Electrostatic chuck member and electrostatic chuck device

Abstract

This electrostatic chuck member comprises an electrostatic attraction electrode, and a plate-form dielectric substrate that surrounds the electrostatic attraction electrode and has a placement surface on which a plate-form material is placed. The dielectric substrate has a protective film on at least part of the obverse surface of the dielectric substrate. The protective film is formed of at least one type of ceramic selected from the group consisting of oxides, fluorides, and acid fluorides as a material. The material includes at least one selected from the group consisting of rare earth elements, Mg, Ca, Al, Si, and Zr. The thickness of the protective film is 0.01-10 μm.

Description

Electrostatic chuck member and electrostatic chuck device

[0001] The present application claims priority to Japanese Patent Application No. 2024-111096 filed on July 10, 2024, and Japanese Patent Application No. 2025-093645 filed on June 4, 2025, the contents of which are incorporated herein by reference.

[0002] Conventionally, manufacturing lines for semiconductor devices such as ICs, LSIs, and VLSIs include processes that use corrosive halogen-based gases such as fluorine-based gases and chlorine-based gases, or plasmas of these gases. In such processes, for example, after a semiconductor wafer is fixed by an electrostatic chuck device, the wafer may be etched or cleaned (plasma cleaning) using the halogen-based gas or plasma.

[0003] An electrostatic chuck device includes a base body having a main surface serving as a mounting surface on which a wafer is placed, and an electrostatic attraction electrode that generates an electrostatic force (Coulomb force) between the base body and the wafer placed on the mounting surface. The base body is typically made of a ceramic sintered body (dielectric substrate). However, the above-mentioned halogen-based gases and plasmas are known to be highly corrosive to the ceramic members that make up the electrostatic chuck device. Therefore, in processes using the above-mentioned halogen-based gases and plasmas, the electrostatic chuck members are easily worn by the halogen-based gases and plasmas.

[0004] To address the above-described problems, a technology has been disclosed in which an yttrium-based fluoride spray coating is provided as a corrosion-resistant coating on an electrostatic chuck member (see, for example, Patent Document 1). By forming such a spray coating on, for example, the mounting surface of the electrostatic chuck member on which a wafer is mounted, it is expected that the plasma resistance of the mounting surface will be improved. In the following description, plasma resistance may be referred to as "corrosion resistance."

[0005] JP 2017-190475 A

[0006] However, the thermal sprayed film described in Patent Document 1 is prone to pores and cracks, making it difficult to ensure corrosion resistance. Therefore, in order to obtain a thermal sprayed film with sufficient corrosion resistance, it is considered to form the thermal sprayed film thick. When a thick thermal sprayed film is formed on the mounting surface of the electrostatic chuck member, the corrosion resistance of the mounting surface is easily achieved.

[0007] On the other hand, if a thick thermal sprayed film is formed on the mounting surface, the distance between the electrostatic attraction electrode of the electrostatic chuck member and the wafer placed on the mounting surface increases, which raises concerns about a decrease in the Coulomb force that attracts the wafer. A decrease in the attracting force (Coulomb force) of the electrostatic chuck member may affect the processing state of the wafer and may reduce the yield of wafer processing.

[0008] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a novel electrostatic chuck member having improved corrosion resistance, and a further object of the present invention is to provide a novel electrostatic chuck device having such an electrostatic chuck member and having improved corrosion resistance.

[0009] In order to solve the above problems, one aspect of the present invention includes the following aspects.

[0010] [1] An electrostatic chuck member comprising: an electrostatic attraction electrode; and a plate-shaped dielectric substrate containing the electrostatic attraction electrode and having a mounting surface on which a plate-shaped sample is placed, the dielectric substrate having a protective film on at least a portion of a surface of the dielectric substrate, the protective film being formed from at least one ceramic material selected from the group consisting of oxides, fluorides, and oxyfluorides, the material including at least one selected from the group consisting of rare earth elements, Mg, Ca, Al, Si, and Zr, and the protective film having a thickness of 0.01 μm or more and 10 μm or less.

[0011] [2] The electrostatic chuck member according to [1], wherein the protective film is provided on the peripheral edge of the dielectric substrate on the mounting surface side.

[0012] [3] The electrostatic chuck member according to [2], wherein the protective film is provided on the entire surface of the mounting surface side of the dielectric substrate.

[0013] [4] The electrostatic chuck member according to any one of [1] to [3], wherein the protective film is provided on a side surface of the dielectric substrate.

[0014] [5] The volume resistivity of the protective film is 1.0 × 10 ８ Ω・cm or more 1.0×10 ２０ [4] The electrostatic chuck member according to any one of [1] to [3], wherein the electrostatic chuck member has a resistivity of Ω·cm or less.

[0015] [6] An electrostatic chuck device comprising: the electrostatic chuck member according to any one of [1] to [5]; and a base supporting the electrostatic chuck member from the one surface side.

[0016] [7] The electrostatic chuck device according to [6], further comprising a bonding layer that bonds the electrostatic chuck member and the base.

[0017] [8] The electrostatic chuck device according to [6] or [7], wherein the base is made of a conductive ceramic, the conductive ceramic being composed of a highly thermally conductive material and a conductive material, and the volume ratio of the highly thermally conductive material to the conductive material is 10:90 to 90:10.

[0018] According to the present invention, it is possible to provide a novel electrostatic chuck member having improved corrosion resistance, and also to provide a novel electrostatic chuck device having such an electrostatic chuck member and having improved corrosion resistance.

[0019] Fig. 1 is a schematic cross-sectional view showing an example of an electrostatic chuck member 10 according to this embodiment. Fig. 2 is a schematic cross-sectional view of an electrostatic chuck member 10B according to a modified example of this embodiment. Fig. 3 is a schematic cross-sectional view showing an example of an electrostatic chuck device 1 according to this embodiment.

[0020] <Electrostatic Chuck Member> A preferred example of an electrostatic chuck member according to this embodiment will be described below with reference to Figures 1 and 2. In all of the following drawings, the dimensions and ratios of the components have been appropriately changed to make the drawings easier to understand. The following description is provided for specific purposes to facilitate a better understanding of the spirit of the invention, and does not limit the present invention unless otherwise specified. For example, unless otherwise specified, conditions such as shape, size, number, material, quantity, type, position, and ratio may be changed, added, or omitted as necessary.

[0021] 1 is a schematic cross-sectional view showing a preferred example of an electrostatic chuck member 10 according to this embodiment. The electrostatic chuck member 10 includes a dielectric substrate 11 and an electrostatic attraction electrode 13 contained within the dielectric substrate 11. In the following description, the electrostatic attraction electrode will be simply referred to as the "electrode."

[0022] One surface of the electrostatic chuck member 10 is a mounting surface 10x on which a plate-shaped sample is placed. A circular protrusion having a square cross section may be provided around the peripheral edge of the mounting surface 10x to prevent leakage of a cooling gas such as helium (He). This circular protrusion has, for example, a doughnut shape (closed ring shape) in plan view.

[0023] The mounting surface 10x may have a plurality of minute protrusions on its surface. In an electrostatic chuck member having minute protrusions on the mounting surface 10x, a virtual plane in contact with the tops of the minute protrusions is defined as the mounting surface 10x. When the virtual surface thus defined is a concave or convex surface, the mean square plane of the virtual surface is defined as the mounting surface 10x.

[0024] Furthermore, the electrostatic chuck member 10 has a protective film 19 on at least a part of the surface of the dielectric substrate 11. In Fig. 1, the mounting surface 10x is shown as being covered with the protective film 19. Each of these components will be described below in order.

[0025] (Dielectric Substrate) The dielectric substrate 11 is preferably made of ceramics that has sufficient mechanical strength and is resistant to corrosive gases and their plasma.

[0026] The ceramics constituting the dielectric substrate 11 are mainly composed of aluminum oxide (Al ２ O ３ "Main component" means that it occupies 50% or more by volume of the whole. ２ O ３ may account for 60% by volume or more, 70% by volume or more, 80% by volume or more, 90% by volume or more, or 98% by volume or more of the total. ２ O ３ Sintered body, Al ２ O ３ In particular, from the viewpoints of dielectric properties at high temperatures, high corrosion resistance, plasma resistance, and heat resistance, the material constituting the dielectric substrate 11 is preferably Al. ２ O ３ A sintered SiC composite is preferred.

