JP6490004B2 - Electrode built-in substrate - Google Patents

Description

  The present invention relates to a substrate with a built-in electrode, for example, a substrate with a built-in electrode in which an electrode such as an electrostatic chuck electrode, a heater electrode, or a plasma electrode used in a semiconductor manufacturing apparatus is built.

  In manufacturing and inspection processes of semiconductor substrates such as silicon wafers and other various substrates, it is necessary to hold the substrates during various processes, measurements, and conveyances. For example, an etching process for performing microfabrication on a semiconductor wafer in a semiconductor manufacturing process, a film forming process for forming a thin film, an exposure processing process using a photoresist film, etc. are performed under vacuum, so that the wafer is held. An electrostatic chuck is used. Such an electrostatic chuck has a built-in heater function for processing at a predetermined temperature.

  For example, an electrostatic chuck uses a top surface of a dielectric layer made of a low thermal expansion ceramic as an adsorption surface of a wafer, and a voltage is applied between the electrostatic adsorption electrode (internal electrode) embedded in the dielectric layer and the wafer. The wafer is held on the suction surface by the obtained electrostatic suction force.

  Patent Document 1 describes a technique in which the electrode pattern of the internal electrode is concentric, and the temperature distribution on the wafer support surface is distributed concentrically to improve the thermal uniformity.

Japanese Patent No. 3477062

  Conventionally, an electrostatic chuck has been manufactured by sintering a base material using a plate-like punching metal as a material for an internal electrode. However, since the punching metal electrode has a flat plate shape, the punching metal electrode is poor in stretchability, and there is a problem that deformation of the electrode such as warpage is likely to occur.

  Therefore, in order to improve the adhesion between the substrate and the internal electrode, the internal electrode may be a mesh electrode made of a wire mesh. When a base material such as a ceramic in which a mesh electrode is embedded is sintered, the electrode hardly deforms due to the stretchability of the mesh electrode.

  However, since the mesh electrode is woven in a mesh shape, the resistance value has anisotropy. Specifically, the resistance value per unit length of the mesh electrode increases as the mesh electrode deviates from the mesh direction. Since the mesh electrode has the same mesh direction as a whole, when the internal electrodes are arranged concentrically as described in Patent Document 1, the resistance value in the radial direction of the electrostatic chuck varies greatly. Occurs. Therefore, periodic heat transfer unevenness occurs in the circumferential direction of the electrostatic chuck.

  This invention is made | formed in view of this situation, and when an internal electrode is a mesh electrode, it aims at providing the electrode built-in base material which can aim at cancellation of the heat-transfer nonuniformity in the circumferential direction.

  The present invention is an electrode-embedded base material in which an internal electrode made of a mesh electrode is embedded in an insulating base material, and the internal electrode is connected to a plurality of straight portions having the same width via a bent portion. A plurality of electrode patterns each having at least one opening are arranged concentrically, and the electrode patterns adjacent to each other in the radial direction are connected to each other, and a straight line of the electrode patterns adjacent to each other in the radial direction. The part is non-parallel.

  Since the internal electrode is a mesh electrode, the resistance value per unit length increases as it deviates from the direction in which the linear conductive material body extends. When the electrode patterns of the internal electrodes are arranged concentrically as described in Patent Document 1, the displacement angle with respect to the direction in which the linear conductive material body of the electrode pattern extends in the radial direction is the same. The resistance value in the radial direction of the pattern varies greatly in the circumferential direction.

  However, according to the present invention, the internal electrode has a plurality of linear portions having the same width connected via the bent portions, and each of the annular electrode patterns having at least one opening is concentric. The electrode patterns that are arranged and are adjacent in the radial direction are connected, and the linear portions of the electrode patterns that are adjacent in the radial direction are non-parallel.

  Therefore, for example, even if there is a straight line part whose angle is greatly deviated from the direction in which the linear conductive material constituting the mesh electrode extends in a part of the electrode pattern, a straight line adjacent to the straight line part in the radial direction. The angle at which the portion deviates from the direction in which the linear conductive material body extends is small. Therefore, the unevenness in the circumferential direction of the resistance value in the radial direction of the electrode-embedded substrate is smaller than that in the case of the concentric electrode pattern as in Patent Document 1, and the heat transfer unevenness in the circumferential direction of the electrode-embedded substrate. Can be suppressed.

  In the present invention, it is preferable that the plurality of electrode patterns are similar to each other, are regular polygons having at least one opening, and the electrode patterns adjacent in the radial direction are out of phase.

  In this case, the heat transfer unevenness in the circumferential direction of the electrode-embedded base material becomes periodic, and it becomes possible to easily suppress the heat transfer unevenness.

