Holding device

Abstract

To provide other technique for suppressing corrosion by plasma of a joint part joining a plate-like part and a base part, in a holding device.SOLUTION: A holding device includes a plate-like part formed into a plate shape, a base part which supports the plate-like part and is formed into a plate shape, a joint part which is arranged between the plate-like part and the base part and is composed of a resin adhesive bonding the plate-like part and the base part, and a protective member coating at least a part of the outer peripheral surface of the joint part, wherein the protective member contains a matrix resin which has a skeleton of perfluoropolyether and contains a matrix resin containing a resin component the same as the resin adhesive.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a holding device.

Background Art

[0002] Conventionally, as a holding device for holding an object, for example, an electrostatic chuck for holding an object such as a wafer when manufacturing a semiconductor is known. An electrostatic chuck generally includes a plate-like portion on which an object is placed, a base portion that supports the plate-like portion and is formed in a plate shape, and a joining portion that is disposed between the plate-like portion and the base portion and joins the plate-like portion and the base portion. As the material of the joining portion, an adhesive made of a silicone resin, a composite resin obtained by adding a thermally conductive filler such as aluminum oxide or aluminum nitride to the silicone resin, or the like may be used.

[0003] In such a holding device, when repeatedly exposed to various reaction gases used in film formation or etching by plasma in a semiconductor manufacturing process, the side surface of the joining portion may be eroded by the plasma, generating particles. To address such problems, for example, Patent Document 1 proposes a technique of forming a recess in the peripheral portion of the adhesive layer and disposing an annular polytetrafluoroethylene (PTFE) protective member so as to press the wall surface of the recess. Patent Document 2 proposes a technique of suppressing corrosion of the joining layer by plasma by providing a ring-shaped first joining layer made of an alumina sintered body on the inner peripheral surface of a through hole used as a part of a lift pin hole or a gas supply hole in the joining portion.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the technologies described in Patent Documents 1 and 2, a gap is generated between the annular protective member and the joint portion, and even with the annular protective member, the joint portion may be corroded. Note that these problems are not limited to electrostatic chucks, and are common problems in various holding devices such as semiconductor manufacturing devices such as plasma etching devices.

[0006] The present disclosure has been made to solve at least a part of the above-described problems, and an object thereof is to provide another technique for suppressing plasma corrosion of a joint portion that joins a plate-shaped portion and a base portion in a holding device.

Means for Solving the Problems

[0007] The present disclosure can be realized in the following forms. (1) According to one aspect of the present disclosure, a holding device for holding an object is provided. This holding device includes a plate-shaped portion formed in a plate shape, a base portion that supports the plate-shaped portion and is formed in a plate shape, a joint portion disposed between the plate-shaped portion and the base portion and made of a resin adhesive that joins the plate-shaped portion and the base portion, and a protective member that covers at least a part of the outer peripheral surface of the joint portion. The protective member has a perfluoropolyether skeleton and contains a matrix resin containing a resin component of the same type as the resin adhesive.

[0008] According to the holding device of this aspect, since the protective member contains a matrix resin having a perfluoropolyether (hereinafter also referred to as PFPE) skeleton that is hardly corroded by plasma, the protective member is hardly corroded by plasma. Therefore, according to the holding device of this aspect, erosion of the joint portion by plasma is suppressed, and generation of particles can be suppressed even when the holding device is exposed to plasma.

[0009] Furthermore, in the holding device of this form, since the matrix resin contained in the protective member contains a resin component of the same type as the resin adhesive forming the joint portion, the linear thermal expansion coefficients of the joint portion and the protective member can be made closer to each other, and peeling, cracking, etc. accompanying thermal expansion and thermal contraction of the joint portion and the protective member can be suppressed.

[0010] (2) In the holding device of the above form, the ratio of the linear thermal expansion coefficient of the protective member to the linear thermal expansion coefficient of the resin adhesive may be 0.1 or more and 2 or less. By doing so, peeling, cracking, etc. accompanying thermal expansion and thermal contraction of the protective member can be more suppressed.

[0011] (3) In the holding device of the above form, the protective member may be chemically bonded to the plate-shaped portion and the base portion, respectively. By doing so, peeling between the protective member and the plate-shaped portion and peeling between the protective member and the base portion can be suppressed, so generation of a gap between the protective member and the plate-shaped portion and a gap between the protective member and the base portion can be suppressed, and intrusion of plasma through those gaps can be suppressed, so erosion of the joint portion by plasma can be more suppressed.

[0012] (4) In the holding device of the above form, the protective member may be further chemically bonded to the joint portion. By doing so, peeling between the joint portion and the protective member can be suppressed, and furthermore, erosion of the joint portion by plasma can be suppressed.

[0013] (5) In the holding device of the above form, it may have a seal member provided on the outer periphery of the protective member, and the protective member and the seal member may be in close contact. By doing so, the protective member is protected from plasma, which further leads to protection of the joint portion. Further, there may be a gap between the protective member and the sealing member. By doing so, it is possible to absorb the volume change due to the difference in the coefficient of thermal expansion between the protective member and the sealing member. Further, even if a gap exists between the protective member and the sealing member and plasma enters the gap, since the plasma resistance of the protective member is high, corrosion of the joint portion due to plasma can be suppressed.

[0014] (6) The holding device according to the above aspect, further comprising a through hole penetrating the joint portion, and a matrix resin having a perfluoropolyether skeleton and containing a resin component of the same type as the resin adhesive, the matrix resin being formed on at least a part of the inner periphery of the through hole. And a through-hole protection member. By doing so, corrosion of the joint portion due to plasma entering the through hole can be suppressed.

[0015] The present disclosure can be realized in various forms other than the above, for example, in the form of a semiconductor manufacturing apparatus including a holding device, a manufacturing method of a holding device, and the like.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0017] A. First Embodiment: FIG. 1 is an explanatory diagram schematically showing the configuration of an electrostatic chuck 10 according to the first embodiment. FIG. 2 is an explanatory diagram schematically showing a cross-sectional configuration of the electrostatic chuck 10. In the figures, for the purpose of specifying directions, XYZ axes orthogonal to each other are shown. In this specification, for convenience, the positive Z-axis direction is referred to as the upward direction, and the negative Z-axis direction is referred to as the downward direction. However, the electrostatic chuck 10 may actually be installed in a direction different from such a direction. Note that each of the above figures schematically represents the arrangement of each part and does not accurately represent the ratio of the dimensions of each part.

