JP7050455B2 - Manufacturing method of electrostatic chuck - Google Patents

Description

The present invention relates to a ceramic heater capable of heating a workpiece such as a semiconductor wafer, an electrostatic chuck provided with the ceramic heater, and a method for manufacturing the ceramic heater.

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 improve the accuracy of this dry etching, it is necessary to securely fix the semiconductor wafer, so an electrostatic chuck that fixes the semiconductor wafer by electrostatic attraction is used as a fixing means for fixing the semiconductor wafer. There is.

In this electrostatic chuck, for example, an adsorption electrode is provided in the ceramic substrate, and the semiconductor wafer is placed on the upper surface (adsorption surface) of the ceramic substrate by using the electrostatic attraction generated when a voltage is applied to the adsorption electrode. ). In the electrostatic chuck, for example, a metal base, which is a cooling substrate, is bonded to the lower surface (joining surface) of the ceramic substrate.

Further, some electrostatic chucks have a function of adjusting (heating or cooling) the temperature of the semiconductor wafer adsorbed on the adsorption surface (see Patent Document 1). For example, there is a technique of arranging a heating element in a ceramic substrate and heating the ceramic substrate by the heating element to heat a semiconductor wafer on a suction surface.

The heating element described above is a resistance heating element that is made of, for example, tungsten and generates heat when energized. The ceramic substrate provided with this heating element is referred to as a ceramic heater.
Further, in recent years, the demand for variation in the resistance value of the heating element of the electrostatic chuck has become stricter. For example, the required range of variation in resistance value is ± 15%, ± 10%, ± 5%, ± 3%, and the requirements are becoming stricter in sequence.

By the way, when a heating element is produced, a heating pattern is formed by metallizing printing and then fired. Therefore, the resistance value of the heating element after firing is estimated from the thickness and width of the heating pattern before firing. However, since the resistance value of the heating element fluctuates depending on the firing state, the actual resistance value may deviate from the estimated resistance value.

As a countermeasure, a method of firing with the heat generation pattern exposed on the surface of the substrate and then irradiating the exposed heating element with laser light to adjust the resistance value (that is, a method of adjusting the resistance value by trimming). ) Has been proposed (see Patent Document 2).

Japanese Unexamined Patent Publication No. 2016-001757 International Publication No. 2002/043441

However, the above-mentioned conventional technique is not always sufficient, and further improvement is required.
Specifically, in the technique of trimming a heating element exposed on the substrate surface to adjust the resistance value of the heating element, after trimming, a ceramic substrate for other coating is attached so as to cover the heating element exposed on the substrate surface. It is necessary to attach it, but depending on the adhesive used for attaching, there may be a problem in the durability of the ceramic heater.

For example, when the ceramic heater is used in a plasma atmosphere, there is a problem that the adhesive is deteriorated by the plasma and the durability of the ceramic heater is lowered.
Further, due to the difference in thermal conductivity between the ceramic substrate and the adhesive, a thermal gradient may be generated depending on the coating state of the adhesive, and the temperature distribution of the ceramic heater may be deteriorated.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a ceramic heater, an electrostatic chuck, and a method for manufacturing a ceramic heater, which have high durability and can suppress deterioration of the temperature distribution of the ceramic heater. To do.

(1) The first aspect of the present invention relates to a ceramic heater in which a resistance heating element that generates heat by energization is arranged inside a ceramic substrate.
The ceramic substrate of this ceramic heater has an opening from one main surface to the resistance heating element, and inside the opening, the thermal conductivity is the same as that of the ceramic substrate or higher than the thermal conductivity of the ceramic substrate. A sealing material having a high rate and made of at least one of ceramics and resin is arranged.

As described above, in the first aspect, since the ceramic substrate has an opening extending from one main surface to the resistance heating element, before arranging the sealing material, the ceramic substrate is viewed from the outside of the ceramic heater. The resistance value of the resistance heating element can be adjusted by removing a part of the resistance heating element through the opening (that is, by trimming).

That is, the resistance value of the resistance heating element can be adjusted accurately by, for example, irradiating the resistance heating element with a laser beam through the opening to remove a part of the resistance heating element.
Further, when the above-mentioned trimming is performed, the resistance value of the entire resistance heating element increases, and the remaining trimmed portion, for example, the portion where the width of the resistance heating element is narrowed by trimming (hereinafter referred to as the trimming remaining portion). The resistance value of is increased. Therefore, when energized, the temperature of the remaining trimming portion tends to rise as compared with the temperature of the other portions.

On the other hand, in the first aspect, the opening is sealed with at least one of ceramics and resin, which has the same thermal conductivity as that of the ceramic substrate or has a higher thermal conductivity than the thermal conductivity of the ceramic substrate. Since the material is arranged, even if the temperature of the trimming residue of the resistance heating element rises, the heat of that part is quickly conducted to other parts by the encapsulant having high thermal conductivity arranged in the opening. Be (ie, heat drawn).

Therefore, the temperature difference between the opening in which the sealing material is arranged and the surrounding portion thereof becomes small. That is, even when trimming is performed, there is an effect that the temperature distribution in the plane direction of the ceramic heater becomes small (that is, the soaking property is improved).
Further, in the first aspect, the ceramic substrate provided with the heating element on the surface and another ceramic substrate are not joined by an adhesive so as to cover the entire heating element. Therefore, there is an advantage that the adhesive is not deteriorated by plasma during use of the ceramic heater (for example, during processing by plasma), so that the durability is high.

