JP3037883B2 - Aluminum nitride sintered body, method for manufacturing the same and apparatus for manufacturing semiconductor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum nitride sintered body and a method for producing the same, and also relates to a semiconductor manufacturing apparatus using such an aluminum nitride sintered body 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). In particular, in a semiconductor manufacturing apparatus, a halogen-based corrosive gas such as CF ₃ is frequently used as an etching gas and a cleaning gas. In terms of corrosion resistance to these halogen-based corrosive gases, aluminum nitride has a very high corrosion resistance. This is because it was confirmed that they had.

[0004]

However, 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, the use of white or gray substrates in these types of products has the disadvantage that color unevenness tends to appear on the product surface.
Improvement was required. Furthermore, in terms of customer preferences,
There is a demand for a base material having a higher blackness, such as black, black-brown, or black-gray, and a lower brightness than 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 an aluminum nitride sintered body to N4 or less without adding a metal compound such as a sintering aid or a blackening agent, particularly a heavy metal compound, to the aluminum nitride sintered body. That is.

[0008]

The present invention relates to an aluminum nitride sintered body, wherein the content of metal elements other than aluminum contained in the aluminum nitride sintered body is 100.
ppm or less, and the ratio of carbon atoms contained in the aluminum nitride sintered body is 500 ppm to 5000 ppm.
And the main crystal phase composed of aluminum nitride and ALON
(AlN) consisting of a sub-crystal phase consisting of
_x (Al ₂ OC) _1-x phase is not substantially contained, and a carbon peak is detected at an X-ray diffraction angle 2θ = 44 ° to 45 ° in an X-ray diffraction chart of the aluminum nitride sintered body. No peak corresponding to the c-axis plane is detected,
The brightness defined in JIS Z 8721 is not more than N4.

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

In the course of researching an aluminum nitride sintered body, the present inventor hardly contained a metal element such as a blackening agent other than aluminum, and more preferably, a lightness defined in JIS Z 8721. Has succeeded in producing a black-gray or black-brown aluminum nitride sintered body having extremely low brightness, which exhibits a black color of N4 or less.

According to such an aluminum nitride sintered body, in a preferred embodiment, since the brightness specified in JIS Z 8721 is black, which is 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 sintered body of the present invention, color unevenness is hardly conspicuous, the appearance of the aluminum nitride sintered body is extremely excellent, and the blackness is high, so that the commercial value is significantly improved. did.

More specifically, the present inventor has determined that a raw material powder consisting of only one type of aluminum nitride powder having a content of a metal element other than aluminum of 100 ppm or less and a carbon content of 500 ppm to 5000 ppm, Temperature between 1730 ° C and 1920 ° C and 80
By sintering at a pressure of over kg / cm ² ,
The brightness specified in IS Z 8721 is N4 or less;
We succeeded in producing black-brown and black-grey aluminum nitride substrates.

Further, the raw material powder may be as follows. (1) The content of metal elements other than aluminum is 100p
pm or less of aluminum nitride powder and an organic resin are wet-mixed to obtain a raw material powder, and the carbon content of the raw material powder is adjusted to 500 ppm to 5000 ppm. (2) A raw material powder is obtained by mixing a plurality of types of aluminum nitride powders having different carbon contents. In this case, the content of metal elements other than aluminum in the raw material powder is 100 p.
pm or less and the carbon content is 500 ppm to 5000 ppm.
ppm. In this case, three or more kinds of aluminum nitride powders can be mixed. But,
In a preferred example, a first aluminum nitride powder having a relatively low carbon content and a second aluminum nitride powder having a relatively high carbon content are mixed.

Thus, by sintering aluminum nitride powder containing a predetermined ratio of carbon under a high pressure and a temperature in a predetermined range, it is possible to stably produce an aluminum nitride sintered body having low brightness. succeeded in. Here, when the proportion of carbon is less than 500 ppm, the brightness of the sintered body increases, and when the proportion exceeds 5000 ppm,
Relative density of aluminum nitride sintered body is low, 92%
, And its color became gray.

When the firing temperature is lower than 1730 ° C., it was found that the compact was not sufficiently densified, the aluminum nitride sintered body became white, and the brightness increased to 7 or more. When the firing temperature of the powder exceeded 1920 ° C., a polytype phase was also generated, and the brightness of the aluminum nitride sintered body was increased. This firing temperature is 1750-19
In the range of 00 ° C., particularly the brightness of the aluminum nitride sintered body was reduced.

