JP2018056237A - Object mounting member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an object mounting member having a ventilation passage leading to the outside through an opening, the member suppressing a local temperature reduction in a mounting surface when the surface is heated, thereby keeping the surface at a uniform temperature.SOLUTION: The object mounting member includes: a base body having a mounting surface, on which an object is to be mounted; a ventilation passage in the base body, the base body leading to the outside through an opening in the mounting surface; and a heater in the base body or below the back surface of the base body opposite to the mounting surface, the ventilation passage including at least a part of a ventilation member with an air permeability in a position opposed to the object when the object is mounted on the mounting surface, the position being closer to the mounting surface than to the heater.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an object mounting member such as a ceramic heater used for mounting and heating an object in a semiconductor manufacturing apparatus or the like.

  2. Description of the Related Art In a semiconductor manufacturing apparatus such as CVD, a ceramic heater (object mounting member) in which a resistance heating element is embedded in a substrate is used for mounting and fixing a wafer (object) and heat-treating it. The ceramic heater has a base having a mounting surface for mounting a wafer, a heating element disposed inside the base for heating to, for example, 500 ° C., and a wafer fixed to the mounting surface as necessary. A vacuum suction mechanism, an electrostatic suction mechanism, and the like. Among these, the vacuum suction mechanism is, for example, formed in the substrate and draws a vacuum on a ventilation path leading to a plurality of openings provided on the mounting surface, thereby generating a negative pressure between the mounting surface and the wafer. This is a mechanism for adsorbing a wafer by a differential pressure from the atmospheric pressure (see, for example, Patent Document 1).

  In the ceramic heater having the vacuum suction mechanism as described above, when the wafer is placed on the placement surface and held at a high temperature, the wafer temperature in the vicinity of the opening on the placement surface tends to locally decrease. This is presumed to be because the radiant heat transfer from the heater is smaller than the surrounding area due to the presence of the ventilation path. Due to such a local temperature drop in the vicinity of the opening, it is difficult to achieve uniform temperature over the entire mounting surface, and as a result, there is a problem that the entire wafer cannot be heated uniformly.

  The above problem may occur not only in a ceramic heater having a vacuum suction mechanism, but also in a ceramic heater having a ventilation path and an opening for supplying gas from the mounting surface toward the back surface of the wafer (for example, Patent Document 2). . That is, in Patent Document 2, as a ventilation path, a porous body is filled in a concave portion provided on the opposite side of the mounting surface of the ceramic substrate, and pores penetrating between the mounting surface and the bottom surface of the concave portion are provided. Although a configuration is disclosed, the above problem can occur even in such a configuration.

JP 2006-287213 A JP2013-232641A

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a local object on a mounting surface during heating in an object mounting member having a ventilation path communicating with the outside through an opening. The object is to provide an object mounting member capable of suppressing temperature drop and achieving uniform temperature.

The object mounting member of the present invention includes a base having a mounting surface on which the object is mounted;
A ventilation path that is provided inside the base body and communicates with the outside through an opening formed in the mounting surface;
An object mounting member having a heater provided inside the base or below the back surface of the base opposite to the mounting surface,
In the ventilation path, a breathable member having air permeability at a position opposite to the object when the object is placed on the placement surface, and at a position closer to the placement surface than the heater. Is at least partially disposed.

  The object mounting member of the present invention is arranged on the mounting surface by disposing at least a part of the breathable member having air permeability at the above position of the ventilation path as compared with the case where there is no such breathable member. A local decrease in the temperature of the object immediately above the formed opening is suppressed. This is because the air-permeable member reduces the flow velocity of air around the opening, reduces the heat absorption due to convective heat transfer, and suppresses the local temperature drop of the object. Therefore, it is possible to achieve a uniform temperature over the entire mounting surface and to heat the object evenly. Further, since it is a breathable member, the breathability of the ventilation path is maintained, and it is possible to evacuate the object to be adsorbed or to supply gas to the back surface (mounting surface side) of the object.

  Moreover, in the object mounting member of the present invention, it is preferable that the upper peripheral edge position of the breathable member is disposed at the same height position as the peripheral edge portion of the opening on the mounting surface. In this way, when the peripheral portion of the opening and the breathable member are at the same height position on the placement surface, that is, flush with each other, particle accumulation does not occur, so that it is possible to prevent adverse effects on the target object due to particles. it can.

  Furthermore, in the object mounting member of the present invention, it is possible to provide a plurality of the ventilation paths in the base, and in this case, it is preferable that the breathable member is disposed in at least a part of the plurality of ventilation paths. In order to further improve the heat uniformity, it is preferable to dispose a breathable member in all the ventilation paths.