The ceramics and resins used as the material of the encapsulant used in the first aspect have higher durability such as plasma resistance than the conventional adhesives used for joining the above-mentioned ceramic substrates.

(2) In the second aspect of the present invention, the resistance heating element may have a linear portion having a predetermined width in a plan view of the ceramic substrate from the thickness direction, and the width of the opening may be set. It may be larger than the width of the linear portion.

In the second aspect, when the width of the opening is larger than the width of the linear portion of the resistance heating element, the resistance value of the resistance heating element is adjusted by laser light or the like through the opening. It can be done easily.

In particular, by exposing the entire linear portion of the resistance heating element in the width direction in the opening, it is possible to easily confirm which portion should be deleted and how much, so that it is possible to easily confirm when trimming. It has the advantage of high workability.

(3) In the third aspect of the present invention, the encapsulant may be arranged so as to come into contact with the resistance heating element and reach the opening end of the opening.
In the third aspect, when the encapsulant is in contact with the resistance heating element, the heat is quickly released even when the temperature of the trimming residue of the resistance heating element becomes higher than in the case where the encapsulant is not in contact with the resistance heating element. Can be conducted to the surroundings.

Moreover, in the third aspect, when the encapsulant is arranged so as to reach the opening end of the opening, for example, when a metal cooling substrate is arranged on the opening end side of the opening, the trimming residue or the like is formed. Heat can be quickly conducted to the cooling substrate side.

As a result, even when trimming is performed, there is an effect that the temperature distribution in the plane direction of the ceramic heater is further reduced.
(4) The fourth aspect of the present invention is made of a metal bonded to the ceramic heater according to any one of the first to third aspects and the main surface side on which the opening of the ceramic substrate is formed so as to cover the opening. It is an electrostatic chuck equipped with a cooling substrate and.

Such an electrostatic chuck has an effect that the temperature distribution in the plane direction of the ceramic heater (hence, the electrostatic chuck) is small even when the resistance heating element of the ceramic heater is trimmed.

(5) The fifth aspect of the present invention relates to a method for manufacturing a ceramic heater according to any one of the first to third aspects.
In this method for manufacturing a ceramic heater, a ceramic substrate having an opening is processed to remove a part of the resistance heating element through the opening to adjust the resistance value of the resistance heating element.

According to the fifth aspect, the resistance value of the resistance heating element can be easily and accurately adjusted.
(6) The sixth aspect of the present invention relates to a method for manufacturing a ceramic heater according to any one of the first to third aspects.

In this method of manufacturing a ceramic heater, the resistance heating element has a plurality of parallel heating elements connected in parallel to the portion exposed at the opening, and the ceramic substrate having the opening is interposed through the opening. The resistance value of the resistance heating element is adjusted by disconnecting a part of the plurality of parallel heating elements of the resistance heating element.

According to the sixth aspect, the resistance value of the resistance heating element can be easily and accurately adjusted.
(7) In the seventh aspect of the present invention, after adjusting the resistance value, the thermal conductivity is the same as the thermal conductivity of the ceramic substrate or larger than the thermal conductivity of the ceramic substrate in the opening, and at least of the ceramics and the resin. A sealing material made of one kind may be arranged.

According to the seventh aspect, it is possible to easily manufacture a ceramic heater having a small temperature distribution in the plane direction.
(8) In the eighth aspect of the present invention, first, in the first step (first step), the first ceramic green sheet and the second ceramic green sheet laminated on the first ceramic green sheet are formed. To make.

In the next step (second step), a resistance heating element pattern made of a resistance heating element material is formed on the surface of the first ceramic green sheet.
In the next step (third step), a through hole serving as an opening is formed in the second ceramic green sheet in accordance with the position of the resistance heating element pattern on the first ceramic green sheet.

In the next step (fourth step), the second ceramic green sheet is laminated on the first ceramic green sheet so that the position of the resistance heating element pattern and the position of the through hole are aligned with each other. Form the body.

In the next step (fifth step), the laminate is fired to form a ceramic substrate having an opening.
In the eighth aspect, it is possible to easily manufacture a ceramic substrate having a resistance heating element in the ceramic substrate and an opening from the surface of the substrate to the resistance heating element in the above-mentioned process.

<Each configuration of the present invention will be described below>
The ceramic substrate is a substrate (plate-shaped member) containing ceramics as a main component (50% by mass or more). Examples of the material of the ceramics include aluminum oxide (alumina), aluminum nitride, yttrium oxide (itria) and the like.

The ceramic substrate used for the electrostatic chuck is a ceramic insulating plate having electrical insulation.
-The main surface is the surface that forms the end in the thickness direction of the plate material (board).

-The resistance heating element is a heating element that generates heat when energized, and examples of the material of the resistance heating element include tungsten, tungsten carbide, molybdenum, molybdenum carbide, tantalum, and platinum.

-As the resistance heating element, a configuration in which a plurality of resistance heating elements are arranged on the same plane along the main surface can be adopted.
-The opening includes an opening extending from the opening end so that the resistance heating element can be irradiated with light. That is, examples of the opening include an opening extending in a direction perpendicular to the main surface.

