JP2003095735A - Plasma resisting member, and production method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma resistant member which sufficiently withstands low-pressure, high-density plasma exposure, and to provide a production method therefor. SOLUTION: The plasma resistant member substantially consists of a yttrium garnet aluminate sintered compact, and, the ratio of unreacted alumina parts (alumina colonies) in the sintered compact structure is <=5% per unit volume, and, if required, the dimensions of the alumina colonies are <=5 μm. The production process contains a stage where yttrium garnet aluminate based powder prepared by a coprecipitation method is compacted, and a stage where the compact is heat-treated at 1,400 to 1,900 deg.C under a reduced pressure.

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 exhibiting excellent plasma resistance in a halogen-based corrosive gas atmosphere and a method for manufacturing the same.

[0002]

2. Description of the Related Art In a manufacturing process of a semiconductor device or a liquid crystal display device, an etching device or a sputtering device for finely processing a semiconductor wafer or a CVD device for forming a film on a semiconductor wafer or the like is used. Then, in these manufacturing apparatuses, a structure including a plasma generation mechanism is adopted for the purpose of high integration of the workpiece. For example, an etching apparatus using electron cyclotron resonance, which has a microwave generation chamber 1 and a processing chamber 2 as shown in FIG. 1, is known.

Here, the microwave generation chamber 1 and the processing chamber 2 are separated by a microwave introduction window 3, and a coil 4 for forming a magnetic field is arranged on the outer periphery of the processing chamber 2. . Further, the processing chamber 2 has a gas supply port 5 for supplying an etching gas, a gas exhaust port 6 for evacuating the inside of the processing chamber 2, and a monitoring window 7 for monitoring the inside of the processing chamber 2. On the other hand, in the processing chamber 2, there is installed a support / mounting table 9 for directly supporting the workpiece 8 such as a semiconductor wafer or via a susceptor (not shown).

Then, the etching process by this etching apparatus is performed as follows. That is, for example, the semiconductor wafer 8 is placed on the surface of the support / mounting table 9, the inside of the processing chamber 2 is evacuated, and then the highly reactive etching gas is supplied. On the other hand, microwaves are introduced into the processing chamber 2 from the microwave generation chamber 1 through the microwave introduction window 3, and the coil 4 is energized to generate a magnetic field, thereby generating high-density plasma. By this plasma energy, the etching gas is decomposed into an atomic state, and the surface of the semiconductor wafer 8 is etched.

By the way, in this type of manufacturing apparatus, a chlorine-based gas (for example, boron chloride (BC) is used as an etching gas.
1) or the like, or a corrosive gas such as a fluorine-based gas (for example, fluorocarbon (CF ₄ ), etc.). Therefore, components such as the inner wall portion of the processing chamber 2, the monitoring window 7, the microwave introduction window 3, and the support / mounting table 9 are exposed to plasma in a corrosive gas atmosphere, and thus plasma resistance is required. . In response to such demands, alumina-based sintered bodies, silicon nitride-based sintered bodies, aluminum nitride-based sintered bodies and the like are used as the plasma resistant member.

[0006]

However, the plasma resistant members such as the above-mentioned alumina-based sintered body, silicon nitride-based sintered body, and aluminum nitride-based sintered body are gradually exposed to plasma in a corrosive gas atmosphere. Corrosion progresses and the crystal grains forming the surface are detached, resulting in so-called particle contamination. Further, for example, in the case of an alumina-based sintered body or an aluminum nitride-based sintered body, aluminum fluoride is generated by the reaction with the fluorine-based plasma and is deposited on the weak plasma region in the apparatus chamber.

