KR101229946B1 - Fabrication method of catalyst based on the nano-silica to decompose PFC gaseous from semiconductor process, and Catalyst based on the nano-silicate to decompose the PFC manufactured by the same - Google Patents

Abstract

The present invention provides a method for preparing a catalyst for the gas-decomposition treatment of a semiconductor process perfluorinated compound having nano silica as a support capable of improving the decomposition performance of a hardly decomposable perfluorinated compound (PFC) gas generated in a semiconductor process. The present invention relates to a catalyst for gas-decomposition treatment of a semiconductor process using nano silica as a support, wherein tetraethyl orthosilicate (TEOS), ammonia water and secondary distilled water are added to ethanol for 6 to 8 hours at 20 to 30 ° C. Stirring to prepare a nano silica solution in a sol state (step 1); Sol nano-silica surface treatment step (step 2) in which Al (OH) ₃ is added to the sol nano-silica solution to precipitate sol nano-silica, and the precipitated sol nano-silica is filtered and washed; Second distilled water was added to the washed sol nano-silica and stirred at 200-400 rpm for 1 hour at 60-80 ° C., Al (OH) ₃ was added as a first catalyst and reacted for 1 hour. 2 was added sulfuric acid (H ₂ SO ₄ ) as a catalyst, a gallium (Ga) oxide as a third catalyst and stirred for 1 hour, the temperature was raised to 100 ℃ to stand for 24 hours to evaporate water dried Catalyst attachment step (step 3) to obtain a solid content; And preparing a nano oxidation catalyst by calcining the dried solids by heat treatment at 550-800 ° C. for 5-12 hours while injecting air in a kiln (step 4); If prepared, the nano-silica provides a spherical surface and physical effects of the PFC gas decomposition efficiency can be further improved due to the physical effect of the nano-silica, by directly supporting and synthesizing three types of catalysts in the sol nano-silica The effect of combining the catalysts chemically in the pores has the advantage of further increasing the waste gas decomposition efficiency.

Description

A method for producing a catalyst for gas-decomposition treatment of a semiconductor process using nano silica as a support, and a catalyst for gas-decomposition treatment of a perfluoro compound gas produced using a nano-silica as a support. silica to decompose PFC gaseous from semiconductor process, and Catalyst based on the nano-silicate to decompose the PFC manufactured by the same}

The present invention relates to a method for preparing a catalyst for gas-decomposition treatment of a semiconductor process using nano silica as a support, and a catalyst for treating a gas-decomposition treatment for a semiconductor process using a nano-silica prepared as a support. Is a method for preparing a catalyst for the decomposition of perfluorinated compound gas in a semiconductor process using nano-silica as a support for improving the decomposition performance of a hardly decomposable perfluorinated compound (PFC) gas generated in a semiconductor process, and nano-silica prepared thereby It relates to a catalyst for semiconductor process perfluorinated compound gas decomposition treatment having a as a support.

In general, a perfluoro compound (PFC) is a gas widely used as an etchant in a semiconductor etching process and a chemical cleaner in a chemical vapor deposition process.

However, since the PFC used in the semiconductor process is not consumed entirely during the process, unreacted gas is often left, and in addition, a gas generated by the secondary may be generated, and even the source gas is discharged from the vacuum pump as it is. In some cases.

As the PFC for this purpose, CF ₄ , CHF ₄ , NF ₄ , SF ₆ and the like can be used, the PFC has a global warming potential (thousands of tens of thousands of times higher than carbon dioxide).

Therefore, the discharge of PFCs into the atmosphere is subject to regulation to protect the environment, and the regulation is expected to be strengthened in the future.

In order to treat PFC generated in a semiconductor process, various removal methods such as direct combustion, plasma decomposition, recovery, and catalytic decomposition are known.

The direct combustion method is a method of directly burning a waste gas containing PFC at a high temperature of 1,400 ° C. or more using a combustible gas, and is one of the simplest treatment methods, but has a high reaction rate and causes various additional problems. The nitrogen and oxygen contained in the PFC react with each other to generate a large amount of harmful nitrogen oxides.

