JP5971556B2 - Electrostatic chuck and electrostatic chuck module - Google Patents

Description

  The present invention relates to an electrostatic chuck used when processing a substrate such as a semiconductor wafer at a high temperature and an electrostatic chuck module including the electrostatic chuck.

  In semiconductor manufacturing processes such as ion implantation, CVD, and sputtering, the wafer is processed while the temperature of the semiconductor wafer to be processed is kept high.

  In such a process, an electrostatic chuck having a heating function for fixing the posture of the wafer being processed and increasing the wafer temperature is used.

  For example, as an example of an electrostatic chuck having a heating function, a configuration described in Patent Document 1 is used.

  The electrostatic chuck described in Patent Document 1 has a conductive heat generating layer formed on one surface of a support base material and an electrostatic adsorption electrode formed on the other surface. An electrostatic chuck having a configuration in which an insulating layer is formed so as to cover the heat generating layer, the electrostatic adsorption electrode, and the support base.

Japanese Patent No. 4811608

  In order to control the temperature of the electrostatic chuck, this type of electrostatic chuck is brought into contact with the base member in a state where the tip of the thermocouple is pressed. Electric charges accumulate on the substrate surface due to the voltage applied to the electrostatic adsorption electrode during wafer adsorption using an electrostatic chuck, but this accumulated charge flows out to the ground side through a thermocouple in contact with the substrate. It is configured.

  However, since the contact between the base material and the thermocouple is made by pressing the tip of the thermocouple against the base material, the contact tends to become unstable. In this case, it is difficult for the electric charge accumulated in the base material to flow out to the ground side through the thermocouple. When checking whether the wafer is normally attracted by the electrostatic chuck, in the case of a bipolar electrostatic chuck, the capacitance between the electrodes is measured, and the wafer support state is determined based on this value. It has been done to detect. On the other hand, in the case of a unipolar electrostatic chuck, the electrostatic capacity between the electrode adsorbing the wafer and the wafer is measured to detect the support state of the wafer.

  When performing such detection, if the charge accumulated on the base material does not flow to the ground side and remains as a residual charge on the base material, the capacitance value is accurately measured under the influence of this charge. There was a problem that it could not be done. In addition, the base material is charged up under the influence of the residual charge, and there is also a problem that the chucking force of the electrostatic chuck becomes unstable.

  Accordingly, the main object of the present invention is to provide an electrostatic chuck having a configuration capable of reliably removing residual charges accumulated on a substrate and an electrostatic chuck module having the electrostatic chuck. .

  The electrostatic chuck of the present invention is an electrostatic chuck in which a heat generating member is disposed on one surface side of a conductive substrate, and an electrode for electrostatic adsorption is disposed on the other surface side of the substrate. Except for one place or a plurality of places on the surface of the material, at least a part is fixed to the insulating layer covering the heat generating member, the electrode and the base material, and the surface of the base material not covered with the insulating layer. And a conductive member whose other part is electrically grounded.

  By using such a configuration, the grounding of the substrate can be reliably performed.

  The electrostatic chuck module of the present invention is an electrostatic chuck module including the above-described electrostatic chuck, and is electrically grounded, and a support base that supports the lower surface of the insulating layer; and the electrostatic chuck is connected to the electrode. A through-hole penetrating through the surface of the base material not covered with the insulating layer and the insulating layer covering the surface of the base material on the heating member side, A conductive member inserted into the through-hole, having one end fixed to the surface of the substrate and the other end electrically connected to the support base.

  With such a configuration, it is possible to both attach the electrostatic chuck to the support base and electrically ground the substrate using the conductive member.

  Moreover, the said electroconductive member is a volt | bolt provided with the head larger than the said through-hole in one end, Comprising: You may employ | adopt the structure by which the said head is electrically connected with the said base material.

  With such a configuration, attachment of the electrostatic chuck to the support base and electrical grounding of the base material can be performed more reliably.

  Furthermore, a washer may be disposed between the head and the base material.

  With such a configuration, it is possible to prevent damage to the base material accompanying tightening of the bolt.

  In addition, the washer may be made of carbon.

  Carbon washers are relatively soft. Therefore, by using such a washer, even if the base material and the bolt are thermally deformed, the deformation can be absorbed by the washer portion, and the electrical connection between both members can be maintained. In addition, since the carbon washer is less expensive than other members, there is an advantage in terms of cost.

  The grounding of the base material can be performed reliably, and the capacitance can be measured accurately. Further, by fixing the substrate to the ground potential, the instability of the electrostatic chuck attracting force due to the charge-up of the substrate can be eliminated.

It is sectional drawing of the electrostatic chuck which concerns on this invention. (A) A state where the conductive member is fixed to the side surface of the substrate is shown. (B) A state in which the conductive member is fixed to the lower surface of the base material is shown. (C) A state in which the conductive member is fixed to the upper surface of the base material is shown. It is sectional drawing of the electrostatic chuck module which concerns on this invention. It is sectional drawing showing a mode when a conductive volt | bolt is removed from the structure of FIG. It is sectional drawing showing the other example of the electrostatic chuck module which concerns on this invention.

