JP2003226580A - Aluminum nitride-based ceramic and member for producing semiconductor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the volume resistivity of an aluminum nitride-based ceramic. <P>SOLUTION: The length of (a) axis and the length of (c) axis of the lattice constant of aluminum nitride are ≥3.1120 and ≤3.1200 Å and ≥4.9810 and ≤4.9900 Å, respectively, and the aluminum nitride-based ceramic has a volume resistivity at room temperature of ≥1×10<SP>14</SP>Ω cm. Or, the aluminum nitride- based ceramic has a volume resistivity at 500°C of ≥1×10<SP>8</SP>Ω cm and a volume resistivity at 700°C of ≥1×10<SP>7</SP>Ω cm. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum nitride ceramic having a high volume resistivity and a semiconductor manufacturing member using the same.

[0002]

2. Description of the Related Art Sintered aluminum nitride is used as a base material for various members for semiconductor manufacturing equipment because it has corrosion resistance against halogen gas. Further, the base material of the ceramic heater needs to have predetermined insulation and thermal conductivity in the operating temperature range. Since the aluminum nitride sintered body has insulating properties and high thermal conductivity, it is used as a base material for a ceramic heater for heating a silicon wafer. However, the volume resistivity of the dense aluminum nitride sintered body is
At room temperature, it is usually around 10 ¹³ Ω · cm, for example, 50
It becomes 10 ⁷ Ω · cm or less at 0 ° C. Therefore, for example, an aluminum nitride sintered body having a volume resistivity of 10 ⁸ Ω · cm or more at 500 ° C. is desired.

[0003] The applicant of the present invention discloses in Japanese Patent Laid-Open No. 2000-44345 to manufacture an aluminum nitride sintered body having high corrosion resistance and volume resistivity by adding a magnesium component to an aluminum nitride raw material powder. Was disclosed.

[0004]

However, magnesium is an alkaline earth metal and is not always desirable in the semiconductor manufacturing process. Further, it is difficult to cope with higher temperature of the treatment process. It is difficult to stably obtain aluminum nitride ceramics having a high volume resistivity in a system containing a small amount of alkali metal or alkaline earth metal. In particular, it is difficult to obtain the aluminum nitride ceramics having the high volume resistivity as described above at 400 ° C. or higher, for example, 500 ° C.

An object of the present invention is to increase the volume resistivity of aluminum nitride ceramics.

Another object of the present invention is to increase the volume resistivity of the aluminum nitride ceramics in the high temperature region and ensure the insulating property in the high temperature region.

[0007]

According to the present invention, the a-axis length of the lattice constant of aluminum nitride is 3.1120 angstroms or more and 3.1200 angstroms or less, and c
Axial length of 4.9810 angstroms or more, 4.990
The present invention relates to an aluminum nitride ceramics, which is 0 angstroms or less and has a volume resistivity at room temperature of 1 × 10 ¹⁴ Ω · cm or more.

Further, according to the present invention, the a-axis length of the lattice constant of aluminum nitride is 3.1120 angstroms or more,
3.1200 angstroms or less, c-axis length of 4.9810 angstroms or more and 4.9900 angstroms or less, and volume resistivity at 500 ° C. of 1
The present invention relates to an aluminum nitride ceramics, which is characterized by having a value of × 10 ⁸ Ω · cm or more.

Further, according to the present invention, the a-axis length of the lattice constant of aluminum nitride is 3.1120 angstroms or more,
3.1200 angstroms or less, c-axis length of 4.9810 angstroms or more and 4.9900 angstroms or less, and volume resistivity at 700 ° C. of 1
The present invention relates to an aluminum nitride ceramics characterized by having a resistance of × 10 ⁷ Ω · cm or more.

The present invention also relates to a member for semiconductor production, characterized in that at least a part of the aluminum nitride ceramics is formed.

