JP2005166821A - Electrostatic chuck for holding wafer and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic chuck for holding wafer which can prevent breakdown of the wafer and generation of particle from the flaw at the rear surface because of fluctuation in attracting force due to fluctuation of volume resistivity in the chuck resulting from temperature change and temperature gradient in accordance with the processing condition of wafer as an object of holding. <P>SOLUTION: The wafer holding electrostatic chuck comprises an aluminum nitride system dielectric layer having a wafer placing surface and a ceramic system base material to be joined to the rear surface of the above dielectric layer via a metallic electrode. In this wafer holding electrostatic chuck, a room temperature volume resistivity of the aluminum nitride system dielectric layer is different as it goes to the circumference from the center thereof. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrostatic chuck for holding a wafer and a method for manufacturing the same. More specifically, according to the present invention, the room temperature volume resistivity of the dielectric layer is controlled in advance according to the processing conditions of the wafer to be held by adsorption, and the adsorption force is not affected by temperature change or temperature gradient during processing. The present invention relates to a wafer holding electrostatic chuck that controls the above and a method for efficiently manufacturing the same.

In a film forming apparatus such as a CVD apparatus or a sputtering apparatus used in a semiconductor manufacturing process or an etching apparatus for performing fine processing, a chuck is used to hold or convey a wafer.
In this chuck, a conventional vacuum chuck method or a mechanical clamp method has been employed. However, with the recent advancement of semiconductor manufacturing processes, an electrostatic chuck (ESC) method has come to be used. Yes. This electrostatic chuck method exhibits superior characteristics compared to the conventional vacuum chuck method and mechanical clamp method in terms of correcting wafer flatness and heating.

As an electrostatic chuck, chucks using various materials such as resin and composites in addition to ceramics are known, but they are used in high temperature and corrosive atmospheres such as film formation, etching and ashing processes. And ceramic electrostatic chucks. An electrostatic chuck consists of a dielectric layer on which a wafer is mounted / held, an electrode formed of a conductive material such as metal, and a substrate having an electrode connection terminal. It is configured. A voltage is applied to the electrode through the electrode connection terminal, and an electrostatic adsorption force by a Coulomb force or a Johnson-Rahbek force is generated by the volume resistivity of the dielectric layer to hold the wafer. A gas groove is often formed on the surface of the dielectric layer as a He gas flow path for making the wafer temperature uniform.
This electrostatic chuck is intended to hold the wafer flat, but a temperature change or a temperature gradient may occur depending on the processing conditions of the wafer. Since the volume resistivity of ceramics is generally temperature-dependent, the volume resistivity in the chuck varies due to the temperature gradient during wafer processing. Particles are generated from scratches on the back surface, leading to an undesirable situation such as a decrease in the yield of semiconductor manufacturing.

In an electrostatic chuck using a material having a single volume resistivity as a dielectric layer, as a method for controlling the attractive force, a method for obtaining a predetermined attractive force by changing the electrode position, that is, changing the thickness of the dielectric layer. Alternatively, there is a method of using a bipolar electrode or the like and controlling by a plurality of power supplies with different applied voltages.
However, the control method that changes the thickness of the dielectric layer inevitably complicates the manufacturing process due to the multilayer lamination of the dielectric layers, and the control method that uses different applied voltages requires an increase in the number of power supplies, which increases the cost. It becomes.

  The present invention has been made under such circumstances, and the volume resistivity in the chuck varies due to temperature changes and temperature gradients depending on the processing conditions of the wafer that is the object to be held. An object of the present invention is to provide an electrostatic chuck for holding a wafer capable of preventing the wafer from being damaged or particles from being generated from scratches on the back surface thereof.

  As a result of intensive studies to develop a wafer holding electrostatic chuck having the above-mentioned preferable performance, the present inventors have found that an aluminum nitride dielectric layer having a wafer mounting surface and a metal electrode on the back surface thereof. In an electrostatic chuck for holding a wafer having a ceramic base material bonded via a substrate, the room temperature volume resistivity of the aluminum nitride dielectric layer is directed from the center to the periphery in accordance with a temperature gradient during wafer processing. It was found that by controlling differently, an electrostatic chuck for holding a wafer that can meet the purpose can be obtained, and that this electrostatic chuck can be efficiently manufactured by performing a specific process. . The present invention has been completed based on such findings.

