Electrostatic chuck member and electrostatic chuck device

Abstract

This electrostatic chuck member comprises: a disk-shaped dielectric substrate having a placement surface on which at least one adsorption target is placed; and a bipolar electrode that is disposed inside the dielectric substrate and electrostatically attracts the adsorption target to the placement surface. The bipolar electrode includes a first electrode and a second electrode which have different polarities from each other. The dielectric substrate is provided with a gas hole passing between the first electrode and the second electrode in the thickness direction of the dielectric substrate. The distance between the first electrode and the gas hole is greater than the distance between the second electrode and the gas hole, and the width dimension of the first electrode is larger than the width dimension of the second electrode.

Description

Electrostatic chuck member and electrostatic chuck device

[0001] This application claims priority to Japanese Patent Application No. 2024-093194, filed on June 7, 2024, the contents of which are incorporated herein by reference.

[0002] Conventionally, film deposition apparatuses and plasma etching apparatuses used in manufacturing semiconductor devices have stages for precisely holding a plate-shaped sample in a vacuum processing chamber. For example, an electrostatic chuck device has been proposed as such a stage, in which a plate-shaped sample is attracted and held by an electrostatic chuck member mounted on a base plate. Patent Document 1 (JP-A-2003-125566) discloses an electrostatic chuck member provided with a gas hole for supplying gas to the backside of the object to be attracted.

[0003] Japanese Patent Application Laid-Open No. 2021-93436

[0004] The inventors discovered that when the positive and negative electrodes of a bipolar electrode are arranged with a gas hole between them, a phenomenon in which mutually attracted charged particles collide with each other inside the gas hole (hereinafter referred to as mutually attracted discharge) may occur. Negatively charged particles attracted to the positive electrode adhere to the area of ​​the inner surface of the gas hole located on the positive electrode side. Similarly, positively charged particles attracted to the negative electrode adhere to the area of ​​the inner surface of the gas hole located on the negative electrode side. When the voltages of the positive and negative electrodes are high, the amount of these charged particles accumulated increases, and the accumulated charged particles repel each other. Eventually, some of the negatively charged particles accumulated on the positive electrode side may fly out, and some of the positively charged particles accumulated on the negative electrode side may fly out. If a negatively charged particle and a positively charged particle are released at the same time, these particles of opposite polarity will accelerate while attracting each other, and may collide inside the gas hole, causing a large abnormal discharge. If a mutual attraction discharge occurs, there is a concern that it may cause disturbances in the plasma used in semiconductor manufacturing, or that the heat generated during the collision may damage the object to be attracted, such as a plate-shaped sample.

[0005] The present invention has been made in view of the above circumstances, and provides an electrostatic chuck member and an electrostatic chuck device that can suppress collisions between charged particles of opposite polarities inside a gas hole.

[0006] The present invention includes the following [1] to [9]. It is also preferable to combine two or more of the following inventions as necessary. [1] An electrostatic chuck member comprising: a disk-shaped dielectric substrate having a mounting surface on which at least one object to be attracted is placed; and a bipolar electrode disposed inside the dielectric substrate and electrostatically attracting the object to be attracted to the mounting surface, the bipolar electrode including a first electrode and a second electrode having mutually opposite polarities, the dielectric substrate having a gas hole penetrating between the first electrode and the second electrode in a thickness direction of the dielectric substrate, the distance between the first electrode and the gas hole being greater than the distance between the second electrode and the gas hole, and the width dimension of the first electrode being greater than the width dimension of the second electrode. [2] An electrostatic chuck member comprising: a disk-shaped dielectric substrate having a mounting surface on which at least one object to be attracted is placed; and a bipolar electrode disposed inside the dielectric substrate and electrostatically attracting the object to be attracted to the mounting surface, wherein the bipolar electrode includes a first electrode and a second electrode having mutually opposite polarities; the dielectric substrate is provided with a gas hole penetrating between the first electrode and the second electrode in a thickness direction of the dielectric substrate; the distance between the first electrode and the gas hole is greater than the distance between the second electrode and the gas hole; the first electrode is located radially inward of the dielectric substrate with respect to the gas hole; and the second electrode is located radially outward of the gas hole. [3] The electrostatic chuck member according to [1] or [2], wherein the object to be attracted includes a plate-shaped sample and a focus ring, the mounting surface has: a first region on which the plate-shaped sample as the object to be attracted is mounted; and a second region which is annular and surrounds the first region when viewed in a thickness direction of the dielectric substrate and on which the focus ring as the object to be attracted is mounted, the bipolar electrode overlaps the second region when viewed in the thickness direction. [4] The electrostatic chuck member according to any one of [1] to [3], wherein, when a distance between the first electrode and the gas hole is d1, and a distance between the second electrode and the gas hole is d2, a gas hole position asymmetry ratio is a value represented by α in the following equation: α = (d1 - d2) / (d1 + d2), and the gas hole position asymmetry ratio satisfies 0 < α ≦ 0.95.[5] The electrostatic chuck member according to [1], wherein, when a width dimension of the first electrode is L1 and a width dimension of the second electrode is L2, a bipolar electrode asymmetry rate is defined as a value represented by β in the following equation, β=(L1-L2) / (L1+L2), wherein the bipolar electrode asymmetry rate satisfies 0<β≦0.95. [6] The electrostatic chuck member according to [1] or [5], wherein, when a distance between the first electrode and the gas hole is d1 and a distance between the second electrode and the gas hole is d2, a gas hole position asymmetry rate is defined as a value represented by α in the following equation, α=(d1-d2) / (d1+d2), wherein, when a width dimension of the first electrode is L1 and a width dimension of the second electrode is L2, a bipolar electrode asymmetry rate is defined as a value represented by β in the following equation, β=(L1-L2) / (L1+L2), wherein the gas hole position asymmetry rate and the bipolar electrode asymmetry rate satisfy the following equation, α>β. [7] The electrostatic chuck member according to any one of [1] to [6], wherein the following formula is satisfied: (d1 - d2) > R, where d1 is the distance between the first electrode and the gas hole, d2 is the distance between the second electrode and the gas hole, and R is the radius of the gas hole. [8] The distance between the first electrode and the gas hole is d1, the distance between the second electrode and the gas hole is d2, R is the radius of the gas hole, and ε is the dielectric constant of a vacuum. ０ The dielectric constant of the dielectric substrate is ε １ Then, the following two equations, R / ε ０ >d1 / ε １ R / ε ０ >d2 / ε １ [9] An electrostatic chuck device having the electrostatic chuck member of any one of [1] to [8].

