Retention device

Abstract

Providing a holding device capable of improving heat extraction performance from an object to be held. 【Solution means】In an electrostatic chuck 1 including a plate-like member 10 (10a, 10b), a base member 20, and a bonding layer 30 that bonds the plate-like member 10 and the base member 20, the plate-like member 10 has a first region R1 at the central portion in the plane direction and a second region R2 at the outer peripheral portion in the plane direction. The bonding layer 30 has a first bonding layer 30a disposed between the base member 20 in the first region R1 and a second bonding layer 30b disposed between the base member 20 in the second region R2. The thermal conductivity of the first bonding layer 30a is greater than the thermal conductivity of the second bonding layer 30b, and the Young's modulus of the first bonding layer 30a is greater than the Young's modulus of the second bonding layer 30b.

Description

Technical Field

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

Background Art

[0002] In the semiconductor manufacturing process, an electrostatic chuck (holding device) is used to hold a semiconductor wafer. As such an electrostatic chuck, one including a ceramic substrate (plate-like member) that holds an object on a mounting surface (holding surface) and a base (base member) joined to the ceramic substrate via a bonding layer is widely known. And, in order to make the temperature distribution on the mounting surface uniform, for example, in the one described in Patent Document 1, the bonding layer is divided into a central portion and its outer peripheral portion, and the thermal conductivity of the bonding layer (second bonding material) in the outer peripheral portion is made higher than the thermal conductivity of the bonding layer (first bonding material) in the central portion.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above-described electrostatic chuck, since the thermal conductivity of the bonding layer in the central portion is lower than the thermal conductivity of the bonding layer in the outer peripheral portion, heat transfer in the central portion becomes worse than heat transfer in the outer peripheral portion. Therefore, at the central portion of the object being held, heat transfer (heat extraction) from the object to the base (base member) deteriorates, and there is a possibility that the temperature of the object cannot be efficiently lowered. That is, there is a possibility that the heat extraction performance from the object to be held deteriorates.

[0005] In recent years, high voltages have been increasingly applied to electrostatic chucks (used at high power). As a result, the temperature of the object to be held becomes higher than before. The higher the temperature of the object, the lower the efficiency of the process treatment for the object. Therefore, there is a demand for heat dissipation performance (improvement of heat dissipation performance) that can reduce the temperature of the object in a short time.

[0006] Therefore, the present disclosure has been made to solve the above-described problems, and an object thereof is to provide a holding device capable of improving the heat dissipation performance from the object to be held.

Means for Solving the Problems

[0007] One aspect of the present disclosure made to solve the above problems is a plate-like member, a base member, and the plate-like member The lower surface and the base member The upper surface and a bonding layer for bonding them, in a holding device comprising: the plate-like member has a central portion in the plane direction The inner part and an outer peripheral portion in the plane direction The outer part and has The inner part and the outer part are separated from each other, the bonding layer has a first bonding layer disposed between the first region and the base member, and a second bonding layer disposed between the second region and the base member, the thermal conductivity of the first bonding layer is greater than the thermal conductivity of the second bonding layer, and the Young's modulus of the first bonding layer is greater than the Young's modulus of the second bonding layer.

[0008] In this holding device, the thermal conductivity of the first bonding layer is made greater than the thermal conductivity of the second bonding layer. Thereby, heat transfer between the plate-like member and the base member in the first region via the first bonding layer can be promoted. Therefore, heat transfer from the object to be held to the plate-like member and the base member is efficiently performed, so that the heat dissipation performance from the object to be held can be improved.

[0009] Further, by making the Young's modulus of the first bonding layer larger than that of the second bonding layer, the second bonding layer can firmly absorb the difference in thermal expansion between the plate-like member and the base member in the outer peripheral portion where the thermal deformation of the base member is likely to be large. Therefore, when thermal deformation occurs in the holding device, the second bonding layer can prevent the occurrence of poor bonding between the base member and the plate-like member in the outer peripheral portion where poor bonding between the base member and the plate-like member is likely to occur.

[0010] In the holding device described above, It is preferable that the first bonding layer is formed separately from the second bonding layer.

[0011] Thus, since the first bonding layer and the second bonding layer are separated in the bonding layer, the arrangement positions of the first bonding layer and the second bonding layer can be freely adjusted in the thickness direction. As a result, the thicknesses of the plate-like members in the first region and the second region can be independently controlled, so that the heat extraction performance from the object to be held can be further improved. In addition, the balance of heat transfer in the first region and the second region can also be adjusted.

[0012] Also, in any of the holding devices described above, It is preferable that the first bonding layer is formed of a bonding material mainly composed of a metal material.

