JP2018142488A - Ceramic heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic heater capable of making the temperature in a heating zone uniform and sufficiently securing a temperature difference from another heating zone having a different target temperature. SOLUTION: In a ceramic heater 5, a heat dispersion layer 15 having a higher thermal conductivity than a ceramic material (that is, heat is easily transferred) is arranged between the heat generating layer 13 and the back surface of each heat generating layer 13. , The temperature in each heating zone KZ in which each heat generating layer 13 is arranged can be easily made uniform. Moreover, since each heat dispersion layer 15 is arranged for each heat generation pattern 47 of the heat generation layer 13, it is possible to sufficiently secure a temperature difference from other heating zones KZ having different target temperatures. That is, the temperature between the heating zones KZ can be separated. [Selection diagram] Fig. 5

Description

  The present invention relates to a ceramic heater capable of heating a workpiece such as a semiconductor wafer, for example.

  Conventionally, in a semiconductor manufacturing apparatus, a process such as dry etching (for example, plasma etching) is performed on a semiconductor wafer (for example, a silicon wafer). In order to increase the accuracy of this dry etching, it is necessary to securely fix the semiconductor wafer. As a fixing means for fixing the semiconductor wafer, an electrostatic chuck for fixing the semiconductor wafer by electrostatic attraction is used. Yes.

  Some electrostatic chucks have a function of adjusting the temperature of a semiconductor wafer attracted to an attracting surface. For example, there is a technique for heating a semiconductor wafer on an adsorption surface using a ceramic heater in which a linear heating element is disposed in a ceramic substrate. In the electrostatic chuck, a cooling metal base is usually connected to a surface (back surface) opposite to the suction surface (front surface) of the ceramic heater.

  Furthermore, in order to precisely heat the electrostatic chuck, a ceramic heater in which the ceramic substrate is divided into a plurality of heating zones (that is, heating regions: segments) in plan view has been developed. Specifically, a ceramic heater with a multi-zone heater has been proposed in which a heating element capable of individually heating each heating zone is arranged for each heating zone to improve the temperature adjustment function of the ceramic substrate (Patent Document 1). reference).

  In recent years, in order to perform temperature control with higher accuracy, the demand for further multi-zone (multi-zone) has increased, and for example, more than 100 heating zones have been studied.

JP 2005-166354 A JP 2008-166509 A

  By the way, in order to improve the temperature adjustment function (i.e., temperature controllability) of the ceramic substrate, it is desirable to accurately adjust the temperature for each location (i.e., each heating zone) controlled to the target temperature. In addition, when there are many heating zones, there is a problem that it is not easy to improve temperature controllability.

  That is, as shown in FIG. 22, when controlling to a target temperature (that is, target temperature) for each heating zone (segment) in which a heating element is disposed, Although it is desired to make the temperature uniform in the heating zone, the countermeasure is not easy.

  Specifically, for example, as shown in FIG. 22B, it is desirable to control so that there is a clear temperature difference between heating zones (especially in the vicinity of the boundary) (see the temperature curve shown by a solid line). There is a problem that it is difficult to make a clear temperature difference between heating zones (especially in the vicinity of the boundary) (see a temperature curve indicated by a broken line).

  Separately from this, for example, Patent Document 2 discloses a technique in which a heat conduction member is disposed between a heating element and a metal base to make the temperature distribution in the plane direction of the ceramic heater uniform. However, with this technique, it is not possible to make a temperature difference between the heating zones (ie, to separate the temperatures).

  The present invention has been made in view of the above problems, and the object thereof is to make the temperature in the heating zone uniform and to ensure a sufficient temperature difference from other heating zones having different target temperatures. It is to provide a ceramic heater.

  (1) A first aspect of the present invention relates to a ceramic heater in which a plurality of heat generating layers that generate heat by energization are arranged in a plane direction inside a ceramic substrate having a front surface and a back surface.

  In this ceramic heater, a heat dispersion layer having a higher thermal conductivity than the ceramic material constituting the ceramic substrate is disposed for each heat generating layer between the heat generating layer and the back surface inside the ceramic substrate. Furthermore, in a plan view of the ceramic substrate as viewed from the thickness direction, the heat generation layer has a linear heat generation pattern, and the heat generation pattern has a bent portion.

  As described above, in the first aspect, the heat dispersion layer having a higher thermal conductivity than the ceramic material (that is, heat is easily transmitted) is disposed between the heat generation layer and the back surface for each heat generation layer. The temperature in each heating zone in which the heat generating layer is disposed can be made uniform.

  Furthermore, in the first aspect, since the heat dispersion layer is arranged for each heat generating layer having a heat generation pattern that is linear and bent, a sufficient temperature difference from other heating zones having different target temperatures is ensured. Can do. That is, the temperature between each heating zone can be separated (ie, separated).

As described above, in the first aspect, the temperature in the heating zone is made uniform, and a remarkable effect is obtained that a temperature difference from the other heating zones can be sufficiently secured.
In addition, by disposing the heat dispersion layer between the heat generation layer and the back surface, the heat distribution layer is part of the wiring portion (for example, a power supply path from the pair of terminal portions to the heat generation layer: for example, the internal wiring layer). Can be diverted as Therefore, in the thickness direction of the ceramic substrate, for example, a space for newly disposing the heat dissipating layer is not required separately from the internal wiring layer, so that there is an advantage that the heat dispersive layer can be disposed without increasing the thickness of the ceramic substrate.

(2) In the second aspect of the present invention, in a plan view, in each heat generation layer, a heat dispersion layer is also disposed in a region between the linear heat generation patterns disposed adjacent to each other among the heat generation patterns. Yes.
In the second aspect, in the heat generation pattern of the same heat generation layer, since the heat dispersion layer is disposed between the adjacent heat generation patterns, the temperature in each heating zone can be made uniform.

(3) In the third aspect of the present invention, the first distance between the heat generation layer and the heat dispersion layer is shorter than the second distance between the heat dispersion layer and the back surface.
In the third aspect, since the heat dispersion layer is disposed at a position closer to the heat generation layer than the back surface, it is possible to more easily equalize the heating zones and to separate the temperatures between the heating zones. be able to.

