JP3040939B2 - Aluminum nitride and semiconductor manufacturing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to aluminum nitride and a semiconductor manufacturing apparatus using aluminum nitride as a base material.

[0002]

2. Description of the Related Art In semiconductor devices such as an etching device and a chemical vapor deposition device, a so-called stainless steel heater and a heater of an indirect heating system are generally used. However, when these heat sources are used, particles may be generated by the action of the halogen-based corrosive gas, and the heat efficiency is poor. In order to solve such a problem, the present applicant has disclosed a ceramic heater in which a wire made of a high melting point metal is embedded in a dense ceramic base material (Japanese Patent Application Laid-Open No. 3-261131). The wire is spirally wound inside the disc-shaped substrate, and terminals are connected to both ends of the wire. It has been found that such a ceramic heater has excellent characteristics especially for semiconductor production.

[0003] It is considered that nitride ceramics such as silicon nitride, aluminum nitride, and sialon are preferable as ceramics constituting the base of the ceramic heater. In some cases, a susceptor is installed on a ceramic heater, and a semiconductor wafer is installed on the susceptor to heat the semiconductor wafer. The present applicant has disclosed that aluminum nitride is preferable as the base material of such a ceramic heater or susceptor (Japanese Patent Application Laid-Open No. Hei 5-101873). Particularly, in a semiconductor manufacturing apparatus, a halogen-based corrosive gas such as ClF _{3 is} frequently used as an etching gas or a cleaning gas.
In terms of corrosion resistance to these halogen-based corrosive gases,
This is because it has been confirmed that aluminum nitride has extremely high corrosion resistance.

[0004]

The aluminum nitride sintered body itself is generally characterized by exhibiting white or grayish white. However, it is desired that the substrate used as the above-described heater or susceptor be black. This is because a black base material has a larger amount of radiant heat and a better heating characteristic than a white base material. In addition, in the case of such a type of product, when a white or gray base material is used, there is a disadvantage that color unevenness tends to occur on the surface of the product, and improvement has been demanded. Further, from the viewpoint of customer's preference, a base material having high blackness such as black, black-brown, or black-gray and having a low brightness is desired compared to a white or gray base material. Moreover, white or gray substrates have poor radiation characteristics.

In order to make the aluminum nitride sintered body black, a suitable metal element (blackening agent) is added to the raw material powder, and the resultant is fired to produce a black aluminum nitride sintered body. Is known (Japanese Patent Publication No. 5-64697). As this additive, tungsten, titanium oxide, nickel, palladium and the like are known.

However, when the metal element is added to the aluminum nitride sintered body as a blackening agent as described above, the content of metal impurities in the aluminum nitride sintered body naturally increases due to the effect of the additive. . In particular, in a semiconductor manufacturing process, Ia is contained in an aluminum nitride sintered body.
The presence of a group III element, a group IIa element, or a transition metal element can have a serious adverse effect on a semiconductor wafer or the device itself (for example, a defect of a semiconductor) Which can cause Therefore, it is required to reduce the brightness of the aluminum nitride sintered body without adding the above-described blackening agent.

An object of the present invention is to reduce the brightness of aluminum nitride and bring its color closer to black without adding a metal compound such as a blackening agent, particularly a heavy metal compound, to aluminum nitride. The object of the present invention is to
It is an object of the present invention to provide a semiconductor manufacturing apparatus having high radiation efficiency and high commercial value by using such a base material having a high degree of black.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a dense aluminum nitride having a content of metal elements other than aluminum of 100 ppm or less, and a laser Raman spectrum of aluminum nitride of 133 c.
The ratio I (133) / I (68) of the peak height I (133) of the peak at m ^{−1 and} the peak height I (680) of 680 cm ^−1.
0) is 0.4 or more, and the brightness defined in JIS Z 8721 is 4 or less.

Further, the present invention is characterized in that the above-mentioned aluminum nitride is used as a base material in a semiconductor manufacturing apparatus.

