JP2003048780A - Porous aluminum nitride - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a porous aluminum nitride, especially formed by reductively nitriding AlN polytypoid. SOLUTION: In this invention, it is noticed that a sintered compact in which plate-like crystals intertangle with one another and the pore distribution is uniform can be produced by reductively nitriding the AlN polytypoid because the AlN polytypoid, especially 27 R is a crystal having a plate-like form. The porous aluminum nitride having excellent quality is obtained by following two stage process, comprising (1) a first stage for producing a porous AlN polytypoid, and (2) a second stage for reducing the porous AlN polytypoid with carbon. The porous aluminum nitride has a porosity of 5 to 60% and pore diameter distribution of ○○ to ○○. Further, the porous aluminum nitride having a porosity of 5 to 60% is obtained by subjecting Al-Si-O-N-based AlN polytypoid to heat treatment in the presence of nitrogen and carbon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to porous aluminum nitride, and more particularly to porous aluminum nitride produced by reducing and nitriding porous AlN polytypoid.

[0002]

2. Description of the Related Art Aluminum nitride (AlN) is characterized by high thermal conductivity (-320 W / mK), excellent electrical insulation, and a coefficient of thermal expansion similar to that of silicon. The application as a filler to semiconductor encapsulation resin is expected. On the other hand, AlN
AlN polytypoids in which Al is replaced by Si and N is replaced by O have been studied in order to improve the corrosiveness and mechanical strength of AlN (eg, Yoneya K. et al .; Material Science 31 (19)).
94) 169-174). Regarding the AlN polytypoid porous body, 27R, which is the main phase of the sample of the AlN-SiO ₂ -based AlN polytypoid with the SiO ₂ addition amounts of 10% by weight and 15% by weight, has a high porosity and a small pore size. It has been elucidated that it is suitable for the formation of erythrocytes and that 27R exhibits plate-like crystal grains (K. Komeya, et. Al.
“Fabrication and Evaluation of Porous AlN Polytyp
^{oid "The 17 th International Korea-} Japan Semina on
Ceramics, 289-293 (2000)). Furthermore, studies were conducted to remove solid solution Si and O by heat treatment in a carbon reducing atmosphere, and it was clarified that the constituent phase was changed from AlN polytypoid to AlN by this heat treatment in a carbon reducing atmosphere. (K. Komeya, K. Wagatsuma, T.
Meguro ”Processing and Fabrication of Advanced Ma
terials VI ”volume 1, 947-953 (1998)).
It has not yet been clarified how a sintered body having such a plate-like crystal changes by heat treatment in a carbon-reducing atmosphere, and at the same time, the thermal conductivity, which is a characteristic of AlN, changes. Furthermore, the dielectric constant of aluminum nitride is about 8 to 9, which is higher than that of glass, plastic, air, and the like, which poses a problem that the propagation speed of electric signals is delayed.

[0003]

Therefore, the present inventors have made various properties such as porosity, constituent phase, microstructure, and thermal conductivity by heat-treating various AlN--SiO ₂ system sintered bodies in a carbon reducing atmosphere. A study was conducted to clarify the changes in the. Various attempts have been made to produce a porous body of aluminum nitride, but since porous aluminum nitride having fine and uniform pores has not been developed, the conditions for producing such a porous aluminum nitride are The purpose was to clarify.

[0004]

According to the present invention, since AlN polytypoid, particularly 27R, has plate-like crystals, a sintered body having plate-like crystals entangled with each other to have a substantially uniform pore distribution is produced. It is characterized in that it is possible to obtain a porous aluminum nitride body of excellent quality by the following two-step process. (1) Step of producing porous AlN polytypoid (2) Step of carbon reduction treatment of porous AlN polytypoid Further, the dielectric constant of aluminum nitride is about 8 to 9 and glass,
If aluminum nitride, which has higher thermal conductivity than plastics and air, can be made porous, the permittivity of air is 1, so that the permittivity of aluminum nitride can be reduced according to the complex rule. In accordance with this idea, it has succeeded in producing porous aluminum nitride having fine and uniform pores by nitriding and reducing the porous AlN polytypoid. Further, it has been known that a rare earth oxide or an alkaline earth compound is useful as a sintering aid for densifying AlN. However, by using such a sintering aid, the porosity of the present invention can be improved. The porosity of porous aluminum nitride can be controlled.

