Component for plasma processing device, plasma processing device having the component, and method of using sintered body

Abstract

The present invention provides a component for a plasma processing device, a plasma processing device having the component, and a method for using a sintered body. The component for a plasma processing device is composed only of a tungsten carbide phase and contains at least one atom selected from the group consisting of Fe atoms, Co atoms, and Ni atoms, and the total content of these atoms is 30 to 3300 atomic ppm.

Description

Technical Field

[0001] The present disclosure relates to a component for a plasma processing device, a plasma processing device having the component, and a method of using a sintered body. Background Art

[0002] Components installed in a chamber of a plasma etching device or the like in semiconductor manufacturing are exposed to a corrosive environment formed by the plasma of an etching gas used to form a semiconductor pattern or the like. If such components are made of a material that reacts with an etchant, they may contaminate the chamber and the etched object (e.g., a semiconductor wafer), and may cause poor insulation and poor shape. In order to suppress this phenomenon, the use of silicon (Si) or quartz as components has been studied.

[0003] For example, in Patent Document 1 (Japanese Patent Publication No. 2001-135619), in order to prevent contamination caused by impurities such as heavy metals, an edge ring made of single crystal silicon is proposed. In Patent Document 2 (Japanese Patent Publication No. 62-047130), SiC, WC, TiC, etc. are proposed as materials for wafer rings. In Patent Document 3 (Japanese Patent Publication No. 2018-107433), SiC, Si, SiO2, W, WC, etc. are listed as materials for edge rings. In addition to these materials, aluminum or aluminum alloys that are cheap and easy to manufacture, aluminum treated with an acid-resistant aluminum, and components in which yttrium oxide with high corrosion resistance is thermally sprayed on a substrate such as aluminum are also known.

[0004] However, among the above materials, aluminum is not sufficiently resistant to plasma corrosion, and there is a concern that the frequency of component replacement will increase due to consumption. Although it is conceivable to provide a corrosion-resistant layer as a countermeasure, if a corrosion-resistant layer is provided, particles may be generated. In addition, metal ions such as aluminum and yttrium have an adverse effect on semiconductor circuits and may cause malfunctions and failures.

[0005] Since silicon and quartz are also easily eroded by plasma, the replacement frequency of parts increases. In addition, among ceramics, tungsten carbide (WC) is an excellent material with high strength and is not easy to generate static electricity because of its high conductivity. However, WC itself has a high melting point and is a difficult sintering material, and it is difficult to obtain a sintered body with few pores that can become a particle bag. The so-called superhard alloy obtained by adding a certain amount of metal binders such as Co and Ni to WC can reduce pores, but the metal binder components such as Co and Ni may contaminate the chamber of the plasma processing device and may become a factor in the generation of particles. This metal contamination is particularly easy to occur when the metal component is contained as a "phase". This is because the etching speed (etching rate) of the carbide phase and the metal phase to the plasma gas is different. In the case of the metal phase, the metal part is corroded preferentially, releasing a large amount of contaminated metal. Summary of the invention

[0006] Therefore, the present disclosure provides a component for a plasma processing device that has excellent corrosion resistance to plasma processing and can fully suppress metal contamination in the plasma processing device. In addition, a plasma processing device that has excellent corrosion resistance and can fully suppress metal contamination in the device is provided. In addition, the present disclosure also provides a method of using a sintered body that has excellent corrosion resistance to plasma processing and can fully suppress metal contamination in the plasma processing device as a component of a plasma processing device.

[0007] The present disclosure provides, in one aspect, a component (sintered body) for a plasma processing apparatus, which consists only of a tungsten carbide phase and contains at least one atom selected from the group consisting of Fe atoms, Co atoms, and Ni atoms, wherein the total content of these atoms is 30 to 3300 atomic ppm.

[0008] Since the above-mentioned components are composed only of the tungsten carbide phase, they have excellent corrosion resistance to plasma treatment. In addition, if multiple phases are contained, particle bags are easily generated due to the difference in etching rate, but since the components of the present invention are composed of only one phase, particle bags are not easily generated. Here, tungsten carbide itself is difficult to sinter, and the ratio of pores tends to increase, and the pores sometimes become particle bags. However, the components of the present invention contain a specified amount of at least one atom selected from the group consisting of Fe atoms, Co atoms and Ni atoms. Thereby, the sintering of tungsten carbide can be promoted to reduce porosity, and the generation of particle bags can be suppressed. In addition, there is an upper limit to the total content of Fe atoms, Co atoms and Ni atoms. Due to these factors, metal contamination in the plasma treatment device can be fully suppressed.