In the course of researching an aluminum nitride sintered body, the present inventor hardly contained any metal element such as a sintering aid or a blackening material other than aluminum.
It has succeeded in producing a black-grey or black-brown aluminum nitride sintered body with extremely low brightness, which exhibits a blackness of N4 or less as defined in IS Z 8721.

According to such aluminum nitride, JI
Since the brightness specified in SZ8721 is black with N4 or less, the amount of radiant heat is large and the heating characteristics are excellent. Therefore, it is suitable as a base material constituting a heating material such as a ceramic heater and a susceptor. In addition, since the content of metal elements other than aluminum can be extremely reduced, there is no possibility of causing semiconductor contamination or the like.
In particular, in the semiconductor manufacturing process, there is no possibility that the semiconductor wafer or the device itself will be adversely affected. Moreover, on the surface of the aluminum nitride of the present invention, color unevenness was hardly conspicuous, the appearance of the aluminum nitride sintered body was extremely good, and the blackness was high, so that the commercial value was significantly improved.

Here, the lightness will be described. The surface color of the object is represented by three attributes of color perception, hue, lightness, and saturation. The lightness is a scale indicating a visual attribute for determining whether the reflectance of the object surface is large or small. The display method of these three attribute scales is defined in "JIS Z 8721". The lightness V is based on an achromatic color, and the ideal black lightness is 0 and the ideal white lightness is 10. Between the ideal black and the ideal white, each color is divided into ten so that the perception of the brightness of the color becomes equal, and the symbols are indicated by symbols N0 to N10. When measuring the actual brightness of aluminum nitride, each standard color chart corresponding to N0 to N10 is compared with the surface color of aluminum nitride to determine the brightness of aluminum nitride. At this time, the brightness is determined to one decimal place in principle, and the value of one decimal place is set to 0 or 5.

The present inventor has studied the reason why aluminum nitride obtained as described below has a high blackening and low brightness. As a result, the brightness of aluminum nitride having the specific conditions described below was lowered, and the progress of blackening was found, and the present invention was completed.

First, when a black-brown or black-gray aluminum nitride having a lightness of 4 or less was analyzed by X-ray diffraction, the main crystal phase was AlN, but A
LON was generated.

On the other hand, when aluminum nitride powder having a purity of 99.9% by weight or more was sintered at 1950 ° C., a yellow-white sample was obtained. When the crystal structure of this sample was analyzed, a so-called 27R phase (Al ₂ O ₃ -7 (AlN) phase) was generated in addition to the AlN main crystal phase. The grain size of the AlN crystal phase was about _{2 to 4} μm, and a 27R phase (Al ₂ O ₃ -7AlN phase) was precipitated at the grain boundary. According to the known Al ₂ O ₃ —AlN phase diagram, the crystal phase formed after sintering changes around 1920 ° C.
Therefore, it is considered that the above-mentioned difference in the crystal phase is due to the difference in the sintering temperature.

When the above sample having a brightness of 4 or less was heat-treated at 1900 ° C. in a nitrogen atmosphere, a yellow-white portion was formed. In the yellowish white portion, except for the AlN main crystal phase, 2
There was almost no 7R phase, and the spherical ALON phase was dominant. The crystal phase of the sample obtained by the heat treatment of the low-brightness sample is different from that of the above-mentioned yellowish-white sample.

In addition, no difference was found in the lattice constant of AlN in any of the above-mentioned aluminum nitrides. In other words, no particular correlation was found between the lattice constant of the AlN crystal phase itself and the type of crystal phase other than the AlN crystal phase, and the color tone or brightness. Therefore, it is considered that the change in the color tone of aluminum nitride is not due to the type of crystal phase, but to the defect structure inside the AlN crystal phase and the defect structure at the grain boundary.

The present inventors have clarified the relationship between the physical properties of each of the above-described samples and the reason why the black color is developed, and explained the reason why the black color is developed in the highly pure aluminum nitride sample obtained as described below. For clarity, various spectra were examined as follows.

