JP2883207B2 - Aluminum nitride sintered body and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an aluminum nitride sintered body and a method for producing the same.

BACKGROUND OF THE INVENTION Conventionally, in a semiconductor device such as an etching device and a chemical vapor deposition device, a so-called stainless steel heater or a heater of an indirect heating method has been 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 inventors have proposed a ceramic heater in which a wire made of a high melting point metal is embedded in a dense ceramic base material. This wire is spirally wound inside the disc-shaped substrate,
In addition, terminals are connected to both ends of this wire. It has been found that such a ceramic heater has excellent characteristics especially for semiconductor production.

It is considered that as a ceramic constituting the base of the ceramic heater, a nitride ceramic such as silicon nitride, aluminum nitride, and sialon is preferable.
In addition, a susceptor is installed on the ceramic heater,
There is a case where a semiconductor wafer is placed on the susceptor and the semiconductor wafer is heated.

As a base material of such a ceramic heater or susceptor, according to the study of the present inventors, aluminum nitride is preferable. Because, especially in semiconductor manufacturing equipment,
As an etching gas or a cleaning gas, but intensive halogen-based corrosive gas such as CF _3, in terms of corrosion resistance to these halogen-based corrosive gas, confirmed that the aluminum nitride has an extremely high degree of corrosion resistance Because it was done.

On the other hand, the substrate used as such a heater or susceptor is desired to 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.

However, the aluminum nitride sintered body itself generally has a white or grayish white color, and thus has poor radiation characteristics. Therefore, in order to make the aluminum nitride sintered body black,
A suitable metal element is added to the raw material powder, and this is fired to produce a black aluminum nitride sintered body (see 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 in this way, the content of impurities in the aluminum nitride sintered body increases due to the effect of the additive. In particular, in the semiconductor manufacturing process, if a group Ia element, a group IIa element, and a transition metal element are present in the aluminum nitride sintered body, even if the abundance is very small, the semiconductor wafer or the device itself may be used. Can have serious adverse effects. For example, it may cause a defect of a semiconductor.

DISCLOSURE OF THE INVENTION The present invention is characterized in that the content of each of the metal elements excluding aluminum is 100 ppm or less, and the brightness specified in JIS Z 8721 is black, which is N4 or less. It concerns the body.

Further, the present invention provides a method for producing an aluminum nitride sintered body, characterized in that the aluminum nitride powder obtained by the reduction nitriding method is sintered at a temperature of 1800 ° C. or more and a pressure of 120 kg / cm ² or more. It is related.

Further, the present invention, when sintering aluminum nitride powder having a content of metal elements other than aluminum is 100 ppm or less to obtain a sintered body, the relative density of the sintered body is 99.3% or more, The present invention relates to a method for producing an aluminum nitride sintered body, characterized in that the average particle diameter of crystal grains constituting the sintered body is 4.0 μm or less and 0.6 μm or more.

The present inventor, in the course of researching aluminum nitride sintered body, hardly contains metal elements such as sintering aids other than aluminum, and the brightness specified in JIS Z 8721 is N4 or less black The present invention succeeded in providing a black-gray or black-brown aluminum nitride sintered body having extremely low brightness, which exhibits the following characteristics.

According to such an aluminum nitride sintered body, JIS Z 87
Since the brightness specified in 21 is black with N4 or less, the amount of radiant heat is large and the heating characteristics are excellent. Therefore, it is most suitable as a base material constituting a heating material such as a ceramic heater and a susceptor. In addition, since the content of each of the metal elements except aluminum is 100 ppm or less, there is no possibility of causing contamination. In particular, in the semiconductor manufacturing process, there is no possibility that the semiconductor wafer or the device itself will be adversely affected.

Moreover, in the surface of the aluminum nitride sintered body, color unevenness inevitably occurs. However, on the surface of the aluminum nitride sintered body of the present invention, the color unevenness is hardly conspicuous, It was found that the appearance of the aggregate was extremely good.

