JPH11100271A - Ceramic resistor and electrostatic chuck using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic resistor which has a 10<8> to 10<12> Ω.cm volume resistivity at 0 to 50 deg.C and is capable of obtaining a high attracting force due to the Johnson-Rabbeck effect at <=200 deg.C and also, to provide an electrostatic chuck using the ceramic resistor. SOLUTION: This resistor 2 consists essentially of aluminum nitride and concurrently contains 2 to 20 mol.% cerium expressed in terms of cerium oxide (CeO2 ) and CeAlO3 and also, has a 10<8> to 10<12> Ω.cm volume resistivity at 0 to 50 deg.C and is used as a component of an electrostatic chuck 1 for attracting and holding an object to be fixed by electrostatic force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is excellent in abrasion resistance, corrosion resistance, and plasma resistance, and holds an object to be fixed such as a semiconductor wafer or a glass substrate mainly in a manufacturing process of a semiconductor device or a liquid crystal substrate. In particular, the present invention relates to a ceramic resistor having a high electrostatic force used for an electrostatic chuck or the like that holds an object to be fixed by electrostatic force and an electrostatic chuck using the same.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor manufacturing process, an etching process for performing fine processing on a semiconductor wafer (hereinafter, referred to as a wafer), a film forming process for forming a thin film, or an exposure process for performing a photoresist. In a processing step or the like, an electrostatic chuck is used to hold a wafer.

[0003] As this kind of electrostatic chuck, an electrostatic chuck in which a dielectric layer made of alumina, sapphire, or the like is formed on an electrode plate for electrostatic attraction (Japanese Patent Application Laid-Open No. 60-261377), or an insulating substrate is used. An electrode for electrostatic attraction formed thereon and a dielectric layer formed thereon (Japanese Patent Application Laid-Open No. 4-34953), and further an electrode for electrostatic attraction embedded within a substrate made of a dielectric material (Japanese Patent Application Laid-Open No. Sho 62-94953) has been proposed in which the upper surface of a dielectric layer is used as an adsorption surface.

In the electrostatic chuck having the above structure, a wafer is placed on a suction surface, and a voltage is applied between the electrostatic chucking electrode and the wafer, thereby causing Coulomb force or Johnson-Rahbek force due to dielectric polarization. This is to exert electrostatic force to attract and hold the wafer. Further, there has been proposed an electrostatic chuck having a bipolar structure in which an electrostatic chucking electrode is divided into a plurality of parts and a voltage is applied between the electrodes to suck and hold a wafer placed on a suction surface.

On the other hand, in recent years, as the degree of integration of an integrated circuit in a semiconductor device has been improved and severe conditions have been applied to the semiconductor manufacturing process, the dielectric layer constituting the suction surface has been required to be resistant to the desorption of the wafer. In addition to abrasion resistance and corrosion resistance to corrosive gases used in various processing steps, a material having excellent plasma resistance and high thermal conductivity has been desired. As such a material, high-purity aluminum nitride has been demanded. and quality sintered body, mainly as a sintering aid Y ₂ O ₃ and Er ₂
It has been proposed to use an aluminum nitride sintered body containing O ₃ .

[0006]

As described above, there are two types of electrostatic force for attracting a wafer, the Coulomb force and the Johnson-Rahbek force. The Coulomb force depends on the dielectric constant of the material constituting the dielectric layer. The Johnson-Rahbek force depends on the volume resistivity of the material constituting the dielectric layer. Specifically, the volume resistivity of the dielectric layer is 10 ¹⁵ Ω
The adsorption force when larger than cm is governed by Coulomb force, and Johnson-Rahbek force appears as the volume resistivity of the dielectric layer decreases, and the volume resistivity of the dielectric layer becomes 10 ¹² Ω · cm. It is known that when the value is less than the above, the adsorption force is governed by the Johnson-Rahbek force, which provides a larger adsorption force than the Coulomb force.