[0018] The electrostatic chuck 10 is a device that adsorbs and holds an object by electrostatic attraction, and is used, for example, to fix a wafer W as an object in a vacuum chamber of a semiconductor manufacturing apparatus. The electrostatic chuck 10 includes a plate-like portion 20, a base portion 30, a joining portion 40, a protection member 50, and a seal member 60. The plate-like portion 20, the joining portion 40, and the base portion 30 are laminated in this order toward the -Z-axis direction (vertically downward). The electrostatic chuck 10 in the present embodiment is also referred to as a "holding device".

[0019] The plate-like portion 20 is a substantially circular planar plate-like member having a first surface S1 on the side where the object is placed and a second surface S2 that is the back surface of the first surface S1, and is formed mainly of ceramic (for example, aluminum oxide, aluminum nitride, etc.). In this specification, that a specific component is "the main component" or "the material mainly forming" means that the content rate of the specific component is 50% by volume or more. The diameter of the plate-like portion 20 may be, for example, about 50 mm to 500 mm, and is usually about 200 mm to 350 mm. The thickness of the plate-like portion 20 may be, for example, about 1 mm to 10 mm. In other embodiments, the plate-like portion may be mainly composed of a material other than ceramic, such as a resin such as polyimide.

[0020] As shown in FIG. 2, an adsorption electrode 22 is disposed inside the plate-shaped portion 20. The adsorption electrode 22 is formed of a conductive material such as tungsten or molybdenum, for example. When a voltage is applied to the adsorption electrode 22 from a power source (not shown), an electrostatic attraction is generated, and the electrostatic attraction adsorbs and fixes the wafer W to the first surface S1 of the plate-shaped portion 20. The adsorption electrode 22 may be bipolar or unipolar.

[0021] Also, inside the plate-shaped portion 20, a spiral heater 24 is disposed below the adsorption electrode 22 (on the minus Z-axis side) when viewed in the Z-axis direction. In the present embodiment, the heater 24 is a metallized layer formed of tungsten, molybdenum, or the like. The shape of the heater 24 is not limited to the present embodiment, and may be, for example, a disk shape or the like. In other embodiments, the plate-shaped portion 20 may not include the heater 24.

[0022] The base portion 30 is a substantially circular planar plate-shaped member that is disposed on the second surface S2 side of the plate-shaped portion 20 and supports the plate-shaped portion 20. The base portion 30 can include, for example, at least one kind of metal among aluminum, magnesium, molybdenum, titanium, tungsten, and nickel. Aluminum has a relatively high thermal conductivity, is easy to process, and has a low cost. Therefore, when the base portion 30 is configured using aluminum, the cooling efficiency of the plate-shaped portion 20 and the wafer W by the base portion 30 can be increased, and the manufacturing cost of the electrostatic chuck 10 can be suppressed, which is desirable. From the viewpoint of increasing the cooling efficiency by the base portion 30 while suppressing the manufacturing cost, it is desirable that the metal content ratio in the base portion 30 is high, and the base portion 30 desirably contains a metal as a main component. For example, it is desirable to contain 90% by mass or more of aluminum with high versatility (for example, be composed of an aluminum alloy such as A6061 or A5052). However, the base portion 30 may contain a component other than a metal such as ceramic. The diameter of the base portion 30 may be, for example, about 220 mm to 550 mm, and is usually 220 mm to 350 mm. The thickness of the base portion 30 may be, for example, about 20 mm to 40 mm.

[0023] Inside the base portion 30, a plurality of refrigerant flow paths 32 are formed along the XY plane. (Fig. 2) By flowing a refrigerant such as a fluorine-based inert liquid, water, or liquid nitrogen through the refrigerant flow path 32, the base portion 30 is cooled. Then, the heat transfer between the base portion 30 and the plate-like portion 20 via the joint portion 40 cools the plate-like portion 20, and the wafer W held on the first surface S1 of the plate-like portion 20 is cooled. Thereby, temperature control of the wafer W is realized. In addition to the form having the refrigerant flow path 32 inside the base portion 30, the base portion 30 may be provided with a cooling function by cooling the base portion 30 from the outside of the base portion 30.

[0024] The joint portion 40 is a substantially circular planar plate-like member having a smaller diameter than the plate-like portion 20, and is disposed between the plate-like portion 20 and the base portion 30 to join the plate-like portion 20 and the base portion 30. The joint portion 40 is formed of a resin adhesive (also called a silicone resin adhesive) using a silicone resin as a matrix resin and containing an inorganic filler (also called a filler). In other embodiments, an acrylic resin, an epoxy resin, or the like can be used instead of the silicone resin. The silicone resin is desirable because it has a relatively low elastic modulus, so it has a high function of relaxing the thermal stress generated at the joint portion 40, and also has a relatively high heat-resistant temperature. The filler is an additive that does not participate in the reaction, and can be observed using, for example, a scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), a digital microscope, or the like.

[0025] As the inorganic filler, various inorganic materials including ceramics, metal oxides, metals, or other inorganic compounds can be used. For example, at least one of aluminum nitride (AlN), aluminum oxide (alumina: Al2O3), zirconium oxide (zirconia: ZrO2), yttrium oxide (yttria: Y2O3), yttrium fluoride (YF3), silicon carbide (SiC), silicon nitride (Si3N4), silicon dioxide (silica: SiO2), iron oxide, barium sulfate, calcium carbonate, boron nitride, carbon black, graphite, carbon nanotubes, and magnesium oxide can be used. Since such inorganic materials generally have a higher thermal conductivity than the resin contained in the adhesive, including the inorganic filler in the adhesive can increase the thermal conductivity at the joint 40 and improve the heat uniformity of the plate-like portion 20. In particular, from the viewpoint of having a relatively high thermal conductivity and being easy to suppress the thermal resistance of the joint 40, aluminum nitride, aluminum oxide, and silicon carbide are preferable as the inorganic material, and aluminum nitride and aluminum oxide are particularly preferable. The shape of the inorganic filler is not particularly limited, but a spherical (powder) shape is preferable.