The present inventor has further studied the conditions of the aluminum nitride ceramics which enable the increase of the volume resistivity. As a result, a relatively large amount of carbon atoms and oxygen atoms are dissolved inside the aluminum nitride particles,
The inventors have found that by increasing the lattice constant of aluminum nitride, the resistance value of the aluminum nitride crystal itself can be increased, and the volume resistivity of the aluminum nitride ceramics can be increased, and the present invention has been reached. That is, it was found that the volume resistivity of ceramics is increased by increasing the lattice constant of aluminum nitride particles to a predetermined critical value or more on both the a-axis and the c-axis. This indicates that the crystal lattice of aluminum nitride is expanded with the solid solution of oxygen atoms and carbon atoms in the particles.

The lattice constant is to be measured by using the strong X-ray diffractometer described in the embodiment.

From the viewpoint of increasing the thermal conductivity of aluminum nitride ceramics, the a-axis length of the lattice constant of aluminum nitride is preferably 3.1180 angstroms or less, or the c-axis length is 4.9860 angstroms or less. Is preferred.

From the viewpoint of further increasing the volume resistivity of the aluminum nitride ceramics, the ratio (c / a) of the lattice constant of aluminum nitride to the a-axis length (a) of the c-axis length (c) is 1. It is preferably less than or equal to 6000. The lower limit of c / a is not particularly limited, but it is preferably 1.5950 or more from the viewpoint of ease of production.

The upper limit of the lattice volume of aluminum nitride is 4
2.00 x 10^-24cm ^ThreeThe following is preferred
41.90 × 10^-24cm^ThreeThe following should be changed
Is preferred.

Further, the present inventor has found that the ratio (d) of the amount of dissolved oxygen (d% by weight) in the aluminum nitride particles to the carbon content (b% by weight) in the aluminum nitride ceramics.
It was found that the volume resistivity of this ceramic at room temperature and high temperature can be further increased by setting / b) to 0.25 or more and 2.0 or less. From the viewpoint of further improving the volume resistivity of ceramics at room temperature and high temperature, d / b is preferably 0.4 or more,
It is more preferable to set it to 0.5 or more. Alternatively, d /
b is preferably 1.8 or less, and more preferably 1.5 or less.

Further, the present inventor has found that the thermal conductivity of the aluminum nitride ceramics can be remarkably improved by setting the amount of dissolved oxygen in the aluminum nitride particles to 0.5% by weight or less. discovered. This makes it possible to improve the thermal conductivity of the aluminum nitride ceramics to 90 W / mK or more, and further 100 W / mK or more.

From the viewpoint of improving the thermal conductivity of the aluminum nitride ceramics, the amount of solid solution oxygen is preferably 0.4% by weight or less, and 0.3% by weight.
The following is more preferable.

In the present invention, the contents of alkali metals and alkaline earth metals, which easily cause pollution, are less than 0.1%.
It is preferably 5 wt% or less, and more preferably 0.1 wt% or less.

The aluminum nitride ceramics of the present invention, particularly the sintered body, contains 0.1 to 10% by weight of a rare earth element.
It is preferable to contain it. As a result, a higher volume resistivity can be obtained by sintering at a lower temperature than in the case where no rare earth element is added. From this viewpoint, the content of the rare earth element is preferably 0.2% by weight or more, and more preferably 8% by weight or less. The addition of rare earth elements also has the effect of increasing the thermal conductivity.

The rare earth elements referred to here are 17 elements of samarium, scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.

Preferably, the rare earth metal element is one or more elements selected from the group consisting of yttrium, lanthanum, cerium, neodymium, samarium, gadolinium, dysprosium, erbium and ytterbium.

From the viewpoint of providing a sintered body having high corrosion resistance, which is suitable for applications such as semiconductor applications in which impurities are highly disliked,
The content of impurity metal elements other than aluminum and rare earth elements is preferably 100 ppm or less, 50
It may be more preferable to set it to be ppm or less.

In the present invention, the method of increasing the a-axis length and the c-axis length of the AlN crystal lattice is not particularly limited.

In a preferred embodiment, carbon and oxygen are included in the AlN crystal lattice during the growth or sintering of the AlN crystal. In this process, the AlN crystal lattice is microscopically expanded.