[0013] Thus, by forming the first bonding layer of a bonding material mainly composed of a metal material, the heat transfer between the plate-like member and the base member in the first region can be further promoted. Therefore, since the heat transfer from the object to be held to the plate-like member and the base member is performed more efficiently, the heat extraction performance from the object to be held can be further improved.

[0014] Also, in any of the holding devices described above, The plate-like member is formed of ceramics, It is preferable that the base member is formed of ceramics or a metal-ceramics composite material.

[0015] Thus, by forming the base member from ceramics or a metal-ceramics composite material, the difference in the coefficient of thermal expansion between the plate-like member and the base member can be reduced. Therefore, even when a metal bonding material is used, the plate-like member and the base member can be firmly joined. Accordingly, even when the plate-like member and the base member are joined using a metal bonding material, no joint failure occurs, and as a result, heat transfer from the object to be held to the plate-like member and the base member is efficiently performed, improving the heat extraction performance from the object to be held.

[0016] Also, when the plate-like member and the base member are joined using a resin bonding material, the thickness of the joint layer can be reduced. Therefore, compared with the conventional device, heat transfer from the object to be held to the plate-like member and the base member is promoted, improving the heat extraction performance from the object to be held.

[0017] Also, in any of the holding devices described above, it is preferable that the thickness of the first joint layer is equal to or less than the thickness of the second joint layer.

[0018] When the thickness of the joint layer is thin, the heat extraction performance is improved, and when it is thick, the effect of stress relaxation can be obtained. Therefore, by making the thickness of the first joint layer equal to or less than the thickness of the second joint layer, the heat extraction performance can be improved on the inner side (first joint layer) of the joint layer, and the difference in thermal expansion can be absorbed on the outer side (second joint layer). Accordingly, the effects of improving the heat extraction performance on the inner side (first joint layer) of the joint layer and absorbing the difference in thermal expansion on the outer side (second joint layer) can be further enhanced by controlling the thickness of such a joint layer.

[0019] Also, in any of the holding devices described above, a connection electrode is formed on the surface of the base member, and it is preferable that the connection electrode is electrically connected to the first joint layer.

[0020] In this way, by forming a connection electrode on the surface of the base member, the first bonding layer made of a metal material can be used as a high-frequency electrode, so that the internal electrodes provided in the plate-shaped member can be reduced. As a result, the thickness of the plate-shaped member in the region (first region) where the object is placed can be reduced, and thus the heat dissipation performance can be further improved. In addition, since it is not necessary to provide a through hole for arranging the connection terminal in the base member, the heat uniformity on the holding surface for holding the object can also be improved.

[0021] Note that in order to ensure the insulation of the connection electrode, the connection electrode may be coated with an insulating film formed by spraying or the like.

[0022] Also, in any of the above-described holding devices, the base member is formed by laminating a plurality of members, and it is preferable that the materials of the plurality of members are different.

[0023] In this way, by forming the base member by laminating a plurality of members, a member (for example, a metal-ceramic composite material, etc.) having a small difference in thermal expansion coefficient from the plate-shaped member and a large thermal conductivity can be used for the portion on the surface side in contact with the plate-shaped member, and a member (for example, ceramics, etc.) different from the portion on the surface side in contact with the plate-shaped member can be used for the opposite portion.

[0024] With such a configuration, in addition to improving the heat dissipation performance of the plate-shaped member, the ability to prevent the generation of foreign matter from the through holes (for example, lift pin holes, gas holes, etc.) of the base member can be improved. As a result, contamination in the chamber of the semiconductor manufacturing apparatus using the holding device can be prevented.

[0025] And since the materials of the plurality of members are different, members formed of different materials can be used for the portion on the surface side in contact with the plate-like member and the portion on the opposite side thereof. Therefore, by using a member made of a material with good workability or an inexpensive material for the portion on the side opposite to the surface side in contact with the plate-like member, it is possible to improve the productivity (workability) of the holding device and reduce the manufacturing cost.

[0026] Another aspect of the present disclosure made to solve the above problems is In a holding device including a plate-like member, a base member, and a bonding layer that bonds the plate-like member and the base member, the plate-like member has a first region at the central portion in the plane direction and a second region at the outer peripheral portion in the plane direction, the bonding layer has a first bonding layer disposed between the first region and the base member and a second bonding layer disposed between the second region and the base member, the first bonding layer is formed separately from the second bonding layer, the first bonding layer is formed of a bonding material mainly composed of a metal material and an insulating film is disposed between the first bonding layer and the second bonding layer and is characterized by this.