That is, the present invention
(1) In an electrostatic chuck for holding a wafer having an aluminum nitride dielectric layer having a wafer mounting surface and a ceramic substrate bonded to the back surface of the aluminum nitride dielectric layer through a metal electrode, the aluminum nitride dielectric The electrostatic chuck for holding a wafer, wherein the room temperature volume resistivity of the layer is different from the center toward the periphery,
(2) The electrostatic chuck for holding a wafer according to the above (1), wherein the room temperature volume resistivity of the aluminum nitride-based dielectric layer varies from the center to the periphery in the range of 10 ⁵ to 10 ¹³ Ω · cm according to the operating temperature. ,
(3) The aluminum nitride-based dielectric layer has two regions having different room temperature volume resistivity, the room temperature volume resistivity of the central region is high, and the room temperature volume resistivity of the outer peripheral region is low (1) or (2) The electrostatic chuck for holding a wafer as described,
(4) The aluminum nitride-based dielectric layer has two regions having different room temperature volume resistivity, the room temperature volume resistivity of the central region is low, and the room temperature volume resistivity of the outer peripheral region is high (1) or (2) The electrostatic chuck for holding a wafer as described,

(5) After setting a metal electrode on a ceramic base material, and installing and crimping an aluminum nitride material for forming a dielectric layer with a room temperature volume resistivity varying from the center to the periphery, The pressure-bonded body is pressure-sintered at a temperature of 1550 to 1850 ° C. to produce an integrated sintered body, and then an electrode connection terminal insertion hole is provided in the ceramic-based substrate of the sintered body. A method of manufacturing an electrostatic chuck for holding a wafer, characterized by attaching a system terminal to a metal-based electrode in the sintered body, and (6) forming a dielectric layer having a room temperature volume resistivity varying from the center to the periphery The method for producing an electrostatic chuck for holding a wafer according to (5), wherein the aluminum nitride material for use is a combined system of an aluminum nitride-based preform and an aluminum nitride-based powder having different room temperature volume resistivity after sintering ,
Is to provide.

  According to the present invention, the room temperature volume resistivity of the dielectric layer is controlled in advance according to the processing conditions of the wafer to be held by suction, so that it is not affected by temperature changes or temperature gradients during wafer processing. The power can be controlled. As a result, it is possible to suppress wafer breakage due to variations in adsorption force and generation of particles from scratches on the back surface without multilayering dielectric layers or using a plurality of power sources.

The electrostatic chuck for holding a wafer according to the present invention includes an aluminum nitride dielectric layer having a wafer mounting surface and a ceramic substrate bonded to the back surface of the dielectric chuck via a metal electrode.
Examples of the ceramic constituting the ceramic base material include materials having corrosion resistance such as alumina, aluminum nitride, silicon carbide, silicon nitride, magnesia, yttria, YAG (a composite oxide of Y and Al having a garnet structure), and the like. Among these composites, aluminum nitride is preferred because of its thermal expansion coefficient close to that of Si and high thermal conductivity characteristics. The ceramic base material used in the present invention forms, for example, a suitable sintering aid, specifically Y ₂ O ₃ , lanthanoid oxide, Al ₂ O ₃ or the like on AlN powder, or these oxides by firing. A molding material formed by adding a substance to be added and further blended with an organic binder is pressure-molded into a predetermined shape, and then calcined and degreased by firing at a temperature of 400 ° C. or higher, preferably about 600 ° C. in the atmosphere as desired. After the treatment, it can be produced by sintering at a temperature of 1800 ° C. or higher under an inert gas atmosphere such as nitrogen gas or under reduced pressure.

The ceramic base material thus obtained is not particularly limited with respect to its volume resistivity. From a high resistance product having a room temperature volume resistivity of 10 ¹⁴ Ω · cm or more, a volume substantially equal to that of a dielectric layer described later is used. It can be selected appropriately according to the type and usage of the electrostatic chuck, such as one having resistivity. The volume resistivity of the ceramic base material can be adjusted, for example, depending on the kind and amount of the sintering aid added to the AlN powder. Although there is no restriction | limiting in particular about the thickness of this ceramic type | system | group base material, Usually, 2-50 mm, Preferably it selects in the range of 5-25 mm.

The metal electrode in the electrostatic chuck of the present invention is made of a conductive metal material such as a metal such as W, Mo, Ta, Pt, Ni, Cu, Ag, Au, an alloy of these metals, or a mixture thereof. In the case of using the aluminum nitride-based substrate as the ceramic-based substrate, those made of W or Mo are particularly preferable because of their close thermal expansion coefficients.
As the form of the metal electrode, for example, a paste formed of an electrode material is formed by applying by screen printing, formed by a method such as sputtering, vacuum deposition, or thermal spraying, and a thin plate is formed into an electrode shape. And those obtained by processing a mesh into an electrode shape.

