JP2001146475A - Carbon-containing aluminum nitride sintered compact - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aluminum nitride substrate sintered compact capable of securing at least >=108Ω..cm volume resistivity at a high temperature and guaranteeing opacifying properties, a large irradiation calorie and measurement accuracy by a thermoviewer. SOLUTION: This aluminum nitride sintered compact contains carbon in which a peak can not be detected at a position of 10-90 deg. reflection angle in an X-ray diffraction chart or is equal to or lower than the detection limit in a matrix composed of aluminum nitride.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a hot plate,
Aluminum nitride sintered body used mainly in the semiconductor industry as a material for components such as electrostatic chucks, wafer probers or susceptors, especially for the concealment of electrode patterns, volume resistivity at high temperatures, and temperature measurement accuracy with a thermoviewer The present invention relates to an excellent carbon-containing aluminum nitride sintered body.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor manufacturing and inspection apparatus including an etching apparatus and a chemical vapor deposition apparatus, a heater using a metal base material such as stainless steel or an aluminum alloy, a wafer prober, and the like have been used. Has been used. However, the metal heater has a problem that the temperature control characteristic is poor, and the thickness is large, so that the heater is heavy and bulky, and the corrosion resistance to corrosive gas is also poor.

On the other hand, Japanese Patent Application Laid-Open No. H11-40330 discloses a heater using a ceramic such as aluminum nitride instead of a metal heater. However, aluminum nitride itself, which is a base material of the heater, is generally white or gray-white, and is therefore not preferable as a heater or a susceptor. Rather, black is more suitable for this type of application because it has a higher radiant heat.
Further, since the electrode pattern has a high concealing property, it is particularly suitable for a wafer prober or an electrostatic chuck. Furthermore, the measurement of the surface temperature of the heater is performed by a thermoviewer (surface thermometer). However, in the case of white or gray white, the radiation amount is not constant, and accurate temperature measurement is impossible.

Among the conventional inventions described in Japanese Patent Application Laid-Open No. 9-48668 and the like developed in response to such demands,
44-45 ° on X-ray diffraction chart in ceramic substrate
The one to which crystalline carbon is added such that a peak is detected at the position (1) is proposed.

[0005]

However, such a conventional ceramic base material to which crystalline carbon (graphite) is added has a volume resistivity at a high temperature, for example,
Volume resistivity of 10 ⁸ Ω · c in the high temperature region of 500 ° C
m (see FIG. 1).

An object of the present invention is to solve the problems the prior art described above are having, as the volume resistivity at particular 500 ° C. of about at a high temperature of at least 10 ⁸
Ω · cm or more, and furthermore,
An object of the present invention is to provide an aluminum nitride sintered body that can guarantee a large amount of radiant heat and measurement accuracy by a thermoviewer. Another object of the present invention is to provide an aluminum nitride sintered body useful as a hot plate, an electrostatic chuck, a wafer prober, and a susceptor.

[0007]

SUMMARY OF THE INVENTION The present invention relates to an aluminum nitride sintered body developed to meet the above-mentioned demand, and more particularly, to a method of forming a matrix of aluminum nitride on an X-ray diffraction chart, wherein 2θ = 10. ~ 90
°, in particular, a carbon-containing aluminum nitride sintered body containing amorphous carbon in which a peak cannot be detected at a position of 44 to 45 ° or is below the detection limit.

In the present invention, the content of the carbon is preferably from 200 to 5000 ppm, and the color of the sintered body is preferably N4 or less in brightness defined by JIS Z 8721. .

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the study of the present inventors, the diffraction angle 2θ = 10 on the X-ray diffraction chart.
An aluminum nitride sintered body containing carbon such that a peak is detected at a position of about 90 to 90 °, particularly 2θ = 44 to 45 °, has a volume resistivity of 0.
Since it was reduced to 5 × 10 ⁷ Ω · cm, it was found that a short circuit occurred between the heating element patterns and between the electrode patterns during heating.

The reason is that the aluminum nitride sintered body is
In addition to a decrease in volume resistivity at high temperatures, crystalline carbon has a crystal structure similar to a metal crystal and has high electrical conductivity at high temperatures, so that these two properties act synergistically. Therefore, it is considered that such a short circuit is caused.

As a result of further study on this matter, the present inventors have found that in order to reduce the electrical conductivity of carbon at high temperatures, the crystallinity was reduced to such an extent that no peak was detected on the X-ray diffraction chart. Carbon or
It has been found that carbon dissolved in the crystal phase, that is, carbon whose peak is not detected on the X-ray diffraction chart may be used.

