JP2012059837A - Shaft and support device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shaft capable of reducing deterioration of thermal uniformity of surface temperature.SOLUTION: A shaft 100 has, on a surface connected to a heater plate, a plurality of first through holes 110 for inserting a conductor, and a plurality of second through holes 120 for inserting a fixing member for mechanically fixing the heater plate and the shaft 100. The first through holes 110 are spaced apart from each other on a first circular ring around a midportion of the surface connected to the heater plate, and the second through holes 120 are spaced apart from each other on a second circular ring coaxial with the first circular ring. Each of the first through holes 110 and each of the second through holes 120 are disposed so that the center of the first through hole 110 and the center of the second through hole 120 are not aligned in a straight line when the outside of the shaft is viewed from the centers of the first circular ring and the second circular ring.

Description

  The present invention relates to a shaft and a support device that support an object to be processed such as a semiconductor wafer.

  2. Description of the Related Art Conventionally, as a supporting device for supporting an object to be processed such as a semiconductor wafer, a heater plate in which a heater and a high-frequency electrode are embedded and a shaft for supporting the heater plate are provided, and the heater plate and the shaft are fixed with screws. A supporting device configured as described above is known (for example, Patent Document 1).

  In the heater plate, the surface on which the semiconductor wafer is placed is heated by a heater or a high-frequency electrode during the process for the semiconductor wafer. In this case, since the heater plate is in contact with the shaft, heat loss is caused that heat is transferred through the shaft, and as a result, the surface temperature of the surface on which the semiconductor wafer is placed is In the range where the shaft is attached to the opposite surface, the temperature distribution gradually decreases. In the process for the semiconductor wafer, it is preferable that the temperature distribution is low or high, but even if there is a heat loss, if the temperature distribution is gentle as described above, the heat loss is calculated in advance, and a known correction is made. By applying, it is possible to perform highly uniform processing.

JP 7-153706 A

  By the way, on the surface of the shaft facing the heater plate, a plurality of through holes for inserting conductors connected to terminals for supplying power to the heater and high frequency electrodes and a plurality of through holes for inserting the screws are used. Are provided at regular intervals on the ring.

Therefore, even in the range where the shaft is in contact with the heater plate, the heat loss is small in the range where the through hole exists. Therefore, depending on the arrangement of the plurality of through holes, there is a problem that the temperature difference between the portion with a large heat loss and the portion with a small heat loss increases, and the thermal uniformity of the surface temperature of the surface on which the semiconductor wafer is placed is lowered There is.

  An object of the present invention is to provide a shaft and a support device that can eliminate such inconvenience and can reduce a decrease in thermal uniformity of the surface temperature of the surface on which the semiconductor wafer is placed.

  In order to achieve such an object, the shaft of the present invention is a shaft that joins the heater plate on the surface of the heater plate having a heating resistor facing the surface on which the wafer is placed, and on the surface to be joined, A plurality of first through holes for inserting conductors connected to terminals for supplying power to at least the heating resistor; and a plurality of fixing members for mechanically fixing the heater plate and the shaft. And the plurality of first through holes are arranged on the first annular ring centered on the center of the surfaces to be joined with a space therebetween, and the plurality of second through holes Are arranged on a second annular ring that is concentric with the first annular ring and has a smaller or larger diameter than the first annular ring, and each of the plurality of first through holes, Each of the second through holes of The center of the first through hole and the center of the second through hole are arranged so as not to be aligned on a straight line when facing the outside of the shaft from the center of the first and second annular rings. It is characterized by being.

  In the support device of the present invention, the shaft has a plurality of first through holes for inserting a conductor connected to the terminal on a surface facing the heater plate, with a space on the first annular ring. A plurality of second through holes for inserting the fixing member are disposed on the second annular ring at intervals, the second annular ring being concentric with the first annular ring, and The first annular ring is arranged so as to have a smaller diameter or a larger diameter.

  And when each of the plurality of first through holes and each of the plurality of second through holes faces the outside of the shaft from the center of the first ring and the second ring, It arrange | positions so that the center of a 1st through-hole and the center of the said 2nd through-hole may not line up on a straight line.

