Holding member

Abstract

To provide a holding member that can ensure uniform temperature distribution of the object.SOLUTION: In one aspect of the present disclosure, a holding member 10 for holding a semiconductor wafer W includes a base portion 41, a holding surface 11 provided on the side of the base portion 41 where the semiconductor wafer W is held, and an annular protrusion 13 formed in a ring shape and protruding along the outer periphery of the holding surface 11, and the Young's modulus of the end face 13a of the annular protrusion 13 on which the semiconductor wafer W is placed is lower than the Young's modulus of 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 a substrate mounting table having a mounting surface on which a substrate is placed. The substrate is supported by a first support, a second support, and a third support provided on the mounting surface. A heat transfer gas is introduced into a space surrounded by the second support and formed between the mounting surface and the substrate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-152526 Summary of the Invention [Problem to be solved by the invention]

[0004] In the substrate mounting table of Patent Document 1, the second support part is formed of a highly rigid material (such as polyimide or quartz). Therefore, when an object is placed on and held on the end face of the second support part, the unevenness on the end face of the second support part is not crushed, and this unevenness creates a gap between the object and the end face, which may allow heat transfer gas to leak to the outside. This causes the pressure of the heat transfer gas in the space to become unstable, which may make it difficult to ensure a uniform temperature distribution of the object.

[0005] Therefore, the present disclosure has been made to solve the above-mentioned problems, and has an object to provide a holding member that can ensure uniformity of the temperature distribution of an object. [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, a holding surface provided on the side of the base portion where the object is held, and a peripheral convex portion formed in a ring shape and protruding along the outer periphery of the holding surface at the outer periphery of the holding surface, and the Young's modulus of the end face of the peripheral convex portion on which the object is placed is lower than the Young's modulus of the base portion.

[0007] According to this aspect, the end face of the outer peripheral convex portion has a low Young's modulus, and elastically deforms when an object is placed on and held on the end face of the outer peripheral convex portion, thereby eliminating any irregularities present on the end face of the outer peripheral convex portion. Therefore, when the object is held, it is possible to prevent a gap from forming between the object and the end face of the outer peripheral convex portion, and ensure airtightness of the space formed between the object and the holding surface inside the outer peripheral convex portion. Therefore, the pressure of the heat transfer gas filled in the space is stabilized, improving heat transfer between the object and the holding member, and ensuring uniformity of the temperature distribution of the object.

[0008] In the above aspect, it is preferable that the Young's modulus of the end face of the outer peripheral convex portion is 330 GPa or less.

[0009] According to this aspect, when an object is held, the end face of the outer peripheral convex portion can be elastically deformed more reliably.

[0010] In the above aspect, it is preferable that the surface roughness of the end face of the outer peripheral convex portion is arithmetic mean roughness Ra=0.2 μm or less.

[0011] According to this aspect, when the object is held, it is possible to more reliably prevent a gap from being generated between the object and the end face of the outer peripheral convex portion.

[0012] In the above aspect, it is preferable that the holding surface has an inner convex portion formed to protrude further inward than the outer peripheral convex portion, and that the Young's modulus of the end face of the inner convex portion on which the object is placed is lower than the Young's modulus of the base portion.

[0013] According to this aspect, the Young's modulus of the end face of the outer peripheral convex portion is reduced, and the Young's modulus of the end face of the inner convex portion is also reduced. Therefore, when an object is placed and held between the end faces of the outer peripheral convex portion and the inner convex portion, the end faces of the inner convex portion elastically deform along with the end faces of the outer peripheral convex portion. Therefore, even when the inner convex portion is provided on the holding surface, it is possible to prevent a gap from forming between the object and the end face of the outer peripheral convex portion when the object is held, thereby ensuring airtightness of the space formed between the object and the holding surface inside the outer peripheral convex portion. Therefore, the pressure of the heat transfer gas filled in the space is stabilized, improving heat transfer between the object and the holding member, thereby ensuring uniform temperature distribution of the object.

[0014] In the above aspect, it is preferable that the end face of the outer peripheral convex portion is made of the same material as the base portion.

[0015] According to this aspect, the thermal expansion coefficient of the end face of the outer circumferential convex portion is equal to the thermal expansion coefficient of the base portion, so that the influence of the difference in thermal expansion (for example, peeling of the outer circumferential convex portion) is less likely to occur.

