JPH10330150A - Corrosion resistant member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a corrosion resistant member having an excellent corrosion resistance against plasma in an atmosphere containing a halogen-based corrosive gas such as a fluorine-based or chlorine-based gas. SOLUTION: This corrosion resistant member is composed of a ceramic sintered compact comprising >=15 wt.% MgO and <=85 wt.% Al2 O3 , in terms of oxides, having any crystal phase of MgO, MgAl2 O4 and MgO, MgAl2 O4 , and MgAl2 O4 and Al2 O3 , further having >=3 μm average crystalline particle diameter of the crystal phase and having <=0.2% porosity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention provides a corrosion-resistant member having excellent corrosion resistance to plasma in an atmosphere in which a halogen-based corrosive gas is present.
For example, it can be suitably used as a jig such as a wafer holder or a clamp ring or an inner wall material used for a plasma apparatus for semiconductor production or a liquid crystal process, or a CFC gas decomposition processing apparatus or a laser tube of an excimer laser. .

[0002]

2. Description of the Related Art Conventionally, as a plasma process in a semiconductor device manufacturing process, a halogen-based corrosive gas such as a fluorine-based gas and a chlorine-based gas has been used for vapor phase growth, etching and cleaning due to its high reactivity. I have.

[0003] Since the members exposed to plasma under these halogen-based corrosive gases are required to have corrosion resistance, quartz glass, corrosion-resistant light metal materials such as stainless steel and aluminum, and alumina sintered bodies and Aluminum nitride sintered bodies and those obtained by coating these ceramic sintered bodies with a ceramic film such as silicon carbide have been used (Japanese Patent Publication No. 5-53872, JP-A-3-217016).
And JP-A-8-91932. )

[0004]

However, in the case where quartz glass is used as the corrosion-resistant member, the corrosion resistance in the plasma is insufficient, so that when exposed to halogen plasma, the contact portion with the plasma becomes severe. There was a problem that it was consumed by etching.

Further, even when a corrosion-resistant light metal material such as stainless steel or aluminum is used as the corrosion-resistant member, the corrosion resistance is insufficient. Particularly, if the corrosion-resistant light metal material is corroded, it may adversely affect the wafer in the manufacture of semiconductor devices. However, there is a problem that the defective product causes a defective product.

Further, in the case of an alumina sintered body or an aluminum nitride sintered body as a corrosion-resistant member, or a ceramic sintered body coated with a ceramic film, a halogen-based corrosive gas is used as compared with quartz glass or a corrosion-resistant light metal material. Despite having high corrosion resistance, there is a problem that corrosion gradually progresses when it comes into contact with plasma at high temperature, and the halide evaporates or becomes fine powder from the surface of the ceramic sintered body and is consumed. A material having high corrosion resistance has been desired.

[0007]

[Means for Solving the Problems] Accordingly, the present applicant has
After examining materials that have excellent corrosion resistance even when exposed to plasma in an atmosphere containing a halogen-based corrosive gas, a ceramic sintered body containing a magnesium (Mg) compound reacts with the halogen-based corrosive gas. It has been found that even if a halide is produced, the melting point is high and stable, so that it is excellent in corrosion resistance.

It has also been found that when a ceramic sintered body has a large number of pores or has a large number of grain boundary phases, it is susceptible to corrosion and the corrosion resistance is greatly reduced.

That is, according to the present invention, a corrosion-resistant member exposed to plasma in an atmosphere in which a halogen-based corrosive gas such as a fluorine-based or chlorine-based gas is present is prepared by adding 15% by weight of MgO in terms of oxide.
As described above, Al ₂ O ₃ is contained in a range of 85% by weight or less, and M
gO, MgAl ₂ O ₄ and MgO, MgAl ₂ O ₄ , Mg
Consisting of any of the crystal phases of Al ₂ O ₄ and Al ₂ O ₃ ,
It is characterized by being formed of a ceramic sintered body having an average crystal grain diameter of the crystal phase of 3 μm or more and a porosity of 0.2% or less.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The corrosion-resistant member of the present invention is a member that is exposed to plasma under a halogen-based corrosive gas, and includes SF ₆ , CF ₄ , CH
Fluorine gas such as F ₃ , CIF ₃ , HF, Cl ₂ , BC
chlorine gas such as l ₃ , HCl, CCl ₄ or Br
_2, HBr, and the like bromine-based gas such as CBr _4. When high-frequency waves or microwaves are introduced in an atmosphere in which these halogen-based corrosive gases are used, these gases are turned into plasma.

