JP2002231796A - Electrostatic chuck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic chuck 1 which has a high attracting force and is excellent in detaching response of an object to be attracted. SOLUTION: In the electrostatic chuck 1, one main surface of a plate-like ceramic member 2 constituted of an aluminum nitride sintered body is made a setting surface 3 for mounting the object to be attracted, and an inner electrode 4 whose main component is metal is arranged in the plate-like ceramic member 2. The content of silicon in the aluminum nitride sintered body is set to be from 10 to 300 wt.ppm, and the amount of impurity oxygen is set at most 3 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to CVD, PVD,
The present invention relates to an electrostatic chuck for adsorbing and holding an object to be adsorbed such as a semiconductor wafer by electrostatic force in a film forming apparatus such as sputtering or an etching apparatus such as optical etching or plasma etching.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor device manufacturing process, an electrostatic chuck has been used to hold a wafer with high accuracy in a film forming process on a semiconductor wafer, an etching process, or a transfer between various processing processes. Have been.

As shown in FIGS. 4A and 4B, a conventional electrostatic chuck 51 has an upper surface of a plate-shaped ceramic body 52 serving as a mounting surface 53 on which an object W is placed. An internal electrode 54 for electrostatic attraction is embedded in the plate-shaped ceramic body 52, and an energizing terminal 55 electrically connected to the internal electrode 54 is fixed to the lower surface of the plate-shaped ceramic body 52. When a DC voltage of 100 to 1000 V is applied from a high-voltage DC power supply 58 between the energizing terminal 55 of the electrostatic chuck 51 and the adsorption object W placed on the installation surface 53, the adsorption object W and the installation surface 53 are applied. Therefore, the object to be attracted W is attracted and fixed to the installation surface 53 by the electrostatic attraction force.

Further, three holes 56 are formed in the periphery of the plate-shaped ceramic body 52, and the pin 5 is inserted through the holes 56.
7 can be moved up and down. Therefore, the electrostatic chuck 51
When the power to the object is stopped and the pin 57 is protruded from the installation surface 53, the object W is lifted up from the installation surface 53 and cut off.

However, when the object W is detached from the installation surface 53, the electric charge charged in the vicinity of the object W and the installation surface 53 does not immediately disappear even if the power supply to the electrostatic chuck 51 is stopped. Since a force that causes the object W to be attracted to the installation surface 53, that is, a residual suction force, is generated, if the object W is forcibly lifted by the pins 57 in such a state, the object If W is a thin plate such as a semiconductor wafer, there is a problem that it is damaged.

In order to shorten the time required for the object W to be detached, Japanese Unexamined Patent Application Publication No. 9-219441 discloses a method in which a conductive gas is supplied between the object W and the installation surface 53 so that the object W is separated from the object W. There has been proposed a technique for releasing charges accumulated on the installation surface 53.

Japanese Patent Application Laid-Open No. 2000-158275 discloses that a metal mesh is used as the internal electrode 54 for electrostatic attraction, and the ratio of the opening of the internal electrode 54 made of the metal mesh is 50% to 7%.
A technique has been proposed in which by setting the minimum width of the opening to 0.23 mm or more while keeping the opening width at 0%, the detachment property of the object W to be adsorbed is improved while maintaining a practically applicable adsorption force.

[0008]

In recent years, in the process of manufacturing semiconductor devices, it has been demanded to increase the productivity of semiconductor wafers. It is required to reduce the time to 10 seconds or less, preferably 5 seconds or less. However, according to the technique disclosed in Japanese Patent Application Laid-Open No. 9-219441, the electric charge charged on the wafer or the installation surface 53 is released and the pin 57 is released. 10 to lift without damaging the wafer
Seconds to 30 seconds.
Even with the technique disclosed in Japanese Unexamined Patent Application Publication No. 2005-163, it takes about 30 seconds to lift the wafer without being damaged by the pins 57, and no matter which technique is used, it takes 10 seconds without damaging the wafer.
It was difficult to withdraw within seconds.

[0009]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention provides a plate-like ceramic body made of an aluminum nitride sintered body, wherein one main surface is an installation surface on which an object to be adsorbed is placed. In an electrostatic chuck having an internal electrode containing a metal as a main component in a plate-shaped ceramic body, the silicon content contained in the aluminum nitride-based sintered body is set to 10 to 300 ppm by weight, and the impurity oxygen amount is increased. Is 3% by weight or less.

