Electrostatic chuck and handling device

Abstract

The present invention provides an electrostatic chuck and a processing device. The electrostatic chuck is a Johnson-Rabec force type electrostatic chuck comprising a metal substrate, an electrostatic adsorption electrode disposed on the metal substrate via an insulating layer, and a dielectric layer forming an electrostatic adsorption surface in contact with a processed object. In the electrostatic chuck, the dielectric layer comprises a ceramic spray coating and a sealing component filled into the pores of the ceramic spray coating, wherein the sealing component comprises a metal organic acid salt containing a rare earth element.

Description

Technical Field

[0001] The present invention relates to an electrostatic chuck and a processing device comprising the electrostatic chuck. Background Art

[0002] During the manufacturing process of semiconductor devices, an electrostatic chuck is used to hold a semiconductor wafer. Known examples of electrostatic chucks include a chuck electrode disposed on a metal mounting table with an insulating layer interposed therebetween. A ceramic dielectric layer is then laminated to cover the chuck electrode. The surface of the dielectric layer serves as an electrostatic attraction surface for holding the semiconductor wafer.

[0003] Electrostatic chucks are placed inside plasma processing equipment, such as plasma etching equipment. The electrostatic adsorption surface of an electrostatic chuck placed inside a plasma processing equipment must be resistant to corrosion by plasma gas or cleaning fluids. This is because the electrostatic chuck is used repeatedly.

[0004] For example, plasma etching equipment performs a cleaning step for each semiconductor wafer or each batch to remove reaction products from the processed material adhering to the inner wall of the etching chamber. This cleaning step involves plasma cleaning using, for example, a halogen such as fluorine (F) or a mixed gas containing a halogen. During this cleaning step, the electrostatically attracted surface of the electrostatic chuck is also exposed to the plasma gas used for plasma cleaning.

[0005] Therefore, it has been proposed to provide a protective layer on the electrostatically attracted surface of an electrostatic chuck disposed within a plasma processing apparatus to prevent corrosion caused by plasma gases (including those used in cleaning steps) or cleaning fluids. Methods for forming the protective layer include physical vapor deposition (PVD), chemical vapor deposition (CVD), sputtering, and coating. Among these, sputtering, which can form a ceramic coating (e.g., yttrium oxide) with a thickness of approximately several hundred microns, is a suitable method for forming a highly corrosion-resistant protective layer.

[0006] On the other hand, films formed by spraying often have pores. To plug these pores, a post-treatment called pore sealing is sometimes performed. While pore sealing often uses organic resins such as epoxy resins, there are also methods that apply a coating material containing an inorganic component and then volatilize the solvent to fill the pores with the inorganic component (see, for example, Patent Documents 1 and 2).

[0007] If the sealing component that fills the pores of the thermal spray coating, which serves as a protective layer, disappears, the interior of the dielectric layer may be exposed to the plasma gas, affecting the dielectric layer's properties. For example, cracks or wear in the dielectric layer could cause the dielectric layer to adhere to the semiconductor wafer, potentially reducing the semiconductor wafer yield or impairing the dielectric layer's own electrical properties, leading to poor adhesion.

[0008] [Prior art literature]

[0009] [Patent Document]

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 2004-190136

[0011] Patent Document 2: Japanese Patent Application Laid-Open No. 2004-260159 Summary of the Invention

[0012] [Problems to be solved by the invention]

[0013] Electrostatic chucks can be categorized into several types, such as Johnson-Rahbek force type and Coulomb force type, depending on the electrostatic adsorption mechanism. Depending on the type, it is sometimes impossible to form a highly corrosion-resistant dielectric layer on the electrostatic adsorption surface.

[0014] For example, a coating of yttrium oxide has a high volume resistivity and therefore cannot be used as a dielectric layer in a Johnson-Rabec force type electrostatic chuck in which a minute amount of current flows on the outermost surface.

[0015] One possible method for forming a highly corrosion-resistant dielectric layer on the electrostatically attracted surface of a Johnson-Labeck force electrostatic chuck is to use a spraying material with low volume resistivity and excellent corrosion resistance to form the dielectric layer by spraying. However, a spraying material capable of achieving this goal has not yet been found.

[0016] Another possible method is to form a ceramic spray coating using a spray material with poor corrosion resistance but low volume resistivity, followed by sealing with a highly corrosion-resistant sealing agent. This method can be expected to form a highly corrosion-resistant dielectric layer without significantly altering the electrical properties of the electrostatically attracted surface.

