JP2001181050A - Carbon-containing aluminum nitride sintered compact - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aluminum nitride sintered compact having at least >=108 Ω.cm volume resistivity at high temperatures and capable of ensuring >=60 W/m.k thermal conductivity at the high temperatures and further assuring hiding properties, large radiant heat quantity and measuring accuracy with a thermoviewer. SOLUTION: This carbon-containing aluminum nitride sintered compact is characterized as comprising the carbon having the peaks appearing at about 1,580 cm-1 and about 1,355 cm-1 in >3.0 peak intensity ratio of I (1,580)/I (1,355) of the peak at about 1,580 cm-1 to the peak at about 1,355 cm-1 in an analysis with a laser Raman spectrum in the aluminum nitride.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a hot plate,
Electrostatic chuck, as a constituent material such as a wafer prober or a susceptor, related to aluminum nitride sintered body mainly used in the semiconductor industry, in particular, concealment of electrode patterns, volume resistivity and thermal conductivity at high temperature, and The present invention proposes a carbon-containing aluminum nitride sintered body having excellent temperature measurement accuracy using a thermoviewer.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor manufacturing and inspection apparatus including an etching apparatus, a chemical vapor deposition apparatus, and the like, a heater using a metal base material such as stainless steel or an aluminum alloy, a wafer prober, or the like is conventionally used. I have been. 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 proposes 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.
In addition, 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, radiant heat is also measured, so that accurate temperature measurement was 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, the conventional ceramic substrate to which such crystalline carbon (graphite) is added has a volume resistivity at high temperature of, for example, 10 ° C. in a high temperature region of 200 ° C. or more. There was a problem that it was reduced to less than ⁸ Ω · cm. In addition, there is a problem that aluminum nitride itself has reduced thermal conductivity in a high temperature region, and it is necessary to solve this problem. Further, it is necessary to keep the fracture toughness value from decreasing while maintaining the volume resistivity and the thermal conductivity at a high temperature.

An object of the present invention is to solve the above-mentioned problems of the prior art. In particular, the volume resistivity in a high temperature region of 200 ° C. or more (for example, around 500 ° C.) is at least 10 ⁸ Ω · cm. The thermal conductivity at high temperature is 60 W / m · k or more, and the fracture toughness value is 2.5 MPam
^An object of the present invention is to provide an aluminum nitride sintered body that can secure ^を or more and can guarantee concealing properties, large radiant heat, and measurement accuracy by a thermoviewer. Also,
Another object of the present invention is to provide a hot plate, an electrostatic chuck,
An object of the present invention is to provide an aluminum nitride sintered body useful as a wafer prober, a susceptor, and the like.

[0007]

Means for Solving the Problems The present invention relates to aluminum nitride sintered body developed to meet the above requirements, in particular, in the aluminum nitride, in the analysis by laser Raman spectrum, 1580 cm ^-1 and around 1
A peak appears around 355 cm ^-1 and 1580 cm ^-1
-1 near the peak intensity ratio of the peak and 1355 cm ^-1 vicinity of the peak of: I (1580) / I ( 1355) is 3.0
It is characterized by containing more than carbon. Also,
Full width at half maximum of the peak around 1355 cm ^-1 (full width at half maximum)
Is desirably 20 cm ⁻¹ or more.

In the present invention, the amount of carbon is
The content is preferably 200 to 5000 ppm. It is preferable that the aluminum nitride contains at least one of an alkali metal oxide, an alkaline earth metal oxide, and a rare earth oxide, and JIS Z 8
It is preferable to use a carbon-containing aluminum nitride sintered body having a brightness defined by 721 of N4 or less.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION According to the study of the inventors,
On the X-ray diffraction chart, in particular, 2θ = 44 to 45 °
Since the volume resistivity at high temperature (200 ° C. or more) decreases to 0.5 × 10 ⁷ Ω · cm, the aluminum nitride sintered body containing carbon whose peak is detected at the position It has been found that a short circuit occurs between the heating element patterns and between the electrode patterns and a leak current occurs.

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. It is considered that the above-mentioned short circuit is caused.

The inventors of the present invention have continued their research to obtain an aluminum nitride sintered body having a large volume resistivity capable of preventing such a short circuit. It has been found that in order to increase the volume resistivity in the above, carbon having reduced crystallinity may be added.