That is, the object of the present invention is to have a porosity of 5 to 60.
%, And to provide porous aluminum nitride having a pore size in the range of nano size to about 100 μm. Here, the nano size means a size on the order of nm, and specifically means a size of about 1 to 100 nm. The size of about 100 μm also means a size on the order of 100 μm, and specifically, a size of about 100 to 1000 μm. Another object of the present invention is Al-Si-O-N.
The object is to provide a porous aluminum nitride having a porosity of 5 to 60%, which is produced by heat treating an AlN polytypoid of the system in the presence of nitrogen and carbon. Here, in addition to nitrogen and carbon, hydrocarbon (C _x H _y (x and y are represented by appropriate positive numbers)) and NH ₃ may be present. It is preferable that 50% by weight or more of the AlN polytypoid is 27R, which is one of the polymorphs of the AlN polytypoid. The temperature at which this AlN polytypoid is heat-treated (that is, reductive nitriding) in the presence of nitrogen and carbon is 1700 to 2
It is preferably 050 ° C. The AlN polytypoid used for producing the porous aluminum nitride can be produced by firing a mixed system of AlN and SiO ₂ . This means that AlN and SiO ₂ are main components, and does not exclude the inclusion of other components or impurities. Also, AlN-S
The ratio of SiO ₂ in the iO ₂ system is 30 wt% or less, especially 5
It is preferably ˜20% by weight. Also, the AlN polytypoid can be synthesized from the precursor containing Al—Si—O—N by other methods. In addition, a rare earth oxide or an alkaline earth oxide may be added to the AlN polytypoid as a sintering aid, and the mixture may be fired. By adding this sintering aid, it becomes possible to control the porosity of the porous aluminum nitride. This sintering aid is yttria (Y
₂ O ₃ ), such as AlN
The ratio of rare earth compound to polytypoid is 10
It is preferably not more than wt%, particularly preferably 0.5 to 3.0 wt%.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION AlN polytypoids are a group of compounds having six kinds of long-period layered structures using wurtzite type AlN as a basic lattice in oxynitrides, and this phase is composed of AlN.
Al is replaced with Si and N is replaced with O, and the stacking cycle in the c-axis direction changes depending on the replacement amount. Al
The —Si—O—N AlN polytypoid is generally represented by the chemical formula M _m X _{m + 1} (where M is a metal atom, X is a non-metal atom, and m is an integer having a value of 4 to 11), and is 27.
R (7AlN ・ SiO ₂ ), 21R (6AlN ・ SiO 2
₂ ), 15R (4AlN · SiO ₂ ), 12R (5Al
N ・ SiO ₂ ), 8R (3AlN ・ SiO ₂ ), 2R
(AlN), 33R (10AlN · SiO ₂ ), 24R
(11AlN ・ SiO ₂ ), 39R (12AlN ・ Si
There is a polymorph of O ₂ ). The AlN polytypoid of the present invention may include any of these forms. Among them, the preferable AlN-SiO ₂ 27R polytypoid has m = 9 in the above formula, the composition is represented by 7AlN · SiO ₂ , and has a wurtz-type structure with a lattice constant a = 3.079Å, b
= 71.98Å, c / a = 2.67. This 27R
Since the polytypoid has a plate-like crystal, it is possible to produce a sintered body having a uniform pore distribution by intertwining the plate-like crystals as a sintered body. Therefore, the AlN polytypoid of the present invention contains 50% by weight or more of 27R. It is preferable to include.