The high-purity aluminum nitride sintered body and the aluminum nitride sintered body mainly containing Y ₂ O ₃ or Er ₂ O ₃ as a sintering aid are high at a high temperature of 250 ° C. or higher. Although a suction force can be obtained, there is a problem that a sufficient suction force cannot be obtained in a film forming step, an exposure processing step, an etching step, or the like performed at a temperature of 200 ° C. or lower.

That is, the volume resistivity of the aluminum nitride sintered body decreases as the temperature rises,
Although the temperature is about 10 ¹¹ Ω · cm at a temperature of 00 ° C. or more, a high adsorption force by the Johnson-Rahbek force can be obtained, but at a temperature of 200 ° C. or less, 10 ¹⁶ Ω · cm.
As described above, since the insulating property is high, only the attraction force due to the Coulomb force can be obtained, and since the dielectric constant is not so high, the attraction force due to the Coulomb force is small, and a sufficient attraction force cannot be obtained.

Therefore, when a wafer having a distortion is sucked, the entire surface of the wafer cannot be brought into contact with the suction surface due to a small suction force of the electrostatic chuck, and the wafer is flattened on the film formation surface. Has a problem in that the heat equalization is impaired, a thin film having a uniform thickness cannot be formed on the wafer in the film forming process, and high-precision processing cannot be performed in the exposure process and the etching process. Yes, and could only be used at high temperatures.

[0010]

In view of the above, the present inventors have solved the above problem with respect to aluminum nitride sintered bodies.
As a result of repeated investigations on compositions that enhance the adsorptive power in the low-temperature region of 00 ° C. or lower, cerium (C
e) in a specific range, and CeAl
By precipitating the O ₃ phase, the volume resistivity at a temperature of 200 ° C. or less can be reduced to the extent that the Johnson-Rahbek force can be developed, and the temperature dependence (resistance temperature coefficient) of the resistance is reduced. It has been found that an electrostatic chuck that can be used in a wide temperature range having a high suction force even at a temperature of 200 ° C. or less can be obtained.

That is, the ceramic sintered body of the present invention contains aluminum nitride as a main component and cerium as an oxide (CeO).
₂ ) In the range of 2 to 20 mol% in terms of conversion, and CeAl
It contains O ₃ and has a volume resistivity of 1 at 0 to 50 ° C.
0 ⁸ to 10 ¹² Ω · cm.

Further, the electrostatic chuck according to the present invention holds an object by suction by electrostatic force, wherein the suction surface for holding the object is aluminum nitride as a main component and cerium as an oxide. (CeO ₂ ) in a range of 2 to 20 mol%, and CeAlO ₃ ,
Volume specific resistance at 0 ° C. of 10 ⁸ to 10 ¹² Ω · cm
It is characterized by being.

[0013]

Cerium (Ce) is a sintering aid component added to enhance the sinterability of aluminum nitride, which is a difficult-to-sinter material. Present as CeAlO ₃ phase.

[0014]

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When cerium (Ce) forms an oxide, its valence is usually tetravalent, but when it forms a CeAlO ₃ phase, it becomes trivalent and the valence changes, resulting in vacancies in the crystal. Shows electrical conductivity to generate.

Then, CeAlO ₃ exhibiting this conductivity is present between aluminum nitride particles as an insulating material, that is, between grain boundaries.
When the phases are continuously present, conduction can be achieved through the grain boundaries, and the resistance value of the aluminum nitride sintered body can be reduced.

In addition, since the CeAlO ₃ phase intervenes at the grain boundary, the rate of change of the resistance value with respect to the temperature change can be reduced (the temperature coefficient of resistance is small). An electric chuck can be provided.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION A ceramic sintered body of the present invention contains aluminum nitride as a main component and cerium as an oxide (Ce).
O ₂ ) in the range of 2 to 20 mol% in terms of CeA
It is important that it contains 10 ₃ and has a volume resistivity at 0 to 50 ° C. of 10 ⁸ to 10 ¹² Ω · cm.

