Holding member

Abstract

To provide a holding member that can suppress the occurrence of temperature singularities in the object being held.SOLUTION: In one embodiment of the present disclosure, a holding member 10 for holding a semiconductor wafer W includes a base portion 41 and a surface layer 51 that is located on the side of the base portion 41 that holds the semiconductor wafer W, and at least a portion of which is exposed to the surface, and the material that constitutes the surface layer 51 has a lower degree of crystallinity than the material that constitutes the base portion 41.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a holding member for holding an object. [Background technology]

[0002] Patent Document 1 discloses an electrostatic chuck having a ceramic insulating layer made of an aerosol deposition film, which is a layer including a convex portion that supports a semiconductor wafer as an object to be held and a surface layer portion underneath the convex portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7214867 Summary of the Invention [Problem to be solved by the invention]

[0004] In the electrostatic chuck disclosed in Patent Document 1, there may be some locations where excessive heat transfer is likely to occur due to a structure below the ceramic insulating layer (for example, an electrostatic electrode between the ceramic dielectric layer and the ceramic base material, etc.), which makes it difficult to control the temperature of the semiconductor wafer placed on the ceramic insulating layer, and there is a risk of temperature singularities occurring in the semiconductor wafer.

[0005] Therefore, the present disclosure has been made to solve the above-mentioned problems, and aims to provide a holding member that can suppress the occurrence of temperature singularities in an object to be held. [Means for solving the problem]

[0006] One form of the present disclosure made to solve the above problems is characterized in that a holding member for holding an object has a base portion and a surface layer portion that is provided on the side holding the object relative to the base portion and at least a portion of which is exposed to the surface, and the material constituting the surface layer portion has a lower degree of crystallinity than the material constituting the base portion.

[0007] According to this embodiment, the crystallinity of the material constituting the surface layer is reduced, thereby reducing the thermal conductivity of the surface layer. Therefore, even if the base member has a portion where excessive heat transfer is likely to occur due to internal structures (e.g., gas flow paths, electrodes, etc.), the surface layer with low thermal conductivity provided between the object and the base member prevents excessive heat transfer in that portion and ensures uniform heat transfer overall. Therefore, the occurrence of temperature singularities in the held object can be suppressed.

[0008] In the above aspect, it is preferable that the X-ray diffraction pattern of the surface layer portion has at least one diffraction peak with a half-width of 3° or more at a diffraction angle 2θ of 40° or more, or has a halo pattern derived from an amorphous material at a diffraction angle 2θ in the range of 0° or more and less than 40°.

[0009] According to this aspect, the thermal conductivity of the surface layer can be more reliably reduced.

[0010] In the above aspect, the surface layer has a holding surface provided on the side that holds the object, and a convex portion formed to protrude from the holding surface toward the side that holds the object and for placing the object, and it is preferable that the material that constitutes the convex portion has a lower degree of crystallinity than the material that constitutes the base portion.

[0011] According to this aspect, since the crystallinity of the material constituting the convex portions is low, it is possible to suppress the occurrence of particle shedding due to friction between the convex portions and the object.

[0012] In the above aspect, it is preferable that the surface layer portion is made of the same material as the base material portion.

[0013] According to this embodiment, the thermal expansion coefficient of the surface layer portion can be made equal to that of the base portion, thereby preventing problems caused by the difference in thermal expansion coefficient (for example, problems such as the surface layer portion peeling off from the base portion during thermal expansion).

[0014] In the above aspect, the surface layer is preferably formed of an ion-assisted vapor deposition film.

[0015] According to this aspect, the surface layer is formed of an ion-assisted vapor deposition film having high adhesion, thereby improving adhesion between the surface layer and the substrate. [Effects of the Invention]

[0016] The holding member of the present disclosure can suppress the occurrence of temperature singularities in the object being held. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic perspective view of an electrostatic chuck. [Figure 2] FIG. 2 is a schematic diagram of the electrostatic chuck taken along an XZ cross section. [Figure 3] FIG. 1 is a schematic plan view of an electrostatic chuck. [Figure 4] FIG. 2 is an XZ cross-sectional view of the holding member. [Figure 5] FIG. 1 is a diagram showing an X-ray diffraction pattern of an alumina substrate. [Figure 6] FIG. 10 is a diagram showing an X-ray diffraction pattern of a film formed by ion-assisted deposition at a temperature of 300° C. [Figure 7] FIG. 10 is a diagram showing an X-ray diffraction pattern of a film formed by ion-assisted deposition at a temperature of 150° C. DETAILED DESCRIPTION OF THE INVENTION

[0018] A holding member according to the present disclosure will be described. In this embodiment, an electrostatic chuck used in a semiconductor manufacturing apparatus such as a film forming apparatus (such as a CVD film forming apparatus or a sputtering film forming apparatus) or an etching apparatus (such as a plasma etching apparatus) will be described as an example of a holding device having the holding member.

