Electrostatic chuck member and electrostatic chuck device

Abstract

Provided is an electrostatic chuck member which comprises a substrate and an electrostatic attraction electrode, wherein: the substrate has a first attraction part and a second attraction part; the electrostatic attraction electrode includes a first electrode provided to the first attraction part and a second electrode provided to the second attraction part; a first lateral circumferential surface of the substrate has a first curved surface that is a convex curved surface provided in the circumferential direction, and a second curved surface provided in the circumferential direction at a different height position from that of the first curved surface; and a second lateral circumferential surface of a second placement surface has a third curved surface that is a convex curved surface provided in the circumferential direction and a fourth curved surface provided in the circumferential direction at a different height position from that of the third curved surface. Furthermore, said electrostatic chuck member satisfies the following formula (1).　Formula (1): W1>t1+t2 (where W1 is the width of the second attraction part, t1 is the height from the second placement surface to a first placement surface, and t2 is the height from the lower surface of the substrate to the second placement surface)

Description

Electrostatic chuck member and electrostatic chuck device

[0001] The present invention relates to an electrostatic chuck member and an electrostatic chuck device. This application claims priority based on Japanese Patent Application No. 2025-053468, filed in Japan on March 27, 2025, the contents of which are incorporated herein by reference.

[0002] Conventionally, in semiconductor manufacturing processes for producing semiconductor devices such as ICs, LSIs, and VLSIs, plate-shaped samples such as silicon wafers are fixed to an electrostatic chuck member equipped with an electrostatic chuck function by electrostatic adsorption and then subjected to predetermined processing. In such processes, for example, after fixing the silicon wafer with an electrostatic chuck device, the silicon wafer is subjected to etching or film deposition processing using plasma.

[0003] When an electrostatic chuck is used in the manufacturing process described above, particulate foreign matter (hereinafter referred to as "foreign particles"), such as wafer residue, may be generated on the electrostatic chuck components. Such foreign particles become charged within the semiconductor manufacturing equipment and adhere to the surface of the electrostatic chuck. In an electrostatic chuck with charged foreign particles attached, the plasma stability during the manufacturing process may be impaired, potentially reducing productivity. Furthermore, foreign particles may cause abnormal discharge during the plasma process, impairing plasma stability and potentially leading to a decrease in device yield or dielectric breakdown of the electrostatic chuck.

[0004] To address the above-mentioned challenges, in the semiconductor manufacturing process, electrostatic chuck devices contaminated with foreign particles are subjected to plasma cleaning to remove the foreign particles (see, for example, Patent Document 1).

[0005] Special Publication No. 2013-512564

[0006] In recent years, proposals have been made to enlarge the electrostatic adsorption electrodes of electrostatic chuck members in order to improve the yield of semiconductor chips obtained from silicon wafers. With electrostatic chuck members that have enlarged electrostatic adsorption electrodes, the difference in adsorption force between the center and the periphery of the wafer mounting surface is reduced, making it possible to perform the same processing (etching) on ​​the outer periphery of the silicon wafer as on the central part. As a result, semiconductor chips can be suitably manufactured even on the outer periphery of the silicon wafer, improving the yield.

[0007] On the other hand, as the electrostatic adsorption electrode is enlarged, the distance between the side surface of the electrostatic chuck member and the electrostatic adsorption electrode decreases, and the electric field strength on the side surface of the electrostatic chuck member increases. Therefore, in an electrostatic chuck member with an enlarged electrostatic adsorption electrode, charged foreign particles are more easily electrostatically adsorbed to the side surface compared to a conventional electrostatic chuck.

[0008] The electrostatic chuck member described in Patent Document 1 has a slanted section around its periphery to enhance the effect of plasma cleaning. However, while this configuration can effectively clean the wafer before the manufacturing process, it does not prevent charged foreign particles from adhering to the sides of the electrostatic chuck member during the manufacturing process. Therefore, there was a problem in that it could not adequately suppress problems such as reduced yield (decreased productivity) of elements due to abnormal discharges that occur during the wafer manufacturing process, or dielectric breakdown of the electrostatic chuck. For this reason, there was a need for an electrostatic chuck member that could reduce the influence of charged foreign particles adhering to the sides of the electrostatic chuck member even during the wafer manufacturing process, and suppress the occurrence of abnormal discharges.

[0009] The present invention has been made in view of these circumstances, and aims to provide an electrostatic chuck member that can reduce problems caused by the adhesion of charged foreign particles to the side surface, particularly abnormal discharges that occur during wafer processing. It also aims to provide an electrostatic chuck device having such an electrostatic chuck member.

[0010] To solve the above problems, one aspect of the present invention includes the following aspects.

[0011] [1] An electrostatic chuck member comprising a substrate made of a dielectric material and an electrostatic adsorption electrode provided inside the substrate, wherein the substrate has a first adsorption portion whose upper surface is a first mounting surface on which a plate-shaped sample is placed, and a second adsorption portion formed in a closed annular shape below the first adsorption portion and outside the first adsorption portion in a plan view, with the upper surface being a second mounting surface on which a focus ring is placed, and the electrostatic adsorption electrode includes a first electrode provided in the first adsorption portion and a second electrode provided in the second adsorption portion, and the substrate The electrostatic chuck member is an electrostatic chuck member that satisfies the following formula (1): W1 > t1 + t2 ... (1) (W1: width of the second suction part, t1: height from the second suction surface to the first suction surface, t2: height from the bottom surface of the base to the second suction surface)

[0012] [2] The electrostatic chuck member according to [1], wherein the radius of curvature of the first curved surface and the radius of curvature of the second curved surface are both greater than the thickness of the first electrode, and the radius of curvature of the third curved surface and the radius of curvature of the fourth curved surface are both greater than the thickness of the second electrode.

[0013] [3] The electrostatic chuck member according to [1] or [2], wherein the first side surface and the second mounting surface are connected by a concave curved surface.

[0014] [4] The electrostatic chuck member according to [3], wherein the radius of curvature of the concave surface is greater than the radius of curvature of any of the first, second, third, and fourth surfaces.