[0027]

[0028] In this holding device, since the first bonding layer is formed of a metal bonding material, heat transfer between the plate-like member and the base member in the first region can be promoted. Therefore, since heat transfer from the object to be held to the plate-like member and the base member is efficiently performed, the heat extraction performance from the object to be held can be improved.

Advantages of the Invention

[0029] According to the present disclosure, it is possible to provide a holding device capable of improving the heat extraction property from an object to be held.

Brief Description of the Drawings

[0030]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0031] A holding device according to an embodiment of the present disclosure will be described in detail with reference to the drawings. In this embodiment, as the holding device, for example, an electrostatic chuck used in a semiconductor manufacturing device such as an etching device (such as a plasma etching device) or a film forming device (such as a CVD film forming device or a sputtering film forming device) will be exemplified and described.

[0032] Therefore, the electrostatic chuck 1 of this embodiment will be described with reference to FIGS. 1 and 2. The electrostatic chuck 1 of this embodiment is a device that adsorbs and holds a semiconductor wafer W by electrostatic attraction, and is used, for example, to fix the semiconductor wafer W in a vacuum chamber of a semiconductor manufacturing device. As shown in FIGS. 1 and 2, the electrostatic chuck 1 includes a plate-like member 10, a base member 20, and a bonding layer 30 that bonds the plate-like member 10 and the base member 20.

[0033] In the following description, for convenience of explanation, the XYZ axes are defined as shown in FIG. 1. Here, the Z axis is the axis in the axial direction (the vertical direction in FIG. 1) of the electrostatic chuck 1, and the X axis and the Y axis are the axes in the radial direction of the electrostatic chuck 1. Also, the direction of the XY plane is an example of the "plane direction" of the present disclosure.

[0034] As shown in Fig. 1, the plate-shaped member 10 is a disc-shaped member made of ceramics. Specifically, the plate-shaped member 10 has an inner portion 10a located in the first region R1 at the central portion in the XY plane direction (plane direction), and an outer portion 10b located in the second region R2 at the outer peripheral portion in the XY plane direction (plane direction), and the central portion is convex. Then, the semiconductor wafer W is placed on the upper surface 11a of the inner portion 10a (the first region R1) of the plate-shaped member 10, and an annular member (focus ring FR) surrounding the semiconductor wafer W is arranged on the upper surface 11b of the outer portion 10b (the second region R2) of the plate-shaped member 10.

[0035] Note that various ceramics are used as the ceramics forming the plate-shaped member 10. From the viewpoints of strength, wear resistance, plasma resistance, etc., for example, ceramics mainly composed of aluminum oxide (alumina, Al2O3) or aluminum nitride (AlN) are preferably used. Here, the main component means the component with the highest content ratio (for example, the component with a volume content ratio of 90 vol% or more).

[0036] As shown in Figs. 1 and 2, the inner portion 10a of the plate-shaped member 10 is disc-shaped and includes an upper surface 11a which is a holding surface for holding the semiconductor wafer W, and a lower surface 12a provided on the side opposite to the upper surface 11a in the Z-axis direction. The diameter of the inner portion 10a is, for example, about 150 mm to 300 mm. Also, the thickness of the inner portion 10a is, for example, about 1 mm to 10 mm. Note that the thermal conductivity of the inner portion 10a is desirably in the range of 10 W / mK to 50 W / mK (more preferably, 18 W / mK to 33 W / mK).

[0037] As shown in Fig. 2, the inner part 10a of such a plate-like member 10 is provided with a chuck electrode 50 inside thereof. The chuck electrode 50 has, for example, a substantially circular shape when viewed in the Z-axis direction and is formed of a conductive material (for example, tungsten, molybdenum, etc.). A power supply terminal 63 connected to an external power supply (not shown) is electrically connected to the chuck electrode 50 via a via 61 and a terminal pad 62 that are electrically connected. Note that the via 61 and the terminal pad 62 are formed of a conductive material (for example, tungsten, molybdenum, etc.). When a voltage is applied to the chuck electrode 50 from the external power supply via the power supply terminal 63, the terminal pad 62, and the via 61, an electrostatic attraction force (adsorption force) is generated, and the semiconductor wafer W is adsorbed and fixed to the upper surface 11a by this electrostatic attraction force.

[0038] As shown in Figs. 1 and 2, the outer part 10b of the plate-like member 10 is annular and includes an upper surface 11b on which a focus ring FR is disposed and a lower surface 12b provided on the side opposite to the upper surface 11b in the Z-axis direction. The outer diameter of the outer part 10b is, for example, about 180 mm to 400 mm. Also, the thickness of the outer part 10b is, for example, about 1 mm to 10 mm. Note that the thermal conductivity of the outer part 10b is desirably within the range of 10 W / mK to 50 W / mK (more preferably, 18 W / mK to 33 W / mK).