  Furthermore, in the object mounting member of the present invention, at least one of the air-permeable members may be provided with a through-hole that communicates the ventilation path with the outside. The breathable member can ensure air permeability more reliably by communicating with the outside through the through hole.

The top view of the ceramic heater which concerns on embodiment of this invention. Sectional drawing along the AA of the ceramic heater shown in FIG. The perspective view which shows an example of the air permeable member which has a through-hole. The schematic cross section which shows the circumference | surroundings of the ventilation path | route of the example using the aggregate | assembly of a granular material as a breathable member.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments.

  FIG. 1 is a top view of a ceramic heater (object placing member) 10 according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA of FIG. A ceramic heater 10 shown in FIGS. 1 and 2 includes a disk-shaped substrate 12 for attracting and holding a wafer (object) W on the upper surface side (mounting surface side). The upper surface of the base 12 includes a plurality of pin-shaped convex portions 14 and a substantially annular annular convex portion 16 extending along the outer peripheral edge of the base 12 so as to surround the plurality of convex portions 14. ing. In FIG. 1, components such as the convex portion 14 and the annular convex portion 16 are deformed for clarification of the configuration, and in addition to the aspect ratio in the cross-sectional view of each component, the ratio of the width or height to the interval between them. Etc. are different from the actual.

  The plurality of convex portions 14 are arranged concentrically with the center of the base body 12 as a center at a predetermined interval in the circumferential direction and the radial direction. The plurality of convex portions 14 are regularly arranged in other forms such as a triangular lattice shape and a square lattice shape, and are locally irregular so that a difference in density is locally produced in the circumferential direction or the radial direction. May be arranged. The interval or pitch of the convex portions 14 is designed to be, for example, 20 [mm] or less, preferably 12 [mm] or less, and more preferably 8 [mm] or less. The protruding amount of the convex portion 14 from the upper surface of the base body 12 is designed to be included in the range of, for example, 5 to 500 [μm].

  The convex portion 14 has a columnar shape such as a columnar shape or a prismatic shape, a frustum shape such as a truncated cone shape or a truncated pyramid shape, a columnar shape with a step such that the upper cross-sectional area is smaller than the lower portion, or a frustum shape. It is formed into a shape. The diameter of the upper end portion (contact portion with the wafer W) of the convex portion 14 is designed to be 3.0 [mm] or less. The surface roughness Ra of the upper end portion (contact portion with the wafer W) of the convex portion 14 is designed to be included in the range of 0.01 to 2.0 [μm].

  The annular convex portion 16 may be formed so that the upper end thereof is at the same height as the upper end of the convex portion 14 or may be formed at a position lower than the upper end of the convex portion 14. The cross-sectional shape of the annular convex portion 16 along the radial direction of the base 12 may be various shapes such as a rectangular shape, a trapezoidal shape, a semicircular shape, or a semielliptical shape.

  Six through holes 18 are formed in the base 12, and the wafer W adsorbed on the mounting surface of the substrate 12 is separated from the mounting surface in the through holes 18. A lift pin (not shown) that can protrude upward is inserted. The six through holes 18 are arranged so as to have six-fold rotational symmetry with respect to the center of the base 12.

  A heating resistor 13 is provided as a heater inside the substrate 12, and the wafer W is heated by this heater. As a heater, the form which is provided under the back surface of a base | substrate and arrange | positions a heating means (for example, lamp | ramp etc.) in the position away from the back surface of the base | substrate may be sufficient.

  Furthermore, six openings 20 are formed in the base 12, and each opening 20 communicates with a ventilation path 22 formed in the base 12. In other words, the ventilation path 22 communicates with the outside through the opening 20. The six openings 20 are arranged so as to have six-fold rotational symmetry with respect to the center of the base 12. The end of the ventilation path 22 on the opposite side of the opening 20 is connected to a vacuum suction device (not shown). By operating this vacuum suction device, a negative gap is placed between the mounting surface and the wafer W. A pressure is generated, and the wafer W is attracted and held by the differential pressure from the atmospheric pressure. Further, instead of the vacuum suction device, it may be connected to a gas supply device. By operating the gas supply device, the wafer W is transferred by heat transfer via the gas supplied between the mounting surface and the wafer W. Heated.

  An air permeable member 24 having air permeability is disposed in the vicinity of the opening 20 of the air passage 22 on the mounting surface side from the heater 13. As described above, by arranging the air permeable member 24 in the air passage 22, a local decrease in the temperature of the wafer W immediately above the opening 20 is suppressed as compared with the case where there is no air permeable member 24. . Further, since the air permeable member 24 has air permeability, even if it is disposed in the air passage 22, it does not affect the vacuum suction of the wafer W.

