JP6595406B2 - Electrostatic adsorption member - Google Patents

Description

  The present disclosure relates to an electrostatic adsorption member.

  Conventionally, in the manufacturing process of a semiconductor integrated circuit and the manufacturing process of a liquid crystal display device, an electrostatic chuck member such as an electrostatic chuck is used as a component for holding each sample such as a semiconductor wafer.

  In such an electrostatic chucking member, an electrode layer for electrostatic chucking is provided inside a dielectric member made of, for example, ceramic. In such an electrostatic chucking member, a power supply terminal for applying an electrostatic chucking voltage to the electrode layer is continuously arranged from the outside of the dielectric member to the internal electrode layer. For example, in Patent Document 1, an electrode layer parallel to the adsorption surface is provided inside a substrate having an adsorption surface on which an object is adsorbed, and penetrates the substrate from the surface opposite to the adsorption surface to the electrode layer. A columnar power supply terminal is inserted into the through-hole. In Patent Document 1, the power supply terminal is mechanically fixed in the through hole in a state where the end of the power supply terminal is in contact with the electrode layer.

JP 2004-311522 A

  In the electrostatic chuck proposed in Patent Document 1, since the power supply terminal expands and contracts as the temperature rises and cools, the electrode layer in contact with the end of the power supply terminal is pressed or stretched reversely by the expansion and contraction of the power supply terminal. There was a case. For this reason, conventionally, there has been a problem that the electrode layer is broken or broken due to the pressing or pulling.

In order to solve the above problem, the present application is made of ceramics , has a suction surface on which an object is sucked , and has a base having a recess opened on a surface other than the suction surface, and a direction perpendicular to the suction surface is increased. The inner electrode positioned at a position lower than the suction surface of the substrate and higher than the recess, a conductive layer connected to the internal electrode from the recess, and the recess, A member for electrostatic attraction comprising a power feeding terminal connected to the conductive layer , wherein the bottom surface of the concave portion is open, and an opening area in the bottom surface is smaller than an area of an end surface of the power feeding terminal; There is provided a member for electrostatic attraction having a hollow region extending from the inside to the internal electrode .

  The electrostatic attraction member of this embodiment can suppress damage to the internal electrode.

An example of the vacuum chuck which is the member for electrostatic attraction of this embodiment is shown, (a) is a perspective view, (b) is a plane perspective view. FIGS. 1A and 1B are cross-sectional views showing an example of a cross section taken along line AA ′ of the vacuum chuck shown in FIG. 1, and FIG. 2B is an enlarged cross-sectional view of a part of the internal electrode shown in FIG. 1A and 1B show another example of a cross section taken along line AA ′ of the vacuum chuck shown in FIG. 1, and FIG. 4B is an enlarged cross sectional view of a part of the internal electrode shown in FIG. It is sectional drawing which shows the other example of the cross section in the AA 'line of the vacuum chuck shown in FIG. 1, (b) is sectional drawing to which some internal electrodes shown to (a) were expanded, (c) is ( It is sectional drawing to which a part of electrically conductive layer shown to a) was expanded, (d) is sectional drawing to which the B section shown to (a) was expanded.

  Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. However, in all the drawings in this specification, the same parts are denoted by the same reference symbols unless the confusion occurs, and the description thereof is omitted as appropriate.

  1 and 2 show an example of a vacuum chuck that is a member for electrostatic attraction according to the present embodiment. FIG. 1 (a) is a perspective view, and FIG. 1 (b) is a plan perspective view. 2 shows an example of a cross section taken along line AA ′ of the vacuum chuck shown in FIG. 1, (a) is a cross-sectional view, and (b) is an enlarged cross section of a part of the internal electrode shown in (a). FIG.

  The electrostatic attraction member shown in FIGS. 1 and 2 is made of ceramics, and has a suction surface 1a on which an object (not shown) is attracted and a base (1,2) having a recess 2a opened on a surface other than the suction surface 1a. And an internal electrode 3 positioned between the suction surface 1a and the recess 2a of the base (1, 2), and a conductive layer 4 connected to the internal electrode 3 from the recess 2a. A hollow region 2b is provided between 2a and the internal electrode 3.

