JPH09180627A - Discharging container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the corrosion resistance of a discharging container and extend the life of the container by applying a single substance of group 2a element of the periodic table or its compound on the contact face with plasma in the discharging container generating plasma in it. SOLUTION: A film layer 4 made of a single substance of group 2a element of the periodic table or its compound is formed on the surface at least kept in contact with plasma on the inner face of the container wall 2 of a discharging container 1 generating plasma in it. The thickness of the film 4 is preferably set to about 0.001-1mm. At least one kind selected from a group of Ba, Mg, Ca, Sr, Ra is used for the 2a group element in the periodic table. A nitride, a carbide, a carbonitride, an oxide, an oxynitride, an oxycarbonitride, a halide, or a boride is used for the compound.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge vessel such as a discharge tube for internally generating plasma, a reaction tube of a plasma processing apparatus, a display tube, a Braun tube, and the like, and discharge having excellent plasma resistance and excellent durability. For containers.

[0002]

2. Description of the Related Art A discharge vessel for internally generating plasma is a dry process such as coating or etching,
It is used as a coating for plasma jet or high temperature plasma, powder generation, or as a discharge tube for a light source such as a halogen lamp or a discharge tube for a display.

Currently, in these discharge vessels, there are ions, high-speed particles, or dissociated electrons in the plasma inside the vessels, and in some cases, fluorine (F), chlorine (Cl), etc. are present. . As a material for forming the discharge container, a material containing SiO ₂ as a main component such as glass or quartz, a metal material such as stainless steel, or the like is generally used. In addition, silicon compounds such as Si ₃ N ₄ and SiC are also used as wear-resistant parts because they have high hardness and corrosion resistance, but they are also used as discharge containers because they have excellent electrical insulation and corrosion resistance. ing.

[0004]

However, glass and quartz are not sufficiently corrosion-resistant in plasma due to the impact of ions, high-speed particles or electrons in the plasma and chemical reaction by active species in the gas phase. In particular, when fluorine or chlorine is present in the plasma, the container is easily etched and consumed, or the initially transparent container gradually becomes whiter and its translucency is reduced, resulting in a short service life. . Further, when a metal such as stainless steel is used, metal atoms are mixed as impurities into the plasma by etching, which adversely affects the process.

Although the above silicon compounds such as Si ₃ N ₄ are superior in corrosion resistance to glass and quartz, they have sufficient plasma resistance especially in plasma containing fluorine (F) or chlorine (Cl). However, there is a problem that the surface is etched by the plasma and the consumption is severe.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies on materials having high corrosion resistance even in plasma containing halogen such as fluorine (F) and chlorine (Cl), and as a result, the periodic It has been found that the use of a material containing a simple substance or a compound of the Group 2a elements in the table as the main component for the discharge vessel can improve the characteristics and prolong the life. That is, the discharge vessel of the present invention is characterized in that at least a surface of the inner surface of the vessel wall which is in contact with plasma is made of a ceramic material containing a simple substance of a Group 2a element of the periodic table or a compound thereof as a main component. Is. Further, the container wall is made of metal, glass or ceramics as a base,
The inner surface thereof, which is in contact with plasma, is coated with a ceramic film containing a Group 2a element of the periodic table alone or a compound thereof in a thickness of 0.001 to 1 mm.

[0007]

According to the discharge vessel of the present invention, the contact surface with the plasma is formed of a simple substance or a compound of the Group 2a elements of the periodic table, so that the plasma, especially the plasma containing F or Cl The corrosion resistance can be remarkably improved, the life can be extended, and the inclusion of impurities such as metals in the process can be significantly reduced. Especially strong against chemical reaction with halogen, such as discharge tubes, display tubes,
Alternatively, when halogen is used in a semiconductor manufacturing process device or the like, a significant improvement in life is achieved as compared with conventional materials.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described by taking a typical discharge tube as an example of a discharge vessel. FIG. 1 is a schematic view of a discharge tube. In FIG. 1, 1 is a discharge tube, 2 is a discharge tube wall, and 3 is an electrode.

According to the present invention, at least the surface of the inner surface of the discharge tube wall 2 of the discharge tube 1 in contact with the plasma is defined by the second periodic table.
It is made of a ceramic material containing a simple substance of the group a element or a compound thereof. Further, even if it is used for the electrode part or its surroundings, there is no problem as long as it is a part in contact with plasma.

The elements of Group 2a of the periodic table used are B
Examples thereof include at least one selected from the group consisting of a, Mg, Ca, Sr, and Ra. Examples of these compounds include nitrides, carbides, carbonitrides, oxides, oxynitrides, oxynitride carbides, and halides. , Or at least one boride as a main component. For example, in the case of magnesium, magnesium nitride, magnesium carbide, magnesium oxide, magnesium fluoride, magnesium boride and the like can be mentioned. In particular, when two or more kinds are used, compounds of the same kind such as oxides or nitrides are preferable.

These elements of Group 2a of the periodic table or their compounds may constitute the discharge wall 2 by themselves, but there is a problem in strength and the like.
As described above, the coating layer 4 made of the Group 2a element of the periodic table or its compound may be formed on the inner surface of the discharge tube wall 2 which is in contact with the plasma. In that case, since various materials can be selected as the container base, the strength of the discharge tube itself can be increased by using a material having high strength. The base material used may be any of metal, glass and ceramics, and can be selected according to the shape of the product, cost, required characteristics and the like. For example, when plasma is used in a low temperature region, metal such as stainless steel can be used. Further, when low cost and transparency are required, such as a lamp, glass may be used. Further, when the wall is exposed to a high temperature and translucency is not required so much, silicon nitride or silicon carbide may be used.

