment 1. Now, in combination with the ceramic heater provided in Embodiment 1, the method for preparing the ceramic heater in this embodiment will be described in detail.

[0076] S1. Preparation of aluminum nitride powders for the intermediate layer 12 and the upper layer 11: The aluminum nitride powders for the intermediate layer 12 and the upper layer 11 are prepared by spray granulation. The average particle size of the powders is 50 - 100 μm. Among them, yttrium oxide with a weight fraction of 1 - 3% is contained as a sintering aid and 1 - 5% of a binder. The binder is a pvb material, namely polyvinyl butyral.

[0077] S2. Preparation of the green body of the intermediate layer 12: The aluminum nitride powder obtained in S1 is added to a mold, and a disk green body with a thickness of 5 - 7 mm is formed by dry pressing. The disk green body is taken out of the mold, and a groove with a depth of 2 - 4 mm is dug in it. After placing the heating resistance wire 31 made of molybdenum into the dug groove, a first terminal 32 for connecting to a wire is provided on the heating resistance wire 31. The disk green body is put back into the mold, and the aluminum nitride powder prepared in S1 is continuously added to the mold. A disk green body with a thickness of 8 - 10 mm and embedded with the heating resistance wire 12 is formed by dry pressing. Then, the disk green body is taken out of the mold, and its periphery and upper and lower surfaces are removed by a machining center, so that the total thickness of the obtained disk green body is 4 - 6 mm and the distances from the heating resistance wire to the upper and lower surfaces of the disk green body are both 1 ± 0.2 mm.

[0078] S3. Preparation of the green body of the upper layer 11: The aluminum nitride powder prepared in S1 is added to a mold, and a disk green body with a total thickness of 4 - 4.5 mm is formed by dry pressing. After taking it out of the mold, its periphery and surface are removed by a machining center, so that its total thickness is 1 - 1.5 mm.

[0079] S4. Debinding of the green bodies of the upper layer 11 and the intermediate layer 12: The green bodies of the intermediate layer 12 and the upper layer 11 prepared in S2 and S3 are debound in a nitrogen atmosphere to remove the binder therein. The debinding temperature is 600 - 1000 °C, and the time is 48 hours or more. The carbon content in the debound green bodies of the upper layer 11 and the intermediate layer 12 is within 0.1%, and the oxygen content is within 1.5%.

[0080] S5. Preparation of aluminum nitride powders for the lower layer 13 and the support shaft 4: The aluminum nitride powders for the lower layer 13 and the support shaft 4 are prepared by spray granulation. The average particle size of the powders is 50 - 100 microns. Among them, 5 - 10% of yttrium oxide is contained as a sintering aid, and 1 - 5% of pvb material is used as a binder.

[0081] S6. Fabrication of the lower layer 13 green body: Add the aluminum nitride powder obtained in S5 into a mold, and form a disk green body with a thickness of more than 15 mm by dry pressing. Then, use a machining center to remove its periphery and upper and lower surfaces to make its thickness more than 12 mm.

[0082] S7. Fabrication of the support shaft 4 green body: Add the aluminum nitride powder obtained in S5 into the mold for fabricating the support shaft 4, fabricate the support shaft 4 by isostatic pressing, and use a machining center to process and remove the excess parts to make it have dimensions close to the finished product.

[0083] S8. Debinding of the lower layer green body and the support shaft green body: Debind the lower layer green body and the support shaft green body obtained in S6 and S7 in an atmospheric atmosphere to remove the binder therein. The debinding temperature is 300 - 600 °C, and the time is 4 - 12 hours. The carbon content in the debound lower layer green body and support shaft green body is below 0.1%, and the oxygen content is between 2.5 - 3%.

[0084] S9. Pre-sintering and sintering of the upper layer green body, the middle layer green body, the lower layer green body, and the support shaft green body: Stack the debound upper layer green body, middle layer green body, and lower layer green body obtained in S4 and S8 on top of each other from top to bottom, and then put them into a hot press furnace for pre-sintering and sintering.

[0085] Among them, a radio frequency electrode is placed between the middle layer and the upper layer.

[0086] Then, put the support shaft green body into the hot press furnace for pre-sintering and sintering.

[0087] Pre-sintering and sintering conditions of the upper layer green body, the middle layer green body, the lower layer green body, and the support shaft green body:

[0088] Pre-sintering conditions: The pressure is 200 - 400 kgf / cm 2 , the temperature is 1500 - 1600 °C, the time is 2 - 4 hours, nitrogen is introduced into the furnace, and the nitrogen gas pressure is maintained at 2 - 10 KPa.

