JP2001151559A - Corrosion-resistant member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a corrosion-resistant member in which evaporation or generation of particles is hardly caused by a gaseous halogenated compound or its plasma and which has a long service life and long cleaning intervals. SOLUTION: This member which contains, as metal components, Al and at least one of rare earth elements and is comprised of a sintered body whose main crystal phase consists essentially of a compound oxide of Al and the rare earth element(s), has: a <=500 ppm total content of metal elements other than Al and the rare earth element(s); a >=98% relative density; a <=10 μm maximum grain size of crystal grains of the main crystal phase; a dielectric constant of <=13 in the frequency range of 0.4 MHz to 10 GHz; and a dielectric loss of <=5×10-4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corrosion-resistant member having high corrosion resistance to fluorine-based and chlorine-based corrosive gas atmospheres, particularly to fluorine-based and chlorine-based plasma, and more particularly to a plasma process in a semiconductor manufacturing apparatus. The present invention relates to a corrosion-resistant member suitable for a member used as a jig such as a member for a plasma processing apparatus such as a focus ring, a clamp ring, a bell jar and a dome, and a support for supporting an object to be processed.

[0002]

2. Description of the Related Art In recent years, the use of plasma, such as a dry process and plasma coating, used for manufacturing highly integrated circuit devices such as semiconductor devices and liquid crystals has been rapidly advancing. As a plasma process in semiconductor manufacturing, 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.

The members exposed to these corrosive gases are required to have high corrosion resistance. Conventionally, members that come into contact with the plasma other than the object to be processed are required to have high corrosion resistance and not contain impurities that cause contamination of non-processed objects or particles as much as possible. Conventionally, as members other than the object to be processed, which come into contact with the plasma, generally, a material mainly composed of SiO ₂ such as glass or quartz, a metal such as stainless steel or Monel, and an alumina as a ceramic material have begun to be used. In particular, alumina is used in a semiconductor manufacturing process as a corrosion-resistant member because a high-purity sintered body can be manufactured relatively inexpensively and has excellent corrosion resistance.

[0004] For example, in Japanese Patent Application Laid-Open No. Hei 5-217946, alumina is 99.9% or more and SiO ₂ is 100 p.
pm, a polycrystalline alumina-based sintered body containing 50 ppm or less of an alkali metal oxide, having a specific gravity of 3.96 or more, an average crystal grain size of 10 μm or more, and a dielectric loss tan δ of 8 × 10 4 at a microwave of 1 to 10 GHz. ^-4 or less is disclosed. The alumina-based bell jar has improved corrosion resistance to fluorine plasma as compared with conventional quartz glass, and has less absorption of microwaves and can prevent cracks and cracks.

However, alumina disclosed in Japanese Patent Application Laid-Open No. 5-217946 has a fluorine-based gas as compared with a material containing SiO ₂ as a main component such as glass or quartz, or a metal such as stainless steel or Monel. Although they are excellent in corrosion resistance to plasmas of chlorine and chlorine-based gases, they are not sufficient, so that when they are exposed to plasmas of these gases, corrosion gradually progresses. Corrosion evaporates as fluoride, chloride, or the like, and precipitates at a portion having a relatively low plasma density or a portion having a low temperature, thereby depositing an Al compound.

[0006] As described above, deposits are deposited in the process chamber, and the thickness increases with time. And
When a certain thickness is reached, the internal stress exceeds the adhesive force and peels off from the wall surface or the jig surface. Further, when the film becomes thicker, the film breaks and scatters in the process chamber.

At present, the use of high-density plasma has been promoted in order to increase the degree of integration of elements. In particular, in the process of processing an insulating film, these members have been further purified and, at the same time, have been made non-particle-free without generation of particles. Therefore, the generation of such foreign matter is treated in the same way as the generation of particles, and as the integration of semiconductors increases and the process becomes even cleaner, the element characteristics deteriorate due to disconnection of metal wiring and pattern defects. There is a risk of causing problems such as a decrease in yield and yield.

Further, it is necessary to clean the inside of the chamber at regular intervals and replace the jig with respect to the attached matter. In order to do so, the normal semiconductor manufacturing process is stopped, so the throughput becomes worse,
This has been one of the causes of higher semiconductor costs. That is, when alumina is used as the inner wall and the jig of the chamber as compared with the conventional material, the time until cleaning is improved, but it is not yet satisfactory.

