JP2024019807A - Retainer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for suppressing warpage of a plate-like part in a retainer that holds an object.

SOLUTION: A retainer includes: a plate-like part formed in a plate-like having a first surface on a side where an object is mounted and a second surface as a back surface of the first surface; a plate-like base part that is arranged on the second surface side of the plate-like part, and has a cooling function; and a first bonding part that is arranged between the plate-like part and the base part, and bonds the plate-like part and the base part. The plate-like part includes: a first plate-like part including the first surface; a second plate-like part including the second surface; and a second bonding part that is arranged between the first plate-like part and the second plate-like part, and bonds the first plate-like part with the second plate-like part. A heat resistance of the second bonding part is 6.5×10^-4(m²K/W) or less at 120°C.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a holding device for holding an object.

For example, an electrostatic chuck is used as a holding device for holding an object such as a wafer when manufacturing semiconductors. The electrostatic chuck includes a plate portion on which an object is placed, a base portion that cools the plate portion, and a joint portion that joins the plate portion and the base portion. An electrostatic chuck is equipped with a chuck electrode placed inside a plate-like member, and utilizes electrostatic attraction generated by applying a voltage to the chuck electrode to attach the surface of the plate-like member (hereinafter referred to as " (Also referred to as "suction surface.") Objects such as wafers are attracted and held there.

If the temperature of the wafer held on the suction surface of the electrostatic chuck does not reach the desired temperature, the precision of each process (film formation, etching, etc.) on the wafer may decrease. The ability to control distribution is required. Therefore, by heating with a heater, which is a resistance heating element placed inside the plate-shaped part, and cooling by supplying refrigerant to the refrigerant flow path formed in the base member, the temperature distribution on the adsorption surface of the plate-shaped part is improved. control (and in turn, control of the temperature distribution of the wafer held on the suction surface).

Conventionally, the controllability of the temperature distribution on the surface (adsorption surface) that holds the wafer has been improved by adjusting the resistance value of the resistance heating element. However, in an electrostatic chuck, the temperature distribution of the suction surface that holds the wafer depends not only on the accuracy of the heater (resistance heating element) but also on the accuracy of the base and joint parts. There has been a problem in that the controllability of the temperature distribution of the suction surface that holds the wafer cannot be sufficiently improved just by adjusting it.

To solve this problem, a plate-shaped part is constructed by joining a second plate-shaped part having a heater formed by a resistance heating element and a first plate-shaped part having a chuck electrode, and the variation in resistance value of the heater can be reduced. A technique has been proposed for suppressing the temperature distribution and improving the controllability of the temperature distribution of the suction surface that holds the wafer (for example, see Patent Document 1).

Patent No. 6867556

By the way, when an electrostatic chuck is used in an environment where it is exposed to strong plasma energy or where high power is input to the electrostatic chuck, the suction surface tends to become hot. The electrostatic chuck described in the above-mentioned Patent Document 1 has a first plate-like part and a second plate-like part joined by an adhesive, and since the thermal conductivity of the adhesive is generally relatively low, the above-mentioned Patent Document If the electrostatic chuck described in No. 1 is used in an environment where the suction surface tends to reach a high temperature, the transfer of heat from the plate portion to the base portion may be suppressed, and the suction surface may not be sufficiently cooled. Therefore, it is desired to improve the heat dissipation of the joint where the first plate-like part and the second plate-like part are joined. In addition, there is room for improvement in terms of heat conduction from the heater to the first plate-like part as well with respect to the joint where the first plate-like part and the second plate-like part are joined.

Such problems are not limited to electrostatic chucks, but also include heater devices for vacuum devices such as CVD (chemical vapor deposition), PVD (physical vapor deposition), and PLD (pulsed laser deposition), susceptors, and holding devices such as mounting tables. to This is a common issue.

The present invention has been made in order to solve the above-mentioned problems, and provides a holding device for holding an object on a plate-like part in which a first plate-like part and a second plate-like part are joined. It is an object of the present invention to provide a technique for improving thermal conductivity between a first plate-like part and a second plate-like part.

The present invention has been made to solve the above-mentioned problems, and can be realized as the following forms.

(1) According to one embodiment of the present invention, a holding device for holding an object is provided. This holding device includes a plate-shaped portion having a first surface on which the object is placed and a second surface that is the back surface of the first surface; a plate-shaped base portion disposed on the second surface side and having a cooling function; a first plate-shaped base portion disposed between the plate-shaped portion and the base portion and joining the plate-shaped portion and the base portion; a joint portion, and the plate-like portion includes a first plate-like portion including the first surface, a second plate-like portion including the second surface, and the first plate-like portion and the second plate-like portion. a second joint part that is disposed between the first plate part and the second plate part, and the second joint part has a thermal resistance of 120 degrees Celsius. It is 6.5×10 ⁻⁴ (m ² K/W) or less.

For example, in an environment where the holding device is exposed to strong plasma energy, the first surface of the plate-shaped portion tends to reach a high temperature. If the temperature of the first surface of the plate-like part is 120°C, for example, if the thermal resistance is within the above range, good heat conduction from the first plate-like part to the second plate-like part can be achieved. Therefore, it is possible to improve the transfer of heat from the first plate-like part to the base part, and it is possible to cool the first surface of the plate-like part well.