[0027] The dielectric substrate 11 has a circular or substantially circular plate shape in a plan view. The dielectric substrate 11 may have, for example, a plurality of protrusions (convex portions, not shown) formed at predetermined intervals on the surface of the mounting surface 10x side. In this case, the tips of the plurality of protrusions form the mounting surface that supports the wafer W. In this specification, the term "plan view" refers to a field of view seen from the thickness direction (stacking direction) of the electrostatic chuck member 10.

[0028] (Electrode for Electrostatic Adsorption) The electrode 13 is disposed inside the dielectric substrate 11. The electrode 13 preferably extends in a plate shape along the mounting surface 10x of the dielectric substrate 11. When a voltage is applied to the electrode 13, it generates an electrostatic adsorption force that holds a wafer (not shown) on the mounting surface 10x.

[0029] A power supply terminal (not shown) for applying a DC voltage to the electrode 13 is connected to the electrode 13 .

[0030] The electrode 13 may be formed from any material that is electrically conductive. The electrode 13 is preferably formed from, for example, a composite of an insulating material and a conductive material. The ratio of the insulating material to the conductive material can be selected as needed. The insulating material contained in the electrode 13 is not particularly limited, but may be, for example, Al ２ O ３, aluminum nitride (AlN), silicon nitride (Si ３ N ４ ), yttrium (III) oxide (Y ２ O ３ ), yttrium aluminum garnet (YAG) and SmAlO ３ It is preferable that the polymer is at least one selected from the group consisting of:

[0031] The conductive material contained in the electrode 13 is molybdenum carbide (Mo ２ It is preferable that the material is at least one selected from the group consisting of silicon carbide (SiC), molybdenum (Mo), tungsten carbide (WC), tungsten (W), tantalum carbide (TaC), tantalum (Ta), SiC, carbon black, carbon nanotubes, and carbon nanofibers.

[0032] (Protective Film) The protective film 19 is made of ceramics with excellent plasma resistance. Specifically, the material of the protective film 19 can be at least one ceramic selected from the group consisting of oxides, fluorides, and oxyfluorides. The material of the protective film 19 also contains at least one metal selected from the group consisting of rare earth elements, Mg, Ca, Al, Si, and Zr. It is also preferable that the protective film 19 be made solely of ceramics with excellent plasma resistance that contain the rare earth elements and / or the metals.

[0033] Examples of rare earth elements include scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). From the viewpoints of availability and corrosion resistance improvement, one or more elements selected from the group consisting of Y, La, Pr, Nd, Eu, Gd, Tb, Dy, Ho, Er, and Tm are preferred. Among these, from the viewpoints of dielectric constant, volume resistivity, and dielectric loss, Y, Nd, Gd, Ho, Er, Yb, and Lu are preferred, and Y is particularly preferred.

[0034] Examples of the ceramics include the following: ２ O ３ , YAG (Y ３ Al ５ O １２ ), YAM (Y ４ Al ２ O ９ ), YAP(YAlO ３ ), yttrium silicate (Y ２ SiO ５ , Y ２ Si ２ O ７ ), yttrium borate (YBO ３ ), yttria-stabilized zirconia (YSZ), lanthanum oxide (La ２ O ３ ), lanthanum borate (LaBO ３ ), cerium oxide (CeO ２ ), neodymium oxide (Nd ２ O ３ ), neodymium aluminum oxide (Nd ３ Al ５ O １２ , Nd ４ Al ２ O9, NdAlO ３ ), samarium oxide (Sm ２ O ３ ), gadolinium oxide (Gd ２ O ３ ), gadolinium aluminum oxide (Gd ３ Al ５ O １２ , Gd ４ Al ２ O ９ , GdAlO ３ ), holmium oxide (Ho ２ O ３ ), erbium oxide (Er ２ O ３ ), erbium aluminum oxide (Er ３ Al ５ O １２ , Er ４ Al ２ O ９ , ErAlO ３ ), ytterbium oxide (Yb ２ O３ ), lutetium oxide (Lu ２ O ３ ), magnesium oxide (MgO), magnesium aluminate (MgAl ２ O ４ ), Al ２ O ３ , silicon oxide (SiO ２ ), zirconium oxide (ZrO ２ ), CaO—ZrO ２ , CaO—Al ２ O ３ , and calcium titanium oxide (CaTiO ３ At least one selected from the group consisting of

[0035] Also, for example, YAG (Y ３ Al ５ O １２ ) Y may be partially substituted with a rare earth element other than Y, such as Gd.

[0036] Examples of fluorides include yttrium fluoride (YF ３ ), lanthanum fluoride (LaF ３ ), magnesium fluoride (MgF ２ ), and calcium fluoride (CaF ２ In addition, a part of the rare earth element may be substituted with another rare earth element.

[0037] As the oxyfluoride, for example, yttrium oxyfluoride can be used. Yttrium oxyfluoride is represented by the general formula Y ｘ O ｙ F ｚ However, for convenience, it may be abbreviated as YOF in this specification. In addition, it may be a material in which a part of Y is substituted with a rare earth element other than Y. A material in which a part of yttrium is substituted with another rare earth element is represented by the general formula Y ｘ M ｎ O ｙ F ｘwhere M is a rare earth element other than Y. In the above formula, x, y, and z can be selected as needed, but for example, x may be 1 to 17, y may be 1 to 14, and z may be 1 to 23. For example, x may be larger than y, and z may be larger than x.

[0038] In the yttrium oxyfluoride constituting the protective film 19, the ratio of oxygen atoms to fluorine atoms (oxygen atoms / fluorine atoms) is preferably 1.5 or less. The content (atomic %) of rare earth elements in the protective film 19 may be, for example, 15 atomic % to 35 atomic % or less, 20 atomic % to 32 atomic % or less, or 25 atomic % to 28 atomic % or less. O may be 5 atomic % to 60 atomic % or less, 12 atomic % to 50 atomic % or less, or 20 atomic % to 40 atomic % or less. F may be 20 atomic % to 70 atomic % or less, 30 atomic % to 60 atomic % or less, or 40 atomic % to 50 atomic % or less.

[0039] The ratio of elements constituting YOF (yttrium oxyfluoride) can be selected arbitrarily as needed. For example, Y ５ O ４ F ７ and Y ７ O ６ F ９ and Y １ O ｍ F ( ３－２ｍ ) m may be greater than 0 and about 1.5, or may be 1.5 or less. For example, m may be 0.1 or more and 1.3 or less, 0.3 or more and 1.0 or less, or 0.5 or more and 0.7 or less. YOF may consist of one type or two or more types. YOF may consist of Y １ O １ F １ Ya Y ６ O ５ F ９ may be.

[0040] Among these, YOF or yttrium oxyfluoride in which part of the yttrium is substituted with the above-mentioned other rare earth elements is preferred from the viewpoint of plasma resistance.

[0041] YOF has high plasma resistance and can therefore suitably protect from plasma the portion of the electrostatic chuck member 10 where the protective film 19 is formed. The protective film 19 is formed directly on the surface of the dielectric substrate 11 without having a configuration interposed between the protective film 19 and the dielectric substrate 11.

[0042] The thickness of the protective film 19 can be selected arbitrarily, for example, from 0.01 μm to 10 μm. For example, it may be from 0.05 μm to 8 μm, from 0.1 μm to 6 μm, or from 1 μm to 3 μm. Such a protective film 19 can be formed on the surface 11 a of the dielectric substrate 11 by sputtering, specifically, by radio-frequency magnetron sputtering, using the above-mentioned material, such as YOF, as a target material. Radio-frequency (RF) magnetron sputtering, as will be described later, may refer to, for example, a method using a radio-frequency power source (alternating-current power source) to collide positive ions (gas ion atoms such as Ar) with an insulating target having a magnet attached on the backside, scattering particles of the target and depositing them on an object.