Therefore, the present inventor has disclosed in Japanese Patent Laid-Open No. 10-675.
As shown in Japanese Patent Publication No. 54, a composite oxide of Al and a rare earth element is used as a main crystal phase, and the periodic table 2a, 3a group, Cr,
A corrosion-resistant ceramic member made of a ceramic sintered body having a grain boundary phase made of a compound mainly containing at least one of Co and Ni has been proposed. This member was significantly superior in corrosion resistance as compared with alumina, and was able to strengthen the grain boundaries to suppress the generation of particles, prolong the life and extend the time until cleaning.

[0010]

However, when used in the above-mentioned corrosion-resistant ceramic member, particularly a chamber or a jig used inside or around the plasma, if the dielectric loss is large, the high frequency introduced to generate the plasma is generated. The chambers and jigs are heated by, the corrosion resistance which was good at room temperature may be deteriorated, and depending on the gas and plasma conditions to be handled, the evaporation amount increases and the life is shortened,
There is a problem that the time until cleaning becomes short and stable characteristics cannot be obtained.

Further, since the dielectric loss of the grain boundary phase is high, it is heated at a high frequency and the temperature rises, so that the corrosion of the grain boundary phase is accelerated, particles are generated, and disconnection of the metal wiring, pattern defects, etc. There has been a problem of causing inconveniences such as deterioration of device characteristics and yield.

Therefore, according to the present invention, evaporation and generation of particles with respect to the halogenated gas and its plasma are reduced,
An object of the present invention is to provide a corrosion-resistant member having a long life and a long cleaning interval.

[0013]

The corrosion-resistant member of the present invention comprises:
Al as a metal component and at least one of rare earth elements
A main crystal phase comprising a sintered body mainly composed of a composite oxide of Al and a rare earth element, a metal element other than Al and the rare earth element being 500 ppm or less, a relative density of 98% or more, and the main crystal Maximum phase particle size of 10μ
m or less, a dielectric constant of 13 or less and a dielectric loss of 5 × 10 ⁻⁴ in a frequency range of 0.4 MHz to 10 GHz.
It is characterized by the following.

By employing this configuration, the amount of evaporation of Al and rare earth elements is significantly reduced as compared with alumina, and the amount of deposits adhering to the chamber wall surface and the jig surface is significantly reduced. Although the thickness of the precipitate gradually grows, it takes 2 to 10 times as long as that of alumina, so that the interval until cleaning can be extended. In addition, since the corrosion resistance is excellent, the life is extended, and the parts are extended. The replacement cycle can be lengthened. Furthermore, since the amount of crystalline and amorphous alumina is small at the grain boundaries, there is no selective grain boundary etching, and the generation of particles is suppressed.

Since the composite oxide is mainly composed of a garnet-type crystal and further contains a perovskite-type crystal and / or a rare-earth oxide crystal, it is possible to prevent alumina having poor corrosion resistance from existing alone as a crystal or a grain boundary phase. ,
In addition to preventing deterioration of the surface due to plasma irradiation, the Al element that repeatedly vaporizes and precipitates easily in the plasma can be incorporated into the rare-earth composite oxide to prevent dissociation of the Al element into the plasma.

Here, the amount of the alumina crystal particles is 1% by volume or less in the total amount, and the atomic ratio represented by RE / Al of the rare earth element (RE) to the aluminum element (Al) is 0.1%.
It is preferably 6 to 0.7 in order to prevent deterioration of the material surface due to selective etching of alumina during plasma irradiation.

Alternatively, the composite oxide is mainly composed of perovskite-type crystals, and further has a melilite-type crystal and / or
Alternatively, by containing the rare earth oxide crystal, the Al element is taken into the rare earth composite oxide, and the dissociation of the Al element into the plasma can be easily prevented.

Here, the amount of the alumina crystal particles is 1% by volume or less in the total amount, and the atomic ratio represented by RE / Al of the rare earth element (RE) to the aluminum element (Al) is 0.1%.
It is preferable that it is 67 to 1.7 in order to suppress the precipitation of alumina alone.