[0016] In the above aspect, the end face of the outer peripheral convex portion is preferably formed of an ion-assisted vapor deposition film.

[0017] According to this aspect, the end face of the outer peripheral convex portion is formed of a dense ion-assisted vapor deposition film, which makes it possible to reduce the irregularities on the end face of the outer peripheral convex portion. [Effects of the Invention]

[0018] The holding member of the present disclosure can ensure uniformity of the temperature distribution of the object. [Brief explanation of the drawings]

[0019] [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 a test piece used in an experiment to measure Young's modulus. [Figure 6] 1 is a table showing the measurement results of Young's modulus of each test specimen. [Figure 7] 10 is an XZ cross-sectional view showing an enlarged view of an annular convex portion, a pin-shaped convex portion, and their surroundings in a holding member of a first modified example. FIG. [Figure 8] 10 is an XZ cross-sectional view showing an enlarged view of an annular convex portion, a pin-shaped convex portion, and their surroundings in a holding member of a second modified example. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0020] 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.

[0021] <Explanation of electrostatic chuck> First, the electrostatic chuck 1 will be described.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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).

[0026] The holding surface 11 of the holding member 10 has an uneven shape. Specifically, as shown in Figures 2 and 3, the holding surface 11 is provided with an annular protrusion 13 formed in a ring shape and protruding along the outer periphery of the holding surface 11 at its outer periphery (more specifically, near the outer edge). The annular protrusion 13 is also called a seal band, and is an example of the "outer periphery protrusion" of the present disclosure.

[0027] Furthermore, a plurality of columnar pin-shaped protrusions 14 are provided on the holding surface 11, protruding further inward than the annular protrusion 13. In this way, the holding surface 11 is provided with the annular protrusion 13 arranged so as to surround all of the plurality of pin-shaped protrusions 14. The pin-shaped protrusions 14 are an example of an "inner protrusion" in the present disclosure.

[0028] 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 and 3, the portion of the holding surface 11 inside the annular protrusion 13 where no pin-shaped protrusion 14 is provided is a recess 15.

[0029] 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 recesses 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 gas holes (not shown) opening in the holding surface 11 via a gas flow path (not shown) provided in the electrostatic chuck 1.

[0030] A chuck electrode (not shown) 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 to generate an electrostatic attractive force.

[0031] Further details of the holding member 10 will be described later.

[0032] 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.

[0033] The base member 20 is provided with a coolant flow path 21 for flowing a coolant (e.g., a fluorine-based inert liquid, water, etc.). 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 allows temperature control of the semiconductor wafer W.

[0034] 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.

[0035] <Details of the holding member> Next, the holding member 10 of this embodiment will be described in detail.

[0036] In the holding member 10, in order to ensure a uniform temperature distribution of the semiconductor wafer W when holding the semiconductor wafer W, a space S is provided between the semiconductor wafer W and the holding surface 11, into which helium gas is filled. Therefore, it is necessary to keep the annular protrusion 13 and the semiconductor wafer W in close contact with each other to prevent the helium gas from leaking to the outside.

[0037] However, if the annular protrusion 13 is made of a highly rigid material, when the semiconductor wafer W is placed on and held on the end face 13a of the annular protrusion 13, the unevenness present on the end face 13a of the annular protrusion 13 will not be crushed, and this unevenness may cause a gap between the semiconductor wafer W and the end face 13a, which may allow the helium gas in the space S to leak to the outside. This may result in an unstable pressure of the helium gas in the space S, making it difficult to ensure a uniform temperature distribution of the semiconductor wafer W.

[0038] Therefore, in the holding member 10 of this embodiment, the Young's modulus of the end face 13a of the annular protrusion 13 is made low so that when the semiconductor wafer W is placed on and held on the end face 13a, the end face 13a is elastically deformed to flatten the irregularities present on the end face 13a, thereby preventing a gap from occurring between the semiconductor wafer W and the end face 13a.

[0039] Specifically, as shown in FIGS. 3 and 4, the holding member 10 includes a substrate portion 41 and an IAD film portion 42 (ie, an ion-assisted deposition film portion).

[0040] 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).

[0041] 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 formed of an ion-assisted deposition film in this way, and its Young's modulus is lower than that of the substrate 41. The IAD film 42 is provided with a surface layer 51, a holding surface 11, an annular protrusion 13, and pin-shaped protrusions 14.

