JP2021190603A - Holding device - Google Patents

Abstract

To accurately measure the temperature of an object and reduce the temperature variation of the object.SOLUTION: A holding device according to the present disclosure includes an insulator 30 with front and back surfaces, a heater member having a heating element 41 arranged inside or on the back surface of the insulator 30, and a temperature measuring element arranged on the back side of the insulator 30, and holds an object on the surface of the insulator 30, and further includes a heat transfer portion 25 that is made of a material having higher thermal conductivity than the material forming the insulator 30, and is arranged from the vicinity of the temperature measuring element in the insulator 30 toward the surface side of the insulator 30.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a holding device.

For example, an electrostatic chuck is used as a holding device for holding a wafer when manufacturing a semiconductor. The electrostatic chuck includes a ceramic member having a suction surface and a chuck electrode provided inside the ceramic member, and utilizes the electrostatic attraction generated by applying a voltage to the chuck electrode. The wafer is sucked and held on the suction surface of the ceramic member.

If the temperature of the wafer held on the suction surface of the electrostatic chuck does not reach a desired temperature, the accuracy of each process (film formation, etching, etc.) on the wafer may decrease. Therefore, the electrostatic chuck needs to control the temperature of the wafer, and for example, a plurality of heater electrodes are provided inside the ceramic member. When a voltage is applied to each heater electrode, the ceramic member is heated by the heat generated by each heater electrode, whereby the temperature of the suction surface of the ceramic member (the temperature of the wafer held on the suction surface) becomes a desired temperature. It is controlled to approach.

For example, in the electrostatic chuck 1 described in FIG. 2 of JP-A-2016-72477 (Patent Document 1 below), a plurality of heaters 41 are arranged inside the main body substrate 11. The heater 41 is arranged inside the main body substrate 11 below the adsorption electrode 21. Since a temperature sensor 341 for measuring the temperature of the heater 41 is provided directly under the heater 41, the temperature of the heater 41 is measured by the temperature sensor 341, and the temperature of the substrate surface 111 is measured based on the measured temperature. To control.

Japanese Unexamined Patent Publication No. 2016-72477

However, if the temperature of the substrate surface 111 is to be controlled, it is preferable to measure the temperature of the substrate surface 111 with high accuracy, and to measure the temperature of the substrate surface 111 with high accuracy, the temperature sensor 341 is brought closer to the substrate surface 111. Is preferable. However, when the temperature sensor 341 is brought closer to the substrate surface 111, the internal hole 34 in which the temperature sensor 341 is housed becomes longer by that amount, so that the heat drawing performance in the internal hole 34 deteriorates. As a result, the temperature in the vicinity of the internal hole 34 becomes higher than that in the vicinity thereof, and the temperature of the substrate surface 111 varies. By accurately measuring the temperature of the substrate surface 111 in this way, it has been difficult to eliminate the temperature variation of the substrate surface 111.

The holding device of the present disclosure includes an insulator having a front surface and a back surface, a heater member having a heating element arranged inside or on the back surface of the insulator, and a temperature measuring element arranged on the back surface side of the insulator. In a holding device that holds an object on the surface of the insulator, the insulator is made of a material having a higher thermal conductivity than the material forming the insulator, and the temperature of the insulator is measured. It is a holding device provided with a heat transfer portion arranged from the vicinity of the element toward the surface side of the insulator.

According to the present disclosure, the temperature of the object can be measured accurately, and the temperature variation of the object can be reduced.

FIG. 1 is a perspective view showing the electrostatic chuck of the embodiment partially broken. FIG. 2 is a cross-sectional view showing a part of the electrostatic chuck of the embodiment broken in the thickness direction.

[Explanation of Embodiments of the present disclosure]
First, embodiments of the present disclosure will be listed and described.
(1) The holding device of the present disclosure is arranged on an insulator having a front surface and a back surface, a heater member having a heating element arranged inside or on the back surface of the insulator, and the back surface side of the insulator. In a holding device comprising a temperature measuring element and holding an object on the surface of the insulator, the insulator is made of a material having a higher thermal conductivity than the material forming the insulator, and is in the insulator. It is a holding device provided with a heat transfer portion arranged from the vicinity of the temperature measuring element toward the surface side of the insulator.

Since the temperature measuring element is arranged on the back side of the insulator, a large space for arranging the temperature measuring element inside the insulator becomes unnecessary, and the heat drawing performance deteriorates in the vicinity of the temperature measuring element. Can be suppressed. Since the heat on the surface of the insulator is transmitted to the back surface side through the heat transfer portion and is measured by the temperature measuring element, the temperature on the surface of the insulator can be measured accurately.

