JPH11228172A - Plasma corrosion resistant glass and device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide glass superior in high-frequency transmittance, airtightness, as a container using to a plasma generation part, and also superior in corrosion resistance for plasma gas, and a semiconductor production device or a liquid crystal production device using it. SOLUTION: In the glass whose glass forming substance consists essentially of SiO2 , Al is incorporated 0.05-10 atomic % or 0.01-10 atomic % Al and less than 10 atomic % N (not include 0) are incorporated. An aluminum oxide concentrated layer is preferred to be formed on a glass surface, and the contents of alkali metal and/or transition metal are preferred to be less than 90 ppm in the total quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma corrosion-resistant glass used in a part for generating plasma in a semiconductor manufacturing apparatus or a liquid crystal manufacturing apparatus, and a semiconductor manufacturing apparatus or a liquid crystal manufacturing apparatus using the plasma corrosion-resistant glass. is there.

[0002]

2. Description of the Related Art In recent years, a plasma reactor using plasma has been frequently used for CVD processing, etching or resist processing in the production of semiconductors, liquid crystals and thin films. here,
In general, plasma is generated by applying a high frequency or microwave from outside to a plasma generating gas to generate plasma. Therefore, a material having excellent high-frequency permeability and vacuum tightness is used for the plasma generating portion of the plasma reaction vessel, specifically, for the high-frequency introduction portion and the output portion.

As materials having excellent high-frequency transmittance and vacuum tightness, quartz glass, alumina ceramics, single-crystal alumina (sapphire), and aluminum nitride (AlN), which are dense bodies having a low dielectric constant and a low dielectric loss, can be considered.

However, alumina ceramics and single-crystal alumina (sapphire) have poor impact resistance at high temperatures,
The mechanical strength required when generating plasma is not sufficient. In addition, it is inferior to quartz glass in terms of high frequency characteristics. In addition, aluminum nitride (AlN) has a problem that the surface area exposed to plasma is increased due to poor surface smoothness, and the aluminum nitride (AlN) is easily corroded. In other words, even when used in a plasma generating portion, the generated ion plasma, high-velocity particles, or bombardment of electrons or a chemical reaction due to active species in a gas phase may occur. For this reason, in addition to the high-frequency permeability and the vacuum tightness described above, the container for the plasma generating portion is required to have resistance to corrosion by plasma gas (hereinafter, referred to as “plasma corrosion resistance”).

[0005] Among the above materials, quartz glass is excellent in high-frequency characteristics and heat resistance, but has insufficient plasma corrosion resistance. In particular, in a fluorine plasma, the following reaction occurs with SiO ₂ that is a constituent material of quartz glass to generate SiF _4, and the generated SiF ₄ has a melting point of −90.2 ° C. and a boiling point of −86 ° C. The gas phase is stable in the process. Therefore, SiF ₄ generated by the reaction evaporates immediately, and the following reaction with SiO ₂ newly appearing on the surface progresses more and more, so that corrosion by the fluorine-based plasma proceeds. SiO ₂ + 4F → SiF ₄ ↑ + O ₂ ↑ The progress of such a reaction not only shortens the life of the quartz glass, but also causes the initially transparent quartz glass to gradually become white due to the continued generation of SiF _4. There is also a problem that light transmittance is reduced.

The surface of quartz glass is oxynitrided or the surface of quartz glass is silicon nitride (Si) so as to have the same or higher heat resistance as quartz glass and excellent plasma corrosion resistance while utilizing the characteristics of quartz glass. ₃ N ₄₎ to form a layer has been proposed.

For example, JP-A-60-246281, JP-A-60-246281
In Japanese Patent Application Laid-Open No. 4-59633, a method of treating a quartz material in an ammonia atmosphere is disclosed in JP-A-7-53242 and JP-A-8-53242.
Japanese Patent No. 222575 proposes a method of oxidizing and nitriding the surface of quartz glass or forming a silicon nitride coating layer on the surface of quartz glass using a heat treatment using an ammonia gas, a carbon source, and a hydrocarbon gas. In addition, JP-A-62-963
No. 49 discloses that silicon tetrachloride (Si
There has been proposed a quartz glass reaction tube for semiconductor heat treatment in which a dense silicon nitride layer is formed on the surface of quartz glass using a CVD method in which Cl ₄ ) and ammonia gas (NH ₃ ) are passed under vacuum.