  Therefore, according to the support device of the present invention, when measuring the temperature distribution of the surface on which the semiconductor wafer is placed in the radial direction from the center of the first and second annular rings, the omnidirectional from the center. As the center of the first through hole and the center of the second through hole are aligned on a straight line, a portion with relatively little heat loss is generated even in the range where the shaft is in contact. And the situation where the uniformity of the said temperature distribution falls significantly can be avoided.

  As a result, it is possible to reduce a decrease in thermal uniformity of the surface temperature of the surface on which the semiconductor wafer is placed.

  In the shaft of the present invention, the plurality of first through holes and the plurality of second through holes are arranged so as to have rotational symmetry with respect to the centers of the first annular ring and the second annular ring. Is preferred.

  According to the shaft having this configuration, when the temperature distribution of the surface on which the semiconductor wafer is placed in the radial direction from the center of the first and second annular rings is measured, all directions are faced from the center. At this time, it is possible to avoid a situation in which the uniformity of the temperature distribution is harmed by the fact that the portions with relatively little heat loss are concentrated in a certain direction.

  In the shaft of the present invention, the plurality of first through holes and the plurality of second through holes are between a pair of tangents of the first through hole starting from the center of the first annular ring and the pair of tangents. A pair of tangents and a pair of tangents of the second through hole starting from the center of the second annular ring, a first sector region surrounding the first through hole defined by an arc outside the shaft sandwiched between It is preferable that the second fan-shaped region surrounding the second through-hole defined by the outer arc of the shaft sandwiched between the second fan-shaped regions does not overlap.

  According to the shaft having this configuration, when the temperature distribution of the surface on which the semiconductor wafer is placed in the radial direction from the center of the first and second annular rings is measured, all directions are faced from the center. At this time, since the first through hole and the second through hole do not line up in a straight line, it is possible to avoid a situation in which heat loss occurs in a plurality of places in any orientation. A reduction in thermal uniformity of the surface temperature of the surface on which the semiconductor wafer is placed can be further reduced.

  The shaft of the present invention has a plurality of third through holes that constitute a passage for supplying purge gas to the surfaces to be joined, and the plurality of third through holes are connected to the first annular ring. The third through holes are concentrically arranged on the third annular ring having a smaller or larger diameter than the first annular ring or the second annular ring, and each of the plurality of third through holes is arranged on the third circle. When facing the outside of the shaft from the center of the ring, the center of the first through hole, the center of the second through hole, and the third through hole may be arranged so as not to be aligned on a straight line.

  According to the shaft having this configuration, even when a plurality of third through holes are provided as passages for supplying purge gas to the surfaces to be joined, the semiconductor wafer is mounted in the radial direction from the center of the third ring. When the temperature distribution of the surface to be placed is measured, the center of the first through hole, the center of the second through hole, and the center of the third through hole are in a straight line when facing all directions from the center. As a result, it is possible to avoid a situation in which a portion with relatively little heat loss is generated even in the range where the shaft is in contact, and the uniformity of the temperature distribution is greatly reduced.

  As a result, it is possible to reduce a decrease in thermal uniformity of the surface temperature of the surface on which the semiconductor wafer is placed.

  The support device of the present invention includes the shaft of the present invention, the heater plate, and the fixing member that mechanically fixes the shaft and the heater plate.

The top view which shows the shaft of this embodiment. Sectional drawing which shows the support apparatus in this embodiment. The top view which shows the modification of the shaft of this embodiment.

(Overall configuration of this embodiment)
As shown in FIG. 1, the shaft 100 is a first for inserting two heater terminals 212, an RF terminal 222, and a thermocouple terminal (not shown), which will be described later, at a joint surface with the heater plate 200, which will be described later. It has a through hole 110, a second through hole 120 for inserting a screw 230 described later, a third through hole 130 that forms a purge gas passage, and a substantially annular groove 140.

  Next, the overall image of the support device 1 of the present invention will be described with reference to FIG. In addition, in order to clarify the connection relation between the electrode inserted through the shaft 100 and the inside of the heater plate 200, the shaft 100 has a cross section taken along a line A1-A6 having a bend in FIG.

  Here, how the A1-A6 line is bent will be described with reference to FIG.