(Diffuse Reflection Spectra of Visible / Infrared Light) FIG. 1 (a) shows the visible / infrared light of an aluminum nitride sample having low brightness.
1 is a graph showing a diffuse reflection spectrum of infrared light, and FIG.
(B) is a graph showing a diffuse reflection spectrum of visible / infrared light in a yellowish white portion generated by heat-treating this sample at 1900 ° C. Because of the low light transmittance of the sample, the absorption characteristics of visible and infrared light were evaluated by the diffuse reflection method. In the diffuse reflection method, it can be determined that there is an absorption band near the wavelength where the reflection intensity is decreasing.

In the case of a sample having low brightness, a continuous absorption band was present in infrared light and visible light. In particular, the presence of continuous absorption of visible light causes blackening. In the yellow-white part, 300 nm to 500 nm
Absorption bands existed in the region and in the short wavelength band in the 200-300 nm region. Thus, yellow is generated by absorbing light on the short wavelength side. These visible / infrared absorption spectra are consistent with the color tone and lightness data of each sample. In particular, in a sample with low brightness, continuous absorption occurs over a wide range of wavelengths in the infrared and visible light regions, which means that a large number of bands are formed in the band gap. This is presumed to be a transient state before the crystal phase is stabilized with many lattice defects.

(Photoluminescence) In order to evaluate the band structure of aluminum nitride, photoluminescence was measured. FIG. 2A is a graph showing a photoluminescence spectrum of a sample having low brightness.
FIG. 2B is a graph showing the visible light region in the spectrum of FIG. 2A in an enlarged manner, and FIG. 3 is a photoluminescence spectrum of a yellowish white portion obtained by heat treatment of this sample.

In the yellow-white part, 990 in the infrared region
emission in the visible light region, 698 nm,
Broad peaks with broad emission widths were present at 530 nm and 486 nm, respectively. In the sample with low brightness, a large peak at 990 nm is detected as in the yellow-white portion. In addition, large light emission was not observed in the visible light region, and light emission was observed over the entire visible light region. Here, the reason why the luminescence intensity is weak is that the luminescence is absorbed again inside the sample because the brightness of the sample itself is low. As described above, it is characteristic that light emission is detected in a wide range of the visible light region, and this is because various types of band gaps are generated so that light of a wide range of wavelengths can be emitted. Means However, FIG.
(B) In FIG. 3, the peak indicated by the downward arrow is the noise of the spectral lamp when the measurement wavelength is switched from 540 nm to 570 nm.

(Raman spectrum) In order to know the structure of this defect structure that absorbs visible light over a wide wavelength range, a Raman spectrum was taken for each sample as described later. When a substance is irradiated with light having a frequency of f ₀ , light having a frequency of f ₀ ± f ₁ may be observed in the scattered light. Such a change in the frequency is caused by the transfer of energy between the photon incident on the substance and the substance. Therefore, by measuring the change f ₁ of the frequency, information on the lattice vibration and the electron level of the crystal in the substance can be obtained. The _one where f ₁ is in the range of about 4000 to ¹ cm −1 is called Raman scattering.

FIGS. 4 to 8 show Raman spectra measured for samples made of various aluminum nitride sintered bodies. From these Raman spectra, specifically, the lattice vibration mode of the AlN crystal can be evaluated, and from this evaluation, information on the defect inside the AlN crystal, the oxygen solid solution concentration, and the band structure in the band gap can be obtained. .

Al atoms and N atoms in the AlN crystal phase are 4
It has a coordinated wurtzite structure, and an sp ³ hybrid orbit is formed by an aluminum atom and three nitrogen atoms. As the symmetric species of the wurtzite structure, there are A ₁ species having c-axis symmetry, E ₁ species and E ₂ species having a-axis symmetry, and six optically active oscillations appear in the Raman spectrum. These peaks are identified as shown in Table 1. Table 1 shows each symmetric species and the Raman shift value (cm ⁻¹ ) of the peak in the Raman spectrum.

[0026]

[Table 1]

Each of these peaks can be observed in any of the samples. In addition, since there is no difference between the half widths of the peaks in each sample, it can be estimated that there is no clear difference in the amount of oxygen dissolved in the AlN crystal. here,
133～100Cm ^- peak within ^1, especially in the range 1
The peak at 33 cm ^{−1 is} a peak indicating that many electronic levels exist in the band gap of AlN.
In the yellow-white sample (FIGS. 4 and 8), the peak in this region, particularly the peak at 133 nm, is small, but in the black sample, the peak at 133 nm is relatively larger than the peak of the reference vibration. It can be seen that it appears strongly.