The plasma decomposition method is a technique for decomposing and removing waste gas containing PFC through a plasma region, and is effective for PFC decomposition, but since it uses plasma in a high energy state, secondary reactions of radicals generated by indiscriminate decomposition of PFC are performed. As a result, various kinds of by-products are generated.

The recovery method is a method of separating and recovering the PFC component contained in the waste gas by using a pressure swing adsoption (PSA) or a membrane (membrane) and the like, which is preferable in terms of recycling of PFC, but as in the semiconductor process. It is a low economic method when treating irregularly discharged PFC.

The catalytic decomposition method has been studied as an alternative to the direct combustion method and the plasma decomposition method because the catalyst and water vapor can cause PFC decomposition to occur at a low temperature of 500 to 800 ° C., thereby greatly reducing the generation of nitrogen oxides and device corrosion.

Korean Patent No. 10-0461758 (December 14, 2004) discloses a catalyst capable of decomposing and removing a perfluorinated compound by supporting a phosphorus component on the surface of an aluminum oxide. The catalyst has the advantage of excellent catalytic activity and durability, but has a disadvantage of expensive manufacturing cost because the expensive catalyst is used as a support.

The present inventors have developed a catalyst that can improve the decomposition performance of the perfluorinated compound (PFC) gas while reducing the production cost by reducing the amount of expensive catalyst by supporting and synthesizing three types of catalysts in the sol nano-silica.

KR 10-0461758 (registration number) 2004.12.14.

Disclosure of Invention An object of the present invention is to provide a method for preparing a catalyst for the gas-decomposition treatment of a semiconductor process perfluorinated compound having nano silica as a support capable of improving the decomposition performance of the hardly decomposable perfluorinated compound (PFC) gas generated in the semiconductor process. It is to provide a catalyst for the semiconductor process perfluorinated compound gas decomposition treatment using the prepared nano silica.

In order to achieve the above object, the present invention provides the following means.

In the present invention, tetraethyl orthosilicate (TEOS), ammonia water and secondary distilled water are added to ethanol and stirred at 20 to 30 ° C. for 6 to 8 hours to prepare a sol nano silica solution (step 1). ; Sol nano-silica surface treatment step (step 2) in which Al (OH) ₃ is added to the sol nano-silica solution to precipitate sol nano-silica, and the precipitated sol nano-silica is filtered and washed; Second distilled water was added to the washed sol nano-silica and stirred at 200-400 rpm for 1 hour at 60-80 ° C., Al (OH) ₃ was added as a first catalyst and reacted for 1 hour. 2 was added sulfuric acid (H ₂ SO ₄ ) as a catalyst, a gallium (Ga) oxide as a third catalyst and stirred for 1 hour, the temperature was raised to 100 ℃ to stand for 24 hours to evaporate water dried Catalyst attachment step (step 3) to obtain a solid content; And preparing a nano oxidation catalyst by calcining the dried solids by heat treatment at 550-800 ° C. for 5-12 hours while injecting air in a kiln (step 4); It provides a method for producing a catalyst for the semiconductor process perfluorinated compound gas decomposition treatment having a nano-silica as a support comprising a.

In step 1, 60 to 100 parts by weight of tetraethyl orthosilicate (TEOS), 40 to 60 parts by weight of ammonia and 80 to 100 parts by weight of secondary distilled water are added to 1,000 parts by weight of ethanol.

In step 2, Al (OH) ₃ is characterized in that 1 to 5 parts by weight based on 100 parts by weight of TEOS introduced in step 1.

In the step 3, Al (OH) ₃ is the first catalyst is added 1 to 100 parts by weight based on 100 parts by weight of TEOS introduced in step 1, the sulfuric acid is the second catalyst Al (OH) 1 to 15 parts by weight based on ₃ parts by weight, and the gallium (Ga) oxide as the third catalyst is added to 5 to 40 parts by weight based on 100 parts by weight of Al (OH) ₃ added in step 3. It is done.

In addition, the present invention provides a catalyst for a semiconductor process perfluorinated compound gas decomposition treatment having nano silica as a support, which is produced by the above production method.