Here, the fact that no peak can be detected on the X-ray diffraction chart means that the diffraction angle 2θ is 10 to 90.
°, especially at 44 to 45 °, meaning that no carbon peak can be detected. It should be noted that various types of crystal systems exist in carbon as described above.
As disclosed in Japanese Patent No. 8668, not only a peak appearing at a diffraction angle 2θ = 44 to 45 ° but also a carbon crystal having a peak appearing at a diffraction angle 2θ = 10 to 90 ° must be considered. (FIGS. 2 and 3
reference).

In the X-ray diffraction chart, not only the peak but also the appearance of halo is not preferable. The amorphous body usually has a gentle undulation called a halo around 2θ = 15 to 40 °, but the appearance of such a halo means that amorphous carbon has penetrated into the aluminum nitride crystal phase. Means As a result, the crystallinity of the aluminum nitride is reduced, the sinterability is impaired, the brightness is increased, and the strength at high temperatures is also reduced.

As a specific method for producing carbon such that no peak can be detected on the X-ray diffraction chart, (1) carbon is dissolved in an aluminum nitride crystal phase to form a solid solution, and X-ray diffraction caused by the carbon crystal is performed. A method of preventing peaks, (2) a method using amorphous carbon, and the like can be considered.

Of these, the method (2) using amorphous carbon is preferred. The reason for this is that if carbon forms a solid solution in aluminum nitride, defects will occur in the crystals, resulting in a decrease in strength at high temperatures. Note that Japanese Patent Application Laid-Open No. 9-4866
Japanese Patent Application Laid-Open No. 9-4866 describes a phenomenon in which when heated at 1850 ° C., crystalline carbon dissolves in aluminum nitride and the peak of X-ray diffraction disappears.
In the invention described in Japanese Patent Publication No. 8 (KOKAI) No. 8, the invention in which the peak of X-ray diffraction exists at 44 to 45 ° is recognized as an invention, and the volume resistivity at a high temperature is described or suggested. Not.

The aluminum nitride sintered body of the present invention contains carbon and has a diffraction angle 2θ = 10 in the X-ray diffraction chart.
No peak appears at 90 ° and 25 to 500
Since the sintered body has a new physical property in which the volume resistivity at 10 ° C. becomes 10 ⁸ Ω · cm or more, see JP-A-9-4866.
No. 8, the novelty and inventive step of the present invention are not hindered at all.

In the present invention, the content of carbon whose peak cannot be detected on the X-ray diffraction chart or is below the detection limit is desirably 200 to 5000 ppm. If it is less than 200 ppm, it cannot be said that it is black, and the lightness exceeds N4.
If it exceeds pm, the sinterability of the aluminum nitride is reduced. In particular, 200 to 2000 ppm is optimal.

In the present invention, a matrix is formed.
The aluminum nitride sintered body should contain a sintering aid.
Is desirable. As the sintering aid, alkali metal acids
Use oxides, alkaline earth metal oxides, and rare earth oxides.
Especially CaO, Y _Two 0_Three , Na_Two 0, Li
_Two 0, Rb_Two 0_Three Is preferred. As the content, 0.1.
1 to 10% by weight is desirable.

Preferably, the aluminum nitride sintered body according to the present invention has a brightness of N4 or less as a value based on JIS Z 8721. This is because a material having such a lightness is excellent in radiant heat and concealing property. Here, the lightness N is defined as an ideal black lightness of 0,
The ideal white lightness is assumed to be 10, and each color is divided into 10 between the black lightness and the white lightness so that the perception of the brightness of the color becomes equal, and the symbols N0 to N10 are used. It is displayed. The actual measurement is performed by comparing the color charts corresponding to N0 to N10. In this case, the first decimal place is 0
Or it is set to 5.

In the aluminum nitride sintered body of the present invention,
An electrostatic electrode for an electrostatic chuck made of conductive metal or conductive ceramic may be embedded. FIG. 4 (a)
Is a longitudinal sectional view schematically showing an electrostatic chuck,
FIG. 2B is a cross-sectional view of the electrostatic chuck illustrated in FIG. In the electrostatic chuck 20, chuck positive / negative electrode layers 22, 23 are embedded in the aluminum nitride substrate 3, and a ceramic dielectric film 40 is formed on the electrodes. Further, a resistance heating element 11 is provided inside the aluminum nitride substrate 3 so that the silicon wafer 9 can be heated. Note that an RF electrode may be embedded in the aluminum nitride substrate 3 as necessary.

As shown in FIG. 2B, the electrostatic chuck 20 is usually formed in a circular shape in a plan view, and the inside of the aluminum nitride substrate 21 has a semi-circular portion 22a shown in FIG. Chuck positive electrode electrostatic layer 2 including comb teeth 22b
2 and the chuck negative electrode electrostatic layer 23, which also includes a semicircular arc-shaped portion 23 a and a comb tooth 23 b,
23b so as to intersect with each other.