[0017] However, as in Patent Documents 1 and 2, if one wishes to seal the pores of a ceramic sprayed film using yttrium oxide by a sol-gel method, it is necessary to perform heat treatment at a high temperature (e.g., a temperature above 500°C) until the organic components disappear. As a result, due to the difference in thermal expansion between the ceramic sprayed film and the metal mounting table constituting the electrostatic chuck, large cracks may sometimes form in the ceramic sprayed film, and the ceramic sprayed film may no longer function as a dielectric layer.

[0018] In addition, the following method is also considered: after forming a ceramic sprayed film using a spraying material with poor corrosion resistance but low volume resistivity, instead of sealing the holes, a corrosion-resistant film of about several microns is formed by PVD or CVD to cover the entire surface of the ceramic sprayed film.

[0019] However, even in the case of the above method, due to the heat generated during the process by the PVD method or the CVD method, cracks may be generated in the ceramic sprayed film due to the difference in thermal expansion between the ceramic sprayed film and the metal mounting table constituting the electrostatic chuck.

[0020] As described above, it is difficult to form a dielectric layer having low volume resistivity and high corrosion resistance on the electrostatic adsorption surface of a Johnson-Rabec force type electrostatic chuck.

[0021] [Technical means to solve the problem]

[0022] The inventors conducted diligent research to solve the above-mentioned problems and found that by using a new sealing component, a Johnson-Rabec force type electrostatic chuck can be provided, which includes a layer with low volume resistivity and high corrosion resistance as a dielectric layer constituting the electrostatic adsorption surface, thereby completing the present invention.

[0023] (1) The electrostatic chuck of the present invention is a Johnson-Rabec force type electrostatic chuck having a metal substrate, an electrostatic adsorption electrode provided on the metal substrate via an insulating layer, and a dielectric layer constituting an electrostatic adsorption surface in contact with a workpiece.

[0024] The dielectric layer includes a ceramic spray coating and a sealing component filled in the pores of the ceramic spray coating.

[0025] The sealing component comprises a metal organic acid salt containing a rare earth element.

[0026] The electrostatic chuck includes a dielectric layer comprising a ceramic spray coating and a specific sealing component as a dielectric layer having an electrostatically attractive surface. The dielectric layer has low volume resistivity and high corrosion resistance. Therefore, the electrostatic chuck is a Johnson-Rabec force type electrostatic chuck with excellent corrosion resistance.

[0027] (2) The electrostatic chuck preferably has a volume resistivity of 1.0×10 8 Ω·cm~1.0×10 13 Ω·cm.

[0028] In this case, as a Johnson-Rabec force type electrostatic chuck, excellent electrostatic adsorption performance can be exhibited.

[0029] (3) In the electrostatic chuck, the ceramic sprayed film preferably includes aluminum-titanium oxide.

[0030] In this case, it is particularly suitable to set the volume resistivity to a value suitable for a Johnson-Rabec force type electrostatic chuck.

[0031] (4) In the electrostatic chuck, the rare earth element is preferably yttrium or ytterbium.

[0032] In these cases, it is particularly suitable to make the dielectric layer a layer with high corrosion resistance.

[0033] (5) The processing apparatus of the present invention includes the electrostatic chuck according to any one of (1) to (4).

[0034] Examples of the processing apparatus include a plasma processing apparatus, etc. In this case, the electrostatic chuck included in the plasma processing apparatus has excellent corrosion resistance (plasma resistance).

[0035] [Effects of the Invention]

[0036] According to the present invention, a Johnson-Rabec force type electrostatic chuck having an electrostatic adsorption surface excellent in corrosion resistance, and a processing apparatus including the electrostatic chuck can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a longitudinal sectional view showing a schematic structure of a plasma processing apparatus according to an embodiment of the present invention.

[0038] Figure 2 yes Figure 1 A longitudinal cross-sectional view of an electrostatic chuck included in a plasma processing apparatus.

[0039] Figure 3 This is a graph showing the measurement results of Test Example 1.

[0040] Figure 4 (a) is a diagram schematically showing an electrostatic chuck for evaluation produced in Test Example 2. Figure 4 (b) is a graph showing the cumulative discharge time until cracks occur.

[0041] Figure 5 (a) is an observation image of the cross section of area A after the exposure test. Figure 5 (b) is a diagram showing the distribution of each component in the film of the electrostatic chuck for evaluation.

[0042] Figure 6 (a) and Figure 6 (b) is a diagram showing the distribution of fluorine in the film of the electrostatic chuck for evaluation. Figure 6 (a) shows the analysis results of region A. Figure 6 (b) shows the analysis results of region B.

[0043] Figure 7 This is a graph showing the measurement results of Fourier transform-infrared spectroscopy (FT-IR) analysis performed in Test Example 3.