[0043] The target material used can be selected arbitrarily as needed, and may be a sintered body formed using the above-mentioned material such as YOF, or may be an unsintered powdered material, or a molded body formed by solidifying the powdered material.

[0044] The target material may also be a sprayed film formed from the above material. The sprayed film may refer to, for example, a coating film obtained by melting the above material and spraying it onto a predetermined substrate or the like (thermal spraying). From the viewpoints of ease of handling and reducing loss of raw materials, it is preferable to use a sprayed film formed from the above material as the target material. When the material of the protective film 19 contains at least one of a fluoride and an oxyfluoride, it is preferable that the target material contain a fluoride of the metal contained in the protective film 19.

[0045] For simplicity of explanation, the following description will be given on the case where a thermal sprayed film formed of YOF is used as a target. Note that when a material other than YOF is used as the thermal sprayed film, the following explanation can be understood by replacing YOF with the other material.

[0046] The method for producing the target is not particularly limited, and it can be produced by a general thermal spraying method. For example, a target having a thermal sprayed film of YOF can be obtained by preparing YOF powder and plasma spraying the powder onto a predetermined base, such as a backing plate. The size, position, and shape of the sprayed film can be selected arbitrarily as needed.

[0047] The thickness of the sprayed film made of YOF is not particularly limited, but is preferably, for example, 50 μm or more, since this allows for long-term use.

[0048] The backing plate is used to hold the sprayed film made of YOF and ensure mechanical strength. The backing plate also functions as a heat sink for cooling the sprayed film made of YOF when the target is used in a sputtering process. In addition, the backing plate can have the same functions as backing plates of known sputtering targets.

[0049] The backing plate may be made of the same material as that used for backing plates of known sputtering targets, such as copper, titanium, stainless steel, and aluminum. The shape and size of the backing plate may also be selected as desired.

[0050] As described above, the radio frequency magnetron sputtering method is a sputtering method in which a magnet is placed behind the target and a magnetic field generated on the target surface promotes ionization of the plasma gas, thereby improving the efficiency of sputtering. The radio frequency magnetron sputtering method can be carried out using a known radio frequency magnetron sputtering device.

[0051] Conventionally, protective films made of the above materials (YOF as an example) have been formed as thermal spray films. However, thermal spray films are generally prone to the formation of pores and cracks, making it difficult to ensure corrosion resistance. This tendency is more pronounced as the thickness of the thermal spray film decreases. Therefore, in order to obtain a thermal spray film (YOF film) with sufficient corrosion resistance, it is considered to form the thermal spray film thicker.

[0052] On the other hand, if a thick sprayed film is formed on the mounting surface, the distance between the electrostatic attraction electrode of the electrostatic chuck member and the wafer placed on the mounting surface increases, which raises concerns about a decrease in the Coulomb force that attracts the wafer.

[0053] In contrast, the electrostatic chuck member 10 of this embodiment is configured to form the protective film 19 having a thickness of 0.01 μm or more and 10 μm or less, as described above. Due to the difference in the formation principle between a film formed by magnetron sputtering and a thermal sprayed film, a film formed by magnetron sputtering becomes a dense film even when it is a thin film having a thickness of 0.01 μm or more and 10 μm or less. Therefore, even in a configuration in which the protective film 19 is formed on the mounting surface 10x (the surface 11a of the dielectric substrate 11) as shown in FIG. 1 , it is possible to ensure both sufficient corrosion resistance and sufficient Coulomb force.

[0054] The arithmetic mean roughness Ra of the protective film 19 can be measured using a roughness measuring instrument, for example, a surface roughness and contour shape measuring instrument (Surfcom NEX200, manufactured by Tokyo Seimitsu Co., Ltd.). For example, the arithmetic mean roughness Ra is measured at multiple locations (for example, four locations) of the protective film 19, and the average of the measured values ​​of the arithmetic mean roughness Ra is calculated to obtain the arithmetic mean roughness Ra.

[0055] The arithmetic mean roughness Ra of the protective film 19 may be 2 μm or less, 1 μm or less, 0.1 μm or less, or 0.05 μm or less. The arithmetic mean roughness Ra of the protective film 19 is affected by the arithmetic mean roughness Ra of the dielectric substrate 11. Therefore, it is preferable that the arithmetic mean roughness Ra of the protective film 19 be equal to the arithmetic mean roughness Ra of the dielectric substrate 11. The arithmetic mean roughness Ra of the protective film 19 formed on the flat surface of the dielectric substrate 11 may be 0.1 μm or less, or 0.05 μm or less.

[0056] Furthermore, the protective film 19 can be adhered to the surface of the dielectric substrate 11 without an underlying layer or adhesive layer, even if the surface is flat. Therefore, the arithmetic surface roughness of the surface of the dielectric substrate 11 on which the protective film 19 is provided may be, for example, 2 μm or less, 1 μm or less, 500 nm or less, 250 nm or less, 50 nm or less, or 40 nm or less.

[0057] Here, "the surface of the dielectric substrate 11 is flat" means that the surface of the dielectric substrate 11 is free of irregularities that would provide an anchoring effect for the protective film 19. Therefore, when the protective film 19 is formed on the mounting surface of the dielectric substrate 11 on which a large number of protrusions (convex portions) are intentionally formed, the irregularities formed by the intentionally formed convex portions are not taken into consideration when determining whether the surface of the mounting surface is flat. In this case, the flatness of the surface of the mounting surface can be confirmed by, for example, measuring the arithmetic mean roughness of the top surfaces of the convex portions and determining that the above value is satisfied.

[0058] The protective film 19 is provided on at least a portion of the surface of the dielectric substrate 11 to achieve the effects of the invention. For example, the protective film 19 may be provided on the entire surface of the mounting surface 10x side of the dielectric substrate 11, as shown in FIG. 1 . Alternatively, the protective film 19 may be provided on the peripheral portion (indicated by reference symbol 10y in FIG. 1 ) on the mounting surface 10x side. For example, the protective film 19 may be formed in a doughnut shape (closed ring) in plan view. In this case, the width of the protective film 19 can be selected as needed.

[0059] In Figure 1, the peripheral portion 10y on which the protective film 19 is provided is shown as an area that does not overlap with the electrode 13 in a planar view, but this is not limited to this, and the protective film 19 may be provided up to the area that overlaps with the electrode 13.

[0060] 2 is a schematic cross-sectional view of an electrostatic chuck member 10B according to a modified example of the present embodiment. As in the electrostatic chuck member 10B shown in FIG. 2, the protective film 19 may be provided on the side surface 11x of the dielectric substrate 11. If necessary, the protective film 19 may be provided on only a portion of the side surface.

[0061] The above-described positions for forming the protective film 19 can be combined arbitrarily. For example, in the electrostatic chuck member, the protective film 19 may be provided on the peripheral portion of the side surface and mounting surface side of the dielectric substrate, or may be provided on the entire side surface and mounting surface side of the dielectric substrate. Furthermore, the protective film 19 may be provided on all or at least a portion of the portion of the dielectric substrate 11 that is exposed to the outside when the electrostatic chuck device is completed. When the dielectric substrate 11 has a step for disposing a focus ring, the protective layer 19 may be provided on all or at least a portion of the portion of the dielectric substrate 11 that is not in contact with the focus ring, base, or bonding layer.

[0062] It is preferable that the protective film 19 of this embodiment does not contain carbon (C). Conventionally, when forming an REOF film (RE stands for rare earth element) by sputtering, RE, which is a simple metal, is used as a sputtering target, and oxygen and a reactive gas, CF gas (e.g., HCF ３ A method (reactive sputtering) using a reactive gas containing carbon has been adopted. A film formed by such a method contains carbon contained in the reactive gas. If the protective film 19 contains carbon, the electrical conductivity of the resulting protective film 19 may be affected, which may affect the chucking performance of an electrostatic chuck device.

[0063] However, when the protective film 19 is formed by a radio frequency magnetron sputtering method using a target made of YOF, it is not necessary to use CF gas, which is a reactive gas, during sputtering deposition, and therefore the protective film 19 made of YOF containing no C can be obtained.

