JP3611951B2 - Method for firing aluminum nitride - Google Patents

Description

【００５２】
（比較例１）
本発明例１と同様にして焼成体を得、各Ｒ／Ｂ値を示す面積の各百分率（％）を測定した。ただし、本発明例１において、雰囲気として１００％の窒素ガスを使用し、かつ窒素ガスの圧力Ｐ_１ を６００トールとし、Ｐ_２ を２．５ａｔｍとした。この結果を表１に示す。
【００５３】
（本発明例２）
本発明例１と同様にして焼成体を得、各Ｒ／Ｂ値を示す面積の各百分率（％）を測定した。ただし、本発明例１において、雰囲気として１０％の一酸化炭素を使用し、かつ一酸化炭素の圧力Ｐ_１ を６００トールとし、Ｐ_２ を６ａｔｍとした。この結果を表１に示す。
【００５４】
（比較例２）
本発明例１と同様にして焼成体を得、各Ｒ／Ｂ値を示す面積の各百分率（％）を測定した。ただし、本発明例１において、雰囲気として１００％の窒素ガスを使用し、かつ窒素ガスの圧力Ｐ_１ を６００トールとし、Ｐ_２ を６ａｔｍとした。この結果を表１に示す。
【００５５】
（本発明例３）
本発明例１と同様にして焼成体を得、各Ｒ／Ｂ値を示す面積の各百分率（％）を測定した。ただし、本発明例１において、雰囲気として１％の一酸化炭素を使用し、かつ一酸化炭素の圧力Ｐ_１ を６００トールとし、Ｐ_２ を２．５ａｔｍとした。この結果を表１に示す。
【００５６】
また、各例について、各Ｒ／Ｂ値と、各Ｒ／Ｂ値を示す部分の面積の百分率との関係を、図４にグラフとして示す。
【００５７】
これらの結果から判るように、本発明例によれば、Ｒ／Ｂ値の範囲が明らかに狭くなっており、色調のムラが全体として顕著に抑制されている。また、一酸化炭素の分圧を上昇させることによって、Ｒ／Ｂ値が全体として著しく減少しており、つまり窒化アルミニウム焼成体が黒色化していることが判る。
【００５８】
【発明の効果】
以上述べたように、本発明によれば、窒化アルミニウム焼成体の特に外観における色彩のムラを抑制できる。
【図面の簡単な説明】
【図１】本発明の焼成方法を実施するのに好適なホットプレス装置の一例を概略的に示す断面図である。
【図２】本発明の焼成方法を実施するのに好適なホットプレス装置の他の例を概略的に示す断面図である。
【図３】本発明例１、２、３および比較例１、２において採用した焼成スケジュールを示すグラフである。
【図４】本発明例１、２、３および比較例１、２において、焼成体の研磨面を画像処理して得られたＲ／Ｂ値と、各Ｒ／Ｂ値を示す部分の面積の百分率との関係を示すグラフである。
【符号の説明】
１、１１ 上パンチ ２、１２ 受け台 ３、１３ 型
４Ａ、４Ｂ、１４Ａ、１４Ｂ スリーブ ５、５Ａ、５Ｂ スペーサー ８、１８Ａ、１８Ｂ、１８Ｃ 被焼成体[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for firing aluminum nitride with little color unevenness or deviation.
[0002]
[Prior art]
The present applicant has disclosed a ceramic heater in which a wire made of a refractory metal is embedded in a dense ceramic substrate (Japanese Patent Laid-Open No. 3-261131). The wire is spirally wound inside the disk-shaped base material, and terminals are connected to both ends of the wire. Such ceramic heaters have been found to have excellent characteristics especially for semiconductor manufacturing.
[0003]
As ceramics constituting the base of the ceramic heater, nitride ceramics such as silicon nitride, aluminum nitride and sialon are considered preferable. In some cases, a susceptor is installed on a ceramic heater, a semiconductor wafer is installed on the susceptor, and the semiconductor wafer is heated. The present applicant has disclosed that aluminum nitride is preferable as a base material for such ceramic heaters and susceptors (Japanese Patent Laid-Open No. 5-101871). Particularly in semiconductor manufacturing equipment, halogen-based corrosive gases such as CF ₃ are frequently used as etching gas and cleaning gas. From the viewpoint of corrosion resistance against these halogen-based corrosive gases, aluminum nitride has extremely high corrosion resistance. It is because it was confirmed that it has.