As described above, the peak at 80 to 150 nm, particularly 133 nm, which appears in the laser Raman spectrum corresponds to a specific electron level existing in the band gap of AlN. , A
The value normalized by dividing by the intensity of the 650-680 nm peak due to the normal vibration of the 1N crystal [I (13
3) / I (680)] is a significant physical characteristic value representing this band structure. Note that the Raman shift value of this peak may slightly deviate from 133 nm depending on experimental conditions and the like, but such a deviation is allowed within a significant range.

Specifically, by setting the above value to 0.40 or more, aluminum nitride having a lightness of N4.0 or less can be provided. By setting this value to 1.0 or more, the lightness becomes N3 or less. It has been found that aluminum nitride can be provided.

In the yellow-white portion formed by heat-treating the above-mentioned yellow-white sample or the black sample in a nitrogen atmosphere, oxygen forms a solid solution in the AlN crystal,
That is, it is considered that the N ^{3 +} site (site) in the AlN crystal was substituted with O ^{2 −} and Al ^{3 +} was lost. A color center is formed by the unpaired electrons trapped by the lattice defect, and the light on the short wavelength side of visible light is remarkably absorbed, and a yellow-white color is developed. Or, N ^{3 -} 2 one oxygen ions substituted changed to, O ₂ ^- color center consisting are presumed to be formed.

FIG. 9 shows the microstructure of the above-mentioned black aluminum nitride. As shown in FIG. 9, fine ALON crystals are present in the AlN crystal grains, and the grain boundaries where the crystals are in contact are in a dense state with no crystal grain boundaries and no gaps. FIG. 10 is an electron micrograph showing, on an enlarged scale, a grain boundary portion of a crystal made of AlN for a black aluminum nitride sample. No foreign phase is found at the AlN grain boundaries.

The low-brightness aluminum nitride having the above-mentioned Raman spectrum characteristics according to the present invention is:
It was manufactured by the following method. First, as a raw material composed of aluminum nitride powder, it is preferable to use a powder obtained by a reduction nitriding method. In the raw material composed of aluminum nitride powder, metal elements other than aluminum are 100
ppm or less. Here, “metal elements other than aluminum” refer to Ia to VIIa, VIII, and Ia in the periodic table.
b, a metal element belonging to IIb and a part of elements belonging to IIIb and IVb (such as Si, Ga, and Ge).

The above-mentioned high-purity aluminum nitride powder having a small metal content is prepared by a reduction nitriding method, and this aluminum nitride powder is formed by a uniaxial pressing method or a cold isostatic pressing method to produce a compact. I do. The compact is fired in a reducing atmosphere under conditions that do not contact the atmosphere. This firing method itself,
A hot press method or a hot isostatic press method can be adopted.

The firing pressure is 300 kg / cm ^2.
It was above. However, this pressure is preferably set to 0.5 ton / cm ² or less in view of the capability of the actual apparatus. At the same time, the holding temperature during firing is 1750 ° C. to 18 ° C.
The temperature is preferably set to 50 ° C.

The present inventors have studied this process in more detail. As a method for producing aluminum nitride powder, a reduction nitriding method and a direct nitriding method are known.
The chemical formulas used in each method are listed. Reduction nitriding: Al ₂ O ₃ + 3C + N ₂ → 2AlN + 3C
O Direct nitriding method: Al (C ₂ H ₅ ) ₃ + NH ₃ → AlN + 3
C ₂ H ₆ (vapor phase method) 2Al + N ₂ → 2AlN

As described above, the aluminum nitride crystal formed by the reduction nitriding method is manufactured by reducing and nitriding the γ-Al ₂ O ₃ phase with carbon. It is considered that carbon used as the reduction catalyst remains on the surface of the aluminum nitride crystal, and oxygen that has not been reduced and nitrided remains inside the aluminum nitride. Aluminum nitride is thermodynamically unstable in the atmosphere. Particularly, fine powder for surface active sintering easily reacts with moisture and oxygen in the atmosphere even at room temperature, and the amount of oxygen increases. Therefore, a surface oxide layer of an oxide or a hydroxide is coated to stabilize an aluminum nitride crystal that is active against moisture and oxygen. This oxidation treatment is used to remove carbon atoms remaining on the surface of the particles after the reduction treatment and to improve the purity.