[0026] The joint portion 40 may further contain a silane coupling agent for promoting curing or adhesion to impart adhesiveness, a crosslinking agent, a reaction inhibitor for adjusting the curing rate of the resin adhesive, or a viscosity modifier, etc. There is no particular limitation on the silane coupling agent, and for example, it can be appropriately selected from conventionally known silane coupling agents such as those having any one of a vinyl group, an epoxy group, a methacryl group, an amino group, a mercapto group, and an isocyanate group as an organic reactive group. Further, instead of the above silane coupling agent, a titanate coupling agent or an aluminate coupling agent may be used. As the crosslinking agent, an organohydrogenpolysiloxane having at least three hydrosilyl groups in one molecule can be used. More specifically, for example, at least one of polymethylhydrogensiloxane and poly(dimethylsiloxane-methylhydrogensiloxane) can be used. As the reaction inhibitor, various conventionally known reaction inhibitors can be used, and for example, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, 1,1,3,3-tetramethyl-1,3-divinyldisiloxane, triallyl isocyanurate, etc. can be used. As the viscosity modifier, various conventionally known viscosity modifiers can be used, and for example, fumed silica, pyrogenic silica, colloidal silica, fumed alumina, pyrogenic alumina, colloidal alumina, etc. can be used. The types and addition amounts of the above-described catalyst, silane coupling agent, crosslinking agent, reaction inhibitor, or viscosity modifier, etc. may be appropriately selected according to, for example, the type of the resin constituting the joint portion 40.

[0027] For joining the plate-like portion 20 and the base portion 30, a sheet-like or varnish-like silicone resin adhesive can be used. When using it in a sheet form, after cutting the silicone adhesive into a predetermined shape, the plate-like portion 20 and the base portion 30 are joined in a vacuum via the sheet-like silicone adhesive and cured at a temperature of 100 °C or higher, whereby the plate-like portion 20 and the base portion 30 can be joined. When using a varnish-like silicone adhesive, it is applied to the base portion 30 by the screen printing method, joined with the plate-like portion 20 in a vacuum, and cured at a temperature of 100 °C or higher, whereby the plate-like portion 20 and the base portion 30 can be joined. Here, a resin wall for preventing outflow may be formed on the base portion 30. As the resin wall, the protective member 50 may be used.

[0028] The seal member 60 is formed in an annular shape and is provided outside the outer peripheral surface 42 of the joint portion 40. The seal member 60 is provided to prevent the joint portion 40 from being exposed to plasma or process gas, and as shown in FIG. 2, it is in contact with the plate-like portion 20 and the base portion 30.

[0029] The seal member 60 can be formed of a fluororesin such as FFKM (perfluoroelastomer: fluororubber), PTFE (Polytetrafluoroethylene), etc.

[0030] The protective member 50 is an annular resin member that covers the entire outer peripheral surface 42 of the joint portion 40. Specifically, the protective member 50 is formed in an annular shape with an inner diameter substantially matching the outer diameter of the joint portion 40 and a height substantially matching the height of the joint portion 40. In the present embodiment, the protective member 50 covers the entire outer peripheral surface 42 of the joint portion 40, but in other embodiments, the protective member may cover at least a part of the outer peripheral surface 42 of the joint portion 40.

[0031] The protective member 50 contains a matrix resin having a perfluoropolyether (PFPE) backbone and containing a resin component of the same type as the resin adhesive forming the joint portion 40. In the present embodiment, as described above, since the joint portion 40 is formed of a silicone resin adhesive, the matrix resin forming the protective member 50 contains a silicone resin. In other embodiments, for example, when the joint portion 40 is formed of an epoxy resin adhesive, the protective member 50 contains an epoxy resin. Also, when the joint portion 40 is formed of an acrylic resin adhesive, the protective member 50 contains an acrylic resin. Here, the resin component contained in the matrix resin of the protective member 50 only needs to be a resin component of the "same type" as the resin adhesive forming the joint portion, and does not have to be the "same" resin component. For example, the organic substituents of the silicone resin contained in the protective member 50 and the silicone resin contained in the joint portion 40 may be different.

[0032] The matrix resin of the protective member 50 is not particularly limited as long as it has a PFPE backbone and contains a resin component of the same type as the resin adhesive forming the joint portion 40, but those having a phenyl group are preferable. The phenyl group (-C6H5) is larger than the methyl group (-CH3) and has a larger free volume, so it has the effect of lowering the glass transition temperature. In addition to the phenyl group, an ethyl group, a propyl group, a trifluoropropyl group, etc. may also be used. Thereby, the elastic modulus at low temperatures can be lowered. When the elastic modulus is reduced, the protective member 50 can be made softer, and peeling and cracking can be suppressed even when the volume expands and contracts.

[0033] Since the protective member 50 contains, as a base material, a resin having a PFPE as a component that is hardly corroded by plasma, it is hardly corroded by plasma. Therefore, the joint portion 40 is protected by the protective member 50, and erosion of the joint portion 40 by plasma can be suppressed.

[0034] In addition, since the matrix resin contained in the protection member 50 includes a resin component of the same type as the resin adhesive forming the joint portion 40, the linear thermal expansion coefficients of the joint portion 40 and the protection member 50 can be made closer to each other, and peeling, cracking, etc. of the protection member 50 due to thermal expansion and thermal contraction of the joint portion 40 and the protection member 50 can be suppressed. Therefore, plasma exposure of the joint portion 40 due to deterioration of the protection member 50 can be suppressed. Further, deterioration of the protection member 50 due to repeated temperature changes during use of the electrostatic chuck 10 can be suppressed.