[0008]

However, although the silicon nitride layer has better corrosion resistance than quartz glass, its surface is also etched in fluorine plasma, and the plasma corrosion resistance is still at a level that is satisfactory as a material for a plasma reactor. Absent.

The present invention has been made in view of such circumstances, and it is an object of the present invention as a material for a plasma reaction vessel used in a semiconductor manufacturing process or the like, which is particularly excellent in corrosion resistance to a fluorine-based plasma gas. To provide a plasma corrosion resistant glass.

[0010]

That is, in the plasma corrosion resistant glass according to the first invention, the main constituent of the glass forming material is S.
In the glass is iO _2, aluminum 0.05
-10 at%.

[0011] The plasma corrosion-resistant glass according to the second invention comprises:
In a glass in which the main component of the glass-forming substance is SiO ₂ , 0.01 to 10 atomic% of aluminum and 1% of nitrogen are contained.
0 atomic% or less (not including 0) is contained.

Preferably, the plasma corrosion resistant glass has a thickened layer of aluminum oxide formed thereon.
The content of alkali metal and / or transition metal is 9 in total.
It is preferably 0 ppm or less.

Further, a semiconductor manufacturing apparatus or a liquid crystal manufacturing apparatus of the present invention is characterized by using the above-mentioned plasma corrosion resistant glass of the present invention.

[0014]

Embodiments of the present invention will be described below. First, the plasma corrosion resistant glass according to the first invention is characterized in that a glass mainly composed of SiO ₂ contains 0.05 to 10 atomic% of aluminum.

[0015] By using quartz glass as a main component, high-frequency transmittance and vacuum airtightness required for a plasma generating portion and a plasma sealing portion can be satisfied.

When aluminum atoms in a solid solution state in SiO ₂ are exposed to a plasma gas, in particular, oxygen plasma, the aluminum atoms are concentrated in the surface layer, and an aluminum oxide concentrated layer is formed on the glass surface. Here, since aluminum oxide (Al ₂ O ₃ ) has a large negative free energy value in the reaction with atomic fluorine, the reaction can proceed thermodynamically, but the reaction speed is SiO ₂ and F Since the reaction speed is slower than the reaction speed, the reaction hardly proceeds. Therefore, by forming an aluminum oxide (Al ₂ O ₃ ) layer on the glass surface, SiO ₂ which is a glass constituent substance is formed.
And the reaction of fluorine with the plasma. Even if aluminum oxide reacts with fluorine to produce aluminum fluoride (AlF ₃ ), aluminum fluoride is a sublimable substance having a boiling point of 1200 ° C. or more and continues to exist on the quartz glass surface. Therefore, new corrosion can be prevented from progressing.

The concentrated aluminum oxide layer formed on the surface of the plasma corrosion resistant glass according to the present invention is made of SiO ₂
Since it is formed by concentrating the surface layer portion of Al dissolved therein, the glass substrate is far more in comparison with the case where the quartz glass surface has an Al ₂ O ₃ coating film formed by a CVD method or the like. Because of the strong integration with the above, plasma corrosion resistance is also excellent.

The high corrosion resistant glass according to the first invention has an aluminum content of 0.05 to 10 atomic% of aluminum. If the content is less than 0.05 at%, formation of the aluminum oxide concentrated layer that completely covers the quartz glass surface becomes insufficient. On the other hand, when aluminum alone is dissolved in quartz glass mainly composed of SiO ₂ , a tetrahedral three-dimensional structure of [SiO ₄ ] is formed with a part of Si atoms being replaced by aluminum. Therefore, an oxygen atom that does not form a cross-link is generated (this acid atom is referred to as a “non-cross-linked oxygen atom”). In FIG. 1, (a) shows a quartz glass state, in which oxygen atoms are arranged at the vertices of a tetrahedron with Si as a center, and Si—O—Si cross-links with Si atoms of an adjacent tetrahedron. The held [SiO ₄ ] tetrahedral three-dimensional array is randomly formed. On the other hand, FIG.
In (b), as a result of Al being incorporated into the glass skeleton network structure, the positive charge is insufficient, and non-crosslinked oxygen atoms in a state where the three-dimensional network structure is cut off are present.

