JP2011049196A - Electrostatic chuck - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic chuck capable of uniformly heating or cooling an attraction object attracted to an attracting surface by uniforming the temperature distribution of the attracting surface. <P>SOLUTION: The electrostatic chuck 1 includes a ceramic insulating plate 10 and a metal base 30, and attracts the attraction object 2 to the attracting surface 11 using electrostatic attracting force generated when voltage is applied to an attracting electrode layer 51. The ceramic insulating plate 10 includes thereinside a heater electrode layer 61 and a cooling gas passage 41. The cooling gas passage 41 includes a horizontal hole 42 extending in the planar direction of the ceramic insulating plate 10. The attracting electrode layer 51 is disposed closed to the attracting surface 11 than to the horizontal hole 42 within the ceramic insulating plate 10, and the heater electrode layer 61 is disposed closer to a joining surface 12 side than to the horizontal hole 42 within the ceramic insulating plate 10. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electrostatic chuck used for fixing a semiconductor wafer, correcting the flatness of the semiconductor wafer, transporting the semiconductor wafer, and the like.

  Conventionally, in a semiconductor manufacturing apparatus, a process such as dry etching is performed on a semiconductor wafer (for example, a silicon wafer). In order to increase the accuracy of dry etching, it is necessary to securely fix the semiconductor wafer. Therefore, an electrostatic chuck for fixing the semiconductor wafer by electrostatic attraction has been proposed as a fixing means for fixing the semiconductor wafer (see, for example, Patent Document 1).

  Specifically, the electrostatic chuck described in Patent Document 1 has an adsorption electrode layer inside a ceramic insulating plate, and an electrostatic attraction generated when a voltage is applied to the adsorption electrode layer. Is used to adsorb the semiconductor wafer to the upper surface (adsorption surface) of the ceramic insulating plate. This electrostatic chuck is configured by bonding a metal base to the lower surface (bonding surface) of a ceramic insulating plate.

  In recent years, it is also considered that the electrostatic chuck has a function of adjusting (heating or cooling) the temperature of the semiconductor wafer adsorbed on the adsorption surface. For example, there is a technique of heating a semiconductor wafer on an adsorption surface by providing a heater electrode layer in a ceramic insulating plate and heating the ceramic insulating plate with the heater electrode layer. Further, in Patent Document 1, a cooling gas passage opening at the adsorption surface is provided in the ceramic insulating plate, and a cooling gas (for example, helium gas) flowing through the cooling gas passage is brought into contact with the semiconductor wafer on the adsorption surface. Thus, a technique for cooling a semiconductor wafer is disclosed. Further, in Patent Document 1, a cooling fluid channel is provided in a metal base, and a ceramic insulating plate is cooled with a cooling fluid (for example, cooling water) flowing through the cooling fluid channel, thereby providing a semiconductor wafer on the adsorption surface. A technique for cooling the battery is also disclosed.

JP 2008-205510 A (FIG. 1 etc.)

  By the way, when the electrostatic chuck is provided with the temperature adjusting function, that is, as shown in FIG. 5, the heater electrode layer 81, the cooling gas passage 82 and the cooling fluid passage 83 are provided in the electrostatic chuck 80. In many cases, the heater electrode layer 81 is disposed on the lower layer side of the adsorption electrode layer 85 in the ceramic insulating plate 84, and the cooling gas flow path 82 is disposed on the lower layer side of the heater electrode layer 81. When the ceramic insulating plate 84 is viewed from the thickness direction, the region where the cooling gas flow path 82 exists is the existence region A1, and the region where the cooling gas flow channel 82 does not exist is the non-existence region A2.

  However, in the above case, the cooling gas flow path 82 is disposed between the heater electrode layer 81 and the cooling fluid flow path 83. In this case, in the non-existing region A2, the heat generated from the heater electrode layer 81 is transmitted to the cooling fluid channel 83 side (see the arrow F1 in FIG. 5), so the cooling fluid flowing through the cooling fluid channel 83 Thus, the ceramic insulating plate 84 can be reliably cooled. However, in the existence region A1, since the heat transfer generated from the heater electrode layer 81 is blocked by the cooling gas flow path 82 (see arrow F2 in FIG. 5), the ceramic insulating plate 84 is cooled by the cooling fluid. Is difficult. That is, since the existence area A1 is less likely to be cooled than the non-existence area A2, the temperature distribution on the adsorption surface 86 becomes non-uniform, and the semiconductor wafer adsorbed on the adsorption surface 86 cannot be uniformly heated or cooled. Therefore, for example, when a pattern is formed on a semiconductor wafer by performing dry etching, problems such as variations in the degree of processing are likely to occur, resulting in a decrease in yield.