For this reason, the important points in the quality of the aluminum nitride crystal are the oxide film present on the surface of the particles and the amount of oxygen dissolved in the aluminum nitride crystal during the reduction nitriding stage.

As described above, the particles obtained by such a reduction nitriding method are heated in a reducing atmosphere while applying the high pressure as described above. In this process, near the surface of the aluminum nitride particles, Al ₂ O ₃ and C
CO gas is generated by the reaction with (carbon).

The gaseous species (Al ₂ O ₂ , A
It is thought that a large number of electronic levels are generated in the AlN band gap by l ₂ O, Al) and oxygen vacancies, and a specific band structure that continuously absorbs visible light over a wide wavelength is formed. The reaction on the surface of the AlN powder at this time can be estimated as follows.

Al ₂ O ₃ + C → CO + Al ₂ O ₂ + V ₀ (oxygen vacancy) Al ₂ O ₃ + 2C → 2CO + Al ₂ O + 2V ₀ (oxygen vacancy) Al ₂ O ₃ + 3C → 3CO + Al ₂ + 3V ₀ (oxygen vacancy)

Here, the relative density of aluminum nitride is a value defined by the formula [relative density = bulk density / theoretical density], and its unit is “%”.

The aluminum nitride of the present invention has a large amount of radiant heat and excellent heating characteristics. In addition, since the color unevenness on the surface is hardly conspicuous and is blackish brown or blackish gray, the commercial value is high. Therefore, it can be particularly suitably used for various types of heating devices. In addition, the present aluminum nitride does not use a sintering aid or a blackening material that is a source of metal elements other than aluminum, and can reduce the content of metal atoms other than aluminum to 100 ppm or less. There is no danger. Therefore, it is optimal as a material for a high-purity process. In particular, in the semiconductor manufacturing process, there is no possibility that the semiconductor wafer or the device itself is seriously affected.

The semiconductor manufacturing apparatus using the aluminum nitride substrate of the present invention as a substrate includes a ceramic heater in which a resistance heating element is embedded in an aluminum nitride substrate, and a ceramic heater in which an electrostatic chuck electrode is embedded in the substrate. Examples include an active device such as an electric chuck, a heater with an electrostatic chuck in which a resistance heating element and an electrode for an electrostatic chuck are embedded in a base material, and a high-frequency generation electrode device in which a plasma generation electrode is embedded in a base material. be able to.

Furthermore, a susceptor for mounting a semiconductor wafer, a dummy wafer, a shadow ring, a tube for generating high-frequency plasma, a dome for generating high-frequency plasma, a high-frequency transmission window, an infrared transmission window, and a semiconductor wafer are supported. For manufacturing semiconductors, such as a lift pin and a shower plate for performing the operation.

In particular, the thermal conductivity of aluminum nitride should be at least 90 W / m · K for use as a base material for heating members such as ceramic heaters, heaters with electrostatic chucks, and susceptors for holding semiconductor wafers. Is preferred.

[0046]

EXAMPLES (Experiment A) An aluminum nitride sintered body was actually manufactured as follows. As the aluminum nitride raw material, a high-purity powder produced by a reduction nitriding method was used. In each powder, Si, Fe, Ca, Mg, K, Na, Cr, Mn,
The contents of Ni, Cu, Zn, W, B, and Y are each 1
It was less than 00 ppm, and no metals other than aluminum were detected.

