JP2002137927A - Quartz glass superior in resistance to plasma corrosion and quartz glass jig and their manufacturing methods - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a quartz glass superior in the resistance to plasma corrosion, especially in the resistance to F based plasma gas, as a jig material for a plasma reaction used in semiconductor manufacturing and a quartz glass jig and their manufacturing methods. SOLUTION: The resistance to plasma corrosion of the quartz glass which contains a metal element is increased. The quantity of bubbles and foreign matter in the quartz glass is less than 100 mm2 as projected area per 100 cm3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a quartz glass and a quartz glass jig which are used in semiconductor production and have excellent plasma corrosion resistance, and a method for producing the same.

[0002]

2. Description of the Related Art In the manufacture of semiconductors, for example, in the manufacture of semiconductor wafers, the processing efficiency has been improved by using a plasma reactor in an etching process and the like in accordance with an increase in diameter in recent years.
For example, in a semiconductor wafer etching process,
An etching process using a plasma gas, for example, a fluorine (F) -based plasma gas is performed.

However, when a conventional quartz glass is placed in, for example, an F-based plasma gas atmosphere, Si
O ₂ and the F-based plasma gas react to generate SiF ₄ ,
This is because the boiling point is −86 ° C., so that it easily sublimates, the quartz glass corrodes a lot, and the thinning and surface roughening progress.
In a system plasma gas atmosphere, it was not suitable for use as a jig.

As described above, the conventional quartz glass has a serious problem in corrosion resistance, that is, plasma corrosion resistance in a plasma reaction in semiconductor production, particularly in an etching process using an F-based plasma gas. Therefore, a proposal has been made to improve the plasma corrosion resistance by coating the surface of a quartz glass member with aluminum or an aluminum compound (JP-A-9-9577).
No. 1, JP-A-9-95772, JP-A-10-1394
No. 80), and a plasma corrosion-resistant glass in which plasma corrosion resistance is improved by adding aluminum to quartz glass has been proposed (Japanese Unexamined Patent Publication No. Hei.
1-228172).

[0005]

The present inventor has been conducting various researches to further improve the plasma corrosion resistance of quartz glass. As one of the studies, a mixture of quartz glass powder and alumina powder in an amount of 5 wt% is used. The quartz glass was prepared by heating and melting under vacuum, and the plasma corrosion resistance was investigated. As a result, the etching rate was reduced by 40% to 50% as compared with the undoped quartz glass member.

However, microbubbles are observed inside and on the surface of the quartz glass body. In particular, in the surface portion, the difference between the corroded portion and the non-corroded portion becomes large, the surface roughness increases, and the microcrystalline portion is generated. As a result, peeling frequently occurs from the portion with time, and the generation of particles increases along with the formation of minute dents, and the particles adhere to the wafer surface, causing a problem such as an increase in wafer defects. In addition, since these bubbles and depressions promote the etching, even if the concentration of the doped metal is increased, the etching corrosion resistance was not relatively improved.

[0007] because the boiling point is 1290 ° C. of AlF ₃ that reacts with F based plasma gas, since it is much hotter than the SiF _4, while the SiF ₄ portion is a large amount of corrosion, AlF ₃ It is presumed that the portion has less sublimation on the surface and the difference in the etching amount has increased. Also, if the doped aluminum is locally concentrated, adjacent Si
Since the energy state is clearly different from that of the O ₂ portion, the balance is broken, and SiO ₂ is more easily transformed into a low-energy crystal state from that portion.

[0008] This crystal part is visually recognized as a fine white foreign substance. Since the crystal part formed near the surface has a different thermal expansion degree from that of quartz glass, it is easy to peel off due to a temperature change. In addition, since the locally concentrated metal element has a boiling point lower than that of SiO ₂ alone, it becomes a gas when SiO ₂ is melted and heated to form bubbles. The bubble portion near the surface is easily ruptured due to a change in temperature. All of these described above cause particles to be generated. In addition, since the etching rate tends to increase due to the concentration of the plasma gas due to bubbles and concave portions, the amount of etching of the entire quartz glass also increases, and the usable time decreases.

The present invention has been made on the basis of the above-mentioned findings. As a jig material for a plasma reaction used in the manufacture of semiconductors, quartz glass and quartz glass having excellent plasma corrosion resistance, in particular, corrosion resistance to an F-based plasma gas are provided. It is an object of the present invention to provide tools and methods for producing them.

[0010]

In order to solve the above-mentioned problems,
The quartz glass having excellent plasma corrosion resistance of the present invention is a quartz glass containing a metal element and having increased plasma corrosion resistance, and the content of bubbles and foreign substances in the quartz glass is 100 cm ^3.
The projection area per unit is less than 100 mm ² .

It is needless to say that the above-mentioned embodiment of the metal element includes a dope and / or a surface coat, but it is needless to say that the embodiment does not matter as long as the metal element is contained at a predetermined concentration.

If the above-mentioned content of bubbles and foreign matter in quartz glass is less than 100 mm ^{2 in} a projected area per 100 cm ³ , it is at a level that can be used as a general quartz glass member. Does not generate particles, but if it exceeds the above value,
Particle generation becomes large.

