Electrostatic chuck member and electrostatic chuck device

Abstract

Provided is an electrostatic chuck member comprising: a substrate in which a dielectric material is used as a forming material; and an electrostatic attraction electrode provided inside of the substrate. The substrate has: a first attraction part of which the upper surface is a first placement surface on which a plate-like sample is placed; and a second attraction part which is formed below the first attraction part in a closed ring shape on the outside of the first attraction part in plan view and of which the upper surface is a second placement surface on which a focus ring is placed. Furthermore, the electrostatic attraction electrode includes a first electrode provided on the first attraction part and a second electrode provided on the second attraction part, and satisfies expressions (1) and (2).　Expression (1): L1 < L2 Expression (2): t1 < t2 (L1: the shortest distance between the first electrode and the corner portion between the first placement surface and a first side peripheral surface, L2: the shortest distance between the electrode of the section attraction part and the corner portion between the second placement surface and a second side peripheral surface, t1: the height of the first side peripheral surface, and t2: the height of the second side peripheral 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. 2025-053938, 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, wherein the electrostatic chuck member satisfies the following formulas (1) and (2). L1 < L2 ... (1) t1 < t2 ... (2) (L1: The shortest distance between the corner between the first mounting surface and the first side surface which is the side surface of the first adsorption part, and the first electrode L2: The shortest distance between the corner between the second mounting surface and the second side surface which is the side surface of the second adsorption part, and the electrode provided by the second adsorption part t1: Height of the first side surface t2: Height of the second side surface)

[0012] [2] The electrostatic chuck member described in [1] that satisfies the following formula (3): [width of the second adsorption portion] / t1 ≥ 2 ... (3)

[0013] [3] The electrostatic chuck member according to [1] or [2], wherein the first mounting surface is circular in plan view and satisfies the following formula (4): [radius of the first mounting surface] / [width of the second suction part] ≤ 20 ... (4)

[0014] [4] An electrostatic chuck member according to any one of items [1] to [3] that satisfies the following formula (5): [Area of ​​the second side surface] / [Area of ​​the first side surface] ≥ 1.2 ... (5)

[0015] [5] An electrostatic chuck member according to any one of [1] to [4] that satisfies the following formula (6). [Width of the second adsorption portion] > (t2 - t1) × [Relative permittivity of the dielectric material] ... (6)

[0016] An electrostatic chuck device comprising an electrostatic chuck member as described in any one of items [6], [1] to [5], and a base member that cools the electrostatic chuck member and adjusts the temperature of the electrostatic chuck member.

[0017] 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.

[0018] 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 a cross-sectional view showing the electrostatic chuck device 1A of this embodiment. Figure 5 is an explanatory diagram of a semiconductor manufacturing apparatus 1000 having the electrostatic chuck device described above.

[0019] A known electrostatic chuck device (electrostatic chuck member) has a configuration that includes a first adsorption part that adsorbs and holds a wafer, which is the object to be processed, on its upper surface, and a second adsorption part that adsorbs and holds a focus ring on its upper surface.

[0020] A "focus ring" is a circular component in electrostatic chuck equipment that surrounds the outer circumference of a wafer in plan view. The focus ring plays a role in maintaining a uniform electrical environment between the periphery and the center of the wafer during plasma processing. The focus ring is made of the same material as the wafer and partially overlaps with the wafer in plan view, thereby extending the electrical environment in the radial direction of the wafer.

[0021] Due to the above function, the upper surface of the second adsorption portion that holds the focus ring is formed lower than the upper surface of the first adsorption portion that adsorbs the wafer. As a result, there are two sides of the electrostatic chuck member with the above configuration: the side of the first adsorption portion (sometimes referred to as the "first side surface" in this specification) and the side of the second adsorption portion (sometimes referred to as the "second side surface" in this specification).

[0022] The inventors of the present invention 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 for each process of processing a wafer. The generation center of this plasma is 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.

[0023] As a result of intensive studies conducted by the inventors based on the above findings, the inventors arrived at the idea that the problem can be solved by providing an electrostatic chuck member having a shape and configuration capable of reducing charged foreign particles adhering to the second side peripheral surface, and completed the present invention.

[0024] Hereinafter, an electrostatic chuck member according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3. In all of the following drawings, the dimensions and ratios of respective components are appropriately changed to make the drawings easier to see.