[0004]
[Problems to be solved by the invention]
However, since the aluminum nitride fired body is likely to cause color unevenness, and in this case, there is a risk of affecting the price of goods, it has been desired to suppress color unevenness or deviation.
[0005]
In particular, in aluminum nitride products that have a function of heating a semiconductor wafer, such as an aluminum nitride susceptor for holding a semiconductor wafer, an aluminum nitride electrostatic chuck, and an aluminum nitride heater, the color of aluminum nitride is black. It is required to improve the radiation efficiency by bringing them closer. For this reason, the present applicant disclosed in Japanese Patent Application No. 7-218158 a blackened aluminum nitride fired body having a brightness of 4 or less, and further a brightness of 3 or less. However, as the inventors further studied, in the case of such a sintered body with low brightness, color unevenness tends to be more noticeable.
[0006]
An object of the present invention is to suppress color unevenness particularly in the appearance of an aluminum nitride fired body.
[0007]
[Means for Solving the Problems]
In the present invention, when firing a body to be fired of aluminum nitride, carbon monoxide is contained at a partial pressure of 0.6 atm or more in an atmosphere around the body to be fired at the time of firing. The present invention relates to a method for firing aluminum nitride, characterized in that an aluminum nitride fired body obtained by firing the body is blackened.
[0008]
Examples of the body to be fired in the present invention include an aluminum nitride powder, a molded body of this powder, a degreased body and a calcined body of this molded body.
[0009]
By including carbon monoxide in the atmosphere at the time of firing aluminum nitride, the present inventor reduces color unevenness or deviation in the appearance of the aluminum nitride after firing, and as a whole has a certain color tone than before. It has been found that an aluminum nitride fired body can be obtained.
[0010]
The reason why such an effect is obtained is estimated as follows. Regarding the physical properties, light absorption characteristics, crystal structure, etc. of the black aluminum nitride sintered body obtained by hot press sintering a high-purity aluminum nitride powder under specific conditions, the present applicant has disclosed JP-A-9-110405. Disclosed in. The results of this study will be briefly described. As a feature of the blackened aluminum nitride sintered body, for example, an AlON phase having a diameter of about 0.1 μm is present in an AlN particle having a particle diameter of 1 to 3 μm, and a graphite phase is further present.
[0011]
From the analysis by ESR of such a blackened aluminum nitride sintered body, it is presumed that the nitrogen atom coordinated to aluminum is substituted by aluminum and an aluminum-aluminum bond is formed. Such a bond is presumed to have a metal-bonding property that absorbs visible light having a wide range of continuous wavelengths, and this causes a reduction in the brightness of aluminum nitride.
[0012]
And, for example, when an alumina film is present on the surface of the aluminum nitride particles, the atmosphere inside the film made of graphite foil is made a reducing atmosphere and sintered. CO gas is generated by the reaction between Al ₂ O ₃ remaining in the carbon and C (carbon). Gas phase (gas) species in this reaction are Al, AlO, Al ₂ O, Al ₂ O ₂ , AlC, AlC ₂ , Al ₂ C ₂ , AlN, NO, CO.
[0013]
When the partial pressure of CO in the sintered body is made constant and the equilibrium partial pressure of each gas phase species is calculated, the partial pressure is reduced in the order of AlN, Al, and Al ₂ O. The reduction reaction of Al ₂ O ₃ proceeds by carbon, and AlN is generated. Further, as can be seen from the partial pressures of Al and Al ₂ O, it is presumed that an ALON (AlN + Al ₂ O) phase containing Al—Al bonds and oxygen is generated in the crystal lattice.
[0014]
At 1950 ° C. or lower, the Al type has a higher partial pressure than the Al ₂ O type, but when the temperature exceeds 1950 ° C., the magnitudes of both partial pressures are reversed. That is, it is presumed that the higher the firing temperature, the more the Al ₂ O phase is formed, and an Al—Al bond is generated at 1950 ° C. or lower.
[0015]
In the color tone of the AlN crystal, the defect structure inside the crystal is important. As described above, this defect structure includes the oxygen content in the raw material powder, the atmosphere during sintering, and the gas phase generated in the sintering process. Mainly affected by species. Then, as described above, reduction of the oxide by carbon occurs, and an AlN phase, an Al phase, and an AlO ₂ phase are generated, and it is considered that an ALON phase and an Al—Al bond are generated.