  Moreover, the heater electrode layer 81 is disposed closer to the adsorption surface 86 than the cooling gas flow path 82, and the distance between the heater electrode layer 81 and the adsorption surface 86 is short. Therefore, the heat generated from the heater electrode layer 81 reaches the adsorption surface 86 with almost no diffusion (see arrow F3 in FIG. 5). As a result, the temperature distribution in the inner layer portion where the heater electrode layer 81 exists is reflected as the temperature distribution of the adsorption surface 86 as it is. That is, in addition to the arrangement of the cooling gas flow path 82, there is a problem in the arrangement of the heater electrode layer 81, so that the temperature distribution of the adsorption surface 86 becomes non-uniform, and thus the semiconductor wafer adsorbed on the adsorption surface 86. It becomes very difficult to uniformly heat or cool the.

  The present invention has been made in view of the above problems, and an object thereof is to uniformly heat or cool an object to be adsorbed on the adsorption surface by making the temperature distribution on the adsorption surface uniform. It is to provide an electrostatic chuck.

  As means for solving the above problems, a ceramic insulating plate having a first main surface and a second main surface and having a plurality of ceramic layers laminated, and having an adsorption electrode layer therein, and the ceramic insulation A metal base that is bonded to the second main surface side of the plate via an adhesive layer, and the object to be adsorbed by the electrostatic attraction generated when a voltage is applied to the adsorption electrode layer. In the electrostatic chuck to be adsorbed on one main surface, the ceramic insulating plate is cooled by a heater electrode layer that heats the ceramic insulating plate and a cooling gas that cools an object to be adsorbed on the first main surface. A cooling gas flow path through which a cooling fluid for cooling the ceramic insulating plate flows, and the cooling gas flow path is formed of the ceramic insulation. Plane direction of plate The suction electrode layer is disposed closer to the first main surface than the lateral hole in the ceramic insulating plate, and the heater electrode layer is disposed in the ceramic insulating plate from the lateral hole. An electrostatic chuck is provided on the second main surface side.

  Therefore, according to the electrostatic chuck of the above means, the heater electrode layer is disposed on the second main surface side (opposite side of the first main surface side which is the adsorption surface) from the side hole of the cooling gas flow path. There is no layer (horizontal hole) that becomes a space between the heater electrode layer and the cooling fluid flow path. As a result, the heat generated from the heater electrode layer is transmitted to the cooling fluid flow path side without being blocked by the lateral holes, so that the ceramic insulating plate can be reliably cooled by the cooling fluid flowing through the cooling fluid flow path. it can. As a result, since the temperature distribution on the first main surface becomes uniform, the object to be adsorbed on the first main surface can be heated or cooled uniformly.

  In addition, as described above, the heater electrode layer is disposed on the second main surface side of the lateral hole, and the distance between the heater electrode layer and the first main surface is increased, so that the heat generated from the heater electrode layer is reduced. Sufficient distance is secured for diffusion. Therefore, the heat generated from the heater electrode layer is reliably diffused as it is transmitted to the first main surface side. As a result, on the first main surface, the difference between the temperature of the region immediately above the heater electrode layer and the temperature of the region not directly above the heater electrode layer is reduced. That is, not only devising the positional relationship between the heater electrode layer and the lateral hole, but also by devising the positional relationship between the heater electrode layer and the first main surface, the temperature distribution of the first main surface becomes uniform, The object to be adsorbed on the first main surface can be heated or cooled more uniformly.

  Here, the thickness of the ceramic insulating plate is not particularly limited, but may be, for example, 2 mm or more and 7 mm or less. When the thickness of the ceramic insulating plate is less than 2 mm, the heat transmitted through the ceramic insulating plate is not sufficiently diffused, and the temperature distribution on the first main surface may become non-uniform. Moreover, since the ceramic insulating plate becomes too thin, the strength of the ceramic insulating plate may be reduced and damaged. On the other hand, when the thickness of the ceramic insulating plate is larger than 7 mm, heat is not easily transmitted through the ceramic insulating plate, so that the heating efficiency and cooling efficiency of the first main surface may be reduced. In this case, it takes time to adjust the temperature of the object to be adsorbed on the first main surface.

  In addition, as a material constituting the ceramic insulating plate (the ceramic layer), a sintered body mainly composed of a high-temperature fired ceramic such as alumina, yttria (yttrium oxide), aluminum nitride, boron nitride, silicon carbide, silicon nitride, or the like. Etc. Depending on the application, a sintered body mainly composed of a low-temperature fired ceramic such as a glass ceramic obtained by adding an inorganic ceramic filler such as alumina to a borosilicate glass or a lead borosilicate glass may be selected. Alternatively, a sintered body mainly composed of a dielectric ceramic such as barium titanate, lead titanate, or strontium titanate may be selected.