Since the deposits are peeled off to cause particle contamination, it is necessary to clean the inside of the chamber in order to avoid the contamination, the frequency of maintenance work is increased, and productivity is adversely affected. That is, the detached particles adhere to the semiconductor wafer 8 and the support / mounting table 9 and adversely affect the etching accuracy and the like, and the performance and reliability of the semiconductor are easily impaired. Note that the consumption of the constituent members in the chamber progresses due to, for example, repeated generation of fluoride by the reaction with fluorine-based plasma and decomposition / scattering of the generated fluoride. Therefore, the rate of progress of decomposition / scattering of reaction products greatly affects the corrosion resistance to plasma.

Further, even in the CVD apparatus, since it is exposed to a fluorine-based gas such as fluorine nitride (NF ₃ ) in plasma during cleaning, it is necessary to have corrosion resistance.

To solve the above-mentioned problem of corrosion resistance, a plasma resistant member made of a yttrium aluminate garnet (so-called YAG) sintered body has been proposed (for example, Japanese Patent Laid-Open No. HEI-1).
0-45461, JP-A-10-236871). That is, the surface exposed to plasma in a halogen-based corrosive gas atmosphere is formed of a sintered body mainly composed of a complex oxide such as spinel, cordierite, or yttrium aluminate garnet having a porosity of 3% or less, and A plasma resistant member having a center line average roughness (Ra) of 1 μm or less is known.

By the way, the yttrium aluminate garnet-based sintered body is usually prepared by mixing alumina powder and yttria powder in equivalent amounts and heat-treating at a temperature of around 1300 ° C. to produce yttrium aluminate garnet by a solid-phase reaction. After that, it is obtained by molding and sintering the raw material powder prepared by crushing this. When the pulverized / prepared powder of yttrium aluminate garnet produced by the solid phase reaction is used as the material, unreacted alumina part (alumina colony) is mixed in the structure of the yttrium aluminate garnet-based sintered body. There is.

The present inventors diligently studied the relationship between the plasma resistance and the amount of unreacted alumina portion (alumina colony) per unit volume in the structure of the yttrium aluminate garnet type sintered body. As a result, it was found that the content of alumina colonies in the sintered structure affects the plasma resistance. That is, the alumina colonies in the sintered body structure are selectively consumed when exposed to plasma, and crystal particles are likely to drop off due to this selective consumption, resulting in particle contamination.

However, if the amount of alumina colonies in the sintered structure is 5% or less per unit volume, and if the size of the alumina colonies is 5 μm or less, the above-mentioned selective consumption is remarkable. Reduced / suppressed. That is, it was confirmed that when the amount of alumina colonies was suppressed to be low, generation of particle contamination was easily prevented or avoided, and excellent plasma resistance was exhibited. Further, the yttrium aluminate garnet-based sinter having a reduced amount of alumina colonies in the sintered body structure is easier and more productive when the yttrium aluminate garnet-based powder prepared by the coprecipitation method is used as the raw material powder. It was found that it can be manufactured.

[0013]

According to the invention of claim 1, an unreacted alumina portion (alumina colony) in the sintered body structure is substantially composed of a yttrium aluminate garnet type sintered body, and the unreacted alumina portion is 5 per unit volume. % Or less, the plasma resistant member.

The invention of claim 2 is characterized in that, in the plasma resistant member according to claim 1, the unreacted alumina portion (alumina colony) has a size of 5 μm or less.

A third aspect of the present invention is a step of molding the yttrium aluminate garnet-based powder prepared by the coprecipitation method, and 1400 to 1900 ° C. in a reduced pressure atmosphere of the molded body.
And a step of performing heat treatment at a temperature of 1.

In the inventions of claims 1 and 2, in the yttrium aluminate garnet-based sintered body, the composition ratio of the unreacted alumina portion (alumina colony) dispersed and contained in the sintered body tissue is 5% per unit volume. Hereafter, it is preferably 3% or less per unit volume. Here, if the composition ratio of the alumina colonies exceeds 5% per unit volume, the selective consumption when exposed to plasma becomes relatively large, and the required excellent plasma resistance cannot be obtained. That is,
When the composition ratio of the alumina colony exceeds 5% per unit volume, the selective consumption of the alumina colony easily causes the crystal grains constituting the sintered body to fall off, resulting in a particle contamination problem. , 5% or less per unit volume, preferably 3% or less per unit volume.

