Electrostatic chuck device, method for manufacturing base, and method for manufacturing electrostatic chuck device

Abstract

This electrostatic chuck device comprises an electrostatic chuck member having a dielectric substrate and an internal electrode, a base, and a bonding layer for bonding the electrostatic chuck member and the base. The base includes a highly thermoconductive material and a first electroconductive material. The dielectric substrate is made of a ceramic including an insulating material and a second electroconductive material. The bonding layer includes an insulating material and at least one from among the highly thermoconductive material and the first electroconductive material.

Description

Electrostatic chuck device, base manufacturing method, and electrostatic chuck device manufacturing method

[0001] The present invention relates to an electrostatic chuck device, a method for manufacturing a base, and a method for manufacturing an electrostatic chuck device. This application claims priority to Japanese Patent Application No. 2024-054429, filed March 28, 2024, the contents of which are incorporated herein by reference.

[0002] In a semiconductor manufacturing process for manufacturing semiconductors such as ICs, LSIs, and VLSIs, an electrostatic chuck device has been used to electrostatically attract a plate-like sample such as a silicon wafer when performing plasma processing on the plate-like sample. The electrostatic chuck device includes an electrostatic chuck member and a metal base that are laminated together with a bonding layer interposed therebetween. A resin adhesive is generally used to form the bonding layer (see, for example, Patent Document 1).

[0003] In recent years, with the diversification of semiconductor processes, the temperature of plate-shaped samples being processed has come to be controlled over a wider temperature range than in the past. However, the above-mentioned resin adhesive has lower thermal conductivity than a metal base. Therefore, when controlling the temperature of a wafer over a wide temperature range, in an electrostatic chuck device in which the electrostatic chuck member and the base are bonded together with a resin adhesive, heat transfer between the electrostatic chuck member and the base is hindered, making stable temperature control difficult.

[0004] To solve this problem, Patent Document 2 proposes an electrostatic chuck device in which a bonding layer that bonds an electrostatic chuck member to a metal base is bonded with an inorganic bonding material such as a metal material. In this type of electrostatic chuck device, it is thought that the bonding layer is less likely to inhibit heat transfer, and stable temperature control is expected.

[0005] JP 2022-133003 A JP 2023-1603 A

[0006] However, when an electrostatic chuck member made of ceramics is brazed to a metal base using a metallic material, cracks may occur in the electrostatic chuck member during brazing. Therefore, there has been a need for a new electrostatic chuck device that enables stable wafer temperature control when the electrostatic chuck member and the base are joined using an inorganic material.

[0007] 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 device that enables stable wafer temperature control, and a further object of the present invention is to provide a novel method for manufacturing a base and a novel method for manufacturing an electrostatic chuck device that enable stable wafer temperature control.

[0008] The inventors have conducted research and found that by forming the base from conductive ceramics made from a highly thermally conductive material and a conductive material, it is possible to obtain an excellent electrostatic chuck device in which the electrostatic chuck member and the base are joined together with an inorganic material. Based on this finding, the inventors have conducted further intensive research and have completed the present invention.

[0009] The present invention provides the following first aspect: [1] An electrostatic chuck device comprising: an electrostatic chuck member having a dielectric substrate and an internal electrode, a base, and a bonding layer bonding the electrostatic chuck member to the base, wherein the base includes a highly thermally conductive material and a first conductive material, the dielectric substrate is made of ceramics including an insulating material and a second conductive material, and the bonding layer includes the insulating material and at least one of the highly thermally conductive material and the first conductive material.

[0010] The first aspect of the present invention preferably has the following features [2] to [4]: ​​[2] The highly thermally conductive material is AlN, SiC, GaN, 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 the first conductive material and the second conductive material are at least one selected from the group consisting of C, carbon, aluminum, copper, silver, and gold, and the first conductive material and the second conductive material are at least one selected from the group consisting of SiC, TiO ２ , TiN, TiC, W, WC, Mo, MoC, Mo ２ [1] The electrostatic chuck device according to [1], wherein the material is at least one selected from the group consisting of C, TaC, TaN, NbC, VC, and C.

[0011] [3] The electrostatic chuck device according to [2], wherein the highly thermally conductive material is AlN and the first conductive material is TiN.

[0012] [4] The electrostatic chuck device according to any one of [1] to [3], wherein the base is made of a single composition.

[0013] The present invention provides the following second aspect: [5] A method for manufacturing a base, comprising the steps of: forming a continuous groove portion in a band shape in a plan view on one surface of at least one of a pair of conductive ceramic plates; and overlapping and bonding the pair of conductive ceramic plates with the groove portion facing the other conductive ceramic plate, wherein the conductive ceramic plate contains a highly thermally conductive material and a first conductive material, and a space surrounded by the groove portion and the other conductive ceramic plate is a flow path through which a refrigerant flows.

[0014] The present invention provides the following third aspect: [6] A method for manufacturing a base, comprising: forming a continuous through hole in a band shape in a plan view from one surface of a substrate; and sandwiching and bonding the substrate between a pair of conductive ceramic plates, wherein the substrate and the pair of conductive ceramic plates each contain a highly thermally conductive material and a first conductive material, and a space surrounded by the through hole and the pair of conductive ceramic plates is a flow path through which a coolant flows.

[0015] The second and third aspects of the present invention preferably include the feature of [7] below: [7] A method for manufacturing an electrostatic chuck device, comprising: a step of overlapping and bonding a base manufactured by the method for manufacturing a base according to [5] or [6] and an electrostatic chuck member having a dielectric substrate and an internal electrode via a bonding material, wherein the dielectric substrate is made of ceramics containing an insulating material and a second conductive material, and the bonding material contains the insulating material and at least one of the high thermal conductivity material and the first conductive material.