[0016]
In this process, it is considered that a trace component, particularly a carbon component, remaining in the fired body after the firing of aluminum nitride affects the color tone and brightness of the aluminum nitride. When aluminum nitride is fired, the trace components from the body to be fired react with the adsorbed water in the furnace and oxygen in the raw material to become CO gas. It is considered that the amount of released components is suppressed, or the amount of trace components released from each part of the fired body is made uniform throughout the body to be fired. Thus, it is presumed that the generation of the ALON (AlN + Al ₂ O) phase containing Al—Al bonds and oxygen as described above is easily uniformed over the entire surface of the object to be fired.
[0017]
In the present invention, carbon monoxide needs to be contained in an atmosphere in contact with at least the surface of the body to be fired at least during the liquid phase generation, sintering, and solidification in the firing stage.
[0018]
Here, it is preferable that the atmosphere is substantially composed of carbon monoxide and an inert gas. Here, “substantially” means that inevitable impurities are allowed.
[0019]
In the present invention, it is preferable that carbon monoxide is contained in the atmosphere from a temperature of 300 ° C. or lower to the maximum temperature during firing and from the maximum temperature to the ceramic solidification temperature. As a result, the color unevenness of aluminum nitride is particularly reduced. This is particularly effective when the amount of carbon in the aluminum nitride raw material is limited as described later. The reason is that AlN is not generated, Al ₂ O ₃ , Al is generated, and finally, an AlON phase and an Al—Al bond are more likely to be generated in the crystal lattice. This effect becomes stable.
[0020]
Further, it has been found that the lightness of the color of aluminum nitride is remarkably lowered by setting the partial pressure of carbon monoxide in the atmosphere to 0.6 atm or more.
[0021]
In the present invention, it is preferable to cover the surface of the body to be fired with an airtight firing member. As the form of such an airtight member for firing, sheet-like ones such as sheets and foils are preferable.
[0022]
The present invention contains a black-gray to black-brown nitridation that contains almost no metal element other than aluminum, such as a blackening agent, and has a blackness of N4 or less as defined in JIS Z 8721. It is particularly suitable for the production of an aluminum fired body. This aspect will be specifically described.
[0023]
The present inventor prepared a raw material made of an aluminum nitride powder having a carbon content of 200 ppm to 5000 ppm, and this was subjected to a temperature of 1730 ° C. or higher and a pressure of 80 kg / cm ² or higher by a hot press method or a hot isostatic press method. Was sintered. This succeeded in producing a black-brown or black-gray aluminum nitride substrate with low brightness. This aluminum nitride fired body is described in Japanese Patent Application No. 7-218158.
[0024]
Here, in order to prepare the raw material which consists of aluminum nitride powder whose carbon content is 200 ppm-5000 ppm, there exists the following method.
[0025]
(1) The carbon content in the powder is adjusted to 200 to 5000 ppm by adding a predetermined amount of a carbon source to the aluminum nitride powder.
(2) The raw material which consists of aluminum nitride powder whose carbon content is 200 ppm-5000 ppm is manufactured by mutually mixing several types of aluminum nitride powder from which carbon content differs. In this case, three or more types of aluminum nitride powder can be mixed. However, in a preferred embodiment, the carbon content is 200 ppm to 5000 ppm by mixing the first aluminum nitride powder having a relatively low carbon content and the second aluminum nitride powder having a relatively high carbon content. The raw material which consists of aluminum nitride powder which is is manufactured.
[0026]
As the carbon source added to the aluminum nitride powder, the following can be preferably used.
(1) Resin containing carbon. For example, organic resin made of organic resin powder such as phenol resin.
(2) Carbon powder such as carbon black and graphite.
(3) An intermediate product of aluminum nitride having a high carbon concentration produced in the process of reduction nitriding or the like.
[0027]
As a method of mixing the aluminum nitride powder and the carbon source, dry bag mixing, dry mixing such as a ball mill and a vibration mill, and wet mixing using an organic solvent can be used.
[0028]
Thus, by sintering aluminum nitride powder containing a predetermined proportion of carbon under a high pressure and a temperature in a predetermined range, an aluminum nitride fired body with low brightness can be produced stably. Here, when the carbon ratio is less than 200 ppm, the lightness of the fired body is increased, and when it exceeds 5000 ppm, the relative density of the aluminum nitride fired body is reduced to less than 92%, and the color tone becomes gray. .