[0009] The present disclosure provides a plasma processing device including the above-mentioned component in another aspect. The plasma processing device includes the above-mentioned component. Therefore, it is possible to provide a plasma processing device that has excellent corrosion resistance and can sufficiently suppress contamination in the device.

[0010] The present disclosure provides, on another aspect, a method of using a sintered body as a component of a plasma processing device, wherein the sintered body is composed only of a tungsten carbide phase and contains at least one atom selected from the group consisting of Fe atoms, Co atoms, and Ni atoms, and the total content of these atoms is 30 to 3300 atomic ppm.

[0011] Since the sintered body is composed of only one phase, tungsten carbide phase, it has excellent corrosion resistance to plasma treatment. In addition, if it contains multiple phases, particle bags are easily generated due to the difference in etching rate, but since the sintered body is composed of only one phase, it is not easy to generate particle bags. Here, tungsten carbide itself is difficult to sinter, and the ratio of pores tends to increase, and the pores may become particle bags. However, the sintered body contains a specified amount of at least one atom selected from the group consisting of Fe atoms, Co atoms and Ni atoms. Thus, the sintering of tungsten carbide can be promoted to reduce porosity and inhibit the generation of particle bags. In addition, there is an upper limit to the total content of Fe atoms, Co atoms and Ni atoms. Due to these factors, metal contamination in the plasma treatment device can be fully suppressed.

[0012] According to the present disclosure, a component for a plasma processing device having excellent corrosion resistance to plasma processing and capable of sufficiently suppressing metal contamination in the plasma processing device can be provided. Furthermore, a plasma processing device having excellent corrosion resistance and capable of sufficiently suppressing contamination in the device can be provided. Furthermore, a method of use can be provided, which uses a sintered body having excellent corrosion resistance to plasma processing and capable of sufficiently suppressing metal contamination in the plasma processing device as a component of a plasma processing device. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic cross-sectional view showing one embodiment of a plasma processing apparatus. Figure 2 This is a graph showing the relationship between the pulverization time and the Co content after pulverization. Figure 3 It is a diagram showing an overview of plasma etching processing. DETAILED DESCRIPTION

[0014] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings as appropriate. However, the following embodiment is an example for describing the present disclosure, and is not intended to limit the present disclosure to the following contents.

[0015] The component for a plasma processing device involved in one embodiment of the present disclosure is composed of a sintered body and is composed only of a tungsten carbide phase. The tungsten carbide phase (WC phase) in the present disclosure refers to a crystalline phase of tungsten carbide. That is, the component of the present embodiment does not contain a crystalline phase other than the WC phase. Since the WC phase has excellent corrosion resistance to plasma etching, the life of the component can be extended. The component contains a specified amount of at least one atom selected from the group consisting of Fe atoms, Co atoms and Ni atoms. These atoms can be dissolved in the WC phase or at the grain boundaries of the crystals of the WC phase. The concentration of these atoms at the grain boundaries can be higher than the concentration in the crystals of the WC phase within the range of not forming a phase. The total content of Fe atoms, Co atoms and Ni atoms in the above-mentioned components is 30 to 3300 atomic ppm, can be 30 to 2100 atomic ppm, or can be 30 to 1650 atomic ppm.

[0016] By setting the total content of the above atoms to more than 30 atomic ppm, the sintering of tungsten carbide as a difficult-to-sinter material can be promoted and the porosity can be reduced. On the other hand, if the content of the above atoms is too much, different phases such as metal phases are formed, and this part is preferentially etched by plasma. As a result, concave and convex are generated on the surface of the component to form a particle bag. In addition, the metal phase is etched by plasma, and metal ions float, which tends to become a pollution source for etching processed objects such as semiconductor wafers.

[0017] Therefore, in the present embodiment, by setting the total content of the above atoms to 3300 atomic ppm or less, the generation of phases other than the tungsten carbide phase can be suppressed, and metal contamination in the plasma processing device can be suppressed. By setting the total content of the above atoms to 2100 atomic ppm or less, metal contamination in the plasma processing device can be fully suppressed. By setting the total content of the above atoms to 1650 atomic ppm or less, metal contamination in the plasma processing device can be further fully suppressed. The content of each atom in the component can be measured by glow discharge mass spectrometry (GDMS).

[0018] The “corrosion resistance” in the present disclosure refers to the corrosion resistance to plasma processing using a fluorocarbon-based or halogen-based etching gas.

