JP3243214B2 - Aluminum nitride member with built-in metal member and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal member-containing aluminum nitride member and a method of manufacturing the same, and more particularly, to a metal member-containing aluminum nitride member effective as a base material of a semiconductor manufacturing apparatus such as an electrostatic chuck and a method of manufacturing the same. About the method.

[0002]

2. Description of the Related Art Pressure molding of ceramics by a hot press method is used for sintering various ceramics such as silicon nitride, silicon carbide and aluminum nitride.

Conventionally, for example, a ceramic member having a metal electrode such as an electrostatic chuck electrode embedded therein has been manufactured as follows. That is, as a ceramic substrate,
First, a ceramic powder such as dense aluminum nitride having thermal shock resistance so as not to be destroyed by a rapid temperature change is used, and is first preformed.

Next, the preform is manufactured by a uniaxial pressing method, and a metal such as molybdenum is buried in the preform in advance. Thereafter, the preformed body is hot-pressed so that pressure is applied in a direction substantially perpendicular to the metal electrode, and further, the sintered body is subjected to polishing or the like, so that the metal electrode is finally formed. A buried ceramic member was obtained.

[0005]

However, in the above-mentioned conventional method, since the ceramic powder is not SD granulated, the tap density is low, and the fluidity and deaeration of the powder during molding are poor. It is difficult to form a constant distance between the surface of the metal member and the metal electrode inside the ceramic member, and there is considerable variation in this distance.

Therefore, in the case of an electrostatic chuck or the like, there is a problem that the suction force of the semiconductor wafer on the suction surface varies, and in the case of a ceramic heater or the like, there is a problem that the surface temperature of the heater varies. .

Further, gas may be generated from the compact during firing under pressure by a hot press, and closed pores may be generated in the ceramic member. When this is polished, it may cause small holes. Furthermore, wrap as final processing,
Insufficient processing such as CMP causes particles to be generated in the semiconductor device to contaminate the semiconductor wafer, or the gas in the closed pores thermally expands at the time of sheath bonding for electrode terminal isolation in a later process. As a result, there is a problem that blisters, peeling, and shell-like cracks are generated in the ceramic member.

In view of such a problem, the present inventors are studying the development of the following manufacturing method when manufacturing a ceramic member in which a metal member such as a metal electrode is built.

That is, a mixture of a ceramic member material such as aluminum nitride and a binder is granulated by a spray granulator, and the obtained granules are compression-molded by a uniaxial pressure molding method to produce a preformed body. After that, a metal electrode such as molybdenum is placed inside the pre-formed body, and the granulated granules are further filled on the pre-formed body, and compression-molded again by the uniaxial pressure molding method to form a molded body in which the metal electrode is embedded. To manufacture.

Thereafter, the molded body is hot-pressed to obtain a sintered body, and the surface is polished to obtain a ceramic member having a metal member in which a metal member is built in aluminum nitride or the like. However, for example, when a ceramic member having a built-in metal member such as an electrostatic chuck is manufactured by such a manufacturing method, there is a problem that a change in volume resistance, discoloration, fluorine-based gas corrosion, contamination, particles, and appearance defects occur. there were.

[0011]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, it has been found that the above-mentioned change in volume resistance and decrease in insulation resistance are caused by metal members during the above-mentioned calcination and hot pressing. The molybdenum element contained therein reacts with the binder in the ceramic substrate such as aluminum nitride or the oxygen of the ceramic, and as shown in the following formula (1), it is found that the oxide is formed and diffused, The present invention has been made. 2Mo + 3O ₂ → 2MoO ₃ (1) That is, in an aluminum nitride member incorporating a metal member containing at least molybdenum, at least a surface of the metal member is used to prevent diffusion of molybdenum into aluminum nitride serving as a base material. An aluminum nitride member containing a metal member, which has a molybdenum-silicide phase, and a method for manufacturing the same.