  First, A4 is the center point of the shaft 100 that is circular in plan view. Next, the specific second through hole 120 is A2, and the intersection of the extension line from A4 to A2 and the outer periphery of the shaft 100 is A1. Next, the first through hole 110 closest to the A2 is referred to as A3. Further, among the third through holes 130, the one away from A3 is referred to as A5. Furthermore, the intersection of the extension line from A4 to A5 and the outer periphery of the shaft 100 is defined as A6.

  The broken line drawn in order from the above A1, A2, A3, A4, A5, A6 is the A1-A6 line.

  As shown in FIG. 2, the support device 1 of this embodiment includes a shaft 100 and a heater plate 200, and holds the wafer 400 on the heater plate 200. The support device 1 is placed in a process chamber (not shown), and is placed in a process gas atmosphere corresponding to each process such as fluorine gas while holding the wafer 400. The process gas is supplied at a predetermined pressure into the chamber through a supply path (not shown).

The heater plate 200 is formed in a substantially disc shape from a ceramic made of AlN, SiC, Mg ₂ Al ₂ O ₄ , Al ₂ O ₃ or the like. The heater plate 200 may have a triangular plate shape, a square plate shape, or the like. Among the raw materials, AlN is preferable because it has high thermal conductivity among ceramics, and is excellent in heat uniformity. Further, by adding Y ₂ O ₃ , heat uniformity can be improved.

  A heater 210 is embedded in the heater plate 200 at a position close to a surface (hereinafter simply referred to as a bonding surface) where the heater plate 200 is bonded to the shaft 100. Further, the electrode 220 is embedded at a position close to the surface holding the wafer 400 facing the electrode 220.

  The heater 210 is a heating resistor, and is wound, for example, in a spiral shape, and generates Joule heat by flowing an electric current. At both ends of the heater 210, a substantially bottomed cylindrical heater terminal 212 is connected and fixed, for example, by brazing, at a substantially central portion of the joining surface of the heater plate 200. A rod-shaped Ni rod electrode 214 is connected and fixed to the cylindrical hole of the heater terminal 212 through the first through hole 110 by brazing. The pair of Ni rod electrodes 214 are respectively connected to a heater power source (not shown), and by operating them, the heater 210 can generate heat. The Ni rod electrode 214 is covered with a cylindrical insulating sleeve (alumina sleeve) to prevent discharge between terminals.

  The heater 210 is manufactured using a metal having excellent heat resistance and a small thermal expansion coefficient, or a metal having a thermal expansion coefficient close to that of the ceramic forming the heater plate 200 (for example, Mo, W, etc.). It is preferable. The heater terminal 212 is preferably manufactured using Kovar, Mo, or Ni as a raw material.

  The electrode 220 is an RF electrode used when plasma processing is performed on the wafer 400. Similarly to the heater terminal 212 used for the heater 210, the electrode 220 has the RF terminal 222 fixed thereto, and is connected to the Ni rod electrode 224 through the first through hole 110 in the cylindrical hole of the RF terminal 222. It is fixed. The Ni rod electrode 224 is also covered with a cylindrical insulating sleeve (alumina sleeve) in order to prevent discharge between terminals.

  Further, the heater 210 is provided with an insertion hole for inserting a thermocouple (not shown) through the first through hole 110 in order to measure the temperature of the wafer 400, and the thermocouple is connected and fixed. .

  In addition, the heater plate 200 may incorporate an ESC electrode.

The shaft 100 is formed in a substantially cylindrical shape by a ceramic made from AlN, SiC, Mg ₂ Al ₂ O ₄ , Al ₂ O ₃ or the like.

  In particular, AlN is preferable as a ceramic because of its high thermal conductivity and excellent thermal uniformity. That is, as shown in FIG. 1, when a power supply terminal is provided at the center of a disk-shaped heater plate 200, the center portion tends to have heat, and the temperature distribution may be higher as it goes to the periphery. On the other hand, when the raw material of the shaft 100 is AIN, the shaft 100 can release the heat accumulated in the central portion, so that the temperature distribution on the surface of the wafer 400 can be easily averaged.

  The shaft 100 is provided with a purge gas supply means (not shown) for supplying purge gas to the third through hole 130 that forms a purge gas passage along the axial direction on the opposite side of the joint surface.