[0007] According to one aspect of the present invention, there is provided an electrostatic chuck member and an electrostatic chuck device that can suppress large abnormal discharges and prevent plasma disturbances and damage to an object to be attracted due to heat generation.

[0008] Fig. 1 is a cross-sectional schematic view showing a preferred example of an electrostatic chuck device according to an embodiment. Fig. 2 is a schematic plan view showing a preferred example of an electrostatic chuck member according to an embodiment. Fig. 3 is a schematic view showing an example of a positional relationship between a first electrode and a second electrode of an electrostatic chuck member according to an embodiment and a gas hole. Fig. 4 is a partial cross-sectional schematic view showing a preferred example of an electrostatic chuck member according to an embodiment. Fig. 5 is a schematic view showing an example of a positional relationship between a first electrode and a second electrode of an electrostatic chuck member according to a modified example and a gas hole.

[0009] Preferred examples of each embodiment of the electrostatic chuck device of the present invention will be described below with reference to the drawings. In all of the following drawings, the dimensions and ratios of each component may be displayed differently as appropriate to make the drawings easier to understand. The following explanations are provided specifically to provide a better understanding of the gist of the invention, and do not limit the present invention unless otherwise specified. For example, unless otherwise specified, conditions such as shape, size, number, material, amount, type, position, and ratio may be changed, added, or omitted as necessary.

[0010] The Z axis is also shown in each figure. In this specification, the Z axis indicates the thickness direction of a dielectric substrate 20, which will be described later. In this specification, the Z axis extends in the vertical direction, and the direction in which the arrow of the Z axis points is the upper side, and the opposite side is the lower side, and the various parts of the electrostatic chuck device 1 will be described. Note that the vertical direction in this specification is a direction used merely for the purpose of explanation, and does not limit the orientation of the electrostatic chuck device 1 during use.

[0011] FIG. 1 is a schematic cross-sectional view showing an example of an electrostatic chuck device 1 according to this embodiment. The electrostatic chuck device 1 includes an electrostatic chuck member 2, a focus ring 4, a base 3, multiple DC power supplies 5A, 5B, and 5C, and a cooling gas supply unit 7. In FIG. 1 , the radial dimension of the focus ring 4 is drawn larger than it actually is in order to emphasize the characteristic features of the electrostatic chuck device 1 according to this embodiment. The shape and size of the focus ring 4 may be changed as desired. In this embodiment, the upper surface of the focus ring is located slightly higher than the first region on which a plate-shaped sample is placed.

[0012] The base 3 is preferably made of a metal with excellent thermal conductivity, such as an aluminum alloy. The base 3 supports the electrostatic chuck member 2 from the lower side (-Z). The base 3 is configured to adjust the electrostatic chuck member 2 to a desired temperature. The base 3 may have a flow path formed therein for circulating a low-temperature cooling medium, such as water.

[0013] A plurality of gas holes 31 are provided in the base 3. The gas holes 31 penetrate the base 3 in the thickness direction Z. The gas holes 31 are surrounded by the insulators 8 inside the base 3. The cooling gas supply unit 7 is connected to the lower end of the gas holes 31.

[0014] The cooling gas supply unit 7 supplies cooling gas to the gas holes 31. The cooling gas supply unit 7 has a pressure adjustment valve (not shown) that can adjust the pressure of the cooling gas to be supplied. As the cooling gas, for example, He gas is used.

[0015] A first electrode terminal 61, a second electrode terminal 62, a third electrode terminal 63, an insulator 8, and an insulator 9 are provided inside the base 3. The first electrode terminal 61, the second electrode terminal 62, and the third electrode terminal 63 are each rod-shaped. The first electrode terminal 61, the second electrode terminal 62, and the third electrode terminal 63 are provided to penetrate the base 3 in the thickness direction Z. The first electrode terminal 61, the second electrode terminal 62, and the third electrode terminal 63 are passed through the interior of the cylindrical insulator 9. The first electrode terminal 61, the second electrode terminal 62, and the third electrode terminal 63 are connected to DC power supplies 5A, 5B, and 5C, respectively, via high-frequency cut filters (not shown). The DC power supplies 5A, 5B, and 5C are each grounded.

[0016] The focus ring 4 is mounted on the electrostatic chuck member 2. The focus ring 4 is attracted to the electrostatic chuck member 2. The focus ring 4 is an annular member. The focus ring 4 surrounds a plate-shaped sample W mounted in the center of the electrostatic chuck member 2. The focus ring 4 is formed, for example, from a material having electrical conductivity equivalent to that of a wafer serving as the plate-shaped sample W. The focus ring 4 is controlled to be at approximately the same temperature as the plate-shaped sample W during a process such as plasma etching in a semiconductor manufacturing process. By locating the focus ring 4 on the periphery of the plate-shaped sample W, the electrical environment relative to the plasma at the periphery can be made approximately identical to that of the sample mounting surface. This prevents the etching rate on the sample mounting surface of the electrostatic chuck member 2 from becoming non-uniform between the center and periphery.