  (4) In the fourth aspect of the present invention, the heat dispersion layer has a conductive pad part having a larger area than the pad part and spaced from the pad part in plan view, and the entire circumference of the pad part. And a main heat dispersion portion having electrical conductivity surrounding. Furthermore, a first via that electrically connects the pad portion and the heat generating layer and a second via that electrically connects the heat generating layer and the main heat dispersion portion are provided. In addition, a pair of terminal portions for supplying power to the heat generating layer are electrically connected to the pad portion and the main heat dispersion portion, respectively.

  In the fourth aspect, heating is performed by supplying power from the pair of terminal portions to the heat generation layer (specifically, the heat generation pattern) through the first via and the pad portion, the second via and the main heat dispersion portion. The zone can be heated.

In addition, since the power supply path from the pair of terminal portions to the heat generating layer can be shortened, the configuration of the electrode supply path can be simplified.
Furthermore, since the main heat dispersion portion having a large area is disposed so as to surround the pad portion, it is possible to improve the heat uniformity in the heating zone.

  (5) In the fifth aspect of the present invention, the heat dispersion layer has a pair of conductive pad portions having a larger area than the pad portions and a space between the pad portions in plan view. And a main heat dispersion part having conductivity surrounding the entire circumference. Further, the heat generating layer is electrically connected to the pair of pad portions, and a pair of terminal portions for supplying power to the heat generating layer are electrically connected to the pair of pad portions, respectively.

In the fifth aspect, the heating zone can be heated by supplying power from the pair of terminal portions to the heat generation layer (specifically, the heat generation pattern) via the pair of pad portions.
In addition, since the power supply path from the pair of terminal portions to the heat generating layer can be shortened, the configuration of the electrode supply path can be simplified.

Furthermore, since the main heat dispersion part with a large area is arrange | positioned so that a pair of pad part may be enclosed, the thermal uniformity in a heating zone can be improved.
<Each configuration of the present invention will be described below>
The surface of the ceramic heater is a surface on which a member to be heated is disposed (for example, an attracting surface for an electrostatic chuck), and the back surface is a surface opposite to the surface (for example, a metal base for an electrostatic chuck). Surface to be joined).

  A ceramic substrate is a substrate (plate-shaped member) containing ceramic as a main component (50% by mass or more). Examples of the ceramic material include aluminum oxide (alumina), aluminum nitride, yttrium oxide (yttria), and the like.

  The heat generation layer (and hence the heat generation pattern) is a layer made of a resistance heating element that generates heat when energized. Examples of the material of the heat generation layer include tungsten, tungsten carbide, molybdenum, molybdenum carbide, tantalum, and platinum.

The plane direction is the plane direction in which the ceramic substrate spreads. That is, this is a direction in which a plane perpendicular to the thickness direction of the ceramic substrate spreads.
The outer peripheral shape of the heat dispersion layer in plan view is a shape along the outer periphery of the heat generating layer, such as a rectangular shape or a circular shape. For example, the inside of the area | region which connected the convex part of the adjacent heat generation pattern among the outer periphery of the heat generation pattern of a heat generating layer by planar view is mentioned. Moreover, the inside of the area | region formed when the outer periphery of a heat generation pattern is made to surround with a string by planar view is mentioned.

  As the material of the heat dispersion layer, for example, a conductive material made of tungsten, molybdenum or the like can be used, but is not limited thereto. For example, when the heat dispersion layer is not used for power feeding, a material different from the conductive material can be employed.

  That is, since the heat dispersion layer has a higher thermal conductivity than the ceramic material constituting the ceramic substrate, various materials corresponding to the ceramic material can be used. For example, although it depends on the ceramic material, graphite, SiC (silicon carbide), AlN (aluminum nitride), or the like can be used.

  The terminal part, the via, and the pad part are conductive parts made of, for example, tungsten or molybdenum.

It is a perspective view showing a part of the electrostatic chuck of the first embodiment. It is sectional drawing which fractures | ruptures the electrostatic chuck of 1st Embodiment in the thickness direction, and shows the part typically. It is a top view which shows typically the arrangement | positioning of the several heating zone and heat generating layer of a ceramic heater. (A) is a top view which shows a heat_generation | fever pattern, (b) is a top view which shows a heat | fever dispersion layer, (c) is a top view which shows the state which accumulated the heat | fever pattern and the heat | fever dispersion layer. (A) is an explanatory view schematically showing a ceramic substrate broken in the thickness direction (cross section AA in FIG. 4), and (b) is an explanatory view schematically showing the ceramic substrate in the thickness direction (cross section BB in FIG. 4). FIG. 2 is an explanatory view schematically showing a broken and enlarged view. (A) is a plan view showing a state in which the heat generation pattern of the second embodiment and the heat dispersion layer are overlaid, (b) is a plan view showing the heat dispersion layer, and (c) is a ceramic substrate in the thickness direction (FIG. 6 (a) is an explanatory view schematically showing a broken and enlarged view (in the CC cross section). FIG. It is a top view which shows the state which accumulated the heat_generation | fever pattern and heat dispersion layer of 2nd Embodiment. (A) is a plan view showing a heat generation pattern of the reference model of Experimental Example 1, and (b) is an explanatory view showing a heat generation state (temperature distribution) of the reference model of Experimental Example 1. FIG. (A) is a plan view showing the heat generation pattern of Example A of the invention of Example 1 and the heat dispersion layer in an overlapping manner, (b) is an explanatory view showing the heat generation state of Example A of the invention, and (c) is Comparative Example 1. FIG. 9D is a plan view showing the heat generation pattern and the heat dispersion layer in an overlapping manner, FIG. 9D is an explanatory view showing the heat generation state of Comparative Example 1, and FIG. FIG. 4F is an explanatory view showing a heat generation state of Comparative Example 2. It is a graph which shows the temperature in the temperature plot direction of the reference | standard model of Experimental example 1, this invention example A, and comparative examples 1 and 2. FIG. (A) is a plan view showing a heat generation pattern of the reference model of Experimental Example 2, and (b) is an explanatory view showing a heat generation state of the reference model of Experimental Example 1. FIG. (A) is a plan view showing an exothermic pattern and a heat dispersion layer of Invention Example A of Experimental Example 2 superimposed on each other, (b) is an explanatory view showing a heat generation state of Invention Example A, and (c) is Comparative Example 1. FIG. 9D is a plan view showing the heat generation pattern and the heat dispersion layer in an overlapping manner, FIG. 9D is an explanatory view showing the heat generation state of Comparative Example 1, and FIG. FIG. It is a graph which shows the temperature in the temperature plot direction of the reference | standard model of Experimental example 2, the example A of this invention, and the comparative example 1. FIG. (A) is sectional drawing which shows arrangement | positioning of the heat_generation | fever pattern and heat dispersion layer in the thickness direction of this invention example B of experiment example 3, (b) shows the heat_generation | fever state in the experiment conditions which show the thermal uniformity of this invention example B. Explanatory drawing, (c) is explanatory drawing which shows the heat_generation | fever state in the experimental condition which shows the thermal separability of the example B of this invention. (A) is sectional drawing which shows arrangement | positioning of the heat_generation | fever pattern and heat dispersion layer in the thickness direction of this invention example C of experiment example 3, (b) shows the heat_generation | fever state in the experiment conditions which show the thermal uniformity of this invention example C. Explanatory drawing, (c) is explanatory drawing which shows the heat_generation | fever state in the experimental condition which shows the heat separability of the example C of this invention. (A) is the graph which shows the temperature in the temperature plot direction in the experimental conditions which show the thermal uniformity of this invention example B of this invention example 3, and this invention example C, (b) is this invention example B of experiment example 3, this invention example. It is a graph which shows the temperature in the temperature plot direction in the experimental condition which shows the thermal separability of C. (A) is a plan view showing the heat generation pattern of Example D of the invention of Example 4 and the heat dispersion layer in an overlapping manner, and (b) is an explanatory view showing the heat generation state of Example D of the invention. (A) is a top view which overlaps and shows the heat_generation | fever pattern and heat dispersion layer of the comparative example 3 of Experimental example 4, (b) is explanatory drawing which shows the heat_generation | fever state of the comparative example 3. FIG. 6 is a graph showing temperatures in the temperature plot direction of Invention Examples A and D of Experimental Example 4 and Comparative Example 3. It is explanatory drawing which shows collectively the experimental conditions and experimental result of Experimental Examples 1-4. It is a top view which shows the state which accumulated the heat-generation pattern and heat dispersion layer of other embodiment. It is explanatory drawing of a prior art.