However, it has also been found that the addition of carbon having reduced crystallinity to aluminum nitride causes a problem that the thermal conductivity at high temperatures is reduced. this is,
It is presumed that amorphous carbon probably acts as a barrier interfering with the particle interface and hindering the propagation of heat. The inventors have found that such a problem can be solved by using carbon having both crystalline and amorphous properties.

When carbon containing both crystalline and amorphous properties is contained, the sintered body has excellent properties such as volume resistivity and thermal conductivity at high temperatures, No reduction in toughness was observed, and in the analysis of the sintered body by laser Raman spectrum, 158
0 cm ^-1 near the peak intensity ratio of the peak and 1355 cm ^-1 vicinity of the peak of: I (1580) / I ( 1355) is found to exceed 3.0, in which the present invention has been completed. In addition, "around 1580 cm ^-1 ""1355c
The expression "near m ^-1 " is used because an error is expected in Raman shift, and
^-1 , meaning a peak appearing at 1355 cm ^-1 .

Here, first, the laser Raman spectrum analysis of the carbon material will be described. Raman spectrum refers to the spectrum of scattered light that appears due to the Raman effect. When a substance is irradiated with monochromatic light having a constant frequency, the scattered light has a different wavelength from the radiated light. Is included.

When a carbon material is irradiated with a laser beam of a predetermined wavelength, a Raman effect occurs and a laser Raman spectrum is observed. Since the Raman spectrum is light generated in association with crystal vibrations, etc. A spectrum having a wavelength depending on crystallinity can be detected.

That is, in the case of crystalline carbon (graphite or the like), a spectrum is detected at around 1580 cm ⁻¹ , and a part of the crystal lattice of the crystalline carbon becomes amorphous, or When carbon is mixed, a peak is detected even at around 1355 cm ^-1 . Therefore, around 1580 cm ^-1 and 1355
Carbon in which peaks are detected near both cm ⁻¹ can be said to be carbon having relatively low crystallinity.

The peak near 1580 cm ^-1 and 1
Peak intensity ratio with the peak near 355 cm ^-1 : I (15
80) / I (1355) is larger, the crystallinity is higher. The peak near 1355 cm ^-1 indicates amorphousness, and the greater the half width, the higher the amorphousness. In the present invention, the lower limit of the crystallinity of carbon is defined as the peak intensity ratio: I
The value of (1580) / I (1355) is set to 3.0, and the crystallinity and the amorphousness are both improved while the crystallinity is slightly increased. Further, the upper limit of the amorphous property is 1355
20 cm ^{-1 in} the half width (full width at half maximum) of the peak near cm ^-1
By doing so, the crystallinity can be prevented from becoming too high.

As described above, when carbon containing both crystalline and amorphous properties is contained, the volume resistivity at high temperature is at least 10 ⁸ Ω · cm and the thermal conductivity at high temperature is reduced. It can be 60 W / m · k or more, and can overcome the problems of the prior art. Furthermore, since the peak intensity ratio: I (1580) / I (1355) is 3.0 or more, the crystallinity is slightly high, and a decrease in fracture toughness can be suppressed. The reason why the decrease in the fracture toughness can be suppressed is not clear, but it is estimated that the growth of cracks may be suppressed by highly crystalline carbon.

In the analysis by the laser Raman spectrum, peaks were detected at around 1580 cm ^{-1 and} around 1355 cm ^-1 , and a peak intensity ratio: I (1580) / I
Although a specific method for obtaining a ceramic substrate containing carbon having (1355) exceeding 3.0 is not particularly limited, the following method is preferable.

That is, the acid value is 0.3 to 1.0 KOHmg.
/ G of an acrylic resin is mixed with a ceramic raw material, molded, and then decomposed at a temperature of 350 ° C. or more in an inert atmosphere (nitriding gas, argon gas) to be carbonized and thermally decomposed. After being thermally decomposed, it is heated and pressed to obtain an aluminum nitride sintered body. The reason why carbon having both crystallinity and amorphousness can be obtained by using such an acrylic resin is not clear, but an acrylic resin having an acid value of 0.3 to 1.0 KOHmg / g is not available. It is presumed that, since it is easily thermally decomposed and carbonized, carbonization proceeds while cutting the amorphous skeleton of the acrylic resin, so that the crystallinity is likely to be increased. Further, since the acrylic resin having an acid value of 0.3 to 1.0 KOH mg / g is easily thermally decomposed, it is desirable to adjust the blending amount to 8 to 20% by weight based on the raw material powder. The acrylic resin having an acid value of 0.3 to 1.0 KOHmg / g preferably has a Tg point of 40C to 60C. The weight average molecular weight is desirably from 10,000 to 50,000.