(2) In the holding device of the above embodiment, the thermal resistance of the second joint portion may be 5.5×10 ⁻⁴ (m ² K/W) or less at −60° C. As described above, when the first surface of the plate-like part is used under conditions where the first surface is likely to reach a high temperature (for example, 120°C), the base part may be used at an extremely low temperature of -60°C or lower. In such a case, by setting the thermal resistance of the second joint within the above range, the first surface of the plate-shaped portion can be rapidly cooled.

(3) In the holding device of the above embodiment, the thermal conductivity of the material constituting the first plate portion may be higher than the thermal conductivity of the material constituting the second plate portion. In order to transfer the heat of the first surface of the plate-like part to the base part, it is preferable that the heat conductivity of the plate-like part is high. However, for example, when the second plate-like part is equipped with a heater, the temperature distribution on the first surface of the plate-like part is adjusted by the heater, but if the thermal conductivity of the second plate-like part is too high, the base part (cooling ), and it may be difficult to adjust the temperature distribution on the first surface of the plate-shaped portion using a heater. Therefore, if the thermal conductivity of the first plate part is made higher than the thermal conductivity of the second plate part, even if the second plate part is equipped with a heater, the temperature distribution on the first surface of the plate part can be adjusted appropriately. can be adjusted to

(4) In the holding device of the above embodiment, the first joint portion may have a thermal resistance of 6.5×10 ⁻⁴ (m ² K/W) or less at 120° C. In this way, heat conduction from the plate part to the base part can also be improved, so heat transfer from the plate part to the base part can be further improved, and the first surface of the plate part can be improved. Cooling properties can be further improved.

(5) In the holding device of the above embodiment, the thickness of the second joint portion may be less than or equal to the thickness of the first joint portion. In the holding device, the difference in thermal expansion between the first plate portion and the second plate portion constituting the plate portion is often small. On the other hand, since the base part has a cooling function, it is often made of a material with a high thermal conductivity (for example, a material whose main component is metal), and therefore often has a high coefficient of thermal expansion. Therefore, it is preferable that the thickness of the first joint part is large enough to exhibit stress relaxation ability based on the difference in thermal expansion between the plate-like part and the base part. On the other hand, as mentioned above, the difference in thermal expansion between the first plate part and the second plate part is often small, and the stress relaxation ability of the second joint part is less important than that of the first joint part. There is no problem even if the thickness of the second joint part is less than the thickness of the first joint part. When the thickness of the second joint is less than or equal to the thickness of the first joint, the stress due to the difference in thermal expansion between the plate part and the base part is alleviated by the first joint, and the thermal resistance of the second joint is reduced. (reducing the thickness), it is possible to improve heat conduction from the plate-like part to the base part.

Note that the present invention can be realized in various forms, such as a semiconductor manufacturing apparatus including a holding device, a method for manufacturing a holding device, and a method for forming a bonding portion.

FIG. 1 is a perspective view schematically showing the external configuration of an electrostatic chuck according to a first embodiment. FIG. 2 is an explanatory diagram schematically showing an XZ cross-sectional configuration of an electrostatic chuck. It is a figure showing the thermal conductivity of each material. It is a figure showing the thermal resistance of a sample. It is a figure showing the thermal resistance of a sample. FIG. 7 is an explanatory diagram schematically showing an XZ cross-sectional configuration of an electrostatic chuck according to a second embodiment. FIG. 7 is an explanatory diagram schematically showing an XZ cross-sectional configuration of an electrostatic chuck according to a third embodiment.

<First embodiment>
FIG. 1 is a perspective view schematically showing the external configuration of an electrostatic chuck 10 according to the first embodiment. FIG. 2 is an explanatory diagram schematically showing the XZ cross-sectional configuration of the electrostatic chuck 10. In FIGS. 1 and 2, XYZ axes that are orthogonal to each other are shown in order to specify the direction. In FIG. 2, the positive Y-axis direction is the direction toward the back side of the page. In this specification, for convenience, the positive Z-axis direction is referred to as an upward direction, and the negative direction of the Z-axis is referred to as a downward direction, but the electrostatic chuck 10 is actually installed in a different direction. may be done. The electrostatic chuck 10 in this embodiment is also referred to as a "holding device".

The electrostatic chuck 10 is a device that attracts and holds an object (for example, a wafer W) by electrostatic attraction, and is used, for example, to fix the wafer W in a vacuum chamber of a semiconductor manufacturing apparatus. The electrostatic chuck 10 includes plate-like parts 100 arranged side by side in the vertical direction (Z-axis direction), a base part 200, and a first joint part 400 that joins the plate-like part 100 and the base part 200. .

The plate-shaped portion 100 is a plate-shaped member having a first surface S1 and a second surface S2 that is the back surface of the first surface S1. Specifically, the plate-like portion 100 includes a first plate-like portion 110 (FIG. 1), which is a plate-like member including a first surface S1 having a substantially circular planar shape, and a substantially circular plate-like member having approximately the same diameter as the first plate-like portion 110. The second plate portion 120 (FIG. 1) is a plate member including a circular planar second surface S2 (FIG. 2), and is arranged between the first plate portion 110 and the second plate portion 120. , a second joint portion 150 that joins the first plate portion 110 and the second plate portion 120.

Inside the first plate-shaped portion 110, an adsorption electrode 130 (FIG. 2) made of a conductive material (for example, tungsten, molybdenum, etc.) is arranged. The shape of the attraction electrode 130 when viewed in the Z-axis direction is, for example, approximately circular. When a voltage is applied to the attraction electrode 130 from a power source (not shown), electrostatic attraction is generated, and the wafer W (FIG. 1) is attracted and fixed to the first surface S1 of the first plate-shaped portion 110 by this electrostatic attraction. be done. That is, the first surface S1 of the first plate-shaped portion 110 functions as a mounting surface on which the wafer W is mounted. The shape of the adsorption electrode 130 is not limited to this embodiment, and may be, for example, a spiral shape.