[1. First Embodiment]
Here, as a first embodiment, for example, a ceramic heater used for an electrostatic chuck capable of attracting and holding a semiconductor wafer is taken as an example.
[1-1. overall structure]
First, the structure of the electrostatic chuck of the first embodiment will be described.

  As shown in FIG. 1, the electrostatic chuck 1 according to the first embodiment is a device for adsorbing a semiconductor wafer 3 as a workpiece on the upper side of FIG. 1, and a ceramic heater 5 and a metal base 7 are laminated. And bonded by the adhesive layer 9.

  The upper surface (upper surface: adsorption surface) of FIG. 1 of the ceramic heater 5 is the first main surface S1 (that is, the front surface), and the lower surface is the second main surface S2 (that is, the back surface). The upper surface of the metal base 7 is the third main surface S3, and the lower surface is the fourth main surface S4.

  Among these, the ceramic heater 5 has a disk shape, and is composed of a ceramic substrate (insulating substrate) 17 having an adsorption electrode (electrostatic electrode) 11, a heat generation layer 13, and a heat dispersion layer 15. The adsorption electrode 11 and the heat generation layer 13 are embedded in the ceramic substrate 17 and the heat dispersion layer 15 is embedded therein.

  The metal base 7 has a disk shape larger in diameter than the ceramic heater 5 and is joined to the ceramic heater 5 coaxially. The metal base 7 is provided with a flow path (cooling path) 19 through which a cooling fluid (refrigerant) flows in order to cool the ceramic substrate 17 (and thus the semiconductor wafer 3). As the cooling fluid, for example, a cooling liquid such as a fluorinated liquid or pure water can be used.

  The electrostatic chuck 1 is provided with a plurality of lift pin holes 21 or the like into which lift pins (not shown) are inserted so as to penetrate the electrostatic chuck 1 in the thickness direction. The lift pin hole 21 is also used as a flow path (cooling gas hole) for cooling gas supplied to the first main surface S1 side in order to cool the semiconductor wafer 3.

  In addition to the lift pin holes 21, a cooling gas hole (not shown) may be provided. As the cooling gas, for example, an inert gas such as helium gas or nitrogen gas can be used.

Next, each configuration of the electrostatic chuck 1 will be described in detail with reference to FIG.
<Ceramic heater>
As schematically shown in FIG. 2, the ceramic heater 5 (and hence the ceramic substrate 17) has a third main surface S3 of the metal base 7 on the second main surface S2 side by an adhesive layer 9 made of, for example, silicone. It is joined to the side.

  The ceramic substrate 17 is formed by laminating a plurality of ceramic layers 23 (see FIG. 5A), and is an alumina sintered body mainly composed of alumina. The alumina sintered body is an insulator (dielectric).

  Inside the ceramic substrate 17, as will be described in detail later from above in FIG. 2, an adsorption electrode 11, a plurality of heat generation layers 13, a plurality of heat dispersion layers 15, and the like are arranged. In FIG. 2, the plurality of heat generating layers 13 and the like are schematically shown.

  Among these, the plurality of heat generating layers 13 are arranged on the first plane HM1, and the plurality of heat dispersion layers 15 are arranged on the second plane HM2. The first and second planes HM1 and HM2 are planes extending perpendicularly to the thickness direction (that is, parallel to the plane direction) at different positions away from the ceramic substrate 17 by a predetermined distance in the thickness direction (vertical direction in FIG. 2). Plane).

  Further, as will be described later, the ceramic substrate 17 is divided into a plurality of heating zones KZ (see FIG. 3) in a plan view viewed from the thickness direction, and the heating layer 13 and the heat dispersion are respectively provided in each heating zone KZ. Layer 15 is disposed. That is, the ceramic substrate 17 has a configuration in which the plurality of heat generating layers 13 and the plurality of heat dispersion layers 15 are arranged in plan view.

  Each heat generating layer 13 is electrically connected to the power supply terminal 25. Specifically, each heat generating layer 13 has its both ends (a pair of end portions 13a and 13b) connected to one of the ceramic substrates 17 via the wiring portion 27 so that the temperature can be controlled independently. On the side (that is, the second main surface S2 side), each pair of power feeding terminals 25 is electrically connected.