Each of the raw material powders was uniaxially pressed to produce a disk-shaped compact. The formed body was set in a mold, and held in a nitrogen atmosphere at a predetermined pressure at a predetermined firing temperature for a predetermined time to produce a sintered body. These values are shown in Table 2. Further, the main crystal phase and other crystal phases of the sintered bodies of each example were measured by X-ray diffraction analysis. In addition, I (133) / I (680), relative density, color tone,
The lightness was measured.

However, the relative density of the sintered body was calculated from bulk density / theoretical density, and this bulk density was measured by the Archimedes method. The theoretical density of the sintered body is 3.26 g / cc because it does not contain a sintering agent having a large density. The color tone of the sintered body was measured visually, and the lightness of the sintered body was measured by the method described above. Table 2 shows the results. Experiments A1 and A5 correspond to claim 1 of the present invention.
And experiments A2, 3, 4, and 6 are within the scope of the present invention.

When taking a Raman spectrum, the laser wavelength was 514.5 nm, the monochromator was triple, the entrance slit was 1200 μm, and the sensitivity was 0.05 (nA / FS) × 100.

[0050]

[Table 2]

As can be seen from Table 2, the peak height I (133) at 133 cm ^-1 in Raman spectroscopy was 6
The ratio I (13) of the peak height I (680) at 80 cm ^-1
3) It can be confirmed that there is a clear correlation between / I (680) and the brightness and color tone of the sintered body. FIG. 9 shows an electron micrograph showing the ceramic structure of the sample of Experiment A2, and FIG. 10 shows an electron micrograph of the ceramic structure near the grain boundaries of the aluminum nitride particles. It was confirmed by electron micrographs that the samples of Experiments A3 and A4 also had substantially the same microstructure.

(Experiment B) The sample of Experiment A2 in Experiment A was heat-treated at 1900 ° C. for 2 hours in a nitrogen atmosphere to produce Sample B. The outer peripheral portion of Sample B turned yellow-white (lightness N8). When this part was cut out and a Raman spectrum was taken as described above, I (133)
/ I (680) was 0.10.

(Infrared spectroscopic spectrum) The visible / infrared reflection spectrum of the sample of Experiment A2 is shown in FIG. FIG. 1B shows a visible / infrared reflection spectrum of the sample of Experiment B. This description has been described above.

(Photoluminescence) The spectrum of the photoluminescence of the sample of Experiment A2 is shown in FIG.
FIG. 2A shows an enlarged view of the visible light region in FIG.
(B). FIG. 3 shows the photoluminescence spectrum of the sample of Experiment B. This description has been described above.

(Wafer Heating Experiment) Sample A2 of the Present Invention
210mm in diameter by the aluminum nitride sintered body of
A plate having a thickness of 10 mm was prepared, and this plate was placed in a vacuum chamber provided with a heating mechanism using an infrared lamp. An 8-inch diameter silicon wafer was placed on the plate, and a thermocouple for simultaneously measuring the temperatures of the plate and the silicon wafer was attached. As the infrared lamp, 20 infrared lamps having an infrared peak at a wavelength of about 1 μm of 500 W were mounted on an aluminum reflector, and the reflector and each lamp were installed outside the vacuum chamber.

The infrared light emitted from each infrared lamp is
A circular quartz window (250 mm in diameter, provided in a vacuum chamber, directly or after being reflected by a reflector)
(Thickness 5 mm) and reaches the aluminum nitride plate, which is heated.

In this heating apparatus, each infrared lamp is heated, the temperature of the plate is raised from room temperature to 700 ° C. in 11 minutes, and the plate is held at 700 ° C. for 1 hour. Thereafter, the infrared lamp is stopped and the plate is gradually cooled. Allow to cool. As a result, the power consumption of the infrared lamp was 8550 W at the maximum, and stable temperature control was possible. When the temperature of the silicon wafer was measured, the temperature of the silicon wafer was 615 ° C. when the temperature of the plate was maintained at 700 ° C.

(Heating Experiment by Comparative Example) Next, an aluminum nitride powder having a carbon content of 300 ppm obtained by a reduction nitriding method was used, and this powder was subjected to a cold isostatic pressing method under a pressure of 3 ton / cm ² . To produce a disk-shaped molded body,
It was fired at 940 ° C. for 2 hours to produce a white aluminum nitride sintered body having a density of 99.4%. Using this sintered body,
A heating experiment on a silicon wafer was performed in the same manner as described above.