The sintering aid of the present invention is preferably a rare earth oxide and an alkaline earth compound, preferably a rare earth oxide because it provides higher thermal conductivity and excellent electrical insulation.
More preferably, yttria (Y ₂ O ₃ ) can be used. CaO is a typical alkaline earth compound. Such a sintering aid has heretofore been used for densifying AlN. If a sintering aid is used, grain growth, pore growth, and porosity can be controlled.

The following two-step process for producing the porous aluminum nitride of the present invention will be described in detail below with reference to specific examples. (1) Step of producing porous AlN polytypoid (2) Step of carbon reduction treatment of porous AlN polytypoid The production of the AlN polytypoid of the first step (1) is not particularly limited and may be performed by a known method. Finally, it is preferable to adopt a method that finally contains a large amount of 27R, which is a plate-like crystal. As a raw material, it is preferable to use powder of AlN and SiO ₂ , and a rare earth element oxide (Y ₂ O ₃ or the like) may be added. Since the rare earth element oxide is densified, it works in the direction of lowering the porosity, so that the porosity can be controlled. Such a mixture is molded using an organic binder as appropriate, degreased at around 500 ° C., and then subjected to 17 in a non-oxidizing atmosphere (generally N ₂ atmosphere).
Bake at 00 to 1900 ° C. Next, in the second step (2), the porous AlN polytypoid produced in the first step is subjected to carbon reduction treatment. The reaction is carried out in a nitrogen atmosphere, and the pressure may be almost normal pressure. The reaction temperature is 1800 to 2050 ° C, preferably 1800 to 2000 ° C. When the treatment is performed within this temperature range, particularly in the case of AlN—SiO ₂ system, the porous shape (porosity and pore diameter) formed in the first step is almost maintained. The reaction time is usually within several hours, although it depends on the temperature and the collected amount. After conversion to AlN, some shrinkage may be observed.

[0009]

The present invention will be illustrated by the following examples.
Is not intended to be limited. Also, in the composition
In this regard, "%" means "% by weight" unless otherwise specified.
ItExample 1 1) Preparation of AlN polytypoid powder SiO listed in Table 1 below_Two5, 10, 15 weight of powder
%, The rest is AlN powder in the same table, and the total is 100% by weight.
Was prepared.

[Table 1] A peptizing agent (Celna E503) was added to these powders in an amount of 1% by weight based on the raw material powder, and 150 g of alumina balls having a diameter of 11 mm were used as a mixed medium in a 250 ml polyethylene pot, and the mixture was rotated by a ball mill using 200 ml of ethanol as a dispersion medium. Wet mixing was performed at a speed of 100 rpm for 6 hours.

After mixing, the alumina balls were removed and the sample was transferred to a porcelain dish, and ethanol was sufficiently evaporated with a mantle heater. After that, let the sample cool while still in the porcelain dish,
A 32 mesh nylon sieve was used for forced passing, and a 48 mesh nylon sieve was used for forced passing to obtain a mixed powder. Next, 1% by weight of paraffin (mp: 46 to 48 ° C.) with respect to the mixed powder was put in another porcelain dish, the porcelain dish was heated to melt the paraffin, and then cyclohexane was added thereto. 15 ml and the above mixed powder were added, and the mixture was stirred and dried so that the solution could permeate the whole powder. The obtained powder was allowed to cool and was forced to pass through a 48-mesh nylon sieve to produce a granulated powder.

Approximately 0.2 g of the granulated powder was placed in a stainless steel mold and uniaxially pressure-molded at 50 MPa for 15 seconds using a press machine of MP-500H manufactured by Riken Seiki Co., Ltd.
A molded body of φ15 × 0.7 mm was obtained. After placing the molded body on the alumina boat, the boat was charged into a degreasing furnace and
Degreasing was performed in an air stream at 3 ° C. for 3 hours. After degreasing, the diameter of the sample was measured using a caliper and the thickness was measured using a micrometer, and the sample was weighed using a precision electronic analytical balance. A Si ₄ N ₄ crucible was put in a graphite container, and the above-mentioned degreased body was put therein. This graphite container was inserted into a high temperature firing furnace Hi-Multi 5000 manufactured by Fuji Denpa Kogyo Co., Ltd., and the temperature was 1900 ° C. in a nitrogen atmosphere of 0.6 MPa.
Sintering was performed for 6 hours.