-The encapsulant made of at least one of ceramics and resin indicates a encapsulant made of ceramics, a encapsulant made of resin, and an encapsulant made of ceramics and resin.
Here, examples of the ceramics include materials of the same type as the ceramic substrate and various other materials. However, since the thermal conductivity of the encapsulant is the same as the thermal conductivity of the ceramic substrate or larger than the thermal conductivity of the ceramic substrate, a type or component satisfying the conditions is adopted.

As the ceramics, aluminum oxide (alumina), aluminum nitride, yttrium oxide (itria) and the like can be adopted. Further, as the resin, polyphenylene sulfide (PPS) or the like can be adopted.

Here, "consisting of" consisting of at least one of ceramics and resin means that it is made of a material containing ceramics as a main component (50% by mass or more) or resin as a main component (59% by mass or more). It means that it is made of a material to be used, or is made of a material containing ceramics and a resin as main components (50% by mass or more).

-As a method of adjusting the resistance value of the resistance heating element, a well-known method of trimming the resistance heating element can be adopted.
For example, a part of the resistance heating element may be removed by a laser beam or the like. For example, a part of the resistance heating element may be cut out to narrow the line width or the like, or a groove or the like may be provided on the surface to adjust the resistance value (specifically, increase the resistance value). A part of the resistance heating element may be mechanically removed.

Further, the resistance value may be adjusted by providing a plurality of parallel heat generating portions connected in parallel to the resistance heating element and cutting any (one or a plurality) of the parallel heat generating portions.
-Ceramics green sheet is a sheet formed from a material containing ceramics as a main component (that is, a sheet before firing).

It is a perspective view which shows the electrostatic chuck of 1st Embodiment. It is sectional drawing which shows the part of the electrostatic chuck of 1st Embodiment which was broken in the thickness direction. It is a top view which shows the heating region of a ceramics heater and the arrangement of a heating element. (A) is a plan view showing the heating element in the electrostatic chuck and its adjusting portion and the opening (excluding the sealing material) in an overlapping manner, and (b) is AA of FIG. 4 (a) in the electrostatic chuck. It is sectional drawing which shows the cross section. It is a flowchart which shows the manufacturing process of a ceramics heater. It is explanatory drawing which shows the manufacturing method of a ceramics heater. (A) is a plan view showing the adjustment part before trimming exposed to the opening, and (b) is a plan view showing the adjustment part of trimming exposed to the opening. (A) is an explanatory diagram showing a method of adjusting the resistance value of the ceramic heater of the second embodiment, and (b) is an explanatory diagram showing a method of adjusting the resistance value of the ceramic heater of the modified example.

[1. First Embodiment]
Here, as the first embodiment, for example, an electrostatic chuck capable of adsorbing and holding a semiconductor wafer will be taken as an example.

[1-1. Constitution]
First, the structure of the electrostatic chuck of the first embodiment will be described.
As shown in FIG. 1, the electrostatic chuck 1 of the first embodiment is a device for adsorbing a semiconductor wafer 3 which is a workpiece on the upper side of FIG. 1, and a ceramic heater 5 and a cooling substrate 7 are laminated. It is joined by the adhesive layer 9.

The upper surface (upper surface: suction surface) of the ceramic heater 5 in FIG. 1 is the first main surface A, and the lower surface is the second main surface B. Further, the upper surface of the cooling substrate 7 is the third main surface C, and the lower surface is the fourth main surface D.

Of these, the ceramic heater 5 has a disk shape and is composed of a ceramic substrate 17 provided with an adsorption electrode 11 and a heat generating portion 13.
The cooling substrate 7 is a disk-shaped metal base having a diameter larger than that of the ceramic heater 5, and is coaxially joined to the ceramic heater 5. The cooling substrate 7 is provided with a flow path (cooling passage) 19 through which a cooling fluid (refrigerant) flows in order to cool the ceramic substrate 17 (hence, the semiconductor wafer 3). As the cooling fluid, for example, a cooling liquid such as a fluoride liquid or pure water can be used.

Further, the electrostatic chuck 1 is provided with lift pin holes 21 or the like into which lift pins (not shown) are inserted at a plurality of locations 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 A side for cooling the semiconductor wafer 3.

A cooling gas hole (not shown) may be provided separately from the lift pin hole 21. 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 (hence, the ceramic substrate 17) has its second main surface B side on the third main surface C side of the cooling substrate 7 by, for example, an adhesive layer 9 made of silicone. It is joined.

The ceramic substrate 17 is a laminated body of a plurality of ceramic layers (not shown), and is an alumina-based sintered body containing alumina as a main component. The alumina-based sintered body is an insulator (dielectric material).

Inside the ceramic substrate 17, from above FIG. 2, an adsorption electrode 11, a heating element 13 including a plurality of heating elements 25, and the like are arranged.
Further, as will be described later, openings 27 are provided so as to reach the second main surface B from each heating element 25, and a sealing material 29 is arranged in each opening 27.

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 from the thickness direction, and a heating element 25 is arranged in each heating zone KZ. ing. That is, the ceramic substrate 17 has a configuration in which a plurality of heating elements 25 are arranged in a plan view. The plurality of heating elements 25 are arranged on the same plane.