Further, since the composite oxide is mainly composed of a melilite-type crystal and further contains a perovskite-type crystal and / or a rare-earth oxide crystal, the ratio of the rare-earth element is increased, and the Al element is contained in the rare-earth composite oxide. It becomes easier to take in, and it becomes easier to prevent dissociation of the Al element into the plasma.

Here, the amount of alumina crystal particles is 1% by volume or less in the total amount, and the atomic ratio represented by RE / Al of the rare earth element (RE) to the aluminum element (Al) is 1.
It is preferable that it is 6 or more in order to suppress the precipitation of the alumina alone.

Therefore, according to the present invention, it is possible to provide a corrosion-resistant member having a long life with little evaporation and generation of particles with respect to the halogen-based gas plasma.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The corrosion-resistant member of the present invention contains Al as a metal component and at least one of rare earth elements, and has a main crystal phase mainly composed of a composite oxide of Al and a rare earth element. Although it is composed of a body, the presence of an impurity element can be a starting point for plasma corrosion, cause particles and contamination, and adversely affect device characteristics.
00 ppm or less is required. In addition, the pores in the material cause an increase in dielectric loss and, at the same time, serve as a starting point of etching like impurities, thereby impairing the life of the material. Therefore, a relative density of 98% or more is required.

Also, the maximum grain size of the crystal grains of the main crystal phase is 1
The reason why the particle diameter is set to 0 μm or less is that generation of particles increases when the particle diameter is large, and the number of generated particles can be reduced by setting the particle diameter to 10 μm or less.

Further, in the plasma process, 0.4M
A frequency band of 10 Hz to 10 GHz is generally used.
In systems such as CR (Electron Cyclotron Resonance) and ICP (Inductively Coupled Plasma), the dielectric constant is set to 1 in order to prevent energy from being raised due to energy absorption and deterioration in corrosion resistance.
It is necessary that the dielectric loss be 3 or less and the dielectric loss be 5 × 10 ⁻⁴ or less.

Further, it is desirable that the alumina crystal particles which are poor in corrosion resistance and are selectively etched in the plasma to cause degranulation and deterioration of surface properties are suppressed to 1% by volume or less in the total amount.

Further, the composite oxide is mainly composed of one of a garnet-type crystal, a perovskite-type crystal, and a melilite-type crystal, and is characterized by containing these crystals and / or a rare-earth oxide crystal.

When the corrosion-resistant member is mainly composed of a garnet-type crystal and contains a perovskite-type crystal and / or a rare-earth oxide crystal, the atomic ratio represented by RE / Al of the rare-earth element (RE) to the aluminum element (Al). Is preferably 0.6 to 0.7. This prevents alumina, which is inferior in corrosion resistance, from precipitating alone as a crystal grain or a grain boundary phase and preventing it from being selectively etched in the plasma, and incorporating Al element into the rare-earth composite oxide into the plasma. Dissociation and reprecipitation of the Al element can be suppressed, and the life of the member can be prolonged.

When the corrosion-resistant member is mainly composed of a perovskite crystal and is composed of a melilite crystal and / or a rare-earth oxide crystal, an atom represented by RE / Al of the rare-earth element (RE) with respect to the aluminum element (Al). Preferably, the ratio is between 0.67 and 1.7. This prevents alumina, which is inferior in corrosion resistance, from precipitating alone as a crystal grain or a grain boundary phase and preventing it from being selectively etched in the plasma, and incorporating Al element into the rare-earth composite oxide into the plasma. Dissociation of Al
It is possible to suppress re-deposition and prolong the life of the member.

Further, when the corrosion resistant member is mainly composed of a melilite type crystal and is composed of a perovskite type crystal and / or a rare earth oxide crystal, an atom represented by RE / Al of the rare earth element (RE) with respect to the aluminum element (Al). Preferably, the ratio is at least 1.6. This prevents alumina, which is inferior in corrosion resistance, from precipitating alone as a crystal grain or a grain boundary phase and preventing it from being selectively etched in the plasma, and incorporating Al element into the rare-earth composite oxide into the plasma. Dissociation and reprecipitation of the Al element can be suppressed, and the life of the member can be prolonged.

The corrosion-resistant member of the present invention can be manufactured as follows.