For example, an appropriate amount of boron carbide can be added to the aluminum nitride raw material and sintered. During this sintering process, when aluminum nitride is sintered, boron carbide reacts with vapor phase nitrogen to form boron nitride at grain boundaries, and carbon diffuses into the aluminum nitride particles to form a solid solution. It is considered that the oxygen component present in the aluminum nitride raw material also forms a solid solution.

When boron nitride powder is added to aluminum nitride raw material powder and sintering is performed, an increase in volume resistivity due to solid solution of carbon atoms and oxygen atoms in the aluminum nitride particles is not observed. I can't.

Further, the present inventor tried to add carbon powder to the aluminum nitride raw material powder to diffuse carbon atoms into the aluminum nitride particles. However, in this case, the carbon atoms disappeared or remained in the grain boundary phase, the amount of solid solution in the aluminum nitride particles was small, and the aluminum nitride crystal lattice was not expanded. this is,
This seems to support the fact that highly active carbon atoms were generated and diffused into the aluminum nitride particles in association with the reaction process of boron carbide and nitrogen in the gas phase.

In Japanese Patent Laid-Open No. 5-178671, 0.5% by weight of boron carbide (B ₄
C) is added to the aluminum nitride powder and sintered at 1800 ° C., whereby a relative density of 9
A sintered body having a thermal conductivity of 8.9% and a thermal conductivity of 153 W / m · k is obtained. This boron carbide is added for the purpose of suppressing the crystal grain growth and improving the surface smoothness, and the relation with the volume resistivity of the sintered body is not described. According to the study of the present inventor, with the addition of such a small amount of boron carbide, the solid solution of carbon atoms and oxygen atoms in the aluminum nitride particles does not significantly change the lattice constant, and the volume resistivity is increased. Does not contribute.

The aluminum nitride ceramics in the present invention means ceramics mainly composed of a polycrystal of aluminum nitride particles. Therefore, the manufacturing method of the aluminum nitride ceramics is not limited, and may be a chemical vapor deposition method, a physical vapor deposition method, a metal organic chemical vapor deposition method, a vapor deposition method, or the like. Preferably,
Aluminum nitride ceramics are manufactured by a sintering method.

The content of aluminum in the aluminum nitride ceramics must be such that the aluminum nitride particles can exist as the main phase, preferably 35% by weight or more, more preferably 50% by weight or more. is there.

The content of the aluminum nitride component in the aluminum nitride ceramics is preferably 80% by weight or more, more preferably 90% by weight or more.

By increasing the content of boron atoms in the aluminum nitride ceramics to 0.5% by weight or more and the content of carbon atoms to 0.1% by weight or more, the above-mentioned increase in the resistance value of the aluminum nitride particles can be achieved. Can be promoted. From this viewpoint, the content of boron atoms is more preferably 0.8% by weight or more, or the content of carbon atoms is more preferably 0.3% by weight or more.

By setting the content of boron atoms to 10% by weight or less, the thermal conductivity of the aluminum nitride ceramics can be increased. From this viewpoint, the content of boron atoms is more preferably 5% by weight or less. Further, by setting the content of carbon atoms to be 2.5 wt% or less, the thermal conductivity of the aluminum nitride ceramics can be increased. From this point of view, the content of carbon atoms is more preferably 1.5% by weight or less.

In a preferred embodiment, the weight ratio of carbon atoms to boron atoms (C / B) is 0.1 or more,
It is set to 0.5 or less. As a result, the volume resistivity of the aluminum nitride ceramics is further increased.

In the present invention, the volume resistivity of the aluminum nitride ceramics at room temperature is 1 × 10 ¹⁴ Ω.
・ Can be more than cm. Furthermore, this is 5 × 10
¹⁴ Ω · cm or more, particularly 1 × 10
It can be ¹⁵ Ω · cm or more.

Further, in the present invention, the volume resistivity of the aluminum nitride ceramics at 500 ° C. is 1 × 10.
It can be ⁸ Ω · cm or more. Furthermore, this is 5
It can be set to x10 ⁸ Ω · cm or more.