[0044] Figure 8 This is a chromatogram obtained in the gas chromatography-mass spectrometry (GC-MS) analysis performed in Experimental Example 3.

[0045] Figure 9 (a) and Figure 9 (b) is in Figure 8 The mass spectrum of a portion of the detection peak detected in the chromatogram of Figure 9 (c)~ Figure 9 (e) is the database search result.

[0046] Figure 10 This is a chromatogram obtained in the GC analysis performed in Experimental Example 3.

[0047] [Explanation of Symbols]

[0048] 10: Plasma treatment device

[0049] 11: Plasma formation part

[0050] 12: Vacuum container

[0051] 13: Exhaust system

[0052] 101: Microwave Source

[0053] 102: Automatic Matcher

[0054] 103: Waveguide

[0055] 104: Solenoid coil

[0056] 110: Plasma processing chamber

[0057] 111: Dielectric Window

[0058] 112: Shower Board

[0059] 113: Gas ring (gas inlet)

[0060] 120: Electrostatic chuck

[0061] 121: RF Power Supply

[0062] 122: Matcher

[0063] 130: Movable valve

[0064] 131: TMP

[0065] 140: Gas Source

[0066] 141: Mass Flow Controller

[0067] 142: Gas supply valve

[0068] 150: (Semiconductor) chip

[0069] 201: Metal substrate

[0070] 202: Insulation layer

[0071] 203: Heater (heater layer)

[0072] 204: Flow path (refrigerant tank)

[0073] 205: Suction cup electrode

[0074] 206: Dielectric layer

[0075] 207: Electrostatic adsorption surface

[0076] 220: Electrostatic chuck for evaluation. DETAILED DESCRIPTION

[0077] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0078] (First embodiment)

[0079] Here, an embodiment of the present invention will be described by taking a plasma processing apparatus as an example.

[0080] Figure 1 It is a longitudinal sectional view showing a schematic structure of a plasma processing apparatus according to this embodiment.

[0081] Figure 1 The processing apparatus shown is a plasma processing apparatus 10. The plasma processing apparatus 10 can be preferably used as a plasma etching apparatus, for example.

[0082] The plasma processing apparatus 10 is roughly divided into three parts, specifically, a plasma forming unit 11 , a vacuum container 12 , and an exhaust system 13 .

[0083] The plasma generation unit 11 comprises a microwave source 101, a waveguide 103, and a solenoid coil (a device generating a static magnetic field) 104. The microwave source 101 is grounded via a power supply, and the adjacent automatic matching unit 102 adjusts the load impedance, automatically suppressing reflected waves. The waveguide 103 changes its cross-section from a rectangular to a circular shape and transmits microwaves to a cylindrical cavity resonator 105. The solenoid coil 104 is positioned to cover the top and sides of the vacuum container 12. By varying the current flowing through the electromagnet, the distribution of the static magnetic field can be controlled.

[0084] The vacuum vessel 12 includes a dielectric window (microwave introduction window) 111, a shower plate 112, a gas ring (gas introduction portion) 113, and a plasma processing chamber 110. Within the vacuum vessel 12, a desired reactive gas, whose flow rate is controlled by a mass flow controller 141 and a gas supply valve 142, is introduced from a gas source 140 into the space between the dielectric window (microwave introduction window) 111 and the shower plate 112 via the gas ring (gas introduction portion) 113, and then supplied into the plasma processing chamber 110 via the shower plate 112.

[0085] The shower plate 112 is configured to have a plurality of holes at positions facing the semiconductor wafer 150 electrostatically attracted to the electrostatic chuck 120 , and can supply the processing gas from the gas source 140 into the vacuum chamber 12 .

[0086] The shower plate 112 is disposed facing the electrostatic chuck 120 with a gap therebetween.

[0087] The vacuum container 12 further includes an electrostatic chuck 120 at the lower portion within the plasma processing chamber 110 .

[0088] Electrostatic chuck 120 has a disc shape and can electrostatically attract and hold a semiconductor wafer (also referred to as a wafer in this specification) 150, serving as an object to be processed, or control the temperature of wafer 150. Furthermore, a radio frequency (RF) power supply 121 is connected to metal substrate 201 of electrostatic chuck 120 via a matching unit 122, so that electrostatic chuck 120 can apply RF to wafer 150.

[0089] The exhaust system 13 includes a movable valve 130 and a turbomolecular pump (TMP) 131. Gas in the plasma processing chamber 110 is exhausted from the TMP 131. The movable valve 130, located upstream of the TMP, controls the exhaust rate of the exhausted gas, thereby controlling the pressure in the plasma processing chamber 110.

[0090] Reference Figure 2 The structure of the electrostatic chuck 120 will be described in detail.