  In each process such as dry etching in semiconductor manufacturing, various techniques using plasma are employed, and in processes using plasma, corrosive gas such as halogen gas is frequently used. For this reason, high corrosion resistance is required for the electrostatic chuck exposed to corrosive gas or plasma. Therefore, the ceramic insulating plate is preferably made of a material having corrosion resistance against corrosive gas or plasma, for example, a material mainly composed of alumina or yttria. In this way, since the corrosion of the first main surface of the ceramic insulating plate can be prevented, the flatness of the first main surface is hardly lowered, and the life of the electrostatic chuck can be extended.

  The ceramic insulating plate has the adsorption electrode layer and the heater electrode layer inside. The material constituting the adsorption electrode layer and the heater electrode layer is not particularly limited, but when these conductors and ceramic layers are formed by a simultaneous firing method, the metal powder in the conductor has a melting point higher than the firing temperature of the ceramic layers. Need to be. For example, when the ceramic layer is made of a so-called high-temperature fired ceramic (for example, alumina), the metal powder in the conductor includes nickel (Ni), tungsten (W), molybdenum (Mo), manganese (Mn), etc. An alloy can be selected. When the ceramic layer is made of a so-called low-temperature fired ceramic (for example, glass ceramic), copper (Cu), silver (Ag), or the like or an alloy thereof can be selected as the metal powder in the conductor. Further, when the ceramic layer is made of a high dielectric constant ceramic (for example, barium titanate), nickel (Ni), copper (Cu), silver (Ag), palladium (Pd), platinum (Pt), etc. An alloy can be selected. The adsorption electrode layer and the heater electrode layer are formed by applying a conductive paste containing a metal powder and applying the paste by a well-known method such as a printing method, followed by baking.

  In addition, although it does not specifically limit as a cross-sectional shape of a heater electrode layer, It is preferable that it is a cross-sectional rectangular shape which is a general shape. If the heater electrode layer has a rectangular cross section, the heat generated by the heater electrode layer is easily released to the first main surface side, so that the heating efficiency of the first main surface is improved. Further, the shape of the heater electrode layer in a plan view is not particularly limited. For example, the heater electrode layer may have a spiral shape in a plan view or a concentric shape in a plan view.

Furthermore, the area resistivity of the heater electrode layer is not particularly limited, but may be, for example, 0.1 mΩ / cm ² or more and 50 Ω / cm ² or less. If the area resistivity is less than 0.1 mΩ / cm ² , the resistivity is too small and the amount of heat generation becomes small, so that there is a possibility that the ceramic insulating plate cannot be heated well by the heater electrode layer. On the other hand, if the sheet resistivity is higher than 50 Ω / cm ² , the amount of heat generated with respect to the applied voltage may be too large, making it difficult to control the amount of heat generated.

  In addition, the ceramic insulating plate has a cooling gas flow path through which a cooling gas flows. Here, examples of the cooling gas include inert gases such as helium gas and nitrogen gas. In addition, when the horizontal hole provided in the ceramic insulating plate extends radially from the center portion of the ceramic insulating plate toward the outer peripheral portion, the heater electrode layer is formed when the ceramic insulating plate is viewed from the thickness direction. It is preferably arranged mainly in a region that does not overlap the lateral hole, and more preferably, it is disposed so as not to overlap the lateral hole at all when the ceramic insulating plate is viewed from the thickness direction. In this way, the heat generated from the heater electrode layer is transmitted to the first main surface without being blocked by the side holes, and therefore the object to be adsorbed on the first main surface can be efficiently heated.

  The cooling gas flow path further includes a vertical hole that communicates with the horizontal hole and extends in the thickness direction of the ceramic insulating plate, and the metal base communicates with the vertical hole and extends in the thickness direction of the metal base. A communication hole may be provided, the vertical hole may be disposed so as to avoid the heater electrode layer, and the communication hole may be disposed so as to avoid the cooling fluid flow path. In this case, it is not necessary to consider the position of the vertical hole when arranging the heater electrode layer, and it is not necessary to consider the position of the communication hole when arranging the cooling fluid flow path. The degree of freedom in designing the chuck is increased.

  Furthermore, examples of the material for forming the metal base include copper, aluminum, iron, and titanium. The material for forming the adhesive layer is preferably a material having a large force for joining the ceramic insulating plate and the metal base. For example, a metal material such as indium, silicone resin, acrylic resin, epoxy resin, polyimide resin A resin material such as a polyamideimide resin or a polyamide resin can be selected. However, since the difference between the thermal expansion coefficient of the ceramic insulating plate and the thermal expansion coefficient of the metal base is large, the adhesive layer is particularly preferably made of an elastically deformable resin material having a function as a buffer material.