[0039] As shown in Fig. 2, the outer part 10b of such a plate-like member 10 is provided with a chuck electrode 51 inside thereof. The chuck electrode 51 has, for example, a substantially annular shape when viewed in the Z-axis direction and is formed of a conductive material (for example, tungsten, molybdenum, etc.). A power supply terminal 66 connected to an external power supply (not shown) is electrically connected to the chuck electrode 51 via a via 64 and a terminal pad 65 that are electrically connected. When a voltage is applied to the chuck electrode 51 from the external power supply via the power supply terminal 66, the terminal pad 65, and the via 64, an electrostatic attraction force (adsorption force) is generated, and the focus ring FR is adsorbed and fixed to the upper surface 11b by this electrostatic attraction force.

[0040] In addition, the outer portion 10b of the plate-like member 10 is provided with a high-frequency electrode 52 inside thereof. The high-frequency electrode 52 has, for example, a substantially annular shape when viewed in the Z-axis direction, and is formed of a conductive material (for example, tungsten, molybdenum, etc.). A power supply terminal 69 connected to an external power supply (not shown) is electrically connected to the high-frequency electrode 52 via a via 67 and a terminal pad 68 that are electrically connected. Note that the vias 64, 67 and the terminal pads 65, 68 are formed of a conductive material (for example, tungsten, molybdenum, etc.).

[0041] As shown in FIG. 1, the base member 20 is disposed on the lower surface side of the plate-like member 10. The base member 20 is formed, for example, in a columnar shape, and in this embodiment, the portion joined to the first region R1 (inner portion 10a) of the plate-like member 10 is convex. Such a base member 20 is formed of, for example, ceramics (for example, SiC, etc.) or a metal-ceramics composite material (Ti / SiC composite material, MMC (Al / SiC composite material), etc.). Thereby, the difference in thermal expansion coefficient between the base member 20 and the plate-like member 10 can be reduced.

[0042] As shown in FIGS. 1 and 2, the base member 20 includes an upper surface 21a to which the inner portion 10a of the plate-like member 10 is joined and an upper surface 21b to which the outer portion 10b of the plate-like member 10 is joined on the upper surface side, and a lower surface 22 provided on the side opposite to the upper surfaces 21a and 21b in the Z-axis direction. The upper surfaces 21a and 21b of the base member 20 are thermally connected to the lower surface 12a of the inner portion 10a of the plate-like member 10 and the lower surface 12b of the outer portion 10b of the plate-like member 10 via bonding layers 30 (30a, 30b).

[0043] The diameter of the base member 20 is, for example, about 180 mm to 400 mm. The thickness (dimension in the Z-axis direction) of the base member 20 is, for example, about 20 mm to 50 mm. Note that the thermal conductivity of the base member 20 (assuming ceramics or MMC) is desirably in the range of 30 W / mK to 200 W / mK (preferably about 100 W / mK).

[0044] Such a base member 20 is formed with a refrigerant flow path 23 for flowing a refrigerant (for example, a fluorine-based inert liquid, water, etc.). By flowing the refrigerant through the refrigerant flow path 23, the base member 20 is cooled, and the plate-like member 10 is cooled via the bonding layer 30. As a result, the semiconductor wafer W whose temperature has risen during various processings is cooled, and heat extraction (heat removal) from the semiconductor wafer W is performed.

[0045] Further, connection electrodes 70 may be formed on the surface of the base member 20. In the present embodiment, the connection electrodes 70 may be formed on the entire surface of the base member 20 excluding the upper surface 21a. These connection electrodes 70 can be manufactured, for example, by spraying aluminum (cold spray method) to form a film on the surface of the base member 20. These connection electrodes 70 are electrically connected to a first bonding layer 30a described later. Further, a power supply terminal 71 connected to a high-frequency power supply is connected to the connection electrodes 70 on the lower surface 22 side of the base member 20. Note that the connection electrodes 70 only need to be in a shape capable of supplying power to the first bonding layer 30a, and do not necessarily need to be formed on the entire base member 20, may be formed on only a part of the surface of the base member 20, or may be formed in a shape excluding a part from the entire surface of the base member 20.