Further, the acrylic resin is acrylic acid,
A copolymer comprising at least one of acrylic acid esters and / or at least one of methacrylic acid and methacrylic acid esters is desirable. Commercial products of such an acrylic resin include SA-54 manufactured by Mitsui Chemicals, Inc.
There are 5 series. This series has an acid value of 0.5-1.
The ones with 0 KOHmg / g are available.

Further, the aluminum nitride sintered body of the present invention has a
80 cm ^-1 vicinity of the peak and 1355 cm ^-1 vicinity of the peak intensity ratio of the peaks of: I (1580) / I ( 1355) is contained with the crystalline carbon and amorphous carbon, such as greater than 3.0, In addition, since the sintered body has new physical properties in which the volume resistivity at 25 to 500 ° C. becomes 10 ⁸ Ω · cm or more, the present invention is based on the conventional technology such as Japanese Patent Application Laid-Open No. 9-48668. Gender and inventive step are not hindered at all.

In Japanese Patent Application Laid-Open No. 9-48668,
Although it is described that graphite may be used, crystalline graphite shows a peak only at 1580 cm ⁻¹ in a laser Raman spectrum,
In Japanese Patent Application Laid-Open No. 9-48668, the present invention is considered to be graphite having high crystallinity analyzed by X-ray diffraction.

Analysis by laser Raman spectrum shows 15
80 cm ^-1 near the peak intensity ratio of the peak and 1355 cm ^-1 vicinity of the peak of: I (1580) / the I (1355) is 3.0 or less, 500 ° C. under the influence of amorphous carbon The thermal conductivity in the nearby high-temperature region decreases.

The half width of the peak near 1355 cm ^-1 (full width at half maximum) in the analysis by the laser Raman spectrum.
However, if it is less than 20 cm ⁻¹ , the decrease in volume resistivity in a high temperature region of 200 ° C. or higher may not be sufficiently suppressed due to the crystallinity of carbon. 13
The half width (full width at half maximum) of the peak near 55 cm ⁻¹ is 45
It is preferably at least cm ⁻¹ .

In the present invention, the amount of the carbon added is desirably 200 to 5000 ppm. 2
If it is less than 00 ppm, it cannot be said that it is black, and the lightness exceeds N4. On the other hand, if the addition amount exceeds 5000 ppm, the sinterability of aluminum nitride decreases.

In the present invention, the aluminum nitride sintered body
It is desirable to include a sintering aid therein. Its sintering
Auxiliaries include alkali metal oxides and alkaline earth metals
Oxides and rare earth oxides can be used, especially Ca
O, Y_Two O_Three , Na_Two O, Li _Two O, Rb_Two O_Three Is preferred
It is. The content is preferably 0.1 to 10% by weight.
No. Also, alumina may be added.

Preferably, the aluminum nitride sintered body according to the present invention has a brightness of N4 or less as a value based on the provisions of JIS Z 8721. This is because a material having such a lightness is excellent in radiant heat and concealing property. In addition, such a sintered body is formed by a thermoviewer.
Accurate surface temperature measurement becomes possible.

Here, the lightness N is defined as 0 for an ideal black lightness, 10 for an ideal white lightness, and a brightness of the color between these black lightness and white lightness. Each color is divided into ten so that the perception of the color is equal, and displayed by symbols N0 to N10. And the actual measurement is N0-N
The comparison is made with the color chart corresponding to No. 10. In this case, the first decimal place is 0 or 5.

The aluminum nitride sintered body of the present invention has a disk shape, preferably has a diameter of 200 mm or more, and has a diameter of 250 mm or more.
m or more is optimal. This is because a disk-shaped semiconductor manufacturing apparatus / inspection substrate is required to have uniform temperature, but a substrate having a larger diameter tends to have a non-uniform temperature.