[0015] [5] An electrostatic chuck member according to any one of items [1] to [4] that satisfies the following formula (2): L1 < L2 ... (2) (L1: length of the first imaginary line connecting the upper end of the first curved surface and the lower end of the second curved surface L2: length of the second imaginary line connecting the upper end of the third curved surface and the lower end of the fourth curved surface)

[0016] [6] An electrostatic chuck member according to any one of items [1] to [5] that satisfies the following formula (3): θ2 < θ1 ... (3) (θ1: An elevation angle of the midpoint of a first imaginary line connecting the upper end of the first curved surface and the lower end of the second curved surface, with reference to the end of the first side surface of the first electrode θ2: An elevation angle of the midpoint of a second imaginary line connecting the upper end of the third curved surface and the lower end of the fourth curved surface, with reference to the end of the second side surface of the second electrode)

[0017] An electrostatic chuck device comprising an electrostatic chuck member as described in any one of items [7], [1] to [6], and a base member that cools the electrostatic chuck member and adjusts the temperature of the electrostatic chuck member.

[0018] According to the present invention, it is possible to provide an electrostatic chuck member that can reduce problems caused by the adhesion of charged foreign particles to the side surface. Furthermore, it is possible to provide an electrostatic chuck device having such an electrostatic chuck member.

[0019] Figure 1 is a schematic perspective view of the electrostatic chuck member 10 of this embodiment. Figure 2 is a cross-sectional view showing the electrostatic chuck member 10 of this embodiment. Figure 3 is a cross-sectional view of the electrostatic chuck member 10 of this embodiment. Figure 4 is an enlarged cross-sectional view of the peripheral edges of the first adsorption portion 21 and the second adsorption portion 22. Figure 5 is an enlarged cross-sectional view of the peripheral edges of the first adsorption portion 21 and the second adsorption portion 22. Figure 6 is an enlarged cross-sectional view of the peripheral edges of the first adsorption portion 21 and the second adsorption portion 22. Figure 7 is a partial cross-sectional view showing an electrostatic chuck member 10B according to a modified example. Figure 8 is a cross-sectional view showing the electrostatic chuck device 1A of this embodiment. Figure 9 is an explanatory diagram of a semiconductor manufacturing apparatus 1000 having the electrostatic chuck device described above.

[0020] As an electrostatic chuck device (electrostatic chuck member), a configuration is known that includes a first suction portion that sucks and holds a wafer, which is an object to be processed, on its upper surface, and a second suction portion that sucks and holds a focus ring on its upper surface.

[0021] A "focus ring" is an annular component in plan view that surrounds the outer circumference of a wafer in an electrostatic chuck device. The focus ring functions to maintain a uniform electrical environment between the peripheral portion and the central portion of the wafer during plasma processing. The focus ring is formed of a material similar to that of the wafer, and partially overlaps the wafer in plan view, thereby having a function of extending the electrical environment in the radial direction of the wafer.

[0022] Due to the above function, the upper surface of the second suction portion that holds the focus ring is formed lower than the upper surface of the first suction portion that sucks the wafer. As a result, the side surfaces of the electrostatic chuck member having the above configuration include two portions: the side surface of the first suction portion (which may be referred to as a "first side peripheral surface" in this specification) and the side surface of the second suction portion (which may be referred to as a "second side peripheral surface" in this specification).

[0023] The inventors studied reducing the abnormal discharge in the electrostatic chuck member having the above configuration, and arrived at the idea that reducing charged foreign particles adhering to the side surface of the second suction portion is effective. For an electrostatic chuck device used in a plasma process, plasma cleaning is performed after each process of processing a wafer. The generation center of this plasma is located above the first suction portion. Therefore, the effect of plasma cleaning is lower on the second side peripheral surface than on the first side peripheral surface, and it is considered that charged foreign particles adhering to the second side peripheral surface are more difficult to remove than charged foreign particles adhering to the first side peripheral surface.

[0024] After intensive studies based on the above findings, the inventors arrived at the idea that the problem can be solved by forming an electrostatic chuck member with a shape and configuration capable of reducing charged foreign particles adhering to the second side peripheral surface, and thus completed the invention.

[0025] Hereinafter, the electrostatic chuck member according to an embodiment of the present invention will be described with reference to FIGS. 1 to 7. In all of the following drawings, the dimensions and proportions of each constituent element are appropriately changed to make the drawings easier to read.

[0026] <Electrostatic Chuck Member> FIG. 1 is a schematic perspective view of the electrostatic chuck member 10 of the present embodiment. FIG. 2 is a cross-sectional view showing the electrostatic chuck member 10 of the present embodiment, which is a cross-sectional view taken along line segment II-II in FIG. 1 as viewed in the direction of the arrows. FIG. 2 shows a state where a focus ring FR is placed on the electrostatic chuck member 10.

[0027] As shown in FIGS. 1 and 2, the electrostatic chuck member 10 includes a base body made of a dielectric material, and an electrostatic chucking electrode provided inside the base body.

[0028] The cross-sectional view shown in FIG. 2 is a cross-section obtained by cutting the electrostatic chuck member along an imaginary plane including the center of the smallest circle circumscribing the electrostatic chuck member in plan view. In other words, FIG. 2 is a cross-sectional view taken along a cross-section that passes through the center C of the base body (first mounting surface 21a) and includes the normal line N of the base body (first mounting surface 21a). When the electrostatic chuck member 10 is substantially circular in plan view, the center of the aforementioned circle substantially coincides with the center of the shape of the electrostatic chuck member in plan view.

[0029] In the present specification, "plan view" refers to a field of view viewed from the y-direction, which is the thickness direction of the electrostatic chuck member. In addition, "cross-sectional view" refers to a field of view in a direction orthogonal to the cross-section when cutting along an imaginary plane that includes the center of the smallest circle circumscribing the electrostatic chuck member in plan view and perpendicular to the mounting surface.

[0030] (Base Body) The base body 11 has a first suction portion 21 and a second suction portion 22. The first suction portion 21 and the second suction portion 22 are formed concentrically with the center C being concentric in plan view.