[0091] Figure 2 yes Figure 1 A longitudinal cross-sectional view of an electrostatic chuck included in the plasma processing apparatus 10.

[0092] The electrostatic chuck 120 includes a metal substrate 201 comprising metal, an insulating layer 202 disposed on the upper surface of the metal substrate 201 , a chuck electrode (electrode for electrostatic adsorption) 205 disposed on the insulating layer 202 , and a dielectric layer 206 disposed so as to cover the chuck electrode 205 .

[0093] The insulating layer 202 includes therein a heater (heater layer) 203. The heater 203 is heated by energizing a DC power supply for the heater (not shown).

[0094] The dielectric layer 206 has an electrostatic attraction surface 207 in contact with the wafer 150. The dielectric layer 206 is provided to cover the upper surface and side surfaces of the electrostatic chuck 120 and also functions as a protective layer for the electrostatic chuck 120.

[0095] Flow paths (coolant tanks) 204 are concentrically or spirally arranged inside electrostatic chuck 120 (metal substrate 201). Coolant whose temperature and flow rate (flow velocity) are regulated by a temperature regulating unit (not shown) is introduced into flow paths 204.

[0096] A heat transfer gas flow path (not shown) is provided between dielectric layer 206 of electrostatic chuck 120 and the back surface of wafer 150. The heat transfer gas flow path includes grooves formed on the surface of dielectric layer 206 and the semiconductor wafer, with the grooves functioning as a gas flow path. A heat transfer gas, such as He, is supplied to the heat transfer gas flow path from a heat transfer gas supply source.

[0097] The electrostatic chuck 120 generates a Johnson-Rabec force by applying a DC voltage (chuck voltage) to the chuck electrode 205 using a DC power supply (not shown), thereby adsorbing and holding the semiconductor wafer 150 on the electrostatic adsorption surface 207 of the electrostatic chuck 120 .

[0098] The metal substrate 201 includes, for example, titanium, aluminum, molybdenum, tungsten, an alloy containing at least one of these, etc. When an aluminum metal substrate is used, the surface may be subjected to alumite treatment, for example.

[0099] The insulating layer 202 includes, for example, aluminum oxide (Al2O3). The insulating layer 202 is, for example, a sprayed film formed by spraying. The insulating layer 202 may include one layer of the sprayed film or two or more layers of the sprayed film.

[0100] The dielectric layer 206 comprises a ceramic spray coating and a sealing component that fills the pores of the ceramic spray coating. The sealing component prevents atmospheric moisture or reaction products generated during etching from penetrating into the pores of the spray coating or into microcracks generated during surface polishing.

[0101] The sealing treatment for filling the pores of the ceramic sprayed film with the sealing component is performed, for example, by applying a sealing agent to the surface of the ceramic sprayed film, allowing it to be impregnated for a certain period of time, and then performing a heat treatment to volatilize the solvent component in the sealing agent.

[0102] The ceramic sprayed film constituting the dielectric layer 206 is, for example, a film containing aluminum-titanium oxide.

[0103] As the aluminum-titanium oxide, it is more preferred that the aluminum-titanium oxide contains 2.0 wt% to 12.0 wt% of titanium oxide, with the remainder being aluminum oxide.

[0104] The dielectric layer 206 may include one layer of sprayed film, or may include two or more layers of sprayed film.

[0105] The thickness of the insulating layer 202 is, for example, approximately 200 μm to 500 μm.

[0106] The thickness of the dielectric layer 206 is, for example, approximately 100 μm to 500 μm.

[0107] The volume resistivity of the ceramic spray coating constituting the dielectric layer 206 is preferably 1.0×10 8 Ω·cm~1.0×10 13 Ω·cm.

[0108] The above range is a volume resistivity suitable for electrostatic adsorption of the object to be processed by utilizing the Johnson-Rabec force.

[0109] If the volume resistivity is less than 1.0×10 8 Ω·cm, the amount of current flowing in the dielectric layer 206 becomes too much, making it difficult to exert the electrostatic adsorption performance based on the Johnson-Rabec force. In addition, if the volume resistivity exceeds 1.0×10 13 Ω·cm, the amount of current flowing in the dielectric layer 206 becomes too small, making it difficult to exhibit the electrostatic adsorption performance based on the Johnson-Rabec force.

[0110] The ceramic spray coating containing 2.0 wt% to 12.0 wt% of titanium oxide and the rest of aluminum oxide has a volume resistivity of 1.0×10 8 Ω·cm~1.0×10 11 Ω·cm, and thus suitable as the dielectric layer 206 of the Johnson-Rabec force type electrostatic chuck.