When this electrostatic chuck is used, the positive and negative sides of a DC power supply are connected to the chuck positive electrostatic layer 22 and the chuck negative electrostatic layer 23, respectively, and a DC voltage is applied. Thus, the semiconductor wafer placed on the electrostatic chuck is electrostatically attracted.

FIGS. 5 and 6 are horizontal cross-sectional views schematically showing electrostatic electrodes in another electrostatic chuck.
In the electrostatic chuck 70 shown in FIG.
6, a semicircular chuck positive electrode electrostatic layer 72 and a chuck negative electrode electrostatic layer 73 are formed, and an electrostatic chuck 80 shown in FIG. Chuck positive electrostatic layers 82a, 82b
And chuck negative electrode electrostatic layers 83a and 83b are formed. Further, the two positive electrode electrostatic layers 82a and 82b and the two chuck negative electrode electrostatic layers 83a and 83b are formed to cross each other. In the case of forming an electrode in which a circular electrode or the like is divided, the number of divisions is not particularly limited, and may be five or more, and the shape is not limited to a sector.

Next, an example of the method for producing the aluminum nitride sintered body according to the present invention will be described. (1) First, an amorphous carbon is produced. For example, C,
A pure amorphous carbon is produced by calcining a hydrocarbon consisting of only H and O, preferably a saccharide (sucrose or cellulose) at 300 to 500 ° C in air. (2) Next, the above carbon and aluminum nitride powder to be a matrix component are mixed. The preferred size of the powder to be mixed is as small as about 0.1 to 5 μm in average particle size. This is because the finer the particle, the better the sinterability. The amount of carbon to be added is determined in consideration of the amount that disappears during firing. Further, a sintering aid such as the aforementioned yttrium oxide (yttria: Y ₂ O ₃ ) may be further added to the mixture.

Instead of the above treatments (1) and (2), a green sheet is prepared by mixing an aluminum nitride powder, a binder, a saccharide and a solvent, and then laminated. And the saccharides may be converted to amorphous carbon. In this case, both saccharides and amorphous carbon may be added.
In addition, as a solvent, α-terpineol, glycol, or the like can be used.

(3) Next, the obtained powder mixture is put into a molding die to form a molded product, or the above-mentioned green sheet laminate (both are temporarily calcined) is inerted with an inert gas such as argon nitrogen. 1700 ~ 1900 ℃, 80 ~
It is heated and pressed under the condition of 200 kg / cm ² for sintering.

In the aluminum nitride sintered body of the present invention, when the powder mixture is put into a molding die, a metal plate or a metal wire serving as a heating element is buried in the powder mixture or one of green sheets to be laminated. By forming a conductive paste layer serving as a heating element on a single green sheet, a ceramic heater using an aluminum nitride sintered body as a substrate can be manufactured. Further, after the sintered body is manufactured, a heating element can be formed on the bottom surface by forming a conductor paste layer on the surface (bottom surface) and baking the paste.

Further, at the time of manufacturing the ceramic heater, a metal plate or the like is embedded in the molded body so as to have an electrode shape such as an electrostatic chuck in addition to a heating element, or a conductive paste is placed on a green sheet. By forming layers, hot plates, electrostatic chucks, wafer probers,
Susceptors and the like can be manufactured.

The conductive paste for producing various electrodes and heating elements is not particularly limited, but contains metal particles or conductive ceramics for securing conductivity, as well as resins, solvents, and thickeners. And the like are preferred.

As the metal particles, for example, noble metals (gold, silver, platinum, palladium), lead, tungsten, molybdenum, nickel and the like are preferable. These may be used alone or in combination of two or more. This is because these metals are relatively hard to oxidize and have a resistance value sufficient to generate heat. Examples of the conductive ceramic include carbides of tungsten and molybdenum. These may be used alone or in combination of two or more.

The metal particles or conductive ceramic particles preferably have a particle size of 0.1 to 100 μm. 0.1μ
If the particle size is too small, it is easily oxidized.
If the thickness exceeds μm, sintering becomes difficult and the resistance value increases.

Although the shape of the metal particles is spherical,
It may be scaly. When these metal particles are used, they may be a mixture of the above-mentioned spheres and the above-mentioned flakes. When the metal particles are scaly, or a mixture of spherical and scaly, it is easy to hold the metal oxide between the metal particles, and the adhesion between the heating element and the nitride ceramic is improved. This is advantageous because it can be ensured and the resistance value can be increased.

As the resin used for the conductor paste,
For example, an epoxy resin, a phenol resin, and the like can be given. Examples of the solvent include isopropyl alcohol. Examples of the thickener include cellulose and the like.

When the conductor paste for the heating element is formed on the surface of the sintered body, a metal oxide is added to the conductor paste in addition to the metal particles, and the metal particles and the metal oxide are sintered. It is desirable that As described above, by sintering the metal oxide together with the metal particles, the aluminum nitride sintered body and the metal particles can be adhered to each other.