The bases (1, 2) are a first structure 1 made of ceramics having an adsorption surface 1a on which an object (not shown) is adsorbed, and a second structure made of ceramics provided on the opposite side of the adsorption surface 1a. 2, and the internal electrode 3 is disposed between the first structure 1 and the second structure 2. The internal electrode 3 is composed of a pair of separated internal electrodes 3a and 3b, one of which is connected to the positive electrode of a power source (not shown) via a power supply terminal 5a, and the other is connected to the negative electrode of the power supply via a power supply terminal 5b. Connected. For example, the electrode on the side connected to the positive electrode of the power source is an internal electrode 3a (hereinafter referred to as internal electrode 3a).
a is referred to as a positive electrode 3a. The electrode on the side connected to the negative electrode is the internal electrode 3b (hereinafter, the internal electrode 3b is referred to as the negative electrode 3b). Conversely, the internal electrode 3a may be connected to the negative electrode, and the internal electrode 3b may be connected to the positive electrode.

  The positive electrode 3a and the negative electrode 3b are each formed in a semicircular shape, and are arranged so that the semicircular chords face each other. By arranging the positive electrode 3a and the negative electrode 3b in this way, the entire outer shape of the internal electrode 3 becomes circular. The center of the entire internal electrode 3 coincides with the center of the first structure 1 or is located near the center of the first structure 1. The internal electrode 3 is formed on the upper surface of the second structure 2 and is bonded to the lower surface of the first structure 1 via a bonding layer 6 made of resin.

  The member for electrostatic attraction 10 has a hollow region 2 b between the recess 2 a and the internal electrode 3. Thereby, even when the power supply terminals 5a and 5b are thermally expanded, the end portions of the power supply terminals 5a and 5b are not in contact with the positive electrodes 3a and 3b. Since the deformation of the structure 2 remains, breakage such as cracks and chips in the internal electrode 3 is suppressed.

  More specifically, the electrostatic attraction member 10 is such that the second structure 2 has a columnar recess 2a that is recessed from the surface opposite to the internal electrode 3 toward the internal electrode 3, and the internal electrode of the recess 2a. 3 is provided with a through hole penetrating from the end face on the side 3 to the internal electrode 3, and the internal space of the through hole is a hollow region 2b. The conductive layer 4 is continuously deposited on the inner side surface of the columnar recess 2a and the inner side surface of the hollow region (through hole 2b), and is electrically connected to the internal electrode 3. The shapes of the recess 2a and the hollow region 2b are, for example, cylindrical. The conductive layer 4 may be a plate having a thickness of, for example, 0.55 μm or more and 0.85 μm or less, or may be a cylindrical conductor.

In the electrostatic attraction member 10 shown in FIG. 2 and 10a and 10b shown in FIGS. 3 and 4 to be described later, the internal electrode 3 includes a first electrode layer 3A mainly composed of titanium, titanium nitride, and titanium carbide. Or the second electrode layer 3B mainly composed of titanium carbonitride, the second electrode layer 3B is located on the first electrode layer 3A, and the first electrode layer 3A is joined to the second structure 2 It is preferable that With such a configuration, titanium forming the first electrode layer 3A has high activity and exhibits good wettability with respect to the ceramic forming the second structure 2, so the second electrode layer 3B The adhesion strength to the second structure 2 is high.

  FIG. 3 is a cross-sectional view showing another example of a cross section taken along the line AA ′ of the vacuum chuck shown in FIG. 1, and FIG. 3B is a cross-sectional view in which a part of the internal electrode shown in FIG.

  In the electrostatic attraction member 10a shown in FIG. 3, the conductive layer 4 in the recess 2a has a threaded portion 4a. In this case, since the surface area of the conductive layer 4 is relatively large and the area of electrical connection with the side surface of the power supply terminal 5b is large, relatively stable power supply can be performed. Further, by using the power supply terminal 5b provided with the screw thread portion 4a on the side surface, the power supply terminal 5b is engaged with the screw thread portion 4a and the power supply terminal 5b is firmly fastened to the second structure 2. be able to. In addition, since the power supply terminal 5b can be easily and repeatedly detached by fastening with screws, maintenance work such as cleaning of the power supply terminal 5b can be performed relatively easily over a long period of time.