1 is a schematic top view showing internal electrodes of an electrostatic chuck according to an embodiment of the present invention. The schematic cross section of the II-II cross section of FIG. The enlarged top view for demonstrating a mesh electrode. The graph which shows the relationship between the shift | offset | difference angle (theta) from the direction where a linear conductive material body extends, and the resistance value R of the radial direction of a mesh electrode.

  First, an electrostatic chuck 100 according to an embodiment of a substrate with a built-in electrode of the present invention will be described with reference to FIGS. 1 and 2. In addition, the electrode built-in base material of the present invention may be one in which an electrode such as a heater electrode or a plasma electrode is built in the base material.

  The electrostatic chuck 100 includes a base material 10 made of a substantially disk-shaped insulator for attracting and holding a wafer (substrate) X. The base material 10 is a dielectric formed of a ceramic sintered body.

  The base material 10 is a ceramic sintered body made of, for example, alumina, aluminum nitride, magnesia spinel, or the like. The base material 10 may be formed into a disk shape by hot press firing or the like, for example, in order to form and densify the above material in a mold having a predetermined shape.

  An internal electrode 20 is embedded in the base material 10. The internal electrode 20 is composed of a mesh electrode made of a linear conductive material extending in a plurality of predetermined directions. The mesh electrode is formed by knitting a refractory metal wire such as molybdenum or tungsten into a fine mesh. Here, as shown in FIG. 3, the mesh electrode has a square shape, and the linear conductive material bodies extend in directions orthogonal to each other.

  However, the mesh of the mesh electrode is not limited to a square, and may be a rectangular shape such as a rectangle or a parallelogram, or may be a polygonal mesh such as a triangle, a hexagon, or an octagon. . The mesh electrode is not limited to a braided linear body made of a conductive material, and may be a meshed conductive material such as punching metal.

  The base material 10 is baked in a state where the internal electrode 20 is sandwiched between a portion above and below the internal electrode 20 of the base material 10.

  An example of the pattern of the internal electrode 20 will be described with reference to FIG.

  The internal electrode 20 is connected to a plurality of substantially concentric electrode patterns 21 a to 21 f arranged at intervals in the radial direction of the electrostatic chuck 100.

  Each electrode pattern 21a to 21e is divided into two parts, except for the outermost electrode pattern 21f. Each of the electrode patterns 21a to 21e is preferably a polygon that is similar to each other, particularly a regular polygon, except for a portion that is divided and opened. Here, the electrode patterns 21a to 21f are regular dodecagons, except for the divided and opened portions. Thus, each electrode pattern 21a-21f has the several linear part A connected via the bending part B. As shown in FIG.

  The linear portions A of the electrode patterns 21a to 21f have the same line width. However, the same line width includes the case where the line width is substantially the same. The bent part B may be angular or may have a curved part. The line width of the bent portion B may be the same as or different from the line width of the straight portion A.

  Here, the electrode patterns adjacent to each other in the radial direction, for example, the electrode pattern 21c and the electrode pattern 21d are out of phase by 15 degrees with respect to the center O of the electrode patterns 21a to 21f, and the sides adjacent in the radial direction are non-parallel. It has become. Thereby, the linear part A of electrode pattern 21a-21f adjacent to radial direction is non-parallel.

  The number of electrode patterns 21a to 21f is not limited to six and may be two or more. In addition, the shape of the electrode patterns 21a to 21f is not limited to a regular dodecagon having an open portion, and a polygon having an open portion and a corner portion (bent portion B) may have a curved portion. Good. However, if the shape of the electrode patterns 21a to 21f is a regular polygon, the arrangement design of the electrode patterns 21a to 21f is facilitated.

  In the electrode patterns 21a to 21f adjacent in the radial direction, the respective ends divided into two are alternately connected by the connection patterns 22a to 22e. For example, the end of the electrode pattern 21c and the end of the electrode pattern 21d are connected by the connection pattern 22c. The line widths of the connection patterns 22a to 22e are wider than the line widths of the electrode patterns 21a to 21f.

  The central electrode pattern 21 a is connected to two power supply patterns 23 connected to the power supply terminal 30.

  The electrostatic chuck 100 is formed with a through hole 40 through which a lift pin (not shown) is inserted. The through hole 40 is formed between the electrode patterns 21a to 21f.

  Since the internal electrode 20 is a mesh electrode obtained by knitting a refractory metal into a fine mesh, the resistance value R per unit length increases as it deviates from the direction in which the linear conductive material body extends. Specifically, referring to FIG. 3, the mesh electrode having the same length and the same width in the direction shifted by the angle θ from the mesh direction is θ with respect to the direction in which the linear conductive material body of the mesh electrode extends. The resistance value of the portion between the two-dot chain lines in FIG. However, FIG. 3 is a schematic diagram.