Each heating element 25 is electrically connected to the power feeding terminal 31.
That is, each heating element 25 has both ends (a pair of end portions 25a and 25b) of each heating element 25 on one side of the ceramic substrate 17 via the wiring portion 33 so that the temperature can be controlled independently. (That is, on the second main surface B side), it is electrically connected to each pair of power feeding terminals 31.

The wiring portion 33 includes a via 35 extending in the vertical direction (thickness direction) of FIG. 2, an internal wiring layer 37 extending in a plane direction perpendicular to the thickness direction, a terminal pad 39, and the like as a configuration for supplying power to the heating element 25. A power supply terminal 31 is connected to the terminal pad 39. The wiring portion 33 is made of, for example, tungsten.

Further, the adsorption electrode 11 is electrically connected to a well-known electrode terminal (not shown) to which a voltage is applied.
<Cooling board>
The cooling substrate 7 is made of metal made of aluminum or an aluminum alloy. In addition to the cooling passage 19 and the lift pin hole 21, the cooling substrate 7 is formed with a through portion 41 which is a through hole in which the electrode terminal and the power supply terminal 31 are arranged.

In addition, on the fourth main surface D side of the electrostatic chuck 1, a plurality of internal holes 43 are provided so as to reach the inside of the ceramic heater 5 from the fourth main surface D in order to accommodate the power feeding terminal 31. The through portion 41 of the cooling substrate 7 constitutes a part of the internal hole 43.

Further, an insulating cylinder 45 having electrical insulation is arranged in the internal hole 43 accommodating the electrode terminal and the power feeding terminal 31.
<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 high DC voltage is applied to the adsorption electrode 11, whereby an electrostatic attraction force (adsorption force) for adsorbing the semiconductor wafer 3 is generated, and this adsorption force is generated. It is used to adsorb and fix the semiconductor wafer 3.

In addition to this, various well-known configurations (unipolar or bipolar electrodes, etc.) can be adopted for the adsorption electrode 11. The adsorption electrode 11 is made of a conductive material such as tungsten.

[1-2. Configuration of heating element]
<Arrangement of heating element>
First, the arrangement state of the heating element 25 in the plane direction will be described.

As shown in FIG. 3, a plurality of heating zones KZ are set in the ceramic substrate 17 (hence, the ceramic heater 5) in a plan view, and the temperature of each heating zone KZ is independently set in each heating zone KZ. The heating elements 25 are arranged one by one so that they can be adjusted. The planar shape of the heating element 25 is schematically shown.

Further, the number of heating zones KZ is, for example, 200 in the range of 100 or more, but is shown in a simplified manner in FIG. 3 (that is, the number of heating zones KZ is displayed in a small number). The heating element 25 is a resistance heating element made of a metal material (tungsten or the like) that generates heat when a voltage is applied and a current flows.

<Structure of heating element, opening, sealing material>
Next, the configuration of the heating element 25, the opening 27, and the sealing material 29 will be described.
As shown in FIG. 4, when the ceramic heater 5 is viewed from the second main surface B side in a plan view, the heating element 25 has a linear portion (that is, a heating portion that generates heat) 51 having a predetermined width and a linear portion. It is composed of circular ends (that is, terminal pads for heating elements) 53 at both ends, which are pads for supplying electric power to the portion 51. Further, the linear portion 51 is composed of a meandering portion 55 meandering a plurality of times on the side opposite to the end portion 53, and each lead portion 57 connecting both ends of the meandering portion 55 and each end portion 53.

In particular, in the present embodiment, each lead portion 57 is provided with a rectangular adjusting portion 59 which is a linear portion having a width wider than that of the other linear portions 51.
Note that FIG. 4A shows an adjusting unit 59 before adjusting the resistance value of the heating element 25, which will be described later.

Further, the ceramic heater 5 has an outer periphery from the adjusting portion 59 so as to reach the heating element 25 from the second main surface B (that is, along the thickness direction) and to include the adjusting portion 59 inside in a plan view. A large opening 27 (that is, a large vertical and horizontal dimension) is provided.

Then, as shown in FIG. 4B, a sealing material 29 having the same shape as the inside of the opening 27 is fitted into each opening 27 so as to seal each opening 27. There is. For example, when the opening 27 is a space in the shape of a quadrangular prism, the sealing material 29 is also a quadrangular prism (however, the shape is slightly smaller than that of the opening 27).

The encapsulant 29 has the same thermal conductivity as that of a material such as ceramics (for example, a material containing alumina as a main component) constituting the ceramic substrate 17, or has a larger thermal conductivity than the thermal conductivity of the material such as ceramics. Moreover, it is composed of at least one of ceramics and resin. Specifically, the encapsulant 29 is made of, for example, alumina or plastic. Specifically, for example, as the material of the sealing material 29, a material such as ceramics having the same composition as that of the ceramic substrate 17 can be used.

As will be described later, in addition to the method of fitting the bulk sealing material 29 into the opening 29, the material of the sealing material 29 may be filled by thermal spraying or the like and then solidified.
The sealing material 29 is in contact with a heating element 25 (specifically, an adjusting portion 59) whose tip (upper end of FIG. 4B) is exposed to the opening 27, and the rear end thereof is the second main surface B. Has reached.

[1-3. Production method]
<Overview of the manufacturing process of ceramic heaters>
First, the outline of the manufacturing process of the ceramic heater 5 will be described with reference to FIGS. 5 and 6.