  The shaft 100 is filled with a purge gas such as N 2 to the joint surface of the heater plate 200 through the third through hole 130 by the purge gas supply means.

  The type of purge gas may be Ar, He or the like as long as it does not affect the process.

  Further, a through hole 132 communicating with the third through hole 130 is provided from the bonding surface of the heater plate 200 to the surface holding the wafer 400, and evacuation is performed from the opposite side of the bonding surface of the shaft 100 through the third through hole 130. As a result, the wafer 400 can be fixed by suction.

  Note that the third through hole 130 may be configured to be branched in the middle, communicate with the groove portion 140 at the end on the joint surface side, and supply purge gas to the groove portion 140.

  The shaft 100 and the heater plate 200 are fastened by a screw (fixing member) 230 and a screw hole 232 provided with the heater plate with the second through hole 120 as a counterbore.

  In addition to the screws, the fixing member may be a mechanism that can mechanically fix the heater plate 200 and the shaft 100, such as a clamp.

  The screw 230 is made of metal or ceramic. In the case of a metal screw, in consideration of heat resistance and an expansion coefficient, those containing Inconel, Ni and Ti as main components are used. The torque for tightening the screw is preferably about 6 Nm for a hexagon socket head bolt with a nominal diameter of M5, and if it is 10 Nm or more, the screw part may be damaged.

  In addition, it is preferable to perform a surface polishing process such as lapping on the joining surface of the heater plate 200 and the joining surface of the shaft 100 to be fastened until the surface roughness Ra is 0.2 μm or less and the flatness is 2 μm.

  Further, a metal O-ring 500 is sandwiched between the joint surface of the heater plate 200 and the joint surface of the shaft 100. The O-ring 500 is preferably heat resistant stainless steel or inconel. Further, the surface of the O-ring 500 is preferably coated with gold or nickel of 20 μm or more. The O-ring 500 is designed to have a cross section larger than that of the groove portion 140, and it is preferable that the O-ring 500 is fastened with the screw so as to crush at least 50 μm.

  Further, as a method for controlling the air leak, a metal foil, a brazing material, an adhesive, or the like may be used. Further, the thickness of the metal foil is less than 1 μm, and it is difficult to produce the metal foil. If the thickness is 10 μm or more, a large fastening force is required to cause deformation, and there is a possibility of breakage of the threaded portion. This metal foil is elastically deformed and plastically deformed along the slight unevenness of the surface of each joint surface by the tightening torque of the screw 22, so that the degree of adhesion between the heater plate 200 and the shaft 100 is extremely high. Can do.

(Characteristic configuration of this embodiment)
A characteristic configuration of the present embodiment will be described with reference to FIG.

  As shown in FIG. 1, the shaft 100 includes a first through hole 110 through which a heater terminal 212, an RF terminal 222, and a thermocouple terminal (not shown) are inserted at a joint surface with the heater plate 200, a screw 230 has a second through hole 120 for inserting 230 and a third through hole 130 for forming a purge gas passage.

  The first through-holes 110 are provided at four locations on the joint surface with the heater plate 200, and the four first through-holes 110 are on the first annular ring concentric with the circle formed by the joint surface. Further, they are arranged at equal intervals with rotational symmetry.

  The second through holes 120 are provided at six locations on the joint surface with the heater plate 200, and the six second through holes 120 are concentric second rings surrounding the first ring. Above, they are arranged at equal intervals with rotational symmetry.

  Further, the third through holes 130 are provided at two locations on the joint surface with the heater plate 200, and the two third through holes 130 are concentric third rings surrounding the second ring. Above, they are arranged at equal intervals with rotational symmetry.

  That is, the first ring, the second ring, the third ring, and the circle formed by the joint surface are concentric circles. Further, in this embodiment, the first circle, the second circle, the third circle, and the circle formed by the joint surface have a large diameter in this order, but the first circle The diameters of the rings, the second ring, and the third ring may be in any order.

  When the first through hole 110, the second through hole 120, and the third through hole 130 are azimuth lines that start from the center of the concentric circle (A4 in FIG. 1) and go to the outside of the joint surface, 2 It arrange | positions so that the azimuth | direction line which passes the center part of the above through-hole may not generate | occur | produce. That is, when a cross section parallel to the axial direction of the shaft passing through the center of the concentric circle (A4 in FIG. 1) is considered, the central portion of the through hole other than the same type of through hole is the cross section regardless of the cross section taken at any angle. It is arranged so that it does not appear in.