According to the aluminum nitride member with a built-in metal member and the method of manufacturing the same according to the present invention, a molybdenum silicide phase is formed on at least the surface of the metal member. Since this phase has an effect of preventing molybdenum in the metal member from diffusing into the aluminum nitride substrate, the above-described oxide is not formed in the aluminum nitride substrate. Therefore, phenomena such as a change in volume resistance as described above can be significantly reduced. In the present invention, the molybdenum in the metal member does not necessarily indicate only the molybdenum element alone, but also includes molybdenum existing in a state of molybdenum oxide or the like.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments. The metal member that can be used in the present invention is preferably a flat metal bulk material from the viewpoint of performing hot press integral firing with ceramics. More specifically, from a flat metal bulk material, a flat metal bulk material such as an etching metal and a punching metal in which a large number of small spaces are formed, and a plate-like body having a large number of small holes. Metal bulk material, or a net-shaped metal bulk material.

Further, molybdenum is preferable because it can be integrally fired with aluminum nitride by hot pressing, has a high melting point, and has a thermal expansion close to that of the aluminum nitride. As the metal other than molybdenum, a high melting point metal stable at the firing temperature of aluminum nitride, for example, tantalum (Ta), tungsten (W), platinum (Pt), rhenium (Re), hafnium (Hf), and alloys thereof Etc. can be used.

In the present invention, a molybdenum-silicide phase is formed on at least the surface of the metal member to prevent molybdenum constituting at least a part of the metal member from diffusing into the aluminum nitride substrate. It is necessary. This molybdenum-silicide phase is very stable without causing decomposition or phase change even at high temperatures, and therefore has an excellent effect as a diffusion preventing layer.

As the molybdenum silicide phase, MoSi ₂ and Mo ₅ Si ₃ are preferable from the viewpoint of high-temperature stability.

The molybdenum-silicide phase can be formed by using, for example, a heat treatment method described in Japanese Patent Application Laid-Open No. 8-209327. That is, Cr
N is added to the Si alloy powder so that the Si content is 20% by weight.
A metal member containing at least molybdenum is buried in a H ₄ Cl, Al ₂ O ₃ powder, preferably in a mesh form, and is placed in a vacuum chamber, and a vacuum degree of 10
After exhausting to the order of ^-3 torr, the inside of the chamber is replaced with hydrogen gas (H ₂ ), a mixed gas of hydrogen and nitrogen (H ₂ -N ₂ ), or a mixed gas of hydrogen and helium (H ₂ -He). .

Then, at 1100 to 1200 ° C., 5 to 1
By heating for 0 hour, a molybdenum-silicide phase can be formed on at least the surface of the metal member.
Incidentally, Japanese Patent Publication No. 63-51356 and JP-A-8-2093.
No. 27 is for forming an antioxidant layer, and is completely different in technical idea from the present invention for forming a molybdenum silicide phase for preventing diffusion of molybdenum into an aluminum nitride substrate. It is.

Further, a molybdenum-silicide phase can be formed by SiH ₄ plasma thermal CVD or the like.

The molybdenum-silicide phase thus formed must be formed on at least the surface of the metal member as described above, and even if the entire metal member is formed of the molybdenum-silicide phase. good.

In order to effectively prevent the diffusion of molybdenum into the aluminum nitride substrate, the thickness of the molybdenum silicide phase is preferably 5 to 30 μm. Considering 5-20
μm is preferred.

The aluminum nitride member with a built-in metal member is manufactured by using the metal member obtained as described above, preferably as follows. The raw material of the aluminum nitride member and the binder are mixed in advance by a method such as trommel, and the obtained mixture is granulated by a spray granulator.

Next, the obtained granules are filled into a mold 1, a lower punch 2, and an upper punch 3 as shown in FIG. A molded body 4 is obtained.

Next, as shown in FIG.
A metal member 5 having a molybdenum / silicide phase on at least the surface is placed on the surface of the preform 4 described above, and the granulated granules 6 are further filled thereon.

Thereafter, as shown in FIG. 1C, a second preform 7 is newly formed on the first preform 4 and the metal member 5 by uniaxial pressure molding again. Then, an aluminum nitride member molded body with a built-in metal member made of the first preformed body, the metal member, and the second preformed body is manufactured.

Since the granules used in the present invention contain a binder in advance, the fluidity is extremely high and a uniform preform can be easily produced.