Further, in the present invention, the volume resistivity of the aluminum nitride ceramics at 700 ° C. is 1 × 10.
It can be ⁷ Ω · cm or more. Furthermore, this is 5
It can be set to x 10 ⁷ Ω · cm or more.

In a preferred embodiment, the open porosity of the aluminum nitride ceramics is 5% or less, more preferably 0.1% or less.

In a preferred embodiment, the aluminum nitride ceramic of the present invention has a thermal conductivity of 30 W / m.
It is K or more. There is no particular upper limit to the thermal conductivity, but it is usually 1
It is 50 W / m · k or less.

In a preferred embodiment, the aluminum nitride ceramic has a grain boundary phase mainly composed of boron nitride. Other than boron nitride, the following crystal phase may be generated. (1) A complex oxide phase of a rare earth element and aluminum. Preferably, a composite oxide phase having a garnet crystal structure or a perovskite crystal structure. (2) Borides of rare earth elements.

The raw material of aluminum nitride is the direct nitriding method,
Various production methods such as a reduction nitriding method and a vapor phase synthesis method from alkylaluminum can be used.

Boron carbide can be added to the raw material powder of aluminum nitride. In addition, when a rare earth element is added, in addition to oxides of rare earth elements, compounds such as nitrates, sulfates, oxalates, and alkoxides that produce rare earth element oxides by heating (precursor of rare earth element oxide) Can be added. This precursor can be added in powder form.
Alternatively, a compound such as nitrate or sulfate can be dissolved in a solvent to obtain a solution, and this solution can be added to the raw material powder. Thus, when the precursor is dissolved in the solvent, the rare earth element can be highly dispersed between the aluminum nitride particles.

For forming the sintered body, known methods such as dry pressing, doctor blade method, extrusion, casting, tape forming method and the like can be applied.

In the preparing step, the aluminum nitride raw material powder is dispersed in the solvent, and the boron carbide and the rare earth element compound can be added thereto in the form of the above-mentioned oxide powder or solution. When performing the mixing, it is possible by simple stirring, but when it is necessary to crush the agglomerates in the raw material powder, a pot mill, a trommel,
A mixing mill such as an attrition mill can be used. When an additive soluble in the solvent for crushing is used as the additive, the time for performing the mixing and crushing step may be the minimum short time necessary for crushing the powder. Further, a binder component such as polyvinyl alcohol can be added.

A spray drying method is preferable for the step of drying the solvent for mixing. Further, it is preferable that the dry powder is passed through a sieve to adjust the particle size thereof after carrying out the vacuum drying method.

In the step of molding the powder, a die pressing method can be used for producing a disk-shaped molded body. The molding pressure is preferably 100 kgf / cm ² or more, but is not particularly limited as long as the mold can be held. It is also possible to fill the powder in a hot press die in a powder state.

The sintered body of the present invention is preferably subjected to hot press firing, and the body to be fired is preferably hot pressed and sintered under a pressure of 50 kgf / cm ² or more.

The sintering temperature is not limited, but preferably 1
700 to 2200 ° C., more preferably 1750
Or higher, or 2100 ° C. or lower, most preferably 1750 ° C.-2050 ° C.

In the temperature raising step during sintering, 1400 to
It is preferable to maintain the temperature at 1700 ° C., which improves the thermal conductivity of the ceramic.

The aluminum nitride ceramics of the present invention can be suitably used as various members in a semiconductor manufacturing apparatus such as a silicon wafer processing apparatus or a liquid crystal display manufacturing apparatus. The semiconductor manufacturing device means a device used in a wide range of semiconductor manufacturing processes in which metal contamination of semiconductors is a concern. This includes an etching device, a cleaning device, and an inspection device in addition to the film forming device.

Further, the aluminum nitride ceramics of the present invention can be used as a member for high temperature exposed to the maximum temperature of 400 ° C. or higher, and has a certain degree of insulating property even at high temperature.