On the other hand, the aluminum nitride-based dielectric layer in the electrostatic chuck of the present invention is composed of an aluminum nitride-based material containing AlN as a main component, and the material is a lanthanoid oxide such as Y ₂ O ₃ or Nd ₂ O _3. Or the like.
In the present invention, the aluminum nitride-based dielectric layer needs to be controlled such that the room temperature volume resistivity differs from the central portion toward the peripheral edge. Specifically, the room temperature volume resistivity of the dielectric layer is controlled in accordance with the processing conditions of the wafer attracted and held by the electrostatic chuck, for example, the temperature gradient during processing. In this way, by controlling the room temperature volume resistivity of the dielectric layer, the adsorption force can be controlled without being affected by temperature changes or temperature gradients during wafer processing.

The volume resistivity of an aluminum nitride dielectric layer is generally temperature-dependent (volume resistivity decreases as the temperature increases), so the volume resistivity in the chuck varies due to the temperature gradient during wafer processing, and the resulting adsorption There is a risk that the yield of semiconductor manufacturing may be reduced due to troubles such as damage to the wafer or generation of particles from scratches on the back surface due to the variation in force. The above trouble can be avoided by controlling the room temperature volume resistivity.
Control of room temperature volume resistivity in the dielectric layer is usually performed in accordance with a temperature gradient during wafer processing as described above. As a form of control of room temperature volume resistivity, for example, (1) center of dielectric layer is used. A form in which the room temperature volume resistivity decreases continuously or stepwise from the part to the periphery, or (2) a form in which the room temperature volume resistivity increases continuously or stepwise can be exemplified. Since the volume resistivity of the dielectric layer decreases as the temperature of the dielectric layer increases, the form (1) is applied when the temperature gradient during wafer processing decreases from the center toward the periphery. On the other hand, the form (2) can be applied to the case opposite to the above. Among these forms, the form in which the room temperature volume resistivity decreases stepwise or increases stepwise is preferable from the viewpoint of manufacturing the electrostatic chuck. In this case, the number of regions having different room temperature volume resistivity is not particularly limited, but 2 or 3 is preferable from the viewpoint of production, and 2 is particularly preferable. That is, the dielectric layer has two regions having different room temperature volume resistivity, and has a form in which the room temperature volume resistivity is high in the central region and the room temperature volume resistivity in the outer peripheral region is low, or the room temperature volume resistivity in the central region. A material having a low rate and a high room temperature volume resistivity in the outer peripheral region is preferable.

In the dielectric layer, the volume resistivity is room temperature volume resistivity from the viewpoint of the performance of the electrostatic chuck, and is usually 10 ⁵ to 10 ¹³ Ω · cm, preferably 10 ⁹ to 10 ¹¹ Ω · cm. It is desirable that the difference is from the center to the periphery.
The room temperature volume resistivity of the aluminum nitride-based material mainly composed of AlN constituting the aluminum nitride-based dielectric layer is the kind and amount of sintering aids such as Y ₂ O ₃ and lanthanoid oxide contained therein. It is preferable to control by such as. Among the sintering aids, lanthanoid oxide functions effectively as a resistance control aid, so it is advantageous to control the room temperature volume resistivity by changing the content of lanthanide oxide.

Although there is no restriction | limiting in particular about the thickness of the said dielectric layer, Usually, 0.5-5 mm, Preferably it is selected in the range of 1-3 mm.
As described above, the electrostatic chuck according to the present invention is a chuck having an aluminum nitride dielectric layer having a wafer mounting surface and a ceramic substrate bonded to the back surface of the dielectric substrate via a metal electrode. Furthermore, a chuck is also included in which an electrode connection terminal insertion hole is provided from the back side of the ceramic base material, and a metal terminal is attached to an internal metal electrode.
The electrostatic chuck for holding a wafer of the present invention having such a configuration and properties is used for electrostatically attracting and holding a wafer in a semiconductor manufacturing apparatus. And by controlling the room temperature volume resistivity of the dielectric layer in advance according to the processing conditions of the wafer to be held by suction, the suction force is controlled without being affected by temperature changes or temperature gradients during wafer processing. As a result, it is possible to effectively control the breakage of the wafer caused by the variation in adsorption force and the generation of particles from the back surface scratches.