The internal electrode of the electrostatic chuck is formed by sintering particles of a high melting point metal or metal compound and particles of aluminum nitride, and has an average particle diameter of 0%. It is preferable to use one having a thickness of 0.2 μm to 100 μm.

[0011]

Embodiments of the present invention will be described below.

FIGS. 1A and 1B are views showing an electrostatic chuck according to the present invention, wherein FIG. 1A is a perspective view thereof, and FIG. 1B is a sectional view taken along line XX of FIG.

In the electrostatic chuck 1, an upper surface of a disk-shaped ceramic body 2 made of a disc-shaped aluminum nitride sintered body is used as an installation surface 3 on which an object to be adsorbed W is placed. In the vicinity of the installation surface 3 side, a pair of internal electrodes 4 having a semicircular shape as shown in FIG. The pair of internal electrodes 4 is provided on the lower surface of the ceramic body 2.
And the energizing terminals 5 electrically connected to each other. When a DC voltage of 100 to 1000 V is applied between the energizing terminals 5 of the electrostatic chuck 1 from the high-voltage DC power supply 8, an electrostatic attraction force is generated between the object W and the installation surface 3. The object W is placed on the installation surface 3 by the electroadsorption force.
It is designed to be fixed by suction.

The aluminum nitride sintered body forming the plate-shaped ceramic body 2 is exposed to a halogen-based gas or plasma because of its excellent corrosion resistance and plasma resistance to halogen-based gas containing fluorine and chlorine. Even if it is used in such an atmosphere, it can be used for a long period of time, and the aluminum nitride sintered body has a higher thermal conductivity than other ceramics. When heating or cooling the object to be sucked W, the temperature distribution on the processed surface of the object to be sucked W can be made uniform as compared with an electrostatic chuck made of another ceramic sintered body.

Although not shown, another electrode may be installed above the installation surface 3 and high-frequency power may be applied between this electrode and the internal electrode 4. Plasma can be generated for the object W to be adsorbed.

The pattern shape of the internal electrodes 4 embedded in the plate-shaped ceramic body 2 is not limited to that shown in FIG. 2A, but may be a single circle as shown in FIG. A plate-shaped internal electrode 4, a ring-shaped internal electrode 4 arranged concentrically as shown in FIG. 2C, and a fan-shaped as shown in FIG. 2D The internal electrodes 4 may be arranged so as to form a circle, or, as shown in FIG. 2 (e), the internal electrodes 4 in the form of comb teeth may be arranged with their teeth alternately arranged. Absent.
Further, as the properties of the internal electrode 4, various properties such as a film or a metal net obtained by sintering a metal powder, a metal foil plate or a metal foil plate having a large number of holes can be used.

Further, materials for forming the internal electrodes 4 include Ta (tantalum), W (tungsten), and Mo.
(Molybdenum), Pt (platinum), Re (rhenium), H
Although a high melting point metal such as f (hafnium) can be used, from the viewpoint of increasing the adhesion to the aluminum nitride sintered body forming the plate-shaped ceramic body 2, the thermal expansion difference from the aluminum nitride sintered body is increased. It is preferable to use W (tungsten) or Mo (molybdenum), which has a small value.

Further, the peripheral portion of the plate-shaped ceramic body 2 has 3
Three holes 6 are formed, and the pins 7 can be moved up and down through the holes 6. Therefore, by stopping the power supply to the electrostatic chuck 1 and making the pins 7 protrude from the installation surface 3, the object W can be lifted up from the installation surface 3 and separated.

In the electrostatic chuck 1 of the present invention, the silicon content in the aluminum nitride sintered body forming the plate-shaped ceramic body 2 is set to 10 ppm by weight to 300% by weight.
pm and the amount of impurity oxygen is 3% by weight or less.