When the pressure during firing is less than 80 kg / cm ² , an AlN—Al ₂ CO crystal phase is generated,
It was found that the brightness of the aluminum nitride sintered body was increased due to the formation of a polytype phase other than the AlN crystal phase. This pressure is 150 kg / cm for a reason described later.
It is preferably at least ^2, more preferably at least 200 kg / cm ² . However, this pressure is preferably set to 0.5 ton / cm ² or less in view of the capability of the actual apparatus.

The aluminum nitride sintered body is JIS Z
It is more preferable that the brightness specified in 8721 is black with N3 or less.

The content of metal elements other than aluminum in the aluminum nitride powder is 100 ppm or less. Here, “metal elements other than aluminum” refers to Ia in the periodic table.
To VIIa, VIII, Ib, IIb and some of the elements belonging to IIIb, IVb (Si, G
a, Ge, etc.).

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 brightness of an actual aluminum nitride sintered body, each standard color chart corresponding to N0 to N10 is compared with the surface color of the aluminum nitride sintered body to determine the brightness of the aluminum nitride sintered body. I do. 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 relative density of the aluminum nitride sintered body is as follows:
It is a value defined by the formula [relative density = bulk density / theoretical density], and its unit is “%”.

Further, the inventor of the present invention has concluded that, even when the hot isostatic pressing method is used under the same conditions as described above, if the temperature and pressure are the same as the above-mentioned temperature and pressure, the brightness is not higher than N4. It was confirmed that a high-purity aluminum nitride sintered body could be manufactured.

The present inventors have studied the reason why the aluminum nitride sintered body obtained as described above has high blackening and low brightness. As a result,
The following facts have been found, and the present invention has been completed.

That is, in a sample whose brightness is 4 or less, which is black-brown or black-gray, the main crystal phase is AlN, but ALON is formed as a sub-crystal phase, and other crystal phases cannot be found. could not. As a result of X-ray diffraction analysis, it was found that a carbon peak clearly appeared, for example, as shown in FIG. this is,
This shows that a carbon phase is generated in addition to the above-mentioned main AlN crystal phase and ALON crystal phase.

From the X-ray diffraction analysis chart,
No peak corresponding to the c-axis plane was detected. this is,
There are only a few layers of a planar structure stacked in layers of carbon atoms, which means that the thickness of carbon is extremely thin. This carbon is
It is considered that it exists near the grain boundary of the AlN crystal layer.

When such a low-brightness sample is heat-treated in a nitrogen atmosphere, for example, at 1850 ° C., as can be seen from the X-ray diffraction chart shown in FIG. 2, the AlN crystal phase remains, but the peaks of the AlON phase and carbon are reduced. It has disappeared and is no longer detected. This is presumably because oxygen and carbon in the AlON phase employed the AlN crystal grains. For example,
An oxygen atom is substituted for the N site, which generates a color center that absorbs light of a short wavelength.

FIG. 3 shows the microstructure of the aluminum nitride sintered body of the present invention. As shown in FIG.
Fine AlON crystals are present in the crystal grains, almost no grain boundaries are seen between the crystal phases, and the boundaries where the crystals are in contact are dense and have no gaps. FIG. 4 is an electron micrograph showing, on an enlarged scale, a grain boundary portion of a crystal made of AlN for the aluminum nitride sintered body within the scope of the present invention. FIG.
4 is an electron micrograph showing an enlarged grain boundary portion of a crystal made of 1N. No foreign phase is found between the AlN crystals.

As a method for producing aluminum nitride powder, a reduction nitriding method and a direct nitriding method are known. In the present invention, a low-brightness aluminum nitride sintered body can be manufactured using any of the raw material powders prepared by any of the methods. The chemical formulas used in each method are listed below. 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

When sintering the aluminum nitride powder, a predetermined ratio of carbon is added and heated under a high pressure to sinter the powder. A exists near
Reduction of l ₂ O ₃ occurs and AlN is formed. In the course of this reduction proceeding according to the following formulas (1), (2), and (3), a band that continuously absorbs a wide range of visible light is formed on the surface of the AlN particles, and the brightness is reduced. It is considered something. However, at this point, the carbon phase must still remain near the grain boundaries. Firing temperature 195
When the temperature rises above 0 ° C., (Al ₂ O + C → Al ₂ OC
The formation of the Al ₂ OC phase progresses due to the reaction of (1), the carbon phase decreases, and the relatively unstable AlN particle surface band generated by the formulas (1), (2) and (3) decreases. Conceivable. Also, if the retention time is too long,
It is considered that a decrease in carbon occurs similarly.