  Next, the method for producing the electrostatic chuck for holding a wafer according to the present invention is not particularly limited as long as the electrostatic chuck having the above-described configuration and properties can be obtained. Various methods such as ( 1) Method of adhering an aluminum nitride sintered compact to be a dielectric layer to a ceramic base material via a metal electrode, (2) Aluminum nitride sintered compact to be a dielectric layer, a metal electrode and a ceramic preliminary A method of laminating a molded base material in this order and pressurizing and sintering by hot pressing, (3) an aluminum nitride powder and / or a preform, a metal electrode, and a ceramic base material to be a dielectric layer, A method of laminating in this order and pressure sintering by hot pressing, (4) an aluminum nitride powder and / or a preform, a metal electrode and a ceramic preform to be a dielectric layer, Is a sequentially stacked, it may be used a method of pressure sintering by hot pressing, and the like. Among these, the method (3) is preferable, and a desired electrostatic chuck can be efficiently produced by using the method of the present invention shown below.

In the method of the present invention, first, a metal electrode is placed on a ceramic substrate processed into a predetermined shape, and aluminum nitride for forming a dielectric layer having a room temperature volume resistivity varying from the center to the periphery on the metal electrode. A system material is placed and crimped to produce a crimped body.
Here, there is no particular limitation on the method of installing the metal-based electrode on the ceramic-based substrate, and a method in which the electrode material paste is applied by screen printing as described above, sputtering, vacuum deposition There are a method of forming by a method such as spraying, a method of placing a thin plate in an electrode shape, a method of placing a mesh processed into an electrode shape, etc., among these, processing into a predetermined shape A system in which the metal mesh is placed is preferable.
The aluminum nitride-based material for forming a dielectric layer that has a room temperature volume resistivity that varies from the central part toward the periphery, which is installed on the metal electrode thus installed, has a room temperature volume resistivity after sintering. A combined system of different aluminum nitride-based preforms and aluminum nitride-based powder is preferred.

Here, as the aluminum nitride-based powder, mixed powder in which AlN powder is mixed with a sintering aid, such as Y ₂ O ₃ or lanthanoid oxide, or a substance that forms these oxides by firing, is mixed with an organic material such as alcohol. Add the medium, disperse and mix with a ball mill, etc., remove the organic medium and sieve, or add the binder component to the above mixed powder and granulate with a spray dryer, etc. Is preferably a fluid powder such as one obtained by decomposing and removing the binder by heat treatment at a temperature of about 600 ° C.

As the aluminum nitride-based preform, a product obtained by molding the aluminum nitride-based powder obtained as described above into a predetermined shape at a pressure of about 5 to 10 N / mm ² can be used. If the molding pressure is in the above range, the resulting preform has sufficient strength, good handleability, and is less prone to cracks.
As a method of using the aluminum nitride-based preform and the aluminum nitride-based powder in combination on the metal-based electrode, for example, a disk-shaped aluminum nitride-based preform is placed at the center and the outer periphery thereof is placed. A method of filling the part with aluminum nitride-based powder or a method of placing a ring-shaped aluminum nitride-based preform on the outer peripheral part and filling the inner space with the aluminum nitride-based powder can be used. Further, a method of filling the aluminum nitride powder in both the central portion and the outer peripheral portion by using a filling jig or the like can also be used.
In this way, after installing an aluminum nitride material for forming a dielectric layer having a different room temperature volume resistivity from the center to the periphery on the metal-based electrode, pressure bonding is performed at a pressure of about 10 to 50 N / mm ^2. Thus, a pressure-bonding body having an electrode is produced. If this pressure is 10 N / mm ² or more, the members constituting the pressure-bonded body are sufficiently adhered, and if it is 50 N / mm ² or less, the ceramic base material and the aluminum nitride-based preform are not easily damaged. .