It is further preferable that the aluminum nitride sintered body has a black color having a brightness defined by JIS Z 8721 of N3 or less.

Here, "metal elements other than aluminum" refers to a part (Al, Si, Ga, Ge, etc.) of Ia to VIIa, VIII, Ib, IIb and IIIb, IVb of the periodic table.

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 method of displaying these three attribute scales is defined in JIS Z 8721. The lightness V is based on an achromatic color. The ideal lightness of black is set to 0, the lightness of ideal white is set to 10, and between ideal black and ideal white,
Divide into 10 so that the perception of the brightness of the color is equal,
It is indicated by the symbols N0 to N10. When measuring the lightness of an actual sintered body, each standard color chart corresponding to N0 to N10 is compared with the surface color of the sintered body to determine the lightness of the sintered body. 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.

More specifically, the present inventors succeeded in obtaining the aluminum nitride sintered body by hot-press sintering the aluminum nitride powder obtained by the reduction nitriding method at a temperature of 1800 ° C. or higher. .

In addition, the present inventor has examined the conditions of the hot press sintering in detail, and has found that a sintered body using a high-purity aluminum nitride powder as a raw material, an aluminum nitride sintered body having a brightness of N4 or less, has never been produced. To do so, it was found that the pressure during hot pressing had to be 120 kg / cm ² or more. That is, under these conditions, a high-purity aluminum nitride sintered body having a relative density of 99.3% or more and a lightness of N4 or less was successfully manufactured.

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

As a method for producing a raw material powder of an aluminum nitride sintered body, a reduction nitriding method and a direct nitriding method are known.
The chemical formulas used in each method are listed below.

Reduction nitridation method: Al ₂ O ₃ + 3C + N ₂ → 2AlN + 3CO Direct nitridation method: Al (C ₂ H ₅ ) ₃ + NH ₃ → AlN + 3C ₂ H ₆ (vapor phase method) 2Al + N ₂ → 2AlN Examination of the structure of the following aluminum nitride sintered body revealed that the size of the crystal grains constituting the aluminum nitride sintered body was important. That is, it has been found that when the average particle size exceeds 4.0 μm, the brightness of the aluminum nitride sintered body increases. In particular, it has been found that in a dense sintered body in which the relative density of the aluminum nitride sintered body is 99.3% or more, when the above average particle size exceeds 4.0 μm, the lightness exceeds 4.

Further, from this viewpoint, the average particle size of the crystal particles constituting the aluminum nitride sintered body is set to 3.0 μm or less,
More preferred.

The temperature at which the aluminum nitride powder obtained by the reduction nitriding method is sintered is set to 1800 ° C. or higher. As in the present invention, in the sintered body, metal elements other than aluminum
Under the condition of 100 ppm or less, an effective amount of a sintering aid composed of a metal oxide such as Y ₂ O ₃ cannot be used. Therefore, since the densification of the sintered body does not easily progress, if the above sintering temperature is lower than 1800 ° C., increasing the relative density of the sintered body as described above is performed by pressing such as hot pressing. It was difficult under the conditions.

Further, the firing temperature is preferably set to 2000 ° C. or lower. When the sintering temperature exceeds 2000 ° C., the relative density of the sintered body tends to decrease due to oversintering, and the growth of particles in the sintered body increases, and the average particle size increases. Because it comes.

Further, setting the firing temperature to 1950 ° C. or lower is preferable from the viewpoint of production because the formed body can be easily heated with the ability of a normal sintering apparatus. On the other hand, when the firing temperature is 1850 ° C. or higher, the relative density of the aluminum nitride sintered body can be 99.7% or more even under pressure conditions such as hot pressing, and the brightness of the aluminum nitride sintered body can be increased. N3 or less.