In the inventions of claims 1 and 2, the size (dispersion / particle diameter) of the unreacted alumina portion (alumina colony) dispersed / contained in the structure of the yttrium aluminate garnet-based sintered body is 5 μm or less. Is desirable. That is, when the dispersion / content of the alumina colony is 5% or less per unit volume, and the dispersion / particle size of the alumina colony is 5 μm or less, the selective wear of the alumina colony is further reduced. As a result, the surface roughness can be effectively avoided. Therefore, it is possible to effectively suppress the dropout / occurrence of the crystal particles that make up the sintered body.
As a result, the generation of sudden dust can be avoided, and the particle contamination problem can be solved more easily.

The plasma resistant member according to the inventions of claims 1 and 2 can be easily manufactured by the method according to the invention of claim 3, for example. That is, first, a precipitate containing yttrium and aluminum is produced by a coprecipitation method from an acidic aqueous solution containing equivalent amounts of yttrium and aluminum ions. Next, the generated precipitate is calcined in an oxidizing atmosphere at a temperature of about 1300 ° C. and then pulverized to prepare yttrium aluminate garnet powder.

A binder resin and a medium liquid are added to the raw material powder thus obtained, and a slurry is prepared by, for example, a rotary ball mill. Further, the prepared slurry is granulated by, for example, a dry spray method, molded by a hydrostatic pressing method or the like, and the molded body is subjected to calcination / degreasing treatment under reduced pressure. Here, the raw material powder may be molded by molding means such as mold molding, extrusion molding, injection molding, and casting molding, instead of being performed by isostatic pressing. Then, by subjecting the molded body to a vacuum sintering treatment, the unreacted alumina part (alumina colony) dispersed and contained in the structure of the sintered body is 5% per unit volume.
In the following, a yttrium aluminate garnet-based sinter having an alumina colony size of 5 μm or less can be obtained.

The components used for the coprecipitation of yttrium and aluminum, in other words, the compounds that produce yttrium ions and the compounds that produce aluminum ions when made into an acidic aqueous solution include the following compounds. That is, as a yttrium ion source,
For example, yttrium nitrate, etc. can be mentioned.
One kind or a mixed system of two or more kinds may be used. Further, examples of the aluminum ion source include aluminum sulfate and the like, and these may be one kind or a mixed system of two or more kinds.

According to the first and second aspects of the invention, the yttrium aluminate garnet-based sintered body is selectively consumed when exposed to plasma, and the cause of dropping of crystal grains or particle contamination is largely removed or reduced. ing. In other words, alumina colonies that are dispersed and contained in the structure of the sintered body and are selectively consumed when exposed to plasma and crystal particles fall off, causing particle contamination due to this drop, are 5% or less per unit volume, and If necessary, the size is regulated to 5 μm or less. Due to the reduction and regulation of the amount of alumina colonies, excellent plasma resistance that does not cause particle contamination is exhibited.

Therefore, while suppressing an increase in the manufacturing cost of the manufacturing apparatus or the semiconductor, it is possible to effectively contribute to the manufacturing and processing of a semiconductor having high performance and reliability without adversely affecting the quality and accuracy of film formation. To do.

According to the third aspect of the present invention, it is possible to provide a plasma resistant member having improved and improved plasma resistance in good yield and in mass production.

[0024]

Embodiments of the present invention will be described below.

Yttrium compounds that produce yttrium ions in an acidic aqueous solution (eg, yttrium nitrate)
And an aluminum compound (for example, aluminum sulfate) which similarly produces aluminum ions in the acidic aqueous solution as raw materials, to prepare an acidic aqueous solution containing yttrium ions and aluminum ions in an equivalent ratio. Then
A yttrium-aluminum-based coprecipitate based on yttrium ions and aluminum ions is produced by a coprecipitation method in which the prepared acidic aqueous solution is appropriately heated and stirred. Then, the co-precipitated product is collected by filtration, calcined in the air at a temperature of about 1300 ° C. for 2 hours, then cooled and pulverized to obtain yttrium aluminate garnet powder.