(2) The insulator has a recess provided on the front surface side with respect to the back surface, and the bottom surface of the recess is arranged on the back surface side of the heater member to measure the temperature. It is preferable that the tip of the element is arranged in the recess.
Since the bottom surface of the recess is provided on the back surface side of the heater member, the size of the recess can be kept to a minimum, and it is possible to prevent the recess from deteriorating the heat drawing performance.

(3) When the direction substantially orthogonal to the surface of the insulator is the vertical direction and the surface side is the upper side, the insulator has a portion directly above the recess and the concave portion in the vertical direction. The heat transfer portion is preferably arranged directly above the portion.
Since the heat transfer portion is arranged directly above the portion, the length of the heat transfer portion can be minimized, and the temperature of the surface of the insulator can be measured quickly.

(4) It is preferable that the heat transfer portion includes a terminal connection portion exposed to the outside of the insulator, and the tip of the temperature measuring element is in contact with the terminal connection portion.
Since the tip of the temperature measuring element is in contact with the terminal connection portion, the heat from the heat transfer portion can be directly transferred to the tip of the temperature measuring element.

(5) It is preferable that the heat transfer portion has a surface side end portion located on the surface side, and the surface side end portion is arranged on the surface side of the heater member.
Since the surface side end of the heat transfer portion can be brought close to the surface of the insulator, the temperature of the surface of the insulator can be measured more accurately.

[Details of Embodiments of the present disclosure]
Specific examples of the holding device of the present disclosure will be described below with reference to the drawings. It should be noted that the present disclosure is not limited to these examples, but is shown by the scope of claims and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

<Electrostatic chuck>
The holding device of the present disclosure is an electrostatic chuck 10 capable of adsorbing and holding a semiconductor wafer, a glass substrate, or the like (hereinafter referred to as “wafer 80”). As shown in FIG. 2, the electrostatic chuck 10 can adsorb a wafer 80, which is a heating target (work), on a chuck surface 21 facing upward in the drawing, and is a disk (for example, having a diameter of 300 mm and a thickness of 3 mm). The ceramic substrate 20 and the disk-shaped base member 60 (for example, having a diameter of 340 mm and a thickness of 20 mm) are joined by a bond material 70. The base member 60 is arranged on the lower side of the ceramic substrate 20.

The electrostatic chuck 10 is used as a table on which the wafer 80 is placed in a process of etching or the like using plasma in a decompressed chamber. The electrostatic chuck 10 is formed with a pin insertion hole 11 that penetrates both the ceramic substrate 20 and the base member 60 in the vertical direction. A lift pin (not shown) is inserted through the pin insertion hole 11, and the wafer 80 can be lifted from the chuck surface 21 by moving the lift pin upward.

In addition to the pin insertion hole 11, the electrostatic chuck 10 is provided with a flow path (gas hole) (not shown) for supplying the inert gas to the chuck surface 21 side. As the inert gas, for example, an inert gas such as helium gas or nitrogen gas can be used. By flowing an inert gas between the wafer 80 and the ceramic substrate 20, the heat conduction between the wafer 80 and the ceramic substrate 20 can be improved.

<Ceramic substrate>
The ceramic substrate 20 includes an insulator 30 made of ceramic, a heater electrode 40 arranged inside the insulator 30, and a chuck electrode 50 arranged between the heater electrode 40 and the chuck surface 21 inside the insulator 30. And have. The heater electrode 40 and the chuck electrode 50 are arranged side by side in the vertical direction, the chuck electrode 50 is arranged on the side close to the chuck surface 21, and the heater electrode 40 is arranged on the lower side of the chuck electrode 50.

Terminals (not shown) are connected to the heater electrode 40 and the chuck electrode 50, respectively. Each terminal is arranged so as to penetrate the base member 60 in the vertical direction. Each terminal is connected to a power source (not shown), and power from each power source can be supplied to the chuck electrode 50 and the heater electrode 40 through each terminal.