The holding time when sintering the aluminum nitride powder obtained by the reduction nitriding method is preferably at least 2 hours in order to increase the blackness of the sintered body. However, if the sintering is performed for more than 5 hours within the above-described range of the sintering temperature and pressure, the particles tend to grow excessively inside the sintered body. Is preferably 5 hours or less.

Furthermore, the present inventor has found that the relative density of the aluminum nitride powder produced by the reduction nitriding method is 99.3% or more under the same temperature and pressure conditions as those described above even when the hot isostatic pressing method is used. It was confirmed that a high-purity aluminum nitride sintered body having a brightness of N4 or less can be manufactured.

Further, they have found that when aluminum nitride powder is sintered in a non-oxidizing atmosphere, an aluminum nitride sintered body having a high degree of blackness can be easily produced. As the non-oxidizing atmosphere, an inert gas atmosphere such as nitrogen is particularly preferable. Furthermore,
After preforming the aluminum nitride powder, it is preferable to perform hot press sintering or hot isostatic press sintering of the preformed body.

The aluminum nitride powder obtained by the reduction nitriding method is
The pressure at the time of sintering, from the viewpoint of the capacity of the actual equipment,
It is preferable to be 0.5 ton / cm ² or less.

Also, under the above-mentioned temperature conditions and pressure conditions,
When the high-purity aluminum nitride powder was a powder obtained by a direct nitriding method, only a sintered body having a relative density of about 97% and a high brightness was obtained. However, this is considered to be due to the fact that the raw material powder obtained by the direct nitriding method does not easily sinter without a sintering aid.

Also, in this case, when aluminum nitride powder to which Y ₂ O ₃ as a sintering aid is added is used, even if the relative density of the sintered body is 99.4% or more, only the sintered body having a brightness of 5.5 or more can be obtained. Could not be manufactured. This was the same whether the raw material powder was obtained by the reduction nitriding method or the direct nitriding method. That is, it was a necessary condition to use a high-purity aluminum nitride powder in which the content of metal elements other than aluminum was 100 ppm or less.

The present inventor further studied, when sintering aluminum nitride powder having a content of metal elements other than aluminum of 100 ppm or less, relative density of the sintered body
It has been confirmed that an aluminum nitride sintered body having a lightness of N4 or less can be produced by sintering so that the average particle diameter becomes 99.3% or more and the average particle diameter becomes 4.0 μm or less. Furthermore, by sintering the sintered body so that the relative density of the sintered body was 99.7% or more, an aluminum nitride sintered body having a brightness of N3 or less could be manufactured.

In this case, similar results were obtained even when a high-purity aluminum nitride powder produced by a direct nitriding method and having a content of metal elements other than aluminum of 100 ppm or less was used.

The average particle diameter of the particles constituting the aluminum nitride sintered body is preferably 0.6 μm or more, which is 0.6 μm
If it is less than this, sintering is insufficient.

Further, the average particle diameter of the particles constituting the aluminum nitride sintered body is preferably 1.0 μm or more and 2.0 μm or less, whereby a sintered body having a brightness of 3 or less could be obtained.

The inventor has set the relative density of the aluminum nitride sintered body to:
By examining the reason why the color of the sintered body suddenly turns black by making it extremely high at 99.3% or more, the reason is that if there is a certain amount of pores in the sintered body, It is considered that the sintered body looks whitish due to irregular reflection at the interface between the pores and the particles. Further, when the average particle size of the particles constituting the sintered body is reduced, the number of grain boundaries through which visible light passes increases. Needless to say, pores hardly exist due to the relative density of the sintered body being high, and the amount of metal elements other than aluminum is also small, so the size of each grain boundary is also small, but these grain boundaries have When there is a defect having an energy level that absorbs visible light (for example, oxygen defect or the like), the average particle size of the particle decreases, and the number of grain boundaries increases, the brightness decreases. It is thought to come.

