JP2002179457A - Corrosion-resisting member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems that a conventionally used sintered body of glass, quartz, stainless, steel alumina, aluminum nitride does not exhibit sufficient corrosion resistance to a fluorine based plasma, and in the sintered body, corrosion gradually advances and the degranulation of crystal particles is caused from the surface of the sintered body and particles are produced. SOLUTION: A site exposed to a fluorine based corrosive gas such as CF4 and SF6 or its plasma is constituted of a sintered body of the element of group IIIa ion the periodic table such as Y, La, Ce, Nd and Dy and the multiple oxide containing Si (not containing Al), for example, disilicate and monosilicate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inner wall material or a jig in a plasma processing apparatus, a semiconductor manufacturing or a plasma processing apparatus for a liquid crystal, which has a high corrosion resistance especially to a fluorine-based corrosive gas and a fluorine-based plasma. The present invention relates to a corrosion-resistant member used as a member.

[0002]

2. Description of the Related Art The use of plasma, such as a dry process for semiconductor manufacturing and plasma coating, has been rapidly advancing in recent years. As a plasma process in a semiconductor, a halogen-based corrosive gas such as a fluorine-based gas is used for vapor phase growth, etching and cleaning due to its high reactivity.

[0003] The members that come into contact with these corrosive gases are required to have high corrosion resistance. Conventionally, the members that come into contact with these plasmas other than the object to be processed are generally made of Si such as glass or quartz.
Materials containing O ₂ as a main component and corrosion-resistant metals such as stainless steel and Monel are often used.

[0004] In the manufacture of semiconductors, as a susceptor material for supporting and fixing a wafer, a sintered body of alumina, sapphire, or a sintered body of AlN, or a surface-coated body thereof by a CVD method or the like is used as having excellent corrosion resistance. I have. Further, a heater coated with graphite or boron nitride is also used.

[0005]

However, the glass and quartz used conventionally have insufficient corrosion resistance in plasma and are intensely depleted. In particular, when they come into contact with fluorine plasma, the contact surface is etched and the surface properties change. In the case of a member that requires light transmissivity, there have been problems such as that the surface gradually becomes cloudy and the light transmissivity decreases.

[0006] Further, even members made of metal such as stainless steel have insufficient corrosion resistance, so that corrosion causes a defective product, particularly in semiconductor manufacturing.

[0007] Alumina and AlN sintered bodies are more excellent in corrosion resistance to fluorine-based gas than the above materials, but when they come into contact with plasma at high temperature, the corrosion gradually progresses, and the surface of the sintered body crystallizes. There is a problem that particles are shed and cause particles to be generated.

[0008]

Means for Solving the Problems The present inventors have repeatedly studied methods for improving the corrosion resistance to a fluorine-based corrosive gas and plasma. The generation of fluoride having a melting point, in particular, a composite oxide of a Group 3a element of the periodic table and Si can be obtained at a low cost, and the fluoride forms a stable fluoride layer on the surface to cause corrosion of members. It has been found that the corrosion resistance is suppressed, and the corrosion resistance superior to conventional alumina, glass, AlN, Si ₃ N _{4 and the} like can be realized.

That is, the corrosion-resistant member of the present invention has been completed based on the above findings, and at least a portion of the corrosion-resistant member exposed to a fluorine-based corrosive gas or its plasma is in direct contact with the corrosive gas or plasma. , A composite oxide containing a Group 3a element of the periodic table and Si (however, Al
), It is possible to provide a relatively inexpensive member having long-time resistance in a high-temperature, high-density fluorine-based corrosive atmosphere.

According to the present invention, by using a composite oxide material (but not including Al) containing a Group 3a element of the periodic table and Si as a member exposed to a fluorine-based gas and plasma, A stable fluoride layer is generated on the surface by the reaction with fluorine, and the resistance to a severe fluorine-based corrosive atmosphere is improved over a wide temperature range.

Further, by suppressing the precipitation of elemental compounds such as Si, Ge, Mo, W, etc., which easily react with fluorine and volatilize, at the grain boundaries and prevent their ubiquity, local corrosion resistance can be prevented. It is possible to prevent the reduction of the particle size and the generation of particles that fall due to the reduction, and to further improve the corrosion resistance. These elements evaporate during the early stages of corrosion,
The fluoride containing the Group 3a element of the periodic table remains on the material surface, and a fluoride layer rich in the Group 3a element of the periodic table is gradually formed. As a result, the progress of corrosion can be suppressed.

Moreover, the composite oxide containing a Group 3a element of the periodic table and Si is more easily formed by a thin film technique such as a PVD method and a CVD method than the group 3a element oxide of the periodic table. Since it can be manufactured as a dense sintered body without stopping, it can be adapted to all shaped products.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The corrosion-resistant member of the present invention is a member that is exposed to a fluorine-based corrosive gas or a fluorine-based plasma. Examples of the fluorine-based gas include SF ₆ , CF ₄ , CHF ₃ , and the like.
ClF ₃ , HF and the like can be mentioned. When a microwave or a high frequency is introduced into an atmosphere in which these gases are introduced, these gases are turned into plasma.

According to the present invention, the portion exposed to such a fluorine-based gas or its plasma is made of a composite oxide containing at least a Group 3a element of the periodic table and Si. However, it does not contain Al. Here, Sc, as an element belonging to Group 3a of the periodic table constituting the composite oxide, is Sc,
Y, La, Ce, Nd, Sm, Eu, Tb, Dy, H
Although any of o, Er, Tm, Yb, Lu and the like can be used, Y, La, Ce, Nd, and Dy are particularly desirable in terms of cost.