[0017] The electrostatic chuck member 2 includes a dielectric substrate 20 and electrostatic attraction electrodes 41, 42, and 43 disposed inside the dielectric substrate 20. Although not shown in FIG. 1 , in addition to the electrostatic attraction electrodes 41, 42, and 43, electrodes having other functions, such as heater electrodes for heating the dielectric substrate 20, may also be provided inside the electrostatic chuck member 2.

[0018] The dielectric substrate 20 is disk-shaped and centered on a central axis J. In the following description, the radial direction of the dielectric substrate 20 centered on the central axis J will be simply referred to as the radial direction, and the circumferential direction around the central axis J will be simply referred to as the circumferential direction.

[0019] The dielectric substrate 20 has a mounting surface 2f on which an object to be attracted is placed. The mounting surface 2f faces upward. The mounting surface 2f has a first region 2A and a second region 2B. The first region 2A is a region on which a plate-shaped sample W as an object to be attracted is placed. On the other hand, the second region 2B is a region on which a focus ring 4 as an object to be attracted is placed. The second region 2B is annular in shape surrounding the first region 2A when viewed from the thickness direction Z. The second region 2B is located below the first region 2A. In other words, the mounting surface 2f has an annular step in a region near the outer periphery.

[0020] The dielectric substrate 20 is provided with a plurality of gas holes 21, 22. The number of gas holes is selected arbitrarily. The gas holes 21, 22 penetrate the dielectric substrate 20 in the thickness direction. The lower ends of the gas holes 21, 22 in the dielectric substrate 20 are connected to the gas holes 31 in the base 3, respectively. Therefore, the gas holes 21, 22 in the dielectric substrate 20 are connected to the cooling gas supply unit 7 via the gas holes 31 in the base 3. Furthermore, the upper ends of the gas holes 21, 22 in the dielectric substrate 20 open to the mounting surface 2f. As described above, the mounting surface 2f has a first region 2A and a second region 2B. Some of the gas holes 21, 22 overlap the first region 2A when viewed in the thickness direction Z. Other of the gas holes 21, 22 overlap the second region 2B when viewed in the thickness direction Z. The cooling gas supplied to the mounting surface 2f through the gas holes 21 cools the plate-shaped sample W, which is the object to be adsorbed on the mounting surface 2f, and the focus ring 4.

[0021] The material for forming the dielectric substrate 20 can be selected arbitrarily, but ceramics having heat resistance are preferable. Examples of ceramic materials for forming the dielectric substrate 20 include aluminum oxide (Al ２ O ３ ) sintered body, aluminum nitride (AlN) sintered body, aluminum oxide (Al ２ O ３ A sintered body of silicon carbide (SiC) composite is preferably used.

[0022] The dielectric substrate 20 is formed, for example, by applying unsintered paste that forms the electrostatic attraction electrodes 41, 42, and 43 and unsintered paste for a bonding layer that bonds the ceramic plates to each other between a plurality of ceramic plates that have been formed by sintering in advance, stacking them in the thickness direction, and hot pressing them under high temperature and high pressure to integrate them.

[0023] The electrostatic attraction electrodes 41, 42, and 43 are formed in layers inside the dielectric substrate 20. The thickness of the electrostatic attraction electrodes 41, 42, and 43 can be selected arbitrarily, and is, for example, 10 μm to 50 μm. It may be 10 μm to 20 μm or 20 μm to 40 μm. The electrostatic attraction electrodes 41, 42, and 43 are a composite of an insulating material and a conductive material. The insulating material contained in the electrostatic attraction electrodes 41, 42, and 43 is not particularly limited, and may be, for example, aluminum oxide (Al ２ O ３ ), aluminum nitride (AlN), silicon nitride (Si ３ N ４ ), yttrium (III) oxide (Y ２ O ３ ), yttrium aluminum garnet (YAG) and SmAlO ３ The conductive material is preferably at least one selected from the group consisting of: ２ Examples include at least one selected from the group consisting of molybdenum (Mo), tungsten carbide (WC), tungsten (W), tantalum carbide (TaC), tantalum (Ta), silicon carbide (SiC), carbon black, carbon nanotubes, and carbon nanofibers.

[0024] Three electrostatic attraction electrodes 41, 42, and 43 are embedded in the electrostatic chuck member 2 of this embodiment. In the following description, when the three electrostatic attraction electrodes 41, 42, and 43 need to be distinguished from one another, they will be referred to as the first electrode 41, the second electrode 42, and the third electrode 43. The first electrode 41 and the second electrode 42 are located at the same position in the thickness direction Z. That is, the first electrode 41 and the second electrode 42 are arranged in the same layer within the dielectric substrate 20. On the other hand, the third electrode 43 is located above (+Z) the first electrode 41 and the second electrode 42. That is, for example, if the mounting surface in the first region 2A were extended in the horizontal direction (a direction perpendicular to the thickness direction), the thicknesswise distance from the mounting surface to the third electrode 43 in the thickness direction of the electrostatic chuck member would be shorter than the thicknesswise distance from the extended mounting surface to the first electrode 41 and the second electrode 42. The distance from the mounting surface to the first electrode 41 is equal to the distance from the mounting surface to the second electrode 42 .

[0025] FIG. 2 is a schematic plan view of the electrostatic chuck member 2 of this embodiment. As shown in FIG. 2, the first electrode 41 and the second electrode 42 are annular electrodes centered on the central axis J when viewed from the thickness direction Z. Note that in FIG. 2, the radial dimension of the second region 2B is drawn larger than actual size to emphasize the characteristic features of the electrostatic chuck device 1 of this embodiment. The first electrode 41 and the second electrode 42 of this embodiment extend circumferentially with uniform widths L1 and L2, respectively. That is, the widths of the first electrode 41 and the second electrode 42 are constant. When viewed from the thickness direction Z, the first electrode 41 is positioned radially inward relative to the second electrode 42. When viewed from the thickness direction Z, the first electrode 41 and the second electrode 42 do not overlap. In this example, the gas holes 21 and 22 are each equally spaced on one or more circles centered on the central axis J.