[0064] The volume resistivity of the protective film 19 is 1.0×10 ８ Ω・cm or more 1.0×10 ２０ When the volume resistivity of the protective film 19 is in the above range, it is possible to suppress a decrease in the chucking performance of the electrostatic chuck device.

[0065] The volume resistivity of the protective film 19 is 1.0×10 ９ It may be 1.0×10 Ω cm or more, １０ It may be 1.0×10 Ω cm or more,１１ Ω cm or more, and may be 1.0 × 10 １２ It may be 1.0×10 Ω cm or more, １３ The volume resistivity of the protective film 19 may be 1.0×10 １９ It may be Ω cm or less, and may be 1.0 × 10 １８ It may be Ω cm or less, and may be 1.0 × 10 １７ It may be Ω·cm or less.

[0066] 3 is a cross-sectional schematic view showing an example of an electrostatic chuck device 1 according to this embodiment. The electrostatic chuck device 1 includes an electrostatic chuck member 2 and a base 3. The electrostatic chuck member 2 and the base 3 are stacked on top of each other with a bonding layer 4 interposed therebetween.

[0067] <Electrostatic Chuck Member> The electrostatic chuck member 2 has a dielectric substrate 11 and an electrode 13 located inside the dielectric substrate 11. The electrostatic chuck member 2 can have a configuration similar to that of the electrostatic chuck members 10 and 10B described above.

[0068] The electrostatic chuck member 2 has a first attraction portion 21 that attracts and holds the wafer W on its upper surface, and a second attraction portion 22 that attracts and holds the focus ring FR on its upper surface.

[0069] The first suction portion 21 is formed in a cylindrical shape, and has a plurality of upwardly protruding protrusions 211 on its upper surface. In addition, a closed annular protrusion 212 is provided on the periphery of the upper surface of the first suction portion 21 along the edge of the upper surface of the first suction portion 21.

[0070] The electrostatic chuck device 1 supports the wafer W by the tip portions (upper surfaces) of the plurality of convex portions 211 and the upper surface of the annular convex portion 212. That is, in the electrostatic chuck device 1, an imaginary plane connecting the upper surface 212 a of the annular convex portion 212 and the upper surfaces of the plurality of convex portions 211 corresponds to the mounting surface 21 a of the wafer W.

[0071] When a wafer W is placed on the mounting surface 21 a, a space surrounded by the underside of the wafer W, the plurality of protrusions 211, and the annular protrusion 212 functions as a flow path 21 x for flowing a cooling gas. The electrostatic chuck device 1 is provided with a gas supply hole (not shown) that penetrates the electrostatic chuck device 1 in the thickness direction, and the cooling gas is supplied from the gas supply hole to the flow path 21 x. The cooling gas flowing through the flow path 21 x cools the wafer W that is heated during plasma processing.

[0072] The second suction portion 22 has a concentric cylindrical shape with a larger radius than the first suction portion 21, and is formed integrally with the first suction portion 21. An upper surface 22a of the second suction portion 22 is exposed and surrounds the periphery of the first suction portion 21 in a plan view. The upper surface 22a corresponds to a mounting surface that suction-holds the focus ring FR.

[0073] The upper surface 22 a may have a groove formed therein that is annular in plan view. When such a groove is formed, when the focus ring FR is placed on the upper surface 22 a, the space surrounded by the lower surface of the focus ring FR and the groove functions as a flow path for a cooling gas. The electrostatic chuck device 1 may have gas supply holes (not shown) that penetrate the electrostatic chuck device 1 in the thickness direction, and the cooling gas is supplied from the gas supply holes to the flow path. The cooling gas flowing through the flow path cools the focus ring FR, which is heated during plasma processing.

[0074] (Dielectric Substrate) The dielectric substrate 11 is made of ceramics that contains an insulating material and a conductive material, has sufficient mechanical strength, and is durable against corrosive gases and their plasma. The dielectric substrate 11 may have the same structure as the dielectric substrate 11 of the electrostatic chuck members 10 and 10B described above.

[0075] (Electrode for Electrostatic Adsorption) The electrode 13 is disposed inside the dielectric substrate 11. The electrode 13 extends along the mounting surface 21 a of the dielectric substrate 11. When a voltage is applied to the electrode 13, the electrode 13 generates an electrostatic adsorption force that holds the wafer W on the mounting surface 21 a.

[0076] The electrode 15 is disposed inside the dielectric substrate 11. The electrode 15 extends in a circular ring shape in a plan view along the upper surface 22 a of the second attraction portion 22. When a voltage is applied to the electrode 15, the electrode 15 generates an electrostatic attraction force that holds the focus ring FR on the upper surface 22 a.

[0077] The electrodes 13 and 15 are connected to power supply terminals (not shown) for applying a DC voltage to the electrodes 13 and 15, respectively.

[0078] The electrodes 13 and 15 are made of a composite of an insulating material and a conductive material. The materials of the electrodes 13 and 15 may have the same structure as the electrode 13 of the electrostatic chuck members 10 and 10B described above.

[0079] The thickness of the electrostatic chuck member 2 can be selected arbitrarily, but is preferably 0.5 mm or more and 5 mm or less. When the thickness of the electrostatic chuck member 2 is 0.5 mm or more, the withstand voltage of the electrostatic chuck member 2 is high. Furthermore, when the thickness of the electrostatic chuck member 2 is 5 mm or less, the heat capacity of the electrostatic chuck member 2 is small, making it easier to maintain a uniform temperature of the plate-shaped sample, which is the processing target, during plasma processing. The thickness may be 1 mm or more and 4 mm or less, or 2 mm or more and 3 mm or less.

[0080] (Protective Layer on Dielectric Substrate) As with the above-described electrostatic chuck members 10 and 10B, the electrostatic chuck member 2 has the above-described protective film (not shown) on at least a portion of the surface of the dielectric substrate 11. By having the protective film, the electrostatic chuck member 2 can suppress corrosion of the surface of the dielectric substrate 11 by plasma at least in the area where the protective film is provided.

[0081] For example, the electrostatic chuck member 2 may have a protective film made of YOF on the peripheral portion (upper surface 212a of the annular convex portion 212) on the mounting surface 21a side.

[0082] 3 , when the electrostatic chuck device 1 is used to hold a wafer W, a gap (indicated by the symbol α in the drawing) may be formed between the wafer W and the focus ring FR. The upper surface of the electrostatic chuck member 2 (the upper surface 212 a of the annular convex portion 212) is exposed through the gap α. If the surface of the wafer W is etched using plasma in this state, the plasma used in the process may corrode the upper surface 212 a exposed through the gap α, potentially damaging the annular convex portion 212.

[0083] When the electrostatic chuck member 2 has a configuration in which the mounting surface has a plurality of protrusions and the peripheral edge has an annular protrusion 212, damage to the annular protrusion 212 may cause leakage of cooling gas from the flow path 21x. Even if the electrostatic chuck member 2 does not have the annular protrusion 212, damage to the peripheral edge of the mounting surface may likely cause the chucking force at the mounting surface to differ between the center and the peripheral edge. In this case, the temperature of the wafer W during plasma processing may likely vary across the surface, potentially affecting the yield of the plasma process.

[0084] On the other hand, if the electrostatic chuck member 2 has a protective film on the peripheral edge portion on the mounting surface 21a side as described above, damage to the electrostatic chuck member 2 in the plasma process can be preferably suppressed.

[0085] When the electrostatic chuck member 2 has a protective film on the peripheral portion on the mounting surface 21 a side, the protective film may be provided not only on the upper surface 212 a of the annular convex portion 212 but also on the tops of the inner peripheral convex portions 211. In this case, the protective film may be provided continuously also in areas where no convex portions 211 are provided (valleys between the convex portions 211) on the mounting surface 21 a side of the electrostatic chuck member 2. For example, the protective film may be provided on the bottom surfaces between the convex portions 211 and / or on the side surfaces of the convex portions 211, as necessary.

[0086] Furthermore, the electrostatic chuck member 2 may have a protective film on the entire surface of the mounting surface 21 a side. In a semiconductor manufacturing apparatus including the electrostatic chuck device 1, after performing plasma processing on the wafer W, the entire surface of the mounting surface may be plasma-processed without the wafer W being placed thereon in order to clean the upper surface (mounting surface) of the electrostatic chuck device 1. By providing a protective film on the entire surface of the mounting surface 21 a side of the electrostatic chuck member 2, damage to the electrostatic chuck member 2 during the cleaning can be suppressed.