[0015] The corrosion resistance of this composite oxide is 3a of the periodic table.
Greatly influenced by the amount of group elements, group 3a elements of the periodic table
30 atomic% or more, especially 4%, of all metal elements in the composite oxide
Desirably, it is present at 0 atomic% or more. This is because if the amount of the element of Group 3a of the periodic table is less than 30 atomic%, the initial corrosion in the halogenated gas or its plasma is severe and a protective layer is gradually formed on the surface, but it takes a long time. Not practical.

The composite oxide may be a single crystal in addition to the above-mentioned glass and ceramic sintered body containing at least two types of metal elements. When the corrosion resistance of the grain boundary phase precipitated in the steel is remarkably inferior to that of the main crystal grains, the grain boundary phase is selectively corroded, causing degranulation and generation of particles. Therefore, the content of Si, Ge, Mo, and W, which are easily corroded by fluorine, in the grain boundaries is preferably suppressed to 1% by weight or less of the total amount. This does not apply when these elements which are easily corroded by fluorine are dissolved in the main crystal grains and do not exist at the grain boundaries.

The composite oxide is desirably mainly composed of a crystalline material. Particularly, a garnet crystal, a monoclinic crystal, a perovskite crystal, and a monosilicate (Y ₂ O _3.
A material mainly composed of a silicate compound such as SiO ₂ ) or disilicate (Y ₂ O ₃ .2SiO ₂ ) is desirable in that it has excellent corrosion resistance. Among these, garnet-type crystals and disilicate-type crystals are most desirable in terms of sinterability and low production cost. Alternatively, examples of oxides other than those described above include those in which Si constitutes a main crystal phase, such as a composite oxide such as RE (Nd), Si, and Al.

The above-mentioned sintered body of the composite oxide is fired, for example, in a oxidizing atmosphere or a vacuum atmosphere at a temperature of 1100 to 1900 ° C. from a mixture of a Group 3a element oxide of the periodic table and SiO ₂ powder. It can be manufactured by the following.
As a firing method, a hot press method or the like is employed in addition to normal pressure firing.

The corrosion-resistant member of the present invention is not limited to the sintered body, but may be a thin film formed on a predetermined substrate surface by a known thin film forming method such as a PVD method or a CVD method. . Further, a thin film obtained by applying and baking a liquid phase by a well-known sol-gel method may be used. Among these, a sintered body obtained by molding and firing a powder is most desirable because of its excellent applicability to all members. The composite oxide is formed at a site exposed to a halogen-based corrosive gas or its plasma, and such a metal oxide must have at least a thickness of 10 μm or more to have excellent corrosion resistance. It is desirable in giving.
That is, if the thickness is less than 10 μm, excellent corrosion resistance cannot be expected.

[0020]

EXAMPLES Various oxide powders described in Table 1 were used using various oxide powders.
Was prepared. In Table 1, sample no. Tables 1 to 5 are
Rare earth oxides and SiO_TwoAt 2000 ° C
After being melted, it is rapidly cooled and vitrified. Sample N
o. 6, 7 is Y_TwoO_ThreeAnd SiO _TwoWere mixed in a predetermined ratio
The compact was fired at 1300 to 1600 ° C.

The various materials shown in Table 1 were used in RIE plasma.
Installed in the etching equipment, CF _FourAnd O_TwoMixed gas
(CF_Four: O_Two= 9: 1), Ar and SF₆Mixed gas (A
r: SF₆= 2: 3), and
Microwaves were introduced to generate plasma. This plastic
Hold for up to 3 hours in Zuma to reduce material weight before and after processing
Measure a small amount and etch from that value per minute
The thickness (etching rate) was calculated. Also, after the test
The surface condition of the sample was observed, and the results are shown in Table 1.

As a comparative example, a conventional BN sintered body,
Quartz glass, Si_ThreeN_FourSintered body, Al _TwoO_ThreeSintered body, AlN
The same test was performed on the sintered body.

[0023]

[Table 1]

As shown in Table 1, the conventional various materials (samples Nos. 6 to 13) of the comparative examples all had an etching rate of 70 ° / min or more, had a rough surface, and had an Si ₃ N _{4 In the} sintered body, generation of particles on the surface was confirmed. Many cavities due to etching were observed in the sintered bodies of Al ₂ O ₃ and AlN.

For these comparative examples, sample Nos. 1-5
All of the samples of the present invention showed high corrosion resistance to fluorine-based plasma. In particular, when the sample was made of glass, the formation of dents on the surface was confirmed, but in the case of the sintered body, the surface condition was excellent. In addition, it was confirmed that a fluoride layer rich in an element of Group 3a of the periodic table was formed on the surface of each of the samples of the present invention after the test.

[0026]

As described in detail above, according to the present invention, the member exposed to the fluorine-based corrosive gas and its plasma is made of a complex oxide of Group 3a element of the periodic table and Si. In addition, a stable fluoride layer is formed on at least the material surface, and high corrosion resistance is achieved in a severe fluorine-based corrosive atmosphere. Moreover, since a sintered body can be easily manufactured,
It can be applied to all shapes.

Claims (1)

[Claims] 1. A corrosion-resistant member wherein a portion exposed to a fluorine-based corrosive gas or its plasma is made of a complex oxide (but not containing Al) containing a Group 3a element of the periodic table and Si. .