In order to obtain the adsorption force by the Johnson-Rahbek force in the temperature range of -50 ° C to 200 ° C, the volume resistivity in the temperature range of 0 ° C to 50 ° C should be 10 ⁸ to 10.
It is necessary to be ¹² Ω · cm, and by setting the cerium content to 2 to 20 mol%, preferably 5 to 15 mol%, the volume resistivity in the temperature range from 0 ° C. to 50 ° C. ⁸ to 10 ¹² Ω · cm, especially 10 ⁹ to 10 ¹¹ Ω
Cm, and the adsorption force by the Johnson-Rahbek force can be obtained, so that the adsorption force of such a sintered body is dramatically improved.

That is, if the content of cerium (Ce) is less than 2 mol% in terms of oxide (CeO ₂ ), the amount of CeAlO ₃ phase generated at the grain boundary is small, so that the volume of the sintered body is reduced. This is because the effect of lowering the specific resistance value is small and the effect of reducing the temperature coefficient of resistance is also small, making it difficult to obtain a desired resistance value. Conversely, if it exceeds 20 mol%, the strength and thermal conductivity of the sintered body This is because such factors are reduced.

The average crystal grain size of aluminum nitride is preferably 0.5 to 50 μm, particularly preferably 3 to 30 μm. This is because if the average crystal grain size of aluminum nitride is larger than 50 μm, the strength and hardness of the sintered body are greatly reduced. This is because the life of the electrostatic chuck is shortened and particles adhere to the fixed object because the plasma and corrosive gas in the etching process and the like easily cause corrosion and wear, and conversely, the average crystal particles of aluminum nitride This is because making the diameter smaller than 0.5 μm is difficult in manufacturing.

The strength of the ceramic resistor of the present invention is desirably 100 MPa or more because the ceramic resistor may be used at a thickness of 3 mm or less.

In the ceramic resistor of the present invention, cerium (C) is used as a sintering aid in order to promote densification.
e) Besides compounds, yttrium (Y), erbium (E
r), a rare earth oxide such as ytterbium (Yb) may be contained in an amount of 2 mol% or less. This further promotes densification of the ceramic, thereby improving corrosion resistance and abrasion resistance, and when used as an electrostatic chuck, can reduce the generation of particles due to shedding and the like generated from the ceramic surface. Reliability is improved.

The method for producing a ceramic sintered body of the present invention will be described below. First, aluminum nitride powder as a starting material (purity of 99% or more, average particle size of 0.4 μm
Cerium oxide (CeO ₂ ) powder (purity: 99% or more, average particle size: 0.5 μm to 18 μm) with respect to 5.5 μm) in an amount of 2 to 20 mol% in terms of cerium oxide (CeO ₂ ).
Add and mix within the range. Note that oxygen is present as an impurity in the raw material, and this oxygen can promote the above-mentioned reaction of Chemical Formula 1. Further, by adding aluminum oxide (Al ₂ O ₃ ) to the powder, the following reaction of Chemical Formula 2 can be promoted.

[0025]

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It should be noted that aluminum oxide (Al
_{When 2} O ₃ ) precipitates, it becomes difficult to control the resistance and stable adsorption characteristics cannot be obtained.
l ₂ O ₃ ) depends on the cerium oxide (CeO ₂ )
Is desirably in a range of 50% or less in terms of molar amount with respect to the amount of addition.

Further, in order to increase the generation rate of the CeAlO ₃ phase, aluminum oxide (Al ₂ O ₃ ) and cerium oxide (CeO ₂ ) are reacted in advance to produce CeAlO ₃ powder. May be uniformly mixed with aluminum nitride powder at a predetermined ratio.

In the present invention, cerium (C
Although e) has the effect of improving sinterability, sufficient sinterability may not be obtained when the content is in a small range. In such a case, rare earth oxides such as yttrium (Y), erbium (Er) and ytterbium (Yb) which have been conventionally used as a sintering additive may be added in a range of 2 mol% or less.

The above-mentioned mixed powder is formed into an arbitrary shape by a known molding means, for example, a die pressing, a cold isostatic pressing, a tape forming method such as a doctor blade method, a rolling method, an extrusion molding and the like.

Thereafter, the molded body is degreased in a vacuum or in nitrogen, and then heated at 1650 ° C. in a non-oxidizing atmosphere such as nitrogen.
２2100 ° C., particularly 1750 ° C. to 1900 ° C.