  As will be described later, the wiring portion 27 is configured to supply power to the heat generating layer 13. The first via 29, the second via 31, the third via 33, the fourth via 35, the fifth via 37, the internal wiring layer 39, A terminal portion (that is, a terminal pad) 40 is provided, and the power supply terminal 25 is joined to the terminal portion 40. The wiring part 27 is made of, for example, tungsten.

The adsorption electrode 11 is electrically connected to a known electrode terminal (not shown) for applying a voltage.
<Metal base>
The metal base 7 is made of metal made of aluminum or an aluminum alloy. In addition to the cooling path 19 and the lift pin hole 21, the metal base 7 is formed with through portions 41 that are through holes in which the electrode terminals and the power feeding terminals 25 are disposed.

  A plurality of internal holes 43 are provided on the fourth main surface S4 side of the electrostatic chuck 1 so as to accommodate the power supply terminals 25 from the fourth main surface S4 to the inside of the ceramic heater 5. The penetrating portion 41 of the metal base 7 constitutes a part of the internal hole 43.

An insulating tube 45 having electrical insulation is disposed in the internal hole 43 that accommodates the electrode terminal and the power feeding terminal 25.
<Adsorption electrode>
The adsorption electrode 11 is composed of, for example, an electrode having a circular planar shape. When the electrostatic chuck 1 is used, a DC high voltage is applied to the adsorption electrode 11, thereby generating an electrostatic attractive force (adsorption force) for adsorbing the semiconductor wafer 3. It is used to adsorb and fix the semiconductor wafer 3.

In addition to the above, various known configurations (monopolar or bipolar electrodes, etc.) can be employed for the adsorption electrode 11. The adsorption electrode 11 is made of a conductive material such as tungsten.
[1-2. Configuration of heat generation layer and heat dispersion layer]
Next, the structure of the heat generating layer 13 and the heat dispersion layer 15 which are the main parts of the first embodiment will be described.

  As shown in FIG. 3, the ceramic substrate 17 (and hence the ceramic heater 5) has a plurality of heating zones KZ in plan view, and the temperature of each heating zone KZ is independent in each heating zone KZ. The heat generating layers 13 constituted by the linear heat generating patterns 47 are arranged one by one so that they can be adjusted.

  Note that the number of the heating zones KZ is, for example, 200 in the range of 100 or more, for example, but is simplified in FIG. 3 (that is, the number of the heating zones KZ is reduced). The heating layer 13 (and hence the heating pattern 47) is a resistance heating element made of a metal material (such as tungsten) that generates heat when a voltage is applied and a current flows.

  On the other hand, the heat dispersion layer 15 is made of the same conductive material as that of the heat generation layer 13. Specifically, the heat dispersion layer 15 is made of a material (for example, tungsten) having a higher thermal conductivity than the ceramic material (that is, alumina) constituting the ceramic substrate 17.

<Planar shape of heat generation layer and heat dispersion layer>
As shown in FIG. 4A, in the heating zone KZ, the heat generating layer 13 including the heat generating pattern 47 having a meandering shape is formed inside the heating zone KZ by a predetermined distance from the outer periphery of the heating zone KZ. Yes. Note that circular ends 13 a and 13 b are formed at both ends of the linear heat generation pattern 47.

Further, as shown in FIG. 4B, the heat dispersion layer 15 has a rectangular outer periphery in plan view, and is provided inside a predetermined distance from the outer periphery of the heating zone KZ.
The heat distribution layer 15 includes a circular pad portion 15a, a main heat distribution portion 15b having a larger area than the pad portion 15a and a band-like space between the pad portion 15a and surrounding the entire periphery of the pad portion 15a. It is composed of

  In addition, when the space | interval between the pad part 15a and the main heat dispersion | distribution part 15b becomes large, it will become difficult to disperse | distribute heat within the heating zone KZ and to equalize | homogenize. For this reason, it is necessary to maintain an insulation between the pad portion 15a and the main heat dispersion portion 15b, while maintaining an interval that does not hinder heat dispersion. Further, when the area of the pad portion 15a is increased, the effects of heat uniformity and heat dispersibility of the main heat dispersion portion 15b are reduced. Therefore, it is preferable to make the area of the pad portion 15a as small as possible.

  Further, as shown in FIG. 4C, the heat dispersion layer 15 (specifically, the main heat dispersion portion 15b) is located at a position overlapping the heat generation layer 13 so as to include the outermost portion of the heat generation layer 13 in plan view. Has been placed. That is, the heat generation pattern 47 is arranged on the inner side of the outer periphery of the heat dispersion layer 15 on the inner side of the heating zone KZ by a predetermined distance.

  Further, the heat dispersion layer 15 is also disposed in a region between the heat generation patterns 47 arranged adjacent to each other among the heat generation patterns 47 formed to meander in a plan view. That is, the heat dispersion layer 15 is formed so as to enter between adjacent heat generation patterns 47.

<Configuration of heat generation layer and heat dispersion layer>
As shown in FIG. 5A, the heat generating layer 13 (and hence the heat generating pattern 47) is disposed along the plane direction (the left-right direction in FIG. 5) of the ceramic substrate 17, and the heat dispersion layer 15 is the heat generating layer 13. Further, they are arranged in the plane direction on the second main surface S2 side.

  Specifically, the first distance t1 between the heat generation layer 13 and the heat dispersion layer 15 is set to be shorter than the second distance t2 between the heat dispersion layer 15 and the second main surface S2 (that is, the back surface). (Ie, t1 <t2).

  5B, the first via 29 that electrically connects the pad portion 15a and the heat generating layer 13 and the second via that is electrically connected to the heat generating layer 13 and the main heat dispersing portion 15b. The pair of terminal portions 40 for supplying power to the heat generating layer 13 are electrically connected to the pad portion 15a and the main heat dispersion portion 15b, respectively.

That is, the end portion 13a of the heat generation pattern 47 is connected to one terminal portion 40 via the first via 29, the pad portion 15a, the third via 33, and the like, and the other end portion 13b of the heat generation pattern 47 is The second via 31, the main heat dispersion part 15 b, the fourth via 35, etc. are connected to the other terminal part 40.
[1-3. Production method]
Next, a method for manufacturing the electrostatic chuck 1 of the first embodiment will be briefly described.