That is, the inventor of the present invention has conducted researches in order to obtain an electrostatic chuck 1 having an electrostatic attraction force enough to be practically used and excellent in the detachment response of the object W to be sucked. As shown in the figure, it was found that a crack S parallel to the internal electrode 4 occurred at the boundary between the ceramic electrode P and the internal electrode 4. Many cracks S are formed at the boundary between the ceramic portion P on the installation surface 3 side and the internal electrode 4, or the cracks S are long in parallel with the installation surface 3.
In this case, the contact area between the ceramic portion P on the installation surface 3 side and the internal electrode 4 is reduced, and it is difficult for the electric charge charged near the installation surface 3 to escape to the internal electrode 4. Electric charges are charged in the vicinity, and the installation surface 3
To form a capacitor with the charge near
Since it is difficult for the electric charges in the vicinity of the installation surface 3 to escape, the electric charge in the vicinity of the installation surface 3 cannot be immediately released to the internal electrode 4 even if the supply of electric current to the internal electrode 4 is stopped. Knowing that it is not possible to enhance the detachment responsiveness of the electrode, at least to suppress the generation of cracks S that can be formed at the boundary between the ceramic portion P on the installation surface 3 side and the internal electrode 4,
As a result of repeating the study, it was found that the contents of silicon and impurity oxygen in the aluminum nitride sintered body forming the plate-shaped ceramic body 2 were significantly involved.

[0021] Here, silicon is contained as an impurity in the aluminum nitride sintered body, the oxygen combines with is believed to be present in the form of SiO _2, the SiO ₂ is 1500 ° C. or less It is considered that a liquid layer is generated at the temperature of and the effect of absorbing and relaxing the internal stress acting on the boundary between the internal electrode 4 and the ceramic portion P at the time of sintering is considered.

However, a part of silicon combines with a high melting point metal such as Mo (molybdenum) or W (tungsten) which forms the internal electrode 4 to form a silicide. Since the thermal expansion difference between the aluminum nitride sintered body forming the ceramic body 2 and the high melting point metal such as Mo (molybdenum) or W (tungsten) forming the internal electrode 4 is large, the silicon content is 300 ppm by weight. Exceed,
When the production amount of the silicon compound increases, stress acts on the boundary between the internal electrode 4 and the ceramic portion P, and many large cracks S are generated at this boundary.

When the silicon content is less than 10 ppm by weight, the proportion of silicon in the aluminum nitride sintered body is small, so that the stress acting on the boundary between the internal electrode 4 and the ceramic portion P during sintering is reduced. The absorption and relaxation effects are small,
Many large cracks S occur at the boundary between the internal electrode 4 and the ceramic portion P.

Therefore, as described above, the content of silicon contained in the aluminum nitride sintered body is 10 ppm by weight.
It is preferable that the content be from 300 to 300 ppm by weight.

In the present invention, the amount of impurity oxygen is the amount of oxygen excluding the amount of oxygen of the oxide added as an auxiliary for sintering or the like in the aluminum nitride sintered body. For example, as a component contained as a sintering aid of the aluminum nitride sintered body, an oxide of a group 2a element of the periodic table (CaO, SrO ₂ , BaO _2, etc.) such as Ca and a rare earth element such as Y are included. An oxide of a group 3a element of the periodic table (Y _{2
O 3, Er 2 O 3,} La 2 O 3, CeO 2 , etc.) is the is used, refers to a minus the amount of oxygen bound to the periodic table group 2a elements and the periodic table group 3a elements .

The amount of the impurity oxygen is defined by the fact that the impurity oxygen is combined with a high melting point metal such as Mo (molybdenum) or W (tungsten) which forms the internal electrode 4 and metal oxide is formed on the surface of the internal electrode 4. This metal oxide is also mixed with a high melting point metal such as an aluminum nitride sintered body forming the plate-shaped ceramic body 2 or Mo (molybdenum) or W (tungsten) forming the internal electrode 4. When the amount of impurity oxygen exceeds 3% by weight due to a large difference in thermal expansion, the amount of metal oxide generated on the surface of the internal electrode 4 becomes too large, so that a stress acts on the boundary with the ceramic portion P. This is because many large cracks S occur at the boundary.

Thus, the plate-shaped ceramic body 2 constituting the electrostatic chuck 1 is formed of an aluminum nitride sintered body having a silicon content of 10 to 300 wt ppm and an impurity oxygen amount of 3 wt% or less. Thus, the generation of cracks S at the boundary between the internal electrode 4 and the ceramic portion P can be effectively reduced. Can be immediately released to the internal electrode 4, so that the disappearance time of the residual adsorbing force can be shortened, and the detachment response of the object W can be improved.