In order to further enhance the etching effect, plasma may be generated by introducing an inert gas such as Ar together with a halogen-based corrosive gas.

According to the present invention, a corrosion-resistant member exposed to plasma under these halogen-based corrosive gases is made of MgO, MgA.
It is formed of a ceramic sintered body composed of any one of crystalline phases of l ₂ O ₄ and MgO, MgAl ₂ O ₄ , and MgAl ₂ O ₄ and Al ₂ O ₃ .

That is, MgO and MgAl ₂ O ₄ constituting the crystal phase of the ceramic sintered body mainly produce MgF ₂ when reacting with a fluorine-based gas, and mainly produce MgCl ₂ when reacting with a chlorine-based gas. However, the melting points of these halides (MgF ₂ : 1260 ° C, MgCl ₂ : 714
° C.) is the melting point of the halide formed by the reaction of a conventional quartz glass or alumina sintered body or an aluminum nitride sintered body _{(SiF 4: -90 ℃, SiCl} 4: -7
0 ° C., AlF ₃ : 1040 ° C., AlCl ₃ 178 ° C.)
Since it is higher, it has both stable heat resistance and corrosion resistance even when exposed to plasma at a high temperature, and can enhance corrosion resistance to plasma under a halogen-based corrosive gas.

Here, MgAl ₂ O ₄ means MgO and A
The theoretical constant ratio of l ₂ O ₃ is 28.6: 71.4 by weight.
(1: 1 molar ratio). When the composition ratio of MgO and Al ₂ O ₃ is changed variously, substantially only MgAl ₂ O ₄ crystals are present at the theoretical stoichiometric ratio.
gAl ₂ O _{4 has} a two-phase crystal structure. On the other hand, when Al ₂ O ₃ is more than the theoretical stoichiometric ratio, Al ₂ O ₃ and MgAl ₂ O ₄
Has a two-phase crystal structure.

[0015] The applicant of the present invention has been described as MgO, MgAl
₂ O ₄ and MgO, MgAl ₂ O ₄ , MgAl ₂ O ₄ and A
The content of the ceramic sintered body made of any crystalline phase of l ₂ O _3, MgO and 15 wt% or more in terms of oxide, A
It has been found that by setting l ₂ O ₃ to less than 85% by weight, a corrosion-resistant member having excellent corrosion resistance to plasma under a halogen-based corrosive gas can be obtained.

That is, the content of MgO in terms of oxide is 1
When the content is less than 5% by weight (the content of Al ₂ O _{3 in} terms of oxide is more than 85% by weight), the amount of the Al ₂ O ₃ crystal phase in the ceramic sintered body becomes too large. This is because it becomes susceptible to corrosion by halogen plasma.

Further, in order to improve the corrosion resistance of the ceramic sintered body constituting the corrosion resistant member, the porosity is set to 0.2% or less, and MgO, which constitutes the ceramic sintered body,
The average crystal grain size of MgAl ₂ O ₄ and Al ₂ O ₃ is 3 μm
Above, preferably, the porosity is 0.1% or less, MgO, Mg
The average crystal particle diameter of Al ₂ O ₄ and Al ₂ O ₃ is preferably set to 15 μm or more.

This is because, when pores exist in the ceramic sintered body, the edges of the pores are easily eroded by plasma,
If the porosity exceeds 0.2%, the progress of corrosion is accelerated. If the average crystal particle diameter of MgO, MgAl ₂ O ₄ , and Al ₂ O ₃ is less than 3 μm, corrosion is likely to occur due to plasma. As the grain boundary phase increases, the porosity is reduced to 0.
This is because it cannot be less than 2%.

In the present invention, the average crystal grain size of the crystal phase means that in the case of a ceramic sintered body mainly composed of MgO or MgAl ₂ O ₄ , MgO crystal or MgAl
And that the average crystal grain size of ₂ O ₄ crystal, MgAl ₂
In the case of a ceramic sintered body mainly composed of O ₄ and MgO or MgAl ₂ O ₄ and Al ₂ O ₃ , MgAl ₂ O ₄ crystal and MgO crystal or MgAl ₂ O ₄ crystal and Al ₂ O ₃
It is the average crystal particle diameter when the crystals are measured together. And as a method of measuring the average crystal particle diameter,
Any surface or cross section of the corrosion resistant member can be obtained by enlarging it with a metallurgical microscope or an electron microscope (SEM) and analyzing it with an image analysis device. Prepare an SEM photograph,
After arbitrarily drawing ten lines on this SEM photograph, the value obtained by dividing the total length of the line by the number of crystals located on the line may be used as the average crystal particle diameter.