The first and second preforms 4,
7 preferably contains 0.4 to 5% by weight of a binder, more preferably 1 to 3% by weight. When the content of the binder is less than 0.4% by weight, the fluidity of the granulated granules becomes insufficient, the thickness of the preformed body becomes uneven, and the molding density tends to become uneven. Therefore, when the metal member is buried later, cracks, laminations, and the like easily enter the preformed body.

On the other hand, if the amount of the binder exceeds 5% by weight, the binder is less likely to be burned out during calcination and hot pressing. For this reason, when the metal member is buried in the preformed body later, the metal member is subjected to extreme carbonization and oxidation, and becomes brittle, or molybdenum is diffused. It is easy to occur.

As the binder that can be used in the present invention, a thermoplastic resin such as an acrylic binder and a butyral binder, or a thermosetting resin such as phenol can be used. It is preferable to use a thermoplastic resin such as an acrylic binder and a butyral binder because it is not thermally crosslinked during hot pressing and can be easily burned off at an initial relatively low temperature stage. further,
When used for semiconductor applications, sodium (Na),
A binder not containing an alkali metal such as potassium (K) is preferred.

The aluminum nitride member with a built-in metal member obtained as described above is placed in a calcining furnace, and is preferably placed in the air or in a mixed gas atmosphere of oxygen and nitrogen.
The binder is calcined at a temperature of 600 ° C. for 10 to 20 hours.

Next, the obtained calcined body was heated at a temperature of 1700 to 1700.
100-200kg at 2000 ℃ for 2-8 hours
/ Cm ² and hot pressing. The surface of the sintered body after hot pressing is polished to obtain an aluminum nitride member with a built-in metal member as a final form.

The above-described aluminum nitride member with a built-in metal member can be used in an active device such as an electrostatic chuck, a ceramic heater, or a high-frequency generation electrode by changing the shape, material and configuration of the metal member and the member. Although it can be used, it exhibits the most significant effect in electrostatic chucks, where molybdenum diffusion into the aluminum nitride substrate has the most effect on property degradation.

[0033]

The present invention will be described below in more detail with reference to examples. EXAMPLE As a metal member, a mesh electrode made of molybdenum having a small diameter of 0.12 mm, an outer diameter of 200 mm, and 50 mesh as shown in FIG. 2 was used.
The rSi alloy powder was buried in a powder obtained by mixing Al ₂ O ₃ powder and NH ₄ Cl powder, and was set in a vacuum chamber. After evacuating to a degree of vacuum of 10 ⁻³ torr, the inside of the chamber was replaced with hydrogen gas and heated at 1100 ° C. for 10 hours. After the heat treatment, the molybdenum mesh electrode
When examined by X-ray diffraction (XRD),
It was found that a molybdenum silicide phase composed of MoSi ₂ and Mo ₅ Si ₃ was formed. Further, when examined by a scanning electron microscope (SEM), the thickness of the molybdenum silicide phase was about 20 μm. there were.

Next, aluminum nitride powder (average particle size: 70 μm) was used as a ceramic base material (deleted), and an acrylic resin binder (n-butyl methacrylate) was added thereto by 1% by weight. These mixtures were produced. Subsequently, the mixture was granulated by a spray granulator (spray dryer). These granulated granules and molybdenum reticulated electrodes were molded as shown in FIG. 1 described above, and had a diameter of 215 mm and a thickness of 30 mm.
mm was obtained.

The thickness t ₁ of the _first preform and the second thickness t ₁
The ratio of the thickness t ₂ of the preform, 1: 4 and then, further, the molding density of the first and second preform is 1.6 g /
It was the cm ^3. This was placed in a calciner and replaced with the atmosphere, and then heat-treated at 450 ° C. for 20 hours to perform calcining.
When the temperature reached 20 ° C., it was taken out of the furnace, and the calcined body was heated at a temperature of 1900 ° C. for 8 hours to 200 kg / cm ^2.
And hot pressing was performed.

The obtained sintered body is subjected to a polishing treatment,
An aluminum nitride member having a molybdenum mesh electrode in the final form was obtained. Similarly, the heating temperature and the heating time were changed as shown in Table 1, the thickness of the molybdenum silicide layer was changed in the range of 2 to 30 μm, and further, as described above, granulation and hot pressing were performed. ,
An aluminum nitride member having a built-in molybdenum mesh electrode was obtained.