The types of the above metal elements are not limited to Al (aluminum) and aluminum compounds disclosed in the above proposals, and the boiling point of the fluoride of the metal element is higher than the boiling point of the fluoride of Si. Temperature is F
This is a condition that can be used for system plasma gas etching. For example, in addition to elements such as Ti, Zr, and Y, rare earth elements such as Sm having high etching corrosion resistance can be used. However, in the case of a metal element that is not desired in the semiconductor industry, the condition is that etching corrosion resistance is extremely excellent.

When a metal oxide is mixed with quartz glass powder as one of the doping methods, it is melted in a heat treatment furnace or by the Bernoulli method. At this time, the melting point of the doped metal oxide is 2500 ° C. or higher. In such a case, it is difficult to sufficiently melt the metal oxide powder by the current production method, and the powder remains as a powder or remains in a crystal and is visually observed as a fine white foreign substance. Is preferably doped with a metal oxide having a melting point of less than 2500 ° C. It is naturally effective to co-dope not only a single metal element but also a plurality of metal elements.

The concentration of the metal element is 0.1 to 20% by weight.
Is preferable, and 1.0 to 15% by weight is more preferable. As a result of an experiment in which doping was performed while changing the metal element concentration, no improvement in etching resistance was confirmed when the metal element concentration was less than 0.1 wt%. On the other hand, if the content exceeds 20 wt%, the doping amount is too large, and it is difficult to suppress the generation of bubbles and foreign substances.
Any technique was difficult.

A quartz glass jig excellent in plasma corrosion resistance of the present invention is made of the quartz glass of the present invention described above, has a thickness from a surface to a predetermined depth, and contains 0.1 to 20% by weight of the above metal element. A metal element-containing layer to be formed. The thickness of the metal element-containing layer is preferably at least 5 mm.

In the case of a normal quartz glass jig, the depth at which it comes into contact with the plasma gas and corrodes is approximately 1 to 2 mm under current general use conditions, and at most about 5 mm. Since the initial shape and characteristics can be maintained, the above-described metal element is added in an amount of 0.1 to 20 wt%.
Improving the etching resistance by setting the thickness of the metal element-containing layer to at least 5 mm is a preferable condition when the quartz glass having excellent plasma corrosion resistance of the present invention is used as a quartz glass jig.

The metal element contained in the metal element-containing layer may be doped in a quartz glass jig, or may be coated on the surface of the quartz glass jig by a surface coat. Good thing.

The first embodiment of the method of the present invention for producing quartz glass having excellent plasma corrosion resistance is a Bernoulli method, which is a method for producing an ingot using an oxyhydrogen flame, which comprises producing quartz glass ingots having excellent plasma corrosion resistance from quartz powder. When a metal element powder or a compound powder thereof is mixed with quartz powder and melted and dropped by heating to form a quartz glass ingot, the quartz glass ingot surface temperature is set to 1800 ° C.
The heating is preferably performed at 3000 ° C. or less.

The second aspect of the method of the present invention for producing quartz glass having excellent plasma corrosion resistance is a method for producing a quartz glass ingot having excellent plasma corrosion resistance from quartz powder by the Bernoulli method, wherein the quartz powder is heated, melted and dropped. At the same time as producing a quartz glass ingot, a solution prepared by dissolving a metal element or a compound thereof in pure water, an acidic solution, a basic solution or an organic solvent is continuously dropped on the growth surface of the quartz glass ingot. Features.

When a metal element or a compound thereof is doped into quartz glass with a powder, the metal element powder or the compound powder is decomposed into the atomic or molecular level in the SiO ₂ powder, uniformly diffused and mixed. As described above, it is necessary to perform heating and melting while giving sufficient thermal energy.

For this reason, it is preferable that the form of the metal element when doped is a gas or a liquid. In the case of mixing with a powder, the particle size of the powder is preferably as small as possible. In particular, since the metal element exists as an oxide in the SiO ₂ network and is easily concentrated, it is preferable that the melting point of the oxide is as low as possible. Good.

Usually, the method of mixing quartz powder and doped metal element powder and melting them in a heating furnace, which is the most common method of production, has a limit in a possible high temperature range. Have difficulty.

When the Bernoulli method is employed as the production method, the thermal energy density applied to the powder can be supplied uniformly and at a high level, so that it is possible to form a quartz glass body with less bubbles and foreign matters. If the melting point of the metal oxide used is up to about 2500 ° C., the metal oxide can be melt-diffused by adjusting the surface temperature of the formed ingot to a temperature close to that temperature or higher.

As the powder, a metal powder, an oxide, a nitric acid compound, a chloride and other compounds are mixed with quartz powder. Instead of powder, a solution in which the metal element is uniformly dissolved at the atomic or molecular level is dropped in liquid form on the growth surface of the ingot being formed, or is vaporized or placed on a carrier gas to form the ingot. A doping method such as spraying on a growth surface is very effective. Examples of the solution include a solution in which metal powder is dissolved in an acidic or alkaline solution, a solution in which a nitric acid compound is dissolved in pure water, a solution in which a chlorine compound is dissolved in ethanol or the like, a solution of an organometallic compound or a solid thereof in an organic solvent. A solution prepared by dissolving in water is also used.

