JP2001240474A - Plasma resistant member, method of manufacturing the same, and plasma apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma proof member, its manufacturing method and a plasma device excellent in an anti-corrosion property against the plasma and having high thermal conductivity. SOLUTION: This plasma proof member is of an Aluminum nitride sintered body mainly composed of aluminum nitride crystal phase. On a grain boundary of the phase, a grain boundary phase containing at least group 3a elements of the periodic table, Al, B, O, and N is present. The heat conductivity of the sintered body is higher than 160 W/mK at room temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma-resistant member which can be suitably used for parts of a plasma apparatus exposed to a plasma atmosphere, a method for manufacturing the same, a device manufacturing process for semiconductors and liquid crystals, a micromachine manufacturing process, The present invention relates to a plasma device suitably used in a manufacturing process involving an electronic circuit manufacturing process, a thin film manufacturing process, and other etching processes.

[0002]

2. Description of the Related Art At present, a plasma apparatus is used for manufacturing devices such as semiconductors and liquid crystals, for manufacturing micromachines formed by etching, for manufacturing electronic circuits for forming wiring boards, and for thin films such as sputtering and plasma CVD. Plasma devices are used in a wide range of manufacturing steps, such as manufacturing steps and other steps involving etching.

[0003] A plasma device is a device for ionizing a part of a specific gas to form a gas composed of electrons, ions and neutral particles, and includes a vacuum vessel, a gas introducing device and a plasma generating device. And a fixing jig for holding an object to be processed. Specifically, a nuclear fusion device, a thin film forming device such as plasma CVD, sputtering or ion plating, RIE (reactive ion etching), An etcher such as a density ion etching apparatus may be used.

[0004] A plasma generator is a device for forming an electromagnetic field by direct current, alternating current, high frequency or the like to ionize gas, and particularly using a high frequency of 0.8 to 13.56 MHz or a microwave of 2.45 GHz. It has a power supply and electrodes for forming plasma.

In particular, in an etching apparatus used in a plasma semiconductor manufacturing process or a manufacturing process accompanied by another etching process, a high frequency is applied to a gas in the device to a flat electrode or a coil-like induction electrode to generate plasma. The surface of an object to be processed is etched in a plasma atmosphere of a corrosive gas.

[0006] Therefore, in these plasma devices, particularly the members inside the device are severely corroded, which affects the yield, product cost and product reliability. Therefore, members used in the plasma apparatus are required to have corrosion resistance to plasma, and silicon carbide, carbon members, or alumina materials have been used.

In recent years, aluminum nitride sintered bodies have many excellent properties such as high thermal conductivity, heat resistance, corrosion resistance, electrical insulation, and piezoelectricity. Applications are being promoted as functional materials. Particularly, it has been studied as a member for a semiconductor manufacturing apparatus, and it is disclosed in, for example, Japanese Patent No. 2862779 that an aluminum nitride sintered body has good corrosion resistance to a plasma atmosphere caused by a halogen-based corrosive gas.

Further, regarding the high thermal conductivity of aluminum nitride, a material system in which boron nitride is added to aluminum nitride is described in, for example, Japanese Patent Application Laid-Open No. 3-252267, wherein 40 to 5% by weight of hexagonal boron nitride is used. By adding it, the bending strength could be improved simultaneously with the heat conduction.

On the other hand, a method for producing aluminum nitride is described in, for example, Japanese Patent Application Laid-Open No. 8-259330.
10-70% by weight of boron carbide (B ₄ C), 30~90 wt% of aluminum (Al), material production method of containing boron nitride from a mixture powder containing 10 to 60 wt% of silicon (Si) It is shown.

[0010]

However, recently,
For example, plasma used in a semiconductor manufacturing apparatus tends to have a higher density and a higher calorific value, so that corrosion resistance to plasma has been further required.

However, aluminum nitride described in Japanese Patent Application Laid-Open No. 3-25267 has a problem that corrosion resistance is not sufficient, and particularly, a member having a large temperature rise has a problem that corrosion to plasma is large.