[0019] From the viewpoint of further suppressing metal contamination inside the device, the content of each of Fe atoms, Co atoms, and Ni atoms in the component may be 1650 atomic ppm or less, 1200 atomic ppm or less, or 1000 atomic ppm or less. On the other hand, from the viewpoint of reducing the manufacturing cost of the component, the content of each of Fe atoms, Co atoms, and Ni atoms in the component may be 30 atomic ppm or more, or 300 atomic ppm or more.

[0020] The component of this embodiment may not contain metal atoms other than W atoms, Fe atoms, Co atoms, and Ni atoms. From the viewpoint of further fully suppressing metal contamination in the plasma processing device, the total amount of metal atoms other than W atoms, Fe atoms, Co atoms, and Ni atoms may be 1650 atomic ppm or less. Furthermore, the content of each metal atom other than W atoms, Fe atoms, Co atoms, and Ni atoms may be 300 atomic ppm or less.

[0021] From the perspective of reducing the particle pockets generated by plasma treatment, the porosity of the above-mentioned component may be 2% by volume or less. From the perspective of sufficiently reducing the particle pockets generated by plasma treatment and reducing manufacturing costs, the porosity may be 0.05 to 1% by volume, or 0.1 to 0.5% by volume. The porosity can be calculated by grinding a cross section of the component and observing the image of the ground surface using a scanning electron microscope.

[0022] The component of the present embodiment is composed only of a WC phase having excellent corrosion resistance to plasma treatment. Therefore, the etching rate of the component is extremely low, and a long life can be achieved, for example, compared with a component composed of silicon. In addition, compared with a plurality of phases, it is not easy to produce unevenness on the surface of the component due to the difference in etching rate. Therefore, particle bags are not easy to produce and metal contamination can be suppressed. In addition, since it contains iron group atoms (Fe atoms, Co atoms, Ni atoms) that have the effect of promoting sintering, the pores that cause particle bags in the component can be substantially reduced compared with pure tungsten carbide. By using such a component in a plasma processing device, it is possible to reduce the pollution in the etched object and the device, and it is possible to achieve quality improvement and increase the yield of products based on the semiconductor manufacturing process.

[0023] When plasma etching is performed by a plasma processing device, a material containing tungsten is sometimes used as a mask material. In this case, tungsten is used in the chamber, so the etched object is treated to remove tungsten. Therefore, the above treatment can remove contamination caused by tungsten in the component without adding a new cleaning process.

[0024] An example of a method for manufacturing a component for a plasma processing device is described below. As a raw material, tungsten carbide powder is prepared. From the perspective of fully reducing metal contamination, the purity of the tungsten carbide powder can be 99.9 mass % or more. Regarding the average particle size, from the perspective of sinterability and processability, it can be about 0.1 to 4 μm.

[0025] As a method of adding iron group metals (Fe, Ni, Co), the metals in powder state can be mixed, or they can be mixed from the medium in the mixing and stirring process described later. In addition, powders of compounds with iron group elements as constituent elements can be mixed, or the compounds can be made into aqueous solutions and mixed in the state of ions. In this way, the form of the raw materials is not particularly limited. In the case of mixing in a powder state, powders with an average particle size of about 0.5 to 5 μm can be used. As for the addition amount, considering that there will be some vaporization and scattering until the end of sintering, the total content of iron group atoms in the state of the mixed powder described later can be set to about 30 to 3500 atomic ppm.

[0026] For example, tungsten carbide powder is mixed and stirred with iron group metal powder added as needed by a known dry or wet method. Then, as needed, it is dried or an organic binder is added to obtain a molding raw material. When the iron group metal is added in the form of a powder state or an aqueous solution, it can be mixed and stirred with the tungsten carbide powder.

[0027] Next, the molding raw material is subjected to pressure molding to obtain a molded body. The pressure molding can be performed using a mold and a punch, or a wet punch using hydrostatic pressure. The maximum pressure during the punching can be performed at about 10 to 500 MPa. The obtained molded body can be degreased, pre-sintered, or intermediately processed as needed.

[0028] The formed body or the processed body after degreasing, pre-sintering and intermediate processing is placed in a sintering furnace for sintering. Sintering can be carried out in a non-oxidizing atmosphere (hydrogen atmosphere, ammonia atmosphere, vacuum atmosphere containing carbon or rare gas atmosphere, etc.). Since tungsten carbide is a difficult-to-sinter material, the maximum temperature during sintering can be around 1800-2400°C.