As described above, when the content of aluminum is too large, the reactivity of the glass becomes high (in other words, general corrosion resistance including plasma corrosion resistance becomes low) with an increase in non-crosslinked oxygen atoms. Also, as the aluminum content increases, the thickness of the Al ₂ O ₃ enriched layer increases, resulting in a decrease in high-frequency transmittance. Therefore, the aluminum content needs to be 10 atomic% or less. Next, the corrosion-resistant glass according to the second invention will be described.

The corrosion-resistant glass according to the second invention is a glass in which the glass-forming substance is mainly SiO ₂ , wherein aluminum is 0.01 to 10 atomic% and nitrogen is 10 atomic%.
The following (not including 0) is contained.

As described in the first aspect of the present invention, by containing aluminum, an aluminum oxide-enriched layer having excellent corrosion resistance can be formed on the glass surface, but the number of non-crosslinked oxygen atoms also increases. In the second invention, by containing nitrogen, a decrease in corrosion resistance due to the cutting action of aluminum is prevented. That is, as shown in FIG. 2, a part of oxygen is replaced by nitrogen having three bonds to form a Si = N bond, and Si-Al-ON (Sialon)
, The binding energy of the entire system is increased, so that the corrosion resistance to plasma is enhanced. By compensating for the lack of positive charges generated by adding Al atoms and reducing non-bridging oxygen atoms, a decrease in corrosion resistance is prevented.

The content ratio of aluminum according to the second invention is 0.01 to 10 atomic%. By adding nitrogen, S
Since the corrosion resistance of the entire glass can be improved by forming the i-Al-ON (Sialon) structure, even if the glass surface does not contain a sufficient amount of aluminum to cover the glass surface with the aluminum oxide concentrated layer. This is because corrosion resistance can be exhibited. On the other hand, even if the content exceeds 10 atomic%, the effect of adding aluminum is saturated and the effect of improving the corrosion resistance is not obtained, and crystals such as AlN are precipitated due to the increase of the amount of aluminum, and quartz is added. This is because it causes a decrease in the high-frequency transmittance inherent to glass.

The nitrogen content is 10 atomic% or less (excluding 0) and may be appropriately selected according to the aluminum content. Non-bridging oxygen atoms can be reduced by adding aluminum by adding nitrogen, but if the nitrogen content is too high, crystals such as SiN and AlN are precipitated.

Further, in the first and second aspects of the present invention, the content of the alkali metal and / or the transition metal is preferably
The total amount is preferably 90 ppm or less. Alkali metals and / or transition metals cause high-frequency characteristics to deteriorate. Therefore, by reducing the content thereof, a plasma generating gas is sealed inside, and plasma is generated by transmitting high frequency from the outside to generate plasma. It is suitably used as a generating container.

Therefore, in the semiconductor manufacturing apparatus or the liquid crystal manufacturing apparatus according to the present invention, since the plasma generating portion is made of the above-described material of the present invention having excellent plasma corrosion resistance, high-frequency transmittance, and vacuum tightness, the plasma generating portion is excellent. The etching and the resist process can be used accurately for a long period of time.

[0026]

[Example] [Effect of aluminum content] SiO ₂ powder,
Al ₂ O ₃ powder was prepared and heat-treated at 1700 to 1900 ° C. in an inert atmosphere or a reducing atmosphere to produce quartz glass whose aluminum content was adjusted as shown in Table 1.

The produced quartz glass is subjected to a high frequency plasma reactor.
Put in the actor, CF_Four / O_TwoIn mixed gas or SF₆
 Plasma etching was performed for 100 hours in a gas. Plastic
Measure the amount of weight loss before and after Zuma etching and etch
The reduction ratio (%) with respect to the previous weight was determined. The result
Table 1 and FIG. 3 (CF_Four / O_Two Plasma), FIG. 4 (SF ₆ 
Plasma).

[0028]

[Table 1]

As can be seen from Table 1 and FIGS. 3 and 4, when the addition amount of aluminum is 0.05 atomic% or more, the weight reduction amount is drastically reduced to 0.003 to 0.01%, and the durability against plasma is increased. However, when the content exceeds 10 atomic%, the amount of non-crosslinked oxygen atoms increases, so that corrosion by fluorine plasma progresses and the weight loss increases.

