Joint body and electrostatic chuck

Abstract

The present invention relates to a joined body and an electrostatic chuck, the joined body is used for joining two materials with different thermal expansion coefficients, and the joined body comprises: a mesh structure made of a material with a first thermal conductivity coefficient; the elastic colloid has a second heat conductivity coefficient and is attached to the net-shaped structure, and the second heat conductivity coefficient is smaller than the first heat conductivity coefficient. The electrostatic chuck comprises the joint body, a metal base and a ceramic plate, the joint body can prevent the joint of the metal base and the ceramic plate from cracking, and the electrostatic chuck has good heat conduction performance.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor equipment, and in particular to a bonding body and an electrostatic chuck. Background Art

[0002] The electrostatic chuck includes a ceramic disc with adsorption and / or heating functions and a metal base with supporting cooling functions. The metal base and the ceramic disc are usually joined together using metal materials such as brazing materials or bonding materials such as organic silicone adhesives. The thermal expansion coefficient of commonly used ceramic materials is quite different from that of the metal base. When heated, the ceramic disc and the metal base are easily cracked due to inconsistent expansion and contraction deformation.

[0003] Metal materials have excellent thermal conductivity. Metal brazing, as a hard connection between the ceramic disk and the metal base, can quickly transfer the heat generated by the ceramic disk to the metal base, but welding is prone to produce residual thermal stress at the interface. When heated, the asynchronous thermal expansion of the ceramic disk and the metal base will aggravate the thermal stress and cause cracking at the joint. Organic thermal conductive adhesives such as silicone can serve as a buffer layer for the inconsistent thermal expansion of ceramics and metals as a soft connection layer, but the thermal conductivity of silicone organic matter is low, especially for operating temperatures above 80°C, the heat transfer effect is not ideal.

[0004] Therefore, there is an urgent need for an electrostatic chuck and bonding body material that can meet the requirements of thermal conductivity and thermal expansion buffering. Summary of the invention

[0005] In order to realize the soft connection between the ceramic disk and the metal base and transfer the heat of the ceramic disk to the metal base in time, the present invention provides a joint body for connecting two materials with different thermal expansion coefficients, and the joint body includes:

[0006] A mesh structure composed of a material with a first thermal conductivity;

[0007] The elastic colloid has a second thermal conductivity and is attached to the mesh structure, wherein the second thermal conductivity is smaller than the first thermal conductivity.

[0008] Preferably, the first thermal conductivity is not less than 100 W / m·K

[0009] Preferably, the mesh structure is made of metal material.

[0010] Preferably, the metal material includes at least one of Al, Cu, Ag, Au, W and Mo.

[0011] Preferably, the elastic colloid is heat-curing silicone.

[0012] Preferably, the elastic colloid is fluorine-containing silicone.

[0013] Preferably, the thickness of the junction body is 20 μm-1000 μm, and preferably, the thickness of the junction body is 50 μm-500 μm.

[0014] In addition, the present invention also provides an electrostatic chuck, comprising:

[0015] the conjugate;

[0016] a metal base having a first coefficient of thermal expansion;

[0017] a ceramic disk having a second coefficient of thermal expansion, the second coefficient of thermal expansion being less than the first coefficient of thermal expansion;

[0018] A sealing ring, sleeved on the outer edge of the joint body, forming a sealed cavity with the metal base and the ceramic disk;

[0019] The joint body is arranged between the metal base and the ceramic disk and is located in the sealed cavity; the upper surface of the mesh structure is in contact with the ceramic disk, and the lower surface of the mesh structure is in contact with the metal base.

[0020] The ceramic disc is internally provided with: an electrostatic adsorption electrode and a heating electrode.

[0021] Preferably, a cooling channel is provided inside the metal base.

[0022] Preferably, the electrostatic chuck further comprises:

[0023] An air hole, the air hole passes through the metal base, the joint body and the ceramic disk;

[0024] A PIN hole passes through the metal base, the joint body and the ceramic disk.

[0025] The present invention adopts a joint body in which a metal wire mesh is embedded in an elastic silicone layer. The metal wire and the silicone surround each other, the silicone bonds the ceramic plate and the metal base, and the mesh is filled with silicone to fix the metal wire mesh. The metal wire mesh serves as a channel for strengthening heat transfer, has a certain thickness, and is in contact with and connected to the surfaces of the ceramic and metal base. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the structure of the electrostatic chuck of the present invention'

[0027] Figure 2-5 Schematic diagrams of mesh structures of junction bodies in different embodiments;

[0028] Figure 6-7 The three-dimensional diagrams are of the mesh structures of the joint bodies of different embodiments;

[0029] Figure 8 It is a schematic diagram of the structure of the joint body of the present invention. DETAILED DESCRIPTION

[0030] The following is a further detailed description of a conjugate and an electrostatic suction cup proposed in the present invention in combination with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the drawings are in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In order to make the purposes, features and advantages of the present invention more obvious and easy to understand, please refer to the accompanying drawings. It should be noted that the structure, proportion, size, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no technical substantive significance. Any modification of the structure, change in the proportional relationship or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope of the technical content disclosed in the present invention.