The semiconductor manufacturing member is particularly preferably a corrosion resistant member such as a susceptor for semiconductor manufacturing equipment. Further, it is suitable for a metal-embedded product in which a metal member is embedded in this corrosion-resistant member. Examples of the corrosion resistant member include a susceptor, a ring, a dome, etc. installed in a semiconductor manufacturing apparatus. In the susceptor, a resistance heating element,
Electrostatic chuck electrodes, high frequency generating electrodes, etc. can be embedded.

Since the aluminum nitride ceramics of the present invention has a high volume resistivity at high temperatures as described above, it is particularly suitable for a ceramic heater used in a high temperature region. Such a ceramic heater can be suitably used, for example, at a temperature of 400 ° C. or higher, and even 1000
It can be suitably used up to the maximum temperature of ℃.

Further, the aluminum nitride ceramics of the present invention are 10 ⁷ to 10 ⁹ Ω · cm even at 700 ° C.
Since it has a volume resistivity of some extent, it is useful as a base material for an electrostatic chuck even in such a high temperature region. That is, in the electrostatic chuck using the Johnson-Rahbek force, the volume resistivity of the base material is 1 × 10 ⁸ Ω · cm or more, 1 × 10 ¹³ Ω ·, in order to obtain high attraction force and high responsiveness.
It is desirable to control it to be cm or less. In this respect, the aluminum nitride ceramics of the present invention is, for example, 300 to 8
In the temperature range of 00 ° C, especially 400 to 700 ° C,
Since it exhibits such a volume resistivity, it is suitable for use in a high temperature region. Further, since it has a high resistance at room temperature, it is also useful as a base material for an electrostatic chuck utilizing Coulomb force.

[0056]

EXAMPLES (Experiment A) (1) Preparation of AlN / B ₄ C / Y ₂ O ₃ Mixed Powder A commercially available reduced nitriding powder was used as the AlN powder. As the B ₄ C powder, a commercially available one having a high purity and an average particle size of 2 μm or less was used. As the Y ₂ O ₃ powder, a commercially available powder having a purity of 99.9% or more and an average particle diameter of 1 μm or less was used.

Each powder was weighed so that each weight ratio shown in Table 1 and Table 3 was obtained. However, the amount of aluminum nitride is 10
The amount of B ₄ C and Y ₂ O ₃ added is 0 parts by weight, and the addition amount is shown in parts by weight. Using isopropyl alcohol as a solvent, wet mixing was carried out for 4 hours using a nylon pot and boulders. After mixing, take out the slurry, and in a nitrogen atmosphere
And dried to prepare a raw material powder. Incidentally, "parts" in the formulation powder shows AlN, B 4 _C, the rate calculated ignoring the contents of impurities with Y ₂ O ₃ powder.

(2) Molding and firing The raw material powder obtained by (1) is uniaxially pressure-molded at a pressure of 200 kgf / cm ² to prepare a disk-shaped molded body having a diameter φ50 mm and a thickness of about 20 mm, which is then subjected to firing graphite. Stored in a mold.

A hot press is used for firing, and the press pressure is 200 kgf / cm ² . Firing temperature 1800-20
It was kept at 00 ° C for 4 hours and cooled. For some materials, 1500 ° C or 1700 ° C before heating to firing temperature
At the temperature of 20 hours, a keep was introduced. The atmosphere is
A vacuum was applied from room temperature to 1000 ° C., and 1.5 kgf / cm ² of nitrogen gas was introduced from 1000 ° C. to the firing temperature.