(First step)
First, as shown in FIG. 6A, a first ceramic green sheet 71a and a second ceramic green sheet 71b laminated on the first ceramic green sheet are produced. The first and second ceramic green sheets 71a and 71b indicate separate ceramic green sheets, and a larger number of ceramic green sheets may be used for laminating.

(Second step)
Next, as shown in FIG. 6B, a resistance heating element pattern 26 made of a material of the resistance heating element to be the heating element 25 is formed on the surface of the first ceramic green sheet 71a.

(Third step)
Next, as shown in FIG. 6 (c), the second ceramic green sheet 71b becomes the adjusting unit 59 in detail according to the position of the resistance heating element pattern 26 on the first ceramic green sheet 71a. A through hole 27a to be an opening 27 is formed in accordance with the position of the adjustment pattern 59a.

(4th step)
Next, as shown in FIG. 6D, the position of the adjustment pattern 59a of the resistance heating element pattern 26 and the position of the through hole 27a are aligned on the first ceramic green sheet 71a so that the second position is aligned. The ceramic green sheet 71b is laminated to form a laminated body 73.

(Fifth step)
Next, as shown in FIG. 6 (e), the laminated body 73 is fired to form a ceramic substrate 17 (hence, a ceramic heater 5) having a heating element 25 and an opening 27.

(6th step)
Next, as shown in FIG. 6 (f), a part of the heating element 25 (specifically, the adjusting unit 59) is attached to the ceramic substrate 17 having the opening 27 by means of a laser beam or the like through the opening 27. The resistance value of the heating element 25 is adjusted by performing the removing process.

(7th step)
Next, as shown in FIG. 6 (g), after adjusting the resistance value, the thermal conductivity in the opening 27 is the same as the thermal conductivity of the ceramic substrate 17 or larger than the thermal conductivity of the ceramic substrate 17 and , A sealing material 29 made of at least one of ceramics and resin is arranged.

By the above-mentioned first to seventh steps, the ceramic heater 5 whose resistance value of the heating element 25 is adjusted can be obtained.
<Detailed manufacturing process of electrostatic chuck>
Next, the detailed contents (examples) of the entire manufacturing process of the electrostatic chuck 1 of the present embodiment will be described.

(1) First, as a raw material for the ceramic substrate 17, powders of Al _{2O 3} : 92% by weight, MgO: 1% by weight, CaO: 1% by weight, and SiO ₂ : 6% by weight, which are the main components, are mixed. , Wet pulverize in a ball mill for 50 to 80 hours, and then dehydrate and dry.

(2) Next, a solvent or the like is added to this powder and mixed with a ball mill to form a slurry.
(3) Next, this slurry is defoamed under reduced pressure and then poured out into a flat plate and slowly cooled to dissipate the solvent to form each alumina green sheet to be each ceramic layer. The alumina green sheet corresponds to the first and second ceramic green sheets 71a and 71b.

Then, for each alumina green sheet, a space (for example, a through hole 27a) serving as a lift pin hole 21 or an opening 27 and a through hole serving as each via 35 are opened at necessary locations.
(4) Further, tungsten powder is mixed with the raw material powder for the alumina green sheet to form a slurry, which is used as a metallized ink.

(5) Then, in order to form the adsorption electrode 11, the heating element 25, the internal wiring layer 37, the terminal pad 39, etc., the metallizing ink is used to use the metallizing ink to form the adsorption electrode 11, the heating element 25, the internal wiring layer 37, and the like. Each pattern (for example, a resistance heating element pattern 26) is printed on an alumina green sheet corresponding to the formed portion of the terminal pad 39 or the like by a normal screen printing method. In addition, in order to form each via 35, the through holes are filled with metallized ink.

(6) Next, each alumina green sheet is positioned and thermocompression bonded so that necessary spaces such as a lift pin hole 21 and an opening 27 are formed to form a laminated sheet (that is, a laminated body 73). ..

(7) Next, the thermocompression-bonded laminated sheet (that is, the laminated body 73) is cut into a predetermined shape (that is, a disk shape).
(8) Next, the cut laminate 73 is fired (mainly fired) in a reducing atmosphere in a range of 1400 to 1600 ° C. (for example, 1550 ° C.) for 5 hours to prepare an alumina-like sintered body.

(9) Then, after firing, the alumina-based sintered body is subjected to necessary processing such as processing on the first main surface A side to produce a ceramic substrate 17.
(10) Next, a terminal fitting (not shown) is brazed to the terminal pad 39 on the second main surface B of the ceramic substrate 17. The terminal fitting is electrically connected to the end portion 53 of the heating element 25.

(11) Next, the heating element 25 is trimmed through the opening 27 of the ceramic substrate 17 as described later to adjust the resistance value of the heating element 25.
The trimming may be performed after the firing, or may be performed after the cooling substrate 7 is joined. However, when trimming is performed after joining the cooling substrate 7, it is necessary to provide the cooling substrate 7 with a through hole (that is, a through hole communicating with the opening 27) capable of trimming.

(12) Next, after trimming, the sealing material 29 is fitted into the opening 27 of the ceramic substrate 17. The sealing material 29 is manufactured by firing a ceramic material in advance so that the shape of the space of the opening 27 is formed, and appropriately processing the surface.