[0046] And in order to ensure insulation of the connection electrodes 70, the connection electrodes 70 are covered with an insulating film 72. That is, in the present embodiment, since the connection electrodes 70 are formed on the entire surface of the base member 20 excluding the upper surface 21a, the entire surface of the base member 20 excluding the upper surface 21a is covered with the insulating film 72. This insulating film 72 can be formed, for example, by spraying alumina, anodized film, yttria, etc.

[0047] Furthermore, through holes 24, 25, 26 penetrating in the Z-axis direction between the upper surfaces 21a, 21b and the lower surface 22 are formed in the base member 20. These through holes 24, 25, 26 are holes for arranging the power supply terminals 63, 66, 69.

[0048] Note that the base member 20 is also formed with gas holes 15 and 16 for supplying an inert gas (e.g., He gas, etc.) to the minute space between the upper surfaces 11a and 11b of the plate-like member 10 and the held semiconductor wafer W and the focus ring FR, and a through hole that forms part of a lift pin hole 17 for arranging a lift pin for lifting the semiconductor wafer W held on the upper surface 11a.

[0049] As shown in FIGS. 1 and 2, the bonding layer 30 is disposed between the plate-like member 10 and the base member 20 and bonds the plate-like member 10 and the base member 20. This bonding layer 30 has a first bonding layer 30a disposed between the first region R1 (inner portion 10a) of the plate-like member 10 and the base member 20, and a second bonding layer 30b disposed between the second region R2 (outer portion 10b) of the plate-like member 10 and the base member 20.

[0050] As shown in FIG. 2, the first bonding layer 30a is disposed between the lower surface 12a of the inner portion 10a of the plate-like member 10 and the upper surface 21a of the base member 20, and thermally and communicably bonds the inner portion 10a and the base member 20. This first bonding layer 30a is composed of a metal bonding material mainly composed of a metal material. As such a metal bonding material, for example, a metal adhesive bonded using metal powder or metal foil, a metal mesh such as metal fibers, a porous material, a mesh structure, etc. and a brazing material, or a material composed of a plurality of columnar metal pieces and a brazing material can be used. As the metal for forming the metal adhesive, metal mesh or metal pieces, aluminum, indium, titanium, nickel, copper, brass, alloys thereof, or stainless steel, etc. can be used. Note that the phrase "mainly composed of a metal material" means that the metal component is most abundantly contained in the components of the bonding material.

[0051] The thickness (dimension in the Z-axis direction) of this first bonding layer 30a is, for example, about 0.05 mm to 0.5 mm (preferably 0.1 mm to 0.3 mm). The thermal conductivity of the first bonding layer 30a is desirably within the range of, for example, 100 W / mK to 200 W / mK (preferably 150 W / mK to 180 W / mK). Also, the Young's modulus of the first bonding layer 30a is desirably within the range of, for example, 0.5 GPa to 100 GPa (preferably 20 GPa to 80 GPa).

[0052] As shown in FIG. 2, the second bonding layer 30b is disposed between the lower surface 12b of the outer portion 10b of the plate-like member 10 and the upper surface 21b of the base member 20, and thermally joins the outer portion 10b and the base member 20. This second bonding layer 30b is composed of, for example, a resin adhesive such as a silicone-based resin, an acrylic-based resin, or an epoxy-based resin.

[0053] The thickness (dimension in the Z-axis direction) of this second bonding layer 30b is, for example, about 0.05 mm to 0.5 mm (preferably 0.1 mm to 0.5 mm). Also, the thermal conductivity of the second bonding layer 30b is, for example, 1.0 W / mK. Note that the thermal conductivity of the second bonding layer 30b (assuming a silicone-based resin) is desirably within the range of 0.1 W / mK to 2.0 W / mK (preferably 0.5 W / mK to 1.5 W / mK). Also, the Young's modulus of the second bonding layer 30b is desirably within the range of, for example, 0.5 Mpa to 100 MPa (preferably 1 MPa to 10 MPa).

[0054] Also, in this embodiment, in the bonding layer 30, the first bonding layer 30a and the second bonding layer 30b are formed separately. An insulating film 72 is formed in the space portion where the first bonding layer 30a and the second bonding layer 30b are separated. And the thermal conductivity of the first bonding layer 30a is greater than that of the second bonding layer 30b. Also, the Young's modulus of the first bonding layer 30a is greater than that of the second bonding layer 30b. Further, the thickness of the first bonding layer 30a is smaller (thinner) than that of the second bonding layer 30b.