The porosity of the ceramic sintered body can be determined by the Archimedes method, the crystal phase can be determined by X-ray diffraction, and the content can be determined by ICP or X-ray fluorescence.

Further, the ceramic sintered body constituting the corrosion resistant member includes SiO ₂ , CaO, Na ₂ O, Fe ₂ O ₃
And the like may be contained as impurity components. However, since the melting point of the halide generated by the reaction of these impurity components with the halogen-based corrosive gas is not so high, the amount of impurities such as Al ₂ O _{If the} content is more than 1 part by weight with respect to 100 parts by weight of the total of ₃ and MgO, corrosion will be greatly caused.

Therefore, the amount of these impurities is desirably 1 part by weight or less with respect to the total of 100 parts by weight of Al ₂ O ₃ and MgO constituting the main components. , High purity Al ₂ O ₃ and Mg as starting materials
O may be used, and contamination of impurities during the manufacturing process may be prevented.

Hereinafter, a method for manufacturing a corrosion-resistant member according to the present invention will be described.

First, when less than 85% by weight of Al ₂ O ₃ having a purity of 99% or more and an average particle diameter of 0.1 to 5 μm, the purity of the powder is 99% or more and an average particle diameter of 0.1 to 5 μm. MgO
Is added at a ratio of 15% by weight or more, and a binder and a solvent are added and mixed to produce a slurry. The slurry is subjected to a predetermined ceramic molding method such as an extrusion molding method, an injection molding method, or a doctor blade method. Alternatively, the slurry is granulated by a spray dryer to produce granules, and then filled into a mold and formed into a predetermined shape by a die press molding method or a rubber press molding method.

Thereafter, these compacts are heated at a temperature of 1500 to 1700 ° C. in an air atmosphere or a vacuum atmosphere.
By firing for about 10 hours, MgO, MgAl
₂ O ₄ and MgO, MgAl ₂ O ₄ , MgAl ₂ O ₄ and A
A corrosion-resistant member made of any one of the crystal phases of l ₂ O ₃ can be obtained.

(Example 1) As a corrosion-resistant member of the present invention,
A ceramic sintered body composed of a crystal phase of MgAl ₂ O ₄ and MgO, and quartz glass having a purity of 9 as a conventional corrosion-resistant member.
A 9.5% alumina sintered body and a 99.9% pure alumina sintered body were prepared, respectively, and an experiment was conducted on corrosion resistance when exposed to plasma under a fluorine-based or chlorine-based corrosive gas.

In this experiment, the present invention and the conventional corrosion-resistant member were formed into a sample having a diameter of 30 mm × thickness of 3 mm, and then subjected to a lapping process to obtain a mirror-finished surface, and this sample was set in an RIE plasma apparatus. Plasma was generated by introducing high frequency waves in an SF ₆ gas atmosphere and a Cl ₂ gas atmosphere, and after exposing for 3 hours in these plasmas, the etching rate per minute was calculated from the weight loss before and after the treatment. Calculated.

The corrosion-resistant member of the present invention includes Al ₂ O
₃ After adding a solvent and a binder to 70% by weight and 30% by weight of MgO, mixing them for about 10 hours, granulating them with a spray dryer to prepare granules, filling the granules in a mold, and pressing the granules by a mechanical press method. A cylindrical body is formed by applying a pressure of about 0.0 ton / cm ^{2, and} thereafter,
What was manufactured by firing at a temperature of 1700 ° C. for 2 hours in an air atmosphere was used.

The properties of each sample and the results are as shown in Table 1.

[0030]

[Table 1]

As a result, the corrosion-resistant member of the present invention was SF ₆
The etching rate could be set to 20 ° / min or less for both corrosive gases such as gas and Cl ₂ gas, and had excellent corrosion resistance as compared with conventional corrosion-resistant members.

Example 2 Next, as a corrosion-resistant member, A
MgO, MgAl ₂ O ₄ and MgO, MgO, MgAl ₂ O ₄ , which were manufactured with different contents of l ₂ O ₃ and MgO,
A ceramic sintered body composed of any one of MgAl ₂ O ₄ and Al ₂ O ₃ crystal phases was manufactured, and an experiment was performed on corrosion resistance when exposed to plasma under a fluorine-based or chlorine-based corrosive gas.