A spiral heater 140 (FIG. 2) is arranged inside the second plate-shaped portion 120 when viewed in the Z-axis direction. As illustrated, the heater 140 is disposed on the surface (fourth surface S4) of the second plate-shaped portion 120 opposite to the second surface S2. In this embodiment, the heater 140 is a metallized layer made of tungsten, molybdenum, or the like. The shape of the heater 140 is not limited to this embodiment, and may be, for example, a disk shape. In other embodiments, the plate-shaped portion 100 may not include the heater 140.

The plate-shaped portion 100 is a dense body whose main component is ceramics (eg, alumina, aluminum nitride, etc.) called so-called fine ceramics or new ceramics. In the present specification, when a specific component "is the main component" or "is the main forming material", it means that the content of the specific component is 50% by volume or more. In other embodiments, the plate-shaped portion 100 may be formed mainly of a material other than ceramic, such as resin such as polyimide, or transparent glass, for example.

Although the thermal conductivity of the plate-like part 100 is not particularly limited, it is preferable that the thermal conductivity of the material forming the first plate-like part 110 is greater than or equal to the thermal conductivity of the material forming the second plate-like part 120. . It is more preferable that the thermal conductivity of the material forming the first plate portion 110 is higher than the thermal conductivity of the material forming the second plate portion 120.

The thermal conductivity of the first plate-like part 110 can be calculated by measuring the thermal diffusivity and specific heat of a sample cut out from the first plate-like part 110 using a laser flash method. By keeping the measurement temperature constant using a constant temperature bath or the like, it is possible to measure the thermal conductivity at each temperature. The measurement temperature may be, for example, 25° C. (room temperature), which is the general operating temperature of the electrostatic chuck 10. The same applies to the thermal conductivity of the second plate-shaped portion 120, the second joint portion 150, and the first joint portion 400.

The thermal conductivity of the first plate-like part 110 and the second plate-like part 120 can be adjusted by adjusting the type of ceramic as the main component, the type of filler, content, porosity, etc.

The first plate portion 110 and the second plate portion 120 that constitute the plate portion 100 may be formed of the same material or may be formed of different materials. In this embodiment, the first plate-like part 110 and the second plate-like part 120 are formed using the same material (for example, alumina) as a main component, and have different purity, porosity, and thermal conductivity. In other words, the same material system is used, but the physical properties are changed. As described above, the first plate portion 110 includes the first surface S1, and the wafer W is placed thereon. Therefore, the first plate portion 110 is exposed to plasma during etching or cleaning of the wafer W, and therefore requires plasma resistance. Therefore, the first plate portion 110 is required to have high density. Furthermore, since the first surface S1 of the first plate-like portion 110 easily becomes high in temperature due to heat input from the plasma, the first plate-like portion 110 requires high thermal conductivity. Therefore, the purity of the ceramics is increased. That is, the first plate-shaped portion 110 is a ceramic substrate with high purity and high density (low porosity).

On the other hand, the second plate-shaped portion 120 is a plate-shaped member in which the heater 140 is disposed. The heater 140 is arranged on the surface (fourth surface S4) of the second plate-shaped portion 120 opposite to the second surface S2. Since the heater 140 adjusts the temperature distribution on the first surface S1 of the first plate-shaped portion 110, it is preferable that the amount of heat transferred from the heater 140 to the base portion 200 is small. Therefore, it is preferable that the material forming the second plate-like part 120 has a lower thermal conductivity than the material forming the first plate-like part 110. Therefore, low thermal conductivity can be achieved by, for example, mixing a ceramic sintering aid. For example, a glass with a low melting point (for example, an oxide of Si, Ca, Mg, etc.) is mixed into the alumina base material. As a result, the second plate portion 120 is easier to sinter than the first plate portion 110, and costs can be reduced. In addition, since the first plate-like part 110 has high purity and high density, the cost is high, so it is preferable to reduce the cost of the second plate-like part 120. That is, the constituent material of the first plate-like part 110 has higher purity and higher thermal conductivity than the constituent material of the second plate-like part 120, and the first plate-like part 110 has a higher density ( (low porosity) is preferable. In addition, when changing the physical properties of the first plate-like part 110 and the second plate-like part 120 using different materials, for example, the first plate-like part 110 may be formed mainly of aluminum nitride, which has high thermal conductivity. The second plate-shaped portion 120 may be formed mainly of alumina, which has a lower thermal conductivity than aluminum nitride.

The diameter of the first surface S1 of the first plate portion 110 is, for example, about 50 mm to 500 mm (usually about 200 mm to 350 mm). In this specification, descriptions using "~" for numerical ranges include lower and upper limits unless otherwise specified. For example, the description "10 to 20" includes both the lower limit value of "10" and the upper limit value of "20". That is, "10 to 20" has the same meaning as "10 or more and 20 or less".

The second joint portion 150 is a plate member on a substantially circular plane having the same diameter as the third surface S3 of the first plate portion 110 and the fourth surface S4 of the second plate portion 120. 110 and the second plate-like portion 120 are joined. The second joint 150 is made of, for example, an adhesive whose main component is an organic material such as acrylic or polyimide, silicone, glass, metal, or the like. The second joint portion 150 may contain filler such as ceramic powder.