The third embodiment of the method for producing quartz glass having excellent plasma corrosion resistance according to the present invention is a porous glass prepared in advance.
The iO ₂ bodies, the density of metal elements (0.1 to 10 mol)
/22.4 liters, and heat-treated.

The third embodiment of the method of the present invention is generally defined as a CVD method as a method of diffusing a gaseous tough substance into a porous material. In the third aspect of the method of the present invention, the gas density of the metal element is (0.
The porous SiO ₂ body is allowed to stand still in a gas having a concentration range of 1 to 10 mol) /22.4 liters and subjected to a heat treatment. After the treatment is continued until the gas is sufficiently diffused in the porous body, the temperature is lowered, so that the oxide remains in the porous body without being locally concentrated, though it is in an oxide state. Since increasing the gas density increases the residual oxide concentration, it is more effective to set the heating temperature as low as possible and the pressure as high as possible. The heating temperature is equal to or higher than the boiling point, sublimation point and decomposition point of the metal element or its compound.
A range from 10 to 10 atmospheres is preferred.

According to a fourth aspect of the method of the present invention for producing quartz glass having excellent plasma corrosion resistance, the particle size distribution of the whole glass is 0.1 mm.
In the range of from 0.1 to 1000 μm, of which 0.1.
The weight ratio of the particle group in the range of 01 to 5 µm is 1 to 50 wt%
A silica glass powder and a metal element or a compound thereof that can be dissolved in pure water, an acidic solution, a basic solution, or an organic solvent are mixed and dissolved in pure water, an acidic solution, a basic solution, or an organic solvent, and the slurry is obtained. After drying and solidifying the slurry, the slurry is heated and melted under vacuum. Such a manufacturing method is generally defined as a slip casting method.

In a method in which quartz powder is dissolved in pure water, an aqueous solution of a metal element is mixed therewith to form a slurry, and the slurry is dried and heated under vacuum to form a transparent solid. It is necessary to mix particles having a particle size of 5 μm or less in the range of 1 to 50 wt%. This particle group may be finely crushed quartz powder or fumed silica prepared by flame hydrolysis of silicon tetrachloride.

Examples of the aqueous solution of the metal element include a solution in which metal powder is dissolved in an acidic or alkaline solution, a solution in which a nitrate compound is dissolved in pure water, a solution in which a chlorine compound is dissolved in an organic solvent such as ethanol, and an organic metal solution. A compound or a solution prepared by dissolving it in an organic solvent is used. In particular, when a solution in which a nitric acid compound is dissolved in pure water is used,
The resulting quartz glass body is suitable with few bubbles.

The method for producing a quartz glass jig excellent in plasma corrosion resistance according to the present invention comprises the steps of: dissolving a metal element or a compound thereof soluble in pure water, an acidic solution, a basic solution or an organic solvent; It is characterized in that a solution or a solution prepared by mixing and dissolving in an organic solvent is applied to the surface of a quartz glass jig prepared in advance, and then the surface is heated and melted.

In particular, when focusing on increasing the metal element concentration on the surface of the quartz glass jig,
It is effective to apply a metal element solution and then heat and melt it. The metal element solution is prepared by dissolving a metal element powder in an acidic or alkaline solution, dissolving a nitrate compound of a metal element in pure water, or dissolving a chlorine compound of a metal element in an organic solvent such as ethanol, An organometallic compound containing a metal element or a solution prepared by dissolving the same in an organic solvent may be applied to the surface of a quartz glass jig, painted with a brush, or sprayed with a spray. As the metal element solution, an organic metal compound containing a metal element or a solution prepared by dissolving the same in an organic solvent is particularly suitable.

After that, the surface is melted by a method such as flame melting, electric heating, arc melting or the like, and the metal element is baked.
In this case, if the quartz glass jig is already doped with a metal element, the concentration of the metal element as a whole is preferably high. In addition, it has good compatibility with the formed surface containing a metal element at a high concentration, and it is difficult for cracks or the like to be formed when the surface is cooled after the treatment.

As the quartz glass jig prepared in advance, a conventionally known quartz glass jig can be used, but a quartz glass jig manufactured by the above-described method for manufacturing quartz glass having excellent plasma corrosion resistance of the present invention is used. Is preferably used.

As a means for measuring the local concentration of the metal element, a surface distribution can be measured by EPMA (Electron Probe MicroAnalysis), and since the portion shows crystallinity, X
It can also be determined by a line diffraction or a deflection microscope.

[0036]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, it is needless to say that these examples are shown by way of example and are not to be construed as limiting. .