[0019] <Explanation of electrostatic chuck> First, the electrostatic chuck 1 of this embodiment will be described.

[0020] The electrostatic chuck 1 is a device that attracts 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. The semiconductor wafer W is an example of the "target object" in this disclosure.

[0021] In the following description, for convenience of explanation, the X, Y, and Z axes are defined as shown in Fig. 1. Here, the Z axis is an axis in the axial direction of the electrostatic chuck 1 (the vertical direction in Fig. 1), and the X and Y axes are axes in the radial direction of the electrostatic chuck 1.

[0022] As shown in FIGS. 1 and 2, the electrostatic chuck 1 includes a holding member 10, a base member 20, and a bonding layer 30 that bonds the holding member 10 and the base member 20 together.

[0023] The holding member 10 is a disk-shaped member and has a holding surface 11 (upper surface) that holds the semiconductor wafer W, and a lower surface 12 that is provided on the opposite side of the holding surface 11 in the thickness direction of the holding member 10 (i.e., the Z-axis direction).

[0024] The holding surface 11 of the holding member 10 has an uneven shape. Specifically, as shown in FIGS. 2 to 4, the holding surface 11 is provided with an annular protrusion 13 on its outer periphery (more specifically, near the outer edge) for placing the semiconductor wafer W. The annular protrusion 13 is formed in an annular shape along the outer periphery of the holding surface 11 and protrudes toward the side that holds the semiconductor wafer W. The annular protrusion 13 is also called a seal band and is an example of the "protrusion" in the present disclosure.

[0025] Furthermore, a plurality of columnar pin-shaped protrusions 14 for placing the semiconductor wafer W are provided on the holding surface 11, protruding toward the side that holds the semiconductor wafer W, on the inner side of the annular protrusion 13. In this way, the holding surface 11 is provided with the annular protrusion 13 that is arranged so as to surround all of the plurality of pin-shaped protrusions 14. The pin-shaped protrusions 14 are an example of a "protrusion" in the present disclosure.

[0026] As shown in Fig. 3, each pin-shaped protrusion 14 has a substantially circular shape when viewed in the Z-axis direction (plan view) and is arranged at substantially equal intervals. Note that, as shown in Figs. 2 to 4, the portion of the holding surface 11 inside the annular protrusion 13 where no pin-shaped protrusion 14 is provided is a recess 15.

[0027] The semiconductor wafer W is supported by the annular protrusion 13 and the multiple pin-shaped protrusions 14 on the holding surface 11 of the holding member 10 and is held by the electrostatic chuck 1. When the semiconductor wafer W is held by the electrostatic chuck 1, a space S exists between the surface (lower surface) of the semiconductor wafer W and the holding surface 11 of the holding member 10 (more specifically, the recessed portion 15 of the holding surface 11) (see FIGS. 2 and 4). An inert gas for heat transfer (e.g., helium gas) is supplied to this space S from a gas hole 17 opening in the holding surface 11 via a gas tunnel 16 provided in the holding member 10.

[0028] A chuck electrode 18 is disposed inside the holding member 10. The electrostatic chuck 1 is configured to hold the semiconductor wafer W on the holding surface 11 by supplying power to the chuck electrode 18 to generate an electrostatic attractive force.

[0029] Further details of the holding member 10 will be described later.

[0030] As shown in Figures 1 and 2, the base member 20 is disposed on the side opposite the holding surface 11 of the holding member 10. The base member 20 is formed, for example, in a cylindrical shape. The base member 20 is formed, for example, from a metal (e.g., aluminum or an aluminum alloy), but may be formed from a material other than metal. The base member 20 is thermally connected to the lower surface 12 of the holding member 10 via a bonding layer 30.

[0031] The base member 20 is provided with a coolant flow path 21 for flowing a coolant (e.g., a fluorine-based inert liquid, water, or the like). By flowing a coolant through the coolant flow path 21, the base member 20 is cooled, and the holding member 10 is cooled via the bonding layer 30. This allows the semiconductor wafer W held on the holding surface 11 to be cooled, and the electrostatic chuck 1 enables temperature control of the semiconductor wafer W. In this way, heat is transferred between the semiconductor wafer W and the base member 20 via the holding member 10 and the bonding layer 30.

[0032] 1 and 2, the bonding layer 30 is disposed between the lower surface 12 of the holding member 10 and the base member 20, and bonds the holding member 10 and the base member 20 in a heat-transferable manner. The bonding layer 30 is made of a resin adhesive such as a silicone resin, an acrylic resin, or an epoxy resin.

[0033] <Details of the holding member> Next, the holding member 10 of this embodiment will be described in detail.