[0016] The present invention provides a fourth aspect as follows: [8] A method for manufacturing an electrostatic chuck device, comprising the steps of: forming a continuous groove portion in a band shape in a plan view on one surface of a conductive ceramic plate; and superimposing and bonding an electrostatic chuck member having a dielectric substrate and an internal electrode on one surface of the conductive ceramic plate via a bonding material, wherein the conductive ceramic plate includes a high thermal conductivity material and a first conductive material, the dielectric substrate is made of ceramics including an insulating material and a second conductive material, a space surrounded by the groove portion and the electrostatic chuck member is a flow path through which a coolant flows, and the bonding material includes the insulating material and at least one of the high thermal conductivity material and the first conductive material.

[0017] According to the present invention, it is possible to provide a novel electrostatic chuck device that enables stable wafer temperature control, and also to provide a novel base manufacturing method and electrostatic chuck device manufacturing method that enable stable wafer temperature control.

[0018] Fig. 1 is a cross-sectional schematic view showing a preferred example of an electrostatic chuck device 1A according to the first embodiment. Fig. 2 is an explanatory view showing an example of a method for manufacturing a base 3. Fig. 3 is an explanatory view showing an example of a method for manufacturing a base 3. Fig. 4 is an explanatory view showing an example of a method for manufacturing a base 3. Fig. 5 is an explanatory view showing a preferred example of an electrostatic chuck device 1B according to a second embodiment. Fig. 6 is a scanning electron microscope (SEM) image of a conductive ceramic plate used in the examples.

[0019] [First Embodiment] A preferred example of an electrostatic chuck device according to a first embodiment of the present invention will be described below with reference to FIG. 1. In all of the following drawings, the dimensions and proportions of the components have been appropriately changed to make the drawings easier to understand. The following description is provided for specific purposes to better understand the gist 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, amount, type, position, and proportion may be changed, added, or omitted as necessary.

[0020] 1 is a schematic cross-sectional view showing a preferred example of an electrostatic chuck device 1A according to a first embodiment. The electrostatic chuck device 1A includes an electrostatic chuck member 2, a base 3, a bonding layer 4, a support plate 5, an insulator (insertion component) 23, and a power supply terminal 16. The electrostatic chuck member 2 and the base 3 are stacked on top of each other with the bonding layer 4 interposed therebetween.

[0021] In this specification, the direction in which the electrostatic chuck member 2 and the base 3 are stacked is referred to as the stacking direction. Furthermore, the side on which the electrostatic chuck member 2 is disposed with respect to the base 3 may be referred to as "one side in the stacking direction," and the opposite side may be referred to as "the other side in the stacking direction." In the following description, each part of the electrostatic chuck device 1A will be described assuming that the vertical direction is the stacking direction. However, the vertical direction here is used merely for the sake of simplicity of description and does not limit the position of the electrostatic chuck device 1A during use. The upper side corresponds to one side in the stacking direction, and the lower side corresponds to the other side in the stacking direction.

[0022] <Electrostatic Chuck Member> The electrostatic chuck member 2 has a dielectric substrate 11 and an attraction electrode 13 located inside the dielectric substrate 11. A mounting surface 2 a for attracting and holding a wafer W is provided on the upper surface of the electrostatic chuck member 2. A focus ring surrounding the wafer W may be disposed outside the mounting surface 2 a of the electrostatic chuck member 2.

[0023] (Dielectric Substrate) The dielectric substrate 11 is made of ceramics that contains an insulating material and a conductive material (second conductive material), has sufficient mechanical strength, and is resistant to corrosive gases and their plasma.

[0024] The ceramics constituting the dielectric substrate 11 are mainly composed of insulating material, such as aluminum oxide (Al ２ O ３ The term "main component" refers to a material that accounts for 50% or more by volume of the total. If necessary, the material may account for 55% or more by volume, 60% or more by volume, 80% or more by volume, 90% or more by volume, or 95% or more by volume of the total.

[0025] The second conductive material is not particularly limited as long as it is a material that can be used for the dielectric substrate 11, and examples thereof include SiC and TiO. ２ , TiN, TiC, W, WC, Mo, MoC, Mo ２ At least one selected from the group consisting of C, TaC, TaN, NbC, VC and C can be used.

[0026] The ceramics constituting the dielectric substrate 11 are selected as needed, but aluminum oxide (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 plate shape in a plan view. The dielectric substrate 11 has a mounting surface 2a on which the wafer W is mounted and a back surface 2b facing the opposite side of the mounting surface 2a. The mounting surface 2a may have, for example, a plurality of protrusions (not shown) formed at predetermined intervals. In this case, the mounting surface 2a supports the wafer W at the tips of the plurality of protrusions. In this specification, the term "plan view" refers to a field of view seen from the thickness direction of the electrostatic chuck member 2.

[0028] (Attraction Electrode) The attraction electrode 13 is disposed inside the dielectric substrate 11. The attraction electrode 13 extends in a plate shape along the mounting surface 2 a of the dielectric substrate 11. When a voltage is applied to the attraction electrode 13, the attraction electrode 13 generates an electrostatic attraction force that holds the wafer W on the mounting surface 2 a of the dielectric substrate 11. A power supply terminal 16 for applying a DC voltage to the attraction electrode 13 is connected to the attraction electrode 13.

[0029] The chucking electrode 13 is made of a composite of an insulating material and a conductive material. The insulating material contained in the chucking electrode 13 is not particularly limited, but may be, for example, aluminum oxide (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:

[0030] The conductive material contained in the attraction electrode 13 is molybdenum carbide (Mo ２ It is preferable that the material is at least one selected from the group consisting of molybdenum (Mo), tungsten carbide (WC), tungsten (W), tantalum carbide (TaC), tantalum (Ta), silicon carbide (SiC), carbon black, carbon nanotubes, and carbon nanofibers.