Next, an appropriate amount of ion-exchanged water and 2% by weight of polyvinyl alcohol are added to 100% by weight of the yttrium aluminate garnet powder, and the mixture is stirred and mixed to prepare a slurry. Then, the prepared slurry is granulated with a spray dryer, and the resulting granulated powder is subjected to isostatic pressing (CIP press) at 9.807 × 10 ⁵ MP.
It was molded under a pressure of a (1000 kgf / cm ² ) to obtain a molded body having a thickness of 10 mm, a width of 100 mm and a length of 100 mm.

For the above molded body, 1.33 Pa (0.
Sintering was performed at a temperature of 1750 ° C. in a vacuum (01 Torr) or less (under reduced pressure) to obtain a yttrium aluminate garnet-based sintered body. When the amount of alumina colonies in the structure of the sintered body of this sintered body was analyzed, the content was 1% or less per unit volume, and the size was 1 μm or less.

Further, a test piece having a thickness of 2 mm and a size of 10 × 10 mm was cut out from the yttrium aluminate garnet-based sintered body and attached to a parallel plate type RIE apparatus, and a frequency of 13.56 MHz, a high frequency source of 500 W, a high frequency bias of 300 W, CF ₄ / O ₂ / Ar = 40: 10:
20 under the conditions of 50, 5 × 133 Pa (5 mTorr)
A time plasma exposure test was performed to measure the etching rate (angstrom / hour) and observe the surface morphology with a scanning electron microscope (SEM). as a result,
The etching rate was about 120 Å / hour, and the surface morphology exhibited a flat surface before and after plasma exposure, and no difference was observed.

On the other hand, as a comparative example, a case where yttrium aluminate garnet prepared by a so-called solid-phase reaction method is used as a raw material powder will be exemplified. In this comparative example, first,
Yttria powder having a purity of 99.9% and an average particle diameter of 0.5 μm and alumina powder having a purity of 99.9% and an average particle diameter of 0.5 μm are prepared. Then, in a molar ratio, yttria 3:
Alumina 5 was mixed and the mixture was mixed at 1400 ° C.
It heat-processed at the temperature of (calcination), the yttrium aluminate garnet was produced | generated by the solid phase reaction, this yttrium aluminate garnet was grind | pulverized, and the raw material powder was prepared.

Thereafter, 100% by weight of this raw material powder was added to
However, an appropriate amount of ion-exchanged water and polyvinyl alcohol double
Amount% is added, stirred and mixed to prepare a slurry. Next
Granulate the prepared slurry with a spray dryer.
Then, the obtained granulated powder is subjected to isostatic pressing (CIP press).
And 9.807 × 10⁵MPa (1000 kgf / cm
^Two ) Pressure, thickness 10 mm, width 100 mm, length
A molded body having a size of 100 mm was obtained.

The above molded body was subjected to calcination / degreasing treatment at a temperature of 900 ° C., and then 1.33 Pa (0.01 m)
Torr) Sintering and firing treatment was performed at a temperature of 1750 ° C. in a vacuum of not more than Torr to obtain a yttrium aluminate garnet-based sintered body. When the amount of alumina colonies in the sintered body structure of this sintered body was analyzed, the content was 6% per unit volume, and the size was 3 μm.