(1) As a raw material of the ceramic substrate 17, the main components of Al ₂ O ₃ : 92 wt%, MgO: 1 wt%, CaO: 1 wt%, and SiO ₂ : 6 wt% are mixed to form a ball mill. Then, after wet grinding for 50 to 80 hours, dehydrated and dried.

(2) Next, a solvent or the like is added to the powder and mixed with a ball mill to form a slurry.
(3) Next, this slurry is degassed under reduced pressure, and then poured out into a flat plate shape, slowly cooled, and the solvent is diffused to form each alumina green sheet that becomes each ceramic layer 23.

And the space used as the lift pin hole 21 grade | etc., And the through hole used as each via | veer are opened to a required location with respect to each alumina green sheet.
(4) Further, a tungsten powder is mixed in the raw material powder for the alumina green sheet to form a slurry to obtain a metallized ink.

  (5) Then, in order to form the adsorption electrode 11, the heat generation layer 13, the heat dispersion layer 15, the terminal portion 40, etc., the adsorption electrode 11, the heat generation layer 13 on the alumina green sheet is formed using the metallized ink. Each unfired pattern is printed by a normal screen printing method at a location corresponding to a location where the heat dispersion layer 15 and the terminal portion 40 are formed. In order to form each via, metallized ink is filled into the through hole.

(6) Next, the alumina green sheets are aligned so that necessary spaces such as lift pin holes 21 are formed, and thermocompression-bonded to form a laminated sheet.
(7) Next, each thermocompression-bonded laminated sheet is cut into a predetermined shape (that is, a disc shape).

(8) Next, each cut laminated sheet is fired in a reducing atmosphere in the range of 1400 to 1600 ° C. (for example, 1550 ° C.) for 5 hours (main firing) to produce each alumina sintered body. .
(9) Then, after firing, necessary processing such as processing on the first main surface S1 side is performed on each alumina sintered body to produce the ceramic substrate 17.

(10) Next, a terminal fitting (not shown) is brazed to the terminal portion 40 on the second main surface S2 of the ceramic substrate 17.
(11) Separately, the metal base 7 is manufactured. Specifically, the metal base 7 is formed by performing cutting or the like on the metal plate.

(12) Next, the metal base 7 and the ceramic substrate 17 are joined and integrated.
(13) Next, the power supply terminal 25 and the like are arranged to complete the electrostatic chuck 1.
[1-4. effect]
Next, the effect of the first embodiment will be described.

  (1) In the ceramic heater 5 of the first embodiment, heat having a higher thermal conductivity (that is, heat is easily transmitted) between the heat generating layer 13 and the back surface (that is, the second main surface S2) than the ceramic material. Since the dispersion layer 15 is disposed for each heat generating layer 13, the temperature in each heating zone KZ in which each heat generating layer 13 is disposed can be easily made uniform.

  Moreover, in the first embodiment, the heat generation pattern 47 that is bent in a linear shape of the heat generation layer 13 is arranged on the inner side of the outer periphery of each heat dispersion layer 15 in plan view, so that other target temperatures are different. A sufficient temperature difference from the heating zone KZ can be secured. That is, the temperature between the heating zones KZ can be separated (that is, separated).

  Thus, in the first embodiment, the temperature in the heating zone KZ can be made uniform, and a significant effect can be obtained that a temperature difference from the other heating zones KZ can be sufficiently secured.

  By disposing the heat dispersion layer 15 between the heat generation layer 13 and the back surface, the heat distribution layer 15 is connected to the wiring portion 27 (for example, a power supply path from the pair of terminal portions 40 to the heat generation layer 13: It can be used as a part of the wiring layer 39). For this reason, in the thickness direction of the ceramic substrate 17, for example, a space for newly disposing the heat dispersion layer 15 is not required separately from the internal wiring layer 39, and thus the heat dispersion layer 15 can be disposed without increasing the thickness of the ceramic substrate 17.

  Furthermore, in the first embodiment, by arranging the heat dispersion layer 15 between the heat generating layer 13 and the metal base 7, that is, at a position where there is a lot of heat exchange, the effects of heat uniformity and heat dispersion are further improved. There is an advantage that it is easy to obtain.

  (2) In the first embodiment, the heat dispersion layer 15 is also provided in a region between the linear heat generation patterns 47 arranged adjacent to each other in the heat generation patterns 47 in each heat generation layer 13 in plan view. Has been placed.

  That is, in the heat generation pattern 47 of the same heat generation layer 13, since the heat dispersion layer 15 is disposed between the adjacent heat generation patterns 47, the temperature in each heating zone KZ can be made uniform.

(3) In the first embodiment, the first distance t1 between the heat generating layer 13 and the heat dispersion layer 15 is shorter than the second distance t2 between the heat dispersion layer 15 and the back surface.
That is, since the heat dispersion layer 15 is disposed at a position closer to the heat generation layer 13 than the back surface, the heat uniformity in each heating zone KZ is further improved, and the temperature between the heating zones KZ can be separated. it can.

  (4) In the first embodiment, the heat generating layer 13 (specifically, the heat generation pattern) is connected from the pair of terminal portions 40 through the first via 29 and the pad portion 15a, the second via 31 and the main heat dispersion portion 15b. The heating zone KZ can be heated by supplying electric power to 47).

That is, power can be easily supplied to the heat generating layer 13 (specifically, the heat generating pattern 47) by such a simple power supply configuration (particularly a configuration in which the power supply path is short).
Moreover, since the main heat dispersion part 15b with a large area is arrange | positioned so that the pad part 15a may be enclosed, there exists an advantage that the thermal uniformity in the heating zone KZ can be improved.
[1-5. Correspondence of wording]
In the first embodiment, the ceramic heater 5, the heat generation layer 13, the heat dispersion layer 15, the pad portion 15a, the main heat dispersion portion 15b, the ceramic substrate 17, and the terminal portion 40 are respectively the ceramic heater and the heat generation layer of the present invention. This corresponds to an example of a heat dispersion layer, a pad portion, a main heat dispersion portion, a ceramic substrate, and a terminal portion.
[2. Second Embodiment]
Next, the second embodiment will be described, but the description similar to that of the first embodiment will be omitted or simplified. In addition, the same number is attached | subjected to the structure similar to 1st Embodiment.