Semiconductor process perfluorinated compound gas decomposition treatment using nano silica as a support is an oxidation catalyst for PFC decomposition using spherical nano silica as a support, and the physical effect of the sphere and surface provided by nano silica is provided. Due to this, the PFC gas decomposition efficiency can be further improved, and the three catalysts are directly supported and synthesized in the sol state of the nano-silica, and the effect of the catalysts being mutually chemically combined in the pores of the nanoparticles further increases the waste gas decomposition efficiency. There is this.

The catalyst of the present invention is a physicochemically improved catalyst which can increase the decomposition efficiency while reducing the use of expensive catalysts, compared to the conventional catalysts.

1 to 5 are SEM images of the nano-oxidation catalyst prepared in Examples 1 to 5.
Figure 6 is a schematic diagram showing the experimental equipment for the waste gas decomposition performance analysis.
Figure 7 is a graph of the decomposition performance analysis for SF ₆ gas of the nano-oxidation catalyst prepared in Examples 1 to 5.
8 is a graph of decomposition performance analysis for CF ₄ gas of the nano-oxidation catalyst prepared in Examples 1 to 5.
9 is a graph comparing the decomposition performance of the SF ₆ and CF ₄ gas of the nano-oxidation catalyst prepared in Examples 1 to 5.

Hereinafter, the present invention will be described in detail.

The present invention uses physically spherical nano-silica as a support in order to improve the efficiency of the catalyst for decomposing the perfluoro compound (PFC) gas discharged from the semiconductor process, chemically sol state It is characterized by providing a method for preparing a catalyst to form a structure by combining aluminum ions, gallium oxide and sulfuric acid in the nano-silica.

First, a method for preparing a catalyst for processing a perfluoro compound gas decomposition using a nano silica as a support according to the present invention will be described.

The method for producing a catalyst for the semiconductor process perfluorinated compound gas decomposition treatment using the nano silica of the present invention as a support,

Tetraethyl orthosilicate (TEOS), ammonia water and secondary distilled water were added to ethanol and stirred at 20 to 30 ° C. for 6 to 8 hours to prepare a sol nano silica solution (step 1);

Sol nano-silica surface treatment step (step 2) in which Al (OH) ₃ is added to the sol nano-silica solution to precipitate sol nano-silica, and the precipitated sol nano-silica is filtered and washed;

Second distilled water was added to the washed sol nano-silica and stirred at 200-400 rpm for 1 hour at 60-80 ° C., Al (OH) ₃ was added as a first catalyst and reacted for 1 hour. 2 was added sulfuric acid (H ₂ SO ₄ ) as a catalyst, a gallium (Ga) oxide as a third catalyst and stirred for 1 hour, the temperature was raised to 100 ℃ to stand for 24 hours to evaporate water dried Catalyst attachment step (step 3) to obtain a solid content; And

Preparing the nano-oxidation catalyst by heat-treating the dried solids for 5 to 12 hours at 550 to 800 ° C. while injecting air into the firing furnace (step 4);

.

In step 1, 60 to 100 parts by weight of tetraethyl orthosilicate (TEOS), 40 to 60 parts by weight of ammonia water and 80 to 100 parts by weight of secondary distilled water were added to 1,000 parts by weight of ethanol for 6 to 8 hours at 20 to 30 ° C. Stirring to prepare a nano-silica solution in a sol state.

Instead of TEOS, a material capable of providing silicon such as water glass (sodium silicate), silicon alkoxides (Si (OR) 4), and the like may be used.

In step 1, the spherical nano-silica may combine the hydrodynamic advantages provided by the spherical body and the advantages provided by the nano-sized particles to provide an optimal reaction condition.

The catalyst of the present invention is formed into a spherical shape, the gas passing through it is in uniform contact with the surface of the particles to reduce the waste of the particle constituents, and to uniformly space the filled interparticle space, can induce a uniform chemical reaction throughout the region, The spacing generated at the contact surface between the spherical particles can further enhance the catalytic reaction by the size of several micro units.

In addition, the catalyst of the present invention is composed of nano-sized particles, to provide a surface for the gas decomposition reaction of several tens to hundreds of times larger than the micro-size particles per unit weight.