The thermal resistance of the second joint portion 150 is preferably 6.5×10 ^-4 (m ² K/W) or less, and 5.0×10 ^-4 (m ² K/W) or less at 120° C. It is more preferable that The thermal resistance of the second joint 150 is R2 (m ² K/W), the thickness of the second joint 150 is t2 (m), and the thermal conductivity of the constituent material of the second joint 150 is λ2 (W/mK). Then, the thermal resistance R2 of the second joint portion 150 is determined by the following (Formula 1).
R2 (m ² K/W) = t2 (m) ÷ λ2 (W/mK) ... (Formula 1)

For example, in an environment where the electrostatic chuck 10 is exposed to strong plasma energy, the first surface S1 of the first plate-shaped portion 110 tends to reach a high temperature. For example, if the temperature of the first surface S1 of the first plate part 110 is 120° C., and the thermal resistance is within the above range, the temperature from the first plate part 110 to the second plate part 120 increases. Since the heat conduction can be improved, the transfer of heat from the first plate-shaped part 110 to the base part 200 can be improved, and the first surface S1 of the plate-shaped part 100 can be cooled well. I can do it. That is, it is possible to suppress a decrease in responsiveness of heat generation and/or cooling in the plate-like part 100 due to the presence of the second joint part 150, and to improve the temperature distribution on the first surface S1 of the plate-like part 100. Deterioration of controllability can be suppressed.

The thermal resistance of the second joint is preferably 5.5×10 ^-4 (m ² K/W) or less, and 4.0×10 ^-4 (m ² K/W) or less at -60°C. More preferably, it is 3.5×10 ⁻⁴ (m ² K/W) or less. As described above, when the electrostatic chuck 10 is used in an environment where it is exposed to strong plasma energy or where high power is input to the electrostatic chuck 10, the first surface S1 of the plate-shaped portion 100 is heated to a high temperature. easy to become. In the case of usage conditions such that the first surface S1 of the plate-shaped portion 100 is, for example, 120° C., the temperature of the refrigerant supplied to the base portion 200 is set to, for example, −100° C. in order to cool the plate-shaped portion 100. It may be about ℃. When the base part 200 becomes low temperature, the second joint part 150 also becomes low temperature, so by setting the thermal resistance of the second joint part 150 at -60° C. to the above value, the temperature of the base part 200 is reduced to an extremely low temperature (for example, −100° C.), heat transfer between the base portion 200 and the first plate portion 110 via the second joint portion 150, that is, heat transfer from the first plate portion 110 to the base portion 200. The cooling efficiency of the electrostatic chuck 10 can be improved. When the second bonding part 150 includes an adhesive made of resin, the thermal conductivity of the adhesive generally decreases as the temperature rises. That is, when the thickness of the second joint portion 150 is kept constant, the thermal resistance tends to increase as the temperature rises. If the thermal resistance of the second joint part 150 at -60°C is set to the above value, sufficient cooling performance can be obtained even if the temperature of the second joint part 150 becomes higher than -60°C. Therefore, the cooling rate of the surface (first surface S1) on which the object is placed can be improved.

The thickness of the second joint part 150 is not particularly limited, but is preferably equal to or less than the thickness of the first joint part 400. The first plate-like part 110 and the second plate-like part 120 that constitute the plate-like part 100 are formed of, for example, a material whose main component is ceramic, and the difference in thermal expansion between them is often small. On the other hand, since the base part 200 has a cooling function, it is often formed from a material with high thermal conductivity, for example, a material whose main component is metal (described in detail later). Therefore, the coefficient of thermal expansion of the base part 200 is relatively large, and the difference in coefficient of thermal expansion between the second plate part 120 and the base part 200 is due to the thermal expansion coefficient between the first plate part 110 and the second plate part 120. It is often larger than the expansion rate difference. Therefore, it is preferable that the first joint portion 400 has a thickness that exhibits the ability to relax stress based on the difference in thermal expansion. On the other hand, as described above, the difference in thermal expansion between the first plate portion 110 and the second plate portion 120 is often small, and the stress relaxation ability of the second joint portion 150 is more important than that of the first joint portion 400. Therefore, there is no problem even if the thickness of the second joint part 150 is equal to or less than the thickness of the first joint part 400. When the thickness of the second joint part 150 is set to be less than or equal to the thickness of the first joint part 400, the stress based on the difference in thermal expansion between the plate-shaped part 100 and the base part 200 is relaxed by the first joint part 400, and the second joint part 150 By reducing the thermal resistance of (reducing the thickness), it is possible to improve heat conduction from the plate-shaped portion 100 to the base portion 200.

The thickness of the first joint 400 and the second joint 150 can be measured by the following method.
The electrostatic chuck 10 is cut out with a cutter at a cut plane perpendicular to the first surface S1 (for example, the XZ plane in FIG. 1), and the cross section is observed and measured using a magnifying glass or a microscope that can measure the length. Here, the cut plane passes through the center of the first surface S1. Observe the central part of the cross section (corresponding to the center of the third surface S3 and the second surface S2), the end part, and the intermediate position (radius / 2) in a 1.5 mm width range, and check the convex part in each range. The thicknesses of the recessed portions are measured, and the average values are calculated and used as the thickness of the first joint portion 400 and the thickness of the second joint portion 150, respectively.