[0035] FIG. 3 is an explanatory view showing an enlarged view of the X portion in FIG. 2. FIG. 3(A) shows the normal temperature to high temperature (for example, 200 ° C.), and FIG. 3(B) shows the low temperature (for example, -60 ° C. to -70 ° C.). When the temperature in the vacuum chamber in which the electrostatic chuck 10 is disposed is normal temperature to high temperature, as shown in FIG. 3(A), since the plasma and the process gas are sealed by the seal member 60, the plasma and the process gas do not enter inside the seal member 60. On the other hand, when the temperature in the vacuum chamber in which the electrostatic chuck 10 is disposed is low, as shown in FIG. 3(B), since the seal member 60 contracts, a gap is generated between the plate-like portion 20 and the seal member 60 and between the base portion 30 and the seal member 60, and there is a risk that the plasma and the process gas may enter inside the seal member 60 through the gap.

[0036] As shown in FIG. 3(B), even if the plasma and the process gas enter inside the seal member 60, since the outer peripheral surface 42 of the joint portion 40 is covered with the protection member 50 having high plasma resistance as described above, the joint portion 40 can be protected from exposure to the plasma and the process gas. As a result, corrosion of the joint portion 40 due to the plasma and the process gas can be suppressed, and particles can be suppressed.

[0037] The elastic modulus (dynamic storage elastic modulus) of the protective member 50 is not particularly limited, but the elastic modulus at -50°C is preferably 0.1 MPa to 1 GPa, the elastic modulus at 25°C is preferably 0.1 to 5 MPa, and the elastic modulus at 200°C is preferably 0.1 to 5 MPa. By doing so, even if the protective member 50 expands and contracts with temperature changes, since the elongation is good, it is difficult to form a gap with the joint portion 40. As a result, even with temperature changes, the joint portion 40 can be protected from plasma.

[0038] The ratio of the linear thermal expansion coefficient of the protective member 50 to the linear thermal expansion coefficient of the joint portion 40 is not particularly limited, but is preferably 0.1 to 2, and more preferably 0.2 to 1.4. By doing so, the linear thermal expansion coefficient of the protective member 50 can be made close to the linear thermal expansion coefficient of the joint portion 40, so that the difference in volume change due to temperature change can be reduced, and peeling of the protective member 50 from the joint portion 40 and cracking of the protective member 50 can be suppressed.

[0039] In the electrostatic chuck 10 of the present embodiment, there is a gap between the protective member 50 and the seal member 60 (FIG. 2). Therefore, it is possible to absorb the volume change due to the difference in thermal expansion coefficient between the protective member 50 and the seal member 60. In other embodiments, the protective member 50 and the seal member 60 may be in close contact. When the protective member 50 and the seal member 60 are in close contact, the protective member 50 is protected from plasma, and further, it leads to the protection of the joint portion 40.

[0040] Further, since PFPE is in a liquid state before curing, the state of the protective member before curing is liquid. Hereinafter, the material of the protective member 50 before curing is also referred to as "pre-cured protective member material". For example, when manufacturing the electrostatic chuck 10, after applying the pre-cured protective member material to the outer peripheral surface 42 of the joint portion 40 and then curing it, the protective member 50 is in close contact with the joint portion 40. Therefore, the gap between the joint portion 40 and the protective member 50 is reduced, and erosion of the joint portion 40 by plasma can be further suppressed. Note that the protective member 50 does not have to be adhered to the joint portion 40.

[0041] The protective member 50 may contain a silane coupling agent for promoting curing and adhesion to impart adhesiveness, an inorganic filler, a crosslinking agent, a reaction inhibitor for adjusting the curing rate of the adhesive, a viscosity modifier, or the like. As these additives, those similar to those that can be used for the joint portion 40 described above can be used. By including an inorganic filler, the protective member 50 can improve the thermal conductivity. Since the matrix resin of the protective member 50 has a PFPE skeleton, it has excellent plasma resistance and is less likely to be corroded by plasma, so that the generation of particles can be suppressed.

[0042] The protective member 50 may not be chemically bonded to the plate-like portion 20 and the base portion 30, respectively, but it is preferably chemically bonded. Thereby, the exposure of the joint portion 40 to plasma and process gas can be further suppressed. For example, when the plate-like portion 20 contains ceramic as a main component and the base portion 30 contains metal as a main component, since there is an oxide or an oxide film on the surface of each part, it can be bonded to the adhesion-imparting component contained in the fluorine adhesive through oxygen such as a hydroxy group on the surface.

[0043] Further, the protective member 50 may not be chemically bonded to the joint portion 40, but it is preferably chemically bonded. Thereby, the exposure of the joint portion 40 to plasma and process gas can be further suppressed. When the joint portion 40 is formed of a silicone adhesive, since the surface is hydrophobic and difficult to adhere, by modifying the surface to be hydrophilic by plasma treatment or the like, it can be bonded to the adhesion-imparting component contained in the fluorine adhesive (adhesive having a PFPE skeleton). In addition to plasma treatment, corona treatment, ultraviolet irradiation, or the like may be performed.

[0044] Furthermore, it is desirable that the protective member 50 has a high thermal decomposition temperature. Since it can be used at a wide range of temperatures from low to high, for example, a composite material of PFPF and silicone in which the weight loss at 200 °C is less than 0.1% and the weight loss at 300 °C is less than 1% is preferable. The thermal decomposition temperature can be confirmed using thermogravimetric differential thermal analysis (TG-DTA).

[0045] As described above, in the electrostatic chuck 10 of the present embodiment, the joint portion 40 is formed of a resin adhesive mainly composed of a silicone resin. Since the silicone resin has high flexibility, for example, even when the plate-like portion 20 and the base portion 30 are formed of materials having different coefficients of thermal expansion, the stress generated by the temperature difference can be relaxed, contributing to the improvement of the flatness of the plate-like portion 20. Further, since the joint portion 40 contains an inorganic filler and has high thermal conductivity, the heat uniformity of the first surface S1 of the plate-like portion 20 can be improved. On the other hand, since the silicone resin does not have high plasma resistance, if the joint portion 40 is exposed to plasma, there is a risk that the joint portion 40 will be corroded by the plasma and the inorganic filler contained in the joint portion 40 will come out, that is, a so-called particle problem will occur.