The thickness of the aluminum nitride sintered body of the present invention is preferably 50 mm or less, more preferably 20 mm or less. Further, 1 to 5 mm is optimal. If the thickness is too small, warpage at a high temperature is apt to occur, and if the thickness is too large, the heat capacity becomes too large and the temperature rise and fall characteristics deteriorate.
The porosity of the aluminum nitride sintered body of the present invention is 0.
Or 5% or less is desirable. Reduced thermal conductivity at high temperatures,
This is because the occurrence of warpage can be suppressed.

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. 7A is a longitudinal sectional view schematically showing an electrostatic chuck, and FIG. 7B is a sectional view taken along line AA of the electrostatic chuck shown 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. The aluminum nitride substrate 3 may have an RF
Electrodes may be embedded. 7B, the electrostatic chuck 20 is usually formed in a circular shape in plan view, and inside the aluminum nitride substrate 21, a semicircular portion 22a and a comb-tooth portion shown in FIG. The chucking positive electrode electrostatic layer 22 composed of a semi-circular portion 23a and the comb tooth portion 23b is opposed to each other so as to cross the comb tooth portions 22b and 23b. Are located.

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. 8 and 9 are horizontal sectional views schematically showing electrostatic electrodes of another electrostatic chuck.
In the electrostatic chuck 70 shown in FIG.
A semi-circular chuck positive electrode electrostatic layer 72 and a chuck negative electrode electrostatic layer 73 are formed inside 1. 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 a method for producing the above aluminum nitride sintered body according to the present invention will be described. (1) An acrylic resin having an acid value of 0.3 to 1.0 KOH mg / g and aluminum nitride powder 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, the above mixture further contains the above-mentioned yttrium oxide (yttria: Y ₂ O).
_A sintering aid such as ₃ ) may be added.

(2) Next, the obtained powder mixture is put into a molding die to form a molded body, and the molded body is thermally decomposed at 350 ° C. or higher to carbonize the acrylic resin. Instead of the treatment of (1) and (2) above, aluminum nitride powder, acid value is 0.3 ~
A green sheet is prepared by mixing 1.0 KOH mg / g of an acrylic resin and a solvent, and then laminated, and the green sheet laminate is preliminarily fired at 300 to 600 ° C. to obtain carbon as the carbon used in the present invention. Good. In addition, as a solvent, α-terpineol, glycol, or the like can be used.

(3) Next, a molded product obtained by carbonizing an acrylic resin or a laminate of the above green sheets (both are temporarily calcined) is heated at 1600 to 1900 ° C. in an inert atmosphere such as argon nitrogen. 80-200 kg / cm ²
And sintering by heating and pressing. The sintering temperature is 1
As the temperature approaches 900 ° C., the crystallinity increases and the peak intensity ratio I (1580) / I (1355) increases, so that the peak intensity ratio can be adjusted at the sintering temperature.

In the aluminum nitride sintered body of the present invention, when a powder mixture is put into a molding die, a metal plate (foil) or a metal wire serving as a heating element is buried in the powder mixture or a green sheet to be laminated. By forming a conductive paste layer serving as a heating element on one of the green sheets, 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 this ceramic heater, a metal plate (foil) or the like is buried inside the molded body so as to have the shape of an electrode such as an electrostatic chuck in addition to the heating element, or a green sheet is formed. By forming a conductive paste layer on a substrate, a hot plate, an electrostatic chuck, a wafer prober, a susceptor, 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.

Even if 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 value of the heating element.

The ratio of the above lead oxide, zinc oxide, silica, boron oxide (B ₂ O ₃ ), alumina, yttria, and titania is such that, when the total amount of the metal oxide is 100 parts by weight, the lead oxide is in a weight ratio. 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 heat value becomes too large with respect to the applied voltage, and it is difficult to control the heat value 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.

When a metal layer is formed on the surface of the aluminum nitride sintered body or when a coating layer is formed on the metal layer, physical vapor deposition such as sputtering may be used in addition to the above-mentioned application of the conductor paste. Means and chemical coating means such as plating can be employed.