[0029]
Further, it was found that if the firing temperature is less than 1730 ° C., the fired body is not sufficiently densified, the aluminum nitride fired body becomes white, and the brightness increases to 7 or more. When the firing temperature of the powder exceeded 1950 ° C., a polytype phase was also generated, and the brightness of the aluminum nitride fired body was increased. When the firing temperature was in the range of 1750 to 1900 ° C., the brightness of the aluminum nitride fired body was particularly reduced.
[0030]
Further, when the pressure during firing is less than 80 kg / cm ² , an AlN—Al ₂ CO crystal phase is generated or a polytype phase is generated in addition to the AlN crystal phase, and the brightness of the aluminum nitride sintered body is increased. I found it to rise. This pressure is preferably 150 kg / cm ² or more, and more preferably 200 kg / cm ² or more. However, this pressure is preferably 0.5 ton / cm ² or less in view of the actual capability of the apparatus.
[0031]
In the present embodiment, addition of metal elements other than aluminum should be avoided in the raw material made of aluminum nitride powder, preferably 100 ppm or less. Here, “a metal element other than aluminum” refers to a metal element belonging to Ia to VIIa, VIII, Ib, IIb of the periodic table and a part of elements belonging to IIIb, IVb (Si, Ga, Ge, etc.).
[0032]
Here, lightness will be described. The surface color of the object is displayed by hue, brightness, and saturation, which are three attributes of color perception. Among these, the brightness 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, where the ideal black lightness is 0 and the ideal white lightness is 10. Each color is divided into 10 parts between the ideal black and the ideal white so that the perception of the brightness of the color is a uniform rate, and is displayed with symbols N0 to N10. When measuring the brightness of an actual aluminum nitride sintered body, the 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. To do. At this time, in principle, the lightness is determined to the first decimal place, and the value of the first decimal place is 0 or 5.
[0033]
The aluminum nitride ceramic obtained by the present invention is particularly useful as a base material for semiconductor manufacturing equipment. For example, a ceramic heater in which a resistance heating element is embedded in an aluminum nitride base material, and an electrostatic chuck electrode in the base material Active such as ceramic electrostatic chuck with embedded electrode, heater with electrostatic chuck with resistance heating element and electrode for electrostatic chuck embedded in substrate, electrode device for high frequency generation with plasma generating electrode embedded in substrate It can be used as a base material for mold devices.
[0034]
Furthermore, a susceptor for installing 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 for supporting a semiconductor wafer It can be used as a base material for each semiconductor manufacturing apparatus such as lift pins and shower plates.
[0035]
Hereinafter, a hot press firing apparatus suitable for carrying out the method of the present invention will be described with reference to the schematic sectional views of FIGS. 1 and 2.
[0036]
In FIG. 1, sleeves 4 </ b> A and 4 </ b> B having a substantially semicylindrical shape are accommodated so as to contact the inner side surface 3 a of the mold 3. In FIG. 1, the sleeve is divided into two parts so that the fired product can be easily taken out from the mold 3 after firing. The sleeve can also be divided into three or more.
[0037]
The upper punch 1 can be moved toward the uniaxial direction (vertical direction in FIG. 1) along the inner surface 4a of the sleeves 4A and 4B. A cradle 2 is installed and fixed below the sleeves 4A and 4B, and the pressurizing surface 1a of the upper punch 1 and the pressurizing surface 2a of the cradle 2 are opposed to each other, so that a space for hot pressing is provided. Is forming.
[0038]
A spacer 5 </ b> A is installed inside the pressure surface 1 a of the upper punch 1, and a spacer 5 </ b> B is installed inside the pressure surface 2 a of the cradle 2. The to-be-fired body 8 is accommodated between the spacers 5A and 5B.
[0039]
Carbon firing members 7 are installed between the pressure surface 8a of the object to be fired 8 and the spacer 5A, and between the pressure surface 8b and the spacer 5B, respectively. A firing member 6 is disposed between the non-pressurized surface 8c of the body 8 to be fired and the inner side surfaces 4a of the sleeves 4A and 4B. The to-be-fired body 8 is covered with the firing members 6 and 7, and for this reason, it is not in direct contact with the sleeve and the spacer.
[0040]
In the firing apparatus of FIG. 2, sleeves 14 </ b> A and 14 </ b> B are provided so as to contact the inner surface 13 a of the mold 13. The inner surface 13a of the mold 13 is provided with a certain taper, and the inner surfaces 14a of the sleeves 14A and 14B extend straight from the upper side to the lower side in FIG.