First, yttrium (Y) and erbium (Er) having a purity of 99% or more and an average particle diameter of 0.1 μm to 5 μm are used for a starting material of alumina powder having a purity of 99% or more and an average particle diameter of 0.1 μm to 5 μm. ), Ytterbium (Y
b), a rare earth oxide powder such as lanthanum (La), cerium (Ce), and neodymium (Nd) are mixed at a predetermined ratio. You can use these as they are,
It is desirable to use a raw material that has been calcined at a temperature of 1200 ° C. to 1500 ° C. to synthesize a composite oxide of Al and a rare earth element and pulverized to a particle size of 5 μm or less.

After adding an organic binder to the mixed powder as required, a known molding means, for example, a press molding method such as a mold press, a cold isostatic press, etc.
It is formed by a slip casting method, a tape forming method such as a doctor blade method, a rolling method, an extrusion method, or the like. Thereafter, the molded body is degreased in air, vacuum, or nitrogen, if desired, and then oxidized (La, C
e is in a non-oxidizing atmosphere) By baking at 1400 ° C. to 1800 ° C., particularly 1600 ° C. to 1750 ° C. for 1 to 10 hours, a dense body of 98% or more can be produced. As the firing method, a normal pressure firing method, a hot press method, a gas pressure firing method, or the like can be used, but the normal pressure firing method is preferable because of easy realization. Further, hot isostatic pressing may be performed to improve the density.

[0033]

EXAMPLE The purity of 99.8% was obtained using yttrium and erbium aluminum garnet raw material, YAM raw material and NdAlO ₃ having a purity of 99.9% and an average particle diameter of 1.0 μm.
%, Average particle size of 1.0 μm, Y ₂ O ₃ , Er ₂ O ₃ , Nd
Predetermined amounts of ₂ O ₃ , CeO ₂ and La ₂ O ₃ were added.

Paraffin wax was added as a binder to these raw material powders, mixed with a ball mill using IPA as a solvent, dried, granulated, and pressed. The molded body was degreased in a vacuum and fired in the atmosphere at a temperature shown in Table 1.

The crystal phase in this sintered body was identified by a powder X-ray diffraction method. Further, the content of the rare earth element-containing compound crystal phase was determined from a calibration curve prepared by previously performing a X-ray diffraction measurement of a mixture containing the rare earth element-containing compound crystal. The maximum particle size was determined by etching a mirror-polished surface, taking a micrograph, and setting the largest particle size among the 100 particles as the maximum particle size.

The element ratio between the rare earth element and aluminum was analyzed by X-ray fluorescence analysis of the sintered body, and the amount of impurity metal was analyzed by using ICP. The measurement of the alumina crystal phase ratio was calculated from the peak intensity using a calibration curve prepared in advance in X-ray diffraction.

The dielectric constant (ε ′) and dielectric loss (tan δ)
Is measured in the frequency range of 0.4 MHz to 10 GHz,
The maximum value is described. The relative density is determined by first determining the bulk density from the Archimedes method, then crushing the sintered body
Calculated by comparing with the true density obtained by the helium substitution method based on 1616.

Regarding the etching rate, fluorine and chlorine
Of etching rate when exposed to system plasma
did. The evaluation method is as follows.
A test piece with a thickness of 1 mm and a thickness of 1 mm
Mirror (reactive)
・ Ion etching) Fluorine using C
F _Four, Chlorine is Cl_TwoAt a gas flow rate of 100 sccm
Ching pressure 5Pa, RF output 1.0W / cm^TwoUnder the conditions
Etching was performed for 5 hours. Etching rate before test
It was calculated from the later weight change.

The presence or absence of particles was determined by processing each ceramic into a disk having a diameter of 8 inches and a thickness of 2 mm, polishing one side of the disk with a mirror surface and performing plasma etching. Then, an 8-inch Si virgin wafer was brought into contact with the etched surface. Irregularities on the contact surface of the Si wafer were detected by laser scattering, and the number of particles of 0.3 μm or more was counted by a particle counter.