[0026] In this embodiment, the first electrode 41 and the second electrode 42 constitute a bipolar electrode 40. That is, the electrostatic chuck device 1 has the bipolar electrode 40 disposed inside the dielectric substrate 20. In this embodiment, a case will be described in which the first electrode 41 is positive and the second electrode 42 is negative. However, the first electrode 41 and the second electrode 42 may have different polarities, as long as one is positive and the other is negative. A DC voltage of, for example, ±2000 V to ±3000 V is applied to the first electrode 41 and the second electrode 42. Specifically, for example, a DC voltage of 2000 V to 3000 V is applied to the first electrode 41, and a DC voltage of −2000 V to −3000 V is applied to the second electrode 42. In this case, the potential difference between the first electrode 41 and the second electrode 42 is a potential difference of 4000 V to 6000 V. For example, the potential difference may be between 4500 V and 5000 V, or between 5000 V and 5500 V. Furthermore, in the present embodiment, a case will be described in which voltages of opposite polarity and equal absolute values ​​are applied to the first electrode 41 and the second electrode 42 that constitute the bipolar electrode, but the absolute values ​​of the voltages applied to the first electrode 41 and the second electrode 42 may be different from each other.

[0027] In a commonly known bipolar electrode, the width dimensions of the electrodes are substantially the same. In contrast, in the electrostatic chuck member 2 of this embodiment, the radial width dimension L1 of the first electrode 41 is larger than the width dimension L2 of the second electrode 42. It is preferable that the areas of the first electrode 41 and the second electrode 42 are the same or substantially the same as each other when viewed from the thickness direction Z.

[0028] In this embodiment, the "width dimension of the electrode" may refer to the dimension of the electrode in the direction in which the electrode extends circumferentially and in a direction perpendicular to the circumferential direction, as viewed from the thickness direction Z. The "width dimension of the electrode" may also refer to the width in the radial direction centered on the central axis J.

[0029] The first electrode 41 and the second electrode 42 overlap the second region 2B of the mounting surface 2f when viewed from the thickness direction Z. Therefore, the first electrode 41 and the second electrode 42 overlap the focus ring 4 when viewed from the thickness direction Z. The first electrode 41 and the second electrode 42 generate electric charges, which electrostatically attract the focus ring 4 to the second region 2B.

[0030] The third electrode 43 is a disk-shaped electrode. That is, the third electrode 43 is circular when viewed from the thickness direction Z. When viewed from the thickness direction Z, the third electrode 43 is located radially inward of the first electrode 41 and the second electrode 42. When viewed from the thickness direction Z, the third electrode 43 overlaps the first region 2A of the mounting surface 2f. Therefore, when viewed from the thickness direction Z, the third electrode 43 overlaps the plate-shaped sample W. The third electrode 43 generates an electric charge and electrostatically attracts the plate-shaped sample W to the first region 2A. The size of the third electrode 43 can be selected arbitrarily and may be approximately the same size as the object to be attracted, or may be smaller than the object to be attracted.

[0031] The third electrode 43 is a monopolar electrode. For example, a DC voltage of 1000 V to 2000 V is applied to the third electrode 43. In the present embodiment, the monopolar electrode (third electrode 43) is disposed in a portion overlapping the first region 2A when viewed from the thickness direction Z. However, a bipolar electrode may also be disposed in the portion overlapping the first region 2A.

[0032] 1 , a first electrode pin 51 is connected to the first electrode 41. The first electrode pin 51 extends downward from the first electrode 41. The lower end of the first electrode pin 51 is connected to a first electrode terminal 61. Therefore, the first electrode 41 is connected to the first DC power supply 5A via the first electrode pin 51 and the first electrode terminal 61.

[0033] A second electrode pin 52 is connected to the second electrode 42. The second electrode pin 52 extends downward from the second electrode 42. The lower end of the second electrode pin 52 is connected to a second electrode terminal 62. Therefore, the second electrode 42 is connected to the second DC power supply 5B via the second electrode pin 52 and the second electrode terminal 62.

[0034] A third electrode pin 53 is connected to the third electrode 43. The third electrode pin 53 extends downward from the third electrode 43. A lower end of the third electrode pin 53 is connected to a third electrode terminal 63. Therefore, the third electrode 43 is connected to a third DC power supply 5C via the third electrode pin 53 and the third electrode terminal 63.

[0035] 3 is a schematic diagram showing the positional relationship between the first electrode 41, the second electrode 42, and the gas hole 21. As shown in Fig. 3, the gas hole 21 in this embodiment is circular when viewed from the thickness direction Z. The gas hole 21 penetrates between the first electrode 41 and the second electrode 42 in the thickness direction.

[0036] In this embodiment, the gas hole 21 is positioned between the first electrode 41 and the second electrode 42, biased toward the second electrode 42. That is, the distance d1 between the first electrode 41 and the gas hole 21 is greater than the distance d2 between the second electrode 42 and the gas hole 21. In this embodiment, the outer edge of the first electrode 41 is circular and centered on the central axis J. Therefore, the distance d1 between the first electrode 41 and the gas hole 21 is the radial distance between them. Similarly, the inner edge of the second electrode 42 is circular and centered on the central axis J. Therefore, the distance d2 between the second electrode 42 and the gas hole 21 is the radial distance between them. On a line passing through the center of the dielectric substrate and the center of the gas hole 21, the sum of the distance d1, the inner diameter (diameter) of the gas hole 21, and the distance d2 may be the radial distance between the first electrode 41 and the second electrode 42. Note that the gas hole 21 does not contact the first electrode 41 or the second electrode 42.