The silicon content and the impurity oxygen content were measured by crushing an aluminum nitride sintered body using an alumina mortar and quantifying the total oxygen content using an EGMA-650A oxygen and nitrogen analyzer manufactured by Horiba, Ltd. analyse. In particular,
Using a graphite crucible as a heating furnace and flowing He gas for 100 hours
The amount of carbon dioxide generated by heating to a temperature of 0 ° C. or higher is detected and quantified by an infrared detector. Next, the ground powder is
5% HF / HNO ₃ mixed acid to melt and decompose by heating
All cations except l are converted to ICP (Inductively Coupled).
d Perform quantitative analysis by Plasma Atomic Emission Spectroscopy) analysis. Then, among the obtained cations, the amount of silicon was taken as the silicon content, and elements serving as sintering aids, such as Group 2a elements and Group 3a elements in the periodic table, were converted to oxides. The amount of oxygen at the time, that is, Ca oxide is CaO, Sr oxide is SrO ₂ , Ba oxide is B
The oxides of aO ₂ , Y, Er, La, and Ce are Y ₂ O ₃ , Er ₂
O ₃ , La ₂ O ₃ , and CeO ₂ were obtained, and the remaining oxygen amount subtracted from the total oxygen amount was defined as the impurity oxygen amount. In addition, Si
The generation of O _{2 and} the generation of the metal oxide forming the internal electrode 4 were confirmed by measuring the cross section of the electrostatic chuck 1 by EPMA analysis (wavelength dispersive X-ray microanalyzer). Can be determined from the fact that the concentrations of silicon and oxygen are high.

As the aluminum nitride sintered body forming the plate-shaped ceramic body 2, a material containing a sintering aid composed of an oxide of a group 2a element of the periodic table or an element of group 3a of the periodic table may be used. An aluminum nitride sintered body containing a sintering aid in this range preferably has a three-point bending strength of 250 MPa or more and a Vickers hardness of 9 GPa or more. It has a high thermal conductivity of 70 W / m · K or more, and is suitable for equalizing the temperature of the object W to be adsorbed and held, and forms the plate-shaped ceramic body 2. In the case of an aluminum nitride-based sintered body that does not contain a sintering aid and consists essentially of aluminum nitride except for silicon and impurity oxygen, the proportion occupied by the grain boundary layer in the sintered body is small. Aluminum Can further improve the corrosion resistance and plasma resistance of Um sintered body, it can also be a long electrostatic chuck 1 life as used under halogen gas or a plasma atmosphere.

When the internal electrode 4 is made of a film obtained by sintering high melting point metal particles such as W (tungsten) and Mo (molybdenum), the average particle diameter of the high melting point metal particles is 0.2 μm to 100 μm. It is good to be in the range. If the average particle size of the refractory metal is smaller than 0.2 μm, it easily reacts with the impurity oxygen contained in the aluminum nitride sintered body and forms a metal oxide layer on the surface of the refractory metal particles. However, since the metal oxide has a large thermal expansion difference with the high melting point metal or aluminum nitride, cracks are generated at the interface between the high melting point metal particles and the ceramic portion P when heating and cooling are repeated. On the other hand, if the average particle size of the high melting point metal exceeds 100 μm, it is difficult to form the internal electrode 4 having a uniform thickness, and a uniform electrostatic attraction force cannot be obtained. .
Preferably, the average particle size of the high melting point metal particles is 0.5 μm.
m to 100 μm.

In order to manufacture such an electrostatic chuck 1, it is important to use aluminum nitride powder containing little silicon or oxygen as a starting material, and the silicon content is at most 300 ppm by weight or less. It is preferable to select one containing at most 3% by weight or less of impurity oxygen.

To the aluminum nitride powder, a sintering aid comprising an oxide of a Group 2a element or a Group 3a element of the periodic table is added, if necessary, and an organic binder is added. A milling ball made of alumina or silicon nitride is added and kneaded. At this time, the crushed balls are worn and abrasion powder is mixed in. When the silicon content in the starting material is relatively large, the starting material is made of alumina or silicon nitride having as few impurities as possible, particularly having a low silicon content. It is preferable to use a pulverized ball, and when the silicon content in the starting material is small, the abrasion rate of alumina containing silicon within a range where the silicon content does not exceed 5% by weight is 1000 ppm / hour or less. Or a crushed ball made of silicon nitride having an abrasion wear rate of 10 ppm / hour or less.