Example 1 1900 g of quartz particles and Al ₂
100 g of O ₃ powder is mixed and 50 g / mi in an oxyhydrogen flame
It melted and dropped on a target ingot rotating at 1 rpm at a speed of n to produce a quartz glass ingot of 200 mmφ × 50 mm. The gas conditions used are H ₂ 200 l / min and O ₂ 100 l / mi.
n. Target ingot is 300mm x 30
It is set in a volume of 0 mm x 200 mmH. When the gas amount is less than this, bubbles and foreign substances are generated, and when the gas amount is more than this, the shape of the ingot collapses. The temperature of the ingot growth surface was 2200 ° C.

When the aluminum concentration of the prepared ingot was measured by X-ray fluorescence analysis, the concentration from the surface to 0.1 mm was 3.0 wt%, and the concentration at the depth of 5.0 mm from the surface was 2.0 wt%. Was. Excluding the surface, the average concentration over the entire length of the formed ingot is approximately 2.0 wt%
Met. Since the sublimation of quartz proceeds at the outermost surface portion, the concentration is considered to be high.

The content of bubbles and foreign substances was measured and the presence or absence of foreign substances was examined by X-ray diffraction for the prepared ingot. The results are shown in Table 1. No foreign matter was present, and the content of bubbles and foreign matter was 39 mm ² .

Further, as will be described later, the amount of generated particles and the etching rate were measured, and the results are shown in Table 1. The amount of particles generated was small and the etching rate was sufficiently low, confirming that the plasma corrosion resistance was excellent.

Example 2 Quartz particles were placed in an oxyhydrogen flame for 5 minutes.
At a speed of 0 g / min, the solution was melted and dropped on a target ingot rotating at 1 rpm.
While dropping at a rate of cc / min,
A 50 mm quartz glass ingot was made. The gas conditions used are as follows: H ₂ is 150 liter / min, O ₂ is 75
Liter / min. Target ingot is 3
It is set in a volume of 00 mm x 300 mm x 200 mmH.

When the aluminum concentration of the produced quartz glass ingot was measured by X-ray fluorescence analysis, the outermost surface portion (from the surface to 0.1 mm) was 3.0 wt% and 5 mm
In the part at the depth, it was 1.0 wt%. Since the sublimation of quartz proceeds at the outermost surface portion, the concentration is considered to be high.
The average concentration of aluminum over the entire length of the formed ingot was approximately 1.5 wt%. Example 1
The same items as those described above were measured, and the results are shown in Table 1. As is clear from the results in Table 1, it was confirmed that the plasma corrosion resistance was excellent.

Example 3 A quartz glass ingot was produced in the same manner as in Example 2 except that zirconium nitrate was used instead of aluminum nitrate as a doping material.
The zirconium concentration of the produced quartz glass ingot was measured and at the same time, the same items as in Example 1 were measured. The results are shown in Table 1. It was confirmed that the plasma corrosion resistance was excellent.

Example 4 A quartz glass ingot was prepared in the same manner as in Example 2 except that yttrium nitrate was used instead of aluminum nitrate as a doping material. The yttrium concentration of the produced quartz glass ingot was measured, and at the same time, the same items as in Example 1 were measured. The results are shown in Table 1. As is clear from the results in Table 1, it was confirmed that the plasma corrosion resistance was excellent.

[0045]

[Table 1]

Example 5 Example 2 was repeated except that samarium nitrate was used instead of aluminum nitrate as the doping material.
A quartz glass ingot was prepared in the same manner as described above. While measuring the samarium concentration of the produced quartz glass ingot, the same items as in Example 1 were also measured,
The results are shown in Table 2. As is clear from the results in Table 2, it was confirmed that the plasma corrosion resistance was excellent.

Example 6 A quartz glass ingot was prepared in the same manner as in Example 2, except that a 30 wt% solution of aluminum nitrate was dissolved in ethanol instead of a 30 wt% aqueous solution of aluminum nitrate as a doping material. The aluminum concentration of the produced quartz glass ingot was measured, and the same items as in Example 1 were measured. The results are shown in Table 2. As is clear from the results in Table 2, it was confirmed that the plasma corrosion resistance was excellent.

Example 7 A quartz glass ingot was prepared in the same manner as in Example 2 except that a 30 wt% aqueous solution of aluminum nitrate was used instead of a 30 wt% aqueous solution of aluminum nitrate as a doping material. The aluminum concentration of the produced quartz glass ingot was measured, and at the same time, the same items as in Example 1 were measured. The results are shown in Table 2. As is clear from the results in Table 2, it was confirmed that the plasma corrosion resistance was excellent.

Example 8 Instead of a 30 wt% aqueous solution of aluminum nitrate as a doping material, Al was added to propanol.
A quartz glass ingot was prepared in the same manner as in Example 2 except that 30 wt% of isopropoxide was used. The aluminum concentration of the produced quartz glass ingot was measured, and at the same time, the same items as in Example 1 were measured. The results are shown in Table 2. As is clear from the results in Table 2, it was confirmed that the plasma corrosion resistance was excellent.