[0111] The sealing component includes a metal organic acid salt containing a rare earth element. The sealing component preferably includes a cured product of the metal organic acid salt and a resin. In this case, the resin acts as a binder to retain the metal organic acid salt.

[0112] This type of solidified material has excellent environmental barrier properties, preventing cleaning fluids or corrosive gases from penetrating into the interior of the ceramic spray-coated film. In addition, the solidified material contains a metal organic acid salt containing a rare earth element. When a plasma treatment device is used, the rare earth element is oxidized by the influence of oxygen plasma, etc. to form a rare earth oxide (yttrium oxide, etc.). Therefore, it is not easily degraded by plasma and can maintain a good sealing state for a long time. As a result, the corrosion of the suction cup electrode 205 or the metal substrate 201 can be suppressed, and the corrosion resistance is excellent.

[0113] Furthermore, the sealing treatment for filling the pores of the ceramic spray coating with the solidified material can be performed at a low temperature of 200° C. or lower.

[0114] Therefore, during the sealing process, cracks or the like may be avoided in the ceramic sprayed film due to the difference in thermal expansion between the metal substrate 201 and the ceramic sprayed film.

[0115] Furthermore, the solidified material has little influence on the volume resistivity of the ceramic sprayed film, and thus the electrical properties of the ceramic sprayed film suitable for electrostatically adsorbing the object to be processed by the Johnson-Rabec force can be maintained.

[0116] Among the metal organic acid salts containing rare earth elements, yttrium or ytterbium is preferred as the rare earth element because the oxides thereof have high corrosion resistance (plasma resistance).

[0117] Examples of the metal organic acid salt containing a rare earth element include salts of a carboxyl group-containing compound and a rare earth element-containing compound, and specific examples include yttrium 2-ethylhexanoate, yttrium octanoate, yttrium decanoate, yttrium stearate, and yttrium naphthenate.

[0118] As described above, from the viewpoint of improving the environmental barrier properties and corrosion resistance of the dielectric layer 206 , the sealing component preferably contains a cured product of a resin.

[0119] The resin can be either a natural resin or a synthetic resin. Terpenoids are preferred as natural resins. Among these, rosin primarily composed of diterpene carboxylic acids such as abietic acid and pimaric acid is preferred. This is because the hydroxyl groups contained in diterpene carboxylic acids have a high affinity for oxide ceramics, improving the adhesion between the ceramic spray coating and the sealing component, and providing excellent environmental barrier properties.

[0120] The content of the metal organic acid salt containing a rare earth element in the sealing component is preferably 20 wt% or greater. If the content of the metal organic acid salt is less than 20 wt%, rare earth oxides may not be fully formed. For better corrosion resistance, the content of the metal organic acid salt is more preferably 40 wt% or greater.

[0121] The content of the resin in the sealing component is preferably 10 wt% or more. If it is less than 10 wt%, sealing may be insufficient. More preferably, it is 40 wt% or more to obtain excellent environmental barrier properties.

[0122] The dielectric layer 206 of this structure can be formed by, for example, the following method.

[0123] (1) A thermal spraying material such as aluminum-titanium oxide is thermally sprayed onto the insulating layer 202 so as to cover the chuck electrode 205 , thereby forming a ceramic thermal spraying film containing metal oxide and having pores.

[0124] In this case, the spraying method is not particularly limited, and for example, plasma spraying, flame spraying, etc. can be used.

[0125] (2) Different from the above step (1), a metal organic acid salt containing the rare earth element is prepared, diluted in resin oil, and an organic solvent is further added to adjust the concentration so as to obtain an appropriate viscosity.

[0126] Here, examples of the organic solvent include acetate and the like.

[0127] Examples of the resin oil include turpentine oil and the like.

[0128] (3) The solution prepared in step (2) is applied to the ceramic sprayed film formed in step (1), and the solution is allowed to penetrate into the pores of the ceramic sprayed film.

[0129] (4) Thereafter, a heating treatment is performed at a heating temperature of 120° C. to 200° C., for example, to volatilize a part or all of the organic solvent and sinter the sealing agent.

[0130] By performing these steps, the pores of the ceramic spray coating are filled with a sealing component comprising a cured mixture of a metal organic acid salt containing a rare earth element and a resin containing rosin, thereby forming a dielectric layer 206 comprising the ceramic spray coating and the sealing component.

[0131] Next, a processing method using the plasma processing apparatus 10 will be described.

[0132] First, semiconductor wafer 150 is loaded into vacuum container 12 through a loading port (not shown), placed on electrostatic chuck 120, and the loading port is closed. Next, TMP 131 exhausts the gas in plasma processing chamber 110 while adjusting the exhaust speed through movable valve 130.