A plate-like ceramic body in which the internal electrodes 4 are embedded by using the kneaded material as slurry or granulated powder and using ceramic forming means such as a tape forming method, a casting method, a press forming method, a hot pressing method or the like. 2 is made.

For example, when a tape forming method, a casting method, or a press forming method is used as the ceramic forming means, a plurality of AlN green sheets are manufactured by a tape forming method, and several AlN green sheets are laminated. The internal electrode 4 is arranged thereon. Here, when a metal mesh or a metal foil plate is used as the internal electrode 4, what is processed into a predetermined pattern shape may be arranged at a predetermined position, and when a film in which metal powder is sintered is used as the internal electrode 4, A conductive paste in which a solvent and an organic binder are mixed with a metal powder may be printed at a predetermined position so as to have a predetermined pattern shape.

Next, the remaining A is covered so as to cover the internal electrodes 4.
1N green sheets are stacked and thermocompressed, and the inner electrodes 4
To produce a plate-like green sheet laminate having embedded therein.
Here, when a film obtained by sintering a metal powder is used as the internal electrode 4, the pressure at the time of thermocompression bonding is preferably 3 to 15 MPa. This is because if the pressure is 3 MPa or less, the metal particles and the AlN green sheet do not physically adhere to each other, and cracks are easily generated at the interface.
If it is larger than Pa, the ceramic laminate is deformed, and the outer diameter of the internal electrode 4 changes, so that it cannot be controlled to a desired size.

Thereafter, the obtained ceramic laminate is fired to produce the plate-like ceramic body 2 in which the internal electrodes 4 are buried. In firing, the maximum temperature is 1750-2200 ° C. It is preferable to hold at the maximum temperature for 1 hour or more.

Here, the maximum temperature is 1750-2200 ° C.
The reason is that if the maximum temperature is lower than 1750 ° C., it is difficult to densify, and if the maximum temperature is higher than 2200 ° C., abnormal grain growth of aluminum nitride crystals occurs, and the aluminum nitride sintered body This is because the mechanical properties (three-point bending strength, Vickers hardness, and the like) of the material are greatly reduced. The reason why the holding time at the highest temperature is set to 1 hour or more is that the impurity oxygen in the AlN green sheet is reacted with carbon of the organic binder and released to the outside as a CO gas. If less than one hour,
This is because excessive impurity oxygen contained in the AlN green sheet cannot be sufficiently released as CO gas, and the amount of impurity oxygen cannot be reduced to 3% by weight or less. However, if the holding time at the maximum temperature is too long, it is uneconomical. Therefore, the holding time may be at most 10 hours.

When a hot pressing method is used as the ceramic molding means, the granulated powder is filled in a mold, and a molded body is formed by press molding. Then, the internal electrode 4 is arranged on the molded body. Here, when a metal mesh or a metal foil plate is used as the internal electrode 4, what is processed into a predetermined pattern shape may be arranged at a predetermined position, and when a film in which metal powder is sintered is used as the internal electrode 4, A conductive paste in which a solvent and an organic binder are mixed with a metal powder may be printed at a predetermined position so as to have a predetermined pattern shape.

Next, after filling the remaining granulated powder into the mold so as to cover the internal electrodes 4, the plate-shaped ceramics in which the internal electrodes 4 are embedded are subjected to uniaxial pressing at a high temperature by a hot press method. The body 2 is manufactured. When firing, the firing temperature is set to 1750 to 2200 ° C. and 5MP
It is preferable to pressurize at a pressure of not less than a for 1 hour or more, and preferably pressurize at a pressure of 10 MPa or more for not less than 2 hours.

Here, the firing temperature is 1750-2200 ° C.
The reason for this is that if the firing temperature is lower than 1750 ° C., it is difficult to densify. If the firing temperature exceeds 2200 ° C., abnormal grain growth of aluminum nitride crystals occurs, and the aluminum nitride-based sintered body This is because there is an inconvenience that the mechanical properties (three-point bending strength, Vickers hardness, etc.) of the No. 1 are significantly reduced. If the pressure is 5 MPa or more, if the pressure is less than 5 MPa, it is difficult to densify, and cracks S are formed at the boundary between the ceramic portion P and the internal electrode 4.
This is because there is an inconvenience that liability is likely to occur. further,
The reason why the pressurization time is set to 1 hour or more is that impurity oxygen in the AlN green sheet reacts with carbon of the organic binder,
If the pressurization time is less than 1 hour, the excess impurity oxygen contained in the AlN green sheet cannot be sufficiently released as a CO gas because the CO2 gas is released to the outside. Cannot be less than 3% by weight. However, if the holding time at the maximum temperature is too long, it is uneconomical.