FIGS. 1 (a) and 1 (b) are a perspective view and a sectional view taken along the line XX of the electrostatic chuck 1 according to the present invention. A dielectric layer 3 is provided on the surface of the ceramic base 2 so as to cover the electrostatic attraction electrode 4, and the upper surface of the dielectric layer 3 serves as an attraction surface 5 for adsorbing the object 10. Has formed. Further, a power supply terminal 6 electrically connected to the electrostatic attraction electrode 4 is embedded on the surface opposite to the attraction surface 5.

Although the resistance value of the dielectric layer 3 constituting the suction surface 5 is closely related to the suction force, according to the electrostatic chuck of the present invention, the resistance value of the aluminum nitride ceramics forming the dielectric layer 3 is zero. The volume resistivity at ~ 50 ° C is 10 ⁸ -10
^Since it can be appropriately adjusted to be in the range of ¹² Ω · cm, the electrostatic chucking electrode 4 of the electrostatic chuck 1 and the suction surface 5
When a voltage is applied between the fixed object 10 and the fixed object 10, a slight leakage current flows between the fixed object 10 and the electrostatic attraction electrode 4. The object 10 can be firmly adsorbed and held on the adsorption surface 5.

In order to enhance the corrosion resistance and the wear resistance, the relative density of the dielectric layer 3 is desirably 95% or more, especially 98% or more, and the thermal conductivity is 15 w / m.
It is desirable that it be K or more, especially 30 w / mK or more.

The ceramic substrate 2 may be formed of an insulating ceramic such as alumina, silicon nitride, aluminum nitride or the like. In particular, the ceramic substrate 2 is formed of aluminum nitride ceramic to form the aluminum nitride forming the dielectric layer 3. Since simultaneous firing with ceramics is possible and a difference in thermal expansion coefficient between the two can be eliminated, a highly reliable electrostatic chuck can be obtained without warping or distortion during firing.

The electrode 4 for electrostatic attraction and the power supply terminal 6 have a coefficient of thermal expansion that is higher than that of the aluminum nitride sintered body constituting the ceramic substrate 2 in order to enhance the adhesion to the ceramic substrate 2 during firing and heating. Approximated tungsten,
It is formed of a heat-resistant metal such as molybdenum and platinum. Further, when the power supply terminal 6 is exposed to a corrosive gas, the power supply terminal 6 is preferably formed of an iron-cobalt-chromium alloy.

Further, since the electrostatic attraction electrode 4 is completely embedded in the ceramic substrate 2 having excellent heat resistance, it can be used at a relatively high temperature of around 200 ° C. The electric chuck 1 has excellent plasma resistance,
Since it is made of an aluminum nitride sintered body having corrosion resistance, even if it is exposed to a plasma or a corrosive gas in a film forming step, an etching step, or the like, it is less corroded and can be used for a long time. In addition, the power supply to the electrostatic attraction electrode 4 is O
If the FF is used, the adsorption force can be immediately removed, so that the FF has excellent desorption response.

Although the electrostatic chuck 1 shown in FIG. 1 shows an example in which only the electrostatic attraction electrode 4 is provided inside the ceramic base 2, for example, a heater electrode other than the electrostatic attraction electrode 4 is provided. May be embedded. In this case, since the electrostatic chuck 1 can directly generate heat by the heater electrode,
Heat loss can be greatly reduced as compared with the indirect heating method.

When the ceramic substrate 2 is made of aluminum nitride ceramics, the object to be fixed 10 held on the adsorption surface 5 can be heated uniformly without unevenness because of its good thermal conductivity. In addition, the electrode for electrostatic attraction 4
If the electrode for plasma generation is buried in the ceramic base 2 in addition to the above, the structure of the device can be simplified. Also,
The electrostatic chuck 1 of the present invention is mainly used in a temperature range of 200 ° C. or lower, but can be used in a temperature range higher than 200 ° C.