It is not clear why mixing metal oxide improves the adhesion to the aluminum nitride sintered body, but the surface of the metal particles and the surface of the aluminum nitride sintered body are slightly oxidized and oxidized. It is considered that a film is formed, and the oxide films are sintered and integrated through the metal oxide, and the metal particles and the nitride ceramic adhere to each other.

As the metal oxide, for example, oxidized
Lead, zinc oxide, silica, boron oxide (B _Two O_Three ), Al
Selected from the group consisting of Mina, Yttria and Titania
At least one is preferred.

This is because these oxides can improve the adhesion between the metal particles and the nitride ceramic without increasing the resistance of the heating element.

The ratio of the above-mentioned lead oxide, zinc oxide, silica, boron oxide (B ₂ O ₃ ), alumina, yttria, and titania is as follows: 1-10, silica 1-30, boron oxide 5-50, zinc oxide 20-70, alumina 1
-10, yttria 1-50, titania 1-50, and the total is preferably adjusted within a range not exceeding 100 parts by weight. By adjusting the amounts of these oxides in these ranges, the adhesion to the aluminum nitride sintered body can be particularly improved.

The amount of the metal oxide added to the metal particles is preferably 0.1% by weight or more and less than 10% by weight. The area resistivity when the heating element is formed using the conductor paste having such a configuration is preferably from 1 to 45 mΩ / □.

If the area resistivity exceeds 45 mΩ / □, the amount of heat generated becomes too large with respect to the applied voltage, and it is difficult to control the amount of heat generated in an aluminum nitride substrate provided with a heating element on the surface. . If the addition amount of the metal oxide is 10% by weight or more, the sheet resistivity exceeds 50 mΩ / □, the calorific value becomes too large, the temperature control becomes difficult, and the uniformity of the temperature distribution decreases. .

When the heating element is formed on the surface of the aluminum nitride substrate, it is desirable that a metal coating layer is formed on the surface of the heating element. This is to prevent the internal metal sintered body from being oxidized to change the resistance value. The thickness of the metal coating layer to be formed is preferably 0.1 to 10 μm.

The metal used for forming the metal coating layer is not particularly limited as long as it is a non-oxidizing metal, and specific examples thereof include gold, silver, palladium, platinum and nickel. . These may be used alone or 2
More than one species may be used in combination. Of these, nickel is preferred. In the case where the heating element is formed inside the aluminum nitride substrate, the surface of the heating element is not oxidized, and thus no coating is required.

[0043]

EXAMPLES Example 1 AlN + Y ₂ O ₃ + Amorphous Carbon (1) Sucrose was heated to 500 ° C. in an oxidizing air stream (in air) to be thermally decomposed to obtain amorphous carbon. . (2) 100 parts by weight of aluminum nitride powder (manufactured by Tokuyama Corporation, average particle size 1.1 μm), yttrium oxide (Y ₂ O
₃ : 4 parts by weight of yttria, average particle diameter 0.4 μm) and 0.09 parts by weight of the amorphous carbon of the above (1) were mixed, put into a mold, and placed in a nitrogen atmosphere at 1890 ° C. under a pressure of 150 kg.
/ Cm ² for 3 hours to obtain an aluminum nitride sintered body. The amount of carbon in the sintered body was measured by grinding the sintered body and heating it at 800 ° C.
This was done by collecting gas. As a result of measurement by this method, the amount of carbon contained in the aluminum nitride sintered body was 800 ppm. The lightness was N = 3.5.

Example 2 AlN + Amorphous Carbon (1) Sucrose was heated to 500 ° C. in the air to be thermally decomposed to obtain amorphous carbon. (2) 100 parts by weight of aluminum nitride powder (manufactured by Tokuyama Co., average particle size 1.1 μm) and 0.09 parts by weight of the amorphous carbon of the above (1) were mixed, put into a mold, and placed in a nitrogen atmosphere at 1890. Hot pressing was performed for 3 hours at a temperature of 150 ° C. and a pressure of 150 kg / cm ² to obtain an aluminum nitride sintered body. The amount of carbon in the obtained aluminum nitride sintered body was 805.
In ppm, the lightness was N = 3.5.

Example 3 Solid Solution of Carbon Aluminum Nitride Powder (manufactured by Tokuyama, average particle size 1.1)
μm), 100 parts by weight, 4 parts by weight of yttrium oxide (Y ₂ O ₃ : yttria, average particle diameter 0.4 μm), and 0.09 parts by weight of graphite (GR-1200, manufactured by Toyo Carbon Co., Ltd.) were mixed and formed into a mold. And hot-pressed at 1890 ° C. under a pressure of 150 kg / cm ² for 3 hours in a nitrogen atmosphere,
Further, this sintered body was heated at 1850 ° C. for 3 hours in a nitrogen atmosphere at normal pressure to cause graphite to form a solid solution in the aluminum nitride phase. The amount of carbon in the obtained aluminum nitride sintered body was 810 ppm, and the lightness was N = 4.0. It is considered that the solid solution phenomenon of carbon does not occur during the hot pressing.