[0031] The thickness of the electrostatic chuck member 2 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 object, during plasma processing.

[0032] <Base> The base 3 is a disk-shaped member in a plan view, and supports the electrostatic chuck member 2 from below (the other side in the stacking direction). The base 3 is provided with a support surface 3a facing upward (one side in the stacking direction) and a lower surface 3b facing downward. The support surface 3a faces the back surface 2b of the dielectric substrate 11 in the vertical direction (stacking direction) via the bonding layer 4. The base 3 supports the electrostatic chuck member 2 on the support surface 3a.

[0033] A flow path 3f for circulating a coolant is provided inside the base 3. The coolant flowing through the flow path 3f can be selected arbitrarily, and may be water, He gas, N ２ A gas or the like is employed. The flow path 3f extends along the support surface 3a. The refrigerant in the flow path 3f cools the entire base 3 and also cools the electrostatic chuck member 2 via the support surface 3a. The base 3 is connected to an external high-frequency power supply 22 via a matching box (not shown), and also serves as an internal electrode for generating plasma.

[0034] The base 3 is made of a conductive ceramic (hereinafter sometimes abbreviated as "conductive ceramic") containing a highly thermally conductive material and a conductive material (first conductive material). Specifically, when the entire base 3 is taken as 100% by volume, the material of the base 3 preferably has a volume ratio of the highly thermally conductive material to the first conductive material of 30:70 to 60:40. The volume ratio may be 35:65 to 55:45, 40:60 to 50:50, or the like, as needed.

[0035] By using a conductive ceramic material for the base 3, heat is easily transferred from the electrostatic chuck member 2, and an electrostatic chuck device can be obtained that facilitates temperature control of the wafer W supported by the electrostatic chuck member 2.

[0036] The material forming the base must have excellent thermal conductivity, electrical conductivity, and workability, so it has traditionally been made of metals such as aluminum. Meanwhile, the dielectric substrate that forms the electrostatic chuck member is made of ceramics. Generally, 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 metal base and the electrostatic chuck member made of ceramics.

[0037] On the other hand, the base 3 employed in the electrostatic chuck device 1A of this embodiment is made of a conductive ceramic material. Such a base 3 easily transfers heat from the electrostatic chuck member 2, thereby providing an electrostatic chuck device that easily controls the temperature of the wafer W. The fact that the base 3 made of a conductive ceramic material easily transfers heat has been confirmed by simulation (described below).

[0038] 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 60 W / m·K to 100 W / m·K, or 70 W / m·K to 90 W / m·K, for example. Having a thermal conductivity within the above range allows input heat to be effectively dissipated.

[0039] The first conductive material is SiC or TiO ２ , TiN, TiC, W, WC, Mo, MoC, Mo ２Preferably, the first 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. The first conductive material and the second conductive material may be the same or different.

[0040] High thermal conductivity materials include AlN, SiC, GaN, and SiO ２ , Al ２ O ３ , SmAlO ３ , Si ３ N ４ , Al(OH) ３ , MgO, Mg(OH)2, BN, ZnO, BeO, B ４ Preferably, the first conductive material is at least one selected from the group consisting of C, carbon (C), aluminum, copper, silver, and gold. When SiC is used as the highly thermally conductive material, a material other than SiC is selected as the first conductive material. When SiC is used as the highly thermally conductive material, TiN, for example, can be selected as the first conductive material.

[0041] When the main component of the dielectric substrate 11 is aluminum oxide and is combined with silicon carbide, the thermal expansion coefficient of the dielectric substrate 11 is approximately equal to the thermal expansion coefficient of aluminum oxide (7.0 to 7.7 × 10 －６ / K) and the thermal expansion coefficient of silicon carbide (4.0 × 10 －６ / K). It is advisable to select a highly thermally conductive 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 first conductive material to be combined. For example, when a material with a thermal expansion coefficient larger than that of aluminum oxide is used as the first conductive material, the highly thermally conductive material to be combined should be a material with a relatively smaller thermal expansion coefficient than that of aluminum oxide, for example, AlN (thermal expansion coefficient 4.5×10 －６ / K) is preferred.

[0042] The base 3 is made of AlN (thermal expansion coefficient 4.5×10 －６ / K) and TiN (thermal expansion coefficient 9.35×10 －６ / K), that is, an AlN-TiN composite sintered body, is preferably used as the forming material.－６ / K) and TiN (thermal expansion coefficient 9.35×10 －６ It is also preferable to use a conductive ceramic formed from SiC—TiN (TiN—CuNb / K), that is, a SiC—TiN composite sintered body, as the forming material.

[0043] The thermal expansion coefficient of the base 3 is 6.0×10 －６ / K or more 9.0×10 －６ / K or less. －６ / K or more 8.5×10 －６ / K or less, 7.0 x 10 －６ / K or more 8.0×10 －６ When the thermal expansion coefficient of the base 3 is within the above range, the difference in thermal expansion with the dielectric substrate 11 containing mainly aluminum oxide can be easily reduced, and even when heated in the plasma process, internal stress is small, making it difficult for damage such as interfacial peeling to occur in the bonding layer.

[0044] It was confirmed by simulation that the base 3 having the above-described configuration can transfer heat input to the dielectric substrate 11 and dissipate it effectively.

[0045] In the simulation, the dielectric substrate 11 is Al ２ O ３ The heat transfer effect of the base 3 was confirmed for an electrostatic chuck device A in which the base 3 was made of AlN-TiN composite sintered body and aluminum, and an electrostatic chuck device B in which the base 3 was made of AlN-TiN composite sintered body. The bonding layer 4 was made of a metal brazing material.