According to the aluminum nitride sintered body of the present invention, the amount of radiant heat is large and the heating characteristics are excellent. Therefore, as a base material for heating members such as ceramic heaters and susceptors,
It is suitable. Since the contents of all metal elements except aluminum are 100 ppm or less, there is little risk of contamination. Therefore, metal elements other than aluminum (in particular, Ia
It is most suitable as a material for high-purity processes in which the effects of group elements, group IIa elements and transition metal elements) should be suppressed.
In particular, in the semiconductor manufacturing process, there is no possibility that the semiconductor wafer or the device itself is seriously affected. In the semiconductor manufacturing process, it has high durability against exposure to a halogen-based corrosive gas.

In particular, the thermal conductivity of the aluminum nitride sintered body is preferably 90 W / m · K or more for use as a heating member such as a ceramic heater or a susceptor.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the relationship between lightness N and relative density of a high-purity aluminum nitride sintered body.

BEST MODE FOR CARRYING OUT THE INVENTION (Comparative Examples 1 to 3 and Example 1) The inventor actually manufactured an aluminum nitride sintered body. As a raw material, an aluminum nitride powder produced by the above-described direct nitriding method was used.

In Comparative Examples 1 and 2 shown in Table 1, yttria was 5
In Comparative Example 3 and Example 1, a high-purity aluminum nitride powder containing no yttria was used.

In Comparative Examples 1 and 3 shown in Table 1, each raw material powder was uniaxially pressed to produce a preform, which was hot-pressed. 200kg / cm for hot press firing
A pressure of ² was applied and firing was performed at 1900 ° C. for 2 hours. In Example 1, when hot-pressing the preform,
A pressure of 400 kgf / cm ² was applied and firing was performed at 1950 ° C. for 2 hours. In Comparative Example 2, the preformed body was cold isostatically pressed at a pressure of 7 tf / cm ² to obtain a formed body, and the formed body was housed in a sagger made of boron nitride and constantly kept at 1900 ° C. for 3 hours. Pressure firing was performed.

Then, for the aluminum nitride sintered body of each example, the color tone, lightness, bulk density, relative density, average particle size, number of grain boundaries, thermal conductivity, infrared transmittance, content of impurity elements, main component of the sintered body Was measured.

However, the brightness of the sintered body was measured as described above. The bulk density of the sintered body was measured by the Archimedes method. The theoretical density of the sintered body is determined by the raw material powder. That is,
In Comparative Examples 1 and 2 in which the added amount of Y ₂ O ₃ was 5% by weight, the theoretical density of the sintered body was 3.36 g / cc, and Comparative Example in which the added amount of Y ₂ O ₃ was 0% by weight. 3. In Example 1, the theoretical density of the sintered body is 3.26 g / cc.

The average particle size and the number of grain boundaries of the particles constituting the sintered body are AS
Performed according to TM E112-85. That is, the sintered body of each example was processed to prepare a rectangular parallelepiped sample having a length of 4 mm, a width of 3 mm, and a length of 40 mm. Was. The fracture surface where the grain boundary was broken was observed with a scanning electron microscope, and the scanning electron micrograph was image-analyzed to determine the average grain size and the number of grain boundaries. That is, 30
A region of × 30 μm was defined as one observation visual field, and 10 or more observation visual fields were measured, and the average value of each average particle size in each observation visual field was determined. Further, the number of grain boundaries existing on a straight line having a length of 30 μm was measured and displayed as the number of grain boundaries.

When measuring the infrared transmittance, the thickness of the measurement sample was 300 μm, the wavelength was 5 to 6 μm, and an IR-810 infrared spectrophotometer was used. This is based on the TFD electrical direct ratio method, and uses a double beam filter and a grating spectroscope as an optical system. Table 1 shows the measurement results.