(Comparative Example 1) AlN + Y ₂ O ₃ aluminum nitride powder (manufactured by Tokuyama Corporation, average particle size 1.1)
100 parts by weight) and 4 parts by weight of yttrium oxide (Y ₂ O ₃ : average particle diameter 0.4 μm) are mixed, put into a mold, and put in a nitrogen atmosphere at 1890 ° C. under a pressure of 150 k.
Hot pressing was performed for 3 hours under the condition of g / cm ² to obtain an aluminum nitride sintered body. The amount of carbon in the obtained aluminum nitride sintered body was 100 ppm or less, and the lightness was N = 7.
It was 0.

Comparative Example 2 AlN + Crystalline Carbon In this comparative example, phenol resin powder was used as a binder in accordance with the description in JP-A-9-48668.
In this prior art, the carbon obtained by decomposing the phenol resin and the acrylic binder is considered to be crystalline. First, 100 parts by weight of aluminum nitride powder (manufactured by Tokuyama Corporation, average particle size 1.1 μm) and 5 parts by weight of phenol resin powder are mixed, put into a mold, and placed in a nitrogen atmosphere at 1890 ° C. under a pressure of 150 kg / cm.
Hot pressing was performed under the conditions of ² for 3 hours to obtain an aluminum nitride sintered body. The amount of carbon in the obtained aluminum nitride sintered body was 810 ppm, and the lightness was N = 4.0.

FIG. 1 shows Examples 1 to 3 and Comparative Examples 1 and 2.
3 shows the transition of the volume resistivity from room temperature to 500 ° C. As shown in FIG. 1, in the example of the sintered body containing only the crystalline carbon shown as Comparative Example 2, the volume resistivity was reduced to about 1/10.

In the above measurement, the volume resistivity and the thermal conductivity were measured as follows. (1) Volume resistivity: cutting a sintered body into a shape having a diameter of 10 mm and a thickness of 3 mm, forming three terminals (main electrode, counter electrode, guard electrode), applying a DC voltage,
After reading the current (I) flowing through the digital electrometer after charging for 1 minute, the resistance (R) of the sample is determined, and the volume resistivity (ρ) is calculated from the resistance (R) and the dimensions of the sample by the following formula (1). ).

[0050]

(Equation 1)

In the above formula (1), t is the thickness of the sample. S is given by the following equations (2) and (3).

[0052]

(Equation 2)

[0053]

(Equation 3)

In the above formulas (2) and (3), r ₁ is the radius of the main electrode, r ₂ is the inner diameter (radius) of the guard electrode, r ₃ is the outer diameter (radius) of the guard electrode, D ₁ Is the diameter of the main electrode, D ₂ is the inner diameter (diameter) of the guard electrode, and D ₃ is the outer diameter (diameter) of the guard electrode. In this embodiment, 2r ₁ = D ₁ = 1.45 cm, 2r ₂ = D ₂ = 1.
60 cm, 2r ₃ = D ₃ = 2.00 cm.

FIGS. 2 and 3 show X-ray diffraction charts of the sintered body. The charts of the sintered bodies of Example 1 (FIG. 2) of the present invention and Comparative Example 2 (FIG. 3) are shown. Is shown. As shown in these figures, in the example of Embodiment 1, the diffraction angle 2θ = 1.
A carbon peak cannot be detected at a position of 0 to 90 °.
No halo appears at 2θ = 15 to 40 °.
However, in Comparative Example 2, a carbon peak is observed at a position of 2θ = 44 to 45 °.

FIG. 9 shows the results of measuring the strength of the sintered bodies of Examples 1 and 3. As shown in FIG. 9, the strength of the aluminum nitride sintered body in which carbon is dissolved is reduced. The strength was measured using an Instron universal tester (4507 load cell 500 kg).
f), in the air at a temperature of 25 to 1000 ° C., a crosshead speed of 0.5 mm / min, a span distance L = 30 mm,
Test specimen thickness = 3.06 mm, test specimen width = 4.03 m
m, and the three-point bending strength σ (kgf / mm ² ) was calculated using the following equation (4).

[0057]

(Equation 4)

In the above formula (4), P is the maximum load (kgf) when the test piece breaks, L is the distance between the lower supports (30 mm), and t is the thickness of the test piece. Sa (m
m) and w is the width (mm) of the test piece.