  The upper peripheral position of the air-permeable member 24 is preferably disposed at the same height position as the peripheral part of the opening 20 on the mounting surface of the base 12. When the peripheral portion of the opening and the air permeable member are at the same height position on the mounting surface, that is, flush with each other, particle accumulation does not occur, so that it is possible to prevent adverse effects of the particles on the target object.

  In addition, the breathable member 24 is indirectly heated through the base 12 existing around the breathable member 24, and infrared rays are emitted from the end of the heated breathable member 24, whereby the breathable member 24. As a result of heating the wafer W placed immediately above the substrate, a local temperature drop of the wafer W can be suppressed.

  In order to prevent the breathable member 24 from moving due to vacuum suction, it is preferable to form a protrusion or the like on the inner wall of the vent path 22 to lock the breathable member 24. In addition, as a method for fixing the air permeable member 24 to the air passage 22, a method for press-fitting the air permeable member 24 or a method for bonding the air permeable member 24 to the air passage 22 using a heat-resistant adhesive is also employed. can do.

  The air-permeable member 24 is not particularly limited as long as it has air-permeability, for example, a member made of a porous body, a member provided with one or a plurality of through-holes for communicating the air passage 22 and the outside, Examples include aggregates of granular materials.

  As an example of a member provided with one or a plurality of through holes that allow the ventilation path 22 to communicate with the outside, a form in which four through holes are provided is shown in FIG. The air-permeable member 24 shown in FIG. 3 has a cylindrical shape, and four through holes 25 penetrating in the longitudinal direction are formed. When the air-permeable member 24 is inserted in the vicinity of the opening of the air passage 22, the air passage 22 and the outside communicate with each other through the four through holes 25, and air permeability can be ensured.

  Examples of aggregates of granular materials include, for example, aggregates of semi-lux beads, and an example is shown in FIG. In the example shown in FIG. 4, a plurality of ceramic beads 26 are filled in the ventilation path 22 near the opening 20. Further, a partition wall 28 having a through hole smaller than the diameter of the ceramic bead 26 is formed in the ventilation path 22 so that the ceramic bead 26 is not sucked during vacuum suction. Thus, even when a plurality of ceramic beads 26 are filled, there is a gap between adjacent ceramic beads 26, so that the air permeability of the ventilation path 22 can be ensured.

  The material of the air permeable member 24 is preferably a material having a high emissivity without being deformed in the temperature range to be used. This is because by using the breathable member 24 as such a material, a local decrease in the temperature of the wafer W is further suppressed by radiant heat transfer. Examples of the material having a high emissivity include ceramics and graphite. Among these, alumina, silica, oxides containing these, machinable ceramics, and silicon carbide are preferably used.

  In particular, when the above-described oxide or silicon carbide is used for the breathable member 24, the breathable member 24 is more preferably a porous body, and the porosity of the porous body is 20% or more and 60% or less. Is preferred. As the porous oxide body, a commercially available alumina porous body or a porous body made only of alumina having a large particle diameter can be suitably used. For machinable ceramics, commercially available macor (Ishihara Chemical Co., Ltd.) and Photovale (Ferrotec Ceramics Co., Ltd.) can be suitably used. In addition, for the air-permeable member 24, alumina glass beads or ceramic beads having a diameter of 500 μm or more can be suitably used.

  In addition, it is preferable that the radiation rate of the air permeable member 24 is 0.4 or more in the temperature range to be used, and it is more preferable that it is 0.7 or more. As the emissivity of the air permeable member 24 increases, the amount of radiant heat from the air permeable member 24 increases, and the local temperature drop of the wafer W placed above the opening 20 can be suppressed.

  The ratio (L / D) of the height (L) of the breathable member to the diameter (D) of the breathable member is 0.1 to 10 from the viewpoint of gas permeability and ease of arrangement of the breathable member. It is preferable. If L / D is smaller than 0.1, the air-permeable member becomes excessively thin, and it is difficult to stably arrange the air-permeable path. On the other hand, if L / D is greater than 10, the gas permeability of the air-permeable member becomes excessively small, which hinders evacuation and gas supply.

  In the case where a plurality of ventilation paths are provided in the base, it is preferable that the breathable member is disposed in at least a part of the plurality of ventilation paths. It is preferable to dispose a gas permeable member.

  In the embodiment shown in FIGS. 1 and 2 above, the ventilation path is connected to the vacuum suction device and the ventilation path is evacuated, but the present invention is not limited to any embodiment, and the ventilation path It is good also as a form which makes it a gas supply path which supplies gas to the back surface of a wafer. In the case of this form, the gas passage direction in the air permeable member is opposite to that shown in FIGS. 1 and 2, but the air permeable member suppresses a local temperature decrease and can achieve uniform heating of the wafer. it can.