As a method for forming the coating layer 4, a known method such as plating, a sol-gel method, a gas phase reaction method may be used. However, since each method has a characteristic that adhesion is low in plating and a non-oxide film cannot be formed by the sol-gel method, the coating method may be determined in accordance with the cost and required characteristics. Further, the vapor phase reaction method includes PVD methods such as vacuum vapor deposition, sputtering, ion plating, cluster beam (CBD) method, and ion vapor deposition (IVD) method, thermal CVD method, plasma CVD method, photo CVD method.
Methods, laser CVD methods, MOCVD methods, and other CVD methods, and any of them may be used.

In the present invention, when the coating layer 4 is formed by a well-known thin film forming method, the coating layer 4 has a thickness of 0.0
It is desirable that the film is formed with a film thickness of 01 mm to 1 mm, particularly 0.01 to 0.1 mm. This is 0.001mm
If the thickness is thinner, the life will be shortened, and if it exceeds 1 mm, the manufacturing cost for film formation increases, and the surface becomes rough, which is not practical except for special applications. The coating layer may be a single layer, but it may be a multi-layered film having two or more layers in consideration of adhesion to the substrate and thermal conductivity.

[0014]

【Example】

Example 1 Melt Calcium Fluoride (CaF ₂ ) and Quartz (Si
O ₂ ) was used in a container of a fluorine plasma generator using fluorine sulfur (SF ₆ ) as a discharge gas. The weight loss after use was measured after exposing each container to a discharge gas for 100 hours. The results are shown in Sample Nos. 1 and 2 in Table 1.

Example 2 A zirconia tube having a diameter of 40 mm and a length of 500 mm was used as a substrate, and MgCl ₂ and CO ₂ were used as reaction gases on the inner surface of the substrate to form a coating layer made of magnesium oxide by the CVD method. The thickness of the coating layer is 0.8 to 970.
Coating layers with various thicknesses were formed by changing the thickness in the range of μm. Using this tube as a plasma discharge tube, bromine (Br
₂ ) Example 1 for confirming the corrosion resistance to plasma
The weight loss was measured in the same manner as in. The results are shown in Sample Nos. 3 to 7 in Table 1.

Example 3 A silicon carbide sintered body obtained by sintering carbon and boron as a sintering aid was used as a substrate, and its surface was coated with barium (Ba) by a sputtering method. Then, this is added to a plasma containing fluorine carbide (CF ₄ + O ₂ ) as a discharge gas.
As a comparison, the weight loss after holding for 00 hours was also measured for those without a coating layer. The results are shown in Table 1 for sample No.
8 and 9.

Chlorine plasma discharge by high frequency was performed using the coated silicon carbide sintered body as one electrode and the silicon carbide sintered body as the counter electrode. As a result, the etching rate for chlorine plasma was 1/100 in the sample with the coating layer formed thereon, compared with the sample without the coating layer.

Example 4 A lamp material made of translucent alumina was used as a substrate, and the surface thereof was coated with a Mg compound by a sol-gel method or a sputtering method. This was kept in bromine iodide (IBr) plasma and the weight loss after 100 hours was measured. The results are shown in Sample Nos. 10 to 13 of Table 1. By forming the magnesium oxide coating layer, the corrosion resistance was significantly improved.

Example 5 Various samples shown in Table 1 were used as a substrate, and a sample whose surface was coated with a compound of the Group 2a element of the periodic table or a sample made of a bulk body made of the materials shown in Table 1 was chlorinated. Weight loss in fluorine (ClF ₃ ) plasma was measured. The results are shown in Sample Nos. 14 to 27 of Table 1.

[0020]

[Table 1]

As is clear from the results in Table 1, the quartz alone, the silicon carbide based sintered body alone, the translucent alumina, and the silicon nitride based sintered body had large weight changes, but the cycle It was understood that by coating with a Group 2a element alone or a compound thereof, the weight change amount was 0.05% or less, and the durability against plasma was improved.

[0022]

As described in detail above, according to the present invention, by forming at least the surface of the inner surface of the container in which plasma is in contact with plasma by a simple substance or a compound of Group 2a elements of the periodic table, The consumption of the container wall can be significantly reduced and the life can be extended. In particular, a highly functional container can be formed by forming a coating layer on the surface of the container material in contact with plasma.

[Brief description of the drawings]

FIG. 1 is a schematic view of a discharge tube according to the present invention.

[Explanation of symbols]

 1 discharge tube 2 discharge tube wall 3 electrode 4 coating layer

Claims (2)

[Claims] 1. A discharge vessel for generating plasma inside, wherein at least a surface of the inner surface of the vessel wall which is in contact with plasma is made of a simple substance of a Group 2a element of the periodic table or a compound thereof. Discharge container. 2. The container wall is made of metal, glass or ceramics as a substrate, and a coating layer made of a Group 2a element of the periodic table or its compound is formed on the inner surface of the container which is in contact with plasma. The discharge container according to claim 1.