(1) Al ₂ O ₃ + C → Al ₂ O ₂ + CO (2) Al ₂ O ₃ + 2C → Al ₂ O + 2CO (3) Al ₂ O ₃ + 3C → Al ₂ + 3CO

The aluminum nitride sintered body of the present invention is
A main crystal phase composed of N, a sub-crystal phase composed of ALON,
Consisting of carbon phase, (AlN) _x (Al ₂ OC) _1-x
It does not substantially contain a phase and has a brightness of N4 or less as defined in JIS Z 8721.

That is, when the aluminum nitride powder is sintered at a pressure of about 80 to 100 kg / cm ² , the brightness becomes 4 to 5
Gray aluminum nitride sintered body may be formed. According to the results of X-ray diffraction analysis and other spectrum analysis of this crystal phase, this matrix was basically provided with a main crystal phase composed of AlN, a sub-crystal phase composed of ALON, and a carbon phase. On the other hand, 150kg / c
When a pressure of m ² or more was employed, the brightness of the sintered body further decreased, and a sintered body of N 4 or less was obtained stably.

There was no difference in the basic matrix microstructure between the two. However, as shown in the electron micrographs of FIGS. 6 and 7,
It was found that the (AlN) _x (Al ₂ OC) _1-x phase was slightly formed in the gray product. Around this phase,
A minute gap is formed between the AlN crystal phase and the gap, light is scattered in the gap, and the scattered light causes an increase in brightness. Therefore, such (AlN) _x (Al ₂ O
C) By preventing the formation of the _1-x phase, the brightness of the aluminum nitride sintered body can be further reduced to 4 or less, and further to 3.5 or less.

As an organic resin to be added to the aluminum nitride powder, for example, there is a phenol resin.

The aluminum nitride powder and the organic resin are mixed by wet mixing using an organic solvent.

The aluminum nitride sintered body 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, since the present aluminum nitride sintered body does not use a sintering aid or a blackening agent as a supply source of a metal element except aluminum, and can reduce the content of metal atoms other than aluminum to 100 ppm or less. There is no risk of contamination. 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 sintered body of the present invention as a base material includes a ceramic heater having a resistance heating element embedded in an aluminum nitride base material, and an electrostatic chuck electrode embedded in the base material. Active devices such as a ceramic electrostatic chuck, a heater with an electrostatic chuck in which a resistance heating element and an electrode for an electrostatic chuck are embedded in a substrate, and a high-frequency generation electrode device in which a plasma generation electrode is embedded in a substrate. Can be exemplified.

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.

The thermal conductivity of the aluminum nitride sintered body is particularly 90 W / m · K or more when used as a base material of a heating member such as a ceramic heater, a heater with an electrostatic chuck, and a susceptor for holding a semiconductor wafer. Is preferred.

[0039]

EXAMPLES (Experiment A) Experiment A1 in Tables 1 and 2 was actually performed as follows.
To A12 were manufactured. As the aluminum nitride raw material, a high-purity powder produced by a reduction nitriding method or a direct nitriding method was used. In each powder, Si, Fe, Ca, Mg, K, Na, Cr, M
The content of each of n, Ni, Cu, Zn, W, B, and Y is 100 ppm or less.
Other than these were not detected. Tables 1 and 2 show the carbon content of each experimental example.

Each raw material powder was uniaxially pressed to produce a disc-shaped preform, which was hot-pressed in a sealed state. The firing temperature, the holding time at each firing temperature, and the pressure in this firing step were changed as shown in Tables 1 and 2. For the aluminum nitride sintered body of each example, the main crystal phase and other crystal phases of the sintered body were measured by X-ray diffraction analysis. The relative density of the sintered body was calculated from bulk density / theoretical density, and the 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.
It is. The amount of carbon in the sintered body was measured by elemental analysis. The color tone of the sintered body was measured visually, and the lightness was measured as described above.