As can be seen from Table 1, when the aluminum nitride powder obtained by the direct nitriding method is used, the color tone of the sintered body is gray, light brown, white, and the brightness is high. Therefore, the radiation characteristics are inferior. In particular, in Comparative Example 1, 5% by weight of yttria was used.
The powder contained is subjected to hot press sintering at 200 kgf / cm ² and 1900 ° C., but the relative density has increased to 99.4% despite the direct nitriding method. this is,
This is due to the sintering promoting action of yttria. But,
The brightness is only N6. This seems to be due to the action of the sintering aid.

In Comparative Example 2, the compact was produced by the cold isostatic pressing method, but the relative density was 98.2% and the lightness was still large.

In Comparative Example 3, high-purity aluminum nitride powder obtained by direct nitriding was hot-press sintered at 200 kgf / cm ² and 1900 ° C., but the relative density was only 97.0% and only a white powder was obtained. Did not. Such powders require even higher pressures.

In Example 1, although the powder obtained by the direct nitriding method was used and did not contain a sintering aid, the pressure during hot pressing was increased to 400 kg / cm ² to suppress the growth of particles, We succeeded in accelerating densification to a relative density of 99.4%. As a result, a black-gray sintered body having a brightness of N3.5 was successfully obtained.

(Comparative Examples 4 to 6) An aluminum nitride sintered body was manufactured in the same manner as in Comparative Examples 1 to 3. As a raw material, an aluminum nitride powder produced by the above-described reduction nitriding method was used.

In Comparative Examples 4 and 5 shown in Table 2, the yttria was 3
In Comparative Example 6, a high-purity aluminum nitride powder containing no yttria was used.

In Comparative Example 4, a raw material powder was uniaxially pressed to produce a preform, which was then hot-pressed. When hot pressing sintering, a pressure of 200 kgf / cm ^2,
It was baked at 1900 ° C. for 2 hours. In Comparative Examples 5 and 6, the preformed body was cold isostatically pressed at a pressure of 7 tf / cm ² to obtain a formed body. The formed body was housed in a sagger made of boron nitride and heated at 1900 ° C. for 3 hours. It was calcined at normal pressure for hours.

Then, the same measurement as described above was performed on the aluminum nitride sintered bodies of the respective examples. Table 2 shows the measurement results. However, in Comparative Examples 4 and 5 in which the addition amount of Y ₂ O ₃ was 3% by weight, the theoretical density of the sintered body was 3.29 g / c.

As can be seen from Table 2, in Comparative Example 4, the yttria was 3
Using raw material powder containing 200% by weight, 200kgf / cm ² ,
Hot press sintering is performed at 1900 ° C, and the relative density of the sintered body is 99.4%. Therefore, as for the aluminum nitride powder containing yttria, there is no change in the relative density of the sintered body in the case of the direct nitriding method and the case of the reduction nitriding method. However, also in Comparative Example 4, the brightness of the sintered body was 5.5 and the color tone was gray.

In Comparative Example 5, the raw material powder containing 3% by weight of yttria was fired at normal pressure, but the relative density was 98.8% and the brightness was high.

In Comparative Example 6, a high-purity aluminum nitride powder with a small amount of impurities was used without adding an additive such as yttria, but when fired under normal pressure, only a material having a low relative density was obtained. Also, only a white sintered body was obtained.

(Comparative Examples 7 to 9) Aluminum nitride sintered bodies were manufactured in the same manner as Comparative Examples 1 to 3. As a raw material, a high-purity aluminum nitride powder containing no yttria, produced by the above-described reduction nitriding method, is used, and the raw material powder is uniaxially pressed to produce a preform, which is then placed under a nitrogen atmosphere. Hot press firing.

In the case of hot press firing, in Comparative Example 7, 50 kg
A pressure of f / cm ² was applied and firing was performed at 1900 ° C. for 2 hours. In Comparative Example 9, a pressure of 100 kgf / cm ² was applied and firing was performed at 1900 ° C. for 2 hours. In Comparative Example 9, a pressure of 100 kgf / cm ² was applied, and 1900 ° C.
For 2 hours.