[0037] FIG. 4 is a cross-sectional view of the gas hole 21 disposed between the first electrode 41 and the second electrode 42. FIG. 4 illustrates an electric field formed by the first electrode 41 and the second electrode 42. In the following description, the radially inner portion of the inner surface of the gas hole 21 is referred to as the first inner portion 21a, and the radially outer portion of the inner surface of the gas hole 21 is referred to as the second inner portion 21b. The first inner portion 21a is closer to the first electrode 41, and the second inner portion 21b is closer to the second electrode 42. As described above, the first electrode 41 is a positive electrode, and the second electrode is a negative electrode. Therefore, an electric field is formed inside the gas hole 21, oriented from the first electrode 41 to the second electrode 42. The electric field strength in the first inner portion 21a decreases with increasing distance above or below the first electrode 41. Similarly, the electric field strength in the second inner portion 21b decreases with increasing distance above or below the second electrode 42.

[0038] Negatively charged particles passing through the gas holes 21 are attracted to and deposited in the first inner portion 21a. Similarly, positively charged particles passing through the gas holes 21 are attracted to and deposited in the second inner portion 21b. The amount of charged particles deposited in the first inner portion 21a and the second inner portion 21b correlates with the electric field strength. The amount of negatively charged particles deposited in the first inner portion 21a decreases with increasing distance above or below the first electrode 41. Similarly, the amount of positively charged particles deposited in the second inner portion 21b decreases with increasing distance above or below the second electrode 42.

[0039] The positively charged particles and negatively charged particles are, for example, positive ion particles or negative ion particles including oxygen, nitrogen, water vapor, etc., as well as various charged particles generated by charged polymers floating in the air, sebum, aerosols, dry etching, etc. More specific examples of the composition of positive ions include H ３ O ＋ ・(H ２ O) ｎ , N.H. ４ ＋ (H ２ O) ｎ Examples of negative ion compositions include O ２ － ・(H ２ O) ｎ , CO ３ － (H ２ O) ｎ , NO ３ － (HNO ３ ) ｍ (H ２ O) ｎ The negatively charged particles deposited in the first inner portion 21 a may all be ions of the same type, but this is not necessarily the case. Similarly, the positively charged particles deposited in the second inner portion 21 b may all be ions of the same type, but this is not necessarily the case.

[0040] Charged particles deposited in the first inner portion 21a of the gas hole 21 and charged particles deposited in the second inner portion 21b repel each other. Therefore, as the amount of deposited charged particles increases, negatively charged particles and positively charged particles are ejected from the deposits in the first inner portion 21a and the second inner portion 21b, respectively. If negatively charged particles from the first inner portion 21a and positively charged particles from the second inner portion 21b are ejected simultaneously, they may accelerate while attracting each other and collide inside the gas hole 21, potentially causing a mutually attractive discharge. The first electrode 41 and the second electrode 42 in this embodiment are thin films. Therefore, the electric field strength tends to be locally increased at the same height as the electrodes 41 and 42 in the inner portions 21a and 21b of the gas hole 21, resulting in localized deposition of charged particles. Therefore, when mutual attraction discharge occurs in the electrostatic chuck member 2 of this embodiment, collisions between large charged particles with large amounts of charge may occur.

[0041] In particular, the bipolar electrode 40 of this embodiment overlaps the second region 2B as viewed in the thickness direction Z and attracts the focus ring 4. The second region 2B tends to have a smaller area than the first region 2A. Therefore, a higher voltage must be applied to the bipolar electrode 40 that overlaps the second region 2B in order to reliably attract the focus ring, which is the target area to be attracted. For example, the voltage difference between the first electrode 41 and the second electrode 42 of this embodiment is, for example, 4000 V or more. Therefore, in the gas hole 21 that opens into the second region 2B, the electric field strength of the first inner portion 21a and the second inner portion 21b is likely to be high, and collisions of charged particles with large electric charges are likely to occur.

[0042] According to the electrostatic chuck member 2 of this embodiment, the distance d1 from the first inner portion 21a to the first electrode 41 is greater than the distance d2 from the second inner portion 21b to the second electrode 42. Therefore, the electric field strength in the first inner portion 21a is likely to be smaller than the electric field strength in the second inner portion 21b. As a result, the amount of negatively charged particles deposited in the first inner portion 21a is smaller than the amount of positively charged particles deposited in the second inner portion 21b. Furthermore, the electric field strength distribution in the first inner portion 21a is lower in the center and wider at the base than the electric field strength distribution in the second inner portion 21b. Accordingly, the distribution of negatively charged particles deposited in the first inner portion 21a is lower in the center and wider at the base than the distribution of positively charged particles deposited in the second inner portion 21b. That is, the distribution of accumulated charged particles differs between the first inner portion 21a and the second inner portion 21b.

[0043] Therefore, the amount of negatively charged particles accumulated in the first inner portion 21 a can be reduced, and the amount of charged particles escaping from the first inner portion 21 a can be reduced. As a result, even if positively charged particles are escaping from the second inner portion 21 b, collisions with negatively charged particles are unlikely to occur, and the occurrence of mutually attracted discharge can be reduced.

[0044] In this embodiment, the distribution of accumulated charged particles differs between the first inner portion 21 a and the second inner portion 21 b. Therefore, even when charged particles are emitted from each of the first inner portion 21 a and the second inner portion 21 b, positively charged particles and negatively charged particles are unlikely to be emitted simultaneously. As a result, collisions between positively charged particles and negatively charged particles are unlikely to occur, and mutually attracted discharges can be suppressed.

[0045] In this embodiment, the distance between the first electrode 41 and the gas holes 21 is d1, and the distance between the second electrode 42 and the gas holes is d2. Furthermore, the value represented by α in the following equation is defined as the gas hole position asymmetry ratio: α = (d1 - d2) / (d1 + d2) In this embodiment, the gas hole position asymmetry ratio α preferably satisfies the following: 0 < α ≦ 0.95 In this embodiment, d1 is greater than d2, and therefore α is always greater than 0.