[0055] The electrostatic chuck 1 having the above configuration is manufactured by the following procedure. First, the inner portion 10a of the plate-like member 10 is joined to the upper surface 20a of the base member 20 via the first bonding layer 30a. Next, a connection electrode 70 is formed on the surface of the base member 20. Then, an insulating film 72 is formed on the surface of the base member 20 so as to cover the connection electrode 70. Finally, the outer portion 10b of the plate-like member 10 is joined to the upper surface 21b of the base member 20 (specifically, the insulating film 72 formed on the upper surface 21b) via the second bonding layer 30b. Note that the insulating film 72 is positioned between the first bonding layer 30a and the second bonding layer 30b which are arranged separately. Thereafter, processing and the like are performed on each part, and the electrostatic chuck 1 is completed.

[0056] In such an electrostatic chuck 1 of the present embodiment, the plate-like member 10 has an inner portion 10a located in the first region R1 and an outer portion 10b located in the second region R2. Further, the bonding layer 30 includes a first bonding layer 30a and a second bonding layer 30b, and the inner portion 10a of the plate-like member 10 is joined to the base member 20 via the first bonding layer 30a, and the outer portion 10b of the plate-like member 10 is joined to the base member 20 via the second bonding layer 30b.

[0057] And since the thermal conductivity of the first bonding layer 30a is greater than the thermal conductivity of the second bonding layer 30b, heat transfer between the first region R1 (inner portion 10a) of the plate-like member 10 and the base member 20 via the first bonding layer 30a can be promoted. Therefore, since heat transfer from the semiconductor wafer W to be held to the plate-like member 10 and the base member 20 is efficiently performed, the semiconductor wafer W that has become hot can be efficiently cooled in a short time. That is, the heat extraction performance from the semiconductor wafer W to be held can be improved.

[0058] In addition, since the Young's modulus of the first bonding layer 30a is greater than that of the second bonding layer 20b, in the second region R2 of the plate-like member 10 where the difference in thermal deformation amount between the base member 20 and the plate-like member 10 is likely to be large, the thermal expansion difference between the plate-like member 10 (outer portion 10b) and the base member 20 can be firmly absorbed by the second bonding layer 30b. Therefore, when thermal deformation occurs in the electrostatic chuck 1, generation of a bonding failure between the base member 20 and the plate-like member 10 can be prevented in the second region R2 (outer portion 10b) of the plate-like member 10 where a bonding failure is likely to occur between the base member 20 and the plate-like member 10.

[0059] Furthermore, since the first bonding layer 30a is formed of a bonding material mainly composed of a metal material, heat transfer between the base member 20 can be further promoted in the first region R1 of the plate-like member 10. Thereby, the heat dissipation property from the semiconductor wafer W to be held can be further improved.

[0060] Here, when a metal bonding material is used, if the difference in coefficient of thermal expansion between the plate-like member 10 and the base member 20 is large, there is a risk of a bonding failure when the electrostatic chuck 1 undergoes thermal deformation. Therefore, in the electrostatic chuck 1, the base member 20 is formed of ceramics or a metal-ceramics composite material.

[0061] Therefore, since the difference in coefficient of thermal expansion between the plate-like member 10 and the base member 20 is small, the plate-like member 10 and the base member 20 can be firmly bonded even when a metal bonding material is used for the first bonding layer 30a. Accordingly, it is possible to prevent a bonding failure from occurring between the first region R1 of the plate-like member 10 and the base member 20 due to the first bonding layer 30a using a metal bonding material. As a result, since heat transfer from the semiconductor wafer W to be held to the plate-like member 10 (inner portion 10a) and the base member 20 is efficiently performed, the heat dissipation property from the semiconductor wafer W can be improved.

[0062] In addition, since the difference in the coefficient of thermal expansion between the plate-like member 10 and the base member 20 is small, even if the thickness of the second bonding layer 30b that bonds the second region R2 of the plate-like member 10 and the base member 20 is reduced, no bonding failure occurs. Therefore, since the thickness of the second bonding layer 30b using a resin bonding material can be reduced, heat transfer from the focus ring FR and the semiconductor wafer W to be held to the plate-like member 10 and the base member 20 is promoted as compared with the conventional device. As a result, the heat dissipation property of the electrostatic chuck 1 can be further improved.

[0063] And in the bonding layer 30, since the first bonding layer 30a and the second bonding layer 30b have a separate structure, the first bonding layer and the second bonding layer are separated. Therefore, in the Z-axis direction, the arrangement positions of the first bonding layer 30a and the second bonding layer 30b can be freely adjusted. As a result, since the thickness of the first region R1 (inner portion 10a) of the plate-like member 10 can be reduced, the heat dissipation property from the semiconductor wafer W to be held can be further improved. Also, in the plate-like member 10, the balance of heat transfer in the first region R1 and the second region R2 can be adjusted.