[0133] Thereafter, a DC voltage is applied from a DC power supply (not shown) to the suction cup electrode 205, causing the semiconductor chip 150 to be electrostatically adsorbed on the electrostatic adsorption surface 207 of the dielectric layer 206, and a processing gas is supplied from the gas source 140 into the plasma processing chamber 110 via the mass flow controller 141 and the gas supply valve 142.

[0134] The electric field oscillated by microwave source 101 and introduced into processing chamber 110 via waveguide 103, dielectric window 111, and shower plate 112 interacts with the magnetic field generated by magnetic field generating coil 104, dissociating the processing gas supplied into processing chamber 110 and generating plasma within processing chamber 110. The thus generated processing gas plasma is used to etch semiconductor wafer 150 held on electrostatic chuck 120.

[0135] At this time, the temperature of the semiconductor wafer 150 is controlled to a predetermined temperature using the heater layer 203 and the flow path 204 included in the electrostatic chuck 120 .

[0136] (Other embodiments)

[0137] In the first embodiment, the insulating layer 202 is formed of ceramic by thermal spraying. However, in the electrostatic chuck according to the embodiment of the present invention, the insulating layer may be formed from a sintered body. In this case, the insulating layer is fixed to the upper surface of the metal substrate via an adhesive layer containing an epoxy resin adhesive, a silicone resin adhesive, or the like.

[0138] In the electrostatic chuck according to the embodiment of the present invention, the heater layer and the flow path (refrigerant tank) are not essential and may be provided as needed.

[0139] The plasma method applicable to the plasma processing apparatus according to the embodiment of the present invention is not limited to the microwave electron cyclotron resonance (ECR) plasma method, and other plasma methods such as capacitively coupled plasma method and inductively coupled plasma method may also be applied.

[0140] The processing apparatus according to the embodiment of the present invention is not limited to a plasma etching apparatus, and may be another processing apparatus such as an ashing apparatus or a film forming apparatus.

[0141] In the embodiment of the present invention, the object to be processed is not limited to a semiconductor wafer, and may be, for example, a glass substrate for a liquid crystal display (LCD).

[0142] [Evaluation test]

[0143] The electrostatic adsorption surface of the electrostatic chuck according to the embodiment of the present invention has excellent corrosion resistance. To demonstrate this, the following evaluation test was conducted.

[0144] (Test Example 1)

[0145] In the test examples, test pieces subjected to various spraying and sealing treatments were formed and exposed to a plasma etching environment (hereinafter referred to as exposure tests). In the test examples, the change in strain before cracking due to bending deformation of the test pieces was evaluated.

[0146] (1) Test substrate

[0147] The test substrate was titanium (TP340), and a plurality of substrate sheets with dimensions of 16 mm in width×100 mm in length×4 mm in thickness were prepared from the substrate.

[0148] (2) Formation of spray coating and sealing treatment

[0149] A 0.3 mm thick ceramic spray coating was formed by spraying aluminum oxide-10 wt% titanium dioxide powder onto one side of each substrate sheet using atmospheric pressure plasma spraying. The ceramic spray coating was then subjected to various sealing treatments. The sealing treatments were performed using the following two methods (Sealing Treatment A and Sealing Treatment B).

[0150] Sealing Treatment A: A mixed solution containing 55 wt% turpentine, 15 wt% yttrium 2-ethylhexanoate, and 30 wt% acetate was applied to the surface of the ceramic spray coating and impregnated, followed by calcination at 150°C for 2 hours. This prepared a test piece (No. 1) in which the pores of the ceramic spray coating were filled with a sealing component containing yttrium 2-ethylhexanoate and a resin.

[0151] Sealing treatment B: A mixed solution containing 10 wt% monomethyl triisocyanate silane and 90 wt% acetate was applied to the surface of the ceramic spray coating and impregnated, followed by calcination at 70°C for 6 hours. In this manner, a test piece (No. 2) in which the pores of the ceramic spray coating were sealed with silicone resin was prepared.

[0152] In addition, a test piece (No. 3) was prepared in which a ceramic spray coating was formed but no sealing treatment was performed.

[0153] (3) Test methods and conditions

[0154] In order to examine changes in strain before and after cracking of the test pieces, the test pieces (No. 1 to No. 3) were exposed to the plasma etching environment for 200 hours under the following conditions.

[0155] <Plasma Etching Conditions>

[0156] Ar gas flow rate: 60ml / min

[0157] NF3 gas flow rate: 750ml / min

[0158] Pressure: 40Pa

[0159] Discharge output: 1000W

[0160] Next, a strain gauge was attached to the thermally sprayed surface of each test piece before and after the exposure test, and a bending deformation was applied at 90 degrees to measure the strain amount when cracking occurred.