Next, the pressure-bonded body thus obtained is subjected to an inert gas atmosphere such as nitrogen gas under conditions of a temperature of 1550 to 1850 ° C., a pressure of about 5 to ²⁰ N / mm ² , and a holding time of about 3 to 10 hours. By sintering under pressure under reduced pressure, sintering of the aluminum nitride material for forming the dielectric layer, embedding of the metal-based electrode, and bonding of the ceramic substrate to the formed dielectric layer were performed at the same time. A sintered body is produced. If the sintering temperature and holding time are within the above ranges, densification proceeds sufficiently and the room temperature volume resistivity can be controlled as desired. Further, if the sintering pressure is within the above range, the densification proceeds sufficiently, and deformation and breakage of the ceramic base material and the dielectric layer can be prevented.
The sintered body obtained in this way is machined to process the outer periphery and thickness to predetermined dimensions, and further provided with electrode connection terminal insertion holes from the back side of the ceramic base material, An electrostatic chuck is obtained by connecting to a metal electrode by brazing or the like. This electrostatic chuck can be appropriately provided with a gas supply hole, a lift pin hole, a groove serving as a gas flow path, and the like according to the intended use and conditions. In order to improve the corrosion resistance, the surface may be coated with a yttrium compound or the like.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
Example 1
An electrostatic chuck was manufactured according to the manufacturing process shown in FIG. Reference numeral 8 denotes a die.
A high-resistance aluminum nitride-based sintered body having a room temperature volume resistivity of 10 ¹⁴ Ω · cm or more is machined into a disk shape having a diameter of 340 mm and a thickness of 25 mm to form a ceramic-based substrate 1, which is formed in a mold press. It installed in the lower punch 6a (a). Next, a Mo mesh (# 50) having a diameter of 315 mm and a wire diameter of 0.12 mm was placed on the substrate 1 as the electrode 2 (b), and then molded in advance with a press pressure of 9.8 N / mm ^2. The aluminum nitride-based preform 3a for the central portion of the dielectric layer having a diameter of 160 mm and a thickness of 10 mm (including 1% by mass of Y ₂ O ₃ and 0.1% by mass of Nd ₂ O ₃ as auxiliary agents with respect to AlN). (C), (d). Subsequently, an aluminum nitride-based powder for a dielectric layer outer peripheral portion having a volume resistivity different from that for the central portion (1% by mass of Y ₂ O ₃ and Nd ₂ O ₃ 0 as an auxiliary agent with respect to AlN) is provided on the outer peripheral portion. 3b (containing 0.05 mass%) (e), and after setting the upper punch 6b, it was pressurized at 29 N / mm ² to obtain a molded body 7 in which the electrode was contained (f).
Next, the compact 7 containing this electrode was subjected to pressure firing in a hot press furnace under a nitrogen gas atmosphere under conditions of a sintering temperature of 1800 ° C., a pressure of 9.8 N / mm ² , and a holding time of 7 hours. Yui was done. The obtained sintered joined body is machined to be processed into a diameter of 320 mm and a thickness of 25 mm (including the dielectric layer 3 having a thickness of 1 mm). 4 and the metal-based terminal 5 was connected to the electrode by brazing to produce an electrostatic chuck 10 (g).
The volume resistivity of the dielectric layer of the electrostatic chuck 10 at room temperature was 2.2 × 10 ¹⁰ Ω · cm at the center and 8 × 10 ¹⁰ Ω · cm at the outer periphery, and a DC voltage of 500 V was applied. The suction force at that time was center portion> outer peripheral portion.
In this electrostatic chuck, since the room temperature volume resistivity of the dielectric layer is controlled as described above, when the temperature gradient when processing the attracted and held wafer is low in the central portion and high in the outer peripheral portion, By applying, variation in adsorption force can be suppressed.

Example 2
In Example 1, as the aluminum nitride-based preform 3a for the central portion of the dielectric layer, a material containing 1% by mass of Y ₂ O ₃ and 0.05% by mass of Nd ₂ O ₃ as an auxiliary agent with respect to AlN was used. In addition, Example 1 was used except that the aluminum nitride powder 3b for the outer peripheral portion of the dielectric layer was a material containing 1% by mass of Y ₂ O ₃ and 0.1% by mass of Nd ₂ O ₃ as auxiliary agents with respect to AlN. The electrostatic chuck 10 was manufactured by performing the same operation as described above.
The volume resistivity of the dielectric layer of the electrostatic chuck 10 at room temperature is 7.8 × 10 ¹⁰ Ω · cm at the center and 2.5 × 10 ¹⁰ Ω · cm at the outer periphery, and a DC voltage of 500 V is applied. The adsorption force at the time of application was center portion <outer peripheral portion.
In this electrostatic chuck, since the room temperature volume resistivity of the dielectric layer is controlled as described above, when the temperature gradient when processing the attracted and held wafer is high in the central portion and low in the outer peripheral portion, By applying, variation in adsorption force can be suppressed.