[0031] In order to achieve a soft connection between two materials with different thermal expansion coefficients, and to solve the problem of cracking at the connection due to inconsistent thermal expansion deformation of the two different materials, the soft connection here refers to a certain elastic deformation ability, which can eliminate the cracking caused by the expansion between the two different materials. The present invention provides a joint body 300, which can connect two materials with different thermal expansion coefficients, and the joint body 300 has the functions of high thermal conductivity and soft connection. Figure 1 The schematic diagram of the structure of an electrostatic chuck is shown. The two materials with different thermal expansion coefficients can be two components of the electrostatic chuck used in semiconductor devices, namely, a metal base 200 and a ceramic plate 100. The material of the ceramic plate 100 can be selected from Al2O3 and AlN, and their thermal expansion coefficients are 6.4×10 -6 / ℃ and 4.5×10 -6 / ℃, the thermal expansion coefficient of the metal base 200 is about 23.2×10 -6 / ℃, which is nearly an order of magnitude different from ceramic materials. When these two materials are connected together, it is easy to cause cracks at the joint due to inconsistent thermal expansion and deformation.

[0032] Figure 1A schematic diagram of the structure of a joint body is shown. A joint body 300 provided in this example includes: a mesh structure 302 and an elastic colloid 301, wherein the thermal conductivity of the elastic colloid 301 is lower than the thermal conductivity of the mesh structure 302. When in use, the mesh structure 302 and the elastic colloid 301 are mixed, specifically, the elastic colloid 301 is filled into the mesh of the mesh structure 302. In this process, the mesh structure 302 can be placed on the surface of the metal base 200, and the elastic colloid 301 is coated on the surface of the metal base 200 to form a joint body 300 with a thickness of 20μm-1000μm, and then the ceramic disk 100 to be joined is placed on the top of the joint body 300, and the joint is completed by curing under vacuum.

[0033] The mesh structure 302 includes various types. Figures 2 to 5 Schematic diagrams showing the mesh structure 302 of different embodiments are shown respectively. Figure 2-5 , the mesh structure 302 may be Figure 2 The square grid shown, Figure 3 and Figure 4 The circular grid shown or Figure 5 The density of the woven mesh shown in the figure can be determined according to the heat conduction requirements. A denser mesh can be used where the heat of the ceramic plate 100 is concentrated, and a sparser mesh can be used where the heat is not concentrated. Figure 3-4 As shown, the circular mesh structure 302 includes a radial skeleton and an annular skeleton, and the density of the mesh can be controlled by changing the positions of the radial skeleton and the annular skeleton. The mesh structure 302 is preferably made of a metal material, which can be selected to include at least one of Al, Cu, Ag, Au, W and Mo. The metal material has a first thermal conductivity, and the first thermal conductivity is not less than 100W / m·K. The elastic colloid 301 is preferably silicone, which can be selected to be fluorine-containing silicone, which has the second thermal conductivity, which is less than the first thermal conductivity. The general second thermal conductivity is 0.1 to 2.5W / m·K. The metal mesh structure 302 can enhance the thermal conductivity of the joint 300. Among them, the fluorine-containing silicone can enhance the resistance to plasma corrosion and increase the service life.

[0034] The thickness of the joint body 300 is mainly determined by the thickness of the mesh structure 302. Figure 6 As shown, the mesh structure 302 is a metal mesh, the wire diameter and thickness of the metal mesh are uniform, and the surface of the planar structure is laid out in a certain grid pattern. Figure 7 As shown, the metal mesh is a three-dimensional structure with convex and concave points, forming a surface with a concave-convex structure. The convex point side 3021 is used to connect to the back of the ceramic plate 100, and the concave point side 3022 is used to connect to the metal base 200. Preferably, the thickness of the joint body 300 is 50μm-500μm.