[0087] Furthermore, the electrostatic chuck member 2 may have a protective film on the side surface 2 b of the dielectric substrate 11. The side surface 2 b is always exposed to plasma and is easily damaged. By providing the protective film at such a position, damage to the electrostatic chuck member 2 can be suitably suppressed.

[0088] The positions at which the protective film is formed as described above can be combined arbitrarily. For example, in the electrostatic chuck member 2, the protective film may be provided on the peripheral portion of the side surface and mounting surface side of the dielectric substrate, or on the entire surface of the side surface and mounting surface side of the dielectric substrate.

[0089] <Base> The base 3 is a disc-shaped member in a plan view, and supports the electrostatic chuck member 2 from below. An upper surface 3a of the base 3 faces the lower surface 2a of the electrostatic chuck member 2 in the vertical direction, with the bonding layer 4 interposed therebetween. The base 3 supports the electrostatic chuck member 2 on the upper surface 3a.

[0090] A flow path 3f for circulating a coolant may be provided inside the base 3. The coolant flowing through the flow path 3f may be a fluorine-based inert liquid, water, He gas, N ２ The flow path 3f extends along the upper surface 3a. The coolant in the flow path 3f cools the entire base 3 and also cools the electrostatic chuck member 2 via the upper surface 3a.

[0091] The base 3 is connected to an external high frequency power source 5 via a matching box (not shown), and may also serve as an internal electrode for generating plasma.

[0092] The material of the base 3 is not limited and can be arbitrarily selected and used as long as it is a metal with excellent thermal conductivity, electrical conductivity, and workability, or a composite material containing such a metal, ceramics with high thermal conductivity, conductive ceramics, a composite material of metal and ceramics (MMC: Metal Matrix Composition), etc. For example, aluminum (Al), aluminum alloy, copper (Cu), copper alloy, stainless steel (SUS), ceramics composed of a highly thermally conductive material and a conductive material, etc. are preferably used.

[0093] From the viewpoint of minimizing the difference in thermal expansion coefficient between the base 3 and the dielectric substrate 11, the base 3 is preferably made of a conductive ceramic (hereinafter sometimes abbreviated as "conductive ceramic") containing a highly thermally conductive material and a conductive material. Specifically, when the entire base 3 is taken as 100 volume %, the material of the base 3 has a volume ratio of the highly thermally conductive material to the conductive material (volume of the highly thermally conductive material:volume of the conductive material) of 10:90 to 90:10, preferably 20:80 to 80:20, more preferably 25:75 to 70:30, and even more preferably 30:70 to 60:40. If necessary, the ratio may be 15:85 to 35:65, 35:55 ​​to 55:45, 55:45 to 75:25, or the like.

[0094] The case where the base 3 is made of conductive ceramics will be described in detail below. When a heat transfer medium such as a refrigerant flows through the flow path 3f, frictional charging is expected to occur between the heat transfer medium and the base 3. Since the charge generated in this manner can have adverse effects on the process and the device, it is preferable to quickly remove the charge. However, by using conductive ceramics as the material for the base 3, the charge generated by frictional charging can be easily removed.

[0095] The thermal expansion coefficient of the conductive ceramic material of the base 3 at 800°C is 10×10 －６ / K (10 ppm / K) or less, preferably 9 × 10 －６ / K or less, more preferably 8×10 －６ / K or less. By setting the thermal expansion coefficient of the base 3 to such a value, it is possible to suppress a change in the volume of the base 3 that accompanies a change in the temperature of the base 3 when a heat medium is flowed through the base 3. As a result, distortion is less likely to occur at the interface between the base 3 and the structure in contact with it (the bonding layer 4 in the case of the electrostatic chuck device 1), and damage to the device can be suppressed. Note that the lower limit of the thermal expansion coefficient of the base 3 at 800°C can be selected arbitrarily, but may be set to, for example, 5 × 10 as needed. －６ / K or more, and may be 6×10 －６ / K or more, and may be 6.8 × 10 －６ / K or more.

[0096] The thermal expansion coefficient of the material of the base 3 at 800°C can be determined by the average coefficient of linear expansion (CTE) when the material of the base 3 is subjected to a temperature change from 25°C to 800°C.

[0097] The average linear expansion coefficient when the material (conductive ceramic) of the base 3 is changed in temperature from 25°C to 800°C can be measured using any measuring device, for example, a thermal expansion measuring device (TD5000SA, manufactured by NETZSCH). First, a measurement sample (test piece) made of conductive ceramic is heated from 25°C to 800°C at a temperature increase rate of 5°C / min, and the length (L0) of the measurement sample at 25°C and the length (L1) at 800°C are measured, and the change in length (ΔL) of the measurement sample is measured. The thermal expansion coefficient is calculated by dividing ΔL by the length (L0) of the measurement sample at 25°C, and then the thermal expansion coefficient is calculated by dividing the thermal expansion coefficient by the temperature change width (ΔT = 800°C - 25°C).

[0098] That is, the "coefficient of thermal expansion at 800° C." in this embodiment can be calculated by {(L1−L0) / L0} / ΔT=(ΔL / L0) / ΔT.

[0099] The base 3 is preferably made of a material with a thermal conductivity of 40 W / m·K or more, and more preferably 50 W / m·K to 110 W / m·K. The thermal conductivity may be 45 W / m·K to 100 W / m·K, 60 W / m·K to 90 W / m·K, or 70 W / m·K to 80 W / m·K, as needed. When the thermal conductivity is within the above range, input heat can be effectively dissipated.

[0100] The conductive material can be selected arbitrarily, but SiC, TiO ２ , TiN, TiC, W, WC, Mo, MoC, Mo ２ Preferably, the conductive material is at least one selected from the group consisting of C, TaC, TaN, NbC, VC, and C. Among these, TiN is preferred because of its excellent plasma resistance. Mo and W are preferred because of their high thermal conductivity. As the conductive material, TiN and Mo may be used alone or in combination.

[0101] The high thermal conductivity material can be selected arbitrarily, but examples include AlN, SiC, GaN, and SiO ２ , Al ２ O ３ , SmAlO ３ , MgO, SiO ２ , Si ３ N ４ , Al(OH) ３ , MgO, Mg(OH) ２ , BN, ZnO, BeO, B ４ Preferably, the material is at least one selected from the group consisting of C, carbon (C), aluminum, copper, silver, and gold. Among these, AlN is preferred because of its high thermal conductivity and ease of handling.

[0102] When SiC is used as the highly thermally conductive material, a conductive material other than SiC is selected. When SiC is used as the highly thermally conductive material, for example, TiN can be selected as the conductive material. Similarly, when C is used as the highly thermally conductive material, a conductive material other than C is selected.

[0103] Furthermore, when combining the conductive material and the highly thermally conductive material from the above-mentioned materials, the resulting material preferably contains inorganic oxides, inorganic carbides, inorganic nitrides, and / or inorganic carbonitrides, which belong to either the conductive material or the highly thermally conductive material. Among these, it is preferable to contain inorganic oxides and / or inorganic nitrides. By including these, the resulting material can be said to be preferable as a "conductive ceramic."

[0104] Metal matrix composites (MMCs), which are composite materials of metal and ceramic, are also known as conductive ceramic materials. However, MMCs are generally prepared by preparing a porous ceramic substrate and then introducing molten metals such as Mg, Al, and Si into the pores of the ceramic substrate (metal infiltration method, forging method). Therefore, the metals contained therein are limited to those with relatively low melting points. Such metals may melt depending on the conditions of use of the base 3.

[0105] On the other hand, in the conductive ceramics described above, high melting point metals (Mo: melting point 2622°C, W: melting point 3407°C) with melting points of 1800°C or higher can be used, compared to Mg (melting point 650°C), Al (melting point 660°C), and Si (melting point 1414°C) used as conductive materials in MMCs. Therefore, the base 3 can be suitably used even at high temperatures.