[0040]

[Table 1]

In the sample of the present invention, the etching rate was 5 nm.
/ Min or less, the number of particles is 30 or less, and the corrosiveness is high, and the generation of particles is small. That is, Y and A
1 of the present invention having garnet as the main crystal. 2
Sample Nos. To 6 have an etching rate of 4.2 nm / min or less, the number of particles is 30 or less, and have a garnet of Er and Al as a main crystal. In Nos. 9 to 11, the etching rate was 3.1 nm / min or less and the number of particles was 28 or less.

The sample No. 1 of the present invention mainly containing melilite crystals was used. 12 and 13 have an etching rate of 2.4 nm /
min or less, the number of particles is 26 or less, and the sample No. of the present invention mainly composed of perovskite crystals is used. Fifteen, one
Sample No. 6 had an etching rate of 2.6 nm / min or less and the number of particles was 23 or less.

Further, the sample No. 1 of the present invention using Yb, Ce and La as rare earth elements. Nos. 18 to 20 have an etching rate of 2.9 nm / min or less and a particle number of 23.
Or less. In addition, Sample No. of the present invention in which Y and Yb were simultaneously used as rare earth elements. In No. 21, the etching rate was 2.4 nm / min or less and the number of particles was 20 or less.

On the other hand, the relative density is less than 98%, so that the dielectric constant exceeds 13, and the dielectric loss (tan δ) is 5 × 1.
Sample No. larger than ^{0-4 is} out of the range of the present invention. 1, 14
Has an etching rate of 5.5 nm / min or more and a particle number of 41 or more.

The dielectric constant exceeds 13, and the dielectric loss (t
sample No. an.delta.) larger than 5.times.10.sup.- ⁴ outside the range of the present invention. 8 has an etching rate of 5.6 nm / min or more,
The number of particles was 48.

Further, in Sample No. having a maximum particle size exceeding 10 μm. 7 has etching rates of 3.0 and 4.1 nm /
min, but the number of particles was as large as 45 and 52. Further, in sample no. 17 is an etching rate of 6.8 nm / min.
As described above, the number of particles was 50 or more.

[0047]

According to the corrosion-resistant member of the present invention, the amount of corrosion can be reduced by forming a composite oxide of aluminum and a rare earth, so that the amount of material deposited on the wall surface and the jig surface due to evaporation of the material is reduced, and the life is shortened. The length can be increased, the cleaning interval can be extended, and generation of particles can be suppressed.

Claims (7)

[Claims] 1. A sintered body mainly containing a composite oxide of Al and a rare earth element, wherein the sintered body contains Al as a metal component and at least one of rare earth elements, and other than Al and the rare earth element. The metal element is 500 ppm or less, the relative density is 98% or more, and the maximum particle size of the crystal grains of the main crystal phase is 10 μm or less, and the frequency is 0.4 MHz to
A corrosion resistant member having a dielectric constant of 13 or less and a dielectric loss of 5 × 10 ⁻⁴ or less in a range of 10 GHz. 2. The corrosion-resistant member according to claim 1, wherein the composite oxide is mainly composed of a garnet-type crystal and further contains a perovskite-type crystal and / or a rare-earth oxide crystal. 3. The method according to claim 1, wherein the alumina crystal particles are 1% by volume or less of the total amount, and the atomic ratio represented by RE / Al of the rare earth element (RE) to the aluminum element (Al) is from 0.6 to 0.6.
The corrosion resistant member according to claim 2, wherein the ratio is 0.7. 4. The corrosion-resistant member according to claim 1, wherein said composite oxide is mainly composed of a perovskite crystal and further contains a melilite crystal and / or a rare earth oxide crystal. 5. The method according to claim 1, wherein the content of the alumina crystal particles is 1% by volume or less based on the total amount, and the atomic ratio represented by RE / Al of the rare earth element (RE) to the aluminum element (Al) is 0.67 to less.
The corrosion-resistant member according to claim 4, wherein the ratio is 1.7. 6. The corrosion-resistant member according to claim 1, wherein said composite oxide is mainly composed of a melilite type crystal and further contains a perovskite type crystal and / or a rare earth oxide crystal. 7. The method according to claim 1, wherein the alumina crystal particles are 1% by volume or less of the total amount, and the atomic ratio represented by RE / Al of the rare earth element (RE) to the aluminum element (Al) is 1.6 or more. The corrosion-resistant member according to claim 6, wherein