1 is a perspective view showing a partially broken electrostatic chuck according to an embodiment of the present invention. FIG. 3 is a perspective view showing a partially broken electrostatic chuck. The schematic sectional drawing which shows an electrostatic chuck. Explanatory drawing which shows the positional relationship of a heater electrode layer and the gas flow path for cooling. The schematic sectional drawing which shows the electrostatic chuck in a prior art.

  Hereinafter, an embodiment embodying the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the electrostatic chuck 1 of the present embodiment is an apparatus for adsorbing a semiconductor wafer 2 (adsorbed object) to an adsorption surface 11. The electrostatic chuck 1 includes a ceramic insulating plate 10 and a metal base 30 bonded to the bonding surface 12 side of the ceramic insulating plate 10 via an adhesive layer 20. The adhesive layer 20 of this embodiment is an adhesive made of a silicone resin (resin material), and the thickness of the adhesive layer 20 is set to 300 μm. In the present embodiment, the adhesive layer 20 has a thermal conductivity of 0.16 W / (m · K) and a thermal expansion coefficient of about 200 ppm / ° C. The thermal expansion coefficient of the adhesive layer 20 refers to an average value of measured values between 0 ° C. and the glass transition temperature (Tg).

  As shown in FIGS. 1 to 3, the ceramic insulating plate 10 has a substantially disk shape with a diameter of 300 mm and a thickness of 3.0 mm. The ceramic insulating plate 10 has a suction surface 11 that is a first main surface and a bonding surface 12 that is a second main surface. The ceramic insulating plate 10 is made of a sintered body mainly composed of alumina and has a structure in which six ceramic layers 13 to 18 are laminated. In the present embodiment, the ceramic insulating plate 10 has a thermal conductivity of 32 W / (m · K) and a thermal expansion coefficient of 7.7 ppm / ° C. In addition, the thermal expansion coefficient of the ceramic insulating board 10 says the average value of the measured value between 30 degreeC-250 degreeC.

  Further, the ceramic insulating plate 10 has a cooling gas passage 41 inside. In the cooling gas channel 41, helium gas (cooling gas) for cooling the semiconductor wafer 2 adsorbed on the adsorption surface 11 flows. The cooling gas flow path 41 includes a plurality of lateral holes 42 extending in the plane direction of the ceramic insulating plate 10 in the third ceramic layer 15. Each horizontal hole 42 is disposed in a layer closer to the suction surface 11 than a heater electrode layer 61 described later. Each lateral hole 42 has a rectangular cross section, and the length in the thickness direction of the ceramic insulating plate 10 is set to 0.5 mm or more and 1.5 mm or less (1.0 mm in this embodiment). The length in the plane direction is set to 1.0 mm. The horizontal holes 42 are arranged at equal angular intervals (60 °) with respect to the central portion C1 of the ceramic insulating plate 10, and extend radially from the central portion C1 toward the outer peripheral portion (see FIG. 4).

  As shown in FIG. 1 and FIG. 3, the cooling gas passage 41 includes a pair of annular gas passages 43 and 44 and both annular gas passages 43 and 44 in the first ceramic layer 13. A plurality of connected gas flow paths 45 that connect each other are provided. Both annular gas flow paths 43 and 44 are 0.05 mm in length in the thickness direction, have a rectangular cross section with a length in the plane direction of 1.5 mm, and are viewed in plan with respect to the center portion C1. They are arranged concentrically. The annular gas channel 44 on the outer peripheral side is provided with a plurality of gas ejection ports 46 that open at the adsorption surface 11. Each gas ejection port 46 has a circular shape and is arranged at equiangular intervals with respect to the center portion C1. Each connecting gas channel 45 is 0.05 mm in length in the thickness direction and has a rectangular cross-section with a length in the plane direction of 1.5 mm, and is equiangular with respect to the center portion C1 ( 120 [deg.] And spaced radially from the center C1 toward the outer periphery.

  As shown in FIGS. 1 and 3, the cooling gas flow path 41 further includes vertical holes 47, 48, and 49 that extend in the thickness direction of the ceramic insulating plate 10. The vertical hole 47 on the inner peripheral side has a diameter of 0.5 mm, and the end on the adsorption surface 11 side communicates with the annular gas flow path 43, while the end on the joining surface 12 side communicates with the horizontal hole 42. . Similarly, the inner peripheral side vertical hole 49 has a diameter of 2.0 mm, and the end on the suction surface 11 side communicates with the communication portion between the vertical hole 47 and the horizontal hole 42, while the end on the joining surface 12 side has the joining surface 12. Open at. Further, the vertical hole 48 on the outer peripheral side has a diameter of 0.5 mm, and the end on the adsorption surface 11 side communicates with the annular gas flow path 44, while the end on the joining surface 12 side communicates with the horizontal hole 42. Yes. And the vertical holes 47-49 are arrange | positioned avoiding the heater electrode layer 61 mentioned later.