[0050]

[Table 2]

Example 9 A quartz glass ingot was prepared in the same manner as in Example 2 except that a 30 wt% aqueous solution of aluminum nitrate was used as a doping material instead of aluminum silicate in which 30 wt% of aluminum isopropoxide was dissolved. It was created. The aluminum concentration of the produced quartz glass ingot was measured, and at the same time, the same items as in Example 1 were measured. The results are shown in Table 3. As is clear from the results in Table 3, it was confirmed that the plasma corrosion resistance was excellent.

(Embodiment 10) Fifty samples prepared by the soot method
A silica glass matrix having a size of 0 mmφ × 1000 mm was mixed with 500 g of aluminum chloride granules in 600 mmφ × 12 mm.
After setting in a 00 mm quartz glass container and replacing with N ₂ atmosphere, the gas introduction line was closed and heating was started.
The temperature was raised to 400 ° C, and the total amount of aluminum chloride was sublimated to 10
After the atmosphere was 0% concentration, it was kept at 10 HR under the atmospheric pressure, the heating was stopped, the temperature was lowered to room temperature, and then taken out.
The soot taken out was heated to 1800 ° C. in a vacuum furnace to form a transparent glass.

From the surface of the formed quartz glass,
3 wt% of aluminum was detected, but at a depth of 5 mm, it was 2.0 wt%. The average concentration of aluminum in the formed quartz glass was approximately 1.1 wt%. It is presumed that aluminum was detected at a high concentration on the surface because alumina remained while SiO ₂ sublimated during the vitrification.

The boiling point of aluminum chloride is 180 ° C.
When the processing temperature is 150 ° C. or less, the sublimation vapor pressure is 70 mmH
g or less, and the concentration of aluminum chloride gas in the atmosphere is 0.0
8 mol / 22.4 liters, the aluminum concentration in the glass was about 0.01 wt%. If the temperature exceeds 633 ° C., the aluminum concentration in the atmosphere becomes 0.5 mol /
It became 22.4 liters, and the aluminum concentration in the obtained glass was reduced by half.

Further, the same items as in Example 1 were measured, and the results are shown in Table 3. As is clear from the results in Table 3, it was confirmed that the plasma corrosion resistance was excellent.

(Embodiment 11) Fifty samples prepared by the soot method
A silica glass matrix of 0 mmφ × 1000 mm, together with 500 g of aluminum chloride granules, was set in a closed high-pressure vessel, and after substituting with a N ₂ atmosphere, closing the gas introduction line, starting heating, and raising the temperature to 250 ° C. The total amount of aluminum chloride is sublimated to a high-pressure atmosphere of 10 kg / cm ² , that is, 9 mol / 22.4 liters, then maintained at 10 HR, stopped heating, cooled down to room temperature, and taken out.

The soot taken out is placed in a vacuum furnace for 1
It was heated to 800 ° C. to make it transparent glass. Although 6 wt% of aluminum was detected from the surface portion, it was 3.0 wt% at a portion having a depth of 5 mm. The average concentration of aluminum in the formed transparent glass was approximately 4.0 wt%. The aluminum chloride gas concentration in the atmosphere, the aluminum concentration in the glass, and the aluminum concentration in the obtained glass were the same as in Example 10.

Further, the same items as in Example 1 were measured, and the results are shown in Table 3. As is clear from the results in Table 3, it was confirmed that the plasma corrosion resistance was excellent.

(Example 12) Quartz was prepared in the same manner as in Example 10 except that zirconium chloride granules were used as doping materials instead of aluminum chloride granules, and the temperature was raised to 500 ° C to sublimate the entire amount of zirconium chloride. A glass ingot was created. The zirconium concentration of the quartz glass ingot thus prepared was measured, and at the same time, the same items as in Example 1 were measured. The results are shown in Table 3. As is clear from the results in Table 3, it was confirmed that the plasma corrosion resistance was excellent.

[0060]

[Table 3]

(Example 13) Particle size of 500 μm to 100
750 g of quartz powder of 200 μm, 200 g of pyrogenic silica particles having a particle size of 0.01 μm to 4 μm, and 700 g of aluminum nitrate.
g and pure water 1500 g to prepare a slurry. This slurry was dried in the air at 40 ° C. for 8 days to be solid, and then subjected to a heat treatment at 1800 ° C. and 1 HR in a vacuum atmosphere to produce a transparent glass of 100 mmφ × 50 mmH. The aluminum concentration was 2.0 wt% in the entire bulk.

The same items as in Example 1 were measured, and the results are shown in Table 4. As is clear from the results in Table 4, it was confirmed that the plasma corrosion resistance was excellent.

(Example 14) A quartz glass ingot was prepared in the same manner as in Example 13 except that zirconium nitrate was used instead of aluminum nitrate as a doping material. The zirconium concentration of the produced quartz glass ingot was measured and at the same time, the same items as in Example 1 were measured. The results are shown in Table 4. As is clear from the results in Table 4, it was confirmed that the plasma corrosion resistance was excellent.

Example 15 A quartz glass ingot was produced in the same manner as in Example 13 except that yttrium nitrate was used instead of aluminum nitrate as a doping material.
The yttrium concentration of the produced quartz glass ingot was measured, and at the same time, the same items as in Example 1 were measured. The results are shown in Table 4. As is clear from the results in Table 4, it was confirmed that the plasma corrosion resistance was excellent.