(3) Evaluation The obtained sintered body was processed and evaluated as follows. (Relative Density) (Bulk Density) × 100 / (Theoretical Density Calculated from Formulation Composition) The bulk density was measured by the Archimedes method using pure water. (Volume Resistivity) Measured from room temperature to about 400 ° C. in a vacuum atmosphere by a method according to JIS C2141. The shape of the test piece was φ50 × 1 mm, and each electrode was formed of silver so that the main electrode diameter was 20 mm, the guard electrode inner diameter was 30 mm, the guard electrode outer diameter was 40 mm, and the applied electrode diameter was 45 mm. The applied voltage was 500 V / mm, and the current at 1 minute after applying the voltage was read to calculate the volume resistivity. (Bending strength) The room temperature four-point bending strength according to JIS R1601 was measured. (Thermal conductivity) The thermal diffusivity was measured and calculated by the laser flash method. Physical properties of aluminum nitride for specific heat
Adopted 753 J / kg ・ K. (Lattice constant) Measured by the WPPD method using Al ₂ O ₃ having a known lattice constant as an internal standard. Measurement conditions are CuK α1 (single color by Ge incident monochromator), 50kV, 300mA
, 2 θ = 30-120 °: rotating anticathode type X-ray diffractometer “RINT” manufactured by Rigaku Denki Co., Ltd. (carbon amount: b wt%) Quantification was performed by a high frequency heating infrared absorption method. (Crystalline phase) It was identified by an X-ray diffractometer. The measurement conditions are
CuK α, 50 kV, 300 mA, 2 θ = 10 to 70 °: rotating anticathode type X-ray diffractometer “RINT” manufactured by Rigaku Denki (microstructure observation) EPMA was used to analyze the distribution state of each element. (Amount of oxygen in particles: d% by weight) The amount of oxygen in the entire sintered body was obtained by chemical analysis. The amount of Y was quantified by inductively coupled plasma (ICP) emission spectrum analysis. This Y amount is changed to Y ₂ O
_The amount of oxygen contained in the amount of Y ₂ O ₃ was calculated by converting the amount into ₃ amounts. And from the oxygen content (chemical analysis value) of the whole sintered body,
The amount of oxygen contained in the amount of Y ₂ O ₃ was subtracted to obtain a calculated value (a wt%) of the amount of oxygen in the particles. (D / b) The carbon content (b% by weight) of the sintered body was quantified by a high frequency heating infrared absorption method. Then, the above d is b
Divided by

[0061]

[Table 1]

[0062]

[Table 2]

[0063]

[Table 3]

[0064]

[Table 4]

The experimental results of each example will be examined below. (Example 1) Raw material powder _{composition, AlN / B 4 C / Y} 2 O
₃ = 100 / 3.4 / 2 (parts by weight). This powder is molded and heated at a heating rate of 1000 ° C./hour to 1500
After being kept on the way for 20 hours, it was baked at 2000 ° C. for 4 hours to obtain a dense body having a density of 3.19 g / cm ³ and an open porosity of 0.02%.

The volume resistance at room temperature (25 ° C.) is 3 × 10.
¹⁵ Ω · cm, volume resistivity at 500 ℃ 1 × 10
¹⁰ Ω · cm, volume resistivity at 700 ° C is 2 × 1
Was 0 ⁸ Ω · cm. However, "3 x 10 ¹⁵ " Ω ・
cm is expressed as “3E + 15” Ω · cm, and the same notation is adopted in other parts.

The strength of the sample of Example 1 is 325 MPa, which is high strength. The thermal conductivity was 58 W / m · k.
This is because a large number of different kinds of atoms were solid-dissolved in the AlN grains, resulting in low thermal conductivity. By X-ray diffraction measurement, Al as the constituent phase
N, BN and YB4 were identified.

B, C, O, N in the sintered body by EPMA,
The distribution of Y is shown in FIG. As a reference, the distribution of the sample of Comparative Example 5 is shown in FIG. The brighter part in the figure,
Shows a lot of each element (see the rightmost color scale). From FIG. 1, it can be seen that in Example 1, a large amount of C and O was present in the AlN grains. No remarkable solid solution of B component in AlN grains was observed.

Table 2 shows the AlN lattice constant of the sample of Example 1. Compared to the normal AlN material, the sample of Example 1
Both the a-axis and the c-axis are significantly expanded, which suggests that a heteroatom forms a solid solution in the AlN grains. From EPMA, it can be seen that the solid solution elements are C and O atoms. The expansion of the AlN crystal lattice reduces the concentration of electrically conductive carriers,
Alternatively, it is presumed that crystal defects caused by solid solution hindered carrier movement.