The same measurement as described above was performed on the aluminum nitride sintered body of each example. Table 3 shows the measurement results.

In Comparative Example 7, since the pressure was as low as 50 kg / cm ² , sintering did not proceed sufficiently, the relative density of the sintered body was 91.1%, and the color tone of the sintered body would be white. .

In Comparative Example 8, the pressure was 100 kg / cm ² and the temperature was 1800
Although the temperature was in ° C, sintering did not proceed sufficiently, the relative density of the sintered body was 96.3%, and the color tone of the sintered body would be light gray.

In Comparative Example 9, the pressure was 100 kg / cm ² and the temperature was 1900
° C, the relative density of the sintered body becomes 99.1%,
The color tone of the sintered body may be light gray.

(Examples 2 to 5) An aluminum nitride sintered body was manufactured in the same manner as in Comparative Examples 7 to 9. As a raw material, a high-purity yttria-free aluminum nitride powder produced by the above-described reduction nitriding method is used, and the raw material powder is uniaxially pressed to produce a preform, which is then hot-pressed in a nitrogen atmosphere. Press firing. However, the firing temperature, the holding time, and the pressing force were changed as shown in Table 4.

The same measurement as described above was performed on the aluminum nitride sintered body of each example. Table 4 shows the measurement results. FIG. 1 shows the relationship between the brightness N and the relative density of each sintered body for Comparative Examples 7, 8, 9 and Examples 2 and 3.

As shown in Table 4, in Example 2, when the compact formed from the above-described aluminum nitride raw material powder was hot-pressed, the compact was fired at 1800 ° C. and a pressure of 200 kg / cm ² for 2 hours. Has a light gray of N3.5 and a relative density of
99.4%, and the average particle size was 0.6 μm. It is considered that sintering proceeded sufficiently under these conditions, and the pressure was relatively large as the sintering temperature of 1800 ° C., thereby suppressing the growth of particles.

In Example 3, although sintering was performed at 1900 ° C. and a pressure of 200 kg / cm ² for 2 hours, the brightness of the sintered body was black gray of N3, the relative density was 100%, and the average particle size was 1.1 μm. Met. Under these conditions, sintering further progressed as compared with Example 2,
Although some grain growth is observed, the brightness of the sintered body is much lower.

In Example 4, although sintering was performed at 1900 ° C. and a pressure of 120 kg / cm ² for 2 hours, the brightness of the sintered body was black gray of N3.5, the relative density was 99.4%, and the average particle size was 99.4%. It was 2.7 μm.
Under this condition, it is considered that the brightness slightly increased because the growth of the particles slightly progressed as compared with Example 3.

In Example 5, although the sintered body was fired at 1950 ° C. and a pressure of 150 kg / cm ² for 2 hours, the brightness of the sintered body was black gray of N3.5, the relative density was 99.7%, and the average particle size was 99.7%. 3.0 μm.
Under these conditions, the firing temperature is higher and the pressing force is lower than in Example 3, so that the growth of the particles slightly proceeds easily.
It is considered that the brightness was slightly lower.

Further, in Example 3, although the relative density of the sintered body was 100.0%, the infrared transmittance was 26%.

(Examples 6 and 7 and Comparative Examples 10 and 11) The aluminum nitride sintered bodies of Examples 6 and 7 and Comparative Example 10 were manufactured in the same manner as Comparative Examples 7 to 9. As a raw material, a high-purity yttria-free aluminum nitride powder produced by the above-described reduction nitriding method is used, and the raw material powder is uniaxially pressed to produce a preform, which is then hot-pressed in a nitrogen atmosphere. Press firing. However, the firing temperature, the holding time, and the pressure were changed as shown in Table 5. In Comparative Example 11, the sintered body of Example 3 described above was further heat-treated at 1950 ° C. for 2 hours in a nitrogen atmosphere to produce a sintered body.

The same measurement as described above was performed on the aluminum nitride sintered body of each example. Table 5 shows the measurement results.