[0041]

[Table 1]

[0042]

[Table 2]

In Experiment A1 outside the present invention, the amount of carbon was set to 150 ppm, the firing temperature was set to 1800 ° C.,
The pressure was 200 kg / cm ² . In the obtained sintered body, the crystal phase other than the AlN crystal phase was only AlON, and the carbon phase was not detected by X-ray diffraction analysis. This color was gray. Experiment A within the scope of the present invention
In No. 2, the amount of carbon was 500 ppm, the firing temperature was 1800 ° C., and the pressure was 100 kg / cm ² . In the obtained sintered body, an AlON crystal phase and a carbon phase were detected. The color tone of this sintered body was black gray, and the lightness was N3.5. In Experiment A3 outside the present invention, the amount of carbon was 750 ppm, the firing temperature was 1700 ° C., and the pressure was 200 kg / cm ² . No carbon phase was detected in the obtained sintered body. The color tone of this sintered body was white.

In Experiment A4 of the present invention, the amount of carbon was 750 ppm, the firing temperature was 1750 ° C., and the pressure was 150 kg / cm ² . In the obtained sintered body,
An AlON crystal phase and a carbon phase were detected. The color tone of this sintered body was black gray, and the brightness was N4. In experiment A5 within the present invention, the amount of carbon was 750 ppm, the firing temperature was 1850 ° C., and the pressure was 50 kg / cm.
^{And 2} . In the obtained sintered body, AlON crystal phase,
In addition to the carbon phase, an (AlN) _x (Al ₂ OC) _1-x phase was detected. For this reason, the color tone of the sintered body was gray, but as described above, it was confirmed that the blackening of the matrix was significantly advanced. Experiment A within the present invention
6 and A7 also gave good results.

In Experiment A8 outside the present invention, the amount of carbon was 750 ppm, the firing temperature was 1950 ° C., and the pressure was 150 kg / cm ² . In the obtained sintered body,
Except for the AlN crystal phase, it was polytype. The color tone of this sintered body was milky white, and the brightness was N8. In Experiments A9, A10, and A11 in the present invention, good results were obtained. In Experiment A12 within the present invention, the amount of carbon was 10,000 ppm, the firing temperature was 1800 ° C., and the pressure was 200 kg / cm ² . In the obtained sintered body, the carbon phase was generated, and the blackening of the matrix was significantly advanced. However, since the porosity increased, the brightness of the entire sintered body was N5.

FIG. 1 shows an X-ray diffraction chart of the sintered body of Experiment A6. Peaks indicating AlN, AlNO and a carbon phase are confirmed. FIG. 3 is a micrograph showing the ceramic structure of the sintered body of Experiment A6,
FIG. 4 shows the ceramic structure near the grain boundaries. Experiment A
2. Similar X-ray diffraction charts and crystal structures were confirmed for the sintered bodies of Experiment A4, Experiment A7, Experiment A9, Experiment A10, and Experiment A11.

FIG. 6 shows the ceramic structure of the sintered body of Experiment A5, and FIG. 7 is an enlarged view of FIG. In this tissue, the results of the X-ray diffraction analysis of the matrix portion and the results of the analysis of the absorption spectrum of visible light were the same as those in Experiment A6. However, a black (AlN) _x (Al ₂ OC) _1-x phase is present in this matrix,
There is a slight gap between the crystal grains and the AlN crystal phase, and light is scattered in the gap and glows white.
The structure of the matrix of the sintered body is basically that of the aluminum nitride sintered body of the present invention, and the blackening is relatively advanced. However, the brightness of the sintered body has increased to N5 due to the scattered light.

Next, an experiment was conducted in which the sintered body of Experiment A6 was heat-treated in a nitrogen atmosphere. This sintered body is 185
After heat treatment at 0 ° C. for 2 hours, only the outer peripheral portion of the sintered body turned yellowish white, and the color tone and brightness of the central portion did not change. From the result of X-ray diffraction analysis of the portion that turned yellowish white,
This main crystal phase was an AlN crystal phase, and the peaks of the AlON phase and carbon disappeared and were no longer detected. No change was observed in the relative density and the lattice constant ratio.

In the vicinity of the surface of the sintered body in experiment A6, oxygen in the nitrogen atmosphere, oxygen in the AlON phase, and carbon
It is considered that they dissolved in 1N crystal grains. It is considered that such a reaction progresses slowly inside the sintered body.