[0031] The first suction portion 21 is formed in a columnar (or disc-shaped) shape, and has a first mounting surface 21a that is an upper surface, and a first side peripheral surface 21b continuous with the first mounting surface 21a.

[0032] In the electrostatic chuck member 10 of this embodiment, the first mounting surface 21a is provided with a plurality of protrusions 211 that project upward. In addition, the peripheral edge of the upper surface of the first suction part 21 is provided with a closed annular protrusion 212 along the edge of the upper surface of the first suction part 21.

[0033] The first adsorption section 21 supports a plate-shaped sample (not shown) with the tips (upper surfaces) of the multiple protrusions 211 and the upper surface of the annular protrusion 212. In other words, in the first adsorption section 21, the virtual plane connecting the upper surface of the annular protrusion 212 and the upper surfaces of the multiple protrusions 211 is the first mounting surface 21a on which the plate-shaped sample is placed. Furthermore, if the virtual plane thus set is concave or convex, the mean square plane of the virtual plane is defined as the first mounting surface 21a.

[0034] The plate-shaped sample placed on the first mounting surface 21a is supported by contact with the upper surfaces of the convex portions 211 and the annular convex portions 212 that constitute the first mounting surface 21a. At this time, the space surrounded by the lower surface of the plate-shaped sample, the multiple convex portions 211 and the annular convex portions 212 functions as a flow channel 21x for the cooling gas to flow.

[0035] The second suction portion 22 is formed below the first suction portion 21 and, in a plan view, is formed in a closed annular shape on the outside of the first suction portion 21. The second suction portion 22 is formed in a concentric shape with a larger radius than the first suction portion 21 and is formed integrally with the first suction portion 21.

[0036] The upper surface of the second suction part 22 is the second mounting surface 22a on which the focus ring FR is placed. In a plan view, the second mounting surface 22a is exposed, surrounding the periphery of the first suction part 21.

[0037] An annular groove 22x is formed on the upper surface of the second adsorption portion 22 in plan view. When the focus ring FR is placed on the second mounting surface 22a, the space surrounded by the lower surface of the focus ring FR and the groove 22x functions as a flow path for the cooling gas.

[0038] Furthermore, the second suction portion 22 has a second circumferential surface 22b that is continuous with the second mounting surface 22a.

[0039] (Electrostatic adsorption electrode) The electrostatic adsorption electrode comprises a first electrode 13 provided on a first adsorption portion 21 and a second electrode 15 provided on a second adsorption portion 22. The first electrode 13 is an electrode that generates an electrostatic adsorption force on a first placement surface 21a. The second electrode 15 is an electrode that generates an electrostatic adsorption force on a second placement surface 22a.

[0040] In FIG. 2, the base body 11 is shown as one member spanning the first adsorption portion 21 and the second adsorption portion 22, but the base body 11 is not limited thereto. The base body 11 may be a laminate obtained by laminating a plurality of ceramic plates and bonding the ceramic plates with an adhesive or joining them with an inorganic binder.

[0041] (Base body) The base body 11 is made of a dielectric material. The dielectric material may be composed of an insulating material, or may be composed of a composite of an insulating material and a conductive material.

[0042] The insulating material contained in the base body 11 is not particularly limited, and examples thereof include aluminum oxide (Al ２ O ３ ), aluminum nitride (AlN), yttrium oxide (Y ２ O ３ ), yttrium aluminum garnet (YAG), and the like. Among these, Al ２ O ３ and AlN are preferable.

[0043] The conductive material contained in the base body 11 is not particularly limited, and examples thereof include silicon carbide (SiC), titanium oxide (TiO ２ ), titanium nitride (TiN), titanium carbide (TiC), carbon materials, rare earth oxides, rare earth fluorides, and the like. Examples of the carbon material include carbon nanotubes (CNT) and carbon nanofibers. Among these, SiC is preferable.

[0044] The material of the base body 11 is not particularly limited as long as it has a volume resistivity of 10 １３ Ω·cm or more and 10 １７ Ω·cm or less, has mechanical strength, and has durability against corrosive gas and plasma thereof. As such a material, for example, Al ２ O ３Sintered body, AlN sintered body, Al ２ O ３ - Examples include SiC composite sintered bodies. From the viewpoint of dielectric properties at high temperatures, high corrosion resistance, plasma resistance, and heat resistance, the material of the substrate 11 is Al ２ O ３ - SiC composite sintered bodies are preferred.

[0045] The average primary particle diameter of the insulating material constituting the substrate 11 is preferably 0.5 μm or more and 3.0 μm or less, more preferably 0.7 μm or more and 2.0 μm or less, and even more preferably 1.0 μm or more and 2.0 μm or less.

[0046] If the average primary particle size of the insulating material constituting the substrate 11 is 0.5 μm or more and 3.0 μm or less, a dense substrate 11 with high dielectric strength and durability can be obtained.

[0047] The method for measuring the average primary particle diameter of the insulating material constituting the substrate 11 is as follows: The cross-section in the thickness direction of the substrate 11 is observed at 10,000x magnification using a field emission scanning electron microscope (FE-SEM, JSM-7800F-Prime, manufactured by JEOL Ltd.), and the average particle diameter of 200 insulating materials is taken as the average primary particle diameter using the intercept method.

[0048] (Focus Ring) The focus ring FR is an annular member in plan view that is supported on the second mounting surface 22a. The focus ring FR has a support portion FR1 that has an upper surface at the same height as the first mounting surface 21a when supported on the second mounting surface 22a, and an annular protrusion portion FR2 that protrudes upward from the upper surface of the support portion FR1 on the outer circumference of the focus ring FR.

[0049] The focus ring FR is formed from a material having electrical conductivity equivalent to that of the plate-shaped sample placed on the first mounting surface 21a, for example. Specifically, silicon, silicon carbide, quartz, aluminum oxide, etc., can be used as the constituent material of the focus ring FR.

[0050] When plasma-treating a plate-shaped sample using an electrostatic chuck device having an electrostatic chuck member 10, the plate-shaped sample is placed across the upper surface of the support part FR1 from the first mounting surface 21a. This allows the electrical environment at the periphery of the plate-shaped sample to be expanded radially while generally matching that of the plate-shaped sample, thereby reducing differences and biases in plasma treatment between the central and peripheral parts of the plate-shaped sample.