As a result, the power consumption reached a maximum of 10 kW, and a delay of about 2 minutes was observed in the temperature rise time. Further, as described above, when the thermal cycle of the temperature rise and fall between room temperature and 700 ° C. was repeated, disconnection of the infrared lamp was easily caused. When the temperature of the silicon wafer was measured, the temperature of the plate was reduced to 70
When the temperature was maintained at 0 ° C., the temperature of the silicon wafer was 593 ° C., and it was found that the temperature of the silicon wafer was also lower than that of the above-described example of the present invention.

(Embedding Experiment of Electrodes and Resistance Heating Element) As in the case of the sample A2 of the present invention, the above-mentioned aluminum nitride powder was used, and a molybdenum diameter of 0.5
A coil (resistive heating wire) made of a 2 mm wire was buried, and a cylindrical electrode made of molybdenum having a diameter of 5 mm and a length of 10 mm was connected to the coil and buried. The embedded body was subjected to uniaxial pressure molding to obtain a disk-shaped molded body. At this time, the planar shape of the coil embedded in the molded body was a spiral shape.

The disk-shaped molded body was subjected to hot pressing at 1800 ° C. for 2 hours for 3 hours in the same manner as in Experiment A2.
The aluminum nitride sintered body was obtained by holding under a pressure of 00 kg / cm ² . The resistance heating element and the molybdenum electrode are embedded in the aluminum nitride sintered body. This molybdenum electrode can be used as an electrostatic chuck electrode and as a high frequency electrode.

[0062]

As described above, according to the present invention, the brightness of aluminum nitride can be reduced without adding a metal compound such as a sintering aid or a blackening agent, particularly a heavy metal compound, to aluminum nitride. , The color can be made closer to black. Further, by using such a base material having a high degree of black in a semiconductor manufacturing apparatus, a semiconductor manufacturing apparatus having high radiation efficiency and high commercial value can be provided.

[Brief description of the drawings]

1 (a) is a diffuse reflection spectrum of visible / infrared light of an aluminum nitride sample having low brightness, and FIG. 1 (b) is
It is a diffuse reflection spectrum of visible / infrared light of a yellowish-white part produced by heat-treating a sample with low brightness at 1900 ° C.

2 (a) is a photoluminescence spectrum of a sample having low brightness, and FIG. 2 (b) is a spectrum obtained by expanding a visible light region in the spectrum of FIG. 2 (a).

FIG. 3 is a photoluminescence spectrum of a yellowish white portion obtained by heat treatment of a sample having low brightness.

FIG. 4 is a Raman spectrum of a yellow-white sample.

FIG. 5 is a Raman spectrum of a black sample.

FIG. 6 is a Raman spectrum of a black sample.

FIG. 7 is a Raman spectrum of a black sample.

FIG. 8 is a Raman spectrum of a white sample.

FIG. 9 is an electron micrograph showing a ceramic structure of a sample having low brightness within the scope of the present invention.

FIG. 10 shows a low brightness sample within the scope of the present invention.
4 is an electron micrograph showing a ceramic structure near aluminum nitride particles.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-310571 (JP, A) JP-A-5-117038 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 35/581 C01B 21/072

Claims (3)

(57) [Claims] 1. A dense aluminum nitride, comprising aluminum
When the content of metal elements other than minium is 100 ppm or less
In the laser Raman spectroscopy spectrum of aluminum nitride, the peak height I (133 cm ^-1 ) (13
And 3) the ratio I (133 peak height of the ^{680cm -1 I (680)) /} I (680) Ri der 0.4 or more, J
Aluminum nitride , wherein the brightness specified in IS Z 8721 is 4 or less . 2. The aluminum nitride according to claim 1, comprising a main crystal phase made of AlN and a sub-crystal phase made of ALON. 3. An apparatus for manufacturing a semiconductor, wherein the aluminum nitride according to claim 1 or 2 is used as a base material.