[0046] As a result, when the temperature of the bonding layer 4 in the electrostatic chuck device A was T° C., the temperature of the bonding layer 4 in the electrostatic chuck device B was T−50° C. Furthermore, the temperatures of the dielectric substrate 11, the wafer W, and the contact portion between the wafer W and the dielectric substrate 11 were also 50° C. lower in the electrostatic chuck device B than in the electrostatic chuck device A. In other words, it was confirmed that by changing the material forming the base 3 from the conventional metal to a conductive ceramic, it is possible to effectively release (remove) plasma heat.

[0047] The base 3 may contain a sintering aid as long as it does not impair the effects of the present invention. The sintering aid is not particularly limited as long as it is a commonly added sintering aid. ２ O ３ , MgO, SiO ２ , CaO, La ２ O ３ , Ce ２ O ３ Among these, Y ２ O ３ , MgO, SiO ２ is preferred.

[0048] The volume resistivity of the base 3 is 1.0×10 －６ Ω・cm or more 1.0×10 －３ It is preferable that the resistivity is 5.0×10 Ω cm or less. －６ Ω・cm or more 5.0×10 －４ Ω・cm or less or 1.0×10 －５ Ω・cm or more 1.0×10 －４ The volume resistivity of the base 3 within the above range can provide sufficient conductivity.

[0049] The thermal expansion coefficient of the base 3 is preferably equal to that of the dielectric substrate 11. The absolute value of the difference between the thermal expansion coefficient of the base 3 and the thermal expansion coefficient of the dielectric substrate 11 is preferably 2.0 or less, more preferably 1.5 or less, even more preferably 1.3 or less, and even more preferably 1.0 or less.

[0050] The surface of the base 3 is preferably anodized to improve plasma resistance.

[0051] A hole 17 is provided in the base 3. The hole 17 extends in the vertical direction. The hole 17 penetrates the base 3 in the vertical direction and opens to the support surface 3a and the lower surface 3b of the base 3. The hole 17 is, for example, circular in plan view. An insulator 23, which will be described later, is inserted into the hole 17. Although FIG. 1 shows the hole 17 as penetrating the base 3 in the vertical direction, the hole 17 does not necessarily have to penetrate the base 3 as long as it opens to at least the support surface 3a and an insulator 23 is inserted therein.

[0052] (Method for Manufacturing Conductive Ceramic Plate) The conductive ceramic plate, which is the material of the base 3, can be obtained by mixing a high thermal conductivity material and a first conductive material in a predetermined range to obtain a raw material powder, and then using the obtained raw material powder to manufacture ceramics by a known method. For example, the conductive ceramic plate can be manufactured by the following steps: mixing the high thermal conductivity material and the first conductive material in a volume ratio of 30:70 to 60:40 to obtain a raw material powder; applying pressure to the obtained raw material powder to obtain a molded body; and pressure-sintering the obtained molded body to obtain a conductive ceramic. The volume ratio may be 35:65 to 550:45, or 40:60 to 50:50, for example.

[0053] The average primary particle size of the highly thermally conductive material is not particularly limited as long as a conductive ceramic is obtained, and for example, a highly thermally conductive material of 0.5 μm to 5 μm can be used. The average primary particle size of the first conductive material is not particularly limited as long as a conductive ceramic is obtained, and for example, a first conductive material of 0.5 μm to 5 μm can be used. The average primary particle size may be 0.7 μm to 4.5 μm, 1.0 μm to 4.0 μm, 1.5 μm to 3.5 μm, or 2.0 μm to 3.0 μm, respectively.

[0054] In the mixing step, the mixing method is not particularly limited as long as it is possible to mix the high thermal conductivity material and the first conductive material to obtain a raw material powder, and it is preferable to mix the high thermal conductivity material and the first conductive material using a mixing device such as a disperser, with an appropriate dispersant or solvent added to prevent aggregation of the high thermal conductivity material and the first conductive material. The mixing device is not particularly limited, and general devices such as a ball mill, planetary mill, bead mill, and atomizer can be used.

[0055] A drying step may be carried out after the mixing step. The drying method may be natural drying, a dryer, or spray drying to form granules, for example, granules of about 30 to 100 μm, from the raw material powder.

[0056] After the mixing step or the drying step, the raw material powder may be heated at 300° C. or higher and 600° C. or lower in a non-oxidizing atmosphere to remove impurities such as moisture, solvents, and dispersants contained in the raw material powder.

[0057] The non-oxidizing atmosphere is preferably an inert gas atmosphere using nitrogen or argon. When the heating is performed under an inert gas atmosphere, it is preferable to perform the heating treatment under a gas flow, in other words, a gas flow, in order to efficiently discharge generated impurities out of the system.

[0058] In the molding step, the obtained raw material powder is molded by applying pressure, preferably uniaxial molding (uniaxial press molding), using a mold molding method or the like depending on the shape of the desired conductive ceramic, to obtain a molded body of the desired shape.

[0059] In the pressure sintering step, the compact obtained in the molding step is subjected to pressure sintering by heating to 1600°C or higher while compacting under a vacuum or a non-oxidizing atmosphere at a pressure of 5 MPa or higher. This procedure promotes sintering of the high thermal conductivity material and the first conductive material contained in the compact, resulting in a dense sintered body with few pores. The temperature can be selected as needed, and may be 1600 to 1900°C or 1650 to 1800°C, for example. The heating time can be selected as needed, and may be, for example, 1 to 5 hours, 3 to 8 hours, or 6 to 12 hours.

[0060] A conductive ceramic plate can be obtained by the above steps, and the obtained conductive ceramic can be processed to obtain the base 3.

[0061] (Method for Manufacturing Base) The base 3 is obtained by processing the conductive ceramic plate obtained by the method described above into the shape of the base 3. Figures 2 to 4 are explanatory views showing an example of a preferred method for manufacturing the base 3. The example will be described below.