[0064] Also, the thickness of the first bonding layer 30a is equal to or less than the thickness of the second bonding layer 30b. Since the heat dissipation property is improved when the thickness of the bonding layer is thin and the effect of stress relaxation can be obtained when the thickness is thick, heat dissipation can be improved inside the bonding layer 30 (first bonding layer 30a), and the difference in thermal expansion can be absorbed outside (second bonding layer 30b). In this way, by controlling the thickness of the bonding layer 30 (first bonding layer 30a and second bonding layer 30b), the effect of improving heat dissipation in the first bonding layer 30a located inside the bonding layer 30 and absorbing the difference in thermal expansion in the second bonding layer 30b located outside can be further enhanced.

[0065] Furthermore, in the electrostatic chuck 1, a connection electrode 70 is formed on the surface of the base member 20, and the connection electrode 70 is electrically connected to the first bonding layer 30a. And a power supply terminal 71 connected to a high-frequency power supply is connected to the connection electrode 70 on the lower surface 22 side of the base member 20.

[0066] As a result, the first bonding layer 30a can be used as a high-frequency electrode. Therefore, the number of internal electrodes provided in the first region R1 of the plate-like member 10 can be reduced. Accordingly, since the thickness of the portion of the plate-like member 10 (i.e., the inner portion 10a) located in the region (first region R1) where the semiconductor wafer W is placed can be made thinner, the heat dissipation property from the semiconductor wafer W can be further improved. Also, since there is no need to provide a through hole for arranging the power supply terminal in the base member 20, the heat uniformity on the upper surface 11a for holding the semiconductor wafer W can be improved.

[0067] As described above, according to the electrostatic chuck 1 of the present embodiment, the bonding layer 30 includes the first bonding layer 30a and the second bonding layer 30b, and the thermal conductivity of the first bonding layer 30a is greater than that of the second bonding layer 30b. Therefore, heat transfer between the base member 20 and the first region R1 of the plate-like member 10 via the first bonding layer 30a can be promoted. Accordingly, heat transfer from the semiconductor wafer W to be held to the plate-like member 10 and the base member 20 is efficiently performed, so that the heat dissipation property from the semiconductor wafer W can be improved. As a result, the temperature of the semiconductor wafer W that has become high can be lowered in a short time.

[0068] Further, since the Young's modulus of the first bonding layer 30a is greater than that of the second bonding layer 30b, in the second region R2 of the plate-like member 10 where the difference in thermal deformation from the base member 20 is likely to be large, the difference in thermal expansion between the plate-like member 10 (outer portion 10b) and the base member 20 can be firmly absorbed by the second bonding layer 30b. Therefore, when thermal deformation occurs in the electrostatic chuck 1, the occurrence of bonding failure between the base member 20 and the plate-like member 10 (outer portion 10b) can be prevented in the second region R2 of the plate-like member 10 where bonding failure is likely to occur between the base member 20.

[0069] <Modification Example> Next, a modification of the above embodiment will be described with reference to FIG. 3. This modification has the same basic configuration as the above embodiment, but is different in that it is composed of a plurality of members having different base member materials. Therefore, the same components as those in the above embodiment are denoted by the same reference numerals and their description is omitted, and the description will focus on the differences.

[0070] In the electrostatic chuck 1a according to the modification, as shown in FIG. 3, the base member 120 includes a first base member 121 and a second base member 122. The first base member 121 and the second base member 122 are joined and integrated by a base bonding layer 123. That is, the base member 120 is formed by laminating a plurality of members.

[0071] The first base member 121 is formed of a member having the same material as the base member 20 in the above embodiment (for example, ceramics (such as SiC, etc.) or a metal-ceramics composite material (Ti / SiC composite material, MMC (Al / SiC composite material), etc.). On the other hand, the second base member 122 is formed of a member having the same material as the plate-like member 10 in the above embodiment (for example, ceramics mainly composed of aluminum oxide (alumina, Al2O3) or aluminum nitride (AlN), etc.).

[0072] And the plate-like members 10 (the first plate-like member 10a and the second plate-like member 10b) are joined to the upper surface side of the first base member 121. That is, similar to the above embodiment, the first base member 121 having a small difference in thermal expansion coefficient from the plate-like member 10 and a large thermal conductivity is joined to the plate-like member 10. Therefore, the heat extraction performance of the plate-like member 10 can be improved, and the occurrence of poor bonding between the plate-like member 10 and the base member 20 can be prevented.