  For example, as shown in FIG. 1, when considering a cross section passing through the center of a specific first through hole 110 (for example, A3 in FIG. 1) from the center of a concentric circle (A4 in FIG. 1), 2 The two first through holes 110 appear in the cross section at equal intervals from the center of the concentric circle, but the central portions of the second through hole 120 and the third through hole 130 do not appear in the cross section.

  Similarly, when a cross section passing through the center (for example, A2 in FIG. 1) of a specific second through hole 120 from the center of the concentric circle (A4 in FIG. 1) is considered, the two second through holes 120 are used. The central part of the first through hole 110 and the third through hole 130 do not appear in the cross section at equal intervals from the center of the concentric circle. Further, when a cross section passing through the center of the specific third through-hole 130 (for example, A5 in FIG. 1) from the center of the concentric circle (A4 in FIG. 1) is considered, the two third through-holes 130 Although the central portion appears in the cross section at equal intervals from the center of the concentric circle, the central portions of the first through hole 110 and the second through hole 120 do not appear in the cross section.

  As a more preferred modification of the present invention, the first through-hole 110, the second through-hole 120, and the third through-hole 130 are arranged in the radial direction of the joint surface starting from the center of the concentric circle (A4 in FIG. 1). When an azimuth line that goes to the outside is considered, the azimuth lines that pass through two or more through holes are not generated.

  Specifically, as shown in FIG. 3, a specific first through-hole 110 (for example, a first through-hole centered on A3 in FIG. 1) is sandwiched from the center of the concentric circle (A4 in FIG. 1). When considering the first sector region B1 surrounding the first through hole 110 defined by a pair of tangent lines and the arc of the joint surface between them, the second through hole 120 and the third through hole 130 are connected to the region. They are arranged so that they do not overlap.

  Similarly, a pair of tangent lines that sandwich a specific second through hole 120 (second through hole centered on A2 in FIG. 1) starting from the center of the concentric circle (A4 in FIG. 1) and the joint surface between them. When considering the second sector region B2 surrounding the second through hole 120 defined by the arc, the first through hole 110 and the third through hole 130 are arranged so as not to overlap with the region B2. Yes. Also, a pair of tangent lines sandwiching a specific third through hole 130 (second through hole centered on A5 in FIG. 1) starting from the center of the concentric circle (A4 in FIG. 1) and the joint surface between them When the third sector area B3 surrounding the third through hole 130 defined by the arc is considered, the first through hole 110 and the second through hole 120 are arranged so as not to overlap with the area B3. .

  That is, when a cross section parallel to the axial direction of the shaft passing through the center of the concentric circle (A4 in FIG. 1) is considered, a through hole other than the same type of through hole appears in the cross section regardless of the cross section taken at any angle. Is arranged so that there is no.

(Effect of this embodiment)
In the support device 1 having the above-described configuration, the shaft 100 is disposed on the joint surface with the heater plate 200 so that the plurality of first through holes 110 have rotational symmetry with a space on the first annular ring. The plurality of second through holes 120 are arranged on the second ring having a diameter larger than that of the first ring so as to have rotational symmetry, and the plurality of third through holes 130 are formed in the first ring. It arrange | positions so that it may have a rotational symmetry at intervals on the 3rd ring with a larger diameter than 2 rings.

  Therefore, when the temperature distribution on the surface of the heater plate 200 is measured, first, since the power supply terminal is provided in the center portion, heat tends to be held in the center portion, and the temperature distribution is higher in the center portion and lower as it goes to the periphery. Become. On the other hand, since the shaft 100 is in contact with the back surface of the central portion of the heater plate 200, the shaft 100 can release the heat accumulated in the central portion, so the temperature distribution on the surface of the heater plate 200 is averaged. Cheap.

  The first through-hole 110, the second through-hole 120, and the third through-hole 130 are obtained by considering an azimuth line that goes from the center of the concentric circle (A4 in FIG. 1) toward the radially outer side of the joint surface. It arrange | positions so that the azimuth | direction line which passes the center part of two or more through-holes may not generate | occur | produce.