2) Production of porous aluminum nitride The obtained sintered body was put in a carbon crucible, and a transistor type high frequency induction heating device JTR-1 manufactured by JEOL Ltd.
0 at a temperature of 1900 ° C. to 2000 ° C. and a heat treatment time of 0
Heat treatment was performed in a nitrogen stream of 1 liter / min for ~ 3 hours. The temperature rise pattern is from room temperature to 1750 ° C at 60 ° C /
Min, from 1750 ° C. to the heat treatment temperature at 10 ° C./min. The heat treatment time of 0 hour means that after the heat treatment temperature is reached,
This means returning to room temperature immediately.

3) Evaluation method The bulk density d _b was calculated using the following Archimedes' equation (1).

[Equation 1] AlN easily reacts with water, so
-Butanol (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) was used. Here, W ₁ is dry weight, W ₂ : saturated water weight, W ₃ : underwater weight, ρ 1: water density at the time of measurement. The theoretical density of the sintered body is AlN (d = 3.26 g / cm ³ ), S
Using the composition ratio of io ₂ (d = 2.65 g / cm ³ ), the heat-treated sample was calculated from the theoretical density of AlN (d = 3.26 g / cm ³ ) because the constituent phase was AlN. The porosity was calculated by comparing with the bulk density of the obtained sintered body. X-ray diffractometer (XRD,
RAD-2R manufactured by Rigaku Denki Co., Ltd. was used. X-ray diffraction method, voltage 40KV, current 20mA, scanning speed 2 °
/ Min, divergence slit 1 °, light-receiving slit 0.3 mm, scanning angle (2θ) range 10 to 80 °. For the microstructure, a scanning electron microscope (SEM,
The microstructure was observed using JSM5200 manufactured by JEOL Ltd. Since the sample is an insulator, gold vapor deposition was performed using a product manufactured by JEOL Ltd. under the conditions of a voltage of 40 kV, a current of 20 mA and a holding time of 3 minutes.

The thermal conductivity κ is LF / T manufactured by Rigaku Denki Co., Ltd.
The thermal diffusivity was measured by a YAG laser using a CM-FA8510B laser flash method thermal constant measuring device, and calculated by the formula (2). κ = α × c × d (2) where α is the number of heat expansion targets, c is the specific heat, and d is the measured density.
The dimensions of the measurement sample were φ10.5 × 0.4 mm, and carbon spray was applied to the surface of the sample for surface treatment.

The pore size distribution was measured using a mercury porosimeter (Pore Master 33P-GT manufactured by Yuasa Ionics Co., Ltd.), and the sample was measured by the mercury injection method. Liquids with high surface tension, such as mercury, that are difficult to wet do not enter the small pores unless pressure is applied. At this time, between the pressure P and the minimum pore radius r that enters, π × r ² × P = −2π × r × γ × cos θ (3) That is, r × P = −2γ × cos θ (4) Have a relationship. Here, γ is the surface tension of mercury, and θ is the contact angle between mercury and the sample. Therefore, the pore size and the pore volume can be determined by measuring the mercury injection pressure and the volume at that time.

4) ResultsConstituent phase The heat treatment time is 0 to 3 hours, and the heat treatment temperature is 1900 to
XRD of constituent phases of each sample when changed to 2000 ° C
Table 2 shows the results of the identification and the porosity. Heat treatment
Time is 0 hours means that the temperature reaches room temperature immediately after reaching the heat treatment temperature.
Means to return to.