[0046] On the contrary, according to the electrostatic chuck 10 of the present embodiment, since it has the protective member 50 that covers the entire outer peripheral surface 42 of the joint portion 40, the joint portion 40 is not exposed to plasma. In the present embodiment, since the protective member 50 contains a matrix resin having a PFPE skeleton that is hardly corroded by plasma, even if the exposure of the protective member 50 to plasma is repeated, it is hardly corroded by plasma. Therefore, even when the electrostatic chuck 10 is exposed to plasma, the corrosion of the protective member 50 is suppressed, and the erosion of the joint portion 40 by plasma can be suppressed. As a result, the generation of particles can be suppressed.

[0047] Further, since the matrix resin contained in the protective member 50 contains a resin component of the same type as the resin adhesive forming the joint portion 40, the linear coefficient of thermal expansion of the joint portion 40 and the protective member 50 can be made closer, and the peeling, cracking, etc. of the protective member 50 accompanying the thermal expansion and thermal contraction of the joint portion 40 and the protective member 50 can be suppressed. Therefore, the plasma exposure of the joint portion 40 due to the deterioration of the protective member 50 can be suppressed. In addition, the deterioration of the protective member 50 accompanying the repeated temperature change due to the use of the electrostatic chuck 10 can be suppressed. The plasma exposure of the joint portion 40 can be suppressed for a relatively long period.

[0048] In addition, since PFPE changes from a liquid to a solid (cures) due to heat or light, when manufacturing the electrostatic chuck 10, after joining the plate-shaped portion 20 and the base portion 30 by the joining portion 40, a liquid material (pre-curing protective member material) before curing of the constituent material of the protective member 50 is applied to the outer peripheral surface 42 of the joining portion 40 and cured by heat or light, whereby the protective member 50 can be easily formed.

[0049] In addition, when the protective member 50 is formed by the above method, the protective member 50 is formed in close contact with the outer peripheral surface 42 of the joining portion 40 with substantially no gap, and plasma exposure of the joining portion 40 can be further suppressed. Therefore, deterioration of the joining portion 40 and generation of particles accompanying the deterioration can be further suppressed.

[0050] In addition, since the pre-curing protective member material of the protective member 50 is liquid, unlike the case where the outer peripheral surface 42 of the joining portion 40 is protected by an O-ring or a sintered body, in the manufacturing process of the electrostatic chuck 10, the shape can be made in accordance with the shapes of the plate-shaped portion 20, the base portion 30, and the joining portion 40, and component design can be made unnecessary.

Example

[0051] Hereinafter, the holding device of the present disclosure will be described based on examples. Here, as samples corresponding to various protective members mainly different in matrix resin, film-like samples from Sample 1 to Sample 4 were produced, and the elastic modulus, linear thermal expansion coefficient, and adhesiveness were evaluated. Further, as reference examples, Samples 5 and 6 of a silicone resin adhesive as an adhesive for forming the joining portion 40 were produced and evaluated in the same manner. Here, the dynamic storage elastic modulus is evaluated as the elastic modulus.

[0052] The matrix resins of Samples 1 to 3 have a PFPE backbone and contain silicone. That is, Samples 1 to 3 contain silicone as a resin component of the same type as the resin adhesive forming the joint 40. In the examples, Sample 1 was prepared using SIFEL2662 (SIFEL is a registered trademark) of Shin-Etsu Chemical Co., Ltd. SIFEL2662 is a high thixotropic type (high thixotropy) and contains fine powder. Sample 2 was prepared using SIFELX-71-359 of Shin-Etsu Chemical Co., Ltd. SIFELX-71-359 does not contain a filler. Sample 3 was prepared using SIFELX-71-6207 of Shin-Etsu Chemical Co., Ltd. SIFELX-71-6207 is a low-temperature curing type and is easy to react.

[0053] Figure 4 is an explanatory diagram showing the reaction of silicone. Figure 4(A) shows an example of curing by an addition reaction using a Pt-based compound (platinum compound) as a catalyst. A vinyl group (-CH=CH2) and SiH form a bond in the presence of a platinum catalyst. Figure 4(B) shows the curing reaction of Samples 1 to 3. Samples 1 to 3 have a vinyl group at the end of PFPE and are cured by reacting with a silicone containing SiH.

[0054] The matrix resin of Sample 4 is an epoxy resin, and 2087 of Three Bond Co., Ltd. was used. Sample 5 uses a silicone adhesive that does not contain a phenyl group, and Sample 6 is a silicone adhesive that contains a phenyl group (-C6H5).

[0055] Figure 5 is a diagram showing the structural formula of silicone. Figure 5(A) shows a general silicone, and Figure 5(B) shows a silicone containing a phenyl group. Since the phenyl group (-C6H5) is larger than the methyl group (-CH3) and the free volume is increased, it has the effect of lowering the glass transition temperature. Thereby, the elastic modulus at low temperature can be lowered (Example Sample 6).

[0056] <Preparation of Each Sample> · Samples 1 and 2: The paste-like resins (SIFEL2662, SIFELX71-359) were formed into films, heated at 150 °C for 1 hour to cure, and made into film-like cured bodies with a thickness of 100 μm.

[0057] · Sample 3: The two-component paste-like resin (SIFELX71-6207) was mixed at a ratio of 1:1, then formed into a film, heated at 80 °C for 1 hour to cure, and made into a film-like cured body with a thickness of 100 μm.

[0058] · Sample 4: The two-component paste-like resin (2087) was mixed at a ratio of 1:1, then formed into a film, heated at 80 °C for 1 hour to cure, and made into a film-like cured body with a thickness of 100 μm.