Example 16 A quartz glass ingot was produced in the same manner as in Example 13 except that samarium nitrate was used instead of aluminum nitrate as a doping material. The samarium concentration of the produced quartz glass ingot was measured, and at the same time, the same items as in Example 1 were measured. The results are shown in Table 4. As is clear from the results in Table 4, it was confirmed that the plasma corrosion resistance was excellent.

[0066]

[Table 4]

Example 17 A quartz glass ingot was prepared in the same manner as in Example 13 except that 700 g of aluminum chloride and 1500 g of ethanol were used instead of 700 g of aluminum nitrate and 1500 g of pure water as a doping material. The aluminum concentration of the produced quartz glass ingot was measured, and at the same time, the same items as in Example 1 were measured. The results are shown in Table 5. As is clear from the results in Table 5, it was confirmed that the plasma corrosion resistance was excellent.

Example 18 A quartz glass ingot was prepared in the same manner as in Example 13, except that 700 g of aluminum nitrate and 1500 g of pure water were used as doping materials instead of aluminum, which was dissolved at 5 wt% in hydrochloric acid.
The aluminum concentration of the produced quartz glass ingot was measured, and at the same time, the same items as in Example 1 were measured. The results are shown in Table 5. As is clear from the results in Table 5, it was confirmed that the plasma corrosion resistance was excellent.

Example 19 A quartz glass ingot was prepared in the same manner as in Example 13 except that a material obtained by dissolving 30% by weight of Al.isopropoxide in propanol was used instead of 700 g of aluminum nitrate and 1500 g of pure water as a doping material. It was created. The aluminum concentration of the produced quartz glass ingot was measured, and at the same time, the same items as in Example 1 were measured. The results are shown in Table 5. Table 5
As is clear from the results, it was confirmed that the plasma corrosion resistance was excellent.

(Example 20) Quartz glass was prepared in the same manner as in Example 13 except that Al-isopropoxide was dissolved at 30 wt% in ethyl silicate instead of 700 g of aluminum nitrate and 1500 g of pure water as a doping material. Ingot created. The aluminum concentration of the produced quartz glass ingot was measured, and at the same time, the same items as in Example 1 were measured. The results are shown in Table 5. As is clear from the results in Table 5, it was confirmed that the plasma corrosion resistance was excellent.

[0071]

[Table 5]

Example 21 200 mmφ × 20 mm
A solution obtained by dissolving aluminum isopropoxide in propanol is dropped on the surface of the (thickness) quartz glass jig and hydrolyzed with moisture in the air to form an alumina film. The film-formed surface of this quartz glass plate was fire-polished and baked with an oxyhydrogen flame to form a smooth transparent molten surface. 0.1m from surface
The average aluminum concentration up to 1 mm is 15 wt%, but the average aluminum concentration up to 1 mm is 0.5 wt%.
%Met. The average concentration of aluminum in the formed quartz glass jig was approximately 2.1 wt%.

Further, the same items as in Example 1 were measured, and the results are shown in Table 6. As is clear from the results in Table 6, it was confirmed that the plasma corrosion resistance was excellent.

(Example 22) A quartz glass ingot was prepared in the same manner as in Example 21 except that a solution in which aluminum isopropoxide was dissolved in ethyl silicate was used instead of a solution in which aluminum isopropoxide was dissolved in propanol. . The aluminum concentration of the produced quartz glass ingot was measured, and at the same time, the same items as in Example 1 were measured. The results are shown in Table 6. As is clear from the results in Table 6, it was confirmed that the plasma corrosion resistance was excellent.

Example 23 A quartz glass ingot was prepared in the same manner as in Example 21 except that a solution in which zirconium isopropoxide was dissolved in propanol was used instead of a solution in which aluminum isopropoxide was dissolved in propanol. The zirconium concentration of the produced quartz glass ingot was measured and at the same time, the same items as in Example 1 were measured. The results are shown in Table 6. As is clear from the results in Table 6, it was confirmed that the plasma corrosion resistance was excellent.

Example 24 A quartz glass ingot was prepared in the same manner as in Example 21 except that a solution in which titanium isopropoxide was dissolved in propanol was used instead of a solution in which aluminum isopropoxide was dissolved in propanol. The titanium concentration of the produced quartz glass ingot was measured, and at the same time, the same items as in Example 1 were measured. The results are shown in Table 6. As is clear from the results in Table 6, it was confirmed that the plasma corrosion resistance was excellent.

[0077]

[Table 6]

Example 25 The same procedure as in Example 21 was carried out except that a solution prepared by dissolving aluminum nitrate in pure water was used instead of a solution obtained by dissolving aluminum isopropoxide in propanol, and then this surface was fire-polished. To produce a quartz glass ingot. The aluminum concentration of the produced quartz glass ingot was measured, and at the same time, the same items as in Example 1 were measured. The results are shown in Table 7. As is clear from the results in Table 7, it was confirmed that the plasma corrosion resistance was excellent.