  As shown in FIGS. 1 to 3, the ceramic insulating plate 10 has an adsorption electrode layer 51 inside. The adsorption electrode layer 51 is a layer formed of tungsten as a main component, and in the ceramic insulating plate 10, the adsorption surface 11 side of the lateral hole 42 (specifically, on the third ceramic layer 15). Is arranged. As shown in FIG. 2, the adsorption electrode layer 51 is electrically connected to the upper end surface of the through-hole conductor 52 that penetrates the third to fifth ceramic layers 15 to 17. Is connected electrically to a first pad (not shown) formed on the lower surface of the ceramic layer 17. Further, a first opening 53 exposing the first pad is formed at a predetermined position of the sixth ceramic layer 18, and the first terminal pin 54 is brazed or soldered on the surface of the first pad. Are joined by. The first terminal pin 54 is accommodated in a recess 55 provided in the metal base 30. A voltage is applied to the first terminal pin 54 with an external terminal (not shown) joined.

  As shown in FIGS. 1 to 3, the ceramic insulating plate 10 has a plurality of heater electrode layers 61 for heating the ceramic insulating plate 10 therein. Each heater electrode layer 61 is a layer formed of tungsten as a main component, and in the ceramic insulating plate 10, the side of the bonding surface 12 with respect to the lateral hole 42 (specifically, on the sixth ceramic layer 18). Is arranged. Thereby, the distance from the heater electrode layer 61 to the adsorption surface 11 is longer than the distance from the heater electrode layer 61 to the bonding surface 12. As shown in FIG. 4, each heater electrode layer 61 is arranged in a spiral shape in plan view with respect to the center portion C <b> 1. As a result, each heater electrode layer 61 intersects the horizontal hole 42, so that it hardly overlaps the horizontal hole 42 when the ceramic insulating plate 10 is viewed from the thickness direction. As shown in FIG. 2, the heater electrode layer 61 is electrically connected to a second pad (not shown) formed on the lower surface of the ceramic layer 17. Further, a second opening 62 for exposing the second pad is formed at a predetermined position of the sixth ceramic layer 18, and the second terminal pin 63 is brazed or soldered on the surface of the second pad. Are joined by. The second terminal pin 63 is accommodated in a recess 64 provided in the metal base 30. A voltage is applied to the second terminal pin 63 in a state where an external terminal (not shown) is joined.

  As shown in FIGS. 1 to 3, the metal base 30 is made of a material mainly composed of aluminum. In the present embodiment, the metal base 30 has a thermal conductivity of 236 W / (m · K) and a thermal expansion coefficient of about 23 ppm / ° C. In addition, the thermal expansion coefficient of the metal base 30 means the average value of the measured value between 0 degreeC and glass transition temperature (Tg). The metal base 30 has a substantially disk shape with a diameter of 340 mm and a thickness of 20 mm. That is, the diameter of the metal base 30 is set larger than the diameter (300 mm) of the ceramic insulating plate 10. The metal base 30 has a first surface 31 to which the ceramic insulating plate 10 is joined, and a second surface 32 located on the opposite side of the first surface 31.

  The metal base 30 has cooling fluid flow paths 71 and 72 inside. Cooling water (cooling fluid) for cooling the ceramic insulating plate 10 flows through the cooling fluid flow paths 71 and 72. Each of the cooling fluid channels 71 and 72 is arranged in a spiral shape in a plan view with respect to the central portion C1. The cooling fluid flow path 71 on the inner peripheral side is provided with a plurality of cooling water passages 73 that open at the second surface 32. Further, the cooling fluid passage 72 on the outer peripheral side extends to the outer peripheral side from the ceramic insulating plate 10 when the ceramic insulating plate 10 and the metal base 30 are viewed from the thickness direction.

  As shown in FIGS. 1 and 3, the metal base 30 includes a communication hole 33 having a diameter of 3.0 mm that extends in the thickness direction of the metal base 30. Helium gas is supplied to the communication hole 33 via an external pipe (not shown). In the communication hole 33, the end on the first surface 31 side communicates with the vertical hole 49, while the end on the second surface 32 side opens at the second surface 32. The communication hole 33 is arranged avoiding the cooling fluid flow paths 71 and 72. Specifically, the communication hole 33 is disposed between the cooling fluid channel 71 and the cooling fluid channel 72.