In Example 6, the firing temperature was 1850 ° C., the holding time was 2 hours, and the pressure was 120 kg / cm ² . The relative density of this sintered body was 99.3%, and the brightness was N4.
When the average particle size of the sintered body was measured, 3.
It was 1 μm.

In Example 7, the firing temperature was 1900 ° C., the holding time was 5 hours, and the pressure was 200 kg / cm ² . The bulk density of this sintered body was 3.26 g / cm ² , the same as that of Example 3, but the brightness increased to N4. Further, when the average particle diameter of the sintered body was measured, it was 3.8 μm, and it was found that the particle growth was progressing as compared with Example 3. It is considered that the lightness of the sintered body increased due to the growth of the particles.

In Comparative Example 10, the sintered body was fired at a temperature of 1950 ° C. at a pressure of 200 kg / cm ² for 7 hours, and the brightness of the sintered body was gray of N5, the relative density was 99.1%, and the average particle diameter was 99.1%. Is 3.2 μm
Met. Under these conditions, as compared with Example 3, baking is progressing too much, and as a result, the brightness of the sintered body is increased.

In Comparative Example 11, the sintered body of Example 3 was further
Heat treatment was performed at 50 ° C. for 2 hours at normal pressure under a nitrogen atmosphere. As a result, the bulk density of the sintered body after the heat treatment was 3.26 g / cm ² , which was the same as before the heat treatment, but the color tone became gray,
Brightness increased to N5. The average particle size of the sintered body was measured and found to be 4.2 μm. Thus, even when heat treatment is performed at normal pressure, if heat treatment is performed for a relatively short time, oversintering does not occur, but particle growth occurs,
As a result, the color tone of the sintered body changed to gray.

(Wafer Heating Experiment) A plate having a diameter of 210 mm and a thickness of 10 mm was prepared from the aluminum nitride sintered body manufactured according to Example 3 of the present invention, and this plate was placed in a vacuum chamber equipped with a heating mechanism using an infrared lamp. installed. 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 lamps, 20 infrared lamps each 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. Infrared rays emitted from each infrared lamp pass directly or after being reflected by a reflector, pass through a circular quartz window (250 mm in diameter, 5 mm in thickness) provided in a vacuum chamber, and reach an aluminum nitride plate. Heat this plate.

In this heating device, each infrared lamp is heated,
The temperature of the plate was increased from room temperature to 700 ° C. for 11 minutes, and held at 700 ° C. for 1 hour, after which the infrared lamp was stopped and the plate was gradually cooled. As a result, the power consumption of the infrared lamp was a maximum of 8600 W, 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 Examples 4 and 5, and the same results as described above were obtained.

Next, a plate was manufactured using the aluminum nitride sintered body of Comparative Example 1, and the same experiment as above was performed. this is,
It is a white aluminum nitride sintered body fired at 1900 ° C and having a density of 99.4%. At this time, the power consumption reached a maximum of 10 kW, and the temperature rise time was delayed by about 2 minutes. Further, as described above, when the thermal cycle of increasing and decreasing the temperature between room temperature and 700 ° C. was repeated, disconnection of the infrared lamp was likely to occur.

When the temperature of the silicon wafer was measured, the temperature of the silicon wafer was 593 ° C. when the temperature of the plate was maintained at 700 ° C., and the temperature of the silicon wafer also decreased compared to the above-described present invention. Turned out to be.

As can be seen from the above results, the aluminum nitride according to the present invention has a good infrared absorbing ability, is stable, and has excellent radiation ability when heating a wafer, as compared with white aluminum nitride. ing.

In the foregoing description, the present invention has been described with reference to particular embodiments, but the specific details illustrated are merely exemplary and may depart from the true spirit and scope of the following claims. Rather, it should be understood that it can be implemented in other ways.