By manufacturing the plate-shaped ceramic body 2 as described above, the silicon content in the aluminum nitride sintered body forming the plate-shaped ceramic body 2 is 10 to 300 ppm by weight, and the amount of impurity oxygen is reduced. It can be 3% by weight or less.

Thereafter, one main surface of the obtained plate-shaped ceramic body 2 is polished, and the surface roughness thereof is adjusted to an arithmetic average roughness (Ra) of 1 μm or less, whereby the material W to be adsorbed is obtained.
Is formed, a hole communicating with the internal electrode 4 is formed in the other main surface of the plate-shaped ceramic body 2, and a current-carrying terminal 5 is inserted into the hole and joined by means such as brazing. Can be obtained.

The electrostatic chuck 1 of the present invention is not limited to the one having the structure shown in the present embodiment, but may be an improved or modified one without departing from the gist of the present invention. Needless to say.

[0044]

(Embodiment 1) Here, an electrostatic chuck 1 as shown in FIGS. 1A and 1B using a wire mesh for an internal electrode 4 was prepared, and a plate-like ceramic body 2 of the electrostatic chuck 1 was prepared. An experiment was conducted to examine the desorption responsiveness of the adsorbed substance when the silicon content and the impurity oxygen content in the aluminum nitride-based sintered body for forming porosity were varied.

First, an aluminum nitride powder having an average particle size of about 1 μm manufactured by a reduction nitriding method was prepared as a starting material, and calcium oxide powder was used as a sintering aid at 1% by weight and yttrium oxide powder at 0.5% by weight. While adding
A granulated powder was produced by adding alumina powder and colloidal silica powder having an average particle size of about 1 μm in different amounts, further adding ethanol and a binder, and kneading and drying. The obtained granulated powder was filled in a mold, and a disc-shaped preform having a diameter of 200 mm and a thickness of 6 mm was manufactured by press molding. After that, a wire mesh made of a molybdenum wire was formed on the preform. A molded product having a thickness of 15 mm is placed on which a product processed so as to have a pattern shape shown in FIG. 2 (a) is placed, the remaining granulated powder is filled thereon, and the internal electrode 4 is buried by press molding. Was made.

The internal electrode 4 has a wire diameter of 0.5.
mm, a wire mesh having a square opening shape and an aperture ratio of about 65% was used.

Next, the obtained molded body was placed in a carbon hot press mold, and uniaxially pressed.
After setting the vacuum atmosphere to 0 ° C. and heating at a temperature rising rate of 5 ° C./min, introducing nitrogen gas, setting the nitrogen atmosphere to 1750 ° C., heating at a rate of 8 ° C./min, and heating at a temperature of 1750 ° C. After holding for the time shown in Table 1, further 5 ° C to 1900 ° C
The temperature was raised at a rate of 1 / min, and the temperature was kept at 1900 ° C. for 3 hours to produce a disc-shaped plate-shaped ceramic body 2.

At this time, the density of the aluminum nitride sintered body as a sample piece formed under the same conditions as the plate-shaped ceramic body 2 was measured by the Archimedes method.

Next, the obtained plate-shaped ceramic body 2 is polished by a rotary polishing machine using a diamond grindstone to a thickness of 4 mm, an outer diameter of 200 mm by a universal polishing machine, and further to a machining center. Three through holes 6 each having a hole diameter of 5 mm
And a hole for supplying an electrode having a hole diameter of 3 mm is formed in one main surface of the plate-shaped ceramic body 2.
The electrostatic chuck 1 was manufactured by individually perforating, inserting a current-carrying terminal 5 into a hole for supplying an electrode, and fixing it by brazing.

The electrostatic chuck 1 manufactured as described above
Is placed in a vacuum device having a degree of vacuum of 0.1 Pa, and a pin having a contact-type sensor embedded therein is installed in one of the holes 6 penetrating the electrostatic chuck 1 so as to be able to move up and down. Was supplied with He gas at a pressure of 600 Pa.