The catalyst component trapped inside the conventional particles has a problem that can not participate in the reaction, the catalyst of the present invention has the advantage of solving the conventional problem because the particles of the nano-size.

After the secondary distilled water is made of purified primary water using reverse osmosis, the secondary purified water may be prepared through an ion exchange process, ultraviolet sterilization, and photooxidation by an electrical method.

In step 2, in order to precipitate the sol nano silica, Al (OH) ₃ is added to the sol nano silica solution and left for 3 to 5 hours to induce precipitation, and then the precipitated sol nano silica Is filtered using filter paper. At this time, Al (OH) ₃ is preferably added 1 to 5 parts by weight based on 100 parts by weight of TEOS introduced in step 1.

In order to remove the ammonia component remaining on the surface of the filtered sol nano silica, 1 to 5 times diluted with an acid solution of hydrochloric acid, sulfuric acid, phosphoric acid or nitric acid solution diluted with 1%, and then distilled water It is preferable to wash 5-7 times using.

In step 3, secondary distilled water was added to the washed sol nano silica and stirred at 200 to 400 rpm for 1 hour at 60 to 80 ° C., followed by adding Al (OH) ₃ as a first catalyst and reacting for 1 hour. After the reaction, sulfuric acid (H ₂ SO ₄ ) was added as a second catalyst, gallium (Ga) oxide was added as a third catalyst, the mixture was stirred for 1 hour, the temperature was raised to 100 ° C., and the mixture was suspended for 24 hours. It is a catalyst attachment step of evaporating to obtain a dried solid.

The secondary distilled water is preferably added to 180 ~ 220 parts by weight based on 100 parts by weight of TEOS introduced in step 1.

The first catalyst Al (OH) ₃ is preferably added 1 to 100 parts by weight based on 100 parts by weight of TEOS introduced in step 1, if less than 1 part by weight of the number of acid sites involved in the chemical reaction is too small If there is more than 100 parts by weight, the density increases due to excessive increase of the acid point, there is a problem of offsetting the role of the acid point.

Sulfuric acid, which is the second catalyst, is preferably added in an amount of 1 to 15 parts by weight based on 100 parts by weight of Al (OH) ₃ added in Step 3, and when less than 1 part by weight is transferred, gamma alumina to alpha alumina is added during the reaction. There is a problem that can not be prevented, and if more than 15 parts by weight of the catalyst surface is over-coated with sulfuric acid has a problem of inhibiting the acid action supplied from alumina.

Preferably, the gallium (Ga) oxide as the third catalyst is added in an amount of 5 to 40 parts by weight based on 100 parts by weight of Al (OH) ₃ introduced in step 3, and when less than 5 parts by weight is added, the effect of increasing PFC gas decomposition efficiency is increased. There is a problem of falling, and when added in excess of 40 parts by weight there is a problem of reducing the performance of the alumina acid point.

The gallium oxide is not particularly limited, and Ga (NO ₃ ) ₃ may be used.

Induces the bonding of aluminum ions to the sol nano silica, and then the acid and gallium ions are bonded to the surface of the aluminosilica, a catalyst of carbon, chlorine, fluorine ions, etc. by VOCs present in the PFC gas treatment process. There is an advantage of providing a bonding structure that prevents loss and prevents thermal deformation and sublimation of acid components of aluminum at high temperatures.

The step 4 is a step of preparing a nano-oxidation catalyst by firing by heating the dried solid content for 5 to 12 hours at 550 ~ 800 ℃ while injecting air at 50 ~ 200cc / min in the kiln.

The present invention also provides a catalyst for the semiconductor process perfluorinated compound gas decomposition treatment having nano silica prepared by the above production method as a support.

Hereinafter, the constitution and effects of the present invention will be described in more detail through examples. These examples are only for illustrating the present invention, but the scope of the present invention is not limited by these examples.

Tetraethyl orthosilicate (TEOS) 80g, ammonia water (purity 30%) 50g, secondary distilled water was added to 1,000 g of ethanol with a purity of 90% or more and stirred for 6 hours at a temperature of 30 ° C. Was prepared.