[0051] (Electrodes for electrostatic adsorption) The first electrode 13 is used to generate an electric charge and fix a plate-shaped sample by electrostatic adsorption force. The second electrode 15 is used to generate an electric charge and fix the focus ring FR by electrostatic adsorption force. In the following description, the first electrode 13 and the second electrode 15 will be collectively referred to as "electrodes for electrostatic adsorption".

[0052] Electrostatic adsorption electrodes are thin electrodes that have a greater extent in the direction perpendicular to the thickness direction than in the thickness direction. Such electrodes are formed by applying an electrode layer forming paste and sintering it. The thickness of the resulting electrode can be controlled by adjusting the thickness of the electrode layer forming paste, after determining the correspondence between the thickness of the electrode layer forming paste and the resulting electrode thickness through preliminary experiments.

[0053] Electrostatic adsorption electrodes are composed of a sintered body of conductive material particles, or a composite (sintered body) of insulating ceramic particles and conductive material particles.

[0054] When an electrostatic adsorption electrode is composed of insulating ceramics and a conductive material, the volume resistivity of this mixture is 10 －６ Ω・cm or more 10 －２ It is preferable that the value is approximately Ω·cm or less.

[0055] When the electrostatic adsorption electrode is composed of a composite of insulating ceramics and a conductive material, the content of the conductive material in the electrostatic adsorption electrode is preferably 15% by mass or more and 100% by mass or less, and more preferably 20% by mass or more and 100% by mass or less. If the content of the conductive material is above the lower limit, the substrate 11 can exhibit sufficient dielectric properties.

[0056] The conductive material included in the electrostatic adsorption electrode may be a conductive ceramic, or a conductive material such as a metal or carbon material. The conductive material included in the electrostatic adsorption electrode may be SiC, TiO ２ TiN, TiC, tungsten (W), tungsten carbide (WC), molybdenum (Mo), molybdenum carbide (Mo ２ C), tantalum (Ta), tantalum carbide (TaC, Ta ４ C ５ Preferably, at least one selected from the group consisting of carbon material and conductive composite sintered body.

[0057] Examples of carbon materials include carbon black, carbon nanotubes, and carbon nanofibers.

[0058] Examples of conductive composite sintered bodies include Al ２ O ３ -Ta ４ C ５ Al ２ O ３ -W, Al ２ O ３ Examples include SiC, AlN-W, and AlN-Ta.

[0059] The conductivity of the electrode can be ensured by ensuring that the conductive material included in the electrostatic adsorption electrode is at least one selected from the group consisting of the aforementioned substances.

[0060] The insulating ceramics included in the electrostatic adsorption electrode are not particularly limited, but for example, Al ２ O ３ AlN, silicon nitride (Si ３ N ４ ), Y ２ O ３ YAG, samarium-aluminum oxide (SmAlO ３ ), magnesium oxide (MgO) and silicon oxide (SiO ２ At least one selected from the group consisting of ) is preferred.

[0061] By making the electrostatic adsorption electrode from a conductive material and an insulating material, the bonding strength between the substrate 11 and the electrostatic adsorption electrode is improved. Furthermore, by making the electrostatic adsorption electrode from a conductive material and an insulating material, the mechanical strength of the electrode is increased.

[0062] The insulating material contained in the electrostatic adsorption electrode is Al ２ O ３ This ensures that dielectric properties, high corrosion resistance, plasma resistance, and heat resistance are maintained at high temperatures.

[0063] The ratio (mixing ratio) of conductive material to insulating material in the electrostatic adsorption electrode is not particularly limited and is adjusted as appropriate depending on the application of the electrostatic chuck member 10.

[0064] Although only one second electrode 15 is shown in Figure 2, this is not the only example. The electrostatic adsorption electrode of the second adsorption unit 22 may be bipolar.

[0065] (Shape of the electrostatic chuck member) Figure 3 is a cross-sectional view of the electrostatic chuck member 10, and is a view of the same field of view as Figure 2. The electrostatic chuck member 10 controls the configuration of each part as follows in order to suppress the adhesion of charged foreign particles to the second side circumferential surface 22b.

[0066] First, as shown in Figures 2 and 3, the first circumferential surface 21b of the base 11 of the electrostatic chuck member 10, which is continuous with the first mounting surface 21a, has a first curved surface CS1 provided in the circumferential direction at the periphery of the first mounting surface 21a, and a second curved surface CS2 provided in the circumferential direction at a different height position from the first curved surface CS1. Both the first curved surface CS1 and the second curved surface CS2 of the electrostatic chuck member 10 are convex curved surfaces.

[0067] Furthermore, on the first side circumferential surface 21b of the electrostatic chuck member 10, the area between the first curved surface CS1 and the second curved surface CS2 is a first inclined surface 21c that is exposed to the field of view from the direction of the first mounting surface 21a. That is, the first side circumferential surface 21b includes the first curved surface CS1, the first inclined surface 21c, and the second curved surface CS2 in this order, starting from the first mounting surface 21a side.

[0068] In this specification, "convex surface" refers to a side surface that is convex in the +y direction when viewed in cross-section. On the other hand, "inclined surface" refers to a side surface that has a constant inclination when viewed in cross-section.

[0069] The first inclined surface 21c is a surface in which the corners along the virtual surfaces S1 and S2 are linearly chamfered. Furthermore, at both ends of the first inclined surface 21c in the field of view of Figures 2 and 3, the two new corners created by the chamfering are processed into a first curved surface CS1 and a second curved surface CS2, which are outwardly convex curved surfaces (convex curved surfaces).

[0070] Similarly, the second circumferential surface 22b of the base 11, which is continuous with the second mounting surface 22a, has a third curved surface CS3 provided circumferentially at the periphery of the second mounting surface 22a, and a fourth curved surface CS4 provided circumferentially at a different height position from the third curved surface CS3. Both the third curved surface CS3 and the fourth curved surface CS4 are convex curved surfaces.