Example 26 A quartz glass ingot was prepared in the same manner as in Example 25 except that a solution prepared by dissolving 30 wt% of aluminum chloride in ethanol was used instead of a solution of aluminum isopropoxide in propanol. . The aluminum concentration of the produced quartz glass ingot was measured, and at the same time, the same items as in Example 1 were measured. The results are shown in Table 7. As is clear from the results in Table 7, it was confirmed that the plasma corrosion resistance was excellent.

Example 27 A quartz glass ingot was prepared in the same manner as in Example 25, except that a solution in which aluminum was dissolved in hydrochloric acid at 5 wt% was used instead of the solution in which aluminum isopropoxide was dissolved in propanol. The aluminum concentration of the produced quartz glass ingot was measured, and at the same time, the same items as in Example 1 were measured. The results are shown in Table 7. As is clear from the results in Table 7, it was confirmed that the plasma corrosion resistance was excellent.

(Embodiment 28) The quartz glass body formed in the embodiment 1 is processed to have a size of 200 mmφ × 25 mm (thickness).
Was made. Example 2 on the upper surface of this jig
A high concentration aluminum distribution layer was formed by the method of Example 1. The average aluminum concentration from the surface to 0.1 mm is
Although it was 15 wt%, the average aluminum concentration up to 1 mm was 4.0 wt%. The average concentration of aluminum in the prepared quartz glass jig was approximately 4.0% by weight. The same items as in Example 1 were measured, and the results are shown in Table 7. As is clear from the results in Table 7,
It was confirmed that the plasma corrosion resistance was excellent.

[0082]

[Table 7]

Comparative Example 1 Particle Size: 500 μm to 100 μm
Is filled in a carbon mold and subjected to a heat treatment at 1800 ° C. and 1 HR in a vacuum atmosphere.
A transparent glass of 100 mmφ × 50 mmH was prepared. The same items as in Example 1 were measured, and the results are shown in Table 8. As is clear from the results in Table 8, the etching rate was extremely high and the plasma corrosion resistance was poor.

(Comparative Example 2) Particle size 500 μm to 100 μm
900 g of quartz powder and 100 g of alumina were mixed, filled in a carbon mold, and heated at 1800 ° C. in a vacuum atmosphere.
HR heat treatment was performed to produce a transparent glass of 100 mmφ × 50 mmH. Aluminum concentration is 2.0wt
%Met. Bubbles and foreign matter were confirmed in the glass body.

The same items as in Example 1 were measured, and the results are shown in Table 8. As is clear from the results in Table 8, the content of bubbles and foreign matters was large, the amount of generated particles was large, and the silicon wafer was unsuitable as a jig for a silicon wafer. Further, the etching rate was high and the plasma corrosion resistance was poor.

Comparative Example 3 690 g of quartz particles and Al_TwoO_Three
310 g of powder were mixed and 50 g / min
On the target ingot rotating at 1 rpm at speed
Melt and drop, 200mmφ × 500 liter ingot
Created The gas condition used is H _TwoIs 200 l
Tol / min, O_TwoIs 100 liters / min
Was. Target ingot is 300mm x 300mm
Set in a volume of × 500 mmH. Bubbles and foreign matter frequently
As a result, the gas flow rate was increased by a factor of two each, but did not improve.
With more gas, the shape of the ingot collapsed.

The aluminum concentration of the formed ingot was measured by X-ray fluorescence analysis.
wt%, and 13.0 wt% at 5 mm depth.
Met. Since the sublimation of quartz proceeds at the outermost surface portion, the concentration is considered to be high.

The same items as in Example 1 were measured, and the results are shown in Table 8. As is clear from the results in Table 8, although the etching rate was low, the content of bubbles and foreign matters was large, the amount of particles generated was large, and it was found to be unsuitable as a jig for silicon wafer.

[0089]

[Table 8]

The contents of bubbles and foreign substances in the above Examples and Comparative Examples were measured as follows. Cut out a 50 mm x 50 mm x 1 mm (thickness) sample from the target quartz glass body, polish both sides to a mirror surface, allow white light to pass through from the bottom of this sample, project bubbles and foreign matter shadows, and analyze the image. using a device to measure the number of the above foam and foreign matters diameter 0.02 mm, from the results, calculated bubbles and foreign matter sectional area of the cut samples throughout the (projected area), from which, per 100 cm ³ cross The area (projected area) was converted and calculated.

The etching rate was measured as follows. A sample was cut out from the formed transparent quartz glass, processed into a size of 30 mmφ × 3 mm (thickness), and fire-polished the surface state, and 50 sccm CF ₄ + O
₂ (20%) plasma gas at 30 mTorr, 1k
w, an etching test of 10 HR was performed. The thickness change was calculated from the weight change before and after the test, and the etching rate was calculated by dividing by the processing time.

Regarding the amount of generated particles,
After the etching, an Si wafer having the same area was placed on the plasma irradiation surface of the sample, and the unevenness of the contact surface of the wafer was detected by laser scattering, and the number of particles of 0.3 μm or more was measured by a particle counter.