Further, a test piece having a thickness of 2 mm and a size of 10 × 10 mm was cut out from the yttrium aluminate garnet-based sintered body and attached to a parallel plate type RIE apparatus, and a frequency of 13.56 MHz, a high frequency source of 500 W, and a high frequency bias of 300 W, CF ₄ / O ₂ / Ar = 40: 10:
20 under the conditions of 50, 5 × 133 Pa (5 mTorr)
A time plasma exposure test was performed to measure the etching rate (angstrom / hour) and observe the surface morphology with a scanning electron microscope (SEM). as a result,
The etching rate is about 170 Å / hour, and the surface morphology is 1 to 2 μm before and after plasma exposure.
The difference in the depressions was confirmed, and the surface was rough overall.

As described above, the plasma-resistant member according to the example is significantly more damaged by plasma under corrosive gas and particles such as aluminum fluoride are generated, as compared with the plasma-resistant member according to the comparative example. It is suppressed. In other words, when the plasma resistance is evaluated in terms of etching rate, it is about 1.5 times that of the comparative example, which is advantageous not only in terms of maintenance but also in highly accurate processing in semiconductor manufacturing processes. However, it is possible to eliminate the possibility of adversely affecting the work piece.

The present invention is not limited to the above embodiments, but various modifications can be made without departing from the spirit of the invention. For example, the compounds as the yttrium ion source and the aluminum ion source may be selected combinations of other compounds, and can be appropriately changed within a permissible range such as a vacuum (reduced pressure) sintering temperature and a sintering temperature in the air atmosphere.

[0035]

According to the first and second aspects of the present invention, there is provided a plasma resistant member which is a yttrium aluminate garnet type sintered body and which is excellent in plasma resistance. That is, in the structure of the region exposed to the plasma containing corrosive gas, it functions as a member having excellent durability, which contributes to a longer life of the semiconductor manufacturing apparatus. Also,
Since there is no possibility of particle contamination, it is possible to improve the reliability of the semiconductor and the yield.

According to the third aspect of the present invention, the plasma resistance is excellent, and the plasma resistance member suitable for the semiconductor manufacturing apparatus can be provided in good yield and in mass production.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of a plasma etching apparatus.

[Explanation of symbols]

1 ... Microwave generation chamber 2 ... Processing room 3 ... Microwave introduction window 4 ... Magnetic field forming coil 5: Gas supply port 6 ... Gas outlet 7 ... Monitoring window 8 ... Semiconductor wafer 9 ... Semiconductor wafer support / mounting table

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akira Miyazaki             30 Soya, Hadano City, Kanagawa Prefecture             Kusu Co., Ltd. Development Laboratory (72) Inventor Mitsuhiro Fujita             30 Soya, Hadano City, Kanagawa Prefecture             Kusu Co., Ltd. Development Laboratory (72) Inventor Shunichi Suzuki             30 Soya, Hadano City, Kanagawa Prefecture             Kusu Co., Ltd. Development Laboratory (72) Inventor Shuichi Saito             33, Shinisogo-cho, Isogo-ku, Yokohama-shi, Kanagawa             Inside the Toshiba Production Technology Center (72) Inventor Eriko Nishimura             33, Shinisogo-cho, Isogo-ku, Yokohama-shi, Kanagawa             Inside the Toshiba Production Technology Center F-term (reference) 4G031 AA08 AA29 BA01 BA21 CA07                       GA01 GA03 GA08 GA11                 4G075 AA24 AA30 AA42 AA53 BC02                       BC04 BC06 BD14 CA47 DA02                       FB04 FC09                 5F004 AA15 BA20 BB29 BD04 DA01                       DA11

Claims (3)

[Claims] 1. An unreacted alumina part (alumina colony) in a sintered body structure, which is substantially composed of a yttrium aluminate garnet-based sintered body, is 5% per unit volume.
The following is a plasma resistant member. 2. The plasma resistant member according to claim 1, wherein the unreacted alumina portion (alumina colony) has a size of 5 μm or less. 3. A method comprising molding a yttrium aluminate garnet-based powder prepared by a co-precipitation method, and heat-treating the molded body at a temperature of 1400 to 1900 ° C. in a reduced pressure atmosphere. Method for manufacturing plasma resistant member.