[0059] · Samples 5 and 6: The paste-like resin was formed into a film, heated at 100 °C for 10 hours and then at 150 °C for 10 hours to cure, and made into a film-like cured body with a thickness of 100 μm. The method for preparing the paste-like resins of Samples 5 and 6 is as follows. To the polyorganosiloxanes A1 and A2 contained in Samples 5 and 6, a platinum catalyst as a catalyst, vinylalkoxysilane as a silane coupling agent, alumina (average particle size 10 μm) as a filler, and H-siloxane (average molecular weight of about 2000, MeHSiO3~5 mol%) as a crosslinking agent were added respectively. Thereby, an adhesive paste was prepared. Alumina (Al2O3) particles (average particle shape 10 μm) were used as a filler for controlling the thermal conductivity and strength. The structures of the polyorganosiloxanes A1 and A2 used in Samples 5 and 6 are as follows. · A1: Vinyl-terminated polydimethylsiloxane (average molecular weight 63,000, phenyl group content 0 mol%) · A2: Vinyl-terminated diphenylsiloxane-dimethylsiloxane copolymer (average molecular weight 60,000, phenyl group content 5.0 mol%) · Polyorganosiloxane A1 or A2: 100 parts by weight · Platinum catalyst: 0.003 parts by weight in terms of platinum content · Silane coupling agent: 2 parts by weight · Filler: 300 parts by weight · Crosslinking agent: 3 parts by weight

[0060] <Evaluation method> · Elastic modulus A test piece with a width of 4 mm was cut out from the film-shaped cured body obtained above, and each test piece was subjected to dynamic viscoelastic analysis (DMA) measurement (in accordance with JIS C6481). The measurement conditions were carried out with a span of 40 mm, applying a tensile load of 1 g in the longitudinal direction of the test piece, imposing a sine wave with an amplitude of 16 μm and a frequency of 11 Hz in the longitudinal direction of the test piece, and measuring the storage elastic modulus (E'). The storage elastic modulus was measured by the above method at temperatures of -50°C, 25°C (room temperature), and 200°C in the chamber. · Coefficient of linear thermal expansion A test piece with a width of 5 mm was cut out from the film-shaped cured body obtained above, and this test piece was subjected to thermomechanical analysis (TMA) measurement (in accordance with JPCA-BU01). The measurement conditions were cooling to -150°C with a span of 15 mm and applying a tensile load of 5 g in the longitudinal direction of the test piece, heating to 300°C at a heating rate of 10°C / min, and measuring the elongation rate ε (ε = ΔL / L0, ε; elongation rate, ΔL; elongation amount, L0; span length) in the range of -100 to 200°C.

[0061] · Adhesion An alumina plate of 100 mm × 25 mm × 1 mm (thickness) and an aluminum plate were bonded together with each paste resin of the above sample forming material so that 12.5 mm overlapped, and a shear tensile test (referring to JISK6850:1999) was carried out at a tensile speed of 2 mm / min, and the fracture surface was confirmed. As an evaluation, cohesive failure was marked as 〇 and interfacial delamination was marked as ×.

[0062] Figure 6 shows the evaluation results of the elastic modulus, coefficient of linear thermal expansion, and adhesiveness of each sample. In Figure 6, the material of Sample 1 is described as (PFPE + silicone)1, the material of Sample 2 is described as (PFPE + silicone)2, and the material of Sample 3 is described as (PFPE + silicone)3. Samples 1 to 3 have a lower elastic modulus than Sample 4 at any of low temperature (-50 °C), room temperature (25 °C), and high temperature (200 °C), and can be said to be softer than Sample 4. Therefore, when stress is generated in the protective member 50 due to the expansion and contraction of each component accompanying the temperature change of the electrostatic chuck 10, compared with Sample 4, it can absorb more stress.

[0063] Regarding the coefficient of linear thermal expansion, the ratios with respect to Sample 5 are 1.0 and 1.3 for Samples 1 and 2, respectively, and the coefficient of linear thermal expansion is close to that of Sample 5. When silicone 1, which is the material of Sample 5, is used as the joint 40 and the materials of Samples 1 and 2 are used as the protective member 50, since the coefficients of linear thermal expansion are close, peeling, cracking, etc. accompanying temperature changes can be suppressed. Also, the ratios with respect to Sample 5 are 0.2 for Sample 3 and 0.03 for Sample 4. Although Sample 3 has a difference in the coefficient of linear thermal expansion from Sample 5 compared with Samples 1 and 2, it can be said that the difference in the coefficient of linear thermal expansion from Sample 5 is significantly smaller compared with Sample 4. Therefore, when silicone 1, which is the material of Sample 5, is used as the joint 40 and the material of Sample 3 is used as the protective member 50, compared with the case of using the material of Sample 4, peeling, cracking, etc. accompanying temperature changes can be sufficiently suppressed.

[0064] Also, regarding the linear thermal expansion coefficient, the ratios for Sample 6 are 1.1 and 1.4 for Samples 1 and 2 respectively, and the linear thermal expansion rate is close to that of Sample 6. When using silicone 2, which is the material of Sample 6, as the joint 40 and using the materials of Samples 1 and 2 as the protective member 50, since the linear thermal expansion rates are close, peeling, cracking, etc. caused by temperature changes can be suppressed. Also, the ratio for Sample 6 is 0.2 for Sample 3 and 0.04 for Sample 4. Although Sample 3 has a difference in linear thermal expansion rate from Sample 6 compared to Samples 1 and 2, it can be said that the difference in linear thermal expansion rate from Sample 6 is significantly smaller compared to Sample 4. Therefore, when using silicone 2, which is the material of Sample 6, as the joint 40 and using the material of Sample 3 as the protective member 50, peeling, cracking, etc. caused by temperature changes can be sufficiently suppressed compared to the case of using the material of Sample 4.

[0065] Also, as shown in FIG. 6, Samples 1 to 3, 5, and Sample 6 have a cohesive failure mode in the adhesion test, indicating good adhesion.

[0066] Samples 1 to 3 satisfy the requirement of [1] below. [1] It contains a matrix resin having a perfluoropolyether backbone and containing a resin component of the same type as the resin adhesive forming the joint 40.

[0067] In addition to the requirement of [1] above, Samples 1 to 3 further satisfy the requirement of [2] below. [2] The ratio of the linear thermal expansion rate of the protective member to the linear thermal expansion coefficient of the resin adhesive forming the joint is 0.1 or more and 2 or less.

[0068] In contrast, Sample 4 does not satisfy either of the requirements of [1] and [2] above.