Further, the sintered bodies of Examples 1 to 3 and Comparative Examples 1 and 2 were heated to 500 ° C. on a hot plate, and the surface temperature was adjusted with a thermoviewer (Nihon Datum Co., Ltd.).
IR162012-0012) and JIS-C-160
2 (1980) type K thermocouple, and the temperature difference between the two was determined. It can be said that the larger the deviation from the temperature measured by the thermocouple, the larger the temperature error of the thermoviewer. According to the measurement results, the temperature difference was 0.8 ° C. in Example 1, 0.9 ° C. in Example 2, and 1.0 ° C. in Example 3.
° C, a temperature difference of 8 ° C in Comparative Example 1, and a temperature difference of 0 ° C in Comparative Example 2.
8 ° C.

Example 4 Application example, wafer prober (FIGS. 7 and 8) (1) 100 parts by weight of aluminum nitride powder (manufactured by Tokuyama Corporation, average particle size 1.1 μm), yttria (average particle size: 0.1 μm)
4 μm) 4 parts by weight, 0.2 part by weight of sucrose and 53% by weight of an alcohol composed of 1-butanol and ethanol
Was formed by using a composition obtained by mixing with a doctor blade method to obtain a green sheet 30 having a thickness of 0.47 mm. (2) After drying the green sheet 30 at 80 ° C. for 5 hours, punching was performed to provide through holes for through holes for connecting the heating element to external terminal pins.

(3) 100 parts by weight of tungsten carbide particles having an average particle diameter of 1 μm, acrylic binder 3.0
By weight, 3.5 parts by weight of an α-terpineol solvent and 0.3 parts by weight of a dispersant were mixed to prepare a conductive paste A.
Further, 100 parts by weight of tungsten particles having an average particle diameter of 3 μm, 1.9 parts by weight of an acrylic binder, 3.7 parts by weight of an α-terpineol solvent, and 0.2 parts by weight of a dispersant were mixed to prepare a conductive paste B. .

(4) The conductive paste A was printed on the surface of the green sheet 30 by a screen printing method to form a grid-shaped guard electrode print layer 50 and a ground electrode print layer 60. In addition, the conductive paste B was filled in the through-hole for through-hole for connecting to the external terminal connecting pin, thereby forming through-hole filling layers 160 and 170. Then, the green sheet 30 on which the conductive paste is printed and the green sheet 3 on which no printing is performed
50 sheets of 0 'were laminated and integrated at 130 ° C. under a pressure of 80 kg / cm ² (FIG. 7A).

(5) The integrated laminate is heated at 600 ° C. for 5 hours.
Degreasing for 1 hour, then 1890 ° C, pressure 150kg / c
Hot pressing was performed for 3 hours under the condition of m ² to obtain a 3 mm-thick aluminum nitride plate. This plate is 230m in diameter
An aluminum nitride substrate 3 was cut out in a circular shape of m (FIG. 7B). The size of the through holes 16 and 17 was 0.2 mm in diameter and 0.2 mm in depth. Also,
The thickness of the guard electrode 5 and the ground electrode 6 is 10 μm, and the formation position of the guard electrode 5 in the thickness direction of the sintered body is 1 mm from the heating element.
On the other hand, the formation position of the ground electrode 6 in the thickness direction of the sintered body was 1.2 mm from the chuck surface 1a.

(6) The aluminum nitride substrate 3 obtained in the above (4) is polished with a diamond grindstone, a mask is placed on the substrate, and the surface is blasted with glass beads to form a thermocouple mounting recess (not shown). ) And a groove 7 (0.5 mm width, 0.5 mm depth) for wafer suction (FIG. 7).
(C)).

(7) Further, a conductive paste was printed on the back surface opposite to the chuck surface 1a in which the groove 7 was formed to form a paste layer for a heating element. As the conductive paste, Solvest PS603D manufactured by Tokuri Chemical Laboratory, which is used for forming through holes in a printed wiring board, was used. That is, the conductive paste is a silver / lead paste, and a metal oxide composed of lead oxide, zinc oxide, silica, boron oxide, and alumina (the weight ratio of each is 5/55).
/ 10/25/5) is contained in an amount of 7.5% by weight based on the amount of silver. The silver in the conductive paste used was scaly with an average particle size of 4.5 μm.