[Table 2] In this table, in the place where 27R + AlN before treatment was described, AlN was extremely small, whereas 27R was much more. For the samples with 5%, 10%, and 15% SiO ₂ addition, the composition phase before heat treatment was 27R + AlN, with 27R being the larger composition, but the heat treatment at 1900 ° C x 0 hours reduced 27R and increased AlN. is doing. Further, by heat treatment at 1900 ° C. for 1 to 3 hours and 2000 ° C. for 3 hours, all the samples with the SiO ₂ addition amounts of 5% by weight, 10% by weight, and 15% by weight are AlN. From this, it is considered that the discharge of Si and O is almost completed by the heat treatment of at least 1900 ° C. for 1 hour.

[0017]Porosity The heat treatment time for the AlN polytypoid sintered body is set to 3 hours.
And heat treatment was performed by changing the temperature to 1900 to 2000 ° C.
Fig. 1 shows the change in porosity of mushrooms. Porosity is the heat treatment temperature
There is a tendency to increase with the rise of. This is AlN
A large amount of Si and O in the polytypoid crystal grains
The porosity increases as it is discharged, and at the same time
AlN changed from the pressure is 1 atm N_TwoTranspiration in the atmosphere
It is believed that the temperature has risen
It is considered that this is the reason why the porosity increased. Also, SiO_Two
It seems that the amount of 27R will increase as the amount added increases.
Be done. For this reason, there are many plate crystals of 27R and
Since the porosity of the untreated sintered body is increased, Si
O_TwoThe porosity of the added amount of 15% by weight is higher than other samples.
It seems that it has become. Heat treatment temperature is 1900 ℃ and time
FIG. 2 shows the change in porosity when V is changed. Porosity
Increases immediately after heat treatment and then remains almost constant
Indicates. Again, SiO_TwoThe porosity of the addition amount of 15% by weight is
Higher, but SiO_TwoAs the amount added increases
Since the amount of 27R is also expected to increase, this porosity
It is considered to be larger than other samples.

[0018]SEM photograph SiO_TwoBefore the heat treatment in which the addition amount is changed by 5 to 15% by weight
Each sample and heat treatment time is 3 hours, and heat treatment temperature is 1
Fracture surface of each sample when changed to 900 or 2000 ℃
3 to 11 show SEM photographs of the above. The heat treatment is shown in FIGS.
The plate-like crystal of AlN polytypoid, which is a sample before
I can accept it. This plate crystal has a grain size of SiO 2._TwoAttendant
5 wt% (Fig. 3), 10 wt% (Fig. 4), 15 weight
It increases as the amount increases (Fig. 5). Next
In addition, as shown in FIGS.
By heat treatment at 0 ° C x 3h, AlN
Granular crystals of AlN, while leaving the shape of plate crystals of voids
Become. Further, as shown in FIGS.
At 000 ° C x 3 hours, these granular crystals grow and
It can be confirmed that the pores also grew. Crystal grains after heat treatment
It can be seen that the size of the is almost the same. these
As you can see from the SEM picture of AlN polytypoid
(Especially 27R) has a plate crystal, the first stage
When sintered as a floor, the plate crystals are entangled to some extent
A sintered body with a uniform pore distribution is formed.
Porosity by heat treatment at 1900-2000 ℃
A coherent aluminum nitride is formed. This is next
It becomes more apparent by the measurement of the pore size distribution of the term.

[0019]Pore size distribution Next, SiO_TwoThe amount added varies from 5, 10 and 15% by weight
Let it be the same composition as the sample before heat treatment and heat at 1900 ° C for 2 hours
The pore size distributions of the treated sample are shown in FIGS. 12 and 13, respectively.
Shown in. Look at the sample before heat treatment shown in FIG.
And SiO_TwoFor 10% and 15% by weight samples
It was confirmed that it had a bimodal peak
It This is because the pore size measured by mercury porosimetry is
Since it is determined by the diameter, it is surrounded by plate crystals and the entrance
With narrow pores, the value may be smaller than the actual pore diameter.
Expected, and I think it caused such a peak
Be seen. Next, heat treatment at 1900 ° C. for 2 hours shown in FIG.
The post-treatment sample has a monomodal peak.
As the grains grow, the pores also grow and the small pores disappear.
It is considered destroyed. In addition, SiO_Two5 added
Most frequent with increasing from 15% to 15% by weight
The high pore size of is gradually increasing. This is heat treatment
Pre-AlN polytypoid grains are SiO_Two5 weight added
%, 10% by weight, 15% by weight
Therefore, the pores are also made of SiO._TwoIncreased with the amount added
It is considered to be a thing.