<Insulator>
The insulator 30 has an upper surface 34 and a lower surface 35, and is formed by laminating a plurality of ceramic layers. In the following, the direction of the axis orthogonal to the upper surface 34 of the insulator 30 will be described as the vertical direction. Here, orthogonality includes not only the case where the axis and the upper surface 34 intersect at an angle of 90 ° but also the case where the axis intersects at an angle of 85 to 90 °. As shown in FIG. 2, the upper surface 34 of the insulator 30 is located below the chuck surface 21 of the ceramic substrate 20. On the other hand, the lower surface 35 of the insulator 30 is located at the same height as the lower surface of the ceramic substrate 20. The insulator 30 is a sintered body containing alumina, aluminum nitride, yttria, or a composite material of alumina and silicon carbide as a main component. The coefficient of thermal expansion of the insulator 30 is in the range of 3 to 8 ppm / ° C. (for example, 7.6 ppm / ° C.), and its thermal conductivity is 10 to 150 W / m · K.

<Heater electrode>
Inside the insulator 30, a plurality of heating elements 41 constituting the heater electrode 40 are arranged. The heating element 41 is mainly composed of tungsten, molybdenum, an alloy thereof, or a carbide thereof.

Although the heater electrode 40 of the present disclosure is arranged inside the insulator 30, it may be arranged inside the surface of the insulator 30 or inside a heater member (polyimide heater) separate from the insulator 30. As the heating element 41 of the present disclosure, although a conductor obtained by sintering a conductive pattern printed with a conductor paste is used, a metal foil, a metal mesh, or the like may be used.

<Chuck electrode>
The chuck electrode 50 is composed mainly of tungsten, molybdenum, or an alloy thereof. The chuck electrode 50 exhibits an electrostatic adsorption force by applying a voltage. As the type of electrostatic attraction force, Coulomb force, Johnsen-Rahbek force, gradient force and the like can be used. As the chuck electrode 50 of the present disclosure, although a conductor obtained by sintering a conductive pattern printed with a conductor paste is used, a metal foil, a metal mesh, or the like may be used.

<Base member>
The base member 60 is mainly composed of aluminum, an aluminum alloy, a composite of metal and ceramics (Al—SiC), or ceramics (SiC). The base member 60 has a larger diameter than the ceramic substrate 20 so that the entire ceramic substrate 20 can be mounted. The base member 60 has a refrigerant flow path 61 through which a refrigerant flows. The coefficient of thermal expansion of the base member 60 is in the range of 5 to 9 ppm / ° C. (for example, 6.9 ppm / ° C.), and the thermal conductivity is 180 W / m · K, which is higher than that of the insulator 30. Have.

<Bond material>
A bond material 70 is arranged between the upper surface 62 of the base member 60 and the lower surface of the ceramic substrate 20. The bond material 70 is composed mainly of a silicone resin or an epoxy resin. The bond material 70 of the present disclosure uses a paste-like or sheet-like silicone adhesive. The bond material 70 is caused by the role of conducting heat conduction between the ceramic substrate 20 and the base member 60 and the thermal expansion of the ceramic substrate 20 and the base member 60, in addition to the role of adhering the ceramic substrate 20 and the base member 60. It plays a role in relieving stress.

<Temperature sensor>
The electrostatic chuck 10 of the present disclosure includes a temperature sensor 90 for measuring the temperature of the upper surface 34 of the insulator 30 and the chuck surface 21 of the ceramic substrate 20. The temperature sensor 90 has a rod shape that is long in the vertical direction from the inside of the base member 60 to the lower end of the ceramic substrate 20, and has a temperature measuring element such as a thermocouple or a thermistor. The tip of the temperature sensor 90 is a terminal 91 for detecting the temperature. Instead of the temperature sensor 90 of the present disclosure, a chip-shaped thermistor may be embedded in the lower end portion of the insulator 30.

An internal hole 63 for accommodating the temperature sensor 90 is provided inside the base member 60, and the inner circumference of the internal hole 63 is insulated so as to surround the outer periphery of the temperature sensor 90 and having electrical insulation. A cylinder 64 is arranged. A recess 31 for accommodating the terminal 91 is provided at a position corresponding to the internal hole 63 on the lower surface 35 of the insulator 30.

The recess 31 is provided in the insulator 30 and is a bottomed recess 31 that opens downward. Of the inner surfaces of the recess 31, the inner surface of the insulator 30 on the upper surface 34 side is the bottom surface 32. The bottom surface 32 is arranged on the lower surface 35 side of the insulator 30 with respect to the heater electrode 40. A terminal connection portion 26 exposed to the outside of the insulator 30 is formed on the bottom surface 32, and plating is formed on the surface of the terminal connection portion 26. The terminal 91 of the temperature sensor 90 is arranged in the recess 31 in a state of being in contact with the terminal connection portion 26. As the material of the terminal connection portion 26, for example, tungsten, molybdenum, or an alloy thereof is mainly used.