[0073] On one side, a second base member 122, which is made of a material different from that of the first base member 121 and is formed of a material with excellent corrosion resistance, is joined to the lower surface side of the first base member 121. Although the MMC alone has sufficient corrosion resistance, by forming the second base member 122 with ceramics that are more excellent in corrosion resistance, it is possible to prevent the generation of foreign matter from the through holes (for example, gas holes 15, lift pin holes 17, etc.) of the base member 120. Therefore, it is possible to prevent contamination in the chamber of a semiconductor manufacturing apparatus using the electrostatic chuck 1a.

[0074] Also, in the base member 120, by using a member made of a material with good workability and low cost (for example, alumina, etc.) for the second base member disposed on the side opposite to the upper surface side in contact with the plate-like member 10, it is possible to improve the productivity (workability) of the electrostatic chuck 1a and reduce the manufacturing cost.

[0075] According to the electrostatic chuck 1a according to the modification example in this way, the base member 120 is formed by laminating a plurality of members (the first base member 121, the second base member 122). For the first base member 121, a member with a small difference in thermal expansion coefficient from the plate-like member 10 and a large thermal conductivity is used, and for the second base member 122, a member made of a material with excellent corrosion resistance, good workability, and low cost is used. Thereby, in addition to improving the heat extraction property of the plate-like member 10, it is possible to prevent the generation of foreign matter from the through holes (for example, gas holes 15, lift pin holes 17, etc.) of the base member 120. Also, it is possible to improve the productivity (workability) of the electrostatic chuck 1a and reduce the manufacturing cost.

[0076] Note that the above embodiments are merely examples and do not limit the present disclosure in any way. It goes without saying that various improvements and modifications are possible without departing from the gist thereof. For example, in the above embodiment, as the plate-like member 10, the case where the inner portion 10a and the outer portion 10b have a separate structure and are separated from each other is exemplified, but the present disclosure can also be applied when the inner portion 10a and the outer portion 10b are integrated.

[0077] In the above-described embodiment, the case where the first bonding layer 30a is formed of a metal bonding material has been exemplified. However, the first bonding layer 30a is not limited to a metal bonding material as long as its thermal conductivity and Young's modulus are greater than those of the second bonding layer 30b. For example, the first bonding layer 30a can also be formed of a resin bonding material having a higher thermal conductivity and Young's modulus than the second bonding layer. When the first bonding layer 30a is composed of a resin adhesive, for example, a silicone-based resin, an acrylic-based resin, an epoxy-based resin, or the like can be used. Also, by changing the amount of filler added, the thermal conductivity and Young's modulus of the first bonding layer 30a can be made greater than those of the second bonding layer 30b.

[0078] In the above-described embodiment, the case where the second bonding layer 30b is formed of a resin bonding material has been exemplified. However, the second bonding layer 30b is not limited to a resin bonding material as long as its thermal conductivity and Young's modulus are smaller than those of the first bonding layer. For example, the second bonding layer 30b can also be formed of a metal bonding material having a lower thermal conductivity and Young's modulus than the first bonding layer 30a. When the second bonding layer 30b is composed of a metal bonding material, for example, aluminum, indium, titanium, nickel, copper, brass, these alloys, or stainless steel can be used.

[0079] Furthermore, in the above-described embodiment, the case where the connection electrode 70 is formed on the surface of the base member 20 has been exemplified. However, when the base member 20 has conductivity (for example, when the base member is formed of metal or MMC), the connection electrode 70 does not have to be formed. This is because when the base member 20 has conductivity, the base member 20 and the first bonding layer 30a can be electrically connected.

Explanation of Reference Numerals

[0080] 1 Electrostatic chuck 10 Plate-like member 10a Inner part 10b Outer part 20 Base member 30 Bonding layer 30a First bonding layer 30b Second bonding layer 70 Connection electrode 120 Base member 121 First base member 122 Second base member 123 Base bonding layer FR Focus ring R1 First region R2 Second region W Semiconductor wafer

Claims

In a holding device comprising a plate-like member, a base member, and a bonding layer that bonds the plate-like member and the base member, the plate-like member has a first region at the central portion in the plane direction and a second region at the outer peripheral portion in the plane direction, the bonding layer has a first bonding layer disposed between the first region and the base member and a second bonding layer disposed between the second region and the base member, the first bonding layer is formed separately from the second bonding layer, the first bonding layer is formed of a bonding material mainly composed of a metal material, an insulating film is disposed between the first bonding layer and the second bonding layer, the main components of the bonding materials are different between the first bonding layer and the second bonding layer, the thickness of the first bonding layer is equal to or less than the thickness of the second bonding layer A holding device characterized by the above.

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