[0046] By setting the gas hole position asymmetry rate α to a value greater than 0, the deposition amount and deposition distribution of charged particles deposited in the first inner portion 21a and the second inner portion 21b can be made different, thereby suppressing the occurrence of mutual attraction discharge. Furthermore, while the effect of suppressing mutual attraction discharge can be enhanced by setting the gas hole position asymmetry rate α too close to 1, the distance d2 between the gas hole 21 and the second electrode 42 becomes too small, which may result in dielectric breakdown near the second inner portion 21b. In other words, it is undesirable for the gas hole 21 to be too close to the second electrode 42. For this reason, the gas hole position asymmetry rate α is preferably 0.95 or less. For the same reason, the gas hole position asymmetry rate α is more preferably 0.03 to 0.70, even more preferably 0.05 to 0.5, and even more preferably 0.1 to 0.3. The gas hole position asymmetry rate α may be 0.01 or more and 0.80 or less, 0.15 or more and 0.60 or less, or 0.2 or more and 0.4 or less, as necessary. The gas hole position asymmetry rate α is 0 when the distance d1 between the first electrode 41 and the gas hole 21 and the distance d2 between the second electrode 42 and the gas hole 21 are equal to each other.

[0047] The distance d1 between the first electrode 41 and the gas hole 21 and the distance d2 between the second electrode 42 and the gas hole 21 can be selected arbitrarily, but are preferably set in the range of 0.5 mm to 5 mm. Setting these distances d1 and d2 to 0.5 mm or greater ensures sufficient distance between the first electrode 41 and the second electrode 42 and the gas hole 21, thereby preventing dielectric breakdown. Setting these distances d1 and d2 to 5 mm or less allows the bipolar electrode 40 to attract the focus ring 4 from the inside and outside in the radial direction in a balanced manner. The distances d1 and d2 may each be set to 0.8 mm to 4.5 mm, 1.0 mm to 4.0 mm, 1.5 mm to 3.5 mm, or 2.0 mm to 2.5 mm, for example.

[0048] In this embodiment, the width L1 of the first electrode 41 is larger than the width L2 of the second electrode 42. Therefore, the electric field in the first inner portion 21a is much smaller than that in the second inner portion 21b. As a result, the amount of negatively charged particles deposited in the first inner portion 21a is much smaller than the amount of positively charged particles deposited in the second inner portion 21b. Furthermore, the electric field strength distributions in the first inner portion 21a and the second inner portion 21b are different from each other. As a result, the distribution of negatively charged particles deposited in the first inner portion 21a is different from the distribution of positively charged particles deposited in the second inner portion 21b. Therefore, according to this embodiment, the effect of suppressing mutually attracted discharges due to the difference in the distances d1, d2 between the gas hole 21 and the first electrode 41 and the second electrode 42 can be further enhanced.

[0049] In this embodiment, the width dimension of the first electrode 41 is L1, and the width dimension of the second electrode 42 is L2. Furthermore, the value represented by β in the following equation is defined as the bipolar electrode asymmetry rate: β = (L1 - L2) / (L1 + L2) In this embodiment, the bipolar electrode asymmetry rate β preferably satisfies the following: 0 < β ≦ 0.95. In this embodiment, L1 is greater than L2, so β ​​is always greater than 0.

[0050] By setting the bipolar electrode asymmetry ratio β to a value greater than 0, the amount and distribution of charged particles deposited on the first inner portion 21a and the second inner portion 21b can be made different, thereby suppressing the occurrence of mutually attractive discharge. Furthermore, if the bipolar electrode asymmetry ratio β is set too close to 1, the area ratio of the second electrode 42 to the area of ​​the first electrode 41 may become too small, which may result in a decrease in the electrostatic attraction force of the bipolar electrode 40. For this reason, the bipolar electrode asymmetry ratio β is preferably 0.95 or less. For the same reasons, the bipolar electrode asymmetry ratio β is more preferably 0.03 to 0.70, even more preferably 0.05 to 0.5, and even more preferably 0.1 to 0.3. The bipolar electrode asymmetry ratio β may be 0.01 to 0.80 or 0.2 to 0.4, as needed. The bipolar electrode asymmetry rate β is 0 when the width dimension L1 of the first electrode 41 and the width dimension L2 of the second electrode 42 are equal to each other.

[0051] The widths L1 and L2 of the first electrode 41 and the second electrode 42 are preferably in the range of 5 mm to 20 mm. The widths L1 and L2 may be in the range of 7 mm to 18 mm, 10 mm to 16 mm, or 12 mm to 14 mm. Setting the widths L1 and L2 of the first electrode 41 and the second electrode 42 to 5 mm or greater allows the first electrode 41 and the second electrode 42 to attract the focus ring 4 over a wide area, thereby increasing the attraction force of the electrostatic chuck member 2. Setting the widths L1 and L2 of the first electrode 41 and the second electrode 42 to 20 mm or less prevents the electrostatic chuck member 2 from becoming too large. The thicknesses of the first electrode 41 and the second electrode 42 can be selected arbitrarily, but may be the same.

[0052] In this embodiment, it is preferable that the gas hole position asymmetry rate α and the bipolar electrode asymmetry rate β satisfy the relationship α>β.

[0053] The mutual attraction discharge in the electrostatic chuck member 2 of this embodiment is more effectively suppressed by the combined effect of the effect of setting the gas hole position asymmetry rate α to a value greater than 0 and the suppression effect of setting the bipolar electrode asymmetry rate β to a value greater than 0. Here, in this embodiment, the suppression effect of increasing the gas hole position asymmetry rate α is greater than the suppression effect of increasing the bipolar electrode asymmetry rate β. Therefore, by setting the gas hole position asymmetry rate α to be greater than the bipolar electrode asymmetry rate β, the mutual attraction discharge in the gas holes 21 can be more effectively suppressed.