  Hereinafter, configurations of an electrostatic chuck and an electrostatic chuck module according to the present invention will be described with reference to the drawings. In the following description, the surface of each part on the side on which the wafer is placed is called the upper surface, and the surface on the opposite side is called the lower surface.

  1A to 1C are sectional views of an electrostatic chuck C of the present invention on which a wafer 3 as a processing object is placed on the upper surface.

  In the electrostatic chuck C, the lower surface of the wafer 3 is electrostatically mounted on the surface side on which the substrate 1 (for example, a conductive member made of a graphite-containing substance) and the wafer 3 (for example, a semiconductor wafer, silicon carbide) are placed. An electrode 2 for adsorption is provided, and a power source (not shown) is connected to the electrode 2 so that a voltage is applied through an electric line.

  On the other hand, a heat generating member 4 for heating the wafer 2 is disposed on the surface side of the substrate 1 opposite to the surface on which the electrode 2 is disposed. The heat generating member 4 is a member that generates heat upon receiving power from the outside of the electrostatic chuck C, and is used for temperature control of the wafer 3 placed on the upper surface of the electrostatic chuck C. Regarding the temperature control, the heating member 4 is adjusted so that the temperature of the wafer 3 becomes a desired temperature according to a measurement result with a thermocouple (not shown) or a measurement result with a radiation thermometer provided above the wafer 3. This is done by controlling the output.

  In the electrostatic chuck C of the present invention, the insulating layer 5 (for example, made of a boron nitride-containing material) is formed so as to cover the periphery of the substrate 1, the electrode 2, and the heat generating member 4 except for one or more locations of the substrate 1. Layer). In the example of FIGS. 1A to 1C, a part of the substrate 1 is not covered with the insulating layer 5 in the exposed portion 6 illustrated. In FIG. 1 and FIGS. 2 to 4 to be described later, the configuration in which the insulating layer 4 covers the periphery of each part except for one place on the surface of the base material 1 is depicted. A configuration in which a plurality of locations that are not provided may be provided.

  In the configuration depicted in FIGS. 1A to 1C, one end of the conductive member 7 is fixed to the substrate 1 through the exposed portion 6. For example, this fixing may be performed by using a conductive bolt as the conductive member 7 and screwing it to the base material 1. Of course, as long as the electrical connection between both members can be sufficiently secured, other methods may be used without being limited to the above-described method. For example, the conductive member 7 may be embedded in the base material 1. The fixing structure described here does not mean that the relative positional relationship between the members does not change at all. A structure in which the electrical connection between the members can be sufficiently secured, and when the electrostatic chuck C is heated, each member is thermally deformed, and the relative positional relationship between the members is slightly changed. included.

  The conductive member 7 is electrically grounded at a portion different from the portion fixed to the base material 1. By using such a configuration, it is possible to reliably remove the residual charges accumulated in the substrate 1. As a material of the conductive member 7, it is conceivable to use a high melting point material such as tungsten, tantalum, or molybdenum in consideration of the high temperature of the electrostatic chuck C.

  In the configuration of FIG. 1A, the exposed portion 6 is formed on the side surface of the electrostatic chuck C. However, even if it is formed at a position where the conductive member 7 can be easily introduced in order to ground the substrate 1. Good. Specifically, the exposed portion 6 may be provided on the lower surface side of the electrostatic chuck C as shown in FIG. 1B, or the upper surface side of the electrostatic chuck C as shown in FIG. An exposed portion 6 may be provided on the surface.

  Further, as described above, the exposed portion 6 does not need to be provided at one place, but is provided at a plurality of locations, and the conductive member 7 is introduced through each exposed portion 6 and fixed to the substrate 1. You may make it do. If it is set as such a structure, the electrical grounding of the base material 1 can be performed more reliably.

  Moreover, you may use the thermocouple conventionally used as the electroconductive member 7 of this invention. In this case, it is conceivable to fix the thermocouple to the surface of the substrate 1 by processing a part of the thermocouple or combining it with another member. Of course, the conductive member 7 may be provided separately from the thermocouple and fixed to the surface of the substrate 1. In this case, the exposed portion 6 for introducing the thermocouple and the conductive member 7 may be shared, or may be provided separately for each member.

  2 and 3 illustrate the configuration of an electrostatic chuck module including the electrostatic chuck C of the present invention. For example, this module is used when the electrostatic chuck C is fixed and used at a predetermined place. In this example, a conductive bolt 10 is used as the conductive member 7. 2 is a cross-sectional view showing a state in which the electrostatic chuck is fixed to the support base 13 with the conductive bolt 10, and FIG. 3 is a state when the conductive bolt 10 is removed from the configuration depicted in FIG. It is sectional drawing showing.

  The support base 13 that supports the electrostatic chuck is a conductive member and is electrically grounded. Further, in this example, the through hole 15 is formed in the exposed portion 6 described in the example of FIG. 1, and the through hole 15 is formed so as to penetrate at least the base material 1 and the insulating layer 4 in one direction. Yes.