In Japanese Patent Application Laid-Open No. 8-259330, the effect of adding B ₄ C to aluminum nitride is intended only for corrosion resistance to molten metal and slag.
There is no description about the corrosion resistance in the plasma atmosphere, and it was unknown. In addition, since the content of B ₄ C is large, the dielectric loss is large, and the thermal conductivity is much lower than that of aluminum nitride. .

Accordingly, it is an object of the present invention to provide a plasma-resistant member having excellent corrosion resistance to plasma and high thermal conductivity, a method for manufacturing the same, and a plasma apparatus.

[0014]

The present invention provides, as an aluminum nitride sintered body, a grain boundary phase comprising a Group 3a element of the periodic table, aluminum, boron, oxygen and nitrogen,
Further, it is based on the finding that plasma resistance can be significantly improved by keeping the member temperature low.

That is, the plasma-resistant member of the present invention has an aluminum nitride crystal phase as a main component, and contains at least a Group 3a element of the periodic table, aluminum, boron, oxygen and nitrogen at the grain boundaries of the aluminum nitride crystal phase. It is characterized by comprising an aluminum nitride sintered body having a grain boundary phase and having a thermal conductivity of 160 W / mK or more at room temperature.

As described above, by containing at least a Group 3a element of the periodic table, aluminum, boron, oxygen and nitrogen as a grain boundary phase, corrosion resistance is increased, and by setting the thermal conductivity to 160 W / mK or more, The plasma resistance is improved by a synergistic effect obtained by increasing the cooling efficiency of the member and suppressing a decrease in the corrosion resistance due to a high temperature of the member.

In particular, the amount of boron in the aluminum nitride sintered body is preferably 0.01 to 3% by weight. This has the effect of increasing the thermal conductivity. 3% by weight
If the temperature exceeds the range, the thermal conductivity tends to decrease, and the dielectric loss tends to increase. The microwave absorbs heat to generate heat, and the plasma resistance may decrease.

It is preferable that the element of Group 3a of the periodic table in the aluminum nitride sintered body is 0.01 to 3 mol% in terms of oxide relative to aluminum nitride.
Thereby, sinterability can be improved while maintaining high thermal conductivity.

The method for producing a plasma-resistant member of the present invention comprises aluminum nitride as a main component, and an oxide of a Group 3a element in the periodic table with respect to the aluminum nitride.
A molded article containing 3 mol% and 0.01 to 3% by weight of B ₄ C in the total amount in terms of B amount was placed in an inert atmosphere at 150%.
It is characterized by firing at 0 ° C to 2000 ° C. By this method, a grain boundary phase containing at least a Group 3a element of the periodic table, aluminum, boron, oxygen, and nitrogen can be formed, and the thermal conductivity at room temperature can be 160 W / mK or more.

Further, the plasma apparatus of the present invention is a plasma apparatus including at least a vacuum vessel, a gas introduction device, a plasma generation device, and a fixing jig for holding an object to be processed. The plasma-resistant member of the present invention is used as a member that comes into contact with plasma in a vacuum vessel. This makes it possible to realize a plasma apparatus capable of producing a product with a long life of members, high productivity, and high reliability.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The plasma-resistant member of the present invention mainly comprises an aluminum nitride crystal phase, and at least a group 3a element of the periodic table, aluminum, boron, oxygen and nitrogen are present at the grain boundaries of the aluminum nitride crystal phase. It is important that a contained grain boundary phase exists, and it is necessary that the thermal conductivity of the plasma-resistant member at room temperature be 160 W / mK or more.

The aluminum nitride crystal phase has a sintered body of 16
There is no problem as long as it has a thermal conductivity of 0 W / mK, but in particular, the average particle size of the crystal particles is 1 to 50 μm, particularly 5 to 30 μm.
m, more preferably 10 to 20 μm, in order to obtain a high thermal conductivity.