[0035] In addition, the present invention also provides an electrostatic chuck, please continue to refer to Figure 1 , the electrostatic suction cup includes the joint body 300, the metal base 200, the ceramic disk 100 and the sealing ring 400. Among them, the thermal expansion coefficient of the ceramic disk 100 is smaller than the thermal expansion coefficient of the metal base 200. The soft connection between the ceramic disk 100 and the metal base 200 is realized by the joint body 300, the diameter of the joint body 300 is smaller than the ceramic disk 100, the diameter of the circular joint body 300 is about 0.5mm-10mm smaller than the diameter of the ceramic disk 100, the outer diameter of the joint body 300 is shrunk by 0.25mm-5mm, and the shrunk notch is sealed by the sealing ring 400, that is, the sealing ring 400 is sleeved on the outer edge of the joint body 300, and the upper and lower surfaces of the sealing ring 400 are in close contact with the ceramic disk 100 and the metal base 200 respectively, so that the area where the joint body 300 is located forms a closed space. The ceramic plate 100 is provided with an electrostatic adsorption electrode 101 and a heating electrode 102. The electrostatic adsorption electrode 101 is isolated from the outside and helps the upper surface of the ceramic plate 100 to adsorb the wafer. The heating electrode 102 provides the processing temperature of the wafer. The metal base 200 is provided with a cooling channel 203 to take away the heat transferred from the ceramic plate 100.

[0036] Optionally, the sealing ring 400 is made of fluorine-containing rubber and is used for electrical sealing, insulation and preventing plasma from corroding the joint body 300 .

[0037] Furthermore, the sealing ring 400 is sleeved on the outer edge of the joint body 300 to form a sealed cavity with the metal base 200 and the ceramic disk 100. The joint body 300 is located in the sealed cavity, and the upper surface of the mesh structure of the joint body 300 is in contact with the ceramic disk 100, and the lower surface of the mesh structure is in contact with the metal base 200 to increase the thermal conductivity of the electrostatic suction cup.

[0038] Furthermore, the electrostatic suction cup also includes an air hole 202 and a PIN hole 201. The air hole 202 passes through the He gas flow channel in the metal base 200, the joint body 300 and the ceramic disk 100, and is used to pass helium to transfer heat so that the wafer on the upper surface of the ceramic disk 100 is heated evenly; the PIN hole 201 passes through the metal base 200, the joint body 300 and the ceramic disk 100, and is used for a pin to pass through and lift the wafer.

[0039] The preparation method of the electrostatic chuck is mainly as follows:

[0040] (1) Fix the ceramic plate 100 on the upper pressing plate of the hot press;

[0041] (2) Fix the metal base 200 on the lower pressing plate of the hot press, lay the pre-cut metal wire mesh on the metal base 200, apply a layer of silicone and scrape it flat;

[0042] (3) Evacuate to 1 kPa-80 kPa and press the ceramic plate 100 and the metal base 200 together;

[0043] (4) Heating and curing;

[0044] (5) Clean up a small amount of spilled glue residue.

[0045] The joint body of the present invention contains a metal mesh and elastic silica gel, which provides an excellent buffer layer for the asynchronous thermal expansion of the ceramic disk and the metal base, and at the same time enhances the thermal conductivity of the joint layer;

[0046] In addition, the electrostatic chuck provided by the present invention has excellent thermal conductivity and anti-thermal expansion properties, and promotes the temperature uniformity of the wafer supporting surface.

[0047] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A conjugate, characterized in that: Used to connect two materials with different thermal expansion coefficients, the joint body comprises: A mesh structure composed of a material having a first thermal conductivity; The elastic colloid has a second thermal conductivity and is attached to the mesh structure, wherein the second thermal conductivity is smaller than the first thermal conductivity.

2. The joint body according to claim 1, characterized in that The first thermal conductivity is not less than 100 W / m·K.

3. The joint body according to claim 1, characterized in that: The mesh structure is made of metal material.

4. The joint body according to claim 3, characterized in that: The metal material includes at least one of Al, Cu, Ag, Au, W and Mo.

5. The joint body according to claim 1, characterized in that: The elastic colloid is heat-cured silicone.

6. The joint body according to claim 5, characterized in that: The elastic colloid is fluorine-containing silicone.

7. The joint body according to claim 1, characterized in that: The thickness of the bonded body is 20 μm-1000 μm.

8. The joint body according to claim 7, characterized in that: The thickness of the bonded body is 50 μm-500 μm.

9. An electrostatic chuck, characterized in that: include: The joint body according to any one of claims 1 to 8; a metal base having a first coefficient of thermal expansion; a ceramic disk having a second coefficient of thermal expansion, the second coefficient of thermal expansion being less than the first coefficient of thermal expansion; A sealing ring, sleeved on the outer edge of the joint body, forming a sealed cavity with the metal base and the ceramic disk; The joint body is arranged between the metal base and the ceramic disk and is located in the sealed cavity; the upper surface of the mesh structure of the joint body contacts the ceramic disk, and the lower surface of the mesh structure contacts the metal base. The ceramic disc is internally provided with: an electrostatic adsorption electrode and a heating electrode.

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