[0020]Thermal conductivity SiO_TwoSample before heat treatment with addition amount of 5, 10, 15% by weight
And heat of the sample with the same composition after heat treatment at 1900 ° C for 2 hours
The conductivity is shown in FIG. Comparing the whole, heat treatment
The sample before heat treatment is 3 to 3.5 W / Km compared with the sample after heat treatment.
That is, the value is almost constant and low. For AlN sintered body
The heat-conducting carrier in the phonon (lattice vibration)
Strains, dislocations, lattice defects, and impurities that cause nonon scattering
The solid solution of the substance can be mentioned. AlN and SiO_TwoIs a solid solution of
AlN polytypoid is a long circumference with disordered stacking in the c-axis direction.
Structure, the symmetry of the crystal lattice is low,
As a result, the harmonics of lattice vibrations are scattered. Therefore, 27
The sample before heat treatment composed of R polytypoid is A
Low heat transfer compared to the heat-treated sample composed of 1N
I think that it shows the conductivity. At the same time with the sample before heat treatment
Is SiO_TwoAlthough the thermal conductivity becomes small as the amount added increases,
The amount of solid solution of Si and O was also increased.
It seems that For the sample after heat treatment, SiO_TwoAttendant
The thermal conductivity increases from 5 wt% to 10 wt%
But 10% to 15% by weight decreased
There is. In this, SiO_TwoAddition amount 10 to 15 weight
As for the decrease of thermal conductivity with respect to the amount%, the porosity is Si
O_TwoThe addition amount of 15% by weight was higher than that of 10% by weight.
It seems that

[0021]Permittivity 10% SiO adjusted in the same manner as above_TwoAbout the sample
hand,○○ DeviceHeat treatment (1900 ° C x 3 hours)
The dielectric constant before and after was measured. Care about these two samples
Table 3 shows the porosity, thermal conductivity and dielectric constant.

[Table 3] Since the sample is aluminum nitride after the heat treatment (Table 2), the thermal conductivity is 15 times or more that before the treatment. Since the porosity is as high as 48% and it is porous, the permittivity of aluminum nitride is 8 and the permittivity of air is 1. Therefore, it was predicted according to the compound rule that the permittivity was as low as 4.8. It was confirmed that aluminum nitride having

[0022]Example 2 The following experiment was conducted according to Example 1. Starting composition and
Then (R1) AlN-10 wt% SiO_Two-0.2 weight
% Y_TwoO_Three, (R2) AlN-10 wt% SiO_Two−
0.5% by weight Y_TwoO_Three, (R3) AlN-5 wt% Si
O_Two-0.5 wt% Y_TwoO_Three, (R4) AlN-10 fold
Amount% SiO_Two-1% by weight Y_TwoO_Three  Select 4 types of
A porous sintered body was produced by firing under the conditions. Silicon nitride
In a pot, 1900 ° C, 2 hours, 0.6 MPaN_TwoConditions
Was fired to prepare a polytypoid. The obtained sintered body
Put in a carbon crucible, 1900 ℃, 2 hours,
0.6 MPaN_TwoBy firing under the conditions of
Made Table 4 shows the characteristics of the obtained sintered body. This table
Is Y_TwoO_ThreePorosity can be controlled by adding
It is possible to change the thermal conductivity and the dielectric constant.
Which indicates that.

[Table 4] In the present invention, as the amount of SiO ₂ increases, other polytypoids such as 15R are produced. In this case, it is difficult to form homogeneous and excellent pores, but it was experimentally confirmed that the inclusion is allowed up to about 50% by volume.

