Electrostatic chuck and electrostatic chuck device

Abstract

This electrostatic chuck comprises: a substrate that has a first surface for holding a workpiece, and a second surface positioned on the opposite side from the first surface; and an electrode layer that is positioned on the second-surface side. The substrate has a plurality of first regions that overlap the electrode layer in plan view. Provided between adjacent first regions are second regions that are positioned between the substrate and the second surface and have a dielectric constant lower than that of the first regions. The relationship 0.5 × t1 ≤ t2 < t1 is satisfied by t1 and t2, where t1 is the thickness of the first regions from the first surface to the second surface, and t2 is the thickness of the second regions.

Description

Electrostatic chuck and electrostatic chuck device

[0001] The present disclosure relates to electrostatic chucks and electrostatic chuck devices.

[0002] Electrostatic chucks for holding a substrate, which is an object to be processed, are known, as disclosed in Japanese Patent Application Laid-Open Nos. 2003-229999 and 2003-229999.

[0003] JP 2005-223185 A JP 2002-368069 A

[0004] An electrostatic chuck according to one aspect of the present invention includes a substrate having a first surface for holding a workpiece and a second surface opposite the first surface, and an electrode layer located on the second surface side. The substrate has a plurality of first regions overlapping the electrode layer in a plan view. A second region is located between adjacent first regions and between the substrate and the second surface, and has a lower dielectric constant than the first regions. When the thickness of the first region from the first surface to the second surface is t1 and the thickness of the second region is t2, t1 and t2 satisfy the relationship 0.5 × t1 ≦ t2 < t1. Note that the thickness refers to the length of the region in the direction from the first surface toward the second surface.

[0005] FIG. 1 is a longitudinal sectional view showing an example of an electrostatic chuck device according to a first embodiment. FIG. 2 is a sectional view taken along the arrows A-A shown in FIG. 1. FIG. 3 is an enlarged sectional view of a main portion of the electrostatic chuck device shown in FIG. 1. FIG. 4 is a sectional view showing another example of an electrostatic chuck device according to the first embodiment. FIG. 5 is a longitudinal sectional view showing an example of an electrostatic chuck device according to a second embodiment. FIG. 6 is a sectional view taken along the arrows B-B shown in FIG. 5. FIG. 7 is an enlarged sectional view of a main portion of the electrostatic chuck device shown in FIG. 5. FIG. 8 is a sectional view showing another example of an electrostatic chuck device according to the second embodiment.

[0006] The electrostatic chuck described above has room for improvement, for example, in terms of improving the performance of holding the object to be processed.

[0007] Therefore, it is expected that the performance of holding the object to be processed can be improved.

[0008] Hereinafter, embodiments of an electrostatic chuck and an electrostatic chuck device disclosed in the present application will be described in detail. However, the present disclosure is not limited to the embodiments described below.

[0009] 1 is a vertical cross-sectional view showing an example of an electrostatic chuck device according to a first embodiment, and FIG 2 is a cross-sectional view taken along line AA shown in FIG 1.

[0010] 1 and 2 , an electrostatic chuck device 100 according to this embodiment includes an electrostatic chuck 1. The electrostatic chuck 1 attracts and holds a sample, such as a semiconductor wafer, by using electrostatic force. The electrostatic chuck 1 includes a substrate 10 and an electrode layer 20.

[0011] The substrate 10 has a first surface 10a and a second surface 10b. The first surface 10a is a sample support surface that supports the object to be processed. The second surface 10b is located on the opposite side of the first surface 10a. The distance from the first surface 10a to the second surface 10b, i.e., the thickness of the substrate 10, may be, for example, 0.3 mm to 2 mm. Note that the thinner the substrate 10, the narrower the distance between the first surface 10a and the electrode layer 20, and therefore the greater the holding force.

[0012] The substrate 10 may contain Al, Si, Mn, Ti, Fe, and Mg. The substrate 10 may also contain a plurality of metal oxides.

[0013] The substrate 10 is Al ２ O ３ The substrate 10 may contain 90% by mass or more of Al in terms of Al content. The substrate 10 may contain 90% by mass or more and 95% by mass or less of Al. The Al content may be adjusted depending on the contents of other components described below.

[0014] The substrate 10 is made of SiO ２ The substrate 10 may contain 0.4 mass % or more and 2.5 mass % or less of Si, calculated as SiO. This makes it easier to obtain a density sufficient for the intended use, and makes it easier to obtain a substrate 10 with high strength. ２ The Si content may be 0.9 mass % or more and 2.0 mass % or less in terms of Si content. With such a composition, it is easy to obtain a substrate 10 that is particularly strong and lightweight.