[0056]

EXAMPLES Example 1 (1) 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 12 parts by weight of an acrylic resin binder (SA-545 manufactured by Mitsui Chemicals, Inc., acid value 0.5 KOHmg / g) were mixed and put into a mold to form a molded article. did. (2) The molded body was heated in a nitrogen atmosphere at 350 ° C. for 4 hours to thermally decompose the acrylic resin binder. (3) The molded body was heated at 1890 ° C. and a pressure of 150 kg / cm ^2.
Was hot pressed for 3 hours to obtain an aluminum nitride sintered body. The amount of carbon in the sintered body was measured by pulverizing the sintered body and heating it at 500 to 800 ° C.
_Performed by collecting _x gas. As a result of measurement by this method, the amount of carbon contained in the aluminum nitride sintered body was 800 ppm. The brightness is N = 3.5.
Met.

FIG. 3 is a laser Raman spectrum showing the results of laser Raman spectroscopy analysis of the sintered body obtained in Example 1, and the measurement conditions were microscopic Raman (JOBIN YVON RAMAN).
OR U-100), laser power: 200 mW, laser beam diameter: 20 μm, excitation wavelength: 514.5 nm,
Slit width: 1000 μm, gate time: 1,
repeat time: 4, temperature: 25.0 ° C. To as laser Raman spectrum is apparent from that shown FIG. 3, 1580 cm clearly peaks around ^-1 and around 1355 cm ^-1 were observed, it can be seen that crystallinity is carbon decreased. Peak intensity ratio I (1580)
In /I(1355)=4.0, half-value width of the peak of 1355 cm ^-1 is 70cm ^-1.

Example 2 (1) 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 10 parts by weight of an acrylic resin binder (SA-545 manufactured by Mitsui Chemicals, Inc., acid value: 1.0 KOHmg / g) were mixed and put into a molding die to form a molded article. did. (2) The molded body was heated in a nitrogen atmosphere at 600 ° C. for 1 hour to thermally decompose the acrylic resin binder. (3) The molded body was heated at 1890 ° C. and a pressure of 150 kg / cm ^2.
Was hot pressed for 3 hours to obtain an aluminum nitride sintered body. The amount of carbon in the sintered body was measured by pulverizing the sintered body and heating it at 500 to 800 ° C.
_Performed by collecting _x gas. As a result of measurement by this method, the amount of carbon contained in the aluminum nitride sintered body was 810 ppm. The brightness is N = 3.5.
Met.

FIG. 4 is a laser Raman spectrum showing the results of laser Raman spectroscopy analysis of the sintered body obtained in the present Example 2, and the measurement conditions were microscopic Raman (JOBIN YVON RAMAN).
OR U-100), laser power: 200 mW, laser beam diameter: 20 μm, excitation wavelength: 514.5 nm,
Slit width: 1000 μm, gate time: 1,
repeat time: 4, temperature: 25.0 ° C. The laser Raman spectrum As is apparent from that shown FIG. 4, is clearly a peak around 1580 cm ^-1 and near 1355 cm ^-1 was observed, while maintaining the crystal system, and amorphous broken part of the crystal You can see that there is. Peak intensity ratio I (1580) / I (1355) =
At 3.8, the half width of the peak at 1355 cm ^-1 is 45 cm
It is ^-1 .

Comparative Example 1 (1) 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 an average particle diameter of 0.4 μm) was mixed with crystalline graphite (GR-1200 manufactured by Toyo Carbon Co., Ltd.) 0.10
The parts by weight were mixed and placed in a mold to obtain a molded body. (2) The molded body was heated at 1900 ° C. and a pressure of 150 kg / cm ^2.
Was hot pressed for 3 hours to obtain an aluminum nitride sintered body. The amount of carbon contained in the aluminum nitride sintered body was 800 ppm. The brightness is N = 3.5.
Met.

FIG. 6 is a laser Raman spectrum showing the results of laser Raman spectroscopy analysis of the sintered body obtained in Comparative Example 3. The measurement conditions were microscopic Raman (JOBIN YVON RAMAN).
OR U-100), laser power: 200 mW, laser beam diameter: 20 μm, excitation wavelength: 514.5 nm, slit width: 1000 μm, gate time: 1, r
Eat time: 4, temperature: 25.0 ° C.
Laser Raman spectroscopy of aluminum nitride sintered body
A peak was observed only at 1580 cm ^-1 .