[0029] After sintering, the sintered body can be subjected to HIP (hot isostatic pressing) treatment to further reduce residual pores. In addition, in the case of applications and shapes requiring dimensional accuracy, the sintered body can be subjected to various well-known surface treatments such as mechanical processing and electrical processing. In this way, a component for a plasma processing device composed of a sintered body can be obtained. The manufacturing method of the component is not limited to the above example, and hot pressing or SPS (spark plasma sintering) can be used according to the shape.

[0030] Tungsten carbide sometimes reacts locally at high temperatures during sintering. Therefore, the composition ratio in the molding raw material can be inconsistent with the composition ratio in the component. This is due to the following reasons: tungsten carbide is not an ideal compound with a W1C1 ratio (relative to the stoichiometric ratio of W of 1, the stoichiometric ratio of C is less than 1); and carbon is exchanged with the atmosphere during firing (including firing jigs, etc.); carbon exchange occurs between tungsten carbide and carbon sources other than tungsten carbide, etc.

[0031] The ratio of the raw materials put in and the sintering conditions can be adjusted so that the sintered body is composed of only the tungsten carbide phase. The sintered body obtained in this way has sufficient corrosion resistance for plasma treatment, so when plasma treatment is performed, the generation of particle bags and metal contamination can be fully suppressed. Therefore, it can be suitable for use as a component for a plasma treatment device used in a semiconductor manufacturing process. As specific components, an edge ring arranged around a semiconductor wafer, an electrostatic suction cup for adsorbing semiconductors, a wafer mounting substrate, a shower plate as an etching processing gas supply unit, a core column of a water jacket as a structure for flowing cooling water, and a chamber inner wall material can be cited.

[0032] Figure 1 1 is a longitudinal sectional view showing an example of a plasma processing device 10 according to an embodiment. The plasma processing device 10 of the present embodiment is a capacitively coupled plasma (CCP) parallel plate plasma processing device. In the plasma processing device 10, a gas is converted into plasma in a chamber 11, and a wafer Wa placed on a mounting table 20 is processed by the action of plasma. The wafer Wa is, for example, a semiconductor wafer. The plasma processing device 10 is an example of a processing device.

[0033] The plasma processing apparatus 10 includes a substantially cylindrical chamber 11. The inner surface of the chamber 11 is subjected to anodizing treatment. The chamber 11 is divided into a processing chamber U for performing plasma etching treatment and film forming treatment on a wafer Wa.

[0034] The mounting table 20 includes the susceptor 18 and the electrostatic chuck 21, and mounts the wafer Wa. The mounting table 20 also functions as a lower electrode.

[0035] An electrostatic chuck 21 is provided on the susceptor 18. The electrostatic chuck 21 is formed into a structure in which a chuck electrode 21a is sandwiched between insulators 21b. A DC power source 22 is connected to the chuck electrode 21a via a switch 23. When the switch 23 is turned on, a DC voltage is applied from the DC power source 22 to the chuck electrode 21a. As a result, the wafer Wa is attracted to the electrostatic chuck 21 by the Coulomb force.

[0036] An annular edge ring 87 is placed around the wafer Wa and on the outer peripheral placement surface of the electrostatic chuck 21. The edge ring 87 is also called a focusing ring and has the function of converging the plasma in the processing chamber U toward the surface of the wafer Wa to improve the efficiency of plasma processing.

[0037] The mounting table 20 is held at the bottom of the chamber 11 by the support 14. A refrigerant flow path 24 is formed inside the base 18. The cooling medium such as cooling water and brine output from the refrigerator unit flows through the refrigerant inlet pipe 26a, the refrigerant flow path 24, and the refrigerant outlet pipe 26b, returns to the refrigerator unit, is controlled to a predetermined temperature, and circulates in the above path. In this way, the mounting table 20 is cooled by removing heat.

[0038] A heat transfer gas such as helium (He) supplied from a heat transfer gas supply source is supplied between the mounting surface of the electrostatic chuck 21 and the back side of the wafer Wa through the gas supply line 28. The wafer Wa is controlled to a predetermined temperature by the cooling medium circulating in the refrigerant flow path 24 and the heat transfer gas supplied to the back side of the wafer Wa.

[0039] The first high-frequency power source 32 is electrically connected to the mounting table 20 via the first matching device 33, and applies a high-frequency power HF (e.g., 40 MHz) for plasma generation of a first frequency to the mounting table 20. Furthermore, the second high-frequency power source 34 is electrically connected to the mounting table 20 via the second matching device 35, and applies a high-frequency power LF (e.g., 13.56 MHz) for bias voltage generation of a second frequency lower than the first frequency to the mounting table 20.