[0042] 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 a holding surface 11, an annular protrusion 13, and a pin-shaped protrusion 14.

[0043] In this embodiment, the annular protrusion 13 (including the end face 13a) and the pin-shaped protrusion 14 (including the end face 14a on which the semiconductor wafer W is placed) are formed as part of the IAD film portion 42 from an ion-assisted deposition film of alumina.

[0044] In this way, the annular protrusion 13 and the pin-shaped protrusion 14 are formed from an ion-assisted vapor deposition film of alumina, and the Young's modulus of the annular protrusion 13 (including the end face 13a) and the Young's modulus of the pin-shaped protrusion 14 (including the end face 14a) are lower than the Young's modulus of the base material portion 41.

[0045] As described above, the end face 13a of the annular protrusion 13 has a low Young's modulus, and therefore elastically deforms when the semiconductor wafer W is placed on and held on the end face 13a, thereby smoothing out any irregularities present on the end face 13a. Therefore, when the semiconductor wafer W is held by the holding member 10, it is possible to prevent a gap from being formed between the semiconductor wafer W and the end face 13a, and it is possible to ensure the airtightness of the space S formed between the semiconductor wafer W and the holding surface 11 inside the annular protrusion 13. Therefore, the pressure of the helium gas filled in the space S is stabilized, which improves the heat transfer between the semiconductor wafer W and the holding member 10, thereby ensuring a uniform temperature distribution of the semiconductor wafer W.

[0046] Furthermore, in this embodiment, the Young's modulus of the end faces 14a of the pin-shaped protrusions 14 is also low. Therefore, when the semiconductor wafer W is held by the holding member 10, the end faces 14a of the pin-shaped protrusions 14 elastically deform together with the end faces 13a of the annular protrusions 13. Therefore, when the semiconductor wafer W is held by the holding member 10, it is possible to more reliably prevent gaps from being formed between the semiconductor wafer W and the end faces 13a of the annular protrusions 13, thereby ensuring airtightness of the space S. Therefore, it is possible to more reliably stabilize the pressure of the helium gas filled in the space S, thereby improving heat transfer between the semiconductor wafer W and the holding member 10, thereby ensuring a uniform temperature distribution of the semiconductor wafer W.

[0047] Here, the applicant prepared three test pieces as shown in Fig. 5: an alumina-based test piece, a test piece in which an alumina thin film (i.e., an alumina ion-assisted deposition film) (thickness: 10 µm) was formed on the alumina base material by ion-assisted deposition, and a test piece in which an yttria thin film (i.e., an yttria (yttrium oxide, YO)) ion-assisted deposition film) (thickness: 17 µm) was formed on the alumina base material by ion-assisted deposition. The applicant then conducted an experiment to measure the Young's modulus of each test piece at each measurement point P (see Fig. 5) by nanoindentation.

[0048] As a result, the measurement results shown in Figure 6 were obtained. As shown in Figure 6, the minimum Young's modulus of the alumina substrate was approximately 360 GPa, while the maximum Young's modulus of the alumina thin film was approximately 330 GPa, meaning that the alumina thin film had a lower Young's modulus than the alumina substrate. In addition, the maximum Young's modulus of the yttria thin film was approximately 205 GPa, meaning that the yttria thin film had a lower Young's modulus than the alumina substrate and alumina thin film. The minimum Young's modulus of the yttria thin film was approximately 190 GPa.

[0049] Therefore, in this embodiment, the Young's modulus of the annular protrusion 13 (including the end face 13a) and the pin-shaped protrusion 14 (including the end face 14a) formed by the ion-assisted deposition film of alumina is set to 330 GPa or less. More preferably, the Young's modulus of the annular protrusion 13 and the pin-shaped protrusion 14 is set to 190 GPa or more and 330 GPa or less.

[0050] This allows the end face 13a of the annular protrusion 13 and the end face 14a of the pin-shaped protrusion 14 to be elastically deformed more reliably when the semiconductor wafer W is held by the holding member 10.

[0051] The surface roughness of the end face 13a of the annular projection 13 is set to an arithmetic mean roughness Ra of 0.2 μm or less, and more preferably, the surface roughness of the end face 13a is set to an arithmetic mean roughness Ra of 0.1 μm or less.

[0052] This makes it possible to more reliably prevent a gap from being generated between the semiconductor wafer W and the end face 13a of the annular protrusion 13 when the semiconductor wafer W is held by the holding member 10.