[0015] The substrate 10 is made of MnO ２ The Mn content may be 3.0 mass % or more and 3.7 mass % or less in terms of Mn content, which facilitates obtaining a high-strength substrate 10. Furthermore, it facilitates obtaining an electrostatic chuck 1 with improved performance for holding an object to be processed.

[0016] The substrate 10 is made of TiO ２ The titanium content may be 1.1 mass % or more and 1.7 mass % or less in terms of titanium content, which makes it easier to obtain a substrate 10 with high strength.

[0017] The substrate 10 is made of Fe ２ O ３ The substrate 10 may contain 1.1 mass % or more and 1.7 mass % or less of Mn, calculated as a conversion amount, which makes it easier to obtain a substrate 10 with high strength.

[0018] Furthermore, the substrate 10 may contain 0.05% by mass or more and 0.3% by mass or less of Mg, calculated as MgO, which makes it difficult for grain growth to occur in the substrate 10, making it easier to obtain a substrate 10 with high strength.

[0019] The substrate 10 may be black. ＊ , b ＊ and L ＊ The ΔE calculated based on a may be 36 or less. ＊ , b ＊ and L ＊ is CIE1976 (L) in accordance with JIZ Z 8781-4 2013 ＊ a ＊ b ＊ ) color space based values. ＊ , b ＊ and L ＊ can be measured at wavelengths of 400 nm to 700 nm using a spectrophotometer, for example, a CM-700d manufactured by Konica Minolta. The field of view of the measurement may be 10°. The main light source may be D65, and the illumination diameter may be measured under measurement conditions such as an aperture diameter of φ6 mm (SAV), SCE (specular reflection removed), and measurement after white calibration. Furthermore, the reflectance may be measured, for example, using a CM-2600d manufactured by Konica Minolta, under conditions of SCE (specular reflection removed), and wavelengths of 360 nm to 740 nm.＊ , b ＊ and L ＊ can be adjusted by the composition of the metal oxide contained in the substrate 10 as well as the baking temperature and baking time. ＊２ +b ＊２ +L ＊２ ) ０．５ If the value of ΔE is 0, a ＊ , b ＊ , L ＊ This means that all values ​​of ΔE are 0, which means that the color is black. Conversely, a larger ΔE value means that the color is farther from black. In other words, a ΔE of 36 or less can be said to be sufficiently close to black.

[0020] By making the substrate 10 black, members other than the substrate 10, such as the electrode layer 20, are less likely to be visible from the first surface 10a side, thereby providing an electrostatic chuck 1 with excellent concealability. Furthermore, when the electrostatic chuck device 100 is equipped with a heater (not shown), for example, radiant heat from the substrate 10 can be expected, allowing the electrostatic chuck 1 to be heated quickly.

[0021] In addition, the substrate 10 of the present disclosure has a volume resistivity of 10 ９ The insulating film 10 may have a resistance to deformation of Ω·m or more and a three-point bending strength of 310 MPa or more. This allows the substrate 10 to have relatively high insulation resistance and physical strength and to be less susceptible to cracking.

[0022] The metal elements contained in the substrate 10 of the present disclosure can be quantified using an X-ray fluorescence analyzer (XRF). The content of each metal element obtained by the measurement is converted into a metal oxide to obtain the content of each metal element. Specifically, for example, Al is Al ２ O ３ , Si is SiO ２ Mn is MnO ２ Ti is TiO ２ , Fe is Fe ２ O ３ In addition, when the substrate 10 contains other metal elements, the values ​​may be converted into representative metal oxides of the respective elements.

[0023] Furthermore, the substrate 10 of the present disclosure may not contain Co and Cr. In such a case, the substrate 10 of the present disclosure can be provided at low cost because it does not use expensive Co and Cr. Note that "not containing Co and Cr" means that the content of Co and Cr is below the detection limit of an X-ray fluorescence analyzer (XRF).

[0024] The electrode layer 20 of the present disclosure includes a pair of electrodes 21 and 22. The electrode layer 20 is a comb-like electrode in which the electrodes 21 and 22 are alternately arranged. The electrostatic chuck 1 having the electrode layer 20 in this shape can hold, for example, an insulator workpiece on the first surface 10a by a gradient force generated by, for example, applying a positive voltage to the electrode 21 and a negative voltage to the electrode 22. Note that when holding the workpiece by gradient force, the holding force can be increased by narrowing the width between the electrodes.