<Heat transfer part>
The ceramic substrate 20 of the present disclosure is made of a material having a higher thermal conductivity than the material forming the insulator 30, and has a heat transfer portion 25 directed from the terminal 91 of the temperature sensor 90 in the insulator 30 toward the upper surface 34 side. I have. The heat transfer portion 25 is composed of the terminal connection portion 26 described above, a plurality of internal wirings 27 extending in the horizontal direction, and a plurality of vias 28 extending in the vertical direction. Although the heat transfer unit 25 is conductive, it is a dummy circuit that is not used for energization. Since the heat transfer portion 25 is embedded inside the insulator 30, no space for accommodating the heat transfer portion 25 is formed inside the insulator 30. The heat transfer portion 25 is made of a material having a higher thermal conductivity than the material forming the insulator 30. As the material of the heat transfer unit 25, for example, tungsten, molybdenum, or an alloy thereof is mainly used.

The heat transfer portion 25 has a configuration in which a via 28 is joined to the upper surface of the terminal connection portion 26, an internal wiring 27 is joined to the upper end of the via 28, and thereafter, the via 28 and the internal wiring 27 are alternately arranged. The upper end of the heat transfer portion 25 of the present disclosure is composed of the internal wiring 27, and is the upper end side end portion 25U. The insulator 30 has a directly above portion 33 that overlaps the recess 31 in the vertical direction, and the heat transfer portion 25 is arranged in a form extending in the vertical direction in the directly above portion 33. The upper surface side end portion 25U of the heat transfer portion 25 is arranged above the heater electrode 40 and below the chuck electrode 50.

Since the heat transfer portion 25 has a higher thermal conductivity than the insulator 30, the heat of the upper surface 34 of the insulator 30 is rapidly transferred to the terminal connection portion 26 mainly via the heat transfer portion 25. Therefore, the temperature of the upper surface 34 of the insulator 30 and the temperature of the terminal connection portion 26 can be brought close to each other. The heat transferred to the terminal connection portion 26 is measured by the terminal 91 of the temperature sensor 90. Further, since no space is formed around the heat transfer portion 25 in the insulator 30, the temperature around the heat transfer portion 25 does not increase due to the deterioration of the heat transfer performance. As a result, the temperature of the wafer 80 adsorbed and held on the chuck surface 21 can be accurately measured, and the temperature variation of the wafer 80 can be reduced.

<Effect of this embodiment>
As described above, the electrostatic chuck 10 of the present embodiment has an insulator 30 having an upper surface 34 and a lower surface 35, a heater electrode 40 having a heating element 41 arranged inside the insulator 30, and a lower surface of the insulator 30. In the electrostatic chuck 10 having a temperature sensor 90 arranged on the 35 side and holding the wafer 80 on the upper surface 34 of the insulator 30, it is made of a material having a higher thermal conductivity than the material forming the insulator 30. The electrostatic chuck 10 is provided with a heat transfer portion 25 arranged from the vicinity of the temperature sensor 90 in the insulator 30 toward the upper surface 34 side of the insulator 30.

Since the temperature sensor 90 is arranged on the lower surface 35 side of the insulator 30, a large space for arranging the temperature sensor 90 inside the insulator 30 becomes unnecessary, and the heat drawing performance deteriorates in the vicinity of the temperature sensor 90. Can be suppressed. Since the heat of the upper surface 34 of the insulator 30 is transmitted to the lower surface 35 side through the heat transfer portion 25 and is measured by the temperature sensor 90, the temperature of the upper surface 34 of the insulator 30 can be measured accurately.

The insulator 30 has a recess 31 recessed on the upper surface 34 side with respect to the lower surface 35, and the bottom surface 32 of the recess 31 is arranged on the lower surface 35 side of the heater electrode 40, and the temperature sensor 90 has a recess 31. The tip is preferably arranged in the recess 31.
Since the bottom surface 32 of the recess 31 is provided on the lower surface 35 side of the heater electrode 40, the size of the recess 31 can be kept to a minimum, and it is possible to prevent the recess 31 from deteriorating the heat drawing performance.

When the direction substantially orthogonal to the upper surface 34 of the insulator 30 is the vertical direction and the upper surface 34 side is the upper side, the insulator 30 has a directly above portion 33 that overlaps the recess 31 in the vertical direction, and is a heat transfer unit. 25 is preferably arranged on the directly above portion 33.
Since the heat transfer portion 25 is arranged on the directly above portion 33, the length of the heat transfer portion 25 can be minimized, and the temperature of the upper surface 34 of the insulator 30 can be quickly measured.