[0034] When the holding member 10 holds the semiconductor wafer W, a space S is provided between the holding surface 11 and the semiconductor wafer W, which is filled with helium gas having high thermal conductivity, in order to control the temperature of the semiconductor wafer W. However, directly below the holding surface 11 of the holding member 10, there are complex structures such as a gas tunnel 16 and a chuck electrode 18, and there may be locations where excessive heat transfer is likely to occur. This makes it difficult to control the temperature of the semiconductor wafer W, and there is a risk of temperature singularities occurring in the semiconductor wafer W.

[0035] Therefore, in the holding member 10 of this embodiment, the thermal conductivity of the portion on the holding surface 11 side is reduced to prevent excessive heat transfer locally between the holding member 10 and the semiconductor wafer W, thereby achieving uniform heat transfer overall. This allows the temperature of the semiconductor wafer W to be appropriately controlled, and the occurrence of temperature singularities in the semiconductor wafer W can be suppressed.

[0036] Specifically, as shown in FIGS. 2 and 4, the holding member 10 includes a substrate portion 41 and an IAD film portion 42 (ie, an ion-assisted deposition film portion).

[0037] The substrate 41 is a disk-shaped member made of ceramic. Various ceramics can be used to form the substrate 41, but from the viewpoints of strength, wear resistance, plasma resistance, etc., it is preferable to use ceramics whose main component is alumina (aluminum oxide, Al2O3) or aluminum nitride (AlN). Note that the term "main component" as used here refers to the component with the highest content (for example, a component with a volume content of 90 vol% or more).

[0038] The IAD film 42 is provided on the side of the substrate 41 that holds the semiconductor wafer W, and is formed of, for example, an alumina ion-assisted deposition film. The IAD film 42 is provided with a surface layer 51, a holding surface 11, an annular protrusion 13, and a pin-shaped protrusion 14.

[0039] The surface layer 51 is a portion of the IAD film 42 provided on the substrate 41 side, and is formed so as to cover the upper surface of the substrate 41. The upper surface of the surface layer 51 (the surface on which the semiconductor wafer W is held) is provided with the holding surface 11, the annular protrusions 13, and the pin-shaped protrusions 14. In this way, at least a portion of the surface layer 51 is exposed to the surface (i.e., the surface of the holding member 10 on which the semiconductor wafer W is held).

[0040] In this embodiment, the IAD film portion 42 is formed from an ion-assisted deposition film formed at a substrate temperature of 150°C to 350°C, and the crystallinity of the material (e.g., an ion-assisted deposition film of alumina) constituting the surface layer portion 51, which is part of the IAD film portion 42, is lower than the crystallinity of the material (e.g., alumina) constituting the base material portion 41.

[0041] In this way, by making the crystallinity of the material constituting the surface layer 51 lower than that of the material constituting the base portion 41, phonons are scattered by atomic disorder, and the thermal conductivity of the surface layer 51 is made lower than that of the base portion 41. Therefore, even if the base portion 41 has portions where excessive heat transfer is likely to occur due to the presence of internal structures (e.g., the gas tunnel 16, the chuck electrode 18, etc.), the surface layer 51 with low thermal conductivity is provided between the semiconductor wafer W and the base portion 41, thereby suppressing excessive heat transfer in parts and enabling uniform heat transfer overall. Therefore, the occurrence of temperature singularities in the semiconductor wafer W can be suppressed.

[0042] Here, the applicant prepared an alumina substrate and a film (10 μm thick) formed by ion-assisted deposition of alumina on the alumina substrate, and analyzed each by X-ray diffraction (XRD). Two film-formed samples were prepared: one in which the temperature conditions for film formation by ion-assisted deposition were 300°C (hereinafter referred to as "film-formed under 300°C conditions") and one in which the temperature conditions for film formation were 150°C (hereinafter referred to as "film-formed under 150°C conditions").

[0043] As a result, the results shown in Figures 5 to 7 were obtained. In the diffraction patterns shown in Figures 5 to 7, multiple diffraction peaks attributed to α-Al2O3 constituting the alumina substrate were confirmed, and the diffraction pattern when the diffraction peaks attributed to α-Al2O3 were excluded is shown by the dotted line.

[0044] As a result, as shown by the dotted line in Figure 6, in comparison with the results for the alumina substrate (dotted line in Figure 5), the diffraction pattern of the film deposited at 300°C confirmed broad diffraction peaks that spread laterally and were low in height, which belong to γ-Al2O3 or δ-Al2O3, in regions RE1 and RE2 where the diffraction angle 2θ was 40° or more. Specifically, diffraction peaks with a half-width δ of 3° or more were confirmed in regions RE1 and RE2.