[0062] 2, two conductive ceramic plates are prepared, and a continuous groove 30x having a band-like shape in a plan view is formed on one surface 30a of at least one of the pair of conductive ceramic plates 30 (groove forming step). The groove 30x can be formed by a known method, such as die-sinking electrical discharge machining or copying machining.

[0063] The "pair of conductive ceramic plates" may be the same or different.

[0064] The grooves 30x may be uniformly of the same depth, or may have different depths as shown in FIG.

[0065] Next, the pair of conductive ceramic plates 30, 31 are overlapped and bonded together with the groove 30x facing the other conductive ceramic plate 31. Any common bonding method can be used as long as it does not impede the object of the present invention. From the viewpoint of more stable temperature control of the wafer, diffusion bonding is preferred. The space surrounded by the groove 30x and the opposing surface 31a of the conductive ceramic plate 31 becomes a flow path 3f (see FIG. 1 ) through which a refrigerant flows.

[0066] 3, grooves 30x and 31x may be provided in both of the pair of conductive ceramic plates 30 and 31. When grooves are provided in both of the pair of conductive ceramic plates, the shapes of the two grooves 30x and 31x in plan view are mirror images that overlap in plan when the grooves are placed opposite each other.

[0067] The depths of the grooves 30x and 31x may be the same or different.

[0068] Next, the pair of conductive ceramic plates 30, 31 are overlapped and bonded together with the groove 30x facing the other conductive ceramic plate 31. Any common bonding method can be used as long as it does not impede the object of the present invention. From the viewpoint of more stable temperature control of the wafer, diffusion bonding is preferred.

[0069] When grooves are provided on both of a pair of conductive ceramic plates, the grooves 30x and 31x are placed opposite each other and overlapped in a planar manner in the process of bonding them by diffusion, etc. That is, the conductive ceramic plate 30 is bonded to the conductive ceramic plate 31 by bringing the areas where the grooves 30x are not formed into contact with the areas where the grooves 31x are not formed into contact with each other.

[0070] 4, three conductive ceramic plates are first prepared, and through-holes 35x are formed in one surface of one of the plates (substrate) 35, forming continuous, band-like through-holes 35x in a plan view (through-hole forming step). The through-holes 35x can be formed by any method, for example, by known wire electric discharge machining.

[0071] Next, the substrate 35 is sandwiched between the remaining two conductive ceramic plates 36 and 37 and bonded by diffusion bonding or the like. The space surrounded by the through hole 35x and the opposing surfaces 36a and 37a of the conductive ceramic plates 36 and 37 becomes a flow path 3f (see FIG. 1) through which the refrigerant flows.

[0072] In this way, the base 3 can be manufactured. By using the same composition for the conductive ceramic plates 31 and 32, or the substrate 35 and the conductive ceramic plates 36 and 37, and by diffusion bonding the bases, the obtained base 3 has a single composition that does not contain other materials such as adhesives. In other words, the entire base 3 is made of only materials of the same composition.

[0073] The obtained base 3 can be superimposed on and joined to the electrostatic chuck member 2 via a joining member described below to form an electrostatic chuck device 1A. The above method may further include a step of providing an outlet and an inlet for the coolant. For example, if necessary, the method may further include a step of providing an outlet and an inlet for the coolant in the obtained base 3. Alternatively, the outlet and / or the inlet for the coolant may be provided in advance in at least one of the conductive ceramic plates to be used.

[0074] <Bonding Layer> The bonding layer 4 includes an insulating material contained in the dielectric substrate 11 constituting the electrostatic chuck member 2, and at least one of the highly thermally conductive material and the first 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.

[0075] The bonding layer 4 is formed using a bonding material (described later) containing the insulating material and at least one of the high thermal conductivity material and the first conductive material. When the bonding layer 4 is to be insulating, the bonding material should contain the high thermal conductivity material but not the first conductive material. When the bonding layer 4 is to be conductive, the bonding material should contain the first conductive material.

[0076] As the binder component, for example, a resin material can be used. As the resin material, one that is not likely to undergo cohesive failure due to thermal stress is preferred, and examples thereof include 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 not likely to undergo cohesive failure due to changes in thermal stress.

[0077] The ratio of the insulating material to at least one of the high thermal conductivity material and the first 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 high thermal conductivity material and the first conductive material" may be abbreviated as "high thermal conductivity material, etc."

[0078] In the manufactured electrostatic chuck device 1A, 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 1A, 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.

[0079] In the bonding layer 4, the volume ratio of the insulating material to the highly thermally conductive material or the like can be selected as needed, and may be, for example, 2:1 to 1:2, 0.7:1 to 1.9:1, 0.8:1 to 1.7:1, 1.2:1 to 1.5:1, or 1:1 to 2:1.

[0080] 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, 5% by mass to 48% by mass, 10% by mass to 45% by mass, or 20% by mass to 40% by mass.

[0081] The thickness of the bonding layer 4 is preferably 1 μm or more and 50 μm or less, more preferably 5 μm or more and 30 μm or less, and further preferably 10 μm or more and 20 μm or less.

[0082] The material (bonding material) of the bonding layer 4 is preferably a paste-like composition obtained by mixing an insulating material contained in the electrostatic chuck member 2, a highly thermally conductive material or the like contained in the base 3, and a binder component. The bonding layer 4 is formed between the electrostatic chuck member 2 and the base 3 by laminating the electrostatic chuck member 2 and the base 3 with a coating of the bonding material interposed therebetween, and then heating them while applying pressure (pressure heating) in a vacuum or in a non-oxidizing atmosphere.

[0083] The resulting bonding layer 4 contains the insulating material that is the material of the electrostatic chuck member 2. Therefore, by applying pressure and heat, the insulating material contained in the electrostatic chuck member 2 and the insulating material of the bonding layer 4 diffuse into each other. Furthermore, at the interface between the electrostatic chuck member 2 and the bonding layer 4, the insulating materials are sintered together. As a result, the bonding layer 4 and the electrostatic chuck member 2 are bonded together.