Although a grain boundary phase exists at the grain boundaries of the aluminum nitride crystal phase, according to the present invention, RE-Al-B-
It is important to form a grain boundary phase formed by ON. That is, the group 3a element of the periodic table promotes densification, and boron significantly suppresses the thermal conductivity of the aluminum nitride sintered body and the plasma resistance of the grain boundary phase, so that generation of particles can be suppressed. .

The grain boundary phase of the aluminum nitride crystal phase depends on the amount of the element belonging to Group 3a of the periodic table.
Al-B-ON (RE: Periodic table 3a such as Y, Er, etc.)
, A compound comprising at least two elements of Group 3a elements (RE), aluminum (Al), boron (B), oxygen (O) and nitrogen (N) of the periodic table It is desirable to contain the crystal phase of. Note that an amorphous phase containing Si, Al, and oxygen may be present in the sintered body.

For example, a so-called garnet type oxide, which is a composite oxide of an oxide of an element of Group 3a of the Periodic Table represented by the general chemical formula Al ₅ Y ₃ O ₁₂ (Y: an element of Group 3a of the Periodic Table) and alumina. Crystal phase and perovskite type crystal phase (AlYO
₃ ) and monoclinic type crystal phase (Al ₂ Y ₄ O ₉ ).

The Group 3a element of the periodic table has a role as a sintering aid and a function to absorb oxygen in the aluminum nitride crystal to increase the thermal conductivity. And when the content is in the range of 0.01 to 3 mol% with respect to aluminum nitride, the above-mentioned effect becomes remarkable, which is preferable.

It is preferable that boron is in a solid solution in the grain boundary crystal phase, for example, and that B ₄ C does not exist. As the content of boron increases, B ₄ C gradually remains. If the amount of boron exceeds 10% by weight of the total amount, B ₄ C tends to remain,
In some cases, heat is absorbed by absorbing high frequencies, and the plasma resistance is reduced. If the amount is 0.01% by weight or less, the thermal conductivity and the plasma resistance tend to be small. Therefore, the amount of boron is 0.01 to 3% by weight, particularly 0.05 to
2% by weight, more preferably 0.1 to 1.5% by weight.

The thermal conductivity of the aluminum nitride sintered body is 1
It is important that it is 60 W / mK or more. In particular, 18
It is preferably 0 W / mK or more, more preferably 200 W / mK. By increasing the thermal conductivity, the cooling efficiency of the member can be increased, and the effect of keeping the member temperature low by removing heat generated by high frequency absorption and heat obtained from the plasma is great.

The relative density of the sintered body is 97% or more, especially 98%
%, More preferably 99% or more, more preferably 99.5% or more. As a result, the strength of the member can be increased, and an improvement in plasma resistance due to the reduced surface area can be expected.

In the plasma-resistant member of the present invention having the above-described structure, boron is added to the grain boundary phase to improve the plasma resistance of the grain boundary phase and to reduce the thermal conductivity of the aluminum nitride sintered body. Since the cooling is remarkably improved and the cooling can be performed efficiently, the temperature of the member is increased at or near the portion in contact with the plasma, so that the progress of corrosion can be suppressed.

Further, the plasma apparatus of the present invention includes, for example, the plasma apparatus 1 shown in FIG. 1 and includes at least a vacuum vessel 2, a gas introduction device, a plasma generation device, and a fixing jig 7 for holding an object to be processed. The plasma apparatus 1 is characterized in that the plasma-resistant member 8 of the present invention is used as a member that comes into contact with plasma in the vacuum vessel 2 of the plasma apparatus 1.
In this case, the plasma-resistant member 8 is applied to the wall surface of the plasma device 1 and is exposed to the plasma because the plasma is generated inside.

The member that comes into contact with the plasma refers to a member that undergoes corrosion due to the influence of ions and active species in the plasma, and in particular, a member disposed inside the plasma, a container that encloses the plasma, or a member that contacts the plasma. It is a member or the like in which there is no object to be intercepted.