  For example, the mesh electrode is a plain weave having a wire diameter of 0.04 mm to 0.25 mm and a mesh size (number of wires per inch) of # 50 to # 300. The width of each electrode pattern 21a-21f is 3 mm to 30 mm.

  As shown in FIG. 4, the resistance value R increases as the angle θ from the extending direction of the linear conductive material body deviates.

  And as for the mesh electrode, the direction (mesh direction) in which the linear electroconductive material body extends in the whole is the same. Therefore, when the electrode patterns of the internal electrodes are arranged concentrically as described in Patent Document 1, a large variation occurs in the resistance value R in the radial direction of the electrostatic chuck. Specifically, in each circular electrode pattern, the resistance value R in a portion along the mesh is small, whereas the resistance value R in a portion shifted by an angle θ from the direction in which the linear conductive material body extends is It increases with the angle θ. Since this applies to each circular electrode pattern, the resistance value R in the radial direction of the electrostatic chuck has periodic unevenness in the circumferential direction. Therefore, uneven heat transfer occurs in the circumferential direction of the electrostatic chuck.

  On the other hand, in the electrostatic chuck 100 according to this embodiment, the internal electrode 20 has a plurality of polygonal electrode patterns 21a to 21f connected to each other, and a linear portion A adjacent in the radial direction of the electrode patterns 21a to 21f. Are non-parallel.

  Therefore, for example, even if there is a straight line portion A having an angle θ greatly deviated from the direction in which the linear conductive material body extends in a part of the electrode patterns 21a to 21f, the straight line portion adjacent to the straight line portion A in the radial direction. In A, the angle θ deviated from the extending direction of the linear conductive material body is small. Therefore, as a whole, the unevenness in the circumferential direction of the resistance value R in the radial direction of the electrostatic chuck 100 is small as compared with the case where a concentric electrode pattern is used as in Patent Document 1, and the electrostatic chuck 100 It is possible to suppress uneven heat transfer in the circumferential direction of 100.

  Furthermore, when it is set as a concentric electrode pattern like the said patent document 1, the space | interval between electrode patterns is the same in the circumferential direction of an electrostatic chuck. For this reason, when the through holes through which the lift pins are inserted are arranged between the electrode patterns, it is necessary to separate the electrode patterns so as to exceed the diameter of the through holes throughout.

  On the other hand, in the electrostatic chuck 100 according to the present embodiment, there are a plurality of electrode patterns 21a to 21f made of polygons and a wide portion and a narrow portion in the interval. Therefore, by arranging the through-holes 40 (see FIG. 2) in the wide gap portion, it is not necessary to keep the gap between the electrode patterns 21a to 21f as a whole, so that the gap between the electrode patterns 21a to 21f is limited. It becomes possible to reduce the fear.

  Further, the smaller the angle formed between the direction in which the linear conductive material body extends and the direction in which the side of the electrode pattern 21 extends, the greater the resistance value R in the radial direction at the side of the electrode pattern 21.

  Accordingly, the smaller the angle formed between the direction in which the linear conductive material body extends and the direction in which the linear portion A of the electrode pattern 21 extends, the wider the side of the electrode pattern 21 or the diameter of the electrode pattern 21 and the diameter. It is preferable to increase the distance between the electrode patterns 21 adjacent in the direction.

  As a result, it is possible to suppress uneven heat transfer in the circumferential direction of the electrostatic chuck 100.

  DESCRIPTION OF SYMBOLS 10 ... Base material, 20 ... Internal electrode, 21a-21f ... Electrode pattern, 22 ... Connection pattern, 23 ... Feeding pattern, 30 ... Feeding terminal, 40 ... Through-hole, 100 ... Electrostatic chuck (electrode built-in base material), A ... Linear part, B ... Bent part, X ... Wafer (substrate).

Claims (2)

An electrode built-in base material in which an internal electrode made of a mesh electrode is embedded in an insulating base material,
In the internal electrode, a plurality of linear portions having the same width are connected via a bent portion, and at least one open portion is arranged in a plurality of annular electrode patterns concentrically and adjacent in the radial direction. The electrode-embedded base material, wherein the electrode patterns are connected, and the linear portions of the electrode patterns adjacent in the radial direction are non-parallel.   2. The electrode pattern according to claim 1, wherein the plurality of electrode patterns are similar to each other, are regular polygons having at least one open position, and electrode patterns adjacent to each other in the radial direction are out of phase. Electrode built-in substrate.