[0041]
The cradle 12 is fixed to the lower side of the mold 13 and the sleeves 14A and 14B. In the sleeves 14A and 14B, for example, four spacers 5 and three objects to be fired 18A, 18B, and 18C are accommodated between the upper punch 11 and the cradle 12. The spacer 5 is in contact with the pressure surface 11 a of the upper punch 11 and the pressure surface 12 a of the cradle 12.
[0042]
Between each spacer 5 and each pressing surface 18a, 18b of each unfired product 18A, 18B, 18C, a planar firing member 17 is interposed. Between the non-pressurized surface of each spacer 5 and the non-pressurized surface 18c of each unfired product and the sleeves 14A and 14B, a planar firing member 16 is provided.
[0043]
【Example】
Hereinafter, more specific experimental results will be described.
(Invention Example 1)
Using the hot press apparatus shown in FIG. 1, a firing experiment was conducted. As the aluminum nitride raw material, high-purity powder produced by a reduction nitriding method was used. In each powder, the contents of Si, Fe, Ca, Mg, K, Na, Cr, Mn, Ni, Cu, Zn, W, B, and Y are each 100 ppm or less, and metals other than aluminum are other than these. Not detected. The carbon content was 250 ppm.
[0044]
1.8 kg of aluminum nitride powder was weighed to prepare a uniaxial press mold having a diameter of 215 mm. A barrel mold and a lower mold of a uniaxial press apparatus were set, and the powder was put into the mold. The powder was leveled using a predetermined leveling machine, and the upper mold was set. Pressing at a pressure of 200 kg / cm ² for 2 minutes, the upper mold was pulled up, and a disk-shaped molded body having a diameter of 215 mm and a thickness of 30 mm was obtained. At this time, a molybdenum mesh was embedded in the disk-shaped molded body.
[0045]
On the other hand, a dummy spacer having a diameter of 214.8 mm was placed on the surface 2 a of the cradle 2, and the disk-shaped molded body 8 was placed on the dummy spacer. At this time, the periphery of the disk-shaped molded body 8 was completely surrounded by the flexible graphite sheets 6 and 7. The two-divided sleeves 4A and 4B and the mold 1 were placed on these and accommodated in a firing furnace in this state.
[0046]
The schedule at the time of baking is shown in FIG. In FIG. 3, graphs A, B, and C indicate temperature, pressure on the molded body, and atmospheric pressure, respectively. The abscissa indicates the elapsed time, and the ordinate indicates the temperature, the pressure on the compact, and the atmospheric pressure in order from the top.
[0047]
First in vacuo and at room temperature, the pressure S ₁ of the molded body 2 tons. Next, the temperature was increased from room temperature to 300 ° C. at a rate of 700 ° C./hour (time t ₁ ). Until time t ₂ , carbon monoxide at 300 ° C. and P ₁ = 600 torr was introduced, and the vacuum was returned from time t ₂ to time t ₃ .
[0048]
Next, a mixed gas of N ₂ and CO was introduced from time t _{3 at} P ₂ = 2.5 atm. The partial pressure of CO was 10%. Thereafter, the atmospheric pressure was maintained at 2.5 atm. Next, the temperature was increased from 300 ° C. to 1850 ° C. at a temperature increase rate of 250 ° C./hour. At this time, the pressure on the molded body was increased from time t ₄ when the temperature reached 1000 ° C., and at time t ₅ after 20 minutes, the pressure S ₂ on the molded body was set to 72.6 tons (200 kg / cm ² ). Then, until the time _{t 6,} at 1850 ° C., and held for 1 hour at 200 kg / cm ^2. Next, the temperature was decreased from 1850 ° C. at a rate of 300 ° C./hour, and the press pressure was released at 1400 ° C.
[0049]
In the fired body, the thickness from the mesh to the surface is 2 mm. The fired body was taken out from the mold and the sleeve, and the surface of the fired body on the mesh side was polished with a surface grinder using a # 400 diamond grindstone, so that the thickness from the mesh to the surface was 1 mm. . Next, machine oil was applied to the polished surface of the fired body.