In each of the examples and comparative examples, when the amount of generated particles is 50 or less, the usable portion of the Si wafer is 90% or more.
Below, the yield was significantly reduced. When the etching rate is 100 nm / min or more, the etching thickness becomes 0.6 mm with a use time of about 100 HR and cannot be used as a member. However, when the etching rate is 50 nm / min or less, the usable time is doubled. The effect was confirmed, and especially when it was 20 nm / min or less, the effect became extremely economical.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akira Fujinoki 88, Kawakubo, Kanaya, Tamura-cho, Koriyama-shi, Fukushima Prefecture Inside the Quartz Research Laboratory of Shin-Etsu Quartz Co., Ltd. No. 2 Shin-Etsu Quartz Co., Ltd. (72) Inventor Tomoyuki Shirai 1-22-2 Nishi Shinjuku, Shinjuku-ku, Tokyo Shin-Etsu Quartz Co., Ltd. F-term (reference) 4G014 AH02 4G062 BB02 CC04 DB02 DB03 DB04 FB02 FB03 FB04 FC02 FC03 FC04 FJ02 FJ03 FJ04 KK02 MM17 NN34 5F004 BB29 DA01 DA26 5F045 AA08 EB03

Claims (14)

[Claims] 1. A quartz glass containing a metal element and having increased plasma corrosion resistance, wherein the content of bubbles and foreign matter in the quartz glass is less than 100 mm ^{2 in} a projected area per 100 cm ^3. Quartz glass with excellent corrosion resistance. 2. The quartz glass excellent in plasma corrosion resistance according to claim 1, wherein the boiling point of the fluoride of the metal element is higher than the boiling point of the fluoride of Si. 3. The concentration of the metal element is 0.1 to 20 wt.
%. 4. The quartz glass excellent in plasma corrosion resistance according to claim 1 or 2. 4. It is made of the quartz glass according to claim 1, has a thickness from a surface to a predetermined depth, and contains 0.1 to 20 watts of said metal element.
A quartz glass jig excellent in plasma corrosion resistance, wherein a metal element-containing layer containing t% is formed. 5. The quartz glass jig excellent in plasma corrosion resistance according to claim 4, wherein the thickness of the metal element-containing layer is at least 5 mm. 6. A method for producing a quartz glass ingot having excellent plasma corrosion resistance from quartz powder by a Bernoulli method,
When the metal element powder or its compound powder is mixed with quartz powder and melted by heating and dropped to form a quartz glass ingot, the surface temperature of the quartz glass ingot is heated to 1800 ° C. or more, which is excellent in plasma corrosion resistance. Method of manufacturing quartz glass. 7. A method for producing a quartz glass ingot excellent in plasma corrosion resistance from quartz powder by a Bernoulli method,
The quartz powder is heated and melted and dropped to form a quartz glass ingot.At the same time, a solution prepared by dissolving a metal element or its compound in pure water, an acidic solution, a basic solution or an organic solvent is continuously applied to the growth surface of the quartz glass ingot. A method for producing quartz glass having excellent plasma corrosion resistance, characterized in that it is dripped selectively. 8. A porous SiO ₂ body prepared in advance, wherein the density of the metal element is (0.1 to 10 mol) /22.4.
A method for producing quartz glass having excellent plasma corrosion resistance, wherein the quartz glass is left standing in an atmosphere in a range of 1 liter and heated. 9. The method according to claim 8, wherein the heating temperature is equal to or higher than the boiling point, the sublimation point, and the decomposition point of the metal element or the compound thereof, and the processing pressure is in a range of 1 to 10 atm. Production method. 10. The total particle size distribution is from 0.01 to 100.
0 μm, of which 0.01 to 5 μm
A quartz glass powder in which the weight ratio of the particle groups in the range of 1 to 50 wt% and a metal element or a compound thereof soluble in pure water, an acidic solution, a basic solution or an organic solvent is mixed with pure water, an acidic solution, A method for producing quartz glass having excellent plasma corrosion resistance, comprising mixing and dissolving in a basic solution or an organic solvent to prepare a slurry, drying and solidifying the slurry, and then heating and melting the slurry under vacuum. 11. The metal compound is a nitric acid compound,
The method for producing quartz glass excellent in plasma corrosion resistance according to claim 10, wherein the solvent is pure water. 12. A metal element or a compound thereof which can be dissolved in pure water, an acidic solution, a basic solution or an organic solvent, is added to pure water,
A solution prepared by mixing and dissolving in an acidic solution, a basic solution or an organic solvent, is applied to the surface of a quartz glass jig prepared in advance, and then the surface is heated and melted. Excellent quartz glass jig manufacturing method. 13. The method according to claim 12, wherein the solution containing the metal element is an organic metal compound solution containing the metal element or a solution prepared by dissolving the same in an organic solvent. 14. A quartz glass jig prepared in advance is manufactured by the manufacturing method according to any one of claims 6 to 11.
The manufacturing method as described.