[0040] The first matching device 33 matches the load impedance on the plasma side with the internal impedance of the first high-frequency power source 32. The second matching device 35 matches the load impedance on the plasma side with the internal impedance of the second high-frequency power source 34.

[0041] The gas shower head 25 is installed to close the opening of the top of the chamber 11 via a cylindrical shield ring 40 provided on the outer edge thereof. The gas shower head 25 also functions as a counter electrode (upper electrode) facing the mounting table 20 (lower electrode). A top shield ring 41 is arranged on the lower surface of the shield ring 40 at the periphery of the gas shower head 25.

[0042] The gas shower head 25 has a gas inlet 45 for introducing gas. A diffusion chamber 46 is provided inside the gas shower head 25. The gas output from the gas supply source 15 is supplied to the diffusion chamber 46 through the gas inlet 45, diffused in the diffusion chamber 46, and introduced into the processing chamber U in the chamber 11 through a plurality of gas supply holes 47.

[0043] An exhaust port 55 is formed on the bottom surface of the chamber 11, and the inside of the chamber 11 is exhausted by an exhaust device 50 connected to the exhaust port 55. Thus, a predetermined vacuum level can be maintained in the chamber 11. A gate valve G is provided on the side wall of the chamber 11, and by opening and closing the gate valve G, the wafer Wa is transferred from the transfer port to the inside of the chamber 11 or outside of the chamber 11.

[0044] A cylindrical insulating ring 86 is disposed so as to cover the outer peripheral side surface of the mounting table 20 . Furthermore, a cylindrical shielding ring 89 is disposed so as to cover the outer peripheral side surface of the edge ring 87 .

[0045] A deposition guard 82 is provided along the inner wall surface of the side of the chamber 11. In addition, a deposition guard 83 is provided along the outer peripheral side surface of the mounting table 20 and the support body 14. The deposition guards 82 and 83 are configured to be freely detachable. The deposition guards 82 and 83 prevent byproducts (deposits) generated by the plasma etching process performed in the chamber 11 from adhering to the inner wall of the chamber 11.

[0046] An annular baffle plate 81 is provided in the annular exhaust passage between the deposition guards 82 and 83. An exhaust port 55 is provided in the exhaust passage 49 below the baffle plate 81.

[0047] The plasma processing device 10 is provided with a control unit 100 for controlling the operation of the entire device. The control unit 100 includes a CPU (Central Processing Unit) 105, a ROM (Read Only Memory) 110, and a RAM (Random Access Memory) 115. The CPU 105 performs a desired plasma process such as etching according to a recipe stored in a storage area such as the RAM 115. The recipe sets control information of the device for process conditions, namely, process time, pressure (gas exhaust), high frequency power or voltage, various gas flow rates, chamber temperature, temperature of a cooling medium, and the like.

[0048] When plasma processing is performed, the gate valve G is opened and closed, and the wafer Wa is carried into the chamber 11 and placed on the mounting table 20. When a DC voltage is applied from the DC power supply 22 to the chuck electrode 21a, the wafer Wa is attracted to the electrostatic chuck 21 and held.

[0049] The processing gas is supplied from the gas supply source 15 into the chamber 11. The high frequency power HF is applied to the mounting table 20 from the first high frequency power source 32, and the high frequency power LF is applied to the mounting table 20 from the second high frequency power source 34. Thus, plasma is generated in the processing chamber U, and the wafer Wa is subjected to plasma processing by the action of the plasma.

[0050] After the plasma treatment, a DC voltage opposite to that when the wafer Wa is sucked is applied from the DC power supply 22 to the chuck electrode 21a to remove the charge of the wafer Wa. Thus, the wafer Wa is peeled off the electrostatic chuck 21 and carried out of the chamber 11 through the gate valve G.

[0051] In the plasma processing apparatus 10, the components involved in the above-mentioned embodiment may also be used to constitute the components exposed to the plasma processing. For example, at least one selected from the group consisting of the edge ring 87, the shielding ring 89, the baffle 81, the gas shower head 25, the top shield ring 41, the deposition guard 82, and the deposition guard 83 may be constituted by the above-mentioned components (sintered bodies). The plasma processing apparatus is not limited to Figure 1 The above-mentioned components can be used in various semiconductor manufacturing devices for plasma processing. The components to which the above-mentioned components are applied are not particularly limited. For example, they can also be applied to shower plates, susceptors, and the inner wall of a processing container. By using the above-mentioned sintered body in a plasma processing device, the corrosion resistance of the components of the plasma processing device 10 can be improved, and metal contamination in the etched objects such as wafers Wa and the device can be fully suppressed.