[0089] Sintering conditions: The pressure is 200 - 400 kgf / cm2, the temperature is 1700 - 1900 °C, the time is 2 - 4 hours, nitrogen is introduced into the furnace, and the nitrogen gas pressure is maintained at 2 - 10 KPa.

[0090] S10. Use a machining center to drill holes in the heating disk obtained after pre-sintering and sintering in S9, so that the ends of the second terminal 32 of the heating resistance wire 31 and the first terminal 22 of the radio frequency electrode 21 are both exposed. Use vacuum brazing with a silver-based solder to brazingly connect the second wire 33 to the end of the second terminal 32 of the heating resistance wire 31, and use vacuum brazing with a silver-based solder to brazingly connect the first wire 23 to the end of the first terminal 22 of the heating resistance wire 21.

[0091] S11. Place the component obtained in step S10 and the support shaft obtained in step S9 together in a hot press furnace for welding; during welding, the pressure is 300 - 600 kgf / cm2, the temperature is 1600 - 1900 °C, the time is 8 - 24 hours, and nitrogen is introduced into the furnace with the nitrogen gas pressure maintained at 2 - 10 KPa.

[0092] Finish machining the component obtained in step S13 using a machining center to obtain the required shape and dimensions.

[0093] In this embodiment, the arrangement of the heating resistance wires in the heating disc is as Figure 3 shown, including a plurality of arc-shaped patterns in a concentric circle shape and linear patterns connecting adjacent arc-shaped patterns to each other.

[0094] Example 3

[0095] In this embodiment, the manufacturing process of the aluminum nitride ceramic heater is as follows:

[0096] S1. Preparation of aluminum nitride powder for the intermediate layer 12 and the upper layer 11: Prepare the aluminum nitride powder for the intermediate layer 12 and the upper layer 11 by spray granulation, with the average particle size of the powder being 50 μm; among them, 1% by weight of yttrium oxide is contained as a sintering aid and 3% of a binder, and the binder is a PEG material, namely polyethylene glycol;

[0097] S2. Preparation of the green body of the intermediate layer 12; Add the aluminum nitride powder obtained in S1 into a mold, and form a disc green body with a thickness of 7 mm by dry pressing. Take out the disc green body from the mold, dig a groove with a depth of 4 mm in it, place the heating resistance wire 31 made of molybdenum into the dug groove, and a first terminal 32 for connecting with a wire is provided on the heating resistance wire 31; put the disc green body back into the mold, continue to add the aluminum nitride powder prepared in S1 into the mold, and form a disc green body with a thickness of 10 mm and embedded with the heating resistance wire 12 by dry pressing. Then take out the disc green body from the mold, and remove its periphery and upper and lower surfaces using a machining center, so that the total thickness of the obtained disc green body is 6 mm and the distance between the heating resistance wire and the upper and lower surfaces of the disc green body is 1 ± 0.2 mm;

[0098] S3. Preparation of the green body of the upper layer 11: Add the aluminum nitride powder prepared in S1 into a mold, and form a disc green body with a total thickness of 4 mm by dry pressing. After taking it out from the mold, remove its periphery and surface using a machining center to make its total thickness 1 mm.

[0099] S4. Degreasing of the upper layer 11 and the intermediate layer 12: The intermediate layer 12 and the upper layer 11 prepared by S2 and S3 are degreased in a nitrogen atmosphere to remove the binder therein, the degreasing temperature is 900 ° C, the time is more than 52 hours, the carbon content of the upper layer 11 and the intermediate layer 12 after degreasing is 0.02%, and the oxygen content is 1.2%;

[0100] S5. Preparation of aluminum nitride powder of the lower layer 13 and the support shaft 4: aluminum nitride powder of the lower layer 13 and the support shaft 4 was prepared by spray granulation, the average particle size of the powder was 70 microns, containing 8% yttrium oxide as a sintering aid, and 2% PEG material as a binder;

[0101] S6 lower layer 13 green production: The aluminum nitride powder obtained in S5 was added to the mold, formed by dry pressing a disc green embryo having a thickness of 18mm, and then removed from the periphery and the upper and lower surfaces by a machining center to a thickness of 13mm;

[0102] S7. Preparation of the green embryo of the support shaft 4: The aluminum nitride powder prepared in S5 is added to the mold for making the support shaft 4, the support shaft 4 is made by isostatic pressing, and the excess part is removed by a machining center to make it have a size close to that of the finished product.