[0023]

As described above, a porous aluminum nitride having such a high thermal conductivity and a low dielectric constant and a narrow pore size distribution has never been seen before. By utilizing such a property, the porous aluminum nitride of the present invention can be used for applications such as a substrate for a semiconductor device having a low dielectric constant and a filter material having excellent corrosion resistance.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between porosity and heat treatment temperature when an AlN polytypoid sintered body is heat treated for 3 hours.

FIG. 2 is a diagram showing the relationship between porosity and heat treatment time when an AlN polytypoid sintered body is heat treated at 1900 ° C.

FIG. 3 is a SEM photograph of a sample (5% SiO ₂ ) before heat treatment.

FIG. 4 is a SEM of a sample (SiO ₂ 10%) before heat treatment.
It is a photograph.

FIG. 5: SEM of sample (SiO ₂ 15%) before heat treatment
It is a photograph.

FIG. 6 shows a sample (Si that has been subjected to heat treatment (1900 ° C. × 3 hours).
It is an SEM photograph of O ₂ 5%).

FIG. 7: Sample (Si at 1900 ° C. × 3 hours) after heat treatment
It is a SEM photograph of O ₂ 10%).

FIG. 8: Sample (Si at 1900 ° C. × 3 hours) after heat treatment
It is a SEM photograph of O ₂ 15%).

FIG. 9: Sample (Si after heat treatment (2000 ° C. × 3 hours)
It is an SEM photograph of O ₂ 5%).

FIG. 10: Sample (S after heat treatment (2000 ° C. × 3 hours)
It is a SEM photograph of iO ₂ 10%).

FIG. 11: Sample (S after heat treatment (2000 ° C. × 3 hours)
It is a SEM photograph of iO ₂ 15%).

FIG. 12 is a diagram showing a pore size distribution of a sample before heat treatment.

FIG. 13 is a diagram showing a pore size distribution of a sample after heat treatment (1900 ° C. × 2 hours).

FIG. 14 is a diagram showing the thermal conductivity of a sample before and after heat treatment.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Junichi Tatami             30 Oromatsu-cho, Nishi-ku, Yokohama-shi, Kanagawa Prefecture             −401 (72) Inventor Masanori Abe             5-22-12 Tsunashima Nishi, Kohoku Ward, Yokohama City, Kanagawa Prefecture (72) Inventor Akihiko Tsuge             2-12-401 Wakaba-cho, Asahi-ku, Yokohama-shi, Kanagawa F-term (reference) 4G001 BA04 BA05 BA09 BA36 BB04                       BB05 BB09 BB36 BD38 BE33                       BE34                 4G019 FA13

Claims (8)

[Claims] 1. A porous aluminum nitride having a porosity of 5 to 60% and a pore size in the range of nano size to about 100 μm. 2. Porous aluminum nitride having a porosity of 5 to 60%, which is produced by heat treating an Al—Si—O—N-based AlN polytypoid in the presence of nitrogen and carbon. 3. 50% by weight of said AlN polytypoid
The porous aluminum nitride according to claim 2, wherein the above is 27R. 4. The temperature of the heat treatment is 1800 to 2050.
The porous aluminum nitride according to claim 2 or 3, which has a temperature of ° C. 5. The porous aluminum nitride according to claim 2, wherein the AlN polytypoid is produced by firing AlN and SiO ₂ . 6. SiO in an AlN—SiO ₂ mixed system
The porous aluminum nitride according to claim 5, wherein the ratio of ₂ is 30% by weight or less. 7. The porous aluminum nitride according to claim 5, wherein a rare earth oxide or an alkaline earth oxide is added as a sintering aid to the AlN polytypoid and fired. 8. The sintering aid is yttria, and the ratio of yttria to the AlN polytypoid is 1.
The porous aluminum nitride according to claim 7, which is 0% by weight or less.