  When the electrostatic chuck 1 of this embodiment is used, a voltage of 3 kV is applied to the suction electrode layer 51 to generate an electrostatic attraction, and the semiconductor wafer 2 is sucked using the generated electrostatic attraction. Adsorbed on the surface 11. At this time, helium gas flowing through the cooling gas flow path 41 is supplied from the gas outlet 46 between the adsorption surface 11 and the back surface of the semiconductor wafer 2 to cool the semiconductor wafer 2. In addition, by applying a voltage to the heater electrode layer 61 to heat the ceramic insulating plate 10, the semiconductor wafer 2 adsorbed on the adsorption surface 11 is heated.

  Next, a method for manufacturing the electrostatic chuck 1 will be described.

First, a slurry is prepared by the following procedure. By mixing MgO (1% by weight), CaO (1% by weight), SiO ₂ (6% by weight) with alumina powder (92% by weight), wet-grinding with a ball mill for 50 to 80 hours, and then dehydrating and drying. Get powder. Next, methacrylic acid isobutyl ester (3% by weight), butyl ester (3% by weight), nitrocellulose (1% by weight), dioctyl phthalate (0.5% by weight) were added to the obtained powder, and further trichloroethylene, After adding n-butanol as a solvent, wet mixing is performed with a ball mill to obtain a slurry as a starting material for forming an alumina green sheet.

  Next, this slurry is degassed under reduced pressure, and then poured onto a releasable support (not shown) and cooled to evaporate the solvent. As a result, first to sixth alumina green sheets (non-sintered ceramic layers to be ceramic layers 13 to 18) having a thickness of 0.8 mm are formed. The second and third layers of alumina green sheets are provided with through holes for forming vertical holes 47 and 48, and the fifth and sixth layers of alumina green sheets are formed with vertical holes 49. A through hole is provided. The first layer of alumina green sheet is provided with through holes for forming the annular gas passages 43 and 44 and the connecting gas passage 45, and the fourth layer of alumina green sheet is provided with a lateral hole 42. A through-hole for forming is provided. Further, the sixth layer of alumina green sheet is provided with through holes for forming the recesses 55 and 64. The third to fifth layers of alumina green sheets are provided with through holes for forming the through-hole conductors 52. Each through hole is formed by die cutting or machining an alumina green sheet.

  Moreover, tungsten powder is mixed with the powder for alumina green sheets described above. This is made into a slurry by the same method as that for producing the alumina green sheet to obtain a metallized paste.

  Next, a metallized paste to be the adsorption electrode layer 51 is printed and applied on the upper surface of the third layer of alumina green sheet using a conventionally known paste printing apparatus (for example, a screen printing apparatus). Further, a metallized paste to be the heater electrode layer 61 is printed and applied on the upper surface of the sixth layer of alumina green sheet using a paste printing apparatus. Further, a metallized paste to be a through-hole conductor 52 is printed and applied in a through-hole provided in the third to fifth layers of alumina green sheets. Further, a metallized paste to be the first pad and the second pad is printed on the lower surface of the sixth layer of alumina green sheet. Thereafter, the printed metallized paste is dried.

  Next, the first to sixth layers of alumina green sheets are thermocompression-bonded in a state where the through holes are aligned so that the cooling gas passage 41, the openings 53 and 62, and the through-hole conductors 52 are formed. Then, a green sheet laminate having a thickness of about 5 mm is formed. Further, the green sheet laminate is cut into a predetermined disc shape (in this embodiment, a disc shape having a diameter of 300 mm).

  Next, the green sheet laminate is degreased in the atmosphere at 250 ° C. for 10 hours, and further fired in a reducing atmosphere at 1400 to 1600 ° C. for a predetermined time. As a result, alumina and tungsten are simultaneously sintered, and the ceramic insulating plate 10 having a desired structure is obtained. Since the size is reduced by about 20% by this firing, the thickness of the ceramic insulating plate 10 is about 4 mm. Thereafter, both the front and back surfaces of the ceramic insulating plate 10 are polished, so that the thickness of the ceramic insulating plate 10 is 3 mm, and the flatness of the suction surface 11 is 30 μm or less.

  Next, nickel plating is applied to the terminal pins 54, 63, and the ceramic insulating plate 10 is completed by brazing or soldering the nickel-plated terminal pins 54, 63 to the first and second pads. . Thereafter, when the ceramic insulating plate 10 is bonded to the metal base 30 via the adhesive layer 20, the electrostatic chuck 1 is completed.