[0050]
This polished surface was processed with an image processing apparatus, and the color tone of each part of the polished surface was measured. Specifically, the color tone of each part of the polished surface is displayed in three primary colors of R (red), G (green), and B (blue), and the R / B value (ratio of red and blue) at this time is displayed. It was measured. As the R / B value increases, the appearance becomes white, and as the R / B value decreases, the appearance becomes black. As shown in Table 1, the area of the part corresponding to each R / B value was measured, and each percentage (%) of the area showing each R / B value was displayed in Table 1.
[0051]
[Table 1]

[0052]
(Comparative Example 1)
A fired body was obtained in the same manner as in Invention Example 1, and each percentage (%) of the area showing each R / B value was measured. However, in Example 1 of the present invention, 100% nitrogen gas was used as the atmosphere, the pressure P _{1 of the} nitrogen gas was 600 Torr, and P ₂ was 2.5 atm. The results are shown in Table 1.
[0053]
(Invention Example 2)
A fired body was obtained in the same manner as in Invention Example 1, and each percentage (%) of the area showing each R / B value was measured. However, in Example 1 of the present invention, 10% carbon monoxide was used as the atmosphere, the carbon monoxide pressure P ₁ was 600 Torr, and P ₂ was 6 atm. The results are shown in Table 1.
[0054]
(Comparative Example 2)
A fired body was obtained in the same manner as in Invention Example 1, and each percentage (%) of the area showing each R / B value was measured. However, in Example 1 of the present invention, 100% nitrogen gas was used as the atmosphere, the pressure P _{1 of the} nitrogen gas was 600 Torr, and P ₂ was 6 atm. The results are shown in Table 1.
[0055]
(Invention Example 3)
A fired body was obtained in the same manner as in Invention Example 1, and each percentage (%) of the area showing each R / B value was measured. However, in Example 1 of the present invention, 1% carbon monoxide was used as the atmosphere, the pressure P ₁ of carbon monoxide was 600 Torr, and P ₂ was 2.5 atm. The results are shown in Table 1.
[0056]
Moreover, about each example, the relationship between each R / B value and the percentage of the area of the part which shows each R / B value is shown as a graph in FIG.
[0057]
As can be seen from these results, according to the example of the present invention, the range of the R / B value is clearly narrow, and the unevenness of the color tone is remarkably suppressed as a whole. It can also be seen that by increasing the partial pressure of carbon monoxide, the R / B value is significantly reduced as a whole, that is, the aluminum nitride fired body is blackened.
[0058]
【The invention's effect】
As described above, according to the present invention, it is possible to suppress color unevenness particularly in the appearance of the aluminum nitride fired body.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically showing an example of a hot press apparatus suitable for carrying out a firing method of the present invention.
FIG. 2 is a cross-sectional view schematically showing another example of a hot press apparatus suitable for carrying out the firing method of the present invention.
FIG. 3 is a graph showing firing schedules employed in Invention Examples 1, 2, and 3 and Comparative Examples 1 and 2.
FIG. 4 shows the R / B value obtained by image processing of the polished surface of the fired body and the area of the portion showing each R / B value in Invention Examples 1, 2, 3 and Comparative Examples 1, 2. It is a graph which shows the relationship with a percentage.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1,11 Top punch 2,12 Base 3,13 Type | mold 4A, 4B, 14A, 14B Sleeve 5, 5A, 5B Spacer 8, 18A, 18B, 18C To-be-fired body

Claims (5)

When firing the body to be fired of aluminum nitride, carbon monoxide is contained at a partial pressure of 0.6 atm or more in the atmosphere around the body to be fired during firing, and the body to be fired is fired. A method for firing aluminum nitride, characterized in that the obtained aluminum nitride fired body is blackened . The method for firing aluminum nitride according to claim 1, wherein the atmosphere is substantially composed of carbon monoxide and an inert gas. The carbon monoxide is contained in the atmosphere during firing from a temperature of 300 ° C. or lower to a maximum temperature during firing and from a maximum temperature to a ceramic solidification temperature. 3. The method for firing aluminum nitride according to 2. The to-be-fired body is a to-be-fired body made of an aluminum nitride powder having a carbon content of 200 to 5000 ppm by weight. The method for firing aluminum nitride according to any one of claims 1 to 3 , wherein sintering is performed at a pressure of not less than cm ^{2 and not} more than 0.5 ton / cm ² . The method for firing aluminum nitride according to claim 4 , wherein the amount of the metal element other than aluminum in the body to be fired is 100 ppm or less for each metal element.

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