In this experiment, Al ₂ O ₃ and MgO were added in the proportions shown in Table 1, respectively, a solvent and a binder were added and mixed for about 10 hours, and then granulated by a spray dryer to produce granules. The granules are filled in a mold and pressed by a mechanical press method at a pressure of about 1.0 ton / cm ² to form a columnar body, and then fired at 1700 ° C. for 2 hours in an air atmosphere. What was produced by doing it was used.

Then, after cutting these ceramic sintered bodies to a diameter of 30 mm × thickness of 3 mm, lapping was performed to obtain mirror-finished surfaces, and these samples were set in an RIE plasma apparatus. Plasma is generated by introducing high frequency waves in SF ₆ gas atmosphere and Cl ₂ gas atmosphere, and after exposing for 3 hours in these plasmas, the etching rate per minute is calculated from the weight loss before and after the treatment. did.

Table 2 shows the characteristics of each sample, and Table 3 shows the results.

[0036]

[Table 2]

[0037]

[Table 3]

As a result, MgO was less than 15% by weight (Al
₂ O ₃ is more than 85% by weight), since the amount of Al ₂ O ₃ crystals in the ceramic sintered body is large, the etching rate in the SF ₆ gas atmosphere is 70 ° / min, and the etching rate in the Cl ₂ gas atmosphere is 70% / min. Is about 120Å / min,
The corrosion resistance was about the same as that of the alumina sintered body having a purity of 99.9% used in Example 1.

On the other hand, MgO of 15% by weight or more (A
(85% by weight or less of l ₂ O ₃ ), the corrosion under SF ₆ gas atmosphere can be reduced to 30 ° / min or less, and the corrosion under Cl ₂ gas atmosphere can be reduced to 50 ° / min or less. Had. In particular, when MgO is 30% by weight or more (Al ₂ O ₃ is 70% by weight or less), corrosion in an atmosphere of SF ₆ gas and Cl ₂ gas is 20% or less.
Å / min or less, and further, in a ceramic sintered body made of only MgO, corrosion in an atmosphere of SF ₆ gas and Cl ₂ gas could be reduced to 5 Å / min.

(Example 3) Further, the sample No. 3
An experiment was performed on the corrosion resistance when the porosity and the average particle size were varied by controlling the firing temperature using the ceramic sintered body of Example 1 under the same conditions as in Example 1.

Table 4 shows the porosity and average particle size of the ceramic sintered body, and Table 5 shows the results.

[0042]

[Table 4]

[0043]

[Table 5]

[0044] As a result, the samples A, B are both porosity greater than 0.2%, also, MgAl ₂ O ₄ and Mg
Since the average crystal particle diameter of O was less than 3 μm, the edges of the pores and the grain boundary phase portion were eroded and corroded significantly.

On the other hand, Samples C to F have a porosity of 0.
Since the average crystal particle diameter of MgAl ₂ O ₄ crystal and MgO crystal is 3 μm or more, corrosion in SF ₆ gas atmosphere is 30 ° / min or less, and corrosion in Cl ₂ gas atmosphere is 50 ° / min. It had the following excellent corrosion resistance.

The relationship between the average crystal grain size of the crystal phase and the porosity in this experiment is shown in Table 2 for sample no. 1,2,4 ~
A similar tendency was observed in the ceramic sintered body of No. 8.

[0047]

As described above, according to the present invention, the corrosion-resistant member is made of MgO of not less than 15% by weight and Al ₂
O ₃ was contained in an amount of 85 wt% or less, MgO, MGA
It is composed of any one crystal phase of l ₂ O ₄ and MgO, MgAl ₂ O ₄ , MgAl ₂ O ₄ and Al ₂ O ₃ , and the average crystal particle diameter of the crystal phase is 3 μm or more and the porosity is 0.2% Since it is formed of the following ceramic sintered body, it has excellent corrosion resistance even when exposed to plasma under an atmosphere in which a halogen-based corrosive gas such as a fluorine-based or chlorine-based gas is present. It can be suitably used as a jig such as a wafer holder and a clamp ring to be used, an inner wall material, or a member such as a protective tube for plasma generation used in a CFC decomposition apparatus or an excimer laser.

Claims (1)

[Claims] 1. A member exposed to plasma in an atmosphere containing a halogen-based corrosive gas contains 15% by weight or more of MgO and 85% by weight or less of Al ₂ O ₃ in terms of oxide. , MgAl ₂ O ₄ and MgO, MgAl
_A ceramic sintered body comprising a crystal phase of any one of ₂ O ₄ , MgAl ₂ O ₄ and Al ₂ O ₃ , wherein the crystal phase has an average crystal particle diameter of 3 μm or more and a porosity of 0.2% or less. Corrosion resistant member.