Incidentally, in order to manufacture such an electrostatic chuck 1, as a raw material for forming the ceramic base 2,
For example, using a powder of aluminum nitride (AlN) having a purity of 99% or more and an average particle diameter of 3 μm or less, and using a mixed powder having the above-described composition as a raw material for forming the dielectric layer 3, a well-known molding into a predetermined shape. Method, for example, mold press,
It is formed into an arbitrary shape by a cold isostatic pressing, a tape forming method such as a doctor blade method or a rolling method, an extrusion method, or the like.

For example, when the tape forming method is used, a plurality of green sheets forming the ceramic substrate 2 are formed, and a conductive paste is printed on one of the green sheets to form an electrode pattern forming the electrostatic attraction electrode 4. After the formation, each green sheet is laminated. On the other hand, a green sheet for forming the dielectric layer 3 is formed and laminated on the laminate, and the laminate is subjected to cutting to obtain a desired shape.

When a mold press is used, the above-mentioned powder is filled in a mold, and a plate-like or powder-like electrostatic attraction electrode 4 is embedded in the powder and press-molded to form a static press. It is also possible to manufacture a ceramic molded body in which the electrode for electroadsorption 4 is embedded.

After the obtained molded body is degreased in a vacuum or nitrogen, it is subjected to 1650 to 2100 in a non-oxidizing atmosphere.
C., especially at 1750-1900.degree. C. for one to several hours.
As a firing method, a normal pressure firing, a hot press method, a gas pressure firing method, or the like is used. Further, in order to increase the density of the sintered body, the sintered body may be subjected to HIP processing.

Then, the surface of the dielectric layer 3 is polished to form an attraction surface 5, and a hole communicating with the electrostatic attraction electrode 4 is formed at a surface opposite to the attraction surface 5. The power supply terminal 6 is joined by a method such as brazing to obtain the electrostatic chuck 1 shown in FIG.

Next, FIG. 2 shows an electrostatic chuck 1 according to the present invention.
1 is a diagram showing another embodiment, (a) is a perspective view,
(B) is a sectional view taken along line YY of (a). The electrostatic chuck 11 has a disk-shaped dielectric plate 12 made of an aluminum nitride sintered body, an electrostatic attraction electrode 14 laid on the lower surface of the dielectric plate 12, and covers the electrostatic attraction electrode 14. The dielectric plate 12 and the base 1
5 is a bonding agent 1 such as glass, brazing material, or an adhesive.
6, an electrostatic attraction electrode 14 is built in between the dielectric plate 12 and the base body 15, and the upper surface of the dielectric plate 12 serves as an attraction surface 13. A power supply terminal 17 that is electrically connected to the electrostatic attraction electrode 14 is embedded on the back surface of the base substrate 15.

The base substrate 15 is made of sapphire, various ceramics such as alumina, silicon nitride, and aluminum nitride, or an insulating material such as resin.

The electrostatic attraction electrode 14 is made of a metal such as copper or titanium or a material such as TiN, TaN or WC.
Vapor deposition, metallization, plating, PV on the lower surface of the dielectric plate 12
D, formed by a method such as CVD.

The dielectric plate 12 constituting the suction surface 13 of the electrostatic chuck 11 is made of aluminum nitride containing cerium in the range of 2 to 20 mol% in terms of oxide (CeO ₂ ) and containing CeAlO ₃ phase. It is formed of a high quality sintered body. And this aluminum nitride-based sintered body is
Since it has a volume resistivity of 10 ⁸ to 10 ¹² Ω · cm in a temperature range of 0 ° C., the gap between the electrostatic chucking electrode 14 of the electrostatic chuck 11 and the fixed object 10 placed on the chucking surface 13. When a voltage is applied to the substrate, a minute leakage current flows between the object to be fixed 10 and the electrostatic attraction electrode 14, and the attraction force by the Johnson-Rahbek force can be developed.
In the temperature range of −50 ° C. to 200 ° C., the object 10 can be firmly adsorbed and held on the adsorption surface 13.

For this reason, even if the fixed object 10 is a warped substrate such as a semiconductor wafer or the like, it can be held in accordance with the accuracy of the suction surface 13. Exposure processing can be performed.

The energization of the electrostatic attraction electrode 14 is performed by using OF.
If F is set, the adsorption force can be immediately removed, so that the desorption response is excellent.