  Therefore, according to the present embodiment, the following effects can be obtained.

  (1) According to the electrostatic chuck 1 of the present embodiment, since the heater electrode layer 61 is disposed closer to the joining surface 12 than the lateral hole 42 of the cooling gas passage 41, the heater electrode layer 61 and the cooling fluid A layer (horizontal hole 42) that becomes a space does not exist between the flow paths 71 and 72. As a result, the heat generated from the heater electrode layer 61 is transmitted to the cooling fluid flow paths 71 and 72 without being blocked by the lateral holes 42, so that the ceramic insulation is provided by the cooling water flowing through the cooling fluid flow paths 71 and 72. The plate 10 can be reliably cooled. As a result, since the temperature distribution on the suction surface 11 becomes uniform, the semiconductor wafer 2 sucked on the suction surface 11 can be uniformly heated or cooled.

  In addition, as described above, the heater electrode layer 61 is disposed on the bonding surface 12 side with respect to the lateral hole 42, and the distance between the heater electrode layer 61 and the suction surface 11 becomes longer, and thus the heater electrode layer 61 is generated from the heater electrode layer 61. Sufficient distance is secured for heat diffusion. Therefore, the heat generated from the heater electrode layer 61 is reliably diffused as it is transmitted to the adsorption surface 11 side. As a result, on the suction surface 11, the difference between the temperature of the region directly above the heater electrode layer 61 and the temperature of the region not directly above the heater electrode layer 61 is reduced. That is, not only the positional relationship between the heater electrode layer 61 and the horizontal hole 42 is devised but also the temperature distribution on the adsorption surface 11 is made uniform by devising the positional relationship between the heater electrode layer 61 and the adsorption surface 11. Specifically, the temperature difference between the region directly above the heater electrode layer 61 and the region not directly above is 0.04 ° C. (prior art is 0.72 ° C.) in this embodiment. Therefore, the semiconductor wafer 2 adsorbed on the adsorption surface 11 can be heated or cooled more uniformly.

  (2) Since the ceramic insulating plate 10 of the present embodiment is made of a material mainly composed of alumina for which a ceramic green sheet molding technique (that is, a molding technique of the ceramic layers 13 to 18) has been established, a cooling gas The flow path 41, the adsorption electrode layer 51, the heater electrode layer 61, and the like can be easily formed. In addition, since the metal base 30 of the present embodiment is made of a metal material (aluminum in the present embodiment) that can be finely processed, the cooling fluid channels 71 and 72 can be easily formed. Moreover, since the metal material is excellent in thermal conductivity, the ceramic insulating plate 10 can be effectively cooled using the cooling water flowing through the cooling fluid flow paths 71 and 72.

  (3) The adhesive layer 20 of the present embodiment is made of a silicone resin having a relatively low thermal conductivity. Accordingly, heat is hardly transmitted between the ceramic insulating plate 10 and the metal base 30, so that the ceramic insulating plate 10 is not excessively cooled by the cooling water flowing through the cooling fluid flow paths 71 and 72. That is, in order to reliably cool the ceramic insulating plate 10, it is necessary to suppress the output of the heater electrode layer 61. As a result, there is a temperature difference between a region directly above the heater electrode layer 61 and a region not directly above. Even smaller. Therefore, the semiconductor wafer 2 adsorbed on the adsorption surface 11 can be heated or cooled more uniformly.

  In addition, you may change this embodiment as follows.

  -Although the ceramic insulating board 10 of the said embodiment consisted of the material which has an alumina as a main component, it may consist of the material which has a yttria as a main component, for example. It should be noted that yttria is superior to alumina in corrosion resistance against plasma and corrosive gas frequently used in the manufacture of semiconductors. Therefore, if the ceramic insulating plate 10 is formed of yttria, the adsorption surface 11 can be more reliably prevented from corroding, and the flatness of the adsorption surface 11 is further less likely to be lowered, thereby further extending the life of the electrostatic chuck. be able to.

  In the electrostatic chuck 1 of the above embodiment, the semiconductor wafer 2 is the object to be adsorbed, but another member such as a liquid crystal panel may be the object to be adsorbed.

  Next, the technical ideas grasped by the embodiment described above are listed below.