3.4 g of Al (OH) ₃ was added to the sol nano-silica solution and stirred for 3 hours to induce precipitation, followed by filtration using 10 micro filter paper and washing three times with 1% phosphoric acid solution. It was washed six times using secondary distilled water.

160 g of secondary distilled water was added to the washed sol nano-silica and stirred at 300 rpm at 80 ° C. for 1 hour, and 0.8 g of Al (OH) ₃ was added and reacted for 1 hour, followed by sulfuric acid (H ₂ SO ₄ ) 0.1 After adding g, 0.16 g of Ga (NO ₃ ) ₃ was added and stirred for 1 hour. After the stirring was stopped and the temperature was raised to 100 ° C. and left for 24 hours to evaporate water, the obtained solid was calcined by heat treatment at 550 ° C. for 5 hours while injecting air at 100 cc / min in a calcination furnace to prepare a nano-oxidation catalyst. .

In Example 1, instead of adding 0.8 g of Al (OH) ₃ , 0.1 g of sulfuric acid (H ₂ SO ₄ ), and 0.16 g of Ga (NO ₃ ) ₃ , 20 g of Al (OH) ₃ and sulfuric acid (H ₂ SO ₄ ) A nano oxidation catalyst was prepared in the same manner except that 2.4 g and 4 g of Ga (NO ₃ ) ₃ were added.

In Example 1, instead of adding 0.8 g of Al (OH) ₃ , 0.1 g of sulfuric acid (H ₂ SO ₄ ), and 0.16 g of Ga (NO ₃ ) ₃ , 40 g of Al (OH) ₃ and sulfuric acid (H ₂ SO ₄ ) A nano oxidation catalyst was prepared in the same manner, except that 4.8 g and 8 g of Ga (NO ₃ ) ₃ were added.

In Example 1, instead of adding 0.8 g of Al (OH) ₃ , 0.1 g of sulfuric acid (H ₂ SO ₄ ), and 0.16 g of Ga (NO ₃ ) ₃ , 60 g of Al (OH) ₃ and sulfuric acid (H ₂ SO ₄ ) 7.2 g, except that 12 g of Ga (NO ₃ ) ₃ were added, except that the remainder was the same to prepare a nano oxidation catalyst.

In Example 1, instead of adding 0.8 g of Al (OH) ₃ , 0.1 g of sulfuric acid (H ₂ SO ₄ ), and 0.16 g of Ga (NO ₃ ) ₃ , 80 g of Al (OH) ₃ and sulfuric acid (H ₂ SO ₄ ) A nano oxidation catalyst was prepared in the same manner except that 9.6 g and 16 g of Ga (NO ₃ ) ₃ were added.

[Experimental Example 1]

SEM (Scanning Electron Microscope) pictures of the nano-oxidation catalyst prepared in Examples 1 to 5 are shown in Figures 1 to 5, wherein the magnification was 1 to 20,000 times.

As shown in FIGS. 1 to 5, it can be seen that as the catalyst loading on the nano-silica support increases, the nano-type structure is gradually decayed, and in FIG. 5, the structure is almost similar to that of ordinary amorphous particles. have.

[Experimental Example 2]

In order to analyze the waste gas decomposition performance of the nano-oxidation catalysts prepared in Examples 1 to 5, the decomposition performance of SF ₆ and CF ₄ was analyzed using the experimental equipment of FIG. 6.

In the experimental equipment for analyzing the waste gas decomposition performance of Figure 6, the total flow rate into the fixed bed reactor was 200cc / min, SF ₆ 1%, CF ₄ Each standard gas was injected to 1%, and 3 g of catalyst was charged in the fixed bed reactor, and the fixed bed reactor temperature was maintained at 750 ° C. The post-treatment of the experimental equipment was installed to prevent the contamination of the analyzer by the hydrofluoric acid (HF) generated after the reaction in SF ₆ and CF ₄ gas performance analysis, it was confirmed that does not affect the concentration of the injected waste gas components. . Results of the assay conducted under these conditions are shown in FIGS. 7 to 9.

Table 1 shows the results of the analysis of FIGS. 7 to 9 as numerical values.