(Experiment B) As in Experiment A,
The aluminum nitride sintered bodies of Experiments B1 to B15 in Tables 3, 4, and 5 were manufactured. As the aluminum nitride raw material, a high-purity powder produced by a reduction nitriding method or a direct nitriding method was used. In each powder, Si, Fe, C
a, Mg, K, Na, Cr, Mn, Ni, Cu, Zn,
The contents of W, B, and Y were each 100 ppm or less, and no metals other than aluminum were detected.

In the experiment B1, the aluminum nitride powder (carbon amount 500 pp) obtained by the reduction nitriding method was used.
m) was used. In other experiments, relatively high carbon content additives were added to each carbon content aluminum nitride powder. As this additive,
In some examples, a resin was used, and in other examples, aluminum nitride powder having a relatively high carbon content was used. A phenol resin powder was used as the resin, and the amount of addition was indicated. As the above-mentioned aluminum nitride powder, a powder obtained by a reduction nitriding method was used, and the carbon content and the addition amount were indicated. Also, the total carbon content (ppm) of the raw material powder after mixing is indicated.

Each raw material powder was uniaxially pressed to produce a disk-shaped preform, which was hot-pressed in a sealed state. The firing temperature, the holding time at each firing temperature, and the pressure in this firing step were changed as shown in Tables 3, 4, and 5. For the aluminum nitride sintered body of each example, the main crystal phase and other crystal phases of the sintered body were measured by X-ray diffraction analysis. Also, the relative density of the sintered body,
The color tone and lightness were measured in the same manner as in Experiment A.

[0053]

[Table 3]

[0054]

[Table 4]

[0055]

[Table 5]

In Experiment B1 of the present invention, a black-gray aluminum nitride sintered body was obtained. Experiments B2 and B within the present invention
In each of 3, B4, B5, and B6, an aluminum nitride sintered body having a black-gray color tone was obtained. In Experiment B7 outside the present invention, since the firing temperature was as low as 1650 ° C., the densification of the sintered body did not proceed, and the color tone of the sintered body became white because no carbon phase was generated. Experiment B within the present invention
In 8 and B9, a black-gray sintered body was obtained. In Experiment B10 within the present invention, the pressure was 70 kg / cm ² , but in the obtained sintered body, a carbon phase was generated, and the blackening of the matrix was progressing. The brightness was rising. In the ceramic structure of this sintered body, the (AlN) _x (Al ₂ OC) _1-x phase appears black between the matrices, similarly to the sintered body of Experiment A5. There was a slight gap between the crystal phase and the gap, and light was scattered in the gap and glowed white.

In the experiment B11 outside the present invention, the firing temperature was too high, so that the sintered body was polytype except for the AlN crystal phase, and the color tone of the sintered body became milky white. In Experiments B12, B13, and B14 within the present invention, an aluminum nitride sintered body having a black-gray color tone was obtained. In Experiment B15 of the present invention, the total carbon content of the aluminum nitride raw material powder was 7,600 ppm, and an AlON crystal phase and a carbon phase were generated as crystal phases other than the AlN crystal phase. However, since the sintering of the sintered body did not proceed and the relative density remained at 88.0%, the brightness was N5.

(Wafer Heating Experiment) Experiment A6 of the Present Invention
A plate having a diameter of 210 mm and a thickness of 10 mm was prepared from the aluminum nitride sintered body manufactured by the above-mentioned method, and this plate was placed in a vacuum chamber equipped 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. This infrared lamp has a wavelength of 500 W
Twenty of those having an infrared peak around μm were attached to an aluminum reflector, and the reflector and each lamp were placed outside the vacuum chamber.

The infrared radiation 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 temperature is maintained 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 8600 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 611 ° C. when the temperature of the plate was maintained at 700 ° C.

Similar experiments were performed on the aluminum nitride sintered bodies of Experiments A2, A9, A10 and A11, and the same results as described above were obtained.

(Heating Experiment by Comparative Example) Next, aluminum nitride powder having a carbon content of 750 ppm obtained by the 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 900 ° 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 Experiment A6 of the present invention, aluminum nitride powder having a carbon content of 750 ppm produced by the reduction nitriding method was used, and a molybdenum diameter was included in the powder. 0.5mm
A coil (resistance heating wire) made of the above-mentioned wire was embedded, 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 embedded. 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.