  4 is a cross-sectional view showing another example of the cross section taken along the line AA ′ of the vacuum chuck shown in FIG. 1, and FIG. 4B is a cross-sectional view in which a part of the internal electrode shown in FIG. (c) is sectional drawing to which a part of conductive layer shown to (a) was expanded, (d) is sectional drawing to which the B section shown to (a) was expanded.

  The electrostatic attraction member 10b shown in FIG. 4 includes a spiral conductive wire 7 that contacts the inner peripheral surface of the conductive layer 4 in the recess 2a. The conductive layer 4 inside the recess 2a is relatively difficult to replace and requires a lot of work. However, when the conductive layer 4 is provided with a spiral conductive wire 7, for example, the conductive wire 7 can be removed by repeatedly attaching and detaching the power supply terminals 5a and 5b. Even if it wears out, the state (shape, corrosion condition, etc.) of the portion in contact with the power supply terminals 5a and 5b can be refreshed by simply replacing the conductive wire 7.

  Here, the spiral conductive wire 7 is, for example, Helisart (registered trademark, manufactured by Tsugami Co., Ltd.), E-Sert (registered trademark, manufactured by Tsugami Co., Ltd.), Irisert (registered trademark, (existing) wide) Sugi Seiki).

  The spiral conductive wire 7 is made of, for example, 18-8 stainless steel. However, if it is difficult to be affected by magnetism, a material made of phosphor bronze may be used.

  Moreover, the member 10b for electrostatic attraction is suitable in that the conductive wire 7 is not easily detached from the recess 2a when the conductive wire 7 is fixed via the bonding agent 8. In particular, the bonding agent 8 is preferably conductive. The region including the bonding agent 8 is, for example, a region within h / 2 from the upper end of the conductive wire 7 with respect to the height h of the conductive wire 7.

  In the electrostatic attraction member 10b shown in FIG. 4, as shown in FIG. 4 (b), the conductive layer 4 includes the first layer 4A mainly composed of titanium, titanium nitride, titanium carbide, or titanium carbonitride. And the second layer 4B is located on the first layer 4A, and the first layer 4A is bonded to the base body (second structure 2) made of ceramics. Is preferred. With such a configuration, titanium forming the first layer 4A has high activity and exhibits good wettability with respect to the ceramic forming the second structure 2, and therefore the first layer 4A is formed of the base ( The adhesion strength to the second structure 2) is increased. For example, the thickness of the first layer 4A is 0.15 μm or more and 0.25 μm or less, and the thickness of the second layer 4B is 0.4 μm or more and 0.6 μm or less.

  Also, in the electrostatic attraction member 10b shown in FIG. 4, it is preferable that the inner peripheral surface of the conductive wire 7 is exposed.

  The state in which the inner peripheral surface is exposed refers to a state in which the bonding agent 8 or the like is not attached to the inner peripheral surface. By making such a state, the particle caused by the bonding agent 8 Occurrence can be suppressed.

  The main component in the first layer 4A, the second layer 4B, the first electrode layer 3A, and the second electrode layer 3B is a component that occupies 95% or more of the total 100% by mass of the components constituting each layer. Inevitable impurities may be included as components other than the main component. The components constituting each of these layers are identified by a thin film X-ray diffraction method, and the content of each component may be obtained by a Rietveld method.

  2, 3, and 4, when the arithmetic average roughness Ra of the suction surface 1 a is 0.85 μm or less (excluding 0 μm), the suction surface. Since the unevenness | corrugation in 1a becomes small, the attraction | suction force with respect to a target object can be improved. The arithmetic average roughness Ra of the suction surface 1a is 0.4 μm or less, and more preferably 0.2 μm or less.