[0025] <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 II-II in FIG. 1 in the direction of the arrow. FIG. 2 shows a state where a focus ring FR is placed on the electrostatic chuck member 10.

[0026] As shown in FIGS. 1 and 2, the electrostatic chuck member 10 includes a base body 11 formed of a dielectric material, and an electrostatic chuck electrode provided inside the base body.

[0027] The cross-sectional view shown in FIG. 2 is a cross-section obtained by cutting the electrostatic chuck member along a virtual plane including the center of the smallest circle circumscribing the electrostatic chuck member 10 in plan view. In other words, FIG. 2 is a cross-sectional view taken along a cross section passing through the center C of the base body (first mounting surface 21a) and including 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 circle substantially coincides with the center of the shape of the electrostatic chuck member in plan view.

[0028] Note that, in the present specification, the term "plan view" refers to a visual field viewed from the y-direction, which is the thickness direction of the electrostatic chuck member. Furthermore, the term "cross-sectional view" refers to a visual field in a direction orthogonal to a cross-section obtained when cutting along a virtual plane including the center of the smallest circle assumed among circles circumscribing the electrostatic chuck member that are perpendicular to the mounting surface and viewed in plan view.

[0029] (Base Body) The base body 11 includes a first suction portion 21 and a second suction portion 22. The first suction portion 21 and the second suction portion 22 are formed in a concentric pattern with a center C being concentric when viewed in plan view.

[0030] The first suction portion 21 is formed in a columnar shape (or a disc shape), and includes a first mounting surface 21a that is an upper surface, and a first side peripheral surface 21b continuous with the first mounting surface 21a.

[0031] In the electrostatic chuck member 10 of the present embodiment, the first mounting surface 21a is provided with a plurality of upward-protruding convex portions 211. Furthermore, a closed-ring-shaped annular convex portion 212 is provided along the edge of the upper surface of the first suction portion 21 on the peripheral edge portion of the upper surface of the first suction portion 21.

[0032] The first suction portion 21 supports a plate-shaped sample (wafer, not shown) on the tip portions (upper surfaces) of the plurality of convex portions 211 and the upper surface of the annular convex portion 212. That is, in the first suction portion 21, a virtual plane connecting the upper surface of the annular convex portion 212 and the upper surfaces of the plurality of convex portions 211 is the first mounting surface 21a on which the plate-shaped sample is mounted. Furthermore, when the virtual plane set in this way is a concave surface or a convex surface, the mean square plane of the virtual plane is defined as the first mounting surface 21a.

[0033] The plate-shaped sample mounted on the first mounting surface 21a is in contact with and supported by the upper surfaces of the convex portions 211 constituting the first mounting surface 21a and the upper surface of the annular convex portion 212. At this time, the space surrounded by the lower surface of the plate-shaped sample, the plurality of convex portions 211, and the annular convex portion 212 functions as a flow path 21x for flowing cooling gas.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] Furthermore, the second suction portion 22 has a second circumferential surface 22b that is continuous with the second mounting surface 22a.

[0038] (Electrodes for electrostatic adsorption) The electrodes for electrostatic adsorption include a first electrode 13 provided on the first adsorption part 21 and a second electrode 15 provided on the second adsorption part 22. The first electrode 13 is an electrode that generates an electrostatic adsorption force on the first mounting surface 21a. The second electrode 15 is an electrode that generates an electrostatic adsorption force on the second mounting surface 22a.

[0039] In Figure 2, the base body 11 is shown as a single component spanning the first adsorption portion 21 and the second adsorption portion 22, but it is not limited to this. The base body 11 may be a laminate formed by stacking multiple ceramic plates and bonding the ceramic plates together with an adhesive or an inorganic bonding agent.

[0040] (Substrate) The substrate 11 is formed from a dielectric material. The dielectric material may be composed of an insulating material, or it may be composed of a composite material of an insulating material and a conductive material.

[0041] The insulating material included in the substrate 11 is not particularly limited, but for example, 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.

[0042] 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.

[0043] The material of the base body 11 has a volume resistivity value of 10 １３ Ω·cm or more and 10 １７ Ω·cm or less, and is not particularly limited as long as it is a material having mechanical strength and durability against corrosive gas and plasma thereof. Examples of such a material include Al ２ O ３ sintered bodies, AlN sintered bodies, Al ２ O ３ -SiC composite sintered bodies, and the like. From the viewpoints of dielectric properties at high temperature, high corrosion resistance, plasma resistance and heat resistance, the material of the base body 11 is Al ２ O ３ -SiC composite sintered body is preferable.