(8) Aluminum nitride substrate (heater plate) having a heating element 41 formed by printing a conductive paste on the back surface
3 was heated and fired at 780 ° C. to sinter silver and lead in the conductive paste and baked the aluminum paste on the aluminum nitride substrate 3 to form a heating element 41 (FIG. 7D). Next, the aluminum nitride substrate 3 was treated with nickel sulfate 30 g /
1, boric acid 30 g / l, ammonium chloride 30 g / l,
It is immersed in an electroless nickel plating bath made of an aqueous solution containing 60 g / l of Rochelle salt, and further has a thickness of 1 μm and a boron content of 1% by weight or less on the surface of the heating element 41 made of the conductive paste. The heating element 41 was thickened by depositing a nickel layer 410, and then heat-treated at 120 ° C. for 3 hours. Nickel layer 410 thus obtained
The heating element 41 including the above has a thickness of 5 μm, a width of 2.4 mm, and a sheet resistivity of 7.7 mΩ / □. (9) Each layer of Ti, Mo, and Ni was sequentially laminated on the chuck surface 1a where the groove 7 was formed by a sputtering method. This sputtering uses SV-4540 manufactured by Nippon Vacuum Engineering Co., Ltd. as an apparatus, and has a pressure of 0.6 Pa and a temperature of:
The conditions were 100 ° C., power: 200 W, processing time: 30 seconds to 1 minute, and the sputtering time was adjusted according to each metal to be sputtered. The obtained film was obtained from the image of the X-ray fluorescence spectrometer with Ti of 0.3 μm, Mo of 2 μm, N
i was 1 μm.

(10) The aluminum nitride substrate 3 obtained in the above (9) was treated with 30 g / l of nickel sulfate and 30 g of boric acid.
g / l, ammonium chloride 30 g / l, Rochelle salt 6
A nickel layer having a boron content of 1% by weight or less (thickness: 7 μm) was immersed in an electroless nickel plating bath composed of an aqueous solution containing 0 g / l on the surface of the groove 7 formed on the chuck surface 1a. Precipitated and heat treated at 120 ° C. for 3 hours.
Further, an electroless gold plating solution composed of potassium gold cyanide 2 g / l, ammonium chloride 75 g / l, sodium citrate 50 g / l, and sodium hypophosphite 10 g / l on the surface (chuck surface side) of the aluminum nitride substrate 3. To 9
The aluminum nitride substrate 3 was immersed for 1 minute at 3 ° C.
On the nickel plating layer on the chuck side of
A chuck top conductor layer 2 was formed by laminating a gold plating layer of μm (FIG. 8E).

(11) Next, the air suction hole 8 that passes through the groove 7 to the back surface is drilled and drilled, and a blind hole 180 for exposing the through holes 16 and 17 is provided (FIG. 8F). . A Ni-Au alloy (A
u81.5 wt%, Ni 18.4 wt%, impurity 0.1
(wt%), and heated to reflow at 970 ° C. to connect the external terminal pins 19 and 190 made of Kovar (FIG. 8 (g)). The external terminal pins 1 made of Kovar are connected to the heating element 41 via a solder alloy (tin 9 / lead 1).
91 were formed. (12) In order to control the temperature, a plurality of thermocouples were buried in the recesses (not shown) to provide a heater with a wafer prober.

(13) Thereafter, usually, the heater with the wafer prober is usually fixed on a stainless steel support base via a heat insulating material made of ceramic fiber (manufactured by IBIDEN, trade name: IBIWOOL). A cooling gas injection nozzle is provided on the upper side to adjust the temperature of the wafer prober. The heater with a wafer prober sucks air from the air suction holes 8 to suck and support a wafer placed on the heater. Note that the heater with a wafer prober manufactured in this manner has a brightness of N =
3.5, which indicates that the amount of radiated heat is large and that the guard electrode 5 and the ground electrode 6 inside are excellent in concealment.

Example 5 Application Example, Ceramic Heater Having Heating Element and Electrostatic Electrode for Electrostatic Chuck Inside (FIG. 4) (1) Aluminum nitride powder (manufactured by Tokuyama Corporation, average particle size 1.1 μm) 100 Parts by weight, yttria (average particle size:
0.4 μm) A paste prepared by mixing 4 parts by weight, 0.09 parts by weight of the amorphous carbon obtained in Example 1, 0.5 parts by weight of a dispersant, and 53 parts by weight of an alcohol composed of 1-butanol and ethanol was used. The green sheet having a thickness of 0.47 mm was obtained by molding using a doctor blade method.

(2) Next, the green sheet was dried at 80 ° C. for 5 hours, and then punched with a diameter of 1.8 m.
A portion serving as a through hole for inserting a semiconductor wafer support pin having a length of 3.0 mm and 5.0 mm, and a portion serving as a through hole for connecting to an external terminal were provided.

(3) 100 parts by weight of tungsten carbide particles having an average particle diameter of 1 μm, 3.0 parts by weight of an acrylic binder, 3.5 parts by weight of an α-terpineol solvent, and 0.3 part by weight of a dispersant are mixed to form a conductor. Paste A was prepared.
A conductive paste B was prepared by mixing 100 parts by weight of tungsten particles having an average particle diameter of 3 μm, 1.9 parts by weight of an acrylic binder, 3.7 parts by weight of an α-terpineol solvent, and 0.2 parts by weight of a dispersant. The conductive paste A was printed on a green sheet by screen printing to form a conductive paste layer. The printing pattern was a concentric pattern.
Further, a conductor paste layer composed of an electrostatic electrode pattern having the shape shown in FIG. 4 was formed on another green sheet.