  The arithmetic average roughness Ra may be measured in accordance with JIS B 0601-2013. The measurement length and the cut-off value are 5 mm and 0.8 mm, respectively, and are measured using a stylus type surface roughness meter. If this is the case, for example, a stylus having a stylus tip radius of 2 μm is applied to the suction surface 1a, and the scanning speed of the stylus is set to 0.5 mm / second. The value may be the value of the arithmetic average roughness Ra.

  In addition, in the electrostatic chucking members 10, 10a, and 10b shown in FIGS. 2, 3, and 4, the base body (first structure 1, second structure 2) includes the first structure 1 having the suction surface 1a; It is preferable that the ceramic forming the first structure 1 including the second structure 2 in which the recess 2 a is located has a higher dielectric breakdown strength than the ceramic forming the second structure 2.

  With such a configuration, the object is adsorbed to the adsorption surface 1a by a Coulomb force having an adsorption force smaller than the Johnson Rabeck force, which is effective for an electrostatic adsorption member that requires high desorption response. .

  For example, the dielectric breakdown strength of the ceramics forming the first structure 1 is 14 KV / mm or more and 15 KV / mm or less, and the dielectric breakdown strength of the ceramics forming the second structure 1 is more than 15 KV / mm. Large, 50 KV / mm or less. In particular, the ceramic forming the first structure 1 is mainly composed of polycrystalline aluminum oxide, and is, for example, a ceramic containing a sintering aid such as magnesium oxide, calcium oxide, or silicon oxide. The ceramic forming the second structure 3 is preferably a ceramic mainly composed of polycrystalline aluminum oxide and not containing the sintering aid, or a ceramic mainly composed of single crystal aluminum oxide (sapphire). It is. The dielectric breakdown strength of each ceramic may be determined in accordance with JIS C 2141-1992.

  In addition, in the electrostatic attraction members 10, 10 a, and 10 b shown in FIGS. 2, 3, and 4, the ceramic forming the first structure 1 is at least a part of the surface layer portion including the attraction surface 1 a. Is preferably conductive or semiconductive. In the case of such a configuration, when the object is adsorbed on the adsorption surface 1a by the Johnson Rabeck force, it is preferable in that the adsorption force can be made relatively high.

In this embodiment, the term “conductive” refers to a volume resistivity of less than 10 ⁻² Ω · cm, and the term “semiconductive” refers to a range in which the volume resistivity is 10 ⁻² Ω · cm or more and less than 10 ¹³ Ω · cm. Say.

  Here, the ceramic forming the first structure 1 includes, for example, polycrystalline aluminum oxide as a main component, and includes at least one of titanium and niobium as a metal element, and the content of the metal element in the surface layer portion However, there is more content of the said metallic element in an inside.

In addition, when the ceramics which form the 1st structure 1 are the said ceramics, content of the alumina and the metal element in the whole ceramics, surface layer part, inside is an ICP (Inductively Coupled Plasma) emission spectroscopic analyzer or fluorescent X-rays Using an analyzer, the contents of Al, Ti, and Nb are obtained. For alumina, Al is converted to Al ₂ O ₃ , and Ti and Nb may be obtained with the obtained measured values as they are. In addition, when calculating | requiring content in the whole ceramics, what is necessary is just to use the sample which grind | pulverized the sintered compact including a surface layer part and the inside uniformly, and if it is a surface layer part and the inside, it will sample from the area | region corresponding to a surface layer part and an inside. A sample obtained by collecting and pulverizing can be used.

  Next, an example of a method for manufacturing the electrostatic attraction member of the present embodiment will be described.

  First, ceramic members corresponding to the first structure 1 and the second structure 2 are prepared. In the second structure 2, a concave portion 2 having a predetermined shape is formed on one main surface, and a through hole corresponding to the hollow region 2b is formed between the concave portion 2 and the other main surface. You may form a thread part in the inner surface of the recessed part 2 as needed.