[0025] The electrode layer 20 is a conductive member containing a metal such as copper, aluminum, titanium, gold, platinum, tungsten, or molybdenum. The thickness of the electrode layer 20 may be, for example, about 1 mm to 100 μm. The width of the electrode layer 20 may be, for example, about 1 mm to 10 mm. The interval between adjacent electrode layers 20 may be, for example, about 0.2 mm to 2 mm.

[0026] The electrostatic chuck device 100 of the present disclosure may further include a base member 50 and a bonding material 40. The base member 50 is bonded to the second surface 10b of the substrate 10 and the electrode layer 20 via the bonding material 40. The base member 50 may be a heat exchanger that receives heat from the substrate 10 and dissipates the heat to the outside. The base member 50 may have a flow path (not shown) through which a cooling medium flows. The base member 50 may be made of a metal such as aluminum or titanium. In such a case, the base member 50 may also serve as an RF electrode for the substrate 10, for example.

[0027] The bonding material 40 is located between the second surface 10b of the substrate 10 and the electrode layer 20 and the base member 50, and bonds the electrostatic chuck 1 and the base member 50. The bonding material 40 may be, for example, a polyimide resin, a silicone resin, or an acrylic resin. Such polyimide resin may have a relative dielectric constant of, for example, about 4 to 5. The silicone resin may have a relative dielectric constant of, for example, about 2 to 5. The acrylic resin may have a relative dielectric constant of, for example, about 2 to 4. The bonding material 40 may contain, for example, a filler.

[0028] In this way, by further comprising the base member 50 and the bonding material 40, the electrostatic chuck device 100 becomes a composite of the electrostatic chuck 1, the bonding material 40, and the base member 50, and therefore the electrostatic chuck device 100 of the present disclosure has improved durability, for example.

[0029] <Main Parts of Electrostatic Chuck Device> Next, the main parts of the electrostatic chuck device 100 of the present disclosure will be further described with reference to Figures 1 to 3. Figure 3 is an enlarged cross-sectional view of the main parts of the electrostatic chuck device shown in Figure 1.

[0030] The substrate 10 of the present disclosure has a plurality of first regions 11. The first regions 11 refer to portions that overlap with the electrode layer 20 in a planar view. In other words, when the substrate 10 is viewed from the first surface 10a side, the portions that overlap with the electrode layer 20 are the first regions 11. In the first regions 11, the second surface 10b of the substrate 10 and the electrode layer 20 are in contact with each other.

[0031] The electrostatic chuck 1 of the present disclosure also has a second region 30 between adjacent first regions 11. The second region 30 is located between the substrate 10 and the second surface 10b. The second region 30 is a space in the substrate 10 located between adjacent first regions 11 and opening to the second surface 10b. The second region 30 has a lower dielectric constant than the first region 11. The magnitude of the dielectric constants in the first region 11 and the second region 30 can be evaluated by comparing the relative dielectric constants in the first region 11 and the second region 30. The second region 30 of the present disclosure may contain air. The second region 30 of the present disclosure may be under negative pressure or vacuum.

[0032] Furthermore, as shown in FIG. 3, when the thickness of the first region 11 from the first surface 10a to the second surface 10b is t1 and the thickness of the second region 30 is t2, t1 and t2 have a relationship of 0.5×t1≦t2<t1.

[0033] In the electrostatic chuck 1 having such a second region 30, the holding performance of the workpiece on the first surface 10a is improved compared to the electrostatic chuck 1 of the present disclosure that does not have the second region 30. The reasons for this include, for example, that the spacing between the electric field lines is wider inside the second region 30 compared to the first region 11, and that the electric field lines are less likely to penetrate into the second region 30, which has a dielectric constant different from that of the first region 11.

[0034] The first region 11 of the present disclosure may have, for example, a relative dielectric constant of 3 to 10. The second region 30 of the present disclosure may have, for example, a relative dielectric constant of about 1.

[0035] Furthermore, the bonding material 40a may be located inside the second region 30. For example, the bonding material 40a may be a portion of the bonding material 40 located between the substrate 10 and the base member 50 and between the electrode layer 20 and the base member 50 that has penetrated into the second region 30. In other words, the bonding material 40 may extend into the second region 30. This makes it easier for an anchor effect to occur between the second region 30 and the bonding material 40a, which may improve the durability of the electrostatic chuck device 100.