[0052] The above embodiment can also be referred to as a method of using the above sintered body as a component of a plasma processing apparatus. As mentioned above, one embodiment of the present disclosure has been described, but the present disclosure is not limited to the above embodiment.

[0053] Example

[0054] The present invention will be described in further detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[0055] (Examples 1 to 14)

[0056] [Preparation of raw materials]

[0057] Commercially available WC powder (average particle size: 0.6 μm, Co content: 150 atomic ppm) was prepared. 5000 g of WC powder and 1800 ml of methanol were placed in a 5 L binder-free superhard lined pot and pulverized using a ball mill (rotation speed: 64 rpm), and the relationship between pulverization time (0 to 50 hours) and Co content was analyzed. As the material of the ball, a material made of superhard alloy without a binder and a material made of superhard alloy containing a binder (Co, 13 mass%) were used, and the amount of binder component mixed in the WC powder due to the difference in the material of the ball was analyzed.

[0058] Figure 2 It is a graph showing the relationship between the pulverization time and the Co content after pulverization. Figure 2As shown, by using a super-hard alloy ball containing a binder for pulverization, it was confirmed that the content of Co atoms increased. By this preparation method, a variety of raw materials with different contents of Co atoms were prepared. Similarly, a variety of raw materials with different contents of Ni atoms and Fe atoms were prepared. The raw material of Example 1 was prepared by mixing WC powder that almost did not contain Co as an impurity in a short time without using a super-hard alloy ball.

[0059] [Production of sintered body]

[0060] A variety of molding raw materials with different iron group metal contents were prepared using the raw materials obtained by the above-mentioned "preparation of raw materials". The prepared molding raw materials were placed in a mold of a specified size and pressurized at 100 MPa using a punch. In this way, a plurality of molded bodies with different metal contents were produced. Each molded body was sintered at 2200°C for 2 hours under vacuum. Then, HIP treatment was performed under the conditions of 1700°C and 200 MPa to obtain a sintered body of each embodiment. A sintered body containing two or more atoms of Co atoms, Ni atoms and Fe atoms is produced using a molding raw material obtained by mixing two or more raw materials.

[0061] The content of iron group atoms and porosity in the sintered bodies of each embodiment are summarized and shown in Table 1. The results of X-ray diffraction and EDX mapping confirmed that the sintered bodies of each embodiment consisted of only tungsten carbide phase. The content of iron group atoms was analyzed by glow discharge mass spectrometry (GDMS). The porosity was obtained by grinding the cross section of the sintered body and performing image analysis on the ground surface.

[0062] [Table 1]

[0063]

[0064] <Evaluation of strength>

[0065] The sintered bodies of Examples 1 to 14 all have electrical conductivity, and the mechanical strength (three-point bending strength) is in the range of 700 to 1800 MPa.

[0066] (Comparative Examples 1 to 9)

[0067] Commercially available powders were used to prepare samples (sintered bodies) having the compositions shown in Table 2. Comparative Example 1 is a silicon component used as various components in a processing container of a plasma processing device. Silicon components are easily etched by plasma.

[0068] The aluminum oxide of Comparative Example 2 is more difficult to etch than silicon. However, the corrosion resistance to etching is not sufficient. Comparative Example 3 is a component of tungsten carbide (Co atom content: 15 atomic ppm). The raw material of this sintered body is prepared by selecting a powder with a low Co content as WC powder and not mixing iron group elements during mixing. Tungsten carbide monomer is a difficult-to-sinter material. The result of making a sintered body under the same conditions as the embodiment is that the relative density is 95.6% (porosity is 4.4 volume %).

[0069] Comparative Example 4 is a superhard alloy classified as a low-cobalt superhard alloy and having a low Co content. Comparative Example 5 is a conventional superhard alloy containing Co as a binder. The sintered body was prepared in the same order as Examples 1 to 14, except that Co (20.7% by volume) was added as a binder to commercially available tungsten carbide powder and the sintering temperature was set to 1450°C. The relative density of the sintered body of Comparative Example 5 is almost 100%. Comparative Example 6 is a conventional superhard alloy containing Ni as a binder. Comparative Example 7 is a superhard alloy obtained by adding carbides having elements of Groups 4 to 6 of the periodic table as constituent elements to a superhard alloy containing Co as a binder.