[0071] Furthermore, the area between the third curved surface CS3 and the fourth curved surface CS4 is the second inclined surface 22c, which is exposed in the field of view from the direction of the second mounting surface 22a. That is, the second side circumferential surface 22b includes the third curved surface CS3, the second inclined surface 22c, and the fourth curved surface CS4 in this order, starting from the second mounting surface 22a side.

[0072] The second inclined surface 22c is a surface in which the corners along the virtual surfaces S3 and S4 are linearly chamfered. Furthermore, at both ends of the second inclined surface 22c in the field of view of Figures 2 and 3, the two new corners created by the chamfering are processed into a third curved surface CS3 and a fourth curved surface CS4, which are convex curved surfaces that protrude outward.

[0073] Furthermore, the electrostatic chuck member 10 satisfies the following equation (1): W1 > t1 + t2 ... (1) (W1: width of the second suction part 22 t1: height from the second mounting surface 22a to the first mounting surface 21a t2: height from the lower surface 11a of the base body 11 to the second mounting surface 22a)

[0074] Conventional electrostatic chuck members have corners at the top of their side surfaces. Furthermore, if the top of the side surface is chamfered in a straight line, two corners are formed on the side surface. On the other hand, the electrostatic field required to adsorb a plate-shaped sample tends to concentrate at the aforementioned corners of the side surface, and charged foreign particles attracted to this electrostatic field tend to adhere firmly and in large numbers to the narrow area around the corners of the side surface.

[0075] In contrast, if the corners of the electrostatic chuck member 10 are curved, forming a first curved surface CS1, a second curved surface CS2, a third curved surface CS3, and a fourth curved surface CS4, the electrostatic field described above is dispersed across each curved surface and is less likely to concentrate in a specific location. As a result, the adhesion sites of charged foreign particles are dispersed, and the number of charged foreign particles per unit surface area decreases, making it easier to suppress abnormal discharge.

[0076] Furthermore, when the corners of the first suction portion 21 are curved, the areas of the formed first curved surface CS1 and second curved surface CS2 are smaller than the area of ​​the surface that extends from the end of the first mounting surface 21a, through virtual surfaces S1 and S2, to the lower end of the second curved surface CS2, that is, the area of ​​the surface that exists when the corners are not curved. Similarly, when the corners of the first suction portion 21 are curved, the areas of the formed third curved surface CS3 and fourth curved surface CS4 are smaller than the area of ​​the surface that extends from the end of the second mounting surface 22a, through virtual surfaces S3 and S4, to the lower end of the second curved surface CS2, that is, the area of ​​the surface that exists when the corners are not curved.

[0077] As described above, charged foreign particles tend to adhere to the corners of the electrostatic chuck member. By curving the corners, the surface area of ​​the parts where charged foreign particles can adhere can be reduced, making it a suitable configuration for suppressing abnormal discharge.

[0078] Furthermore, if an abnormal discharge occurs on the second circumferential surface 22b, a relatively wide width W1 of the second adsorption portion 22 can reduce the impact on the plate-shaped member on the first mounting surface 21a.

[0079] The energy of the discharge is thought to be highest at the point where the abnormal discharge occurs and diffuses isotropically. As you move away from the point where the discharge occurred, the energy will attenuate inversely proportional to the cube of the distance between you and the point of discharge. An electrostatic chuck member that satisfies the above equation (1) has a sufficiently wide width W1 of the second adsorption part 22, which can reduce the impact of abnormal discharge.

[0080] It is preferable that W1 > (t1 + t2) × 2, and more preferably that W1 > (t1 + t2) × 4.

[0081] Furthermore, the electrostatic chuck member 10 is preferably configured as follows. Figures 4 to 6 are enlarged cross-sectional views of the peripheral edges of the first suction portion 21 and the second suction portion 22. Figure (a) shows the peripheral edge of the first suction portion 21, and Figure (b) shows the peripheral edge of the second suction portion 22.

[0082] (Radius of curvature of curved surface) As shown in Figure 4, it is preferable that the radius of curvature r1 of the first curved surface CS1 and the radius of curvature r2 of the second curved surface CS2 are both greater than the thickness d1 of the first electrode 13, and the radius of curvature r3 of the third curved surface CS3 and the radius of curvature r4 of the fourth curved surface CS4 are both greater than the thickness d2 of the second electrode 15.

[0083] In the first adsorption section 21, by making the radii of curvature of the first curved surface CS1 and the second curved surface CS2 larger than the thickness d1 of the first electrode 13, the concentration of the electric field on the first curved surface CS1 and the second curved surface CS2 during plasma processing can be suppressed. This makes it possible to suppress the concentration of charged foreign particles adhering to specific parts (for example, corners).

[0084] Similarly, in the second adsorption section 22, by making the radii of curvature of the third curved surface CS3 and the fourth curved surface CS4 larger than the thickness d2 of the second electrode 15, the concentration of the electric field on the third curved surface CS3 and the fourth curved surface CS4 during plasma processing can be suppressed. This makes it possible to suppress the concentration of charged foreign particles adhering to specific parts (for example, corners).

[0085] The radius of curvature of each curved surface (first curved surface CS1 to fourth curved surface CS4) relates to the shape formed as a result of polishing and grinding the base material of the electrostatic chuck member 10. Even if the conductive and insulating materials constituting the base material contain particles with a particle diameter larger than the radius of curvature of each curved surface and are placed on any of the curved surfaces, the shape and particle diameter of such particles will change due to polishing and grinding. Therefore, the radius of curvature of each curved surface does not depend on the particle diameter of the base material.

[0086] The radius of curvature of each curved surface is determined by the following method. First, in a plan view, the smallest circle circumscribing the electrostatic chuck member is assumed, and the electrostatic chuck member is cut by a virtual plane that includes the center of this circle and is perpendicular to the first mounting surface. At this time, the cutting position is adjusted so that the part of the electrostatic chuck member to be measured (convex curved surface) is included in the cutting plane. The cross-section may also be ground with a grinding wheel of 1000 grit or higher.