[0036] The shape of the electrostatic chuck 1 of the present disclosure may be, for example, a substantially cylindrical shape. The electrostatic chuck 1 may have a shape other than a cylindrical shape. FIG. 4 is a cross-sectional view showing another example of the electrostatic chuck device according to the first embodiment. The shape of the electrostatic chuck 1 may be, for example, a substantially rectangular pillar shape. In addition, the arrangement of the electrode layers 20 shown in FIGS. 2 and 4 is merely an example, and can be changed depending on the performance required of the electrostatic chuck 1.

[0037] Second Embodiment Fig. 5 is a vertical cross-sectional view showing an example of an electrostatic chuck device according to a second embodiment, and Fig. 6 is a cross-sectional view taken along line BB shown in Fig. 5 .

[0038] 5 and 6 , an electrostatic chuck device 100 according to this embodiment includes an electrostatic chuck 1. The electrostatic chuck 1 attracts and holds a sample, such as a semiconductor wafer, by using electrostatic force. The electrostatic chuck 1 includes a substrate 10 and an electrode layer 20. Note that detailed description of the same components as those of the electrostatic chuck device 100 according to the first embodiment will be omitted.

[0039] <Main Parts of Electrostatic Chuck Device> Next, the main parts of the electrostatic chuck device 100 of the present disclosure will be further described with reference to Figures 5 to 7. Figure 7 is an enlarged cross-sectional view of the main parts of the electrostatic chuck device shown in Figure 5.

[0040] The substrate 10 of the present disclosure has a plurality of first regions 11. The electrostatic chuck 1 of the present disclosure also has second regions 30 between adjacent first regions 11. The second regions 30 are located between the substrate 10 and the second surface 10b. The second regions 30 have a lower dielectric constant than the first regions 11.

[0041] Furthermore, as shown in FIG. 7, when the thickness from the first surface 10a to the second surface 10b of the first region 11 is defined as t3 and the thickness of the second region 30 is defined as t4, t3 and t4 have the relationship 0.5×t3≦t4<t3.

[0042] In this way, the electrostatic chuck 1 of the present disclosure has improved performance for holding the workpiece on the first surface 10 a compared to an electrostatic chuck 1 that does not have the second region 30 .

[0043] Furthermore, the bonding material 40a may be located inside the second region 30. This makes it easier for an anchor effect to occur between the second region 30 and the bonding material 40a, which improves the durability of the electrostatic chuck device 100. For example, the bonding material 40a may be located so as to fill the inside of the second region 30. For example, the bonding material 40a may be located only in a part of the second region 30.

[0044] The shape of the electrostatic chuck 1 according to the present disclosure may be, for example, substantially cylindrical. The electrostatic chuck 1 may have a shape other than cylindrical. FIG. 8 is a cross-sectional view showing another example of an electrostatic chuck device according to the second embodiment. The shape of the electrostatic chuck 1 may be, for example, substantially rectangular. The shape of the electrode layer 20 in plan view may be a shape corresponding to the substrate 10, such as a rectangle. Note that although the above example shows a case where the electrostatic chuck 1 is a so-called bipolar electrostatic chuck device 100, the electrostatic chuck 1 may also be a monopolar electrostatic chuck. When the electrostatic chuck 1 is a monopolar electrostatic chuck, the electrode layer 20 may have only one electrode.

[0045] Next, an example of a method for manufacturing the electrostatic chuck 1 of the present disclosure will be described.

[0046] Particulate or powdered Al ２ O ３ , Fe ２ O ３ and MnO ２ and TiO as a sintering aid. ２ , SiO ２ and MgO are added. The particle size of each raw material powder may be, for example, 0.1 μm to 5 μm. Water and an optional binder are added, mixed, and stirred, and the resulting slurry is used, or the slurry is spray-dried into granules to produce a molded body of the desired shape, which is then fired in an oxidizing atmosphere, thereby obtaining the substrate 10 of the present disclosure. Note that known methods such as press molding, doctor blade method, and roll compaction method can be used to produce the molded body.

[0047] The firing temperature may be, for example, 1350° C. or higher and 1550° C. or lower. The firing time may be, for example, about 2 hours. The firing atmosphere may be air.

[0048] An electrode layer 20 is disposed on the second surface 10b of the obtained substrate 10. Examples of methods that can be used include, but are not limited to, electroless plating, electrolytic plating, sputtering, ion plating, physical vapor deposition, chemical vapor deposition, and vacuum deposition.

[0049] Furthermore, the second region 30 is formed between adjacent electrode layers 20. For example, sandblasting, shot blasting, etc. can be exemplified, but are not limited to these. Furthermore, the cross-sectional shape of the second region 30 is not limited to the shapes exemplified in, for example, Figures 3 and 7, and can be a shape depending on the method for forming the second region 30.