[0106] The thermal expansion coefficient of the dielectric substrate 11 can be selected arbitrarily. ２ O ３ When combined with SiC, the thermal expansion coefficient of the dielectric substrate 11 is ２ O ３ Thermal expansion coefficient (7.8 x 10 －６ / K~8.5 x 10 －６ / K) and the thermal expansion coefficient of SiC at 800°C (4.1 × 10 －６ / K).

[0107] As the highly thermally conductive material contained in the base 3, it is advisable to select a material that can reduce the difference in the thermal expansion coefficient between the dielectric substrate 11 and the base 3, taking into consideration the thermal expansion coefficient of the conductive material to be combined. For example, Al ２ O ３ When using a material with a thermal expansion coefficient larger than that of Al, the high thermal conductivity material to be combined is relatively ２ O ３ A material with a thermal expansion coefficient smaller than that of AlN, for example, is preferred. The thermal expansion coefficient of AlN at 40°C to 800°C is 5.2 × 10 －６It is thought to be around / K.

[0108] The base 3 is made of AlN and TiN (thermal expansion coefficient at 900°C: 7.75 × 10 －６ / K), i.e., an AlN-TiN composite sintered body. It is also preferable that the base 3 be made of conductive ceramics formed from SiC and TiN, i.e., a SiC-TiN composite sintered body.

[0109] The thermal expansion coefficient of the material of the base 3 at 800°C is 6.0 × 10 －６ / K or more 9.0×10 －６ When the thermal expansion coefficient of the material of the base 3 is in the above range, Al ２ O ３ Therefore, when the electrostatic chuck member 2 and the base 3 are joined, distortion is less likely to occur at the interface between the electrostatic chuck member 2 and the base 3. Furthermore, even when the electrostatic chuck device 1 is used at high or low temperatures, distortion is less likely to occur at the interface between the electrostatic chuck member 2 and the base 3. The thermal expansion coefficient of the material of the base 3 at 800°C can be set to 6.5×10 as needed. －６ / K or more 8.5×10 －６ / K or less, 6.8 x 10 －６ / K or more 8.3×10 －６ / K or less or 7.0 x 10 －６ / K or more 8.0×10 －６ / K or less.

[0110] The base 3 may contain one or more sintering aids as needed, as long as the effects of the present invention are not impaired. The amount and type of sintering aid are not particularly limited as long as they are generally added. ２ O ３ , MgO, SiO ２ , CaO, La ２ O ３ , Ce ２ O ３ , Y.O.F., Y.F. ３ Among these, Y ２ O ３ , MgO, SiO ２ , Y.F.３ is preferred.

[0111] The volume resistivity of the base 3 can be selected arbitrarily, but is preferably 1.0×10 －３ The volume resistivity of the base 3 is preferably in the above range, so that sufficient conductivity can be obtained. The lower the volume resistivity of the base 3, the better. However, the lower limit is, for example, 1.0×10 －１０ The volume resistivity of the base 3 may be 1.0×10 Ω·cm or more, if necessary. －８ Ω・cm or more 1.0×10 －４ It may be Ω cm or less, and may be 1.0 × 10 －６ Ω・cm or more 1.0×10 －５ The volume resistivity of the base 3 may be 1.0×10 －６ Ω・cm or more 1.0×10 －５ Ω・cm or less or 1.0×10 －５ Ω・cm or more 1.0×10 －４ Ω・cm or less or 1.0×10 －４ Ω・cm or more 1.0×10 －３ It may be Ω·cm or less.

[0112] The thermal expansion coefficient at 800°C of the material of the base 3 is preferably the same as that of the dielectric substrate 11. The absolute value of the difference between the thermal expansion coefficient at 800°C of the material of the base 3 and the thermal expansion coefficient at 800°C of the material of the dielectric substrate 11 is 2.5×10 －６ / K or less, and preferably 1.5 × 10 －６ / K or less, and more preferably 1.3 × 10 －６ / K or less, and more preferably 1.0 × 10 －６ It is even more preferable that the value is 0.1 / K or less.

[0113] The surface of the base 3 is preferably provided with an alumina sprayed film as required to improve plasma resistance.

[0114] <Bonding Layer> The bonding layer 4 bonds the electrostatic chuck member 2 and the base 3. Any material can be selected for the bonding layer 4, and for example, a known material used for bonding the electrostatic chuck member 2 and the base 3 can be used. For example, the material may be a silicone resin, a silicone resin containing a highly thermally conductive filler such as AlN particles or surface-coated aluminum nitride particles, or an inorganic material such as a metal material. From the viewpoint of controlling the temperature of the electrostatic chuck member 2, the material for the bonding layer 4 is preferably an inorganic material.

[0115] (Bonding Layer Material: Inorganic Material 1) When the inorganic material of the bonding layer 4 is a metal, the material of the bonding layer 4 is preferably an alloy containing 50 vol% to 99.98 vol% of Al or Ag and 0.02 vol% to 40 vol% of at least one metal selected from the group consisting of Ti, Zr, and Hf, when the entire bonding layer 4 is taken as 100 vol%. The proportion of Al or Ag may be, for example, 55 vol% to 95 vol%, 65 vol% to 90 vol%, or 70 vol% to 80 vol%. When the bonding layer 4 contains at least one metal selected from the group consisting of Ti, Zr, and Hf, the molten alloy formed by melting the material of the bonding layer 4 easily wets and spreads over the surface of the ceramic (electrostatic chuck member 2) during bonding between the electrostatic chuck member 2 and the base 3, facilitating bonding. Furthermore, since the bonding layer 4 contains the above metal, the metal and the ceramic (electrostatic chuck member 2) are easily bonded to each other, and the occurrence of voids at the interface can be suppressed, enabling a strong bond.

[0116] The thickness of the bonding layer 4 can be selected arbitrarily, but is preferably 5 μm to 500 μm. The thickness may be 5 μm to 30 μm, 30 μm to 100 μm, or 10 μm to 300 μm.

[0117] When manufacturing the electrostatic chuck device 1, for example, a metal foil or a metal paste obtained by adding a binder to metal powder may be used as the material for forming the bonding layer 4. These materials are placed between the electrostatic chuck member 2 and the base 3 and heated to a temperature equal to or higher than the melting point of the metal material for forming the bonding layer 4, and the molten metal material spreads between the electrostatic chuck member 2 and the base 3, thereby forming the bonding layer 4.

[0118] By using a conductive ceramic as the material for forming the base 3, it is possible to suppress the occurrence of cracks when the base 3 and the electrostatic chuck member 2 are joined (brazed) with a metal material. The mechanism by which the occurrence of cracks is suppressed when the base 3 is joined by brazing by using a conductive ceramic as the material for forming the base 3 is presumed to be as follows.

[0119] The material forming the base must have excellent thermal conductivity, electrical conductivity, and workability. For this reason, it has traditionally been formed from metals such as aluminum. On the other hand, the dielectric substrate that forms the electrostatic chuck member is made from ceramics. In general, the thermal expansion coefficient of ceramics is significantly smaller than that of metals, so there is a large difference in the thermal expansion coefficient between the conventional base made of metal and the electrostatic chuck member made from ceramics.

[0120] For example, when the base material is aluminum, the melting point of aluminum is about 660°C, so there is no thermal expansion coefficient of 800°C. However, the thermal expansion coefficient of the base material (20°C to 100°C) is about 24×10 －６ On the other hand, when the main component of the material of the dielectric substrate 11 constituting the electrostatic chuck member 2 is Al, ２ O ３ In this case, the thermal expansion coefficient (25°C to 800°C) of the material of the dielectric substrate 11 is ２ O ３ Thermal expansion coefficient (7.8 x 10 －６ / K~8.5 x 10 －６ / K). That is, when the base material is aluminum and the main component of the material of the dielectric substrate 11 is Al, ２ O ３ In this case, the thermal expansion coefficient of the material of the dielectric substrate 11 is smaller than the thermal expansion coefficient of the material of the base.