[0069] Samples 1 to 3 have a matrix resin having a backbone of PFPE with plasma resistance, and Sample 4 also has an epoxy with plasma resistance as the matrix resin. Therefore, Samples 1 to 4 have plasma resistance. Also, as described above, Samples 1 to 3 have silicone in the matrix resin, and it was possible to bring the linear thermal expansion coefficient closer to that of Samples 5 and 6 having silicone as the matrix resin.

[0070] From the results of the above examples, when the joint 40 is formed of the materials of Samples 5 and 6, if the protective member 50 is formed using the materials of Samples 1 to 3, it is considered that the generation of stress due to the difference in linear thermal expansion during temperature change can be suppressed, and the peeling and cracking of the protective member 50 can be suppressed. If the protective member 50 peels off from the joint 40 or cracks occur in the protective member 50, creating a gap between the protective member 50 and the joint 40, plasma reaches the joint 40 through the gap, and the joint 40 is corroded by the plasma. Therefore, when the joint 40 is formed of the materials of Samples 5 and 6, compared with the case where the protective member 50 is formed using the material of Sample 4, using the materials of Samples 1 to 3 can more effectively suppress the plasma exposure of the joint 40 and is considered to be able to suppress the generation of particles.

[0071] As shown in the examples, since the protective member 50 of the above embodiment contains a matrix resin including a resin component of the same type as the resin adhesive forming the joint 40, the linear thermal expansion coefficient can be made closer to that of the protective member 50. That is, when the protective member 50 has a backbone of PFPE and contains a matrix resin including a resin component of the same type as the resin adhesive forming the joint 40, the plasma exposure of the joint 40 can be suppressed even when the temperature change is repeated.

[0072] B. Second Embodiment: FIG. 7 is an explanatory diagram schematically showing a planar configuration of the electrostatic chuck 10A of the second embodiment. In FIG. 7, the positive Z-axis direction is the direction toward the front side of the paper surface. FIG. 8 is an explanatory diagram schematically showing an XZ cross-sectional configuration of the electrostatic chuck 10A. FIG. 8 shows a cross-section taken along line A-A in FIG. 7.

[0073] The electrostatic chuck 10A of the second embodiment includes a plate-like portion 20A instead of the plate-like portion 20 in the electrostatic chuck 10 of the first embodiment, a base portion 30A instead of the base portion 30, and a joint portion 40A instead of the joint portion 40. Further, the electrostatic chuck 10A includes a through-hole protection member 52. In the electrostatic chuck 10A of the second embodiment, the same reference numerals are given to the portions common to the electrostatic chuck 10 of the first embodiment.

[0074] The electrostatic chuck 10A of the present embodiment includes a through-hole 90 extending from the mounting surface S1 of the electrostatic chuck 10A to the lower surface (the surface in the negative Z-axis direction) of the plate-like portion 20A. The through-hole 90 is composed of a through-hole 28 formed in the plate-like portion 20, a through-hole 48 formed in the joint portion 40, and a through-hole 38 formed in the base portion 30. For example, a cooling gas such as helium gas is supplied to the through-hole 90. Thereby, the isothermal property of the wafer W can be improved.

[0075] A through-hole protection member 52 is formed entirely on the inner circumference of the through-hole 48 of the joint portion 40. The through-hole protection member 52 has a PFPE skeleton and contains a matrix resin containing a resin component of the same type as the resin adhesive forming the joint portion 40. For example, the through-hole protection member 52 contains the same matrix resin as the matrix resin of the protection member 50. By doing so, corrosion of the joint portion 40 by plasma or process gas entering the through-hole 90 can be suppressed. Note that the matrix resin of the through-hole protection member 52 does not have to be the same as the matrix resin of the protection member 50. In other embodiments, the through-hole protection member 52 may be formed on a part of the inner circumference of the through-hole 48.

[0076] C. Third Embodiment: FIG. 9 is an explanatory diagram schematically showing a cross-sectional configuration of an electrostatic chuck 10B according to a third embodiment. The electrostatic chuck 10B according to the third embodiment includes a plate-like portion 20B instead of the plate-like portion 20 in the electrostatic chuck 10 of the first embodiment. In the electrostatic chuck 10B of the third embodiment, the same reference numerals are given to the portions common to the electrostatic chuck 10 of the first embodiment.

[0077] The plate-shaped part 20B of this embodiment includes a first plate-shaped part 210 which is a plate-shaped member including a first surface S1 having a substantially circular planar shape, a second plate-shaped part 220 which is a plate-shaped member including a second surface S2 having a substantially circular planar shape with substantially the same diameter as the first plate-shaped part 210, an intermediate joining part 400 disposed between the first plate-shaped part 210 and the second plate-shaped part 220 for joining the first plate-shaped part 210 and the second plate-shaped part 220, an intermediate seal member 600 formed in an annular shape and provided outside the outer peripheral surface 402 of the intermediate joining part 400, and an intermediate protection member 500 which is an annular resin member covering the entire outer peripheral surface 402 of the intermediate joining part 400.

[0078] An adsorption electrode 22 is disposed inside the first plate-shaped part 210, and a heater 24 is disposed inside the second plate-shaped part 220. The first plate-shaped part 210 and the second plate-shaped part 220 may be formed of the same material or different materials. For example, the first plate-shaped part 210 and the second plate-shaped part 220 may be formed mainly of the same material (for example, alumina), and the purity, porosity, and thermal conductivity may be made different. The first plate-shaped part 210 is made into a ceramic substrate with high purity and high density (low porosity) to enhance the plasma resistance, and the second plate-shaped part 220 is made into a ceramic substrate with a lower thermal conductivity than the first plate-shaped part 210, so that the transfer of heat from the heater 24 to the base part 30 can be suppressed.

[0079] The intermediate joint portion 400, the intermediate protective member 500, and the intermediate sealing member 600 each have the same configuration as the joint portion 40, the intermediate protective member 500, and the sealing member 60, respectively. That is, the intermediate protective member 500 has a PFPE skeleton and contains a matrix resin containing a resin component of the same type as the resin adhesive forming the intermediate joint portion 400. By doing so, the linear thermal expansion coefficient of the intermediate protective member 500 can be made closer to that of the intermediate joint portion 400, so that peeling and cracking of the intermediate protective member 500 can be suppressed. Further, corrosion of the intermediate joint portion 400 by plasma can be suppressed by the intermediate protective member 500. Note that the intermediate joint portion 400, the intermediate protective member 500, and the intermediate sealing member 600 do not necessarily have the same configuration as the joint portion 40, the intermediate protective member 500, and the sealing member 60, respectively, and the intermediate protective member 500 only needs to have a PFPE skeleton and contain a matrix resin containing a resin component of the same type as the resin adhesive forming the intermediate joint portion 400.