[0087] Next, a magnified photograph of the obtained cross-section is taken. The magnification is set according to the size of the convex surface to be measured by observing it with a stereoscope. The magnification is such that the radius of curvature can be appropriately measured from the obtained photograph, and is appropriately selected from a range such as 40x to 200x. The radius of curvature of the convex surface is measured from the obtained magnified photograph.

[0088] The measurement method described above is also used when measuring the radius of curvature of a concave surface, as will be discussed later.

[0089] The electrostatic chuck member 10 may have a first curved surface CS1 and a second curved surface CS2 formed on a part of the circumferential direction of the first side circumferential surface 21b, or it may have the first curved surface CS1 and the second curved surface CS2 formed on the entire circumferential direction. Furthermore, the curvature of the first curved surface CS1 and the second curved surface CS2 may be constant in the circumferential direction, or it may be different in the circumferential direction.

[0090] Furthermore, the electrostatic chuck member 10 may have a third curved surface CS3 and a fourth curved surface CS4 formed on a part of the circumferential direction of the second side circumferential surface 22b, or it may have the third curved surface CS3 and the fourth curved surface CS4 formed on the entire circumferential direction. Also, the curvature of the third curved surface CS3 and the fourth curved surface CS4 may be constant in the circumferential direction, or it may be different in the circumferential direction.

[0091] (Area of ​​the convex curved surface) As shown in Figure 5, it is preferable that the electrostatic chuck member 10 satisfies the following equation (2): L1 < L2 ... (2) (L1: Length of the first imaginary line VL1 connecting the upper end P1 of the first curved surface CS1 and the lower end P2 of the second curved surface CS2 L2: Length of the second imaginary line VL2 connecting the upper end P3 of the third curved surface CS3 and the lower end P4 of the fourth curved surface CS4)

[0092] As described above, in conventional electrostatic chuck members, the electrostatic field tends to concentrate at the upper corners of the side surfaces. Even when curved surfaces are formed on the upper parts of the first side surface 21b and the second side surface 22b, as in the electrostatic chuck member 10 of this embodiment, it is considered that the property of the electrostatic field tending to concentrate at the upper parts of each side surface compared to the surrounding area remains unchanged.

[0093] Therefore, in the electrostatic chuck member 10, it is preferable that the second processed surface (third curved surface CS3, second inclined surface 22c, fourth curved surface CS4) at the end of the second adsorption portion 22 is wider than the first processed surface (first curved surface CS1, first inclined surface 21c, second curved surface CS2) at the end of the first adsorption portion 21. In this relationship, charged foreign particles adhering to the second processed surface will be more dispersed than charged foreign particles adhering to the first processed surface, thereby suppressing the accumulation of charged foreign particles on the second side surface 22b.

[0094] Since it is difficult to directly compare the areas of the first and second processed surfaces, we compare the lengths L1 and L2 of the virtual lines mentioned above as corresponding numerical values.

[0095] (Elevation angle relative to the electrode end) As shown in Figure 6, it is preferable that the electrostatic chuck member 10 satisfies the following equation (3): θ2 < θ1 ... (3) (θ1: Elevation angle of the midpoint VP1 of the first imaginary line VL1 relative to the end 13p on the first side surface 21b of the first electrode 13 θ2: Elevation angle of the midpoint VP2 of the second imaginary line VL2 relative to the end 15p on the second side surface 22b of the second electrode 15)

[0096] By making the elevation angle θ2 smaller than the elevation angle θ1, the electric field strength directed toward the second inclined surface 22c and the second side surface 22b can be made smaller than the electric field strength directed toward the first inclined surface 21c and the first side surface 21b. As a result, the number of charged foreign particles attracted to the second inclined surface 22c and the second side surface 22b can be reduced compared to the first inclined surface 21c and the first side surface 21b, thereby suppressing the accumulation of charged foreign particles.

[0097] Figure 7 is a partial cross-sectional view showing an electrostatic chuck member 10B according to a modified example. In the electrostatic chuck member 10B shown in Figure 7, the first side circumferential surface 21b and the second mounting surface 22a are connected by a concave curved surface CS5. Preferably, the radius of curvature r5 of the concave curved surface CS5 is larger than the radii of curvature r1 to r4 of the first curved surface CS1, the second curved surface CS2, the third curved surface CS3, and the fourth curved surface CS4.

[0098] In the electrostatic chuck member 10B with the above configuration, the connection point between the first circumferential surface 21b and the second mounting surface 22a is more easily plasma-cleaned compared to a configuration where, for example, the first circumferential surface 21b and the second mounting surface 22a are perpendicular to each other. Therefore, the occurrence of abnormal discharge can be suppressed.

[0099] With the electrostatic chuck members 10 and 10B configured as described above, the adhesion of charged foreign particles to the second circumferential surface 22b can be suppressed, and problems (reduced productivity, dielectric breakdown) caused by the adhesion of charged foreign particles to the second circumferential surface 22b can be reduced.

[0100] 《Electrostatic Chuck Device》 Figure 8 is a cross-sectional view showing the electrostatic chuck device of this embodiment. The electrostatic chuck device 1A includes the electrostatic chuck member 10 described above, a disc-shaped base 3 that cools the electrostatic chuck member 10 and adjusts it to a desired temperature, and a bonding layer 4 that joins and integrates the electrostatic chuck member 10 and the base 3.

[0101] <Base> The base 3 is a disc-shaped member in plan view and supports the electrostatic chuck member 10 from below (the other side in the stacking direction). The upper surface (support surface) 3a of the base 3 faces the lower surface 11a of the electrostatic chuck member 10 in the vertical direction (stacking direction) via the bonding layer 4. The base 3 supports the electrostatic chuck member 10 at its support surface 3a.

[0102] A flow path 3f for circulating a refrigerant may be provided inside the base 3. The refrigerant flowing through the flow path 3f may be a fluorine-based inert liquid, water, He gas, N ２ Gases or the like are used. The flow path 3f extends along the support surface 3a. The refrigerant in the flow path 3f cools the entire base 3 and also cools the electrostatic chuck member 10 via the support surface 3a. In other words, the base 3 functions as a temperature control member for the electrostatic chuck member 10.