[0121] Joining using metal materials (brazing) is performed at high temperatures of 500°C or higher (e.g., 800°C). Therefore, during brazing, the base and the electrostatic chuck member also become hot. If a metal base is used, tensile stress is likely to occur in the joining layer (brazing material layer) joining the metal base and the ceramic dielectric substrate 11 (electrostatic chuck member) due to the difference in thermal expansion coefficients between the two materials. This stress may cause cracks in the electrostatic chuck member.

[0122] On the other hand, the base 3 employed in the electrostatic chuck device 1 of this embodiment is preferably made of a conductive ceramic. Therefore, the difference in thermal expansion coefficient between the material of the base 3 and the ceramic dielectric substrate 11 is smaller than that of a base made of metal. Furthermore, since the base 3 contains a highly thermally conductive material, it has a sufficiently high thermal conductivity. Furthermore, since the base 3 contains a conductive material, it has a sufficiently high electrical conductivity. Therefore, the tensile stress generated in the bonding layer 4 during brazing bonding of the electrostatic chuck member 2 and the base 3 is reduced, and heat can be effectively dissipated even after bonding. Therefore, in the electrostatic chuck device 1 of this embodiment, cracks can be made less likely to occur in the electrostatic chuck member 2.

[0123] Furthermore, in the electrostatic chuck device 1 formed in this manner, the bonding layer 4 is preferably formed from a metal material (brazing filler metal), and therefore heat can also be effectively released from the bonding layer 4. Therefore, in the electrostatic chuck device 1, it is possible to lower the temperatures of the wafer W, the dielectric substrate 11, the bonding layer 4, and the base 3 relative to the plasma heat input, and stable temperature control is possible.

[0124] (Bonding Layer Material: Inorganic Material 2) When the inorganic material forming the bonding layer 4 is nonmetallic, the material contained in the electrostatic chuck member 2 or the base 3 can be used for the bonding layer 4. For example, an insulating material contained in the dielectric substrate 11 constituting the electrostatic chuck member 2, or a highly thermally conductive material or conductive material contained in the base 3 can be used as needed. By forming a bonding layer using the materials contained in the electrostatic chuck member 2 and the base 3, the electrostatic chuck member 2 and the base 3 can be bonded together. The bonding layer 4 may contain a binder component as long as it does not impair the effects of the invention, but it is preferable that it does not contain a binder. For example, the material forming the bonding layer 4 may contain a binder, and the formed bonding layer 4 may contain no or almost no binder.

[0125] The inorganic material that is the material of the bonding layer 4 may include an insulating material contained in the dielectric substrate 11 that constitutes the electrostatic chuck member 2, and at least one of a highly thermally conductive material and a conductive material contained in the base 3. The bonding layer 4 may include a binder component as long as it does not impair the effects of the invention, but it is preferable that the bonding layer 4 does not include a binder component.

[0126] In this case, the bonding layer 4 can be formed using a bonding material (described later) containing the insulating material and at least one of the high thermal conductivity material and the conductive material. When the bonding layer 4 is to be insulating, the bonding material should contain a high thermal conductivity material but not a conductive material. When the bonding layer 4 is to be conductive, the bonding material should contain a conductive material.

[0127] As the binder component, for example, a resin material can be used. The resin material is preferably one that is resistant to cohesive failure due to thermal stress, and examples thereof include at least one selected from silicone resin, acrylic resin, epoxy resin, phenolic resin, polyurethane resin, unsaturated polyester resin, etc. Among these, silicone resin is preferred because it has a high degree of elasticity and is resistant to cohesive failure due to changes in thermal stress. It is preferable to use a volatile binder component so that no binder component remains after the layers are bonded.

[0128] The ratio of the insulating material to at least one of the highly thermally conductive material and the electrically conductive material in the bonding layer 4 is not particularly limited as long as it bonds the electrostatic chuck member 2 and the base 3. Hereinafter, "at least one of the highly thermally conductive material and the electrically conductive material" may be abbreviated as "highly thermally conductive material, etc."

[0129] In the manufactured electrostatic chuck device 1, if the interface between the bonding layer 4 and the electrostatic chuck member 2 is prone to peeling, it is advisable to increase the proportion of the insulating material in the bonding layer 4. Furthermore, in the electrostatic chuck device 1, if the interface between the bonding layer 4 and the base 3 is prone to peeling, it is advisable to increase the content of the highly thermally conductive material or the like in the bonding layer 4.

[0130] In the bonding layer 4, the volume ratio of the insulating material to the highly thermally conductive material or the like can be selected arbitrarily, and may be, for example, 2:1 to 1:2, or 1:1 to 2:1.

[0131] The content of the binder component in the bonding layer 4 is not particularly limited as long as it bonds the electrostatic chuck member 2 and the base 3. In order to facilitate heat transfer in the bonding layer 4, it is preferable that the bonding layer 4 does not contain a binder component. The bonding layer 4 may contain the binder component in an amount of, for example, 1% by mass to 50% by mass, 10% by mass to 45% by mass, or 20% by mass to 40% by mass.

[0132] The thickness of the bonding layer 4 can be selected arbitrarily, and is preferably 1 μm or more and 50 μm or less, more preferably 5 μm or more and 30 μm or less, and even more preferably 10 μm or more and 20 μm or less.

[0133] The material (bonding material) of the bonding layer 4 may be, for example, a paste-like composition obtained by mixing an insulating material contained in the electrostatic chuck member 2 with a highly thermally conductive material contained in the base 3. The bonding layer 4 is formed between the electrostatic chuck member 2 and the base 3 by stacking the electrostatic chuck member 2 and the base 3 with a coating of the bonding material interposed therebetween, and then heating them under pressure (pressure heating) in a vacuum or in a non-oxidizing atmosphere.

[0134] The resulting bonding layer 4 contains the insulating material that is the material of the electrostatic chuck member 2. Therefore, the bonding layer 4 and the electrostatic chuck member 2 are preferably bonded together by applying pressure and heat.

[0135] Similarly, the resulting bonding layer 4 contains the highly thermally conductive material that is the material of the base 3. Therefore, the base 3 and the bonding layer 4 are preferably bonded together by applying pressure and heat.

[0136] As a result, the electrostatic chuck member 2 and the base 3 are bonded together via the bonding layer 4 .

[0137] According to the electrostatic chuck member having the above-described configuration, the provision of the protective film as described above makes it possible to provide a novel electrostatic chuck member with improved corrosion resistance.

[0138] Furthermore, according to the electrostatic chuck device 1 configured as described above, since the electrostatic chuck member has the protective film as described above, it is possible to provide a novel electrostatic chuck device with improved corrosion resistance.

[0139] Although the electrostatic chuck device 1 has a bonding layer 4, the electrostatic chuck member 2 and the base 3 may be directly bonded to each other without the bonding layer 4 by diffusion bonding the electrostatic chuck member 2 and the base 3.

[0140] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to these examples. The shapes and combinations of the components shown in the above examples are merely examples, and various modifications can be made based on design requirements, etc., without departing from the spirit of the present invention.

[0141] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0142] In this example, a YOF film was formed on a dielectric substrate as a model experiment, and each physical property was evaluated.

[0143] [Preparation of target] The support surface of an aluminum base (backing plate) with a diameter of 100 mm was blasted to roughen the surface, and then Y ５ O ４ F ７The powder was plasma sprayed in the atmosphere to prepare a target made of a sprayed film of YOF on the base.

[0144] [Example 1] Al ２ O ３ -SiC substrate (Al ２ O ３ A target consisting of the obtained YOF sprayed film was prepared on a base and placed in a magnetron sputtering device (model SX-200, manufactured by ULVAC, Inc.). ２ O ３ The Al-SiC substrate was also placed in the device. ２ O ３ A YOF film was formed on the entire surface of one surface of the -SiC substrate, thereby obtaining a dielectric substrate 1 on which a YOF film was formed.

[0145] The obtained dielectric substrate 1 was evaluated as follows.

[0146] (Observation of YOF Film) The obtained YOF film was observed using a scanning electron microscope (manufactured by Hitachi High-Technologies Corporation, Model No. S-4000). As a result, it was confirmed that a dense YOF film was formed on the dielectric substrate 1.