[0044] The average primary particle diameter of the insulating material constituting the base body 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 still more preferably 1.0 μm or more and 2.0 μm or less.

[0045] When the average primary particle diameter of the insulating material constituting the base body 11 is 0.5 μm or more and 3.0 μm or less, a dense base body 11 having high voltage resistance and high durability can be obtained.

[0046] 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.

[0047] (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.

[0048] 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.

[0049] 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.

[0050] (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".

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] Examples of carbon materials include carbon black, carbon nanotubes, and carbon nanofibers.

[0057] Examples of conductive composite sintered bodies include Al ２O ３ -Ta ４ C ５ Al ２ O ３ -W, Al ２ O ３ Examples include SiC, AlN-W, and AlN-Ta.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] (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.

[0065] The electrostatic chuck member 10 satisfies the following equations (1) and (2): L1 < L2 ... (1) t1 < t2 ... (2) (L1: the shortest distance between the corner E1 where the first mounting surface 21a and the first side circumferential surface 21b intersect and the first electrode 13 L2: the shortest distance between the corner E2 where the second mounting surface 22a and the second side circumferential surface 22b intersect and the electrode provided by the second adsorption part 22 t1: height of the first side circumferential surface 21b, t2: height of the second side circumferential surface 22b)

[0066] Furthermore, if wear occurs during use or if chamfering is performed during manufacturing, a curved or slanted surface may be formed between the first mounting surface 21a and the first side circumferential surface 21b, making the corner E1 unclear in the same cross-sectional view as in Figure 3. In such cases, it is advisable to consider a virtual line extending in contact with the first mounting surface 21a and another virtual line extending in contact with the first side circumferential surface 21b in the same cross-sectional view, and to consider the point where these two virtual lines intersect as a virtual corner E1.

[0067] Distance L1 corresponds to the length of the portion of the straight line that overlaps with the base body 11, assuming a straight line connecting the virtual angle E1 and the first electrode 13.

[0068] Even when the angle E2 is unclear, by applying the above concepts of angle E1 and distance L1, a hypothetical angle E2 can be considered and distance L2 can be defined.

[0069] Here, "electrodes provided by the second adsorption unit 22" refers to all electrodes that the second adsorption unit 22 has. If the second adsorption unit 22 has only one second electrode 15, as shown in Figure 2, then the second electrode 15 is referred to.

[0070] If the second adsorption part 22 has multiple electrodes, the electrode closest to the corner E2 among all the electrodes provided by the second adsorption part 22 corresponds to the "electrode provided by the second adsorption part" at distance L2. "Having multiple electrodes" can refer to cases such as when the electrostatic adsorption electrode is bipolar, or when there is a heater electrode in addition to the electrostatic adsorption electrode.

[0071] "The height t1 of the first side surface 21b" can also be rephrased as the height from the second mounting surface 22a to the first mounting surface 21a. Similarly, "the height t2 of the second side surface 22b" can also be rephrased as the height from the bottom surface 11a of the base 11 to the second mounting surface 22a.

[0072] The above equations (1) and (2) can be understood as follows. First, when a voltage is applied to the electrostatic adsorption electrodes (first electrode 13, second electrode 15) of the electrostatic chuck member 10 to generate an electric field, charged foreign particles floating in the space around the electrostatic chuck member are attracted to the electrostatic chuck member 10 along the generated electric field.

[0073] Normally, charged foreign particles are assumed to repeatedly adsorb and detach from the surface of electrostatic chuck members during wafer processing. When the amount of charged foreign particles adhering per unit surface area increases, it is assumed that the charged foreign particles will adsorb and detach from the surface of the electrostatic chuck member as aggregates. When such aggregates adsorb and detach from the surface of the electrostatic chuck member, it is thought that "abnormal discharge" occurs, which can cause dielectric breakdown.

[0074] In this electrostatic chuck member 10, there are two corners: corner E1 of the first adsorption part 21 and corner E2 of the second adsorption part 22. Therefore, the electric field generated in the space surrounding the electrostatic chuck member tends to concentrate at corners E1 and E2, which have a relative permittivity that is relatively larger than the permittivity of the surrounding space. As a result, charged foreign particles tend to adhere to corners E1 and E2 and the side surfaces (first side surface 21b, second side surface 22b) near corners E1 and E2 in the electrostatic chuck member 10.