[Effect of Nitrogen Content] SiO ₂ powder, Al ₂
O ₃ powder, Si ₃ O ₄ powder, and AlN powder were mixed and heat-treated at 1700 to 1900 ° C. under an inert atmosphere or a reducing atmosphere to produce quartz glass whose aluminum content was adjusted as shown in Table 2. . Put the produced quartz glass in a high-frequency plasma reactor, the same conditions as in the experiment,
That is, plasma etching was performed for 100 hours in a CF ₄ / O ₂ mixed gas. The weight loss before and after the plasma etching was measured, and the reduction ratio (%) to the weight before the etching was determined. The results are shown in Table 2 and FIG.

[0031]

[Table 2]

Comparing the weight loss with respect to the CF ₄ / O ₂ mixed gas plasma in Table 2 and Table 1, the weight loss differs depending on the N addition amount even when the Al addition amount is the same, and the N addition amount is adjusted. This shows that the weight loss can be reduced as compared with the case of using Al alone.

The relationship of the weight loss to the nitrogen addition is:
As shown in FIG. The reduction may be 0.01% or less (indicated by "●" in FIG. 5), and if it exceeds 0.01%, the plasma corrosion resistance is insufficient (indicated by "x" in FIG. 5). FIG.
From this it can be seen that the weight loss is also related to the amount of N added.

Further, the results in Table 2 are shown in FIG. 6 as a relationship between the aluminum addition amount (horizontal axis) and the nitrogen addition amount (vertical axis).
To From FIG. 6, when the aluminum addition amount is in the range of 0.01 atomic% to 10 atomic% and the nitrogen addition amount is 10 atomic% or less, the weight loss is 0.01% or less. "), The amount of aluminum added was 10
If the amount exceeds 10 atomic% or the amount of added nitrogen exceeds 10 atomic%, the weight loss exceeds 0.01% (in FIG.
), The plasma corrosion resistance was insufficient.

[0035]

The corrosion-resistant glass of the present invention has excellent plasma corrosion resistance because the aluminum contained forms an aluminum oxide concentrated layer having excellent plasma corrosion resistance on the glass surface.

In a high corrosion-resistant glass containing nitrogen in a predetermined range together with aluminum, non-crosslinked oxygen atoms can be reduced by containing nitrogen, so that there is no general decrease in corrosion resistance due to the addition of aluminum.

Further, since the main body of the glass is made of quartz glass which is excellent in high-frequency transmittance and vacuum tightness, the content of the alkali metal and / or the fiber metal is set to a predetermined amount or less, so that the plasma generating portion is formed. It can be suitably used as a container material for.

[Brief description of the drawings]

FIG. 1 is a view for explaining a problem when aluminum is contained in quartz glass.

FIG. 2 is a diagram illustrating a sialon configuration.

FIG. 3 is a graph showing the relationship between the content of aluminum atoms in quartz glass and the amount of weight loss in CF ₄ / O ₂ mixed gas plasma.

FIG. 4 is a graph showing the relationship between the content of aluminum atoms in quartz glass and the weight loss in SF ₆ gas plasma.

FIG. 5 shows nitrogen atom content and CF ₄ /
5 is a graph showing a relationship with an amount of weight loss when plasma etching is performed using an O ₂ mixed gas.

FIG. 6 is a graph showing the relationship between the content of aluminum atoms and the content of nitrogen atoms in quartz glass and the plasma corrosion resistance to a CF ₄ / O ₂ mixed gas.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/22 511 H01L 21/22 511M 21/68 21/68 N

Claims (6)

[Claims] 1. A plasma corrosion resistant glass, wherein the glass forming substance is mainly SiO ₂ , wherein aluminum is contained in an amount of 0.05 to 10 atomic%. _2. A glass in which the main constituent of the glass-forming substance is SiO ₂ , wherein the glass contains 0.01 to 10 atomic% of aluminum and 10 atomic% or less (excluding 0) of nitrogen. Plasma corrosion resistant glass. 3. A plasma corrosion-resistant glass according to claim 1, wherein a concentrated layer of aluminum oxide is formed on the surface of the glass according to claim 1. 4. The plasma corrosion-resistant glass according to claim 1, wherein the content of the alkali metal and / or the transition metal is 90 ppm or less in total. 5. A semiconductor manufacturing apparatus using the plasma corrosion-resistant glass according to claim 1. 6. A liquid crystal manufacturing apparatus using the plasma corrosion-resistant glass according to claim 1.