[0050] Ceramic sintered bodies with different compositions and shapes suited to each test were prepared, and the mechanical strength (three-point bending strength), volume resistivity, and a ＊ , b ＊ and L ＊ The measurement was carried out. ＊ , b ＊ and L ＊ ΔE was calculated based on the following relational expression (Equation 1): ＊ , b ＊ and L ＊ Unless otherwise specified, the values ​​are measured on the sintered surface of the sintered body.

[0051] (Equation 1) ΔE = (a ＊２ +b ＊２ +L ＊２ ) ０．５

[0052] The test piece sizes for each test were as follows: Transverse strength: 3 mm x 4 mm x 50 mm prismatic body; Color: Φ18 mm x 3 mm cylindrical body; Volume resistivity: 60 mm x 60 mm x 2 mm

[0053] First, Al ２ O ３ powder and SiO ２ powder and MnO ２ powder and TiO ２ powder and Fe ２ O ３ Powder and MgO powder were prepared.

[0054] In the sintered ceramics, the oxide of Al (Al ２ O ３ ) converted to silicon oxide (SiO ２ ) converted to Mn oxide (MnO ２ ) equivalent, Ti oxide (TiO ２) equivalent, Fe oxide (Fe ２ O ３ The mass ratios of the magnesium oxide (MgO) and magnesium oxide (MgO) were calculated as shown in Table 1.

[0055] Next, the weighed powders were mixed and molded to obtain a molded body having a desired shape.

[0056] Next, the compact was fired in a firing furnace in an air (oxidizing) atmosphere to obtain a sintered body as each sample.

[0057] Next, each sample was measured using XRD to confirm the presence of aluminum oxide (alumina). Furthermore, each sample was mirror-polished and then measured for Al, Si, Mn, Ti, Fe, and Mg using XRF to determine the content of each element. The determined element content was converted into the content of each oxide, and the content of each element shown in Table 1 was calculated.

[0058] Furthermore, the three-point bending strength of the obtained sintered body was measured in accordance with JIS R 1601-2008, and the results are shown in Table 1.

[0059] The volume resistivity was measured in accordance with JIS C 2141:1992, and the results are shown in Table 1.

[0060] The obtained sintered body was subjected to a CIE1976 (L) test in accordance with JIS Z 8722-2000. ＊ a ＊ b ＊ ) based on color space a ＊ , b ＊ and L ＊ The results are shown in Table 1.

[0061] Furthermore, the electrostatic chuck 1 was fabricated using the obtained sintered body.

[0062]

[0063] As shown in Samples No. 1 and 4, SiO ２ When the Si content was less than 0.4 mass % or more than 2.5 mass % in terms of converted value, the three-point bending strength was less than 310 MPa, and the resulting ceramic sintered body had poor bending strength.

[0064] Furthermore, as shown in Samples No. 5 and 8, when the Mg content was less than 0.05 mass % or more than 0.3 mass % in terms of MgO, the three-point bending strength was less than 310 MPa, and ceramic sintered bodies having poor bending strength were obtained.

[0065] Furthermore, as shown in sample No. 9, TiO ２ When the content of Ti was less than 1.1 mass % in terms of converted value, ΔE exceeded 36. ＊ and b ＊ is over 2.0, L ＊ As shown in Sample No. 12, a ceramic sintered body having a SiO2 content of more than 36 was obtained. ２ When the Ti content exceeded 1.7 mass % in terms of converted value, the three-point bending strength was less than 310 MPa, and the resulting ceramic sintered body had poor bending strength.

[0066] Furthermore, as shown in sample No. 13, MnO ２ When the Mn content is less than 3.0 mass % in terms of Mn, b ＊ As shown in sample No. 17, a ceramic sintered body having a porosity of more than 2.0 was obtained. ２ When the Mn content exceeded 3.7 mass % in terms of conversion, the three-point bending strength was less than 310 MPa, and the resulting ceramic sintered body had poor bending strength.

[0067] Moreover, as shown in sample No. 18, Fe ２ O ３ When the content of Fe was less than 1.1 mass % in terms of iron conversion, ΔE exceeded 36. ＊ As shown in sample No. 21, a ceramic sintered body having a SiO2 content of more than 36 was obtained. ２ O ３ When the content of Fe exceeds 1.7 mass % in terms of Fe content, ＊ and b ＊ A ceramic sintered body having a porosity of more than 2.0 was obtained.