In the second embodiment, two pad portions are provided in the heat dispersion layer.
In the second embodiment, as shown in FIGS. 6A and 6B, the heat distribution layer 51 has a larger area than the pair of circular pad parts 51a and 51b and the pad parts 51a and 51b in plan view. And a main heat dispersion part 51c surrounding the entire circumference of each pad part 51a, 51b with a band-like space between each pad part 51a, 51b.

  As shown in FIG. 6C, the heat generating layer 13 (and hence the heat generating pattern 47) is electrically connected to the pair of pad portions 51a and 51b, and a pair of terminals for supplying power to the heat generating layer 13. The portions 40 are electrically connected to the pair of pad portions 51a and 51b, respectively.

  That is, the end portion 13 a of the heat generation pattern 47 is connected to the one terminal portion 40 via the first via 29, one pad portion 51 a, the third via 33, and the like, and the other end portion of the heat generation pattern 47. 13b is connected to the other terminal portion 40 via the second via 31, the other pad portion 51b, the fourth via 35, and the like.

The second embodiment also has the same effect as the first embodiment.
[3. Third Embodiment]
Next, the third embodiment will be described, but the description similar to that of the first embodiment will be omitted or simplified. In addition, the same number is attached | subjected to the structure similar to 1st Embodiment.

In the third embodiment, the heat dispersion layer does not have a pad portion.
In the third embodiment, as shown in FIG. 7, the heat dispersion layer 61 has a rectangular shape in plan view, and the heat generation layer 13 (and hence the heat generation pattern 47) is disposed in the heat dispersion layer 61. Yes.

That is, the outer periphery of the heat dispersion layer 61 and the upper, lower, left, and right outer peripheries of the heat generating layer 13 are arranged to coincide.
Although FIG. 7 does not describe a configuration for supplying power to the heat generating layer 13, for example, vias and internal wiring layers connected to the pair of end portions 13a and 13b so as to avoid the heat dispersion layer. May be formed.

The third embodiment also has the same effect as the first embodiment.
[4. Experimental example]
Next, experimental examples 1 to 4 performed for confirming the effects of the respective configurations of the present invention will be described.

In the following Experimental Examples 1 to 4, the heat state (that is, the temperature distribution) of the ceramic substrate was examined when the heat generating layer was heated by computer simulation.
<Experimental example 1>
In this Experimental Example 1, the thermal uniformity in each heating zone was examined.

  In Experimental Example 1, as a model of the ceramic heater used in the experiment, as shown in FIG. 8A, three heating zones (segments) having the same shape are continuously arranged in the left-right direction and one heating is performed. In the zone, a reference model having one meandering heat generation pattern was set. In this reference model, no heat dispersion layer is set.

  Specifically, in each heating zone, a model having 10 lines extending in the vertical direction in the figure and arranged in parallel at equal intervals in the horizontal direction was set. In addition, the part extended in an up-down direction among heat_generation | fever patterns is called a line.

  Then, in this reference model, the heat generation state was adjusted in order from the left line among the lines arranged in the left-right direction, such as “HCCCHHCC. . Note that H indicates heat generation and C indicates non-heat generation. In other words, two adjacent lines are considered as one set in the left-right direction (however, only one line at the left end generates heat), “two lines do not generate heat, two lines generate heat, two lines do not generate heat, etc.” Were set sequentially.

  Specifically, in such a heat generation state, the heat generation amount was adjusted in the reference model so that the temperature difference (segment temperature difference) was 1.50 ° C. or more in one heating zone. That is, the temperature of each line generating heat was adjusted.

  The state is shown in the upper part of FIG. 8B, and it can be seen that the heat-generating part and the non-heat-generating part are clearly separated, and the heat uniformity is not sufficient. In the upper diagram of FIG. 8B, the level of temperature is indicated by the type (pattern) of hatching. That is, the pattern of the six blocks in the lower diagram of FIG. 8B indicates the temperature level, and the higher the temperature is on the right side of the diagram, the higher the temperature. In addition, about the temperature which this pattern shows, the drawing which shows another heat_generation | fever state is also the same.

In addition, the heat generation state of each line so that the heat generation state shown in FIG.
Next, in the reference model described above, as shown in FIG. 9A, each rectangular heat dispersion layer (that is, three heat dispersion layers: FIG. 9) overlaps with each heat generation pattern of each heating zone. A model of Example A of the present invention in which (a) gray part) was arranged was set. The invention example A is a model corresponding to the third embodiment.

  Then, the model of Invention Example A was heated under the exothermic test condition 1 in the reference model. The result is shown in FIG. 9B, and the temperature difference within the segment is 1.16 ° C. or less, and it is understood that the heat uniformity in each heating zone is excellent.

  Next, in the reference model described above, as shown in FIG. 9C, one rectangular heat dispersion is provided so as to include between the heating zones and overlap all the heat generation patterns of all the heating zones. The model of the comparative example 1 which has arrange | positioned the layer (refer the gray part of FIG.9 (c)) was set.

  And the model of the comparative example 1 was heated on the heat_generation | fever test condition 1 in the said reference | standard model. The result is shown in FIG. 9 (d), and it can be seen that the temperature difference within the segment is 1.13 ° C. or less and that the heat uniformity is excellent (the heat separation property described later is inferior).

  Next, in the above-described reference model, as shown in FIG. 9E, for each heat generation pattern in each heating zone, two rectangular heat dispersion layers (total of six heat dispersion layers: The model of the comparative example 2 which has arrange | positioned the gray part of FIG.9 (e) was set.

  And the model of the comparative example 2 was heated on the heat_generation | fever test condition 1 in the said reference | standard model. The result is shown in FIG. 9 (f), and it can be seen that the temperature difference within the segment is 1.41 ° C., which is inferior to Example A of the present invention.

  The results of Experimental Example 1 are collectively shown in FIG. As is apparent from FIG. 10, it can be seen that the example A of the present invention is superior to the reference model and the comparative example 2 with respect to the thermal uniformity.

<Experimental example 2>
In Experimental Example 2, the heat separability between the heating zones was examined.
The reference model of Experimental Example 2 is the same as that of Experimental Example 1 as shown in FIG.