[0075] In this case, if the electrostatic chuck member 10 satisfies the above condition (1), even if the electric field strength generated by the first electrode 13 and the second electrode 15 is the same, the electric field strength at the corner E2, which is further from the electrode end, is relatively weaker than the electric field strength at the corner E1, which is closer to the electrode end than the corner E2. Therefore, the corner E2 is less likely to attract foreign charged particles than the corner E1. As a result, charged foreign particles are less likely to accumulate at the corner E2 and the second side surface 22b than at the corner E1 and the first side surface 21b.

[0076] The Coulomb force that attracts foreign charged particles to the corners E1 and E2 is inversely proportional to the square of the distance between the corner and the foreign charged particles. Therefore, making L2 larger than L1 is very effective in suppressing the amount of charged foreign particles that accumulate at the corners E2 and the second side surface 22b.

[0077] When the second adsorption section 22 has multiple electrodes, the electric field generated by the electrostatic adsorption electrodes also electrically affects each electrode, and the resulting electric field converges on each electrode. At this time, it is thought that charged foreign particles attracted to the corner E2 are affected by the electric field that converges on the electrode closest to the corner E2. Therefore, when the second adsorption section 22 has multiple electrodes, the above (1) is determined based on the distance between the electrode closest to the corner E2 and the corner E2 among all the electrodes provided by the second adsorption section 22.

[0078] Furthermore, if the electrostatic chuck member 10 satisfies the above condition (2), even if the same amount of charged foreign particles adhere to both the first circumferential surface 21b and the second circumferential surface 22b, the charged foreign particles tend to accumulate more easily on the second circumferential surface 22b, dispersing in the height direction. Therefore, aggregates of charged foreign particles are less likely to form on the second circumferential surface 22b than on the first circumferential surface 21b, and abnormal discharges are less likely to occur.

[0079] Due to these effects, the electrostatic chuck member 10 that satisfies (1) and (2) above can suppress dielectric breakdown caused by charged foreign particles, and can also superimpose the suppression of dielectric breakdown caused by ions and electrons.

[0080] In equation (1), L1 and L2 are preferably L2 / L1 > 1.0, more preferably L2 / L1 ≥ 1.2, and even more preferably L2 / L1 ≥ 1.5. On the other hand, L2 and L1 are preferably L2 / L1 ≤ 2.5.

[0081] In equation (2), it is preferable that t2 / t1 > 1.0, more preferably that t2 / t1 ≥ 1.2, and even more preferably that t2 / t1 ≥ 1.5. On the other hand, it is preferable that t2 / t1 ≤ 2.5.

[0082] Furthermore, the electrostatic chuck member 10 is preferably configured as follows.

[0083] The electrostatic chuck member 10 preferably satisfies the following formula (3): [Width W1 of the second suction part 22] / t1 ≥ 2 …(3)

[0084] 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.

[0085] 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 (3) has a sufficiently wide width W1 of the second adsorption part 22, which can reduce the impact of abnormal discharge.

[0086] It is preferable that W1 / t1 ≥ 5, and more preferably that W1 / t1 ≥ 10. On the other hand, it is preferable that W1 / t1 ≤ 20.

[0087] The width W1 can also be expressed in relation to the radius R of the first mounting surface 21a. The dimensions of the electrostatic chuck member 10 when viewed from above preferably satisfy the following equation (4): [Radius R of the first mounting surface 21a] / [Width W1 of the second suction part 22] ≤ 20 …(4)

[0088] If the first suction portion 21 is circular in plan view, the radius R of the first mounting surface 21a can also be considered as the radius of the first suction portion 21.

[0089] The radius R is determined by the size of the plate-shaped sample being processed, and is therefore a predetermined value in the design of the apparatus. The inventors propose that by setting the radius R to 20 times or less the width W1, the effects of abnormal discharge can be reduced.

[0090] R and W1 are preferably R / W1 ≤ 15, and more preferably R / W1 ≤ 10. On the other hand, R and W1 are preferably R / W1 ≥ 5.