INDUSTRIAL APPLICABILITY The aluminum nitride sintered body and the method of manufacturing the same according to the present invention provide a heating member such as a ceramic heater and a susceptor, in particular, a heating member (ceramic heater, ceramic susceptor, The present invention can be suitably applied to a ceramic electrostatic chuck, a ceramic susceptor having a built-in high-frequency metal electrode, and the like.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-223070 (JP, A) JP-A-63-85055 (JP, A) JP-A-60-239366 (JP, A) 279264 (JP, A) JP-A-6-16404 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C04B 35/581

Claims (20)

(57) [Claims] 1. An aluminum nitride sintered body characterized in that the content of all metal elements except aluminum is 100 ppm or less, and the brightness specified in JIS Z 8721 is black, N4 or less. 2. The aluminum nitride sintered body has a relative density of 99.3.
% Of the aluminum nitride sintered body according to claim 1. 3. The aluminum nitride sintered body according to claim 2, wherein the average particle diameter of crystal grains constituting said aluminum nitride sintered body is 4.0 μm or less and 0.6 μm or more. 4. The aluminum nitride sintered body according to claim 3, wherein the average particle diameter of crystal grains constituting said aluminum nitride sintered body is 3.0 μm or less. 5. The aluminum nitride sintered body according to claim 4, wherein the average particle diameter of crystal grains constituting said aluminum nitride sintered body is 2.0 μm or less and 1.0 μm or more. 6. A high-purity process member for a high-purity process in which the influence of a metal element other than aluminum is to be suppressed, wherein the aluminum nitride sintered material according to any one of claims 1 to 5. A member for a high-purity process, wherein the body is used as a substrate. 7. A high-purity process member characterized by being used for a high-purity process in which the effects of a group Ia element, a group IIa element and a transition metal element are to be prevented. 8. The high-purity process member according to claim 7, wherein the high-purity process member is installed in a semiconductor manufacturing apparatus. 9. The high-purity process member according to claim 8, wherein the high-purity process member is exposed to a halogen-based corrosive gas in the semiconductor manufacturing apparatus. 10. The high-purity process member according to claim 8, wherein the member is for installing and heating a semiconductor wafer. 11. The ceramic heater according to claim 10, wherein the high-purity process member is a ceramic heater including the base material and a resistance heating element embedded in the base material. Heating member. 12. The high-purity processing member according to claim 10, wherein said high-purity processing member is a susceptor for installing a semiconductor wafer. 13. The high-purity process member according to claim 12, wherein said susceptor is a susceptor heated by a ceramic heater or an infrared lamp. 14. The member for a high-purity process according to claim 12, wherein the susceptor is a susceptor including the base material and a high-frequency metal electrode built in the base material. . 15. The high-purity process member is a ceramic electrostatic chuck comprising the base material and an electrostatic chuck electrode embedded inside the base material. Item 11. The heating member according to Item 10. 16. A method for producing an aluminum nitride sintered body, comprising sintering aluminum nitride powder obtained by a reduction nitriding method at a temperature of 1800 ° C. or more and a pressure of 120 kg / cm ² or more. 17. The method for producing an aluminum nitride sintered body according to claim 16, wherein said aluminum nitride powder is sintered at a temperature of 2000 ° C. or less. 18. The method according to claim 18, wherein the aluminum nitride powder is 200 kg / cm ²
17. The method for producing an aluminum nitride sintered body according to claim 16, wherein sintering is performed at the above pressure. 19. The method according to claim 16, wherein the aluminum nitride powder is sintered for 2 hours or more and 5 hours or less.
A method for producing the aluminum nitride sintered body according to the above. 20. When sintering an aluminum nitride powder having a content of metal elements other than aluminum of 100 ppm or less to obtain a sintered body, the relative density of the sintered body is reduced.
A method for producing an aluminum nitride sintered body, wherein the average particle diameter of crystal grains forming the sintered body is 4.0 μm or less and 0.6 μm or more.