The base portion 200 is a substantially circular planar plate member having a larger diameter than the plate portion 100 . The base portion 200 may include a material with high thermal conductivity, for example, at least one metal selected from aluminum, magnesium, molybdenum, titanium, tungsten, and nickel. Molybdenum, titanium, and tungsten have relatively small coefficients of thermal expansion among the above-mentioned metals, so when forming the base portion 200 using at least one of these metals, it is necessary to It is desirable to be able to suppress the difference in thermal expansion coefficient between the two. In addition, in this specification, "coefficient of thermal expansion" refers to "coefficient of linear expansion." Further, since magnesium has a relatively small Young's modulus, it is desirable to use magnesium to configure the base portion 200 because thermal stress generated in the base portion 200 can be reduced. Additionally, aluminum has relatively high thermal conductivity, is easy to process, and is low cost. Therefore, when the base portion 200 is configured using aluminum, it is desirable because the cooling efficiency of the plate-like portion 100 and the wafer W by the base portion 200 can be increased, and the manufacturing cost of the electrostatic chuck 10 can be suppressed. . From the viewpoint of suppressing manufacturing costs while increasing the cooling efficiency of the base part 200, it is desirable that the content ratio of metal in the base part 200 is high, and it is desirable that the base part 200 has metal as a main component. For example, it is desirable to contain 90% by mass or more of aluminum, which has high versatility (for example, to be composed of an aluminum alloy such as A6061 or A5052). However, the base portion 200 may include components other than metal, such as ceramic. The diameter of the base portion 200 is, for example, approximately 220 mm to 550 mm (usually 220 mm to 350 mm), and the thickness of the base portion 200 is, for example, approximately 20 mm to 40 mm.

A refrigerant flow path 210 (FIG. 2) is formed inside the base portion 200. When processing the wafer W held by the plate-shaped portion 100 of the electrostatic chuck 10 using plasma, heat is input to the wafer W from the plasma, and the temperature of the wafer W increases. When a refrigerant (for example, a fluorine-based inert liquid, water, liquid nitrogen, etc.) is flowed through the refrigerant channel 210 formed in the base part 200, the base part 200 is cooled. The plate-like part 100 is cooled by heat transfer between the base part 200 and the plate-like part 100 via the first joint part 400 and the second joint part 150, and is held on the first surface S1 of the plate-like part 100. The wafer W is cooled down. Thereby, temperature control of the wafer W is realized. In other embodiments, the base portion may not have internal coolant channels and may be cooled from the outside.

The first joining part 400 is a substantially circular planar plate member having the same diameter as the plate part 100, and joins the plate part 100 and the base part 200. The first bonding section 400 is formed from an adhesive, and for example, an adhesive whose main component is acrylic, organic material such as polyimide, silicone, etc. can be used.

A silicone adhesive can be produced, for example, by mixing polydimethylsiloxane containing a curable functional group, a crosslinking agent, a silane coupling agent, a curing catalyst, and a filler. At least one of alumina, silica, aluminum nitride, boron nitride, carbon black, graphite, carbon nanotubes, silicon carbide, silicon nitride, iron oxide, and magnesium oxide can be used as the filler. A sheet-like or varnish-like silicone adhesive can be used to join the plate-like part 100 and the base part 200. When used in a sheet form, after cutting into a predetermined shape, a sheet silicone adhesive is applied to each of the plate part 100 and the base part 200 in a vacuum. Furthermore, the plate-shaped part 100 and the base part 200 are bonded together in a vacuum via a sheet-shaped silicone adhesive, and the plate-shaped part 100 and the base part 200 are bonded by curing at a temperature of 100° C. or higher. be able to. When using a varnish-like silicone adhesive, it is applied to the base part 200 by screen printing, bonded to the plate-shaped part 100 in a vacuum, and cured at a temperature of 100° C. or higher, thereby bonding the plate-shaped part 100 and the base. 200 can be joined. Here, a resin wall may be formed on the base portion 200 to prevent the resin from flowing out.

The thermal resistance of the first joint portion 400 may be 6.5×10 ⁻⁴ (m ² K/W) or less at 120° C. In this way, heat removal performance can be improved. The first joint portion 400 may be formed of the same material as the second joint portion 150. The thermal resistance of the first joint 400 is R1 (m ² K/W), the thickness of the first joint 400 is t1 (m), and the thermal conductivity of the constituent material of the first joint 400 is λ1 (W/mK). Then, the thermal resistance R1 of the first joint portion 400 is determined by the following (Formula 2).
R1 (m ² K/W) = t1 (m) ÷ λ1 (W/mK) ... (Formula 2)

The thickness of the first joint portion 400 is not particularly limited, but is preferably 200 μm to 800 μm. It is better for the first joint portion 400 to be thin in terms of heat dissipation, but if it is too thin, the difference in thermal expansion between the plate-like portion 100 and the base portion 200 cannot be alleviated. When the thickness of the first joint portion 400 is within the above range, heat can be removed appropriately and the difference in thermal expansion between the plate portion 100 and the base portion 200 can be alleviated.

The thermal conductivity of the first joint portion 400 and the second joint portion 150 can be adjusted by adjusting the type of adhesive, the type of filler, and the ratio. For example, thermally conductive fillers (eg, alumina, aluminum nitride, boron nitride, etc.) can be added to increase thermal conductivity.

The method for manufacturing the electrostatic chuck 10 is not particularly limited, but it can be manufactured, for example, by the method described in Japanese Patent No. 6867556, a patent filed by the applicant of the present application.
The outline is as follows.
First, the first plate-like part 110 and the second plate-like part 120 are produced, and the second plate-like part 120 and the base part 200 are joined by the first joint part 400.