[0037]

[Table 1]

Here, the color tone shown in Table 1 was visually confirmed after firing, after polishing the mesh surface side with diamond abrasive grains to # 400, making the mesh surface thickness 0.4 ± 0.1 mm.
The small holes were wrapped with diamond abrasive grains after color tone inspection, polished with colloidal SiO ₂ , and then visually confirmed. The volume resistance was measured by an underwater method by opening a hole of φ5 mm from the surface opposite to the mesh to the mesh surface. The corrosiveness due to ClF ₃ gas was as follows.
Cut out to 0x3tmm, 100% concentration, pressure 200t
The test was performed by exposing to a ClF ₃ gas at 400 ° C. orr for 1 hour.

As is clear from Table 1, when the thickness of the molybdenum silicide layer is 30 μm, the color tone slightly deteriorates. However, according to the present invention, the molybdenum silicide layer is formed on at least the surface of the metal member. It can be seen that, by forming, a good appearance characteristic is exhibited, there is no corrosion by the fluorine-based gas, and further, the volume resistance is almost constant.

A portion in which the molybdenum mesh electrode was buried was cut out from the aluminum nitride member, and a cross section was observed. FIGS. 3 to 6 show composition maps of molybdenum, oxygen, aluminum, and nitrogen by EPMA in a cross section of an aluminum nitride member having a molybdenum silicide phase thickness of 20 μm. In these figures, the reddish map indicates that the concentration of the target substance is higher, and conversely, the map is bluer and darker, indicating that the concentration of the substance is lower.

Comparative Example An aluminum nitride member having a built-in molybdenum reticulated electrode was manufactured in the same manner as in Example except that the molybdenum-silicide phase was not formed on the surface of the molybdenum reticulated electrode. Molybdenum, oxygen, aluminum, by EPMA in the cross section of this aluminum nitride member,
7 and 10 show composition maps of nitrogen and nitrogen. As in the case of the embodiment, the red portion of the map indicates a portion where the concentration of the target substance is high, and the reverse, blue and dark portion indicates that the concentration of the substance is low. ing.

As is clear from the composition maps of the examples and the comparative examples by EPMA, FIG. 7 shows a comparative example in which a molybdenum-silicide phase was not formed on the surface of a reticulated electrode made of molybdenum as a metal member. Thus, it is understood that molybdenum extends to the outside of the molybdenum mesh electrode, and further, as shown in FIG. 8, oxygen is present in proportion to the region where the molybdenum extends.

Accordingly, it can be seen that the molybdenum and oxygen chemically bond with the oxygen in the binder and the oxygen in the aluminum nitride to form molybdenum oxide.
This is clear from the composition maps of aluminum and nitrogen in FIGS. 9 and 10. That is, the concentration of aluminum and nitrogen in the region where molybdenum extends outside the electrode is reduced, which clearly indicates a reduction in the aluminum nitride as the ceramic base material. That is, it is easily determined that the molybdenum oxide diffuses into the aluminum nitride and reduces its composition concentration.

On the other hand, in the embodiment of the present invention in which a molybdenum silicide phase is formed on the surface of a molybdenum mesh electrode, as shown in FIG. 3, the manner in which molybdenum extends outside the molybdenum mesh electrode is as follows. can not see. Further, as shown in FIG. 4, oxygen is also uniformly dispersed almost all over the triple point of the aluminum nitride crystal, and it is not seen that molybdenum and oxygen combine to form an oxide. .

Similarly, the concentration distributions of aluminum and nitrogen around the electrode are almost uniform, and there is no decrease in the amount of aluminum nitride as the ceramic substrate as in the comparative example. Therefore, according to the present invention, since molybdenum does not diffuse into the aluminum nitride base material to form an oxide, even when such an aluminum nitride member is used for an electrostatic chuck, a heater, or the like, the volume does not increase. No change in resistance, discoloration, fluorine gas corrosion, contamination, particles, etc. are generated.