[0103] The base 3 is connected to an external high-frequency power supply 5 via a matching circuit (not shown) and also serves as an internal electrode for plasma generation.

[0104] The material of the base 3 is not limited as long as it is a metal with excellent thermal conductivity, electrical conductivity, and workability, or a composite material containing such metals, or a ceramic with high thermal conductivity, a conductive ceramic, or a metal-ceramic composite material (MMC: Metal Matrix Composition). Suitable materials for the base 3 include, for example, aluminum (Al), aluminum alloys, copper (Cu), copper alloys, stainless steel (SUS), and ceramics composed of a high thermal conductivity material and a conductive material. The ceramic may, for example, have a volume ratio of 10:90 to 90:10 between the high thermal conductivity material and the conductive material, and may be composed of AlN and TiN, AlN and Mo, or AlN, TiN, and Mo.

[0105] Preferably, at least the surface of the base 3 that is exposed to the plasma is anodized or has an insulating film such as alumina deposited on it.

[0106] <Bonding Layer> The bonding layer 4 can be made of known bonding materials, and may be formed of organic adhesives such as polyimide resin, silicone resin, and epoxy resin. These organic adhesives have heat resistance and insulating properties after bonding and curing. Among organic adhesives, the bonding layer 4 is preferably formed of a silicone adhesive. Silicone adhesives have a low glass transition temperature, a high heat resistance temperature, and rubber elasticity. It is preferable that insulating ceramic powder (aluminum oxide, aluminum nitride, etc.) is added to this silicone adhesive as a thermally conductive filler.

[0107] Furthermore, the material of the bonding layer 4 may be a metal brazing material or a ceramic.

[0108] The base 3, bonding layer 4, and materials described above are merely examples; any base and bonding layer used in known electrostatic chuck devices can be appropriately adopted.

[0109] Furthermore, the electrostatic chuck device 1A may appropriately adopt known configurations as components of an electrostatic chuck device, as long as they do not impair the effects of the invention.

[0110] According to the electrostatic chuck device 1A of this embodiment, since it has the electrostatic chuck member 10 described above, the occurrence of dielectric breakdown (discharge) on the side surface of the electrostatic chuck member can be suppressed.

[0111] 《Semiconductor Manufacturing Apparatus》 Figure 9 is an explanatory diagram of a semiconductor manufacturing apparatus having the electrostatic chuck device described above. The semiconductor manufacturing apparatus 1000 includes an electrostatic chuck device 1A, a vacuum chamber 200, an upper electrode 300, a magnet 400, a gas supply means 500, a vacuum pump 600, and a plasma stabilization system 700.

[0112] The vacuum chamber 200 houses the electrostatic chuck device 1A and is used as a reaction field for performing plasma processing inside. The vacuum chamber 200 can employ a known configuration used in semiconductor manufacturing equipment. The vacuum chamber 200 has a gate (not shown) for inserting and removing plate-shaped samples W.

[0113] The upper electrode 300 is housed within the vacuum chamber 200 and is a counter electrode used in cooperation with the electrostatic chuck device 1A when generating plasma within the vacuum chamber 200. The upper electrode 300 is connected to a power supply (not shown).

[0114] The magnet 400 is positioned around the vacuum chamber 200 and generates a vertical magnetic field in the space between the upper electrode 300 inside the vacuum chamber 200 and the electrostatic chuck device 1A.

[0115] The gas supply means 500 supplies plasma gas G into the vacuum chamber 200. The gas supply means 500 supplies plasma gas G into the vacuum chamber 200, for example, from a gas hole provided in the upper electrode 300.

[0116] The vacuum pump 600 exhausts the gas from the vacuum chamber 200 and prepares the atmosphere for plasma generation. The vacuum pump 600 is connected, for example, below the electrostatic chuck device 1A in the vacuum chamber 200.

[0117] The plasma stabilization system 700 stabilizes the plasma state by detecting and compensating for various external factors that cause fluctuations in the plasma state generated in the semiconductor manufacturing apparatus 1000. The plasma stabilization system 700 includes a detector 710 and a control unit 720 that controls the semiconductor manufacturing apparatus 1000 based on the detection results from the detector 710.

[0118] The detector 710 directly or indirectly detects the state of the plasma inside the vacuum chamber 200. There may be one detector 710 or multiple detectors. Examples of items detected by the detector 710 include the vacuum level inside the vacuum chamber 200, the color of the plasma, the temperature of the plasma, the capacitance between the upper electrode 300 and the internal plasma generating electrode (not shown) of the electrostatic chuck device 1A, and the inductance between the upper electrode 300 and the internal plasma generating electrode.

[0119] The control unit 720 controls the semiconductor manufacturing apparatus 1000 based on the detected values ​​of each item detected by the detector 710, or the rate of change of the detected values ​​per unit time. The control unit 720 stores in advance the correspondence between the detected values ​​of the above items and the state of the plasma generated in the vacuum chamber 200. Based on the detected values ​​and the above correspondence, the control unit 720 performs feedback control of the semiconductor manufacturing apparatus 1000 so that the state of the plasma falls within a predetermined range. Examples of items to be feedback controlled include the temperature, vacuum level, and bias voltage inside the semiconductor manufacturing apparatus.

[0120] As a result, the plasma stabilization system 700 can suppress long-term fluctuations in the plasma state of the semiconductor manufacturing apparatus 1000 and stabilize the state.

[0121] Such plasma stabilization systems are effective in suppressing long-term fluctuations in the plasma state throughout the entire manufacturing process using semiconductor manufacturing equipment. On the other hand, plasma stabilization systems were not effective in suppressing state fluctuations caused by extremely short-term fluctuation factors, such as abnormal discharges during wafer processing.

[0122] On the other hand, since the semiconductor manufacturing apparatus 1000 has the electrostatic chuck device 1A described above, it can suppress abnormal discharges that occur in the wafer during the process. Therefore, by having the plasma stabilization system 700, the semiconductor manufacturing apparatus 1000 can stabilize the plasma both in the long term and in the short term.