[0080] In the present embodiment, the first plate-shaped portion 210 is also referred to as the "plate-shaped portion", the second plate-shaped portion 220 is also referred to as the "base portion", the intermediate joint portion 400 is also referred to as the "joint portion", the intermediate protective member 500 is also referred to as the "protective member", and the intermediate sealing member 600 is also referred to as the "sealing member".

[0081] <Modification Example of the Present Embodiment> The present disclosure is not limited to the above-described embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

[0082] · In the above-described embodiments, a single-layer plate-shaped portion (first and second embodiments) and a two-layer plate-shaped portion (third embodiment) are exemplified, but the plate-shaped portion may have three or more layers.

[0083] · In the above-described embodiments, an electrostatic chuck is exemplified as the holding device, but the holding device is not limited to the electrostatic chuck. For example, it can be configured as a heater device, a susceptor, a mounting table, or other plasma processing devices for vacuum devices such as CVD, PVD, and PLD (Pulsed Laser Deposition).

[0084] ·In the above embodiment, an example in which the holding device includes a laminate of plate-like members having a substantially circular plane was shown, but the planar shape is not limited to the above embodiment. For example, a rectangular plane, a polygonal plane, etc. may be used.

[0085] ·The electrostatic chuck may include through holes other than the through holes through which the cooling gas is supplied. For example, a terminal hole for applying a voltage to the adsorption electrode 22, a lift pin hole, etc. may be provided. Also in such a case, by forming a through hole protection member on at least a part of the inner periphery of the through hole penetrating the joint portion, corrosion of the joint portion by plasma or the like through the through hole can be suppressed.

[0086] The present disclosure is not limited to the above-described embodiments and the like, and can be realized in various configurations without departing from the gist thereof. For example, the technical features in the embodiments corresponding to the technical features in each form described in the summary of the invention can be appropriately replaced or combined in order to solve part or all of the above-described problems or to achieve part or all of the above-described effects. Further, if the technical feature is not described as essential in this specification, it can be appropriately deleted.

[0087] The present disclosure can also be realized as the following application examples. [Application Example 1] A holding device for holding an object, A plate-like portion formed in a plate shape, A base portion that supports the plate-like portion and is formed in a plate shape, A joint portion disposed between the plate-like portion and the base portion and made of a resin adhesive that joins the plate-like portion and the base portion, A protection member that covers at least a part of the outer peripheral surface of the joint portion, Comprising The protection member Has a perfluoropolyether skeleton and contains a matrix resin containing a resin component of the same type as the resin adhesive, Holding device. [Application Example 2] The holding device according to Application Example 1, wherein the ratio of the linear thermal expansion coefficient of the protective member to the linear thermal expansion coefficient of the resin adhesive is 0.1 or more and 2 or less, holding device. [Application Example 3] The holding device according to Application Example 1 or Application Example 2, wherein the protective member is chemically bonded to the plate-shaped portion and the base portion, respectively, holding device. [Application Example 4] The holding device according to any one of Application Examples 1 to 3, wherein the protective member further is chemically bonded to the joint portion, holding device. [Application Example 5] The holding device according to any one of Application Examples 1 to 4, having a seal member provided on the outer periphery of the protective member, wherein the protective member and the seal member are in close contact with each other, holding device. [Application Example 6] The holding device according to any one of Application Examples 1 to 5, further comprising a through hole penetrating the joint portion, a through hole protection member having a perfluoropolyether skeleton and containing a matrix resin containing a resin component of the same kind as the resin adhesive, the through hole protection member being formed on at least a part of the inner periphery of the through hole, characterized by comprising holding device.

Explanation of Reference Numerals

[0088] S1... First surface S2... Second surface W... Wafer 10, 10A, 10B... Electrostatic chuck 20, 20A, 20B... Plate-shaped portion 22…Suction electrode 24…Heater 28, 38, 48, 90…Through hole 30, 30A…Base part 32…Refrigerant flow path 40, 40A…Joint part 42, 402…Outer peripheral surface 50…Protective member 52…Through hole protective member 60…Sealing member 210…First plate-like part 220…Second plate-like part 400…Intermediate joint part 500…Intermediate protective member 600…Intermediate sealing member

Claims

1. A holding device for holding an object, comprising: a plate-shaped portion formed in a plate shape; a base portion that supports the plate-shaped portion and is formed in a plate shape; a joint portion disposed between the plate-shaped portion and the base portion and composed of a resin adhesive that joins the plate-shaped portion and the base portion; a protective member that covers at least a part of the outer peripheral surface of the joint portion; and comprising: the protective member: has a perfluoropolyether backbone and contains a matrix resin containing a resin component of the same type as the resin adhesive, characterized in that; holding device.

2. The holding device according to claim 1, characterized in that: the ratio of the linear thermal expansion rate of the protective member to the linear thermal expansion coefficient of the resin adhesive is 0.1 or more and 2 or less. holding device.

3. The holding device according to claim 1, characterized in that: the protective member: is chemically bonded to the plate-shaped portion and the base portion, respectively. holding device.

4. The holding device according to claim 3, characterized in that: the protective member further: is chemically bonded to the joint portion. holding device.

5. The holding device according to claim 1, characterized in that: it has a seal member provided on the outer periphery of the protective member, and the protective member and the seal member are in close contact with each other. holding device.

6. The holding device according to any one of claims 1 to 5, further comprising: a through hole penetrating the joint portion; a through hole protective member that has a perfluoropolyether backbone and contains a matrix resin containing a resin component of the same type as the resin adhesive, and is formed on at least a part of the inner periphery of the through hole. characterized by comprising: holding device. ​

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