[0091] The electrostatic chuck member 10 preferably satisfies the following formula (5): [Area S2 of the second circumferential surface 22b] / [Area S1 of the first circumferential surface 21b] ≥ 1.2 … (5)

[0092] While equation (2) above specifies the relationship between the heights of each side surface, equation (5) more specifically specifies a comparison between the areas of each side surface. If the electrostatic chuck member 10 satisfies equation (5) above, even if the same amount of charged foreign particles adhere to both the first side surface 21b and the second side surface 22b, the charged foreign particles will be more dispersed within the surface of the second side surface 22b. Therefore, aggregates of charged foreign particles are less likely to form on the second side surface 22b than on the first side surface 21b, and abnormal discharges are less likely to occur.

[0093] Preferably, S2 / S1 ≥ 1.3, and more preferably, S2 / S1 ≥ 1.5. On the other hand, preferably, S2 / S1 ≤ 3.0.

[0094] The above equation (5) can be adjusted by adjusting the heights of the first and second side surfaces, and the shape of the second side surface in a plan view.

[0095] If an electrostatic chuck having a first suction part and a second suction part formed concentrically in a plan view does not satisfy equation (5), then, for example, the design can be made to satisfy the relationship of equation (5) by changing the "shape of the second side surface" as follows: (i) Expand the radius of the second side surface. (ii) Make the plan view shape of the second suction part a shape in which the current plan view shape of the second suction part (circular) is partially inscribed.

[0096] In (ii) above, the “partially inscribed shape” may be an ellipse or a polygon.

[0097] The electrostatic chuck member 10 preferably satisfies the following formula (6): [Width W1 of the second adsorption part 22] > (t2 - t1) × εr …(6) (εr: relative permittivity of the dielectric material which is the material of the substrate 11)

[0098] The right-hand side of equation (6) above corresponds to the effective spatial distance of the second circumferential surface 22b. When a discharge occurs on the second circumferential surface 22b, it is considered effective to maximize the spatial separation distance between the discharge initiation point and the plate-shaped sample in order to reduce the effect of the discharge on the plate-shaped sample supported by the first adsorption part 21. The above separation distance corresponds to the width W1 of the second adsorption part 22.

[0099] It is preferable to make the above-mentioned separation distance larger than the effective spatial distance of the second side surface 22b (the right-hand side of equation (6)) to reduce the effect of discharge. The relative permittivity εr is, for example, about 13 (at 1 MHz) when the material of the substrate 11 is SiC.

[0100] With the electrostatic chuck member 10 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.

[0101] 《Electrostatic Chuck Device》 Figure 4 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.

[0102] <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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] <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.

[0108] Furthermore, the material of the bonding layer 4 may be a metal brazing material or a ceramic.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 《Semiconductor Manufacturing Apparatus》 Figure 5 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.

[0113] 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.

[0114] 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).

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] 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.

[0130] 1A Electrostatic chuck device 11a Bottom surface 3a Top surface (support surface) 3f Flow channel 10 Electrostatic chuck member 11 Base body 13 First electrode 15 Second electrode 21 First adsorption part 21a First mounting surface 21b First side surface 21x Flow channel 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 E1, E2 Corner FR Focus ring FR1 Support part FR2 Protrusion G Plasma gas L1, L2 Length t1, t2 Height W Plate-shaped sample W1 Width

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 its 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 electrostatic chuck member satisfies the following formulas (1) and (2). L1 < L2 ... (1) t1 < t2 ... (2) (L1: The shortest distance between the corner between the first mounting surface and the first side surface which is the side surface of the first adsorption part and the first electrode L2: The shortest distance between the corner between the second mounting surface and the second side surface which is the side surface of the second adsorption part and the electrode provided by the second adsorption part t1: The height of the first side surface t2: The height of the second side surface) 2. The electrostatic chuck member according to claim 1 that satisfies the following formula (3): [width of the second adsorption portion] / t1 ≥ 2 … (3) 3. The electrostatic chuck member according to claim 1 or 2, wherein the first mounting surface is circular in plan view and satisfies the following formula (4): [radius of the first mounting surface] / [width of the second suction part] ≤ 20 …(4) 4. The electrostatic chuck member according to claim 1 or 2, satisfying the following formula (5): [Area of ​​the second circumferential surface] / [Area of ​​the first circumferential surface] ≥ 1.2 … (5) 5. An electrostatic chuck member according to claim 1 or 2 that satisfies the following formula (6): [Width of the second adsorption portion] > (t2 - t1) × [Relative permittivity of the dielectric material] ... (6) 6. 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.

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