The vacuum vessel 2 is separated from the atmosphere and allows the inside of the vessel to be reduced in pressure to less than 1 atm.
In particular, the degree of vacuum is preferably 100 Pa or less, more preferably 1 Pa or less in consideration of the influence of residual gas. For this purpose, it is necessary to exhaust the atmosphere from the exhaust port 4 using a vacuum pump for evacuating to achieve a vacuum state, and to keep the pressure inside the container constant by exhausting gas. You can do it.

The gas introducing device is a facility for introducing at least a desired gas into the vacuum vessel 2. Generally, a gas at a predetermined flow rate is supplied from a gas supply facility such as a gas cylinder into the vacuum vessel 2. This is equipment to be introduced, and the gas flow rate is usually adjusted by a mass flow controller or the like.

Further, a plasma generator is equipment for forming an electric field required for generating plasma.
Particularly, a high-frequency generator of 1 MHz to 10 GHz, particularly 0.4 to 5 GHz, and even 0.7 to 2.6 GHz, and a wiring or a waveguide for guiding the generated high frequency to an electrode or a device.

The fixing jig 7 for the object to be processed is
In order to perform processing such as etching and film formation on an object to be processed such as the wafer 6, the wafer 6 is fixed at a predetermined position, and a susceptor or an electrostatic chuck can be used. When the degree of vacuum in the vacuum device 2 is low, a vacuum chuck may be used.

The plasma apparatus thus configured uses the plasma-resistant member of the present invention, and extends the life of the member exposed to a severe environment and prolongs the time until the replacement of the part, thereby replacing the member. In addition to reducing the number of stoppages of the apparatus at the same time, the throughput can be increased, and the cost for members can be saved, and as a result, the cost can be greatly reduced. Further, since contamination of impurities into plasma can be reduced, stable processing can be performed.

Next, a method for manufacturing the plasma-resistant member of the present invention will be described.

First, the method of producing the aluminum nitride raw material powder is not limited, but those produced by a direct nitriding method, a reduction nitriding method, a CVD method or the like can be suitably used. In general, the thermal conductivity tends to increase as the amount of oxygen contained in the aluminum nitride particles decreases, but 2% or less, particularly 1%, as an inevitable impurity in the raw material.
% Or less of oxygen, carbon and the like may be present.

The particle size of the aluminum nitride raw material powder is not limited. However, the average particle size of the aluminum nitride raw material is 3 μm or less because the particle size of the aluminum nitride raw material is generally small and uniform as the sinterability is good. In particular, 1 μm or less is desirable.

If necessary, the purity of the aluminum nitride raw material powder is 99% or more, and preferably, the average particle size is 3.0.
μm or less, particularly 1.0 μm or less, which promotes densification of the sintered body and has an excellent plasma resistance, which is an oxide of a Group 3a element of the periodic table, particularly Y ₂ O ₃ , Er ₂ O ₃ , L
a ₂ O _3, is added as _{CeO 2, Lu 2 O 3,} Dy 2 O 3, Yb 2 O sintering aids oxides of the Periodic Table Group 3a elements, such as _3.

The oxide of the Group 3a element of the periodic table lowers the thermal conductivity if added in too large an amount, so that the content is preferably 2 mol% or less, particularly preferably 1 mol% or less.

It is necessary to add B ₄ C as a boron source. B compounds other than B ₄ C, such as BN and B ₂
In the case of O ₃ or the like, not only does the sinterability significantly deteriorate, but also a material having high thermal conductivity cannot be obtained even in a dense body. It is considered that the cause is that B compounds other than B ₄ C remain during sintering or form BN, which inhibits grain growth by remaining at grain boundaries. Further, since BN has low plasma resistance, it lowers the plasma resistance of the aluminum nitride sintered body.

On the other hand, when B ₄ C is added, it reacts with the grain boundary phase during sintering and forms a solid solution in the grain boundary phase without forming BN. It is considered that the plasma properties are improved.