Then, a silicon wafer is placed on the installation surface 3 of the electrostatic chuck 1 as an object to be attracted,
A voltage of 0 V is applied to develop an electrostatic attraction force, and the silicon wafer is attracted and fixed to the installation surface 5.
After the power supply to the space is cut off, the silicon wafer is pressed by the pin 7 with a force of 15 N, and the time until the silicon wafer separates from the installation surface 3 is measured three times. Time.

After that, the internal electrode 4 was
And the cut surface is scanned with a scanning electron microscope (S
EM) was observed at a magnification of 1000 times, and the presence and size of cracks at the boundary between the ceramic portion on the installation surface 3 side and the internal electrode 4 were observed. The results are as shown in Table 1.

[0053]

[Table 1]

As a result, Sample No. 3,4,7,8,1
0, 11, 12, 13, 16, the aluminum nitride sintered body forming the plate-shaped ceramic body 2 has a silicon content of 10 to 300 ppm by weight and an impurity oxygen content of 3% by weight. In the following range, the size of the crack at the boundary between the ceramic part on the installation surface 3 side and the internal electrode 4 is 1 μm or less in width and 20 μm in length.
As a result, the detachment time of the silicon wafer was as short as 10 seconds or less, and the detachment response was excellent.

(Embodiment 2) Next, an electrostatic chuck 1 as shown in FIGS. 1A and 1B using a film obtained by hardening metal particles for an internal electrode 4 is prepared. An experiment was conducted to examine the desorption response of the adsorbed substance when the silicon content and the impurity oxygen content in the aluminum nitride sintered body forming the plate-shaped ceramic body 2 were varied.

First, an aluminum nitride powder having an average particle size of about 1 μm manufactured by a reduction nitriding method was prepared as a starting material, and a calcium oxide powder and a yttrium oxide powder were used as sintering aids in an amount of 1% by weight and 0.5% by weight, respectively. While adding
A slurry was prepared by adding alumina powder and colloidal silica powder having an average particle size of about 1 μm in different amounts, further adding polyvinyl butyral as a binder, and toluene and xylene as solvents, and mixing in a ball mill.

Next, the obtained slurry was treated with a doctor blade method to form an A 250 mm on a side and 300 μm thick.
Eleven 1N green sheets were produced.

On the other hand, a conductive paste was prepared by mixing polyvinyl butyral resin and terpineol with tungsten powder, and the resulting conductive paste was screen-printed on the upper surface of several stacked AlN green sheets as shown in FIG. Then, the remaining AlN green sheets were stacked and thermocompression-bonded at a temperature of 70 ° C. to produce a ceramic laminate in which the conductive paste forming the internal electrodes 4 was embedded.

Next, after the obtained ceramic laminate was heated to 500 ° C. in a vacuum atmosphere to perform a degreasing treatment, it was placed in a BN firing pot in a carbon firing furnace, and 1200 mm in a vacuum atmosphere. After the temperature was raised to 5 ° C./min at a rate of 5 ° C./min, nitrogen gas was introduced, the temperature was raised to 1750 ° C. at a rate of 8 ° C./min in a nitrogen atmosphere, and the temperature was maintained at 1750 ° C. for the time shown in Table 2. Thereafter, the temperature was further increased to 1980 ° C. at a rate of 5 ° C./min, and the temperature was maintained at 1980 ° C. for 3 hours to produce a disc-shaped plate-shaped ceramic body 2.

At this time, the density of the aluminum nitride sintered body as a sample piece formed under the same conditions as the plate-shaped ceramic body 2 was measured by the Archimedes method.

Next, the obtained plate-shaped ceramic body 2 is polished by a rotary polishing machine using a diamond grindstone to a thickness of 4 mm, an outer diameter of 200 mm by a universal polishing machine, and further to a machining center. Three through holes 6 each having a hole diameter of 5 mm
And a hole for supplying an electrode having a hole diameter of 3 mm is formed in one main surface of the plate-shaped ceramic body 2.
The electrostatic chuck 1 was manufactured by individually perforating, inserting a current-carrying terminal 5 into a hole for supplying an electrode, and fixing it by brazing.