Comparative Example 2 (1) 100 parts by weight of aluminum nitride powder (manufactured by Tokuyama Corporation, average particle size 1.1 μm), yttrium oxide (Y ₂ O)
₍₃ : average particle size: 0.4 μm) 4 parts by weight were mixed and put into a molding die to obtain a molded product. (2) The molded body was heated at 1900 ° C. and a pressure of 150 kg / cm ^2.
Was hot pressed for 3 hours to obtain an aluminum nitride sintered body. The amount of carbon contained in the aluminum nitride sintered body was 50 ppm or less, and was estimated to be carbon originating from the raw material. The brightness was N = 7.0.

Comparative Example 3 (1) 100 parts by weight of aluminum nitride powder (manufactured by Tokuyama Corporation, average particle size 1.1 μm), acrylic resin binder (manufactured by Kyoeisha KC-600, trade name: acid value 17 KOHmg)
/ G) 8 parts by weight were mixed and put into a mold to obtain a molded body. (2) The molded body was heated in a nitrogen atmosphere at 600 ° C. for 1 hour to thermally decompose the acrylic resin binder. (3) The molded body was heated at 1890 ° C. and a pressure of 150 kg / cm ^2.
Was hot pressed for 3 hours to obtain an aluminum nitride sintered body. The amount of carbon in the obtained aluminum nitride sintered body was 805 ppm, and the lightness was N = 3.5.

FIG. 5 is a laser Raman spectrum showing the result of laser Raman spectroscopy analysis of carbon contained in the sintered body obtained in Comparative Example 3, and is shown by micro-Raman (JOBIN YVON).
RAMANOR U-100), laser power: 200m
W, laser beam diameter: 20 μm, excitation wavelength: 514.5
nm, slit width: 1000 μm, gate tim
e: 1, repeat time: 4, temperature: 25.0
° C.

[0065] from the laser Raman spectrum shown in FIG. 5, to measure the height of the peak around the peak and 1355 cm ^-1 in the vicinity of 1580 cm ^-1, the peak intensity ratio: I (158
0) / I (1355) was 2.1. Was also 45cm ^-1 as measured half width of the peak around the 1355 cm ^-1 (FWHM). Therefore, the sintered body of Comparative Example 3 was mostly amorphous carbon.

FIG. 1 shows Examples 1 and 2 and Comparative Examples 1 to 3.
2 shows changes in 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 1, the volume resistivity was reduced to about 1/10.

FIG. 2 shows the temperature dependence of the thermal conductivity of the sintered body. The carbon having the peak intensity ratio I (1580) / I (1355) = 2.1 shown as Comparative Example 3 was not used. In the example, the thermal conductivity was reduced to 60 W / mk.

Further, the sintered bodies of Examples 1 and 2 and Comparative Examples 1 to 3 were heated to 500 ° C. on a hot plate, and the surface temperature was adjusted with a thermoviewer (IR162012-0012, manufactured by Nippon Datum Co., Ltd.) 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. As a result, the temperature difference was 0.8 ° C. in Example 1, 0.9 ° C. in Example 2, 0.8 ° C. in Comparative Example 1, 8 ° C. in Comparative Example 2, and 8 ° C. in Comparative Example 3. The difference was 0.9 ° C.

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). ).

[0070]

(Equation 1)

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

[0072]

(Equation 2)

[0073]

(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.

(2) Thermal conductivity: a. Equipment used Rigaku laser flash method thermal constant measurement device LF / TCM-FA8510B b. Test conditions Temperature: room temperature, 200 ° C, 400 ° C, 500 ° C, 70
0 ° C atmosphere ... vacuum c. Measurement method-Temperature detection in the specific heat measurement was performed by a thermocouple (platinel) bonded to the back surface of the sample with a silver paste. The room temperature specific heat measurement was further performed in a state where a light receiving plate (glassy carbon) was adhered to the upper surface of the sample via silicon grease, and the specific heat (Cp) of the sample was obtained by the following formula (4).

[0076]

(Equation 4)

In the above equation (4), ΔO is the input energy, ΔT is the saturation value of the temperature rise of the sample, Cp
_Gc is the specific heat of glassy carbon, W _Gc is the weight of glassy carbon, Cp _SG is the specific heat of silicon grease, W _SG is the weight of silicon grease, and W is the weight of the sample.