(13) Separately, the cooling substrate 7 is manufactured. Specifically, the cooling substrate 7 is formed by cutting a metal plate or the like.
(14) Next, the cooling substrate 7 and the ceramic substrate 17 are joined and integrated. That is, the cooling substrate 7 and the ceramic substrate 17 are joined by closing the opening 27 side of the ceramic substrate 17 with the cooling substrate 7.

(15) Next, the power feeding terminal 31 and the like are arranged to complete the electrostatic chuck 1.
<How to adjust the resistance value of the heating element>
Here, a method of adjusting the resistance value of the heating element 25 will be described in detail.

As shown in FIG. 7A, the adjusting portion 59 of the heating element 25 is exposed in the opening 27 of the ceramic substrate 17. The width of the opening 27 (the width in the left-right direction in the figure) is larger than the width of the adjusting portion 59 of the heating element 25 for trimming.

Therefore, as shown in FIG. 7B, the resistance value of the heating element 25 is increased by, for example, irradiating the adjusting unit 59 with a laser beam through the opening 27 to remove a part of the adjusting unit 59. adjust. For example, the width of the adjusting portion 59 is processed to be narrowed to increase the resistance value of the heating element 25.

Specifically, if you investigate in advance by experiments etc. how much the width should be narrowed to increase the resistance value of the heating element 25, you can know how narrow the width should be, so at first , Based on that finding, narrow the width. At first, make the width slightly thicker so as not to make it too narrow.

Next, at that stage, for example, the terminals of the tester are brought into contact with the terminal fittings connected to the ends 53 at both ends of the heating element 25, and the resistance value of the heating element 25 is measured. After that, the width is slightly narrowed according to the measured resistance value, and the resistance value is measured again. By repeating such work, the resistance value can be adjusted to the desired value with high accuracy.

[1-4. effect]
Next, the effect of the first embodiment will be described.
(1) In the first embodiment, since the ceramic substrate 17 is formed with an opening 27 extending from the second main surface B to the heating element 25, the ceramics are formed before the sealing material 29 is arranged. Adjusting the resistance value of the heating element 25 from the outside of the heater 5 by removing a part of the heating element 25 (specifically, the adjusting unit 59) from the outside through the opening 27 (that is, by trimming). Can be done.

That is, the resistance value of the heating element 25 can be adjusted accurately by, for example, irradiating the heating element 25 with a laser beam through the opening 27 and removing a part of the adjusting unit 59.
Further, when the above-mentioned trimming is performed, the resistance value of the entire heating element 25 increases, and the resistance of the remaining trimmed portion, that is, the portion where the width of the heating element 25 is narrowed by the trimming (that is, the trimming remaining portion). The value goes up. Therefore, when energized, the temperature of the remaining trimming portion tends to rise as compared with the temperature of the other portions.

On the other hand, in the first embodiment, the opening 27 has the same thermal conductivity as that of the ceramic substrate 17, or has a larger thermal conductivity than the thermal conductivity of the ceramic substrate, and is made of at least one of ceramics and resin. Since the encapsulant 29 is arranged, even if the temperature of the trimming residue of the heating element 25 rises, the encapsulant 29 having a high thermal conductivity arranged in the opening 27 quickly heats the portion. Is conducted elsewhere (ie, heat drawn).

Therefore, the temperature difference between the opening 27 in which the sealing material 29 is arranged and the surrounding portion thereof becomes small. That is, even when trimming is performed, there is an effect that the temperature distribution of the ceramic heater 5 in the plane direction becomes small (that is, the soaking property is improved).
Further, in the first embodiment, the ceramic substrate provided with the heating element on the surface and another ceramic substrate are not joined by an adhesive so as to cover the entire heating element. Therefore, there is an advantage that the adhesive is not deteriorated by plasma during use of the ceramic heater 5 (for example, during processing by plasma), so that the durability is high.

(2) In the first embodiment, the heating element 25 has a linear portion (for example, an adjusting portion 59) having a predetermined width in a plan view, and the width of the opening 27 is a line for trimming. It is larger than the width of the shaped part.

Therefore, the resistance value of the heating element 25 can be easily adjusted by a laser beam or the like through the opening 27 which is larger than the width of the linear portion of the heating element 25.
In particular, the entire linear portion of the heating element 25 (that is, the adjusting portion 59) in the width direction is exposed in the opening 27. Therefore, it is possible to easily confirm which part should be deleted and how much, so that there is an advantage that workability at the time of trimming is high.

(3) In the first embodiment, the sealing material 29 is arranged so as to come into contact with the heating element 25 and reach the opening end of the opening 27.
That is, since the sealing material 29 is in contact with the heating element 25, even if the temperature of the trimming balance of the heating element 25 becomes high, the heat can be quickly conducted to the surroundings.

Moreover, since the sealing material 29 is arranged so as to reach the opening end of the opening 27, and the metal cooling substrate 7 is arranged on the opening end side of the opening 27, the heat of the trimming portion is quickly dissipated. It can be conducted to the cooling substrate 7 side.

As a result, even when trimming is performed, there is an effect that the temperature distribution in the plane direction of the ceramic heater 5 becomes smaller.
(4) In the first embodiment, the ceramic heater 5 (hence, the electrostatic chuck 1) having the above-mentioned excellent performance can be easily manufactured by the first to seventh steps.