The electrostatic chuck 1 manufactured as described above
Is placed in a vacuum device having a degree of vacuum of 0.1 Pa, and a pin having a contact-type sensor embedded therein is installed in one of the holes 6 penetrating the electrostatic chuck 1 so as to be able to move up and down. Was supplied with He gas at a pressure of 600 Pa.

Then, a silicon wafer as an object to be attracted is placed on the installation surface 3 of the electrostatic chuck 1, and 5
A voltage of 00 V is applied to develop an electrostatic attraction force, and the silicon wafer is attracted and fixed to the installation surface 3. After 10 seconds, the current between the energizing terminals 5 is cut off. The time until the silicon wafer was detached from the installation surface 3 was measured three times, and the average value was taken as the detachment time of the object. Then, it is cut in a direction perpendicular to the internal electrode 4 with a diamond grindstone, and the cut surface is observed at a magnification of 1000 times with a scanning electron microscope (SEM). And the size of cracks at the boundary of, and the average particle size of the tungsten particles forming the internal electrode 4 were observed. The results are as shown in Table 2.

[0064]

[Table 2]

As a result, as shown in FIG. 20, 23, 24,
27, 28, 29, 31;
The average particle size of the tungsten particles forming the internal electrode 4 is such that the silicon content in the aluminum nitride sintered body forming the internal electrode 4 is in the range of 10 wt ppm to 300 wt ppm and the amount of impurity oxygen is 3 wt% or less. Is 0.2 to 10
In the range of 0 μm, the size of the cracks at the boundary between the ceramic portion on the installation surface 3 side and the internal electrode 4 is as small as 1 μm or less in width and 20 μm or less in length. Was as short as 10 seconds or less and excellent in withdrawal response.

[0066]

As described above, according to the present invention, one main surface of a plate-like ceramic body made of an aluminum nitride sintered body is used as an installation surface on which an object to be adsorbed is placed, and In the electrostatic chuck provided with an internal electrode containing a metal as a main component in the body, the silicon content in the aluminum nitride-based sintered body is set to 10 ppm by weight to 30% by weight.
0 ppm by weight and the amount of impurity oxygen is 3% by weight.
By setting as follows, the object to be attracted can be detached within 10 seconds by stopping the supply of electricity to the electrostatic chuck while maintaining the electrostatic attraction force having a magnitude that can be practically used. Can be greatly increased.

Therefore, if the electrostatic chuck of the present invention is used in a film forming process or an etching process on a semiconductor wafer, it is possible to perform a film forming or etching process with high accuracy and to stop energizing the electrostatic chuck. Since the semiconductor wafer can be immediately removed, the time until the next semiconductor wafer is processed can be shortened, and the productivity of semiconductor devices can be improved.

[Brief description of the drawings]

FIG. 1 is a view showing an example of an electrostatic chuck according to the present invention;
(A) is its perspective view, (b) is XX sectional drawing of (a).

FIGS. 2A to 2E are plan views showing various pattern shapes of an internal electrode.

FIG. 3 is a schematic cross-sectional view in which the vicinity of a boundary between a ceramic portion and an internal electrode on the installation surface side when the electrostatic chuck is cut is enlarged.

FIG. 4 is a view showing an example of a conventional electrostatic chuck, and FIG.
Is a perspective view thereof, and (b) is a sectional view taken along line YY of (a).

[Explanation of symbols]

1, 51: electrostatic chuck 2, 52: plate-shaped ceramic body 3, 53: installation surface 4, 54: internal electrode 5, 55: energizing terminal 6, 56:
Hole 7, 57: Pin 8, 58: Power supply P: Ceramic part S: Crack

Claims (2)

[Claims] 1. A plate-shaped ceramic body made of an aluminum nitride-based sintered body has one main surface as an installation surface on which an object to be adsorbed is mounted, and an internal electrode containing a metal as a main component in the plate-shaped ceramic body. Wherein the silicon content in the aluminum nitride sintered body is 10
An electrostatic chuck having a weight ppm of 300 to 300 ppm by weight and an impurity oxygen amount of 3% by weight or less. 2. The internal electrode according to claim 1, wherein said high melting point metal or metal compound particles and aluminum nitride particles are sintered, and said high melting point metal or metal compound has an average particle diameter of 0.2.
2. The electrostatic chuck according to claim 1, wherein the electrostatic chuck is in a range of μm to 100 μm.