[0053] In this embodiment, even if the surface roughness of the end face 13a of the annular protrusion 13 or the end face 14a of the pin-shaped protrusion 14 becomes somewhat large (for example, even if it becomes larger than the arithmetic mean roughness Ra = 0.2 μm), the Young's modulus of the end face 13a of the annular protrusion 13 or the end face 14a of the pin-shaped protrusion 14 is low, so that when the semiconductor wafer W is placed and held on the end face 13a and the end face 14a, the unevenness of the end face 13a is smoothed by elastic deformation, thereby preventing a gap from occurring between the semiconductor wafer W and the end face 13a.

[0054] Furthermore, in this embodiment, the annular protrusion 13 (including the end surface 13a) is formed of a dense ion-assisted vapor deposition film, so that the irregularities present on the end surface 13a of the annular protrusion 13 can be reduced.

[0055] Furthermore, the IAD film portion 42 may be made of the same material as the substrate portion 41, or may be made of a different material than the substrate portion 41. For example, if the substrate portion 41 is made of alumina, the IAD film portion 42 may be made of alumina, which is the same material as the substrate portion 41, or the IAD film portion 42 may be made of yttria, which is a different material than the substrate portion 41.

[0056] Furthermore, if the IAD film portion 42 is made of the same material as the base material portion 41, the thermal expansion coefficient of the annular protrusions 13 and pin-shaped protrusions 14 provided on the IAD film portion 42 will be equal to the thermal expansion coefficient of the base material portion 41, thereby reducing the effects of differences in thermal expansion (for example, peeling of the annular protrusions 13 and pin-shaped protrusions 14).

[0057] 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 substrate 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.

[0058] 7, the holding member 10 of the first modified example may be configured such that the IAD film portion 42 does not include the surface layer portion 51, and only includes the annular convex portion 13 and the pin-shaped convex portions 14. In the first modified example, the holding surface 11 is provided on the upper surface of the base portion 41 (the surface on the side where the semiconductor wafer W is held).

[0059] 8, in a second modified holding member 10, the IAD film portion 42 may not be provided with a surface layer portion 51, and the IAD film portion 42 may be formed only on the upper ends of the annular protrusions 13 and the pin-shaped protrusions 14. For this second modified holding member 10, for example, it is conceivable to form the annular protrusions 13 and the pin-shaped protrusions 14 in advance on the base material portion 41, and then form the IAD film portion 42 only on the annular protrusions 13 and the pin-shaped protrusions 14 by ion-assisted deposition.

[0060] 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.

[0061] For example, in a method for manufacturing the holding member 10, the annular protrusions 13 and the pin-shaped protrusions 14 may be formed in advance on the base material portion 41, and then the IAD film portion 42 may be formed on the entire holding surface 11 by ion-assisted deposition. [Explanation of symbols]

[0062] 1. Electrostatic chuck 10. Retaining member 11 Holding surface 13 Annular convex part 13a End face 14 Pin-shaped protrusion 14a End face 20 Base member 30 Bonding layer 41 Base material part 42 IAD membrane section W Semiconductor wafer S space

Claims

1. In a holding member for holding an object, A substrate portion; a holding surface provided on a side of the base member where the object is held; an outer peripheral protrusion formed in an annular shape along the outer periphery of the holding surface and protruding from the outer periphery of the holding surface; the Young's modulus of the end surface of the outer peripheral convex portion on which the object is placed is lower than the Young's modulus of the base portion; A holding member characterized by:

2. The holding member of claim 1, the Young's modulus of the end surface of the outer peripheral convex portion is 330 GPa or less; A holding member characterized by:

3. The holding member according to claim 1 or 2, the surface roughness of the end face of the outer peripheral convex portion is an arithmetic mean roughness Ra of 0.2 μm or less; A holding member characterized by:

4. The holding member according to claim 1 or 2, an inner convex portion formed to protrude on the holding surface at a position inside the outer peripheral convex portion, the Young's modulus of the end surface of the inner convex portion on which the object is placed is lower than the Young's modulus of the base portion; A holding member characterized by:

5. The holding member according to claim 1 or 2, the end surface of the outer peripheral convex portion is made of the same material as the base portion; A holding member characterized by:

6. The holding member according to claim 1 or 2, the end face of the outer peripheral convex portion is formed of an ion-assisted vapor deposition film; A holding member characterized by:

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