First, a plurality of ceramic green sheets are produced, and a predetermined processing is performed on a predetermined ceramic green sheet. Examples of the predetermined processing include printing of metallized paste for forming the suction electrode 130 and the like, and drilling processing. A laminate of ceramic green sheets is produced by stacking these ceramic green sheets, thermocompression bonding, and processing such as cutting. The first plate-shaped portion 110 is obtained by firing the produced laminate of ceramic green sheets. Note that, if necessary, the first plate-shaped portion 110 may be subjected to warpage correction, surface polishing, etc.

Next, a heater pattern is formed using the material for forming the heater 140 on a predetermined ceramic green sheet. A cover layer made of an insulating material and covering the heater pattern is disposed on the ceramic green sheet. The second plate-shaped portion 120 in which the heater 140 is disposed is manufactured by firing a laminate in which a plurality of ceramic green sheets including the ceramic green sheet are laminated.

Then, the second plate portion 120 and the base portion 200 are joined by the second joint portion 150, and the cooling mechanism of the base portion 200 performs cooling (supply of refrigerant to the refrigerant channel 210) and power supply to the heater 140. While performing these steps, the temperature distribution on the fourth surface S4 of the second plate-shaped portion 120 is measured. Based on the temperature distribution measurement results, the electrical resistance (heat amount) of the heater 140 is adjusted by removing a portion of the heater 140 covered with the cover layer along with the cover layer. Thereafter, the second plate part 120 and the first plate part 110 are joined by the second joint part 150 .

As described above, in the method for manufacturing the electrostatic chuck 10 of the present embodiment, the base part 200 is cooled by the cooling mechanism while the base part 200 is joined to the second plate-like part 120 on which the heater 140 is disposed. While supplying power to the heater 140, the temperature distribution on the fourth surface S4 of the second plate-shaped portion 120 is measured, and based on the temperature distribution measurement result, a portion of the heater 140 covered with the cover layer is removed with the cover layer. By removing it, the electrical resistance (heat amount) of the heater 140 is adjusted, and then the first plate part 110 is joined to the second plate part 120. That is, in the method for manufacturing the electrostatic chuck 10 of the present embodiment, after manufacturing the part closer to the base part 200 (lower side) than the heater 140, the part is placed in the same state as in actual use (i.e., the part is not connected to the coolant flow path 210). The temperature distribution of the fourth surface S4 of the second plate-shaped portion 120 is measured in a state in which the refrigerant is supplied and the power is supplied to the heater 140), and the electrical resistance of the heater 140 ( (calorific value) can be adjusted. Therefore, according to the method of manufacturing the electrostatic chuck 10 of the present embodiment, the electric resistance (heat amount) of the heater 140 can be adjusted accurately in a short time, and as a result, the first surface of the plate-shaped portion 100 Controllability of the temperature distribution of S1 can be improved. Note that, in this specification, the term "high controllability of the temperature distribution on the first surface S1 of the plate-shaped portion 100" includes the meaning that the temperature distribution on the entire first surface S1 is nearly uniform.

As explained above, according to the electrostatic chuck 10 of the present embodiment, the thermal resistance of the second joint portion 150 is 6.5×10 ⁻⁴ (m ² K/W) or less at 120° C. , it is possible to improve the heat conduction from the first plate-shaped part 110 to the second plate-shaped part 120, so that the transfer of heat from the first plate-shaped part 110 to the base part 200 can be improved, The first surface S1 of the plate-shaped portion 100 can be cooled well.

The present disclosure will be explained in more detail with reference to Examples. Here, samples A to E were formed as a plurality of second joint portions 150 with different thicknesses using materials having different thermal conductivities (material Nos. 1 to 6), and the thermal resistance was calculated.

Material No. The adhesives (resin materials) and fillers in Nos. 1 to 6 are as follows.
Material 1: Silicone resin containing phenyl group filled with filler containing aluminum nitride powder (44 vol%)
Material 2: Silicone resin containing phenyl groups is highly filled with alumina filler (44 vol%)
Material 3: Silicone resin filled with filler containing aluminum nitride powder (44 vol%)
Material 4: Highly filled silicone resin with alumina filler (44 vol%)
Material 5: Silicone resin filled with alumina filler (20vol%)
Material 6: Silicone resin, no filler Here, by including an appropriate amount of phenyl group in the side chain of the silicone resin, steric hindrance increases, hinders crystallization, and lowers the glass transition temperature (Tg). I can do it. In other words, flexibility at low temperatures can be imparted.

FIG. 3 is a diagram showing the thermal conductivity of each material. The example shown in FIG. 3 shows the results of measuring thermal conductivity at -100°C, -60°C, -40°C, -20°C, 25°C, 70°C, 120°C, 160°C, and 180°C. Thermal conductivity was measured by hot wire method. Thermal conductivity was directly measured by forming a block of each material, sandwiching a thermocouple and a heater between the blocks, and measuring the temperature rise in response to heat input to the heater. The thermal conductivity at each temperature was measured by keeping the measurement temperature constant using a constant temperature bath or the like. In FIG. 3, locations marked with "-" indicate that no measurements were made. In Samples 1 to 6, the higher the temperature, the lower the thermal conductivity tended to be.

Sheet-like samples with different thicknesses were produced using each of the above materials. The sample name is the code corresponding to the thickness + material number. Indicated by The codes corresponding to the thicknesses are as follows.
A: 0.20mm, B: 0.30mm, C: 0.35mm, D: 0.40mm, E: 0.50mm
For example, the sample name of a sample made of material 1 and having a thickness of 0.2 mm is A1.