(Examples 2 to 8) In Example 2, the raw material powder composition is the same as in Example 1, but 150
Not kept at 0 ° C. In this case, the volume resistivity hardly changes, but the thermal conductivity slightly decreases. In Examples 3 and 4, the manufacturing conditions and the amount of yttria added are the same as in Example 2, but B ₄ C is reduced. Thus, even if the amount of B ₄ C added was reduced, a high resistance material was obtained and the thermal conductivity was high.

In Example 5, the manufacturing conditions and the amount of yttria added were the same as in Examples 2, 3, and 4, but B ₄
The amount of C added was increased. Also in this example, a high resistance material was obtained. However, even if the amount of B ₄ C added is increased, the effect of increasing the resistance does not change so much, and the thermal conductivity decreases.

In Example 6, manufacturing conditions and B4
The amount of C added was the same as in Example 2, and yttria was not added. In this way, a high resistance material can be obtained without adding a rare earth element. However, a calcination temperature of about 2000 ° C. is required for densification, which results in high manufacturing cost.

In Examples 7 and 8, the thermal conductivity was 92, 11
It was 4 W / mK, which was very large. In Examples 7 and 8,
The amount of oxygen in the particles is low and is 0.5% by weight or less.
On the other hand, in Examples 1 to 6, the amount of oxygen in the particles was relatively high, and a clear correlation was found between the amount of oxygen in the particles and the thermal conductivity.

In Examples 1 to 8, the a-axis length is 3.1120 angstroms or more and the c-axis length is 4.9810 angstroms or more. Also, a /
b was in the range of 0.25 to 2.0.

(Comparative Examples 1 to 5) Comparative Example 1 is an additive-free AlN sintered body. AlN lattice constant is JCPDS value (N
o. 25-1133), which is smaller than the samples of the examples and does not have high resistance.

In Comparative Example 2, the raw material powder composition is AlN / B.
₄ C / Y ₂ O ₃ = 100 / 0.6 / 2 (parts by weight). Although the amount of B ₄ C added was small and the AlN lattice constant changed somewhat with respect to the JCPDS value, the effect of increasing the resistance was small.

In Comparative Example 3, a commercially available high-purity BN powder was used instead of B ₄ C, and the characteristics of the sintered bodies were compared. The raw material powder composition is AlN / BN / Y ₂ O ₃ = 100 / 8.5 /
2 (parts by weight). The constituent phases other than AlN are BN phase and
It is a YAlO ₃ phase and is similar to the B ₄ C additive material. However, the resistance at 500 ° C. is as low as 2 × 10 ₆ Ω · cm, although the amount of BN added is very large at 8.5 parts by weight. Al
The change of N lattice constant with JCPDS value is small.

In Comparative Example 4, a commercially available high-purity C powder was used instead of B4 C, and the characteristics of the sintered bodies were compared. Raw material powder composition is AlN / C / Y ₂ O ₃ = 100 / 0.6 / 2
(Parts by weight). Resistance at 500 ℃ is 6 × 10 ⁶ Ω · c
m is low. The thermal conductivity is as high as 163 W / m · k, and the change in AlN lattice constant with respect to the JCPDS value is small. Therefore, it is considered that in the C-added material, solid solution of C in AlN grains is unlikely to occur.

Comparative Example 5 is a reference material for EPMA measurement and is a normal AlN material, Y ₂ O ₃ -added Al.
N was used. High thermal conductivity of 174 W / m · k, AlN
The change in lattice constant with JCPDS value is small. EPMA in Figure 2
From the image, there is less solid solution of C and O in the AlN grains.

(Experiment B) An aluminum nitride sintered body was produced in the same manner as in Experiment A. However, in Experiment A, after the mixed powder was dried at 110 ° C. in a nitrogen atmosphere to prepare a raw material powder, the raw material powder was heat-treated at 450 ° C. for 20 hours to be calcined, and the calcined product was crushed to be calcined. A powder was obtained. This calcined powder was molded and fired in the same manner as in Experiment A. The raw material powder composition and firing conditions were changed as shown in Table 5. The measurement results of the obtained sintered body are shown in Table 5 and Table 6.