[0070] Comparative Example 8 is a sintered body containing carbides with elements of Groups 4 to 6 of the periodic table as constituent elements in tungsten carbide. The raw material of the sintered body is prepared by selecting a powder with a small Co content as WC powder and adding the above-mentioned tungsten carbide in a manner that does not mix iron group elements during mixing. In Comparative Example 8, phases other than tungsten carbide phases are generated. Comparative Example 9 is a test piece in which a thermal spray film of Y2O3 is applied on an aluminum substrate.

[0071] [Table 2]

[0072]

[0073] [Evaluation 1 as a component for a plasma processing apparatus]

[0074] <Plasma Etching Process>

[0075] The plasma etching of the sintered bodies (components) of each embodiment and each comparative example was evaluated in the following order. The sintered bodies were machined to produce evaluation samples with a size of φ30 mm×3 mm. The surfaces of the evaluation samples were mirror-finished. Then, as Figure 3 As shown, a part of the mirror-finished surface of the sintered body 1 was masked with a masking tape 3 made of a polyimide tape, and a plasma etching process was performed using a plasma processing device.

[0076] As a plasma processing device, a parallel plate type reactive ion plasma etching device for mass production of 8-inch LSI was used. The etching conditions based on CF4 gas plasma were cathode temperature 60°C, anode temperature 30°C, RF power output 1000W, chamber gas pressure 16Pa, etching time 60 minutes, and gas flow rate 60sccm. Through plasma etching treatment, Figure 3 As shown, the unmasked portion of the surface of the sintered body is etched.

[0077] <Etching depth D>

[0078] After the plasma etching treatment, the masking tape 3 was peeled off from the surface, and the step difference between the non-etched surface and the etched surface was measured using a profile measuring instrument (trade name: Surfcom2800, manufactured by TOKYO SEIMITSU CO., LTD.) to determine the etching depth D.

[0079] The etching depths D of Comparative Examples 1 and 2 were 34 μm and 3.6 μm, respectively. In contrast, the etching depths D of Examples 1 to 14 and Comparative Examples 3, 4, 8, and 9 were all within 1.5 μm. It was confirmed that Examples 1 to 14 had better corrosion resistance than Comparative Examples 1 and 2.

[0080] <Number of particles>

[0081] The number of particles after the plasma etching process was measured using a commercially available particle counter in accordance with JIS B 9921. The number of particles measured in Comparative Example 1 was approximately 100. In contrast, Examples 1 to 14 and Comparative Example 8 were in the range of 20 to 100. Comparative Examples 3 to 7 had more than 100 particles.

[0082] Regarding Comparative Example 3, it is believed that due to the high porosity, the pores on the surface become particle pockets, making it easy to hold the particles. Regarding Comparative Examples 4 to 7, they contain metal phases (Co phases or Ni phases) with a size of several μm or more. These metal phases have lower corrosion resistance than tungsten carbide phases. Therefore, it is believed that during the plasma etching process, grooves (step differences caused by corrosion) are generated between the tungsten carbide phase and the tungsten carbide phase, which become particle pockets, making it easy to hold the particles. Regarding Comparative Example 9, due to the thermal expansion difference caused by temperature changes, fine peeling occurred on a portion of the surface.

[0083] <Metal contamination>

[0084] The plasma-etched sintered body was cleaned with a cleaning solution (hydrofluoric acid). The cleaning solution was analyzed by ICP-MS (inductively coupled plasma mass spectrometry) to evaluate metal contamination. The elements analyzed were 13 elements: Na, Mg, Al, K, Ca, Ti, Cr, Fe, Co, Ni, Cu, Zn, and W.

[0085] In the semiconductor manufacturing process, Cu, Ti, and Ca, which are harmful metal elements that are particularly prone to contaminating circuits, will be greater than 3×10 10 (atoms / cm 2 ) are judged as unqualified. For metal elements other than Cu, Ti, Ca and W, for those with more than 20×10 10 (atoms / cm 2 ) was judged as unqualified. As for W, it is the same as the metal mask component and is removed by the process in the subsequent steps, so the impact is small and it is excluded from the evaluation of metal contamination.

[0086] Based on the above criteria, Examples 1 to 14 and Comparative Examples 1, 2, 3, and 9 were evaluated as acceptable. Comparative Examples 4, 5, 6, and 7 were evaluated as unacceptable because large amounts of Co or Ni were detected. Comparative Example 8 was evaluated as unacceptable because large amounts of Ti were detected.