[0046]

As described above, according to the aluminum nitride member with a built-in metal member and the manufacturing method of the present invention, a molybdenum-silicide phase is formed on at least the surface of a metal member containing molybdenum. When an aluminum nitride member is formed by using, the diffusion of molybdenum into the aluminum nitride substrate can be effectively prevented.

Therefore, even when an active device such as an electrostatic chuck is formed of the aluminum nitride member containing the metal member, there is no change in volume resistance, discoloration, fluorine-based gas corrosion, contamination, particles and appearance defects. A device can be obtained. Further, unlike the conventional aluminum nitride member incorporating the metal member of the present invention, granulated granules are produced from a mixture of a ceramic base material and a binder in advance, and further calcined before hot pressing. Therefore, the distance between the surface of the aluminum nitride member and the metal member inside the aluminum nitride member can be made constant.

In addition, pores may be formed in the aluminum nitride member after hot press sintering, or particles may be generated during polishing to damage the surface, or the pores may be thermally expanded. Thereby, the problem of generating minute cracks in the aluminum nitride member can also be solved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a molding process of the present invention.

FIG. 2 is a diagram showing a molybdenum mesh electrode according to an embodiment of the present invention.

FIG. 3 is a composition map of molybdenum by EPMA of a cross section of an aluminum nitride member containing a metal member in an example of the present invention.

FIG. 4 is an oxygen composition map by EPMA of a cross section of an aluminum nitride member having a built-in metal member in an example of the present invention.

FIG. 5 is an aluminum composition map by EPMA of a cross section of an aluminum nitride member having a built-in metal member in an example of the present invention.

FIG. 6 is a nitrogen composition map by EPMA of a cross section of an aluminum nitride member incorporating a metal member in an example of the present invention.

FIG. 7 is a composition map of molybdenum by EPMA of a cross section of an aluminum nitride member containing a metal member in a comparative example of the present invention.

FIG. 8 is a map of oxygen composition by EPMA of a cross section of an aluminum nitride member incorporating a metal member in a comparative example of the present invention.

FIG. 9 is a composition map of aluminum by EPMA of a cross section of an aluminum nitride member containing a metal member in a comparative example of the present invention.

FIG. 10 is a nitrogen composition map by EPMA of a cross section of an aluminum nitride member incorporating a metal member in a comparative example of the present invention.

[Explanation of symbols]

Reference Signs List 1 mold 2 lower punch 3 upper punch 4 first preformed body 5 metal member 6 granulated granule 7 second preformed body A, A 'Molybdenum mesh electrode cross section

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-217548 (JP, A) JP-A-7-273164 (JP, A) JP-B-63-51356 (JP, B1) (58) Field (Int.Cl. ⁷ , DB name) C04B 35/581-35/582 C04B 35/74 H01L 21/68 H05B 3/18

Claims (5)

(57) [Claims] An aluminum nitride member containing a metal member containing at least molybdenum, wherein at least a surface of the metal member has a molybdenum-silicide phase for preventing diffusion of molybdenum into aluminum nitride serving as a base material. An aluminum nitride member with a built-in metal member, comprising: 2. The molybdenum silicide phase is MoS
_{2. The} aluminum nitride member with a built-in metal member according to claim 1, comprising at least one of i ₂ and Mo ₅ Si _{3. 3} . 3. The thickness of the molybdenum silicide phase is:
The aluminum nitride member with a built-in metal member according to claim 1, wherein the thickness is 5 to 30 μm. 4. A first preform is manufactured by subjecting a mixture of a raw material of an aluminum nitride member and a binder to granulation by a spray granulator, and subjecting the obtained granules to uniaxial pressure molding. At least on the surface, a metal member having a molybdenum-silicide phase for preventing diffusion of molybdenum into aluminum nitride serving as a base material is provided on the first preform, and the metal member and the first After placing the granules on the preform and performing uniaxial pressure molding again to produce an aluminum nitride member molded body incorporating the metal member, calcining the molded body, and then hot pressing. A method for producing an aluminum nitride member with a built-in metal member. 5. The method according to claim 1, wherein the molybdenum silicide phase is MoS
wherein the of i ₂ and Mo ₅ Si ₃ is at least one, producing a metallic component built aluminum nitride member according to claim 4.