[0123] The control unit 720 may be a configuration specific to the plasma stabilization system 700, and the control unit that controls the semiconductor manufacturing apparatus 1000 may also perform the same function.

[0124] In such a semiconductor manufacturing apparatus 1000, for example, the tendency for charged foreign particles to adhere to the side surface of the electrostatic chuck member 10 may differ depending on the position of the exhaust port of the vacuum chamber 200 (the connection position of the vacuum pump 600). If the above tendency is empirically known for the semiconductor manufacturing apparatus 1000, the electrostatic chuck member 10 should adopt a configuration that suppresses the adhesion of charged foreign particles, such as making the arithmetic mean roughness Ra smaller on the side surface at the position where charged foreign particles are likely to adhere compared to the other side surfaces.

[0125] According to the semiconductor manufacturing apparatus 1000 of this embodiment, since it has the electrostatic chuck device 1A described above, the occurrence of dielectric breakdown (discharge) can be suppressed.

[0126] Furthermore, the semiconductor manufacturing apparatus 1000 suppresses abnormal discharge (short-term fluctuations in plasma) with the electrostatic chuck device 1A, and suppresses long-term fluctuations in plasma with the plasma stabilization system 700. As a result, stable plasma processing is possible, and the semiconductor manufacturing apparatus can be made to have improved yield.

[0127] Although preferred embodiments of the present invention have been described above with reference to the attached drawings, the present invention is not limited to these examples. The shapes and combinations of the constituent members shown in the above examples are merely examples, and can be modified in various ways based on design requirements, etc., without departing from the spirit of the present invention. Furthermore, although silicon wafers were used in the above description, it is clear that the wafers that can be processed by the electrostatic chuck member of the present invention may be made of materials other than silicon, such as indium phosphate-based wafers, gallium arsenide-based wafers, or other materials.

[0128] This invention provides an electrostatic chuck member and electrostatic chuck device that can reduce problems caused by the adhesion of charged foreign particles to the side surface.

[0129] 1A Electrostatic chuck device 11a Bottom surface 3a Top surface (support surface) 3f Flow path 10, 10B Electrostatic chuck member 11 Base body 13 First electrode 13p, 15p End portion 15 Second electrode 21 First adsorption part 21a First mounting surface 21b First side surface 21c First inclined surface 21x Flow path 211 Protrusion 212 Annular protrusion 22 Second adsorption part 22a Second mounting surface 22b Second side surface 22x Groove 3 Base 4 Bonding layer 5 High-frequency power supply 200 Vacuum chamber 300 Upper electrode 400 Magnet 500 Gas supply means 600 Vacuum pump 700 Plasma stabilization system 710 Detector 720 Control unit 1000 Semiconductor manufacturing equipment CS1 First curved surface CS2 Second surface CS3 Third surface CS4 Fourth surface CS5 Concave surface d1, d2 Thickness FR Focus ring FR1 Support part FR2 Protruding part G Plasma gas L1, L2 Length P1, P2, P3, P4 End r1, r2, r3, r4, r5 Radius of curvature S1, S2, S3, S4 Virtual surface t1, t2 Height VL1 First virtual line VL2 Second virtual line VP1, VP2 Midpoint W Plate-shaped sample W1 Width θ1, θ2 Elevation angle

Claims

1. An electrostatic chuck member comprising a substrate made of a dielectric material and an electrostatic adsorption electrode provided inside the substrate, wherein the substrate has a first adsorption portion whose upper surface is a first mounting surface on which a plate-shaped sample is placed, and a second adsorption portion formed in a closed annular shape below the first adsorption portion and outside the first adsorption portion in a plan view, with the upper surface being a second mounting surface on which a focus ring is placed, and the electrostatic adsorption electrode includes a first electrode provided in the first adsorption portion and a second electrode provided in the second adsorption portion, wherein the first side circumferential surface of the substrate continuous with the first mounting surface has a first curved surface which is a convex curved surface provided in the circumferential direction at the periphery of the first mounting surface and a second curved surface provided in the circumferential direction at a height position different from the first curved surface, and the second side circumferential surface continuous with the second mounting surface has a third curved surface which is a convex curved surface provided in the circumferential direction at the periphery of the second mounting surface, The electrostatic chuck member has a fourth curved surface provided in the circumferential direction at a height position different from the third curved surface, and the electrostatic chuck member satisfies the following formula (1): W1 > t1 + t2 ... (1) (W1: width of the second suction part t1: height from the second mounting surface to the first mounting surface t2: height from the bottom surface of the base to the second mounting surface) 2. The electrostatic chuck member according to claim 1, wherein the radius of curvature of the first curved surface and the radius of curvature of the second curved surface are both greater than the thickness of the first electrode, and the radius of curvature of the third curved surface and the radius of curvature of the fourth curved surface are both greater than the thickness of the second electrode.

3. The electrostatic chuck member according to claim 1 or 2, wherein the first circumferential surface and the second mounting surface are connected by a concave curved surface.

4. The electrostatic chuck member according to claim 3, wherein the radius of curvature of the concave curved surface is greater than the radius of curvature of any of the first, second, third, and fourth curved surfaces.

5. An electrostatic chuck member according to claim 1 or 2 that satisfies the following formula (2): L1 < L2 ... (2) (L1: length of a first imaginary line connecting the upper end of the first curved surface and the lower end of the second curved surface L2: length of a second imaginary line connecting the upper end of the third curved surface and the lower end of the fourth curved surface) 6. An electrostatic chuck member according to claim 1 or 2 that satisfies the following formula (3): θ2 < θ1 ... (3) (θ1: An elevation angle of the midpoint of a first imaginary line connecting the upper end of the first curved surface and the lower end of the second curved surface, with reference to the end of the first side surface of the first electrode. θ2: An elevation angle of the midpoint of a second imaginary line connecting the upper end of the third curved surface and the lower end of the fourth curved surface, with reference to the end of the second side surface of the second electrode.) 7. An electrostatic chuck device comprising: an electrostatic chuck member according to claim 1 or 2; and a base member for cooling the electrostatic chuck member and adjusting the temperature of the electrostatic chuck member.

Images