[0084] Similarly, the obtained bonding layer 4 contains the highly thermally conductive material, etc., which is the material of the base 3. Therefore, by applying pressure and heat, the highly thermally conductive material, etc., contained in the electrostatic chuck member 2 and the highly thermally conductive material, etc., of the bonding layer 4 are mutually diffused. Furthermore, at the interface between the electrostatic chuck member 2 and the base 3, the highly thermally conductive materials, etc., are sintered together. As a result, the base 3 and the electrostatic chuck member 2 are bonded together.

[0085] As a result, the electrostatic chuck member 2 and the base 3 are bonded together via the bonding layer 4 .

[0086] The coating film of the bonding material may be formed by applying the bonding material to at least one of the electrostatic chuck member 2 and the base 3 in a dry film thickness of 1 μm to 50 μm.

[0087] The conditions for the pressurization and heating may be arbitrarily selected as long as the electrostatic chuck member 2 and the base 3 can be bonded together, and it is preferable to perform the heat treatment under conditions of, for example, a pressure of 5 MPa or more at 1600°C to 1800°C for several hours. The temperature may be 1650°C to 1780°C or 1700°C to 1750°C, and the pressure may be 7 MPa or more or 10 MPa or more.

[0088] <Other Components> (Support Plate) The support plate 5 supports the base 3 from the lower surface 3b of the base 3. The support plate 5 is made of a material having a higher Young's modulus than the material of the base 3. For example, any of metal, MMC, and ceramics can be used as the material of the support plate 5. Among these, Al, which has a higher Young's modulus than the material of the base 3, is used as the support plate 5. ２ O ３ It is preferable to use a ceramic plate such as the above.

[0089] The ceramic material used for the support plate 5 is preferably the same as the material used for the electrostatic chuck member 2. Specific examples of the ceramic material include aluminum oxide, aluminum nitride, and Al. ２ O ３ By using the same material for the support plate 5 and the electrostatic chuck member 2, the difference in thermal expansion coefficient between the support plate 5 and the electrostatic chuck member 2 can be reduced, and warping of the electrostatic chuck device 1A can be suppressed.

[0090] (Insulator) The insulator 23 is inserted into the hole 17 and assembled to the base 3. That is, the insulator 23 functions as an insertion part that is inserted into the hole 17. The insulator 23 has a cylindrical shape that extends in the vertical direction. The power supply terminal 16 is disposed inside the insulator 23. The outer circumferential surface of the insulator 23 is joined to the inner surface of the hole 17 using a joining means such as adhesive. The insulator 23 insulates the metal base 3 from the power supply terminal 16.

[0091] The insulator 23 is made of, for example, ceramics. That is, the insulator 23 is made of an insulating material. This allows the insulator 23 to prevent the gas introduction hole from becoming a starting point for abnormal discharge. The insulator 23 has durability against plasma. Examples of ceramics that make up the insulator 23 include AlN, Al ２ O ３ , Si ３ N ４ , zirconium oxide (ZrO ２ ), sialon, boron nitride (BN), and SiC.

[0092] An upper end face of the insulator 23 (hereinafter referred to as upper end face 23a) is in contact with the electrostatic chuck member 2 or is disposed adjacent to the electrostatic chuck member with an insulating adhesive interposed therebetween.

[0093] (Power Supply Terminal) The power supply terminal 16 extends downward from the chucking electrode 13. The power supply terminal 16 is connected to an external power supply 21. The power supply 21 applies a voltage to the chucking electrode 13. The number, shape, etc. of the power supply terminals 16 are determined depending on the type of the chucking electrode 13, i.e., whether it is a monopolar type or a bipolar type.

[0094] The power supply terminal 16 passes through a first hole 17a in the dielectric substrate 11, a second hole 17b in the bonding layer 4, and a third hole 17c in the support plate 5. The first hole 17a is provided in a portion of the dielectric substrate 11 below the chucking electrode 13.

[0095] The first hole 17a, the second hole 17b, and the third hole 17c are each circular when viewed in the stacking direction. The first hole 17a, the second hole 17b, and the third hole 17c are in communication with the hole 17 of the base 3.

[0096] The inner circumferential surfaces of the first hole 17a, the second hole 17b, and the third hole 17c are continuous with the inner circumferential surface of the insulator 23 when viewed from the stacking direction. The inner diameters of the first hole 17a, the second hole 17b, and the third hole 17c are approximately equal to the inner diameter of the insulator 23 and slightly larger than the outer diameter of the power supply terminal 16.

[0097] According to the electrostatic chuck device 1A configured as described above, heat from the wafer W is easily transferred to the base 3 via the electrostatic chuck member 2 and the bonding layer 4, enabling stable temperature control of the wafer.

[0098] 5 is an explanatory diagram of an electrostatic chuck device 1B according to a second embodiment of the present invention. The electrostatic chuck device 1B of this embodiment has some components in common with the electrostatic chuck device 1A of the first embodiment. Therefore, the same components as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0099] The electrostatic chuck device 1B includes an electrostatic chuck member 2, a base 6, a support plate 5, an insulator (insertion component) 23, and a power supply terminal 16. The electrostatic chuck member 2 and the base 6 are stacked on top of each other with a bonding layer 4 interposed therebetween.

[0100] The base 6 is a conductive ceramic plate having a groove 6x on one surface 6a, and may have the same configuration as the conductive ceramic plate 30 having the groove 30x shown in Fig. 2. The base 6 is bonded to the electrostatic chuck member 2 via a bonding layer 4. A space surrounded by the groove 6x and the bonding layer 4 provided on the electrostatic chuck member 2 forms a flow path 6f through which a coolant flows.