An aluminum nitride sintered body was obtained by holding the disc-shaped compact by hot pressing at 1800 ° C. for 3 hours under a pressure of 200 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.

[0066]

As described above, according to the present invention, the brightness of an aluminum nitride sintered body can be improved without adding a metal compound such as a sintering aid or a blackening agent, particularly a heavy metal compound, to aluminum nitride. And make the color closer to black.

[Brief description of the drawings]

FIG. 1 is a chart showing a result of an X-ray diffraction analysis of an aluminum nitride sintered body according to an example of the present invention.

FIG. 2 is a chart showing a result of an X-ray diffraction analysis of an aluminum nitride sintered body according to a comparative example.

FIG. 3 is an electron micrograph showing a ceramic structure of an aluminum nitride sintered body according to an example of the present invention.

FIG. 4 is an electron micrograph showing a ceramic structure around a grain boundary of AlN crystal phase particles in an aluminum nitride sintered body according to an example of the present invention.

FIG. 5 is an electron micrograph showing a ceramic structure around a grain boundary of AlN crystal phase particles in an aluminum nitride sintered body according to a comparative example.

FIG. 6 is an electron micrograph showing a ceramic structure in a state where (AlN) _x (Al ₂ OC) _1-x phase particles are generated between a matrix composed of AlN crystal phase particles.

FIG. 7 shows the matrix of FIG. 6 and (AlN) _x (Al
₂ OC) showing an enlarged of _1-x phase particles is an electron microscope photograph of a ceramic tissue.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI H05B 3/02 C04B 35/58 104R 3/20 356 104U H01L 21/302 G (56) References JP-A-5-330809 (JP, A) JP-A-5-101187 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 35/581

Claims (5)

(57) [Claims] 1. An aluminum nitride sintered body, wherein the content of metal elements other than aluminum contained in the aluminum nitride sintered body is 100 ppm or less, and the carbon atoms contained in the aluminum nitride sintered body are Is 50
0 ppm to 5000 ppm, comprising a main crystal phase composed of aluminum nitride, a sub-crystal phase composed of ALON, and a carbon phase, containing substantially no (AlN) _x (Al ₂ OC) _1-x phase; In the X-ray diffraction chart of the sintered body, a peak of carbon is detected at an X-ray diffraction angle 2θ = 44 ° to 45 °, a peak corresponding to the c-axis plane of carbon is not detected, and the brightness specified in JIS Z 8721 is reduced. An aluminum nitride sintered body characterized by being N4 or less. 2. An apparatus for manufacturing a semiconductor, comprising using the aluminum nitride sintered body according to claim 1 as a base material. 3. The brightness specified in JIS Z 8721 is N
A method for producing an aluminum nitride sintered body that is 4 or less, wherein the content of metal elements other than aluminum is 100 ppm or less, and the carbon content is 500 ppm to 5000 ppm.
Is obtained by sintering a raw material powder consisting of only one kind of aluminum nitride powder at a temperature of 1730 ° C. or more and 1920 ° C. or less and a pressure of 80 kg / cm ² or more to obtain an aluminum nitride sintered body. And a method for producing an aluminum nitride sintered body. 4. The brightness defined in JIS Z 8721 is N
A method for producing an aluminum nitride sintered body having a content of metal elements other than aluminum of 100 ppm or less and an organic resin by wet mixing in an organic solvent to obtain a raw material powder. At this time, the carbon content of the raw material powder is adjusted to 500 ppm to 5000 ppm, and the raw material powder is sintered at a temperature of 1730 ° C. or more and 1920 ° C. or less and a pressure of 80 kg / cm ² or more, so that aluminum nitride is sintered. A method for producing an aluminum nitride sintered body, comprising obtaining a sintered body. 5. The brightness defined in JIS Z 8721 is N
A method for producing an aluminum nitride sintered body having a carbon content of 4 or less, wherein a raw material powder is obtained by mixing only a plurality of types of aluminum nitride powders having different carbon contents, wherein the carbon content in the raw material powder is 500 ppm To 5000 ppm, and the content of metal elements other than aluminum to 100 ppm or less.
730 ° C or higher and 1920 ° C or lower and 80 kg /
A method for producing an aluminum nitride sintered body, characterized in that an aluminum nitride sintered body is obtained by sintering at a pressure of ² cm ² or more.