The fracture toughness values of the ceramic heaters of Examples 1 and 2 and Comparative Examples 1 to 3 were measured. The results are shown in Table 1. In the above measurement, the fracture toughness value was obtained by measuring the length of a crack generated by pressing an indenter into the surface with a Vickers hardness tester (MVK-D type manufactured by Akashi Seisakusho), and calculating the following formula (5). Calculated using

Fracture toughness = 0.026 × E ^1/2 × 0.5 × P ^1/2 × a × C ^-3/2 (5)

In the above formula (5), E is the Young's modulus (3.18 × 10 ¹¹ Pa), and P is the indentation load (9
8N), a is half (m) the average length of the indentation diagonal, C
Is half the average crack length (m).

[0081]

[Table 1]

Example 4 Application example, wafer prober (FIGS. 10 and 11) (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)
Using a composition obtained by mixing 4 parts by weight), 4 parts by weight, 10 parts by weight of an acrylic resin binder (SA-545 manufactured by Mitsui Chemicals, Inc., acid value: 1.0 KOH mg / g), and 53% by weight of alcohol composed of 1-butanol and ethanol. 0.47m thick by molding using blade method
m green sheets 30 were obtained. (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-like 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
Fifty sheets of 0 ′ were laminated and integrated at 130 ° C. under a pressure of 80 kg / cm ² (FIG. 10A). (5) The integrated laminate was pyrolyzed at 600 ° C. for 1 hour, and then hot-pressed at 1890 ° C. and a pressure of 150 kg / cm ² for 3 hours to obtain an aluminum nitride plate having a thickness of 3 mm. . This plate was cut into a circular shape having a diameter of 230 mm to form an aluminum nitride substrate 3 (FIG. 10).
(B)). The size of the through holes 16 and 17 was 0.2 mm in diameter and 0.2 mm in depth. 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 sintered body thickness direction is 1 mm from the heating element, while the formation of the ground electrode 6 in the sintered body thickness direction is performed. The position 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 (width 0.5 mm, depth 0.5 mm) for wafer suction (FIG. 1).
0 (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, this 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 has an average particle size of 4.
A 5 μm scale was used.

(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. 10D). Then
This aluminum nitride substrate 3 was treated with 30 g of nickel sulfate /
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 having a thickness of μm (FIG. 11E). (11) Next, the air suction hole 8 that escapes from the groove 7 to the back surface is drilled and drilled.
A hole 180 for exposing the bag is provided (FIG. 11).
(F)). A Ni-Au alloy (Au8
1.5 wt%, Ni 18.4 wt%, impurities 0.1 wt%
%), And heated and reflowed at 970 ° C. to connect the external terminal pins 19 and 190 made of Kovar (FIG. 11 (g)). Further, the external terminal pins 19 made of Kovar are connected to the heating element 41 via a solder alloy (tin 9 / lead 1).
1 was 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 a wafer prober is usually fixed on a stainless steel support base through a heat insulating material made of ceramic fiber (trade name, IBIDEN, manufactured by IBIDEN Co., Ltd.). A cooling gas injection nozzle is provided on the table 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. 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, the thermal conductivity is high, and the internal guard electrode 5 and the ground electrode 6 are excellent in concealment. In addition, a decrease in volume resistivity at high temperatures can be suppressed,
No short circuit occurs during operation, and leakage current can be reduced.

Example 5 Application Example, Ceramic Heater Having Heating Element and Electrostatic Electrode for Electrostatic Chuck Inside (FIG. 7) (1) Aluminum nitride powder (manufactured by Tokuyama, average particle size 1.1 μm) 100 Parts by weight, yttria (average particle size:
0.4 μm) 4 parts by weight, acrylic resin binder (SA-545 manufactured by Mitsui Chemicals, acid value 1.0 KOHmg / g) 10
Using a composition obtained by mixing 53 parts by weight of alcohol consisting of 1 part by weight and 1-butanol and ethanol, the mixture was molded by a doctor blade method to a thickness of 0.47.
mm green sheet was obtained.