[0161] (4) Test results

[0162] Figure 3 The test results are shown in . Figure 3 This is a graph showing the measurement results of Test Example 1. Figure 3 Each numerical value in the table represents a relative value based on the strain amount of the test piece (No. 2) before exposure.

[0163] After the test pieces (No. 2) and (No. 3) were exposed to the plasma etching environment, the strain amount before cracking was significantly reduced.

[0164] On the other hand, in the test piece (No. 1), after being exposed to the plasma etching environment, almost no change in the strain amount before cracking was observed.

[0165] Therefore, it was confirmed that the ceramic thermal spray coating in which the pores were filled with a sealing component containing yttrium 2-ethylhexanoate and a resin was suitable for suppressing cracks compared with other specifications.

[0166] (Test Example 2)

[0167] In the test example, various spraying and sealing treatments were performed to form Figure 2An electrostatic chuck for evaluation of the structure shown was then exposed to a plasma etching environment and subjected to an exposure test. (a) The cumulative discharge time until cracks occurred in the sprayed coating was measured, (b) Cross-sectional X-ray photoelectron spectroscopy (XPS) analysis after the exposure test was performed, and (c) Electron probe microanalysis (EPMA) analysis after the exposure test was performed.

[0168] (1) Test substrate

[0169] In this test example, the test substrate was titanium (TP340).

[0170] (2) Formation of spray coating and sealing treatment

[0171] In this test example, aluminum oxide powder was sprayed onto the base sheet as a first insulating layer using atmospheric pressure plasma spraying to form a ceramic sprayed film.

[0172] Next, as a heater layer, tungsten powder was sprayed onto the first insulating layer using an atmospheric pressure plasma spraying method to form a tungsten sprayed film.

[0173] Next, as a second insulating layer, aluminum oxide powder was sprayed onto the heater layer and the first insulating layer using atmospheric pressure plasma spraying to form a ceramic sprayed film.

[0174] Next, as a chuck electrode layer, tungsten powder was sprayed onto the second insulating layer using an atmospheric pressure plasma spraying method to form a tungsten sprayed film.

[0175] Next, as a dielectric layer, aluminum oxide-10 wt% titanium dioxide powder was sprayed by atmospheric pressure plasma spraying to form a ceramic spray coating.

[0176] Next, various sealing treatments performed in Experimental Example 1 were applied separately to the dielectric layer by region.

[0177] After this treatment, the electrostatic chuck 220 for evaluation is manufactured (refer to Figure 4 (a)).

[0178] The evaluation electrostatic chuck 220 has an electrostatic adsorption surface of a dielectric layer having a region A sealed in the same manner as the test piece (No. 1) of Test Example 1 and a region B sealed in the same manner as the test piece (No. 2) of Test Example 1.

[0179] (3) Exposure test method

[0180] The evaluation electrostatic chuck 220 was exposed to a plasma etching environment under the following conditions: The heater layer of the evaluation electrostatic chuck 220 was connected to a DC power supply for heaters (not shown) and energized repeatedly.

[0181] <Plasma Etching Conditions>

[0182] Ar gas flow rate: 60ml / min

[0183] NF3 gas flow rate: 750ml / min

[0184] Pressure: 40Pa

[0185] Discharge output: 1000W

[0186] Heater output: 1200W

[0187] (a) Cumulative discharge time before cracking

[0188] The measurement results of the cumulative discharge time are shown in Figure 4 (a) and Figure 4 (b).

[0189] Figure 4 (a) is a diagram schematically showing an electrostatic chuck 220 for evaluation produced in Experimental Example 2. Figure 4 (b) is a graph showing the cumulative discharge time until cracking was generated, measured in Test Example 2.

[0190] like Figure 4 As shown in (b), in region A, no cracks were generated even during 1000 hours of discharge, but in region B, cracks were generated during 180 hours of discharge.

[0191] (b) Cross-section XPS analysis results

[0192] After the exposure test, a portion of the evaluation electrostatic chuck was cut off and the cross-section of the ceramic spray coating was analyzed by XPS. Figure 5 (a) and Figure 5 (b).

[0193] Figure 5 (a) is an observation image of the cross section of area A after the exposure test. Figure 5 (b) is a graph showing the distribution of each component in the film of the electrostatic chuck for evaluation measured in Test Example 2.

[0194] As an XPS analysis apparatus, Quantera SXM manufactured by PHI was used.

[0195] like Figure 5(a) and Figure 5 As shown in (b), it is confirmed that the amount of fluorine in region A is smaller than that in region B.