Although there is no particular limitation on the B ₄ C raw material powder, if it is a generally used powder, for example, the purity of boron carbide is 95% or more, preferably 99% or more, 3 μm or less in diameter, preferably 1 μm
m or less. If the purity of B ₄ C is low, the thermal conductivity is reduced by impurities, and if the particle size is large, solid solution to the grain boundary phase does not proceed, and boron carbide may remain to increase the dielectric loss. In addition, it hinders sintering of aluminum nitride and makes it difficult to obtain a dense body.

Therefore, the amount of B ₄ C added is preferably 0.01 to 3% by weight, particularly 0.05 to 2% by weight, more preferably 0.1 to 1.5% by weight in terms of the amount of B. . When the added amount of B ₄ C is in the above range, the thermal conductivity is remarkably improved, the B ₄ C particles are less retained, the dielectric loss can be suppressed, and as a result, the plasma resistance can be increased. it can.

Further, if desired, an organic binder such as an acrylic, butyral, or alcohol-based solvent, a solvent, or the like is added, and the mixture is mixed by a known mixing method such as a ball mill or a vibration mill.

Next, the obtained mixed powder or slurry is molded into a predetermined shape by a known molding method such as a uniaxial pressing method, a casting method, an extrusion molding method, a doctor blade method and the like. In order to improve the sinterability of the aluminum nitride powder at the time of firing and to make the sintered body denser, the pressing pressure is 80 MPa.
It is preferable to perform cold isostatic press molding at a pressure of 200 MPa or more after forming, or at least 100 MPa or more.

In the firing, the firing method is not particularly limited, and examples thereof include ordinary resistance heating, hot pressing, HIP, and microwave firing. It is necessary to use an inert atmosphere (including a vacuum atmosphere) in order to prevent the decomposition and oxidation of AlN as the atmosphere at the time of firing, and it is preferable to use a nitrogen gas atmosphere.

Further, the firing temperature is from 1500 ° C. to 2000
It is important that the temperature is in the range of 1600 ° C. to 1800 ° C. If the temperature is less than 1500 ° C., a dense body tends to be difficult to obtain, or a long time is required for firing, and the cost may increase to obtain a desired thermal conductivity. Moreover, if the temperature is higher than 2000 ° C., the furnace which can be heated is limited, which leads to an increase in firing cost.

Although the firing time is not particularly limited,
Generally, it is desirable to bake for 5 minutes to 3 hours.

[0052]

EXAMPLE An aluminum nitride raw material having a purity of 99% and having an average particle diameter of 1.5 μm prepared by a reduction nitriding method was prepared, and an oxide of an element of Group 3a of the periodic table shown in Table 1 was used as a sintering aid. 0.5 to 3 mol% was added. Here, the aluminum nitride and the oxide of the Group 3a element in the periodic table
The raw materials were prepared by mol%.

Next, BN or B ₄ C was added as a boron source in an amount shown in Table 1. The boron source was added as a percentage by weight in the total amount.

These mixed powders were ball-milled for 20 hours using IPA (isopropyl alcohol) as a solvent and wet-mixed. After drying the obtained mixed powder, a molding pressure of 45
After forming a compact of φ20 × 10 t by uniaxial pressing of MPa, the compact was subjected to a cold isostatic pressing (CIP) of 200 MPa.

Then, the obtained compact was placed in an electric resistance furnace, and was heated to 1700 ° C. to 1900
The firing was performed at a temperature of 3 ° C. for 3 hours. With respect to the obtained sample, the relative density, which is a ratio to the theoretical density, was measured by the Archimedes method, and the sample having a relative density of 95% or more was evaluated.

The thermal conductivity of the obtained sintered body was measured by a laser flash method. The presence of B in the grain boundary phase was determined by EELS attached to a TEM (transmission electron microscope).
(Electron energy loss spectroscopy) was used to confirm whether segregation occurred in the grain boundary phase. Further, the amount of B in the sintered body is
After grinding the sample, it was performed by an ICP emission spectrometer.
In order to evaluate the corrosion resistance to plasma, each sintered body was placed in a reactive ion etching apparatus, and a mixed gas of CF ₄ , CHF ₃ and Ar (gas 1),
Alternatively, SF ₆ gas (gas 2) is introduced to reduce the pressure in the apparatus to 7
-10 MPa. And 13.56 MHz,
Plasma was generated by introducing a high frequency of 1 kW, and the sample was brought into contact with the plasma. Under the above conditions, the etching treatment was performed for 3 hours, and the etching rate was calculated from the weight loss of the sample. The results are shown in Table 1.