The method for producing the sheet-like sample is as follows. In addition to the resin material (100 parts by weight) and inorganic filler as the adhesive before curing, a platinum catalyst (0.003 parts by weight in terms of platinum content), a silane coupling agent (2 parts by weight), and a crosslinking agent (3 parts by weight). A paste-like resin composition (adhesive paste) was prepared by stirring the constituent materials (parts by weight) under vacuum using a vacuum defoaming stirrer and then kneading them with a three-roll mill. Thereafter, the prepared adhesive paste was spread on a polyethylene terephthalate (PET) film using a doctor blade. Next, the PET film spread with the adhesive paste is cut, and then the adhesive paste with the cut PET film is heated in a dryer at an appropriately set temperature and time. Adhesive sheets as each sample were produced by curing or curing.

FIG. 4 shows the thermal resistance of samples with thicknesses of 0.20 mm, 0.30 mm, and 0.35 mm, and FIG. 5 shows the thermal resistance of samples with thickness of 0.40 mm and 0.50 mm.
As shown in the figure, (1) The thermal resistance of samples C2, C4, D2, D4, E1, and E3 is 6.5×10 ⁻⁴ (m ² K/W) or less at 120° C. (2) The thermal resistance of samples A1 to A4, B1 to B4, C1, C3, C4, D1, and D3 is 4.0×10 ^-4 (m ² K/W) or less at -60°C. (3) The thermal resistance of samples A1 to A4, B1 to B4, C1, C3, D1, and D3 is 5.0×10 ⁻⁴ (m ² K/W) or less at 120° C.

Using the samples shown in FIGS. 4 and 5, the temperature of the first surface S1 of the plate-shaped portion 100 when the electrostatic chuck 10 of the first embodiment is configured was simulated. The simulation was performed using a one-dimensional steady heat conduction equation under the conditions of the first plate-like part 110 having a thickness of 3.0 mm, the second plate-like part 120 having a thickness of 1.5 mm, and a plasma heat input of 5000 W.

In the sample as shown in (1) above, the thermal resistance is 6.5×10 ^-4 (m ² K/W) or less at 120°C, and thus an electrostatic chuck is constructed using the second joint 150. Then, when the temperature of the refrigerant supplied to the base portion 200 was 25° C., the temperature of the first surface S1 of the plate-like portion 100 could be controlled to 140° C. or lower. Further, the thermal resistance of the sample shown in (3) above is 5.0×10 ⁻⁴ (m ² K/W) or less at 120° C. In this way, the temperature of the first surface S1 of the plate-shaped portion 100 could be controlled to 120° C. or less. Further, the thermal resistance of the sample shown in (2) above is 4.0×10 ^-4 (m ² K/W) or less at -60°C. In this way, when the temperature of the refrigerant supplied to the base part 200 is set to an extremely low temperature of -100°C, the temperature of the first surface S1 of the plate-like part 100 can be controlled to be -20°C or lower. was completed.

<Second embodiment>
FIG. 6 is an explanatory diagram schematically showing the XZ cross-sectional configuration of the electrostatic chuck 10A of the second embodiment. The electrostatic chuck 10A of this embodiment differs from the electrostatic chuck 10 of the first embodiment in that the plate-like portion 100A has a three-layer structure. Specifically, the first plate-like portion 110A has a two-layer structure. In the embodiment described below, the same components as the electrostatic chuck 10 are denoted by the same reference numerals, and the preceding description is referred to.

The first plate-like part 110A includes a third plate-like part 113, a fourth plate-like part 114, and a third joint part 115 that joins the third plate-like part 113 and the fourth plate-like part 114. . In this embodiment, the third plate-like part 113 and the fourth plate-like part 114 are made of the same material as the first plate-like part 110 of the first embodiment. Further, the third joint portion 115 is preferably formed of the same material as the second joint portion 150 and preferably has substantially the same thermal resistance as the second joint portion 150. It is further preferable that the third joint part 115, the second joint part 150, and the first joint part 400 are formed of the same material. Even in this case, the same effects as in the first embodiment can be obtained.

<Third embodiment>
FIG. 7 is an explanatory diagram schematically showing the XZ cross-sectional configuration of the electrostatic chuck 10B of the third embodiment. The electrostatic chuck 10B of this embodiment differs from the electrostatic chuck 10A of the second embodiment in the configuration of the plate-shaped portion 100B. Specifically, the first plate-like part 110 has a single layer like the first embodiment, and the second plate-like part 120B has a two-layer structure. In the embodiment described below, the same components as the electrostatic chuck 10 are denoted by the same reference numerals, and the preceding description is referred to.

The second plate-like part 120B includes a fifth plate-like part 125, a sixth plate-like part 126, and a fourth joint part 127 that joins the fifth plate-like part 125 and the sixth plate-like part 126. . The fifth plate portion 125 includes a first heater 141 , and the sixth plate portion 126 includes a second heater 142 . In this way, the temperature of the first surface S1 of the plate-shaped portion 100B can be controlled more precisely. In this embodiment, the fifth plate-like part 125 and the sixth plate-like part 126 are formed of the same material as the second plate-like part 120 of the first embodiment. Further, the fourth joint portion 127 is preferably formed of the same material as the second joint portion 150 and preferably has substantially the same thermal resistance as the second joint portion 150. It is further preferable that the fourth joint part 127, the second joint part 150, and the first joint part 400 are formed of the same material. Even in this case, the same effects as in the first embodiment can be obtained.