[0196] (c) Cross-section EPMA analysis results

[0197] After the exposure test, a portion of the evaluation electrostatic chuck was cut off and EPMA analysis of the cross section near the surface of the ceramic spray coating was performed. The results are shown in FIG. Figure 6 (a) and Figure 6 (b).

[0198] Figure 6 (a) and Figure 6 (b) is a diagram showing the distribution of fluorine in the film of the electrostatic chuck for evaluation measured in Test Example 2. Figure 6 (a) shows the analysis results of region A. Figure 6 (b) shows the analysis results of region B. Figure 6 (a) and Figure 6 (b) are all colored images.

[0199] As an EPMA analysis apparatus, JXA-8500F manufactured by JEOL Ltd. was used.

[0200] like Figure 6 (a) and Figure 6 As shown in (b), it was confirmed that the amount of fluorine in region A was smaller than that in region B, and the range of fluorine penetration from the surface was also narrow.

[0201] (Test Example 3)

[0202] In Test Example 3, the sealing components contained in the thermal spray coating of the test piece (No. 1) prepared in Test Example 1 were analyzed.

[0203] First, the same sealing agent as that used in Test Example 1 was placed in a crucible and calcined at 150° C. for 2 hours to solidify.

[0204] Next, the obtained cured product was subjected to FT-IR analysis.

[0205] For FT-IR analysis, a Fourier transform infrared spectrometer model 3100 manufactured by Agilent Technologies was used.

[0206] Figure 7 It is an infrared (IR) spectrum obtained by FT-IR analysis.

[0207] The FT-IR analysis confirmed that yttrium 2-ethylhexanoate was contained in the cured product.

[0208] Next, the solidified product obtained by calcining at 150° C. for 2 hours was subjected to GC-MS analysis.

[0209] GC-MS analysis was performed using a gas chromatograph mass analyzer 5977A MSD manufactured by Agilent Technologies, Inc. As a derivatization treatment, the solidified product was dissolved by heating in a sealed container at 80°C (for 18.5 hours) with a 5 wt% solution of hydrochloric acid in methanol, and then methyl esterification was performed.

[0210] Figure 8 This is a chromatogram obtained by GC-MS analysis.

[0211] Figure 9 (a) and Figure 9 (b) is in Figure 8 The mass spectrum of a portion of the detection peaks (peak 3 and peak 4) detected in the chromatogram of Figure 9 (c)~ Figure 9 (e) is the database search result.

[0212] The GC-MS analysis confirmed that the solidified material contained 2-ethylhexanoic acid and a rosinic acid-like compound derived from turpentine oil.

[0213] Furthermore, the sample (cured product) was subjected to GC analysis using GC2010 manufactured by Shimadzu Corporation.

[0214] Here, the column used was DB-17 manufactured by Agilent Technologies, Inc. As a derivatization treatment, the solidified product was dissolved by heating it in a sealed container at 80° C. (for 18.5 hours) using a 5 wt % solution of hydrochloric acid in methanol, and then methyl esterification was performed.

[0215] Figure 10 This is a chromatogram obtained by GC analysis.

[0216] The GC analysis confirmed that the cured product contained 41 wt% of 2-ethylhexanoic acid.

[0217] Next, the solidified material was subjected to inductively coupled plasma (ICP) analysis.

[0218] ICP analysis was performed using ICP AES5110VDV manufactured by Agilent Technologies.

[0219] As a result, 13 wt% of Y was detected.

[0220] From the above, it was confirmed that the composition of the cured product was about 54 wt % of yttrium 2-ethylhexanoate, and the remainder was rosin-based substances mainly composed of a rosinic acid-like compound.

Claims

1. An electrostatic chuck of the Johnson-Rabec force type, comprising a metal substrate, an electrostatic adsorption electrode disposed on the metal substrate via an insulating layer, and a dielectric layer constituting an electrostatic adsorption surface in contact with an object to be processed, wherein: The dielectric layer includes a ceramic spray coating and a sealing component filled in the pores of the ceramic spray coating. The sealing component comprises a metal organic acid salt containing a rare earth element, The volume resistivity of the ceramic sprayed film is 1.0×10 8 Ω·cm~1.0×10 13 Ω·cm. 2 . The electrostatic chuck according to claim 1 , wherein the dielectric layer has a thickness of 100 μm to 500 μm. 3 . The electrostatic chuck according to claim 1 , wherein the ceramic sprayed film comprises aluminum-titanium oxide.

4. The electrostatic chuck according to claim 2, wherein the ceramic sprayed film comprises aluminum-titanium oxide. 5 . The electrostatic chuck according to claim 1 , wherein the rare earth element is yttrium or ytterbium.

6. A processing device comprising the electrostatic chuck according to any one of claims 1 to 5.

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