Comparative Example 1
In order to produce an electrostatic chuck having the same adsorption force distribution as in Example 1, the following operation was performed.
A donut-shaped Mo mesh electrode A having an outer diameter of 315 mm, an inner diameter of 165 mm, and a wire diameter of 0.12 mm, and a disc-shaped Mo mesh electrode B having a diameter of 160 mm and a wire diameter of 0.12 mm were prepared.
Next, a disk-shaped substrate having a diameter of 340 mm and a thickness of 25 mm made of a high-resistance aluminum nitride-based sintered body having a room temperature volume resistivity of 10 ¹⁴ Ω · cm or more similar to the substrate used in Example 1 is made of gold. The Mo mesh electrode A was placed on the lower punch in the mold press, and the Mo mesh electrode B was placed on the inner space. Next, an aluminum nitride-based powder for dielectric layer (containing 1% by weight of Y ₂ O ₃ and 0.05% by weight of Nd ₂ O ₃ as an auxiliary agent with respect to AlN) is filled thereon, and an upper punch is installed. Then, it pressed with 29 N / mm < ² > and the molded object which contained the electrode was obtained.
Next, the compact in which this electrode is contained is sintered under pressure in a nitrogen gas atmosphere in a hot press furnace under the conditions of a sintering temperature of 1800 ° C., a pressure of 9.8 N / mm ² , and a holding time of 7 hours. Went. The obtained sintered joint is machined to have a diameter of 320 mm and a thickness of 25 mm (including a dielectric layer thickness of 1 mm), and then the electrode connection with a diameter of 12 mm for each electrode from the back side of the substrate. An electrostatic chuck was prepared by providing two terminal insertion holes and connecting the metal terminals to the electrodes by brazing.
The volume resistivity of the dielectric layer of this electrostatic chuck at room temperature is 8.1 × 10 ¹⁰ Ω · cm, a DC voltage of 500 V is applied to the Mo mesh electrode B at the center, and the Mo mesh electrode A at the outer periphery is applied. When a DC voltage of 700 V was applied from another power source, the same adsorption force distribution as in Example 1 was obtained.

  The electrostatic chuck for holding a wafer of the present invention can control the attracting force without being affected by temperature change or temperature gradient during wafer processing. Therefore, it is possible to suppress the wafer damage caused by the variation in the attractive force and the generation of particles from the scratches on the back surface without stacking multiple dielectric layers or using a plurality of power sources.

In an Example, it is a manufacturing process figure for producing an electrostatic chuck.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ceramic base material 2 Mo mesh electrode 3a Aluminum nitride type preform for dielectric layer center part 3b Aluminum nitride type powder for dielectric layer outer peripheral part 3 Dielectric layer 4 Electrode connection terminal insertion hole 5 Metal system terminal 6a Bottom punch 6b Upper punch 7 Molded body 8 Die 10 Electrostatic chuck

Claims (6)

  In an electrostatic chuck for holding a wafer having an aluminum nitride dielectric layer having a wafer mounting surface and a ceramic substrate bonded to the back surface of the aluminum nitride dielectric layer through a metal electrode, the room temperature of the aluminum nitride dielectric layer is An electrostatic chuck for holding a wafer, wherein the volume resistivity is different from a central portion toward a peripheral edge. 2. The electrostatic chuck for holding a wafer according to claim 1, wherein the room temperature volume resistivity of the aluminum nitride-based dielectric layer varies from the center to the periphery in the range of 10 < ⁵ > to 10 < ¹³ > [Omega] .cm according to the operating temperature.   3. The wafer holding static electricity according to claim 1, wherein the aluminum nitride-based dielectric layer has two regions having different room temperature volume resistivity, the room region volume resistivity is high in the central region, and the room temperature volume resistivity in the outer peripheral region is low. Electric chuck.   3. The wafer holding static electricity according to claim 1, wherein the aluminum nitride-based dielectric layer has two regions having different room temperature volume resistivity, the room temperature volume resistivity of the central region is low, and the room temperature volume resistivity of the outer peripheral region is high. Electric chuck.   A metal electrode is placed on a ceramic base material, and an aluminum nitride material for forming a dielectric layer having a different room temperature volume resistivity from the center to the periphery is placed on the ceramic base, and then crimped. Is sintered at a temperature of 1550 to 1850 ° C. to produce an integrated sintered body, and then an electrode connection terminal insertion hole is provided in the ceramic base material of the sintered body, and the metal terminal is A method for producing an electrostatic chuck for holding a wafer, wherein the method is attached to a metal-based electrode present in the sintered body. An aluminum nitride-based material for forming a dielectric layer having a different room temperature volume resistivity from the center to the periphery is a combination of an aluminum nitride-based preform and an aluminum nitride-based powder having different room temperature volume resistivity after sintering. A method for manufacturing an electrostatic chuck for holding a wafer according to claim 5.

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