[0101] Such an electrostatic chuck device 1B can be manufactured by a process of forming a continuous groove portion 6x in a band shape in a plan view on one surface of a conductive ceramic plate, and a process of overlapping the electrostatic chuck member 2 on one surface of the conductive ceramic plate (i.e., one surface 6a of the base 6) with the above-mentioned bonding material interposed therebetween and bonding the electrostatic chuck member 2 by diffusion bonding or the like.

[0102] The conductive ceramic plate that is the material of the base 6 contains a highly thermally conductive material and a first conductive material, and the dielectric substrate 11 that constitutes the electrostatic chuck member 2 is made of ceramics that contain an insulating material and a second conductive material. Since the bonding material contains the insulating material contained in the electrostatic chuck member 2 and at least one of the highly thermally conductive material and the first conductive material contained in the base 6, the electrostatic chuck member 2 and the base 6 can be bonded together in a suitable manner, as in the first embodiment.

[0103] Even with the electrostatic chuck device 1B configured as described above, the heat of the wafer W is easily transferred to the base 3 via the electrostatic chuck member 2 and the bonding layer 4, making it possible to stably control the temperature of the wafer.

[0104] 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.

[0105] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0106] The following test pieces were prepared: Test piece 1: Dielectric substrate (Al ２ O ３ Test piece 2: Conductive ceramic substrate (AlN:TiN=50:50, thickness 4 mm)

[0107] The conductive ceramic substrate was prepared by the following method.

[0108] (Preparation of Conductive Ceramic Substrate) A mixture of AlN particles having an average primary particle size of 1 μm, TiN particles having an average primary particle size of 1 μm, a dispersant, and ethanol was mixed for 12 hours using a ball mill using aluminum oxide media having a diameter of 1 mm to 5 mm. The AlN particles and TiN particles were weighed to have a volume ratio of 50:50.

[0109] The resulting mixture was then air-dried to obtain a raw material powder for the conductive ceramics, which was then heated at 500° C. in a nitrogen atmosphere for 12 hours.

[0110] The heated raw material powder was uniaxially press-molded at a pressure of 8 MPa using a die molding method to obtain a molded body, which was then set in a graphite mold and pressure-sintered at 1700°C for 2 hours under a nitrogen atmosphere at a pressure of 20 MPa to obtain a conductive ceramic substrate.

[0111] The obtained conductive ceramic substrate was processed to a thickness of 1 mm to obtain a test piece of the conductive ceramic substrate (test piece 2).

[0112] Fig. 6 is a scanning electron microscope (SEM) image of the conductive ceramic plate produced by the above method. More specifically, Fig. 6 is an image of the conductive ceramic substrate observed with a field emission scanning electron microscope (FE-SEM) (manufactured by Zeiss, product name: Merlin). In Fig. 6, the areas that appear relatively dark are areas occupied by AlN, and the areas that appear relatively light are areas occupied by TiN. It was confirmed from Fig. 6 that a conductive ceramic in which AlN and TiN were mixed approximately uniformly was obtained.

[0113] [Example 1] (Preparation of bonding material) AlN particles (average primary particle diameter 1 μm) and Al ２ O ３ The mixed powder obtained by mixing the SiO2 particles (average primary particle diameter: 0.12 μm) at a volume ratio of 50:50 was dispersed in a solvent for screen printing using a three-roll mill, thereby obtaining a bonding material of Example 1 in a paste form.

[0114] A coating film was formed by applying the bonding material by screen printing to one surface of the test piece 1. The coating film had a thickness of 12 μm.

[0115] Next, test piece 2 was placed on the formed coating film, and test piece 1 and test piece 2 were bonded together by heating and pressurizing them at 1680°C and 8 MPa in an argon atmosphere. As a result, test piece 1 and test piece 2 were bonded together, and it was confirmed that a dielectric substrate and a conductive ceramic substrate could be bonded together using the bonding material of Example 1.

[0116] [Example 2] TiN particles (average primary particle diameter 1 μm) were used instead of AlN particles. ２ O ３ A bonding material of Example 2 was obtained in the same manner as in Example 1, except that the volume ratio of the powder to the particles was 60:40.

[0117] Test piece 1 and test piece 2 were bonded in the same manner as in Example 1, except that the bonding material of Example 2 was used. As a result, test piece 1 and test piece 2 were bonded, and it was confirmed that a dielectric substrate and a conductive ceramic substrate could be bonded using the bonding material of Example 2.

[0118] [Comparative Example 1] AlN particles were not used. ２ O ３A bonding material of Comparative Example 1 was obtained in the same manner as in Example 1, except that only particles were used.

[0119] An attempt was made to bond test piece 1 and test piece 2 in the same manner as in Example 1, except that the bonding material of Comparative Example 1 was used, but test piece 1 and test piece 2 were not bonded.

[0120] Comparative Example 2 Test piece 1 and test piece 2 were bonded (adhered) in the same manner as in Example 1, except that a silicone adhesive, which is commonly used in this technical field for bonding a dielectric substrate and an alumina base, was used instead of the bonding material.

[0121] [Heat Transfer Test (Simulation)] For electrostatic chuck devices formed under the following conditions, the heat of a wafer placed on the electrostatic chuck device was simulated to confirm the effect of transferring the heat of the wafer to the base side. Dielectric substrate material: Al ２ O ３ -SiC composite sintered body (Al ２ O ３ :SiC (mass ratio) = 95:5) Material of base 1: conductive ceramics (AlN:TiN (mass ratio) = 50:50) Material of base 2: aluminum (Simulation targets) Electrostatic chuck device A: Dielectric substrate and base 1 are bonded with a bonding layer having the same composition as the mixed powder of bonding materials in Example 1. Electrostatic chuck device B: Dielectric substrate and base 1 are bonded with a bonding layer having the same composition as the mixed powder of bonding materials in Example 2. Electrostatic chuck device C: Dielectric substrate and base 1 are bonded with a bonding layer having the same composition as the inorganic material of the bonding material in Comparative Example 1. Electrostatic chuck device D: Dielectric substrate and base 2 are bonded with the silicone adhesive of Comparative Example 2.