[0087] To summarize the above results, in Examples 1 to 14, the etching depth D was small enough, and the number of observed particles was equal to or less than that of Comparative Example 1. In addition, the metal contamination was below the allowable value. In addition, all samples had conductivity, and no peeling occurred in any evaluation. On the other hand, in Comparative Example 1, although there was no problem with conductivity, there was difficulty in processing into the desired shape due to low strength. In addition, the etching depth D was the largest, and the corrosion resistance was insufficient.

[0088] In Comparative Example 2, the etching depth D is improved compared to Comparative Example 1. However, the etching depth D is larger than that of Examples 1 to 14. Furthermore, since it has no conductivity, it tends to easily attract particles due to electrostatic discharge.

[0089] In Comparative Example 3, even with washing, the number of particles could not be sufficiently reduced. This is considered to be the result of a large number of pores existing on the surface and inside becoming particle pockets.

[0090] Comparative Examples 4, 5, and 6 have metal phases such as Co and Ni. The metal phase is etched first to produce unevenness, which is considered to be the cause of the formation of particle pockets. In addition, the amount of Co and Ni in the metal contamination greatly exceeds the allowable range. The same is true for Comparative Example 7. In Comparative Example 8, since the volume ratio of TiC and TaC is high, it is detected that Ti and Ta exceed the allowable amount.

[0091] [Evaluation 2 as a component for plasma processing apparatus]

[0092] <Measurement of particle count and evaluation of metal contamination>

[0093] The sintered bodies of Example 3, Comparative Example 1 and Comparative Example 8 were prepared as follows. Figure 1Components of the plasma processing device shown (etching). Then, the silicon wafer was etched under the same etching conditions as in the above-mentioned "Evaluation 1". The silicon wafer after the plasma etching was cleaned using a cleaning liquid (hydrofluoric acid). The cleaning liquid was analyzed in the same manner as in the above-mentioned "Metal Contamination", and the metal contamination was evaluated. The evaluation results of the metal contamination are shown in Table 3.

[0094] [Table 3]

[0095] Example 3 Comparative Example 1 Comparative Example 8 Na 40 20 ＜7.4 Mg 0.08 0.43 ＜7.0 Al 5.4 4 ＜6.3 K 3.5 12 ＜4.4 Ca 2.5 1.8 9.7 Ti 1.3 2.8 11000 Cr 3.5 0.22 53 Fe 1.9 0.59 39 Co 3.3 - 64 Ni 0.3 0.069 4.8 Cu 0.8 3.1 4.4 Zn 0.1 1.7 ＜2.6 W 5500 0.046 10000

[0096] The unit of the values ​​in the table is [×10 10 atoms / cm 2 ].

[0097] In Table 3, when the sintered body of Example 3 is used as a component, the allowable values ​​are satisfied in all elements. The W content is high, but this is a component that can be removed by washing, so there is no particular problem. On the other hand, in Comparative Example 8, the Ti content is high.

Claims

1. A component for a plasma processing device, which is a sintered body whose crystal phase consists only of a tungsten carbide phase, The sintered body includes at least one atom selected from the group consisting of Fe atoms, Co atoms, and Ni atoms, The total content of these atoms in the sintered body is 30 to 3300 atomic ppm. The total amount of metal atoms other than W atoms, Fe atoms, Co atoms, and Ni atoms in the sintered body is 1650 atomic ppm or less.

2. The component according to claim 1, wherein The porosity of the sintered body is 2 volume % or less.

3. A component according to claim 1 or 2, wherein: The content of each of Fe atoms, Co atoms and Ni atoms in the sintered body is 1650 atomic ppm or less.

4. A plasma processing device comprising a component composed of a sintered body, wherein: The crystalline phase of the sintered body is composed only of tungsten carbide phase, The sintered body includes at least one atom selected from the group consisting of Fe atoms, Co atoms, and Ni atoms, The total content of these atoms in the sintered body is 30 to 3300 atomic ppm.

5. A method of using a sintered body as a component of a plasma processing device, wherein: The crystalline phase of the sintered body is composed of only a tungsten carbide phase and contains at least one atom selected from the group consisting of Fe atoms, Co atoms, and Ni atoms. The total content of these atoms is 30 to 3300 atomic ppm. The total amount of metal atoms other than W atoms, Fe atoms, Co atoms, and Ni atoms in the sintered body is 1650 atomic ppm or less.

6. The method of use according to claim 5, wherein: The porosity of the sintered body is 2 volume % or less.

7. The method of use according to claim 5 or 6, wherein: The content of each of Fe atoms, Co atoms and Ni atoms in the sintered body is 1650 atomic ppm or less.

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