  In this reference model, all the heating patterns in the left and right heating zones among the three heating zones are heated, and all the heating patterns in the central heating zone are not heated.

  Specifically, in the reference model, the amount of heat generated was adjusted so that the temperature difference (temperature difference between segments) between the heating zone that generated heat and the heating zone that did not generate heat was 2.0 ° C. or more (specifically 2.19 ° C.). . The state is shown in FIG. In addition, the heat generation state of the heat generation pattern as shown in FIG.

  Next, in the reference model described above, as shown in FIG. 12A, each heat dispersion layer (that is, three heat dispersion layers: FIG. 12) is formed in a rectangular shape so as to overlap each heat generation pattern of each heating zone. A model of Example A of the present invention in which (g) (gray portion) is arranged was set.

  Then, the model of Invention Example A was heated under the exothermic test condition 2 in the reference model. The result is shown in FIG. 12 (b). The temperature difference between segments is 2.11 ° C., and it can be seen that the heat separability between the heating zones is excellent.

  Next, in the reference model described above, as shown in FIG. 12 (c), one heat distribution is formed in a rectangular shape so as to include between the heating zones and overlap all the heat generation patterns of all the heating zones. The model of the comparative example 1 which has arrange | positioned the layer (refer the gray part of FIG.12 (c)) was set.

  And the model of the comparative example 1 was heated on the heat_generation | fever test condition 2 in the said reference | standard model. The result is shown in FIG. 12 (d), and the temperature difference between segments is 1.60 ° C., which indicates that the heat separability is lower than that of Example A of the present invention.

  Next, in the above-described reference model, as shown in FIG. 12E, two rectangular heat dispersion layers (that is, three heat dispersion layers: FIG. The model of Comparative Example 2 in which the gray portion of 12 (e) was disposed was set.

  And the model of the comparative example 2 was heated on the heat_generation | fever test condition 2 in the said reference | standard model. The result was the same as in FIG. 12B, and the heat separability was excellent (as described above, the thermal uniformity was inferior to that of Example A of the present invention).

  The results of Experimental Example 2 are collectively shown in FIG. As is apparent from FIG. 13, it can be seen that the invention example A is superior to the reference model and the comparative example 1 in terms of heat separability.

In addition, the dashed-dotted line which shows the both ends of the temperature totaling range of FIG. 13 has shown that the temperature was measured in the position of the dashed-dotted line in each segment.
<Experimental example 3>
In this Experimental Example 3, the thermal uniformity and heat separation at the position in the thickness direction of the heat dispersion layer were examined.

  As shown in FIG. 14A, as Example B of the present invention (where the heat generating layer and the heat dispersive layer have a planar shape corresponding to the third embodiment), a heat dispersive layer is provided between the heat generating layer and the back surface. The first distance t1 was set to 0.356 mm, and the second distance t2 was set to 0.844 mm. That is, t1 <t2.

The thickness of the ceramic substrate was 2.4 mm, and the distance from the surface to the heat generating layer was 1.2 mm.
In Invention Example B, as shown in FIG. 8A of Experimental Example 1, three heating zones were set and a heat generation pattern was set in the same manner. In FIG. 14 (a), only two heating zones are shown.

  The model of Invention Example B was heated under the heat generation test condition 1. The result is shown in FIG. 14B, and the temperature difference within the segment is 1.16 ° C. or less, and it can be seen that the heat uniformity in each heating zone is excellent.

  In addition, the model of Invention Example B was heated under the exothermic test condition 2. The result is shown in FIG. 14 (c), and the temperature difference between segments is 2.11 ° C., and it can be seen that the heat separability between the heating zones is excellent.

  On the other hand, as shown in FIG. 15 (a), the present invention example C (note that the planar shape of the heat generation layer and the heat dispersion layer is the same as that of the present invention example B) is provided with a heat dispersion layer between the heat generation layer and the back surface. The first distance t1 was set to 0.800 mm, and the second distance t2 was set to 0.400 mm. That is, t1> t2.

  In Example C of the present invention, as shown in FIG. 8A of Experimental Example 1, three heating zones were set and a heat generation pattern was set in the same manner. In FIG. 15A, only two heating zones are shown.

  Then, the model of Invention Example C was heated under the exothermic test condition 1. The result is shown in FIG. 15 (b), and the temperature difference in the segment is 1.40 ° C. or less, and the heat uniformity in each heating zone is slightly inferior to that of Example B of the present invention, but the heat uniformity is high. I understand that.

  Further, the model of Invention Example C was heated under the exothermic test condition 2. The result is shown in FIG. 15 (c), and the temperature difference between segments is 2.14 ° C., and it can be seen that the heat separation between the heating zones is excellent.

  The results of Experimental Example 3 are collectively shown in FIGS. 16 (a) and 16 (b). As can be seen from FIG. 16, Example B of the present invention is excellent in both heat uniformity and heat separation. In addition, Invention Example C is slightly inferior in heat uniformity as compared with Invention Example B.

<Experimental example 4>
FIG. 17A shows a state where the heat generation layer and the heat dispersion layer are overlaid in the first embodiment corresponding to Example D of the present invention.

  The model of Invention Example D used in Experimental Example 4 was sandwiched between double circles (see FIG. 17 (b)) in the model (Invention Example A) as shown in FIG. 9 (a). It is assumed that the belt-like region has no heat dispersion layer (that is, corresponds to the first embodiment).

  The model of Invention Example D was heated under the heat generation test condition 1. The result is shown in FIG. 17B, and the temperature difference in the segment is 1.26 ° C. or less, and it is understood that the heat uniformity in each heating zone is excellent.

  FIG. 18A shows a state in which the heat generation layer and the heat dispersion layer in Comparative Example 3 are overlaid. In Comparative Example 3, a part of the heat generating layer (that is, the left corner portion of the drawing in each heating zone) is not overlapped with the heat dispersion layer.

  The model of Comparative Example 3 used in Experimental Example 4 is a rectangular heat dispersion so as to correspond to the shape of FIG. 18 (a) in the model (Example A) of the model shown in FIG. 9 (a). The lower left of the layer is cut out and recessed in an L shape, and there is no heat dispersion layer in that portion. However, in FIG. 18B, it is assumed that there is a heat dispersion layer in the circle in the recessed portion.