[0068] In contrast, as shown in Samples Nos. 2, 3, 6, 7, 10, 11, 14-16, and 19, Al ２ O ３ 90 mass % or more of Al converted into SiO ２0.4 mass % or more and 2.5 mass % or less of Si converted to MnO ２ 3.0 mass % or more and 3.7 mass % or less of Mn and TiO ２ 1.1 mass % or more and 1.7 mass % or less of Ti converted to Fe ２ O ３ The ceramic sintered body containing 1.1 mass % or more and 1.7 mass % or less of Fe converted into MgO and 0.05 mass % or more and 0.3 mass % or less of Mg converted into MgO has a volume resistivity of 10 ９ The tensile strength was Ω·m or more, and the three-point bending strength was 310 MPa or more. Thus, the ceramic sintered body of the present disclosure has relatively high insulation resistance and physical strength. Furthermore, the ceramic sintered body of the present disclosure had a ΔE of 36 or less. ＊ and b ＊ is 0 or more and 2.0 or less, L ＊ was 0 or more and 36 or less, and the color was black.

[0069] Next, a molded body having the same composition as Sample No. 15 in Table 1 was fired at a temperature 50° C. lower than that of Sample No. 15 to produce a ceramic sintered body. The properties of the sintered body are shown in Table 2.

[0070]

[0071] Sample No. 22a in Table 2 ＊ , b ＊ , L ＊ and ΔE are values ​​obtained by measuring the baked surface in the same manner as in Table 1. ＊ , b ＊ , L ＊ and ΔE are values ​​measured on a mirror-finished surface, i.e., a mirror surface. In the ceramic sintered body of the present disclosure, when mirror-finishing is performed, L ＊ On the other hand, in the ceramic sintered body of the present disclosure, when mirror finishing is performed, a ＊ and b ＊tended to be larger. Note that the firing temperature had little effect on the strength of the ceramic sintered body of the present disclosure. In terms of reflectance, the ceramic sintered body of the present disclosure exhibited a reflectance of 15% or less. Furthermore, the ceramic sintered body of the present disclosure exhibited a reflectance of 12% or less on the mirror surface. Furthermore, when comparing the fired surface and the mirror surface of the ceramic sintered body of the present disclosure, the mirror surface tended to have a lower reflectance.

[0072] Thus, if the ceramic sintered body has the above-described composition, it has good volume resistivity and color and also high mechanical strength, so that even if it is manufactured into an electrostatic chuck and the thickness of the second region is increased, breakage in the second region is unlikely to occur. Therefore, it can be used as a substrate that is resistant to cracks in the electrostatic chuck of the present disclosure.

[0073] The present disclosure has been described in detail above, but the present disclosure is not limited to the above-described embodiments, and various modifications, improvements, etc. are possible within the scope that does not deviate from the gist of the present disclosure.

[0074] Further advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

[0075] REFERENCE SIGNS LIST 1 electrostatic chuck 10 substrate 10a first surface 10b second surface 11 first region 20 electrode layer 30 second region 40 bonding material 50 base member

Claims

1. An electrostatic chuck comprising: a substrate having a first surface for holding a workpiece and a second surface located opposite the first surface; and an electrode layer located on the second surface side, wherein the substrate has a plurality of first regions overlapping the electrode layer in a plan view; and between adjacent first regions there is a second region located between the substrate and the second surface and having a lower dielectric constant than the first regions; wherein t1 is the thickness of the first region from the first surface to the second surface, and t2 is the thickness of the second region, and t1 and t2 satisfy the relationship 0.5 × t1≦t2<t1.

2. The substrate is Al ２ O ３ 90% by mass or more of Al converted into SiO ２ 0.4 mass % or more and 2.5 mass % or less of Si converted into MnO ２ 3.0 mass % or more and 3.7 mass % or less of Mn converted to TiO ２ 1.1 mass % or more and 1.7 mass % or less of Ti converted into Fe ２ O ３ 2. The electrostatic chuck according to claim 1, comprising: 1.1 mass % or more and 1.7 mass % or less of Fe, calculated as an FeO equivalent; and 0.05 mass % or more and 0.3 mass % or less of Mg, calculated as an MgO equivalent.

3. An electrostatic chuck device comprising: the electrostatic chuck according to claim 1 or 2; a base member; and a bonding material positioned between the second surface and the electrode layer and the base member, for bonding the electrostatic chuck and the base member.

4. The electrostatic chuck device according to claim 3, wherein the bonding material extends into the second region.

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