Further, a conductive paste B was filled in a through hole for a through hole for connecting an external terminal. On top of the green sheet after the above processing, a green sheet on which the tungsten paste is not printed is placed on the upper side (heating surface).
37 sheets at the bottom, 13 sheets at the bottom, 130 ° C, 80 kg / cm ²
The layers were laminated under the following pressure.

(4) Next, the obtained laminate is placed in nitrogen gas.
Degreasing at 600 ° C for 5 hours, 1890 ° C, pressure 150kg
/ Cm ² for 3 hours to obtain an aluminum nitride plate having a thickness of 3 mm. This was cut into a 230 mm disc to obtain a ceramic plate having a heating element of 6 μm thickness and a width of 10 mm and an electrostatic electrode inside. As a result of measuring the amount of carbon in this sintered body by the same measurement method as in Example 1, it was 810 ppm.

(5) Next, the plate-like body obtained in (4) is polished with a diamond grindstone, a mask is placed on the plate, and a bottomed hole for a thermocouple is formed on the surface by blasting with SiC or the like. (Diameter: 1.2 mm, depth: 2.0 mm).

(6) Further, a part of the through hole for the through hole is cut out to form a concave portion, and a Ni-Au gold solder is used in the concave portion, and reflow is performed by heating at 700 ° C. to form an external terminal made of Kovar. Connected. The connection of the external terminals is desirably a structure in which a tungsten support is supported at three points. This is because connection reliability can be ensured.

(8) Next, a plurality of thermocouples for temperature control were embedded in the bottomed holes, and the manufacture of the ceramic heater with the electrostatic chuck was completed. The heater with the electrostatic chuck manufactured in this way has a brightness of N = 3.5, has a large amount of radiant heat, and is excellent in concealment of the internal resistance heating element and the electrostatic electrode.

[0078]

As described above, since the aluminum nitride sintered body according to the present invention contains amorphous carbon, it has a high volume resistivity at a high temperature and a low brightness. Solidification is obtained. Further, accurate temperature measurement by a thermoviewer is possible. Therefore, the aluminum nitride sintered body of the present invention is useful, for example, as a substrate for a hot plate, an electrostatic chuck, a wafer prober, a susceptor and the like.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between ceramic substrate components and volume resistivity in Examples and Comparative Examples.

FIG. 2 is an X-ray diffraction chart of a sintered body of an example.

FIG. 3 is an X-ray diffraction chart of a sintered body of a comparative example.

4A is a longitudinal sectional view schematically showing an electrostatic chuck, and FIG. 4B is a sectional view of the electrostatic chuck shown in FIG.
FIG. 4 is a cross-sectional view taken along a line A.

FIG. 5 is a horizontal sectional view schematically showing another example of the electrostatic electrode embedded in the electrostatic chuck.

FIG. 6 is a horizontal sectional view schematically showing still another example of the electrostatic electrode embedded in the electrostatic chuck.

FIG. 7 is an explanatory diagram of a manufacturing process of a wafer prober made of an aluminum nitride sintered body.

FIG. 8 is an explanatory diagram of a manufacturing process of a wafer prober made of an aluminum nitride sintered body.

FIG. 9 is a graph showing temperature dependence of bending strength in Examples and Comparative Examples.

[Description of Signs] 2 chuck top conductor layer 3 aluminum nitride substrate 5 guard electrode 6 ground electrode 7 groove 8 air suction hole 16, 17 through hole 19, 190, 191 external terminal pin 20, 70, 80 electrostatic chuck 21, 71 , 81 Aluminum nitride substrate 22, 72, 82a, 82b Chuck positive electrostatic layer 23, 73, 83a, 83b Chuck v Negative electrostatic layer 41 Heating element 180

Claims (5)

[Claims] 1. A carbon-containing aluminum nitride sintered body characterized in that a matrix composed of aluminum nitride contains carbon whose peak cannot be detected on an X-ray diffraction chart or is below a detection limit. 2. The carbon whose peak cannot be detected on the X-ray diffraction chart or is below the detection limit is either amorphous carbon or carbon dissolved in an aluminum nitride crystal phase. Item 2. A carbon-containing aluminum nitride sintered body according to item 1. 3. The carbon content is 200 to 500.
The carbon-containing aluminum nitride sintered body according to claim 1 or 2, wherein the content is 0 ppm. 4. The method according to claim 1, wherein the matrix contains a sintering aid comprising at least one of an alkali metal oxide, an alkaline earth metal oxide and a rare earth oxide. The carbon-containing aluminum nitride sintered body according to any one of the above. 5. The carbon-containing aluminum nitride sintered body according to claim 1, wherein the brightness specified in JIS Z 8721 is N4 or less.