[0054] In this embodiment, when the radius of the gas hole 21 is R, it is preferable to satisfy the following formula: (d1-d2)>R. It is more preferable to satisfy the following formula: (d1-d2)>2R.

[0055] In the electrostatic chuck member 2 of this embodiment, the asymmetry of the arrangement of the gas holes 21, ie, the difference (d1-d2) between the distance d1 between the first electrode 41 and the gas holes 21 and the distance d2 between the second electrode 42 and the gas holes 21, is greater relative to the radius R of the gas holes 21. This makes it easier to increase the asymmetry of the electric field intensity distribution, thereby enhancing the effect of suppressing mutual attraction discharge. For the same reason, it is more preferable that the difference (d1-d2) be greater than the diameter 2R of the gas holes 21 (i.e., (d1-d2)>2R).

[0056] In this embodiment, the dielectric constant of a vacuum is ε ０ and the dielectric constant of the dielectric substrate is ε １ Then, the following two equations are obtained: R / ε ０ >d1 / ε １ R / ε ０ >d2 / ε １ It is preferable to simultaneously satisfy the above.

[0057] By making the electric field strength inside the gas hole 21 smaller than the electric field strength inside the dielectric substrate 20, the electric field inside the gas hole 21 is more likely to disperse rather than concentrate. Here, the electric field strength is expressed as electric flux density / dielectric constant. That is, the electric field strength is inversely proportional to the dielectric constant. Therefore, by satisfying the above two formulas, the distribution of the electric field strength in the first inner portion 21a and the second inner portion 21b is more likely to spread, and the electric field strength in the first inner portion 21a and the second inner portion 21b is less likely to become locally high. As a result, it is possible to suppress both the accumulation of negatively charged particles in the first inner portion 21a and the accumulation of positively charged particles in the second inner portion 21b, and as a result, it is possible to suppress mutually attracted discharge. The electric field strength may represent the number of electric field lines per unit area, and the electric flux density may represent the amount of electric flux passing through per unit area, or may be expressed as a proportional constant between the electric flux density and the electric field. The dielectric constant of a vacuum, ε ０ For example, 8.854 × 10 －１２ The dielectric constant ε1 of the dielectric substrate depends on the material of the substrate and the type and amount of additives, but is, for example, 8 to 15 × 10 －１２ [F / m] or several tens to several hundreds x 10 －１２ [F / m], but is not limited to these.

[0058] According to this embodiment, the first electrode 41 is located radially inward relative to the gas hole 21, and the second electrode 42 is located radially outward relative to the gas hole 21. According to this embodiment, the gas hole 21 can be disposed radially outward in the region between the first electrode 41 and the second electrode 42. Therefore, when a mutually attractive discharge occurs inside the gas hole 21, the position where the mutually attractive discharge occurs can be separated from the central axis J of the dielectric substrate 20. As a result, it is easier to suppress the influence of plasma disturbance caused by the occurrence of the mutually attractive discharge on processing steps such as plasma etching. Furthermore, the occurrence of the mutually attractive discharge is less likely to damage the plate-shaped sample W placed on the placement surface 2f.

[0059] In the electrostatic chuck member 2 of this embodiment, the third electrode 43 disposed directly below the first region 2A that attracts the plate-shaped sample W is a monopolar electrode. Therefore, mutual attraction discharge does not occur inside the gas hole 22 that opens into the first region 2A. However, if a bipolar electrode is disposed directly below the first region 2A, the same problem (occurrence of mutual attraction discharge) as that directly below the second region 2B may occur inside the gas hole 22. In this case, the occurrence of mutual attraction discharge can be suppressed by satisfying a relationship similar to the relationship between the bipolar electrode 40 (first electrode 41 and second electrode 42) and the gas hole 21 described above.

[0060] 5 is a schematic diagram showing a positional relationship between the first electrode 141 and the second electrode 142 and the gas holes 21 in a modified example that can be used in the above-described embodiment. Note that the same components as those in the above-described embodiment are denoted by the same reference numerals, and their description will be omitted.

[0061] Similar to the above-described embodiment, the electrostatic chuck member 102 of this modification includes a dielectric substrate 20 and a bipolar electrode 140 disposed inside the dielectric substrate 20. The bipolar electrode 140 also includes a first electrode 141 and a second electrode 142 extending in the circumferential direction and aligned in the radial direction. The dielectric substrate 20 is further provided with gas holes 21 that penetrate between the first electrode 141 and the second electrode 142. The first electrode 141 is located radially inward of the gas holes 21. The second electrode is located radially outward of the gas holes.

[0062] In this modification, a curved portion 142p that conforms to the shape of the gas hole 21 is provided on the radially inner edge of the second electrode 142. The curved portion 142p has an arc shape centered on the gas hole 21. The curved portion 142p has a shape that protrudes outward in a plan view. According to this modification, the arc-shaped curved portion 142p is provided on the edge of the second electrode 142 facing the gas hole 21, thereby preventing the distance between the second electrode 142 and the gas hole 21 from becoming locally close, thereby suppressing dielectric breakdown. Note that, in this modification, a case has been described in which the curved portion 142p is provided only on the second electrode 142, but a similar curved portion may also be provided on the radially outer edge of the first electrode 141. When a curved portion is provided on the radially outer edge of the first electrode 141, the curved portion has a shape that protrudes inward in a plan view.

[0063] According to the electrostatic chuck member 102 of this modified example, similarly to the above-described embodiment, the distance d11 between the first electrode 141 and the gas hole 21 is larger than the distance d12 between the second electrode 142 and the gas hole 21, and the width dimension L11 of the first electrode 141 is larger than the width dimension L12 of the second electrode 142. Therefore, similarly to the above-described embodiment, the electrostatic chuck member 102 of this modified example can also suppress the occurrence of mutual induction discharge inside the gas hole 21.