In addition, the electrostatic chuck 11 can be easily manufactured because the dielectric plate 12 and the base substrate 15 are separately manufactured, and only the bonding is performed with the bonding agent 16.

In this embodiment, an example of a monopolar electrostatic chuck has been described, but it is needless to say that the present invention can be applied to a bipolar electrostatic chuck.

[0052]

EXAMPLE An electrostatic chuck 1 of the present invention shown in FIG. 1 was manufactured as a prototype, and its adsorption characteristics at room temperature (25 ° C.) were measured.

First, a binder and a solvent were added to AlN powder having a purity of 99% and an average particle diameter of 1.2 μm to prepare a slurry, and then a plurality of green sheets having a thickness of about 0.5 mm were formed by a doctor blade method. They were laminated to form a molded body for forming the ceramic substrate 2. Then, on one main surface thereof, a tungsten paste containing 5% by volume of AlN powder was printed and applied by a screen printing method to form an electrode pattern forming the electrode 4 for electrostatic attraction.

On the other hand, an AlN powder having a purity of 99% and an average particle diameter of 1.2 μm and a CeN having a purity of 99% and an average particle diameter of 0.9 μm were used.
O ₂ powder and Al ₂ having a purity of 99% and an average particle size of 0.7 μm
O ₃ powder was mixed so that the composition of the compact was as shown in Table 1 by ICP analysis, and a binder and a solvent were added to produce a slurry.
A green sheet of about m was formed to obtain a formed body for the dielectric layer 3.

Then, on the surface of the metal film of the formed body for the ceramic substrate 2 provided with the metal film forming the electrode 4 for electrostatic adsorption, the formed body for the dielectric 3 is laminated, and the temperature is 80 ° C. and 50 kg / cm.
Thermocompression bonding was performed at a pressure of ² . Thereafter, the laminate is cut into a disk shape, degreased in vacuum, and then baked in a nitrogen atmosphere at a temperature of about 2000 ° C. for 3 hours, so that the outer diameter is 200 mm, the thickness is 8 mm, and the inner A plate-like body provided with a 15 μm electrostatic adsorption electrode 4 was formed. Then, the surface of the aluminum nitride ceramics constituting the dielectric layer 3 is polished to form the suction surface 5, and a hole communicating with the electrostatic suction electrode 4 is formed on the surface opposite to the suction surface 5. Then, a power supply terminal made of an iron-cobalt-nickel alloy is brazed to the hole to form an electrostatic chuck 1.
Was formed. For the obtained electrostatic chuck, room temperature (2
(5 ° C.), an 8-inch silicon wafer is placed on the suction surface 5 of the electrostatic chuck 1, and a voltage of 300 V is applied between the silicon wafer and the electrostatic chucking electrode 4 to suck the wafer onto the suction surface 5. In this state, the force required to peel the silicon wafer was measured as the attraction force. The results are shown in Table 1.

A ceramic having the same composition as that of the dielectric layer 3 was produced in the same manner as described above, and the volume resistivity at 0 ° C. to 50 ° C. was measured. Further, the density of the sintered body was measured by the Archimedes method, and the relative density (%), which is a ratio to the theoretical density, was calculated. Further, a precipitated crystal phase was identified from an X-ray diffraction chart on the surface of the sintered body. The thermal conductivity of the sample having a thickness of 2 mm was measured by a laser flash method. Further, the four-point bending strength at room temperature was measured according to JISR1601. The results are shown in Table 1.

[0057]

[Table 1]

As is clear from Table 1, Sample No. 1 in which the content of cerium (Ce) in the sintered body was less than 2 mol%. 1 and 2 have a small effect of lowering the resistance value,
The volume resistivity in the temperature range of 0 ° C. is 10 ⁸ to 10 ¹²
Ω · cm could not be obtained. The amount of Al ₂ O ₃ added is 50% of the amount of CeO ₂ in terms of molar equivalent.
Sample no. In No. 7, the volume specific resistance value was high, and when this was used as an electrostatic chuck, the suction force was 0 g / cm ² .