  And the model of the comparative example 3 was heated on the said heat_generation | fever test condition 1. FIG. The result is shown in FIG. 18B, and the temperature difference within the segment is 1.44 ° C. or more, and it is understood that the heat uniformity in each heating zone is inferior to that of Examples A and D of the present invention.

The results of Experimental Example 4 are collectively shown in FIG. FIG. 19 also shows the state of the temperature distribution in the heat generation test condition 1 of the invention example A described above.
As can be seen from FIG. 19, Invention Examples A and D are superior in heat uniformity as compared with Comparative Example 3.

<Summary of experimental examples>
FIG. 20 collectively shows the results of Experimental Examples 1 to 4. In FIG. 20, the shape of each model used in each experiment is not the shape of each model used in each experiment, but the actual heat generation layer and heat of each embodiment etc. corresponding to each model so that the characteristics due to the arrangement of the heat generation layer and the heat dispersion layer are easy to understand. The shape of the dispersion layer is shown. Regarding the thermal uniformity, the result of the largest temperature difference among the temperature differences in the segments of Experimental Examples 1 to 4 was shown.

In FIG. 20, “X” indicates that the performance is low, “Δ” indicates that the performance is higher than “X”, and “◯” indicates that the performance is higher than “Δ”.
As is apparent from Experimental Examples 1 and 2 of FIG. 20, Example A of the present invention (configuration corresponding to the third embodiment) is excellent in heat uniformity and heat separation. On the other hand, in the reference model and Comparative Examples 1 and 2, which are not the present invention, either the soaking property or the heat separation property is inferior to that of the Invention Example A.

  As is apparent from Experimental Example 3 of FIG. 20, Example B of the present invention (configuration corresponding to the third embodiment) is excellent in heat uniformity and heat separation. In addition, it can be seen that Example C of the present invention is excellent in heat separability. The soaking property of Invention Example C is superior to that of Comparative Example 2.

As is apparent from Experimental Example 4 in FIG. 20, Example D of the present invention (configuration corresponding to the first embodiment) is excellent in heat uniformity and heat separation. On the other hand, in Comparative Example 3, which is not the present invention, the thermal uniformity is inferior to that of Inventive Example D.
[5. Other Embodiments]
It goes without saying that the present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the present invention.

(1) As the outer peripheral shape of the heat dispersion layer, a shape along the outer periphery of the heat generating layer such as a rectangular shape or a circular shape can be adopted.
(2) Although it is desirable that the heat dispersion layer be on the heat generation layer side from the center between the heat generation layer and the back surface, it may be located at the center between the heat generation layer and the back surface, or closer to the back side than the center.

  (3) In the above-described embodiment, each heat generation pattern is arranged on the inner side of the heat generation layer at a predetermined distance from the outer periphery of each heat dispersion layer in plan view. The outer periphery of the heat dispersion layer may overlap in plan view. Further, each heat generation pattern may be arranged outside the outer periphery of each heat dispersion layer by a predetermined distance in a plan view as long as the effect of heat separation is obtained.

  (4) Although it is desirable that the heat dispersion layer is also disposed in a region between adjacent heat generation patterns in plan view, as shown in FIG. ) May be formed so as to enter between adjacent heat generation patterns.

(5) Further, the ceramic heater is not limited to the electrostatic chuck but can be used for other applications such as a vacuum chuck.
(6) Furthermore, the present invention can be applied to an electrostatic chuck that does not include a metal base. That is, the present invention can also be applied to an electrostatic chuck provided with an adsorption electrode and a plurality of heat generation layers in a ceramic heater.

  (7) The present invention can also be applied to a ceramic heater alone that is not an electrostatic chuck or the like. For example, the present invention can be applied to a ceramic heater provided with a plurality of heat generation layers similar to those in the above embodiments in a ceramic substrate.

  (8) In addition, the function which one component in the said embodiment has may be shared by a some component, or the function which a some component has may be exhibited by one component. Moreover, you may abbreviate | omit a part of structure of the said embodiment. In addition, at least a part of the configuration of the embodiment may be added to or replaced with the configuration of the other embodiments. In addition, all the aspects included in the technical idea specified from the wording described in the claims are embodiments of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Electrostatic chuck 5 ... Ceramic heater 13 ... Heat generating layer 15, 51, 61 ... Heat dispersion layer 15a, 51a, 51b ... Pad part 15b, 51c ... Main heat dispersion part 17 ... Ceramic substrate 40 ... Terminal part

Claims (5)

In the ceramic heater in which a plurality of heat generating layers that generate heat by energization are arranged along the plane direction inside the ceramic substrate having the front surface and the back surface,
Inside the ceramic substrate, a heat dispersion layer having a higher thermal conductivity than the ceramic material constituting the ceramic substrate is disposed for each of the heat generation layers between the heat generation layer and the back surface.
In a plan view of the ceramic substrate viewed from the thickness direction,
The heat generating layer has a linear heat generating pattern, and the heat generating pattern has a bent portion.   The heat dispersion layer is also disposed in a region between linear heat generation patterns arranged adjacent to each other in the heat generation patterns in each of the heat generation layers in the plan view. Item 2. The ceramic heater according to Item 1.   3. The ceramic heater according to claim 1, wherein a first distance between the heat generation layer and the heat dispersion layer is shorter than a second distance between the heat dispersion layer and the back surface. The heat dissipating layer has a conductive main part having a conductive pad part having a larger area than the pad part and a space between the pad part and surrounding the entire periphery of the pad part in plan view. A heat dispersion part,
A first via that electrically connects the pad portion and the heat generating layer; and a second via that electrically connects the heat generating layer and the main heat dispersing portion;
The pair of terminal portions for supplying power to the heat generating layer are electrically connected to the pad portion and the main heat dispersion portion, respectively. Ceramic heater. The heat dispersion layer has a pair of conductive pad parts in plan view and a conductive area that has a larger area than the pad parts and is spaced from the pad parts and surrounds the entire circumference of the pad parts. A main heat dispersion part having,
The heat generating layer is electrically connected to the pair of pad portions;
The ceramic heater according to any one of claims 1 to 3, wherein a pair of terminal portions for supplying power to the heat generating layer are electrically connected to the pair of pad portions, respectively.