Removal gas
Decomposition Efficiency (%) Example 1 Example 2 Example 3 Example 4 Example 5 SF ₆ 95 96 100 93 88 CF ₄ 90 93 98 86 76

Looking at Table 1, SF ₆ and CF ₄ in Example 3 The highest decomposition efficiency was shown for the gas, which is considered to be due to the effect of the surface generated by the contact of the catalysts supported on the spherical nano silica surface compared with the SEM photograph of FIG. 3.

Comparing Example 1 to Example 5, Example 1 shows a slightly higher efficiency, as shown in the SEM photographs of FIGS. 1 and 5, in which the wider surface provided by the spherical nano silica increases the efficiency. It can be seen that, in the case of Example 1, considering that the amount of supported catalyst compared to the case of Example 5, the catalysts impregnated therein are not involved in the waste gas decomposition in Example 5.

Semiconductor process based on nano silica according to the present invention The catalyst for gas decomposition treatment perfluorinated compound is PFC decomposition catalyst using spherical nano silica as a support, and PFC due to the physical effect of the sphere and surface provided by nano silica. The gas decomposition efficiency can be further enhanced, and by directly supporting and synthesizing three kinds of catalysts in the sol state of nano silica, the effect of the catalysts being combined with each other in the pores of the nanoparticles further increases the efficiency of waste gas decomposition. .

The catalyst of the present invention is a physicochemically improved catalyst which can increase the decomposition efficiency while reducing the use of expensive catalysts, compared to the conventional catalysts.

Claims (5)

Tetraethyl orthosilicate (TEOS), ammonia water and secondary distilled water were added to ethanol and stirred at 20 to 30 ° C. for 6 to 8 hours to prepare a sol nano silica solution (step 1);
Sol nano-silica surface treatment step (step 2) in which Al (OH) ₃ is added to the sol nano-silica solution to precipitate sol nano-silica, and the precipitated sol nano-silica is filtered and washed;
Second distilled water was added to the washed sol nano-silica and stirred at 200-400 rpm for 1 hour at 60-80 ° C., Al (OH) ₃ was added as a first catalyst and reacted for 1 hour. 2 was added sulfuric acid (H ₂ SO ₄ ) as a catalyst, the gallium oxide as a third catalyst was added and stirred for 1 hour, the temperature was raised to 100 ℃ to stand for 24 hours to evaporate water to obtain a dried solid Catalyst deposition step (step 3); And
Preparing the nano-oxidation catalyst by heat-treating the dried solids for 5 to 12 hours at 550 to 800 ° C. while injecting air into the firing furnace (step 4);
Method of producing a catalyst for semiconductor process perfluorinated compound gas decomposition treatment using a nano silica as a support, characterized in that it comprises a.
The method of claim 1, wherein in step 1,
60 to 100 parts by weight of tetraethyl orthosilicate (TEOS), 40 to 60 parts by weight of ammonia water, and 80 to 100 parts by weight of secondary distilled water are added to 1,000 parts by weight of ethanol. Method for producing a catalyst for gas decomposition treatment of perfluorinated compounds.
The method of claim 1, wherein in step 2,
The Al (OH) ₃ is 1 to 5 parts by weight based on 100 parts by weight of TEOS introduced in step 1, characterized in that the nano-silica as a support method for producing a catalyst for perfluoro compound gas decomposition treatment.
The method of claim 1, wherein in step 3,
The first catalyst Al (OH) ₃ is added 1 to 100 parts by weight based on 100 parts by weight of TEOS introduced in step 1, the second catalyst sulfuric acid is 100 parts by weight of Al (OH) ₃ added in step 3 1 to 15 parts by weight with respect to, and the third catalyst gallium oxide is added to the nano silica as a support, characterized in that 5 to 40 parts by weight based on 100 parts by weight of Al (OH) ₃ added in step 3. Method for producing a catalyst for semiconductor gas perfluorine decomposition process.
A catalyst for the semiconductor process perfluorinated compound gas decomposition treatment, which is prepared by the method according to any one of claims 1 to 4, wherein the support is made of nano silica.

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