  Therefore, according to the support device 1, when the temperature distribution on the surface of the heater plate 200 is measured, when facing all directions from the center of the surface, the center of the first through hole 110 and the second through hole 120. By aligning the center and the center of the third through hole 130 on a straight line, it is possible to prevent a portion having a relatively small heat loss at the contact surface between the shaft 100 and the heater plate from being locally generated, and A situation in which the uniformity is greatly reduced can be avoided.

  As a result, according to the support device 1 of the present embodiment, it is possible to reduce a decrease in thermal uniformity of the surface temperature of the surface on which the wafer 400 on the surface of the heater plate 200 is placed.

  Moreover, according to the modification of the support apparatus 1, the 1st through-hole 110, the 2nd through-hole 120, and the 3rd through-hole 130 start from the center (A4 of FIG. 1) of a concentric circle, and are the diameters of the said joint surface. When an azimuth line heading outward in the direction is considered, the azimuth lines passing through two or more through holes are not generated.

  Therefore, according to the support device 1 of the modified example, when the temperature distribution on the surface of the heater plate 200 is measured, the first through hole 110 and the second through hole 120 are viewed when facing all directions from the center of the surface. And the third through-hole 130 do not line up in a straight line when viewed from the center of the concentric circles, so that in any orientation, a portion with relatively little heat loss occurs at the contact surface between the shaft 100 and the heater plate at a plurality of locations. The situation where the uniformity of the temperature distribution is greatly reduced can be further avoided.

  DESCRIPTION OF SYMBOLS 1 ... Support apparatus, 100 ... Shaft, 110 ... 1st through-hole, 120 ... 2nd through-hole, 200 ... Heater plate, 210 ... Heater, 212 ... Heater terminal, 214 ... Ni rod electrode, 230 ... Screw, 400 ... Wafer , B1... First sector area, B2... Second sector area, B3.

Claims (5)

A shaft that joins the heater plate on the surface of the heater plate having the heating resistor facing the surface on which the wafer is placed,
A fixing member that mechanically fixes the plurality of first through holes for inserting a conductor connected to at least a terminal that supplies power to the heating resistor, the heater plate, and the shaft on the surfaces to be joined. A plurality of second through-holes for inserting
The plurality of first through holes are arranged on the first annular ring centered on the center of the surfaces to be joined, with an interval between them.
The plurality of second through holes are concentric with the first annular ring and are disposed on the second annular ring having a smaller diameter or larger diameter than the first annular ring, with a gap therebetween.
When each of the plurality of first through holes and each of the plurality of second through holes faces the outside of the shaft from the center of the first ring and the second ring, the first A shaft characterized by being arranged so that the center of the through hole and the center of the second through hole are not aligned on a straight line. The shaft according to claim 1, wherein
The shaft, wherein the plurality of first through holes and the plurality of second through holes are arranged so as to have rotational symmetry with respect to the centers of the first ring and the second ring. The shaft according to claim 1 or 2,
The plurality of first through holes and the plurality of second through holes are:
A first sector surrounding the first through hole defined by a pair of tangents of the first through hole starting from the center of the first annular ring and an arc outside the shaft sandwiched between the pair of tangents The second through hole defined by a region and a pair of tangents of the second through hole starting from the center of the second annular ring and an arc outside the shaft sandwiched between the pair of tangents 2. A shaft characterized by being arranged so as not to overlap with two fan-shaped regions. The shaft according to any one of claims 1 to 3,
In the joining surface, the joining surface has a plurality of third through holes that constitute a passage for supplying purge gas,
The plurality of third through holes are concentric with the first annular ring and disposed on the third annular ring having a smaller diameter or a larger diameter than the first annular ring or the second annular ring, with an interval between them.
Each of the plurality of third through holes, when facing the outside of the shaft from the center of the third annular ring, the center of the first through hole, the center of the second through hole, and the third through hole A shaft characterized by being arranged so that and do not line up in a straight line. The shaft according to any one of claims 1 to 3,
The heater plate;
A support device comprising: the fixing member that mechanically fixes the shaft and the heater plate.

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