[0045] Furthermore, as shown by the dotted line in Figure 7, compared to the results for the alumina substrate (dotted line in Figure 5), the film deposited at 150°C is thought to have a lower crystallinity in the ion-assisted deposition film than the film deposited at 300°C, resulting in a completely amorphous state.In the diffraction pattern, a halo pattern (diffuse diffraction peak shape) due to amorphous nature was confirmed in the low-angle region RE3 (diffraction angle 2θ greater than or equal to 0° and less than 40°).

[0046] Therefore, in this embodiment, the surface layer portion 51 formed by the ion-assisted deposition film has physical properties equivalent to those of the ion-assisted deposition film in the film formed at 300° C. or 150° C. That is, the X-ray diffraction pattern of the surface layer portion 51 has at least one diffraction peak with a half-width δ of 3° or more at a diffraction angle 2θ of 40° or more, or has an amorphous halo pattern at a diffraction angle 2θ in the range of 0° or more and less than 40°.

[0047] Furthermore, since the surface layer 51 is formed of an ion-assisted vapor deposition film with high adhesiveness, the adhesiveness between the surface layer 51 and the base material 41 is improved.

[0048] In addition, in this embodiment, since the annular protrusions 13 and the pin-shaped protrusions 14 are also part of the IAD film portion 42, the materials constituting the annular protrusions 13 and the pin-shaped protrusions 14 also have a lower degree of crystallinity than the material constituting the base material portion 41.

[0049] In this way, the crystal grains in the annular protrusions 13 and the pin-shaped protrusions 14 can be reduced to make them uniformly amorphous. This makes it possible to suppress the occurrence of particle shedding due to friction between the annular protrusions 13 and the pin-shaped protrusions 14 and the semiconductor wafer W. This reduces the size of particles generated by use of the holding member 10. Furthermore, by reducing the crystallinity of the annular protrusions 13 and the pin-shaped protrusions 14, it is possible to suppress excessive heat transfer from the annular protrusions 13 and the pin-shaped protrusions 14 to the semiconductor wafer W, thereby improving the uniformity of the temperature distribution of the semiconductor wafer W.

[0050] Furthermore, it is preferable that the IAD film portion 42 is made of the same material as the base material portion 41. For example, it is preferable that the base material portion 41 is made of alumina (more specifically, the ceramic that forms the base material portion 41 is a ceramic whose main component is alumina), and the IAD film portion 42 is made of the same material as the base material portion 41, that is, alumina.

[0051] In this way, the surface layer 51, which is part of the IAD film 42, is preferably made of the same material as the base material 41. This allows the thermal expansion coefficient of the surface layer 51 to be equal to that of the base material 41. This makes it possible to prevent problems caused by the difference in thermal expansion coefficient (for example, problems such as the surface layer 51 peeling off from the base material 41 during thermal expansion).

[0052] In addition, a method for manufacturing such a holding member 10 can be considered in which an IAD film portion 42 is formed by ion-assisted deposition on the surface of the base material portion 41 that has been surface-polished, and then the upper surface of the IAD film portion 42 (the surface on which the semiconductor wafer W is held) is surface-polished and then scraped to form annular protrusions 13 and pin-shaped protrusions 14.

[0053] It should be noted that the above-described 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 within the scope of the gist of the present disclosure.

[0054] For example, the IAD film portion 42 (including the surface layer portion 51) may be made of a material different from that of the base material portion 41. [Explanation of symbols]

[0055] 1. Electrostatic chuck 10. Retaining member 11 Holding surface 13 Annular convex part 14 Pin-shaped protrusion 16 Gas Tunnel 18 Chuck electrode 20 Base member 30 Bonding layer 41 Base material part 42 IAD membrane section 51 Surface layer W Semiconductor wafer S space δ half-width

Claims

1. In a holding member for holding an object, A substrate portion; a surface layer portion provided on the side of the substrate portion that holds the object, and at least a portion of which is exposed to the surface; the material constituting the surface layer portion has a lower crystallinity than the material constituting the base portion; A holding member characterized by:

2. The holding member of claim 1, The X-ray diffraction pattern of the surface layer portion is having at least one diffraction peak having a diffraction angle 2θ of 40° or more and a half-value width of 3° or more; or a halo pattern derived from an amorphous material is present within the diffraction angle 2θ range of 0° or more and less than 40°; A holding member characterized by:

3. The holding member according to claim 1 or 2, a holding surface provided on a side of the surface portion that holds the object; a protrusion formed from the holding surface toward the side where the object is held, on which the object is placed, the material constituting the convex portions has a lower crystallinity than the material constituting the base portion; A holding member characterized by:

4. The holding member according to claim 1 or 2, the surface layer portion is made of the same material as the base material portion; A holding member characterized by:

5. The holding member according to claim 1 or 2, the surface layer portion is formed of an ion-assisted vapor deposition film; A holding member characterized by:

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