  (1) A ceramic insulating plate having a first main surface and a second main surface and having a plurality of ceramic layers laminated, and having an adsorption electrode layer therein; and on the second main surface side of the ceramic insulating plate An electrostatic chuck comprising: a metal base bonded through an adhesive layer, wherein the object to be adsorbed is adsorbed to the first main surface using an electrostatic attraction generated when a voltage is applied to the adsorption electrode layer The ceramic insulating plate has a heater electrode layer for heating the ceramic insulating plate and a cooling gas passage through which a cooling gas for cooling the adsorbed material adsorbed on the first main surface flows. The metal base includes therein a cooling fluid passage through which a cooling fluid for cooling the ceramic insulating plate flows, and the cooling gas passage includes a lateral hole extending in a planar direction of the ceramic insulating plate. The electrode layer for adsorption is The ceramic insulating plate is disposed closer to the first main surface than the horizontal hole, and the heater electrode layer is disposed closer to the second main surface than the horizontal hole in the ceramic insulating plate. The insulating plate and the metal base are disk-shaped, the diameter of the metal base is set larger than the diameter of the ceramic insulating plate, and when the ceramic insulating plate and the metal base are viewed from the thickness direction, An electrostatic chuck characterized in that a cooling fluid channel extends to the outer peripheral side of the ceramic insulating plate.

  (2) A ceramic insulating plate having a first main surface and a second main surface and having a plurality of ceramic layers laminated, and having an adsorption electrode layer therein; and on the second main surface side of the ceramic insulating plate An electrostatic chuck comprising: a metal base bonded through an adhesive layer, wherein the object to be adsorbed is adsorbed to the first main surface using an electrostatic attraction generated when a voltage is applied to the adsorption electrode layer The ceramic insulating plate is made of a material mainly composed of alumina, and includes a heater electrode layer for heating the ceramic insulating plate, and a cooling gas for cooling the adsorbed material adsorbed on the first main surface. A cooling gas flow path that flows inside, the adhesive layer is an adhesive made of silicone resin, the metal base is made of a material mainly composed of aluminum, and the ceramic insulating plate A cooling fluid flow path through which a cooling fluid to be rejected flows, wherein the cooling gas flow path includes a horizontal hole extending in a planar direction of the ceramic insulating plate, and the adsorption electrode layer is formed of the ceramic insulating plate. The heater electrode layer is disposed closer to the second principal surface than the lateral hole in the ceramic insulating plate, and the heater electrode layer is disposed closer to the second principal surface than the lateral hole. Electric chuck.

DESCRIPTION OF SYMBOLS 1 ... Electrostatic chuck 2 ... Semiconductor wafer 10 as a to-be-adsorbed object ... Ceramic insulating plate 11 ... Adsorption surface 12 as a 1st main surface ... Joining surface 13, 14, 15, 16, 17, 18 as a 2nd main surface ... Ceramic layer 20 ... Adhesive layer 30 ... Metal base 33 ... Communication hole 41 ... Cooling gas flow path 42 ... Horizontal holes 47, 48, 49 ... Vertical holes 51 ... Adsorption electrode layer 61 ... Heater electrode layers 71, 72 ... For cooling Fluid flow path C1... Central part

Claims (5)

A ceramic insulating plate having a first main surface and a second main surface and having a plurality of ceramic layers laminated, and having an adsorption electrode layer therein, and an adhesive layer on the second main surface side of the ceramic insulating plate An electrostatic chuck for adsorbing an object to be adsorbed to the first main surface using an electrostatic attraction generated when a voltage is applied to the electrode layer for adsorption.
The ceramic insulating plate includes therein a heater electrode layer that heats the ceramic insulating plate, and a cooling gas passage through which a cooling gas that cools an adsorbed object adsorbed on the first main surface flows.
The metal base has a cooling fluid passage in which a cooling fluid for cooling the ceramic insulating plate flows,
The cooling gas flow path includes a lateral hole extending in a planar direction of the ceramic insulating plate,
The adsorption electrode layer is disposed on the first main surface side of the horizontal hole in the ceramic insulating plate, and the heater electrode layer is positioned on the second main surface of the ceramic insulating plate than the horizontal hole. An electrostatic chuck that is disposed on a side. The cooling gas flow path further includes a vertical hole communicating with the horizontal hole and extending in the thickness direction of the ceramic insulating plate,
The metal base includes a communication hole that communicates with the vertical hole and extends in the thickness direction of the metal base;
The electrostatic chuck according to claim 1, wherein the vertical hole is disposed so as to avoid the heater electrode layer, and the communication hole is disposed so as to avoid the cooling fluid flow path.   The electrostatic chuck according to claim 1, wherein the ceramic insulating plate is made of a material mainly composed of alumina.   The electrostatic chuck according to claim 1, wherein the adhesive layer is made of a resin material. The lateral holes extend radially from the center of the ceramic insulating plate toward the outer periphery,
6. The static electricity according to claim 1, wherein the heater electrode layer is mainly disposed in a region that does not overlap the lateral hole when the ceramic insulating plate is viewed from a thickness direction. Electric chuck.

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