[0081]

[Table 5]

[0082]

[Table 6]

As can be seen from these results, by controlling the a-axis length and the c-axis length of the aluminum nitride crystal lattice according to the present invention, a high volume resistivity can be obtained at room temperature, 500 ° C. and 700 ° C.

(Experiment C) As a comparative example, as in Experiment A,
Then, a sintered body was manufactured. However, the raw material powder is AlN powder
Only B_FourNeither C powder nor yttria powder was added
It was The maximum temperature during firing is 1900 ° C.
Was held for 4 hours. As a result, the following measurement results
Got     Volume resistivity at room temperature 5.0 × 10¹²Ω · cm Volume resistivity at 500 ° C 2.0 × 10⁵Ω · cm Bending strength 400 MPa Thermal conductivity 96W / m ・ K a-axis length 3.1117 angstrom c-axis length 4.9783 Angstrom Lattice volume 41.743 × 10^-24cm^Three c / a

[0085]

As described above, according to the present invention, the volume resistivity of aluminum nitride ceramics can be increased.

[Brief description of drawings]

FIG. 1 B, C, O in the sample of Example 1 by EPMA
The distribution of N and Y is shown.

FIG. 2 shows B, C, O in the sample of Comparative Example 5 by EPMA.
The distribution of N and Y is shown.

Continued front page    F term (reference) 3K034 AA02 BA06 BA14 JA01                 3K092 PP20 RF11 RF27 VV06 VV19                 4G001 BA09 BA23 BA36 BB33 BB36                       BB42 BC51 BC52 BD23 BD38                       BE01

Claims (12)

[Claims] 1. An aluminum nitride having a lattice constant a-axis length of 3.1120 angstroms or more and 3.1200 angstroms or less and c-axis length of 4.9810 angstroms or more and 4.9900 angstroms or less at room temperature. Aluminum nitride ceramics having a volume resistivity of 1 × 10 ¹⁴ Ω · cm or more. 2. The a-axis length of the lattice constant of aluminum nitride is 3.1120 Å or more and 3.1200 Å or less, and the c-axis length is 4.9810 Å or more and 4.9900 Å or less at 500 ° C. Has a volume resistivity of 1 × 10 ⁸ Ω · cm or more. Aluminum nitride ceramics. 3. The lattice constant a-axis length of aluminum nitride is 3.1120 angstroms or more and 3.1200 angstroms or less, and c-axis length is 4.9810 angstroms or more and 4.9900 angstroms or less at 700 ° C. Has a volume resistivity of 1 × 10 ⁷ Ω · cm or more. Aluminum nitride ceramics. 4. The ratio (c / a) of the lattice constant of aluminum nitride to the a-axis length (a) of the c-axis length (c) is 1.6.
000 or less, The aluminum nitride ceramics according to any one of claims 1 to 3, which is characterized by being below. 5. The lattice volume of aluminum nitride is 41.77.
It is -42.07 * 10 ^<-2 >^{< 4} > cm ^{< 3} >, The aluminum nitride ceramics of any one of Claims 1-4 characterized by the above-mentioned. 6. The ratio (d / b) of the solid solution oxygen content (d weight%) in the aluminum nitride particles to the carbon content (b weight%) of the aluminum nitride ceramics is 0.25 or more and 2.0 or less. 1 to 5, characterized in that
The aluminum nitride ceramics according to claim 1. 7. The content of the alkali metal and the alkaline earth metal is 1 wt% or less, wherein
Aluminum nitride ceramics according to claim 1. 8. The aluminum nitride ceramics according to claim 1, which is used at a temperature of 400 ° C. or higher. 9. A sintered body, which is characterized in that
9. The aluminum nitride ceramics according to claim 8. 10. A member for semiconductor production, characterized in that at least a part thereof is made of the aluminum nitride ceramics according to any one of claims 1 to 9. 11. A semiconductor manufacturing member according to claim 10, comprising a base material made of the aluminum nitride ceramics and a metal member embedded in the base material. 12. The member for semiconductor production according to claim 10, which is a ceramic heater.