Further, the sample No. 13 shows that the content of cerium (Ce) in the aluminum nitride sintered body is 2
Because it was more than 0 mol%, strength and thermal conductivity decreased.

On the other hand, the sample within the scope of the present invention is 0
The volume resistivity in the temperature range of ~ 50 ° C is 10 ⁸ -1
0 ¹² Ω · cm, the relative density was 97% or more, the strength was 150 MPa or more, and the thermal conductivity was 30 W / mK or more. When these are used as electrostatic chucks, 5
High adsorption power of 0 g / cm ² or more could be obtained.

The sample No. in Table 1 was used. 4 (invention) and sample Nos. A ceramic (diameter 60 mm, thickness 2 mm) having the same composition as that of Comparative Example 1 (diameter 60 mm, thickness 2 mm) was produced under the same conditions as those of the above-mentioned electrostatic chuck, and this ceramic was prepared in vacuum for 4 hours.
After heating to 00 ° C., dry nitrogen was introduced, and a volume resistivity value at the time of temperature decrease was measured by a three-terminal method in a nitrogen atmosphere.
FIG. 3 shows the change of the volume resistivity value with respect to the temperature.

As is apparent from FIG. 3, there is a proportional relationship between the reciprocal of the temperature and the volume resistivity. 1
While the volume resistivity in the temperature range of 200 ° C. or lower of the comparative example exceeds 10 ¹³ Ω · cm, the sample No. which is within the range of the present invention. 4 (invention), -30 ° C to 100
The volume resistivity in the temperature range of 10 ° C. is 10 ⁸ to 10 ¹² Ω
cm.

[0063]

As described in detail above, the ceramic resistor of the present invention and the electrostatic chuck using the same can be used in the range of 0 to 50.
Since the volume resistivity at 10 ° C. is 10 ⁸ to 10 ¹² Ω · cm, it can be used in a wide temperature range because it can express the adsorption force by Johnson-Rahbek force even at a temperature of 200 ° C. or less. In addition, the object to be fixed can be firmly held with a high suction force.

Therefore, for example, when the electrostatic chuck of the present invention is used in a film forming process, a thin film having a uniform thickness can be coated on an object to be fixed and used in an exposure process and an etching process. For example, it is possible to perform accurate exposure and processing on the object to be fixed.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of an electrostatic chuck according to the present invention, wherein (a) is a perspective view and (b) is XX of (a).
It is a line sectional view.

FIGS. 2A and 2B are views showing another embodiment of the electrostatic chuck according to the present invention, wherein FIG. 2A is a perspective view, and FIG.
FIG. 3 is a sectional view taken along line Y.

FIG. 3 is a graph showing the relationship between the volume resistivity and the temperature of the aluminum nitride sintered bodies constituting the electrostatic chucks of the present invention and the comparative example.

[Explanation of symbols]

1. Electrostatic chuck 2. Ceramic substrate 3.
..Dielectric layer 4 ... Electrostatic adsorption electrode 5 ... Adsorption surface 6 ... Power supply terminal 10 ... Fixed object 11 ... Electrostatic chuck 12 ... Dielectric plate 13 ...
・ Suction surface 14 ・ ・ ・ Electrostatic attraction electrode 15 ・ ・ ・ Base substrate 1
6 ... bonding agent 17 ... power supply terminal

Claims (2)

[Claims] 1. An aluminum nitride as a main component, cerium in a range of 2 to 20 mol% in terms of oxide (CeO ₂ ), CeAlO ₃ , and a volume resistivity at 0 to 50 ° C. of 10%. A ceramic resistor having a resistivity of ⁸ to 10 ¹² Ω · cm. 2. An electrostatic chuck for adsorbing and holding an object to be fixed by electrostatic force, wherein an adsorption surface for adsorbing and holding the object to be fixed is mainly composed of aluminum nitride, and cerium is converted into oxide (CeO ₂ ). An electrostatic chuck containing 2 to 20 mol%, containing CeAlO ₃ , and having a volume resistivity at 0 to 50 ° C. of 10 ⁸ to 10 ¹² Ω · cm.