  The ceramic heater of this embodiment can be manufactured as follows, for example. A ceramic heater having a vacuum suction mechanism or a gas supply path is produced according to a conventional method. There is no particular limitation on the method for producing such a ceramic heater. In addition, a breathable member is prepared that is disposed in the vicinity of the opening of the ventilation path (vacuum suction path or gas supply path) of the ceramic heater. And it can produce by inserting a ventilation member from opening of the ventilation path | route of the mounting surface of a ceramic heater.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

[Example 1]
A powder mixture composed of 97% by mass of aluminum nitride powder and 3% by mass of yttrium oxide powder was obtained, filled in a mold, and subjected to uniaxial pressure treatment. As a result, a first layer having a diameter of 350 mm and a thickness of 12 mm was formed.

  Next, as a heating resistor (heater), a molybdenum mesh (wire diameter: 0.1 mm, mesh size: 50 mesh) having a rotationally symmetrical shape and a diameter of 300 mm on the outermost periphery is formed on the first layer. Placed. Subsequently, the previously formed powder mixture was filled on the heating resistor to a predetermined thickness to form a second layer. Then, hot press firing was performed at a pressure of 10 MPa at a firing temperature of 1800 ° C. and a firing time of 2 hours to obtain a ceramic sintered body (substrate) having a diameter of 350 mm and a thickness of 25 mm. Thereafter, a through-hole having a diameter of 3 mm was formed from the upper surface to the lower surface of the ceramic sintered body so as to have 6-fold rotational symmetry with respect to the center as a ventilation path for vacuum suction. Furthermore, a large number of convex portions (height: 0.1 mm, diameter: 1.0 mm) and annular convex portions (diameter: 298 mm: height: 0.1 mm, width: 1) arranged in the form of dots by sandblasting 0.5 mm).

  Next, a breathable member (a cylindrical shape with a diameter of 3 mm and a height of 5 mm) made of a ceramic porous body (porosity 60%) was embedded in the vent path formed as described above.

  A hole having a diameter of 8 mm was formed so as to reach the heating resistor from the back surface of the substrate, and a cylindrical nickel metal terminal having a diameter of 8 mm was silver brazed to the exposed heating resistor to form a terminal.

(Evaluation results)
A blackened dummy wafer was placed on the mounting surface of the produced ceramic heater, electric power was supplied to the terminals to raise the temperature of the ceramic heater, and the temperature of the dummy wafer surface was measured with an IR camera. The power supplied to the terminals was the same for 15 minutes from the time when the surface temperature of the dummy wafer reached 500 ° C. Thereafter, the temperature distribution of the dummy wafer was measured.

  It was found that the temperature difference between the maximum temperature and the minimum temperature in the region near the opening of the ventilation path was as small as 0.2 ° C., and the thermal uniformity of the ceramic heater was good.

[Example 2]
A ceramic heater was used in the same manner as in Example 1 except that an alumina protective tube (diameter: 3 mm, height: 5 mm) provided with four through-holes having a diameter of 0.13 mm was used as the breathable member. It produced and evaluated similarly to Example 1.

(Evaluation results)
It was found that the temperature difference between the maximum temperature and the minimum temperature in the region near the opening of the ventilation path was as small as 0.4 ° C., and the thermal uniformity of the ceramic heater was good.

[Comparative Example 1]
A ceramic heater was produced in the same manner as in Example 1 except that no breathable member was used, and evaluated in the same manner as in Example 1.

(Evaluation results)
The temperature difference between the maximum temperature and the minimum temperature in the region near the opening of the ventilation path was as large as 1.4 ° C., and the thermal uniformity of the ceramic heater was insufficient.

10 Ceramic heater 12 Base 13 Heating resistor (heater)
14 convex portion 16 annular convex portion 18 through hole 20 opening 22 vent path 24 breathable member

Claims (4)

A substrate having a mounting surface on which an object is mounted;
A ventilation path that is provided inside the base body and communicates with the outside through an opening formed in the mounting surface;
An object mounting member having a heater provided inside the base or below the back surface of the base opposite to the mounting surface,
In the ventilation path, a breathable member having air permeability at a position opposite to the object when the object is placed on the placement surface, and at a position closer to the placement surface than the heater. At least a part of the object placement member is arranged.   2. The object mounting member according to claim 1, wherein the upper peripheral edge position of the breathable member is arranged at the same height position as the peripheral edge portion of the opening on the mounting surface. Material placement member.   3. The object mounting member according to claim 1, wherein the base is provided with a plurality of the ventilation paths, and the breathable member is disposed in at least a part of the plurality of ventilation paths. An object mounting member characterized by the above.   The object mounting member according to any one of claims 1 to 3, wherein at least one of the air-permeable members is provided with a through-hole that communicates the ventilation path with the outside. An object placement member.