<Modification of this embodiment>
The present invention is not limited to the above-described embodiments, and can be implemented in various forms without departing from the spirit thereof. For example, the following modifications are also possible.

- In the above embodiment, a plate-like part with a two-layer structure and a plate-like part with a three-layer structure are illustrated, but the plate-like part may have four or more layers. Even in the case of four or more layers, the same effect as in the above embodiment can be obtained by making the joint part that joins each layer (plate) constituting the plate-shaped part similar to the second joint part in the above embodiment. I can do it.

- In the above embodiment, an example was shown in which the object is held on the first surface S1 of the plate-shaped part 100, but another ceramic substrate is bonded on top of the plate-shaped part 100, and A configuration may also be used in which the object is held.

- In the above embodiment, an electrostatic chuck is illustrated as a holding device, but the holding device is not limited to an electrostatic chuck. For example, it can be configured as a heater device, a susceptor, or a mounting table for a vacuum device such as CVD, PVD, or PLD (Pulsed Laser Deposition).

- In the above embodiment, an example was shown in which the holding device includes a stack of plate-like members having a substantially circular plane, but the planar shape is not limited to the above embodiment. For example, it may be a rectangular plane, a polygonal plane, or the like.

The present disclosure is not limited to the above-described embodiments, examples, and modifications, and can be realized in various configurations without departing from the spirit thereof. For example, the technical features in the embodiments corresponding to the technical features in each form described in the summary column of the invention may be used to solve some or all of the above-mentioned problems, or to achieve one of the above-mentioned effects. In order to achieve some or all of the above, it is possible to replace or combine them as appropriate. Further, unless the technical feature is described as essential in this specification, it can be deleted as appropriate.

The present disclosure can also be realized as the following application examples.
[Application example 1]
A holding device for holding an object,
a plate-shaped portion having a first surface on which the object is placed and a second surface that is the back surface of the first surface;
a plate-shaped base part disposed on the second surface side of the plate-shaped part and having a cooling function;
a first joint part that is disposed between the plate-like part and the base part and joins the plate-like part and the base part;
Equipped with
The plate-shaped portion is
a first plate-shaped portion including the first surface;
a second plate-shaped portion including the second surface;
a second joint part disposed between the first plate part and the second plate part and joining the first plate part and the second plate part;
has
The thermal resistance of the second joint is 6.5×10 ⁻⁴ (m ² K/W) or less at 120° C.,
holding device.
[Application example 2]
The holding device according to claim 1,
The second joint portion has a thermal resistance of 5.5×10 ⁻⁴ (m ² K/W) or less at −60° C.,
holding device.
[Application example 3]
The holding device according to claim 1 or claim 2,
The thermal conductivity of the material constituting the first plate-like part is higher than the thermal conductivity of the material constituting the second plate-like part,
holding device.
[Application example 4]
The holding device according to any one of claims 1 to 3,
The first joint portion has a thermal resistance of 6.5×10 ⁻⁴ (m ² K/W) or less at 120° C.;
holding device.
[Application example 5]
The holding device according to any one of claims 1 to 4,
The thickness of the second joint part is less than or equal to the thickness of the first joint part,
holding device.
[Application example 6]
The holding device according to any one of claims 1 to 5,
A heater is arranged on a side of the second plate-shaped part opposite to the second surface,
holding device.

S1...first surface S2...second surface W...wafer 10, 10A, 10B...electrostatic chuck 100, 100A, 100B...plate-like part 110...first plate-like part, 110A...first plate-like part 113...third Plate-shaped part 114...Fourth plate-shaped part 115...Third joint part 120...Second plate-shaped part, 120B...Second plate-shaped part 125...Fifth plate-shaped part 126...Sixth plate-shaped part 127...Fourth joint Part 130...Adsorption electrode 140, 141, 142...Second heater 150...Second joint part 200...Base part 210...Refrigerant channel 400...First joint part S3...Third surface S4...Fourth surface

Claims (6)

A holding device for holding an object,
a plate-shaped portion having a first surface on which the object is placed and a second surface that is the back surface of the first surface;
a plate-shaped base part disposed on the second surface side of the plate-shaped part and having a cooling function;
a first joint part that is disposed between the plate-like part and the base part and joins the plate-like part and the base part;
Equipped with
The plate-shaped portion is
a first plate-shaped portion including the first surface;
a second plate-shaped portion including the second surface;
a second joint part disposed between the first plate part and the second plate part and joining the first plate part and the second plate part;
has
The thermal resistance of the second joint is 6.5×10 ⁻⁴ (m ² K/W) or less at 120° C.,
holding device. The holding device according to claim 1,
The second joint portion has a thermal resistance of 5.5×10 ⁻⁴ (m ² K/W) or less at −60° C.,
holding device. The holding device according to claim 2,
The thermal conductivity of the material constituting the first plate-like part is higher than the thermal conductivity of the material constituting the second plate-like part,
holding device. The holding device according to claim 3,
The first joint portion has a thermal resistance of 6.5×10 ⁻⁴ (m ² K/W) or less at 120° C.;
holding device. The holding device according to claim 4,
The thickness of the second joint part is less than or equal to the thickness of the first joint part,
holding device. The holding device according to any one of claims 1 to 5,
A heater is arranged on a side of the second plate-shaped part opposite to the second surface,
holding device.

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