[1-5. Correspondence of words]
Ceramic substrate 17, heating element 25, ceramic heater 5, opening 27, sealing material 29, adjusting unit 59, cooling substrate 7, electrostatic chuck 1, first ceramics green sheet 71a, first embodiment of the first embodiment. The ceramic green sheet 71b, the resistance heating element pattern 26, the through hole 27a, and the laminated body 73 of No. 2 are the ceramic substrate, the resistance heating element, the ceramic heater, the opening, the sealing material, the linear portion, and the cooling, respectively, of the present invention. It corresponds to an example of a substrate, an electrostatic chuck, a first ceramic green sheet, a second ceramic green sheet, a resistance heating element pattern, a through hole, and a laminated body.
[2. Second Embodiment]
Next, the second embodiment will be described, but the same contents as those of the first embodiment will be omitted or simplified. The same number is assigned to the same configuration as that of the first embodiment.

Since the method for adjusting the resistance value of the heating element is different from that of the first embodiment in the second embodiment, the method for adjusting the resistance value of the heating element in the second embodiment will be described.
First, the configuration of the heating element in the second embodiment will be described.

As shown in FIG. 8A, when the ceramic heater 5 is viewed from the second main surface B side in a plan view, the heating element 81 is a linear portion (that is, a heat generating portion) 83 having a predetermined width and a linear portion 83. It is composed of circular ends (that is, terminal pads for heating elements) 85 at both ends. Further, the linear portion 83 is composed of a meandering portion 87 meandering a plurality of times on the side opposite to the end portion 85, and each lead portion 89 connecting both ends of the meandering portion 87 and each end portion 85.

In particular, in the second embodiment, in the meandering portion 87, the first parallel portion 91 and the second parallel portion 93 are arranged in order from one end 85 side to the other end 85 side. There is. That is, the first parallel portion 91 and the second parallel portion 93 are electrically connected in series.

Of these, in the first parallel section 91, the linear first parallel heating section 101 and the linear second parallel heating section 103 are electrically connected in parallel. Further, in the second parallel unit 93, the linear third parallel heat generating unit 105 and the linear fourth parallel heat generating unit 107 are electrically connected in parallel.

Then, in the ceramic heater 5, a first opening 109 having a rectangular shape in a plan view is provided so as to reach the first parallel heat generating portion 101 of the heating element 81 from the second main surface B (that is, along the thickness direction). It is provided. The first opening 109 has an opening dimension (vertical dimension in FIG. 8A) larger than the line width of the first parallel heat generating portion 101 (vertical dimension in FIG. 8A). Before trimming, the entire first parallel heat generating portion 101 (the entire width direction) is exposed in the first opening 109.

The dimension in the left-right direction of FIG. 8A of the first opening 109 is set to be smaller than the dimension in the longitudinal direction of the first parallel heat generating portion 101 (hereinafter, other second to fourth described later). The same applies to the openings 111, 113, 115).

Similarly, the ceramic heater 5 is provided with a rectangular second opening 111 such that the second parallel heat generating portion 103 is exposed. The second opening 111 has an opening dimension larger than the line width of the second parallel heat generating portion 103, and before trimming, the second opening 111 has the entire second parallel heat generating portion 103 ( The whole in the width direction) is exposed.

Similarly, the ceramic heater 5 is provided with a rectangular third opening 113 so that the third parallel heat generating portion 105 is exposed. The third opening 113 has an opening dimension larger than the line width of the third parallel heat generating portion 105, and before trimming, the third opening 113 has the entire third parallel heat generating portion 105 ( The whole in the width direction) is exposed.

Similarly, the ceramic heater 5 is provided with a rectangular fourth opening 115 such that the fourth parallel heat generating portion 107 is exposed. The fourth opening 115 has an opening dimension larger than the line width of the fourth parallel heat generating portion 107, and before trimming, the fourth opening 115 has the entire fourth parallel heating portion 107 ( The whole in the width direction) is exposed.

Therefore, the resistance value of the heating element 81 is adjusted by, for example, irradiating the parallel heating elements 101 to 107 to which the laser light is to be cut through the openings 109 to 115 to cut the parallel heating elements 101 to 107. can do.

Next, a modified example of the second embodiment will be described.
In the second embodiment, each opening 109 to 115 is provided for each parallel heat generating portion 101 to 107, but as shown in FIG. 8B, a plurality of parallel heat generating portions are surrounded by one opening. May be provided with an opening.

Specifically, the first opening 121 is provided so as to surround the first and second parallel heat generating portions 101 and 103, and the second opening 123 is provided so as to surround the third and fourth parallel heat generating portions 105 and 107. May be provided.
[3. Other embodiments]
It should be noted that the present invention is not limited to the above-described embodiment or experimental example, and it goes without saying that the present invention can be carried out in various embodiments without departing from the present invention.

(1) The number of heating elements arranged on the ceramic substrate may be one or more.
(2) One or more openings may be provided for one heating element.

(3) When there are a plurality of heating elements, it is preferable to provide an opening for each heating element, but some heating elements may not be provided with an opening.
(4) When a plurality of openings are provided according to one or a plurality of heating elements, it is preferable to arrange the sealing material in all the openings, but even if there is an opening in which the sealing material is not arranged. good.