[0103] S8. Degreasing of the lower green embryo and the support shaft green embryo: The lower green embryo and the support shaft green embryo obtained in S6 and S7 were degreased in an atmospheric atmosphere to remove the binder therein, the degreasing temperature was 500 ° C, the time was 8 hours, the carbon content of the lower green embryo and the support shaft green embryo after degreasing was 0.05%, and the oxygen content was 2.8%;

[0104] S9. Pre-sintering and sintering of the upper green embryo, the middle green embryo, the lower green embryo, and the support shaft green embryo: The degreased upper green embryo, the middle green embryo and the lower green embryo obtained in S4 and S8 are stacked together from top to bottom and then placed in a hot press furnace for pre-sintering and sintering;

[0105] Wherein, a radio frequency electrode is placed between the middle layer and the upper layer;

[0106] The support shaft green body is then placed in a hot press furnace for pre-sintering and sintering.

[0107] Pre-sintering and sintering conditions of the upper green embryo, the middle green embryo, the lower green embryo, and the supporting shaft green embryo:

[0108] Pre-sintering conditions: pressure 400kgf / cm2, temperature 1500℃, time 4 hours, nitrogen gas is introduced into the furnace, and the nitrogen pressure is maintained at 5KPa;

[0109] Sintering conditions: pressure is 400 kgf / cm2, temperature is 1800 °C, time is 4 hours, nitrogen gas is introduced into the furnace, and the nitrogen gas pressure is maintained at 5 KPa.

[0110] S10. Use a machining center to drill holes in the heated disk obtained after pre-sintering and sintering in S9, so that the ends of the second terminal 32 of the heating resistance wire 31 and the first terminal 22 of the radio frequency electrode 21 are both exposed. Use vacuum brazing with a silver-based solder to brazing-connect the second wire 33 to the end of the second terminal 32 of the heating resistance wire 31, and use vacuum brazing with a silver-based solder to brazing-connect the first wire 23 to the end of the first terminal 22 of the heating resistance wire 21.

[0111] S11. Place the component obtained in step S10 and the support shaft obtained in step S9 together in a hot pressing furnace for welding; during welding, the pressure is 600 kgf / cm 2 , the temperature is 1800 °C, the time is 16 hours, nitrogen gas is introduced into the furnace, and the nitrogen gas pressure is maintained at 7 KPa.

[0112] Finish-machine the component obtained in step S13 using a machining center to obtain the required shape and dimensions.

[0113] Conduct thermal conductivity tests on the upper, middle, and lower layer materials of the manufactured heater, and the obtained data are shown in Table 1.

[0114] Table 1 Thermal conductivities of the upper, middle, and lower layers of the heated disk

[0115] Position Thermal conductivity Upper layer 208 w / m·S Middle layer 202 w / m·S Lower layer 85 w / m·S Support shaft 78 w / m·S

[0116] Gradually increase the temperature of the upper surface of the manufactured heated disk and select thirteen points on the surface to conduct temperature uniformity tests on the surface, and the obtained data are shown in Table 2. The distribution of the measurement positions is shown in Figure 4 .

[0117] Table 2 Test results of the temperature uniformity of the upper surface of the heated disk

[0118]

[0119]

[0120] As can be seen from Table 2, during the heating process, the temperature uniformity of the upper surface of the heated disk is good, and the difference between the highest temperature point and the lowest temperature point does not exceed 10 °. Therefore, when the PECVD process is carried out using the heater manufactured by the method of the present invention, the thickness of the formed thin film is relatively uniform.

[0121] In other embodiments of the method of the present invention, the sintering aid includes but is not limited to yttrium oxide, and may also be calcium oxide, yttrium fluoride, or calcium fluoride.

[0122] The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it. It is not intended to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A heater, characterized in that, It includes a heating disc, a radio frequency electrode, a heating resistance wire and a support shaft. The support shaft is arranged at the bottom of the heating disc to support the heating disc; The heating disc sequentially includes an upper layer, a middle layer and a lower layer from top to bottom in the vertical direction. The materials of the upper layer, the middle layer, the lower layer and the support shaft are all aluminum nitride; The heating resistance wire is embedded in the middle layer, and the radio frequency electrode is embedded between the middle layer and the upper layer. Terminals are arranged on both the heating resistance wire and the radio frequency electrode. The terminals are used to connect wires for connection to an external power supply, where The thicknesses of the upper layer, the middle layer and the lower layer gradually increase from top to bottom in the vertical direction. Among them, the thickness of the lower layer is more than twice the thickness of the middle layer; The thermal conductivities of the upper layer, the middle layer, the lower layer and the support shaft gradually decrease from top to bottom in the vertical direction. Among them, the thermal conductivity of the upper layer is more than twice the thermal conductivity of the lower layer, and the thermal conductivity of the middle layer is slightly less than the thermal conductivity of the upper layer.