[0122] When the same predetermined amount of heat was input to all electrostatic chuck devices, the wafer temperature of electrostatic chuck device A was found to be lower than the wafer temperature of electrostatic chuck device D, when the wafer temperature of electrostatic chuck device D was used as the reference.

[0123] Similarly, the wafer temperature of electrostatic chuck device B was lower than the wafer temperature of electrostatic chuck device D.

[0124] On the other hand, the wafer temperature of the electrostatic chuck device C was higher than the wafer temperature of the electrostatic chuck device D.

[0125] From the above results, it was confirmed that in the electrostatic chuck device of this embodiment, which is formed with a base made of conductive ceramics, heat from the wafer W is easily transferred to the base via the electrostatic chuck member and the bonding layer, and stable temperature control of the wafer is possible.

[0126] Although the results of Examples 1 and 2 and Comparative Examples 1 and 2 were obtained using test specimens, it is believed that similar behavior also occurs at the interface between the electrostatic chuck member 2 made of a dielectric substrate and the base 3 made of a conductive ceramic. That is, in an electrostatic chuck device in which the above-described electrostatic chuck member and the above-described conductive ceramic base are bonded together with a bonding layer containing a highly thermally conductive material or the like and an insulating material, the dielectric substrate and the conductive substrate are suitably bonded together via the bonding layer. Furthermore, in such an electrostatic chuck device, it is expected that heat from a wafer supported by the electrostatic chuck member is easily transferred to the base 3 via the electrostatic chuck member 2 and the bonding layer 4, enabling stable temperature control of the wafer.

[0127] From the above results, it was confirmed that the present invention is useful.

[0128] 1A, 1B Electrostatic chuck device 2 Electrostatic chuck member 2a Mounting surface 2b Back surface 3, 6 Base 3a Support surface 3b Lower surface 3f, 6f Flow path 4 Bonding layer 5 Support plate 6a, 30a One surface 6x, 30x, 31x Groove portion 11 Dielectric substrate 13 Adsorption electrode 16 Power supply terminal 17 Hole portion 17a First hole 17b Second hole 17c Third hole 21 Power source 22 High frequency power source 23 Insulator 23a Upper end surface 30, 31, 36, 37 Conductive ceramic plate 30a One surface 31a, 36a, 37a Opposing surface 35 Substrate 35x Through hole 37 Conductive ceramic plate W Wafer

Claims

1. An electrostatic chuck device comprising: an electrostatic chuck member having a dielectric substrate and an internal electrode; a base; and a bonding layer bonding the electrostatic chuck member to the base, wherein the base includes a highly thermally conductive material and a first conductive material; the dielectric substrate is made of ceramics including an insulating material and a second conductive material; and the bonding layer includes the insulating material and at least one of the highly thermally conductive material and the first conductive material.

2. The high thermal conductivity material is AlN, SiC, GaN, 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 the first conductive material and the second conductive material are at least one selected from the group consisting of C, carbon, aluminum, copper, silver, and gold, and the first conductive material and the second conductive material are at least one selected from the group consisting of SiC, TiO ２ , TiN, TiC, W, WC, Mo, MoC, Mo ２ 2. The electrostatic chuck device according to claim 1, wherein the material is at least one selected from the group consisting of C, TaC, TaN, NbC, VC, and C.

3. An electrostatic chuck device according to claim 2, wherein said high thermal conductivity material is AlN and said first conductive material is TiN.

4. An electrostatic chuck device according to any one of claims 1 to 3, wherein the base is of a single composition.

5. A method for manufacturing a base, comprising: forming a continuous groove portion in a band shape in a planar view on one surface of at least one of a pair of conductive ceramic plates; and overlapping and bonding the pair of conductive ceramic plates with the groove portion facing the other conductive ceramic plate, wherein the conductive ceramic plate includes a highly thermally conductive material and a first conductive material, and the space surrounded by the groove portion and the other conductive ceramic plate is a flow path through which a refrigerant flows.

6. A method for manufacturing a base, comprising the steps of: forming a continuous band-shaped through hole in one surface of a substrate when viewed from above; and sandwiching and bonding the substrate between a pair of conductive ceramic plates, wherein the substrate and the pair of conductive ceramic plates each contain a highly thermally conductive material and a first conductive material; and the space surrounded by the through hole and the pair of conductive ceramic plates is a flow path through which a refrigerant flows.

7. A method for manufacturing an electrostatic chuck device, comprising the step of overlapping and bonding a base manufactured by the base manufacturing method described in claim 5 or 6 with an electrostatic chuck member having a dielectric substrate and an internal electrode via a bonding material, wherein the dielectric substrate is made of ceramics containing an insulating material and a second conductive material, and the bonding material contains the insulating material and at least one of the highly thermally conductive material and the first conductive material.

8. A method for manufacturing an electrostatic chuck device, comprising: a step of forming a continuous groove portion in a band shape in a plan view on one surface of a conductive ceramic plate; and a step of superimposing and bonding an electrostatic chuck member having a dielectric substrate and an internal electrode on one surface of the conductive ceramic plate via a bonding material, wherein the conductive ceramic plate includes a highly thermally conductive material and a first conductive material, the dielectric substrate is made of ceramics including an insulating material and a second conductive material, a space surrounded by the groove portion and the electrostatic chuck member is a flow path through which a coolant flows, and the bonding material includes the insulating material and at least one of the highly thermally conductive material and the first conductive material.

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