  The conductive bolt 10 includes a head 14, and at least the head 14 is electrically connected to the base material 1. The diameter of the head 14 is larger than the diameter of the through-hole 15, and other rod-like portions excluding the head 14 are inserted into the through-hole 15, and the tip portion is screwed to the support base 13. By using such a configuration, it is possible not only to electrically ground the base material 1 but also to fix the electrostatic chuck to the support base 13.

  A first washer 11 and a second washer 12 as illustrated in FIG. 2 are provided between the head 14 of the conductive bolt 10 and the base material 1. These washers are made of a conductive material. More specifically, the first washer 11 is made of carbon, and the second washer 12 is made of tantalum.

  By providing these washers, it is possible to prevent the base material 1 from being damaged due to the tightening of the conductive bolt 10.

  Further, when the conductive bolt 10 is made of a high melting point material and the base material 1 is made of a carbon-containing material having a significantly different coefficient of thermal expansion, both members are heated by heating of the electrostatic chuck. It is conceivable that the member is deformed and contact between the members is not sufficiently made. In order to prevent such contact failure, it is conceivable to provide a first washer made of a carbon material, and to absorb distortion caused by thermal deformation of both members with this washer. Thereby, it becomes possible to maintain the electrical connection between both members.

  Furthermore, the load applied to the first washer 11 made of the carbon material by providing the second washer 12 made of the high melting point material between the first washer 11 and the head 14 of the conductive bolt 10. Can be reduced. Thereby, damage to the first washer 11 having relatively low strength can be prevented.

<Other variations>
The electrostatic chuck module is provided with a heat shield shield 8 for improving the utilization efficiency of the heat generated by the heat generating member 4, and this heat shield shield 8 is attached to the support base 13 as necessary. It should be configured as follows.

  In the example of FIGS. 2 and 3, the tip of the conductive bolt 10 is screwed to the support base 13, but the present invention is not necessarily limited to such a configuration. For example, as in the example depicted in FIG. 4, the above-described through hole 15 is formed so as to also penetrate the support base 13, and a conductive bolt is formed using a nut 16 on the lower surface side of the support base 13. You may comprise so that the front-end | tip part of 10 may be fixed. On the other hand, if both ends of the conductive bolt 10 are fixed, it is difficult to release stress between the members when thermal deformation occurs. For this reason, for example, a wide leaf spring may be extended from the support base 13 and may be brought into surface contact along the shape of the end of the conductive bolt 10 on the support base 13 side. . With such a configuration, the electrical connection with the support base 13 can be sufficiently maintained while releasing stress between the members.

  The diameter of the through-hole 15 shown in FIGS. 2 to 4 is slightly larger than the diameter of the conductive bolt inserted into the through-hole 15 in consideration of thermal deformation of the conductive bolt 10 and the base material 1. It is conceivable to make it larger.

  The insulating layer 4 described in the above example may be composed of one layer, or may be composed of a plurality of layers stacked in multiple layers. Specifically, a pyrolytic boron nitride (PBN) layer (first insulating layer) is CVD coated on a conductive graphite substrate, and a conductive layer comprising a pyrolytic graphite (PG) layer thereon. Coating. Then, this conductive PG layer is machined to form electrodes and heating element patterns, and then pyrolysis with carbon mixed for resistance adjustment to cover the pyrolytic graphite (PG) layer. Coating a boron nitride (PBN) layer (second insulating layer). In this way, the insulating layer 4 may have a two-layer structure.

  Further, the shape of the head 14 of the conductive bolt 10 may be any shape such as a circle, a hexagon and the like. As long as the head part 14 is larger than the diameter of the through-hole 15, what kind of thing may be sufficient. Moreover, the shape of the through-hole 15 may be any shape such as a circle or a rectangle.

  Of course, various improvements and modifications other than those described above may be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Base material 2 ... Electrode 3 ... Wafer 4 ... Heat generating member 5 ... Insulating layer 6 ... Exposed part 7 ... Conductive member C ... Electrostatic chuck

Claims (5)

An electrostatic chuck in which a heat generating member is disposed on one surface side of a conductive substrate, and an electrode for electrostatic adsorption is disposed on the other surface side of the substrate,
Except for one place or a plurality of places on the surface of the base material , an insulating layer covering the heat generating member, the electrode and the base material
An electrostatic chuck comprising: a conductive member that is at least partially fixed to a surface of the base material that is not covered with the insulating layer, and the other part is electrically grounded. An electrostatic chuck module comprising the electrostatic chuck according to claim 1,
A support base that is electrically grounded and supports the lower surface of the insulating layer;
When the electrostatic chuck is viewed from the surface on which the electrode is disposed, at least the surface of the base material that is not covered with the insulating layer and the insulating layer that covers the surface of the base material on the heating member side A through hole penetrating through,
An electrostatic chuck module, comprising: a conductive member inserted into the through hole, having one end fixed to the surface of the base material and the other end electrically connected to the support base. The conductive member is a bolt having a head larger than the through hole at one end,
The electrostatic chuck module according to claim 2, wherein the head is electrically connected to the base material.   The electrostatic chuck module according to claim 3, wherein a washer is disposed between the head and the base material. The electrostatic chuck module according to claim 4, wherein the washer is made of carbon.

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