[0057]

[Table 1]

In the sample No. of the present invention, 3 to 10 and 12 to
In No. 19, the etching rate was 29 ° / min or less for gas 1 and 38 ° / min or less for gas 2.

On the other hand, Sample No. which was not added with boron and which was outside the scope of the present invention. In Examples 1 and 2, the thermal conductivity was as low as 135 W / mK, and the etching rate was 40 ° / min or more for gas 1 and 56 ° / min or more for gas 2.

Further, the content of boron exceeds 3%, the thermal conductivity is as small as 134 W / mK, and the sample N out of the range of the present invention.
o. 11 is 48 ° / mi when the etching rate is gas 1
In the case of n and gas 2, it was 66 ° / min.

Further, Sample No. which is outside the scope of the present invention and in which BN is added as a boron source. 20-No. In Sample No. 24, not only densification was hindered, but also the thermal conductivity was reduced. As a result, the etching rate was 42 ° / min or more for gas 1 and 58 ° / min or more for gas 2.

[0062]

According to the present invention, the thermal conductivity of an aluminum nitride sintered body is increased by arranging a crystal phase composed of RE-Al-B-O-N at a grain boundary of an aluminum nitride crystal phase. In addition, a plasma-resistant member having excellent corrosion resistance to plasma using a halogen-based corrosive gas such as CF ₄ or ClF ₃ can be provided in order to enhance the plasma resistance of the grain boundary phase.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a plasma device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Plasma apparatus 2 ... Vacuum container 3 ... Gas inlet 4 ... Exhaust port 5 ... High frequency induction electrode 6 ... Wafer 7 ... Fixing jig 8 ... Resistance Plasma components

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05H 1/46 C04B 35/58 104B // G21B 1/00 H01L 21/302 BF Term (Reference) 4G001 BA08 BA09 BA11 BA23 BA36 BA63 BB08 BB09 BB11 BB23 BB36 BB63 BB67 BC13 BC52 BD03 BE11 4K030 FA01 KA46 5F004 AA15 AA16 BA20 BB13 BB14 BB29 BC08 BD04 5F045 AA08 BB14 EB03 EC05 EH11 EH12

Claims (5)

[Claims] An aluminum nitride crystal phase is mainly contained, and a grain boundary phase containing at least a Group 3a element of the periodic table, aluminum, boron, oxygen and nitrogen is present at a grain boundary of the aluminum nitride crystal phase. Has a thermal conductivity of 160
A plasma-resistant member comprising an aluminum nitride sintered body having W / mK or more. 2. The plasma-resistant member according to claim 1, wherein the amount of boron in the aluminum nitride sintered body is 0.01 to 3% by weight. 3. The aluminum nitride sintered body according to claim 1, wherein the element of Group 3a of the periodic table is 0.01 to 3 mol% as oxide relative to aluminum nitride. 2. The plasma-resistant member according to 2. 4. An aluminum nitride as a main component, 0.01 to 3 mol% of an oxide of a Group 3a element in the periodic table with respect to the aluminum nitride, and B ₄ C in the total amount of 0.1 to 3 mol%.
A method for producing a plasma-resistant member, comprising firing a compact containing from 01 to 3% by weight in an inert atmosphere at 1500 to 2000 ° C. 5. A plasma device comprising at least a vacuum container, a gas introducing device, a plasma generating device, and a fixing jig for holding an object to be processed, wherein the plasma device is in contact with plasma in a vacuum container of the plasma device. Claims 1 to 3 as members
A plasma apparatus characterized by using any one of the plasma-resistant members described above.