It is preferable that the heat transfer portion 25 includes a terminal connection portion 26 exposed to the outside of the insulator 30, and the terminal 91 of the temperature sensor 90 is in contact with the terminal connection portion 26.
Since the terminal 91 of the temperature sensor 90 is in contact with the terminal connection portion 26, the heat from the heat transfer portion 25 can be directly transferred to the terminal 91 of the temperature sensor 90.

It is preferable that the heat transfer portion 25 has an upper surface side end portion 25U located on the upper surface side 34 side, and the upper surface side end portion 25U is arranged on the upper surface side 34 side of the heater electrode 40.
Since the upper surface side end portion 25U of the heat transfer portion 25 can be brought closer to the upper surface 34 of the insulator 30, the temperature of the upper surface 34 of the insulator 30 can be measured more accurately.

<Other embodiments>
(1) In the above embodiment, although the end portion of the heat transfer portion 25 on the lower surface 35 side is in contact with the terminal 91 of the temperature sensor 90, the end portion of the heat transfer portion on the lower surface 35 side is the terminal 91 of the temperature sensor 90. It may be the one which is not in contact with the terminal 91 and is arranged in the vicinity of the terminal 91.

(2) In the above embodiment, although the terminal 91 of the temperature sensor 90 is arranged in the recess 31, the terminal 91 may be arranged in the lower surface 35 of the insulator 30.

(3) In the above embodiment, although the heat transfer portion 25 is arranged so as to extend in the vertical direction in the portion 33 directly above the recess 31, a part of the heat transfer portion extends diagonally upward from the recess 31 and is directly above the portion 33. It may be arranged in an area other than the above.

(4) In the above embodiment, although the terminal connection portion 26 is exposed to the outside of the insulator 30, the terminal connection portion may be embedded inside the insulator 30 in the vicinity of the lower surface 35.

(5) In the above embodiment, the description is made on the premise that the temperature of the heat transfer unit 25 is the same as that of the surroundings. However, for example, when the heat transfer unit 25 has a temperature singularity lower than that of the surroundings. May adjust the temperature so as to heat the heater electrode 40 around the heat transfer unit 25.

(6) In the above embodiment, the heat transfer portion 25 is composed of the via 28 and the internal wiring 27, but a metal bulk body may be inserted as the heat transfer portion.

10 ... Electrostatic chuck 11 ... Pin insertion hole 20 ... Ceramic substrate 21 ... Chuck surface 25 ... Heat transfer part 25U ... Top surface side end (front surface side end) 26 ... Terminal connection 27 ... Internal wiring 28 ... Via 30 ... Insulation Body 31 ... Recessed portion 32 ... Bottom surface 33 ... Directly above part 34 ... Top surface (front surface) 35 ... Bottom surface (back surface)
40 ... Heater electrode (heater member) 41 ... Heating element 50 ... Chuck electrode 60 ... Base member 61 ... Refrigerant flow path 62 ... Top surface 63 ... Internal hole 64 ... Insulation cylinder 70 ... Bond material 80 ... Wafer (object)
90 ... Temperature sensor 91 ... Terminal (tip)

Claims (5)

Insulators with front and back surfaces and
A heater member having a heating element arranged inside or on the back surface of the insulator, and
In a holding device comprising a temperature measuring element arranged on the back surface side of the insulator and holding an object on the surface of the insulator.
It is made of a material having a higher thermal conductivity than the material forming the insulator, and has a heat transfer portion arranged from the vicinity of the temperature measuring element in the insulator toward the surface side of the insulator. Holding device. The insulator has a recess provided on the front surface side with respect to the back surface.
The bottom surface of the recess is arranged on the back surface side of the heater member.
The holding device according to claim 1, wherein the tip of the temperature measuring element is arranged in the recess. When the direction substantially orthogonal to the surface of the insulator is the vertical direction and the surface side is the upper side, the insulator has a portion directly above the recess and the concave portion in the vertical direction.
The holding device according to claim 2, wherein the heat transfer unit is arranged directly above the heat transfer unit. The heat transfer portion includes a terminal connection portion exposed to the outside of the insulator, and the tip of the temperature measuring element is in contact with the terminal connection portion, according to any one of claims 1 to 3. The holding device described. The heat transfer portion has a surface side end portion located on the surface side, and has a surface side end portion.
The holding device according to any one of claims 1 to 4, wherein the surface side end portion is arranged on the surface side of the heater member.

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