[0147] (Arithmetic mean roughness) The arithmetic mean roughness Ra was measured using a surface roughness / contour shape measuring instrument (Surfcom NEX200, manufactured by Tokyo Seimitsu Co., Ltd.) The arithmetic mean roughness Ra was measured at four points on the YOF film, and the average of the measured values ​​of the arithmetic mean roughness Ra was calculated to obtain the arithmetic mean roughness Ra.

[0148] As a result of evaluation, the Ra of the YOF film on the dielectric substrate 1 was 0.01 μm.

[0149] (Chuck Force Test) An electrostatic chuck member was formed by stacking and adhering an alumina plate, an electrostatic chucking electrode, and the dielectric substrate 1 on which the YOF film was formed in this order. When stacking the components, the YOF film was placed on the opposite side from the electrostatic chucking electrode. The surface on which the YOF film was formed was used as the mounting surface of the electrostatic chuck member.

[0150] In a vacuum (<0.5 Pa), the temperature of the mounting surface was set to 25° C., and a DC voltage of 1.5 kV was applied to the electrostatic adsorption electrode for 60 seconds to adsorb a 1-inch silicon wafer onto the mounting surface.

[0151] The force required to peel off the silicon wafer attracted to the electrostatic chuck member was measured using a load cell, and the maximum stress was taken as the attracting force.

[0152] As a result of the evaluation, it was confirmed that the dielectric substrate 1 has a sufficiently strong chucking force as a result of checking the maximum stress.

[0153] (Voltage Test) Al used in Example 1 ２ O ３ The SiC substrate was processed to a thickness of 0.3 mm, and then Al was applied to the substrate in the same manner as in the production of the dielectric substrate 1. ２ O ３ A test specimen was prepared by forming a YOF film over the entire surface of one side of a SiC substrate. The test specimen was sandwiched between cylindrical electrodes with a diameter of 20 mm. The composite sintered body (test specimen) was then immersed in silicone oil at room temperature, and a high-voltage power supply (manufactured by Matsusada Precision Co., Ltd., model number HGR10-20P) connected to the cylindrical electrodes was used to apply a voltage at a rate of 1 kV / sec. The voltage at which a current of 1 μA flows through the test specimen was measured as the withstand voltage.

[0154] As a result, it was confirmed that the dielectric substrate 1 has excellent withstand voltage.

[0155] (Corrosion Resistance Test) The Al prepared in Example 1 ２ O ３ The SiC substrate and the dielectric substrate 1 obtained in Example 1 were exposed to plasma while being partially masked with a Si wafer. In the case of the dielectric substrate 1, a portion of the YOF film was masked. The exposure to plasma was performed using an etching apparatus (manufactured by Samco Inc., model number RIE-400iPBT) with Ar:CF gas. ４ :O ２The etching was performed with a ratio of 8:1:1, output power of 500 W, and bias of 100 W. After plasma exposure, the mask (Si wafer) was removed, and the step between the surface exposed to the plasma and the surface not exposed to the plasma was measured using a tactile step measurement system (manufactured by Bruker Japan Co., Ltd., model number DekTak XT). The data obtained from the step difference was interpreted as the amount of etching. In addition, a silicon wafer made of silicon was irradiated with plasma under the same conditions, and the step between the exposed surface and the surface not exposed was measured.

[0156] When the etching rate (Si normalized etching rate) was evaluated relative to the etching amount of the silicon wafer obtained from the step, which was set to 100, the Al ２ O ３ The etching depth of the -SiC substrate was 33.9. In contrast, the etching depth of the YOF film on the dielectric substrate 1 obtained in Example 1 was 4.8. The smaller the value, the higher the corrosion resistance.

[0157] As a result of the evaluation, it was found that the YOF film on the dielectric substrate 1 ２ O ３ -It was confirmed that the corrosion resistance was superior to that of SiC substrates.

[0158] (Volume Resistivity) In this example, the volume resistivity (Ω·cm) of the YOF film was measured by the DC three-terminal method as follows.

[0159] (Equipment used) Screen printing machine: Model MEC-2400, manufactured by Mitani Micronics Co., Ltd. Resistivity measuring device: manufactured by Nishiyama Manufacturing Co., Ltd. Digital ultra-high resistance / microcurrent meter (Model 5450, manufactured by ADC Corporation)

[0160] (Measurement conditions) Measurement temperature: room temperature (24°C) Measurement atmosphere: air (flow rate 200 ml / min) Applied voltage: 500 V

[0161] (Measurement method) Al ２ O ３Except for using a Ti substrate instead of the SiC substrate, a YOF film for measuring volume resistivity was obtained on one surface of the Ti substrate in the same manner as in Example 1. A silver paste (US-202A, manufactured by Daiken Chemical Manufacturing Co., Ltd.) was printed on the upper surface of the YOF film using a screen printer and dried in air at 150°C for 12 hours to form a main electrode and a guard electrode.

[0162] At this time, the diameter of the main electrode was 1.45 cm, and the inner diameter of the guard electrode was 1.60 cm.

[0163] A DC voltage was applied to the YOF film on which the main electrode, guard electrode, and counter electrode (Ti substrate) were formed, and the current after charging for 1 minute was measured to determine the volume resistance (Rv) of the YOF film. Next, the volume resistivity (ρv) was calculated using the film thickness of the YOF film and the area of ​​the electrodes according to the following formula (1): ρv = S / t × Rv = S / t × V / I (1), where S is the effective area of ​​the electrode (cm ２ ), t: thickness of YOF film (cm), Rv: volume resistance (Ω), V: DC voltage (V), I: current (A)

[0164] As a result, the volume resistivity of the YOF film was 1.3 × 10 １２ The resistance was Ω / cm.

[0165] DESCRIPTION OF SYMBOLS 1 Electrostatic chuck device, 11 Dielectric substrate, 2, 10, 10B Electrostatic chuck member, 2a Lower surface of electrostatic chuck member 2b, 11x Side surface, 3 Base, 3a Upper surface of base 3f, 21x Flow path, 4 Bonding layer, 5 High frequency power supply 10x, 21a Mounting surface, 10y Peripheral edge portion of dielectric substrate on mounting surface side 11a Surface, 13, 15 Electrostatic attraction electrode, 19 Protective film, 21 First attraction portion 22 Second attraction portion 22a Upper surface of second attraction portion 211 Convex portion, 212 Annular convex portion 212a Upper surface of annular convex portion FR Focus ring, W Wafer α Gap between wafer and focus ring

Claims

1. An electrostatic chuck member comprising: an electrostatic attraction electrode; and a plate-shaped dielectric substrate containing the electrostatic attraction electrode and having a mounting surface on which a plate-shaped sample is placed, the dielectric substrate having a protective film on at least a portion of the surface of the dielectric substrate, the protective film being formed from at least one ceramic material selected from the group consisting of oxides, fluorides, and oxyfluorides, the material including at least one selected from the group consisting of rare earth elements, Mg, Ca, Al, Si, and Zr, and the thickness of the protective film being 0.01 μm or more and 10 μm or less.

2. The electrostatic chuck member according to claim 1, wherein the protective film is provided on the peripheral edge of the dielectric substrate on the mounting surface side.

3. The electrostatic chuck member according to claim 2, wherein the protective film is provided on the entire surface of the mounting surface side of the dielectric substrate.

4. An electrostatic chuck member according to any one of claims 1 to 3, wherein the protective film is provided on a side surface of the dielectric substrate.

5. The volume resistivity of the protective film is 1.0×10 ８ Ω・cm or more 1.0×10 ２０ 4. The electrostatic chuck member according to claim 1, wherein the electrostatic resistance is Ω·cm or less.

6. An electrostatic chuck device comprising: an electrostatic chuck member according to any one of claims 1 to 3; and a base supporting said electrostatic chuck member from said one surface side.

7. An electrostatic chuck device according to claim 6, further comprising a bonding layer that bonds said electrostatic chuck member and said base.

8. An electrostatic chuck device according to claim 6, wherein the base is made of conductive ceramics, the conductive ceramics being composed of a highly thermally conductive material and a conductive material, and the volume ratio of the highly thermally conductive material to the conductive material is 10:90 to 90:10.

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