2. The heater according to claim 1, wherein, The thickness of the upper layer is 1 - 1.5 mm, and the thermal conductivity ≥ 180 W / mK; The thickness of the middle layer is 4 - 6 mm, and the thermal conductivity ≥ 180 W / mK; The thickness of the lower layer ≥ 12 mm, and the thermal conductivity ≤ 100 W / mK; The distances between the upper surface of the heating resistance wire and the upper surface of the middle layer, and between the lower surface of the heating resistance wire and the lower surface of the middle layer are both 1 ± 0.05 mm; The material of the support shaft is aluminum nitride. The outer diameter of the support shaft is 30 - 40 mm, the wall thickness is 2 - 3 mm, and the thermal conductivity ≤ 100 W / mK.

3. The heater according to claim 1, characterized in that, The materials of the heating resistance wire and the radio frequency electrode are both molybdenum.

4. A method for manufacturing a heater as described in claims 1-3, characterized in that, It includes the following steps: S1. Preparation of aluminum nitride powder for the middle layer and the upper layer; S2. Preparation of the middle layer green body. Embed the heating resistance wire in the middle layer green body. Add the aluminum nitride powder obtained in S1 into a mold, and make a disc green blank with a thickness of 5 - 7 mm by dry pressing. Take out the disc green blank from the mold, dig a groove with a depth of 2 - 4 mm in it. Place the heating resistance wire made of molybdenum into the dug groove. A terminal for connecting a wire is provided in the central part of the heating resistance wire; put the disc green blank back into the mold, continue to add the aluminum nitride powder prepared in S1 into the mold, and form a disc green blank with a thickness of 8 - 10 mm and embedded with a heating resistance wire by dry pressing. Then take out the disc green blank from the mold, and remove its periphery and upper and lower surfaces with a machining center, so that the total thickness of the obtained disc green body is 4 - 6 mm and the distances between the heating resistance wire and the upper and lower surfaces of the disc green body are both 1 ± 0.2 mm; S3. Preparation of the upper layer green body; S4. Debinding of the upper layer green body and the middle layer green body; S5. Preparation of aluminum nitride powder for the lower layer and the support shaft; S6. Preparation of the lower layer green blank; S7. Preparation of the support shaft green body; S8. Debinding of the lower layer green body and the support shaft green body; S9. Pre-sintering and sintering of the upper green body, middle green body, lower green body, and support shaft green body: The upper green body, middle green body, and lower green body are stacked from top to bottom in sequence for pre-sintering and sintering to form a heating disc. The radio frequency electrode is buried between the upper green body and the middle green body, and the support shaft green body is sintered and pre-sintered. S10. Drilling holes in the heating disc and brazing wires. S11. Welding and combining the support shaft with the heating disc, and obtaining the finished heater through finish machining.

5. The method for manufacturing a heater according to claim 4, characterized in that, In step S1, the average particle size of the aluminum nitride powder is 50 - 100 μm, among which, there are 1 - 3% by weight of sintering aids and 1 - 5% by weight of binders.

6. The method for manufacturing a heater according to claim 4, characterized in that, In step S5, the average particle size of the aluminum nitride powder is 50 - 100 μm, among which, there are 5 - 10% by weight of sintering aids and 1 - 5% by weight of binders.

7. The method for manufacturing a heater according to claim 4, characterized in that, Further, the sintering aids in step S1 are at least one of yttrium oxide, calcium oxide, yttrium fluoride, and calcium fluoride.

8. The method for manufacturing a heater according to claim 4, characterized in that, The binder in step S1 is an organic material such as PVA, PVB, or PEG.

9. The method for manufacturing a heater according to claim 4, wherein The degreasing in step S4, step S8, and the sintering and pre-sintering in step S9 are all carried out in a nitrogen atmosphere.

10. The method for manufacturing a heater according to claim 4, characterized in that, The solder used for brazing in step S10 is a silver-based solder.

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