  The internal electrode 3 and the conductive layer 4 are formed by forming a metal film on the second structure 2 by, for example, an ion plating method. For example, the first electrode layer 3A mainly composed of titanium and titanium nitride, titanium carbide, or carbonitride with one main surface of the second structure 2 masked on a portion other than the internal electrode 3 After forming the second electrode layer 3B mainly composed of titanium, the masking is removed. Further, from the surface of the second structure 2 on the side where the concave portion 2 is provided, the first layer 4A containing titanium as a main component and titanium nitride, titanium carbide, or titanium carbonitride as the main components by ion plating. The second layer 4B is formed.

  Alternatively, the internal electrode 3 and the conductive layer 4 may be formed simultaneously by forming a metal film by an ion plating method while rotating the second ceramic structure 2. At this time, for example, the second structure 2 masked in a predetermined region is rotated while a radial straight line at the half position of the thickness of the second structure 2 is used as an axis, that is, an ion plating method. The metal film may be formed while rotating the second structure so that the two main surfaces of the second structure alternately face the target metal. In this case, the first electrode layer 3A and the first layer 4A are simultaneously formed as a metal film mainly composed of titanium, and the second electrode is formed as a metal film mainly composed of titanium nitride, titanium carbide, or titanium carbonitride. The layer 3B and the second layer 4B can be formed simultaneously.

  Thereafter, an epoxy adhesive is applied to the other main surface of the second structure 2. Then, the first structure 1 and the second structure 2 are joined to each other by pressing the first structure 1 on the other main surface of the second structure 2 so as to face each other. obtain. Then, the member for electrostatic attraction of this embodiment can be obtained by grinding the surface of the joined body.

Here, in order to obtain a member for electrostatic adsorption having an arithmetic average roughness Ra of the adsorption surface of 0.85 μm or less (excluding 0 μm), for example, polishing with diamond abrasive grains having an average particle diameter of 3 μm or less. Can be obtained.

  The present invention is not limited to the above-described embodiments, and various modifications, improvements, combinations, and the like can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 1st structure 1a Adsorption surface 2 2nd structure 2a Recessed part 2b Internal area 3 Internal electrode 3A 1st electrode layer 3B 2nd electrode layer 4 Conductive layer 4a Thread part 4A 1st layer 4B 2nd layer 5a, 5b Terminal 6 Bonding layer 7 Conductive wire 8 Bonding agent

Claims (8)

A substrate made of ceramics , having a suction surface on which an object is adsorbed , and having a recess opened on a surface other than the adsorption surface;
When the direction perpendicular to the adsorption surface is the height direction, the internal electrode located at a position lower than the adsorption surface and higher than the recess in the substrate;
A conductive layer connected from the inside of the recess to the internal electrode ;
A member for electrostatic attraction comprising a feeding terminal inserted into the recess and connected to the conductive layer ,
An electrostatic attraction member characterized by having an opening in the bottom surface of the recess, an opening area in the bottom surface being smaller than an area of an end surface of the power supply terminal, and a hollow region extending from the bottom surface to the internal electrode .   The member for electrostatic attraction according to claim 1, wherein the conductive layer in the recess has a thread portion.   The electrostatic attraction member according to claim 1, further comprising a spiral conductive wire contacting the conductive layer in the recess. Wherein the conductive wire material, electrostatic attraction member according to 請 Motomeko 3, characterized in that it is fixed to the conductive layer in the recess via the bonding agent.   The conductive layer has a first layer mainly composed of titanium and a second layer mainly composed of titanium nitride, titanium carbide, or titanium carbonitride, and the second layer is positioned on the first layer. 5. The electrostatic attraction member according to claim 1, wherein the first layer is bonded to the base body made of ceramics. 6.   6. The electrostatic attraction member according to claim 1, wherein an arithmetic average roughness Ra of the attraction surface is 0.85 μm or less (excluding 0 μm).   The said base | substrate consists of the 1st structure which has the said adsorption surface, and the 2nd structure in which the said recessed part is located, The said 1st structure has a dielectric breakdown strength larger than the said 2nd structure. The member for electrostatic attraction according to claim 6. The base includes a first structure having the adsorption surface and a second structure in which the concave portion is located, and at least a part of a surface layer portion including the adsorption surface in the first structure is conductive or semiconductive. The member for electrostatic attraction in any one of Claims 1 thru | or 6 which has property.

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