[0064] In this specification, the distances d11 and d12 between the first electrode 141 and the second electrode 142 and the gas hole 21 are distances that affect the electric field strength in the first inner portion 21a and the second inner portion 21b of the gas hole 21. Therefore, these distances d11 and d12 are the shortest distances between the first electrode 141 or the second electrode 142 and the gas hole 21 when viewed from the thickness direction Z, and are distances in the radial direction in this modified example.

[0065] In addition, in this specification, the width dimensions L11 and L12 of the first electrode 141 and the second electrode 142 are distances that affect the electric field strength at the first inner portion 21 a and the second inner portion 21 b of the gas hole 21. Therefore, these width dimensions L11 and L12 are the smallest width dimensions L11 and L12 at the portions closest to the gas hole 21 in the direction in which the first electrode 141 and the second electrode 142 extend, respectively, and are width dimensions in the radial direction in this embodiment.

[0066] While the embodiments and modifications of the present invention have been described above, the configurations and combinations thereof in the embodiments and modifications are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited to the embodiments.

[0067] For example, in the above-described embodiment and its modified examples, the gas holes may not be completely hollow but may be partially filled with a porous material. Furthermore, the gas holes are not limited to being linear, and may extend, for example, in a spiral shape.

[0068] DESCRIPTION OF SYMBOLS 1 Electrostatic chuck device 2, 102 Electrostatic chuck member 2f Mounting surface 2A First region 2B Second region 3 Base 4 Focus ring 5A First DC power supply 5B Second DC power supply 5C Third DC power supply 7 Cooling gas supply unit 8 Insulator surrounding gas hole 9 Insulator surrounding electrode terminal 20 Dielectric substrate 21, 22, 31 Gas hole 21a First inner portion 21b Second inner portion 31 Gas hole of base 40, 140 Bipolar electrode 41, 141 First electrode 42, 142 Second electrode 43 Third electrode 43 51 First electrode pin 52 Second electrode pin 53 Third electrode pin 61 First electrode terminal 62 Second electrode terminal 63 Third electrode terminal R Radius d1, d2, d11, d12 Distance J: central axis of dielectric substrate L1, L2, L11, L12: width dimension R: radius, W: plate-shaped sample (object to be adsorbed), Z: thickness direction

Claims

1. An electrostatic chuck member comprising: a disk-shaped dielectric substrate having a mounting surface on which at least one object to be attracted is placed; and a bipolar electrode disposed inside the dielectric substrate and electrostatically attracting the object to be attracted to the mounting surface, wherein the bipolar electrode includes a first electrode and a second electrode having opposite polarities; the dielectric substrate is provided with a gas hole penetrating between the first electrode and the second electrode in the thickness direction of the dielectric substrate; the distance between the first electrode and the gas hole is greater than the distance between the second electrode and the gas hole; and the width dimension of the first electrode is greater than the width dimension of the second electrode.

2. An electrostatic chuck member comprising: a disk-shaped dielectric substrate having a mounting surface on which at least one object to be attracted is placed; and a bipolar electrode disposed inside the dielectric substrate and electrostatically attracting the object to be attracted to the mounting surface, wherein the bipolar electrode includes a first electrode and a second electrode having opposite polarities; the dielectric substrate is provided with a gas hole penetrating between the first electrode and the second electrode in the thickness direction of the dielectric substrate; the distance between the first electrode and the gas hole is greater than the distance between the second electrode and the gas hole; the first electrode is located radially inward of the dielectric substrate with respect to the gas hole; and the second electrode is located radially outward of the gas hole.

3. An electrostatic chuck member according to claim 1 or 2, wherein the object to be attracted includes a plate-like sample and a focus ring, the mounting surface has a first region on which the plate-like sample as the object to be attracted is placed, and a second region which is annular and surrounds the first region when viewed in the thickness direction of the dielectric substrate, and on which the focus ring as the object to be attracted is placed, and the bipolar electrode overlaps the second region when viewed in the thickness direction.

4. The electrostatic chuck member according to claim 1 or 2, wherein, when the distance between the first electrode and the gas hole is d1 and the distance between the second electrode and the gas hole is d2, the value represented by α in the following equation is the gas hole position asymmetry rate, α = (d1 - d2) / (d1 + d2), and the gas hole position asymmetry rate satisfies 0 < α ≦ 0.

95.

5. The electrostatic chuck member according to claim 1, wherein, when the width dimension of the first electrode is L1 and the width dimension of the second electrode is L2, the bipolar electrode asymmetry rate is defined as the value represented by β in the following equation: β=(L1-L2) / (L1+L2), wherein the bipolar electrode asymmetry rate satisfies 0<β≦0.

95.

6. The electrostatic chuck member according to claim 1, wherein, when the distance between the first electrode and the gas hole is d1 and the distance between the second electrode and the gas hole is d2, the value represented by α in the following equation is the gas hole position asymmetry rate: α = (d1 - d2) / (d1 + d2) When the width dimension of the first electrode is L1 and the width dimension of the second electrode is L2, the value represented by β in the following equation is the bipolar electrode asymmetry rate: β = (L1 - L2) / (L1 + L2) The gas hole position asymmetry rate and the bipolar electrode asymmetry rate satisfy the following equation: α > β.

7. An electrostatic chuck member according to claim 1 or 2, wherein the following equation is satisfied: (d1 - d2) > R, where d1 is the distance between the first electrode and the gas hole, d2 is the distance between the second electrode and the gas hole, and R is the radius of the gas hole.

8. The distance between the first electrode and the gas hole is d1, the distance between the second electrode and the gas hole is d2, the radius of the gas hole is R, and the dielectric constant of vacuum is ε ０ The dielectric constant of the dielectric substrate is ε １ Then, the following two equations, R / ε ０ >d1 / ε １ R / ε ０ >d2 / ε １ The electrostatic chuck member according to claim 1 or 2, wherein the above conditions are met simultaneously.

9. An electrostatic chuck device comprising the electrostatic chuck member of claim 1 or 2.

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