(5) When there are a plurality of heating elements and each encapsulant is provided with an opening, the thermal conductivity of each encapsulant may be different, for example, the encapsulant is sealed according to the trimming state. You can select the type of material.

For example, if there is a lot of trimming (ie, if the amount of heating element removed is large and therefore the temperature of the rest of the trimming is high), a sealing material with high thermal conductivity is used, while less trimming (that is, if there is less trimming). That is, when the amount of removing the heating element is small, and therefore the temperature rise of the trimming residue is small), a sealing material having a smaller thermal conductivity may be used.

(6) As the sealing material, a solid ceramic member, a resin member, a composite member made of ceramics and a resin can be adopted. In this case, a sealing material corresponding to the hole shape of the opening may be prepared, and after trimming, the sealing material may be pushed into the opening.

The shape of the encapsulant is not limited to the square column as in the above embodiment, and may be any shape as long as it reaches the resistance heating element from one of the ceramic substrates such as a polygonal column and a cylinder.
Further, a sealing material for a solid ceramic member, a resin member, or a composite member may be used in combination with a sealing material having fluidity such as cement or resin and solidifying after sealing. As a result, even if the outer shape of the ceramic member, the resin member, or the composite member is slightly different from the shape of the opening, the sealing material can be filled in the opening without a gap.

Alternatively, instead of using a solid ceramic member, a resin member, or a sealing material for a composite member, a sealing material having fluidity such as cement or resin and solidifying after sealing may be used. For example, a material having fluidity may be used to fill the opening by thermal spraying or the like, and then solidified to form a sealing material.

(7) The function of one component in each of the above embodiments may be shared by a plurality of components, or the function of the plurality of components may be exerted by one component. Further, a part of the configuration of each of the above embodiments may be omitted. Further, at least a part of the configuration of each of the above embodiments may be added or substituted with respect to the configuration of another embodiment. It should be noted that all aspects included in the technical idea specified from the wording described in the claims are embodiments of the present invention.

1 ... Electrostatic chuck 5 ... Ceramic heater 7 ... Cooling substrate 17 ... Ceramic substrate 25, 81 ... Heating element 26 ... Resistance heating element pattern 27, 109, 111, 113, 115, 121, 123 ... Opening 27a ... Through hole 29 ... Encapsulant 59 ... Adjustment part 63 ... Laminated body 71a ... First ceramic green sheet 71b ... Second ceramic green sheet 101, 103, 105, 107 ... Parallel heating element

Claims (5)

In a method for manufacturing an electrostatic chuck equipped with a ceramic heater in which a resistance heating element that generates heat by energization is arranged inside a ceramic substrate.
The ceramic substrate has an opening extending from one main surface to the resistance heating element, and the inside of the opening has the same thermal conductivity as the ceramic substrate or from the thermal conductivity of the ceramic substrate. A sealing material having high thermal conductivity and made of at least one of ceramics and resin is arranged.
The resistance heating element has a portion in which the resistance value is adjusted within the range of the opening in a plan view of the ceramic substrate from the thickness direction.
A cooling substrate joined so as to cover the opening is provided on the one main surface side of the ceramic substrate on which the opening is formed.
The encapsulant comes into contact with the resistance heating element, is arranged so as to reach the opening end of the opening, and reaches an adhesive layer provided between the ceramic substrate and the cooling substrate. Arranged like ,
A method for manufacturing the electrostatic chuck, wherein the electrostatic chuck is manufactured.
The ceramic substrate having the opening is processed to remove a part of the resistance heating element through the opening to adjust the resistance value of the resistance heating element.
A process is performed to remove a part of the resistance heating element through the opening so as to narrow the line width of the resistance heating element exposed at the opening, and the resistance value of the resistance heating element is determined. adjust,
Manufacturing method of electrostatic chuck. The resistance heating element has a linear portion having a predetermined width in a plan view of the ceramic substrate in the thickness direction, and the width of the opening is larger than the width of the linear portion. be,
The method for manufacturing an electrostatic chuck according to claim 1. The width of the portion to be processed to remove a part of the resistance heating element is set wider than the width of the other portion of the resistance heating element in advance, and the resistance is narrowed so as to narrow the width of the wide portion. The resistance value of the resistance heating element is adjusted by removing a part of the heating element.
The method for manufacturing an electrostatic chuck according to claim 1 or 2 . After adjusting the resistance value, the inside of the opening is sealed with at least one of the ceramics and the resin having the same thermal conductivity as the ceramic substrate or having a higher thermal conductivity than the thermal conductivity of the ceramics substrate. Has a process of arranging materials,
The method for manufacturing an electrostatic chuck according to any one of claims 1 to 3 . A step of producing a first ceramic green sheet and a second ceramic green sheet laminated on the first ceramic green sheet.
A step of forming a resistance heating element pattern made of the material of the resistance heating element on the surface of the first ceramic green sheet, and a step of forming the resistance heating element pattern.
A step of forming a through hole as an opening in the second ceramic green sheet in accordance with the position of the resistance heating element pattern on the first ceramic green sheet.
A step of laminating the second ceramic green sheet on the first ceramic green sheet so that the position of the resistance heating element pattern and the position of the through hole are aligned with each other to form a laminated body.
The step of firing the laminate to form the ceramic substrate having the opening, and
Have,
The method for manufacturing an electrostatic chuck according to any one of claims 1 to 4 .

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