(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. 7 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.
Pyrolyzed at 350 ° C for 4 hours, 1890 ° C, pressure 150k
By hot pressing at g / cm ² for 3 hours, an aluminum nitride plate having a thickness of 3 mm was obtained. This was cut out into a disk shape of 230 mm to obtain a plate-shaped body made of aluminum nitride having a heating element having a thickness of 6 μm and a width of 10 mm and an electrostatic electrode therein.

(5) Next, the plate-like body obtained in (4) is polished with a diamond grindstone, a mask is placed on the plate, and blast processing using SiC or the like is performed on the surface to form bottomed holes for thermocouples. (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 recess, and a gold solder made of Ni—Au is used in the recess, and heated and reflowed 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, a high thermal conductivity, and is excellent in concealment of the internal resistance heating element and the electrostatic electrode. . Further, a decrease in volume resistivity at a high temperature can be suppressed, and no short circuit or leak current occurs during operation. In the present example, the leak current could be reduced to less than 10 mA at a voltage of 1 kV at 400 ° C.

[0097]

As described above, since the aluminum nitride sintered body according to the present invention contains two types of carbon which are complementary to each other, the aluminum nitride sintered body is excellent in the concealability of the electrode pattern and the temperature measurement accuracy by the thermoviewer. An aluminum nitride sintered body having excellent volume resistivity and thermal conductivity at high temperatures and low brightness. Further, the fracture toughness value is not reduced. 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 a relationship between temperature and volume resistivity of aluminum nitride sintered bodies in Examples and Comparative Examples.

FIG. 2 is a graph showing the influence of the thermal conductivity of a sintered body in Examples and Comparative Examples.

FIG. 3 is a laser Raman spectrum showing the result of laser Raman spectroscopic analysis of carbon contained in the sintered body obtained in Example 1.

FIG. 4 is a laser Raman spectrum showing the result of laser Raman spectroscopic analysis of carbon contained in the sintered body obtained in Example 2.

FIG. 5 is a laser Raman spectrum showing the result of laser Raman spectroscopic analysis of carbon contained in the sintered body obtained in Comparative Example 3.

FIG. 6 is a laser Raman spectrum showing the result of laser Raman spectroscopic analysis of carbon contained in the sintered body obtained in Comparative Example 1.

7A is a longitudinal sectional view schematically showing an electrostatic chuck, and FIG. 7B is a sectional view of the electrostatic chuck shown in FIG.
FIG. 4 is a cross-sectional view taken along a line A.

FIG. 8 is a horizontal cross-sectional view schematically illustrating another example of the electrostatic electrode embedded in the electrostatic chuck.

FIG. 9 is a horizontal sectional view schematically showing still another example of the electrostatic electrode embedded in the electrostatic chuck.

FIG. 10 is an explanatory diagram of a manufacturing process of a wafer prober made of an aluminum nitride sintered body.

FIG. 11 is an explanatory diagram of a manufacturing process of a wafer prober made of an aluminum nitride sintered body.

[Explanation of symbols]

 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 electrode electrostatic layer 23, 73, 83a, 83b Chuck negative electrode electrostatic layer 41 Heating element 180 blind hole

 ──────────────────────────────────────────────────続 き Continued on front page F-term (reference) 4G001 BA01 BA05 BA08 BA09 BA36 BA78 BB09 BB36 BB60 BC13 BC42 BD01 BD03 BD16 BD23 BD31 BD36 BE01 5F031 CA02 DA13 EA01 HA17 HA37 MA28 MA32

Claims (5)

[Claims] To 1. A nitride aluminum in the analysis by laser Raman spectrum, the peak appeared in the vicinity of 1580 cm ^-1 and near 1355 cm ^-1, and the 15
Peak intensity ratio of the peak around 80 cm ^-1 and the peak near the ^{1355cm -1: I (1580) /} I (135
5) A carbon-containing aluminum nitride sintered body characterized by containing carbon exceeding 3.0. Wherein said 1355 cm ^-1 vicinity of the half width of the peak (FWHM) of the carbon-containing aluminum nitride sintered body according to claim 1 containing carbon is 20 cm ^-1 or more. 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. A sintering aid comprising at least one of an alkali metal oxide, an alkaline earth metal oxide and a rare earth oxide in said aluminum nitride. 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.