JP7014647B2 - A break filter and a method for producing a silicon carbide porous body used in the break filter. - Google Patents

Description

The present invention relates to a break filter (also referred to as a diffuser) and a method for manufacturing a silicon carbide porous body used in the break filter. The present invention relates to a break filter installed at a gas inlet and a method for producing a silicon carbide porous body suitable for the break filter .

In the semiconductor manufacturing process, the inside of the processing apparatus is depressurized and heat treatment is performed under the reduced pressure. Then, when this heat treatment is completed, the inside of the processing apparatus is returned from the reduced pressure state to the atmospheric pressure, and the semiconductor wafer is taken out.
In such a semiconductor processing device, when the wafer to be processed is carried in from the outside or the processed wafer is carried out to the outside, the atmosphere inside the processing device is usually matched with the external atmosphere. , A gas introduction port and a gas exhaust port are provided. The gas introduction port and the gas exhaust port are configured to discharge the atmospheric gas in the processing device to a reduced pressure state, and to introduce a gas to release the reduced pressure state.

The schematic configuration of this semiconductor processing apparatus will be described with reference to FIG.
As shown in FIG. 3, the semiconductor processing device 50 is provided with a gas introduction device 60 that introduces gas to release the depressurized state. When a gas introduction device (break filter) 60 is used for the gas introduction port, the pressure fluctuation at the moment when the on-off valve 51 is opened can be alleviated, so that there is an effect of suppressing the flying of particles in the device. Further, when exhausting the inside of the device, a fine adjustment valve 53 is provided in parallel with the on-off valve 52 for exhaust, and slow exhaust is realized by operating the fine adjustment valve 53 at the start of exhaust. The reference numeral W in the inside is the wafer to be processed.

In the gas introduction device (break filter) 60 used in this way, as shown in FIG. 4, the filter element 61 has a polytetrafluoroethylene (PTFE) gasket 63, 63 between the pair of metal spacers 62a, 62b. It is attached via. Further, a ventilation pipe 65 having a hollow metal shape and having a large number of ventilation holes 64 formed around it is provided and penetrates the spacer 62a and the filter element 61.

In order to release the reduced pressure state by the gas introduction device (break filter) 60, the on-off valve 51 is first opened, and gas is introduced from the ventilation pipe 65 on the spacer 62b side. This gas is introduced into the processing device via the vent 64 and the filter element 61. At this time, the filter element 61 becomes a resistance, the flow velocity is decelerated, and the depressurized state is gradually released.
In this way, the speed at which the gas flows into the processing device is slowed down, and the flying up of particles in the processing device and the generation of dew condensation are suppressed.

By the way, as the material of the filter element 61 in the gas introduction device 60 (break filter), a filter material made of metal particles such as nickel (Patent Document 1), a filter material made of a resin such as PTFE, alumina, silica or the like can be used. Filter media made of ceramics are commonly used. Further, Patent Document 2 discloses a break filter using a silicon carbide porous material as a filter material.

Special Table 2012-530592A Gazette Japanese Patent No. 5032937

However, when a filter material made of metal particles such as nickel is used as the material of the filter element 61, there is a problem that corrosion proceeds due to a gas introduced into the load lock, for example, a corrosive gas. Further, when alumina ceramics are used as a filter material, the corrosion resistance of alumina itself is high, but there is a problem that the corrosion resistance is lowered due to additives and unavoidable impurities added as auxiliary agents. Further, when silica ceramics are used as a filter material, there is a problem that the corrosion resistance to a fluorine-based gas is inferior. Further, when PTFE is used as a filter material, there is a problem that the strength and heat resistance are inferior.

As a solution to the problems such as corrosion resistance and heat resistance, it is conceivable to use the silicon carbide porous material disclosed in Patent Document 2 as the filter material.
However, the break filter disclosed in Patent Document 2 has a problem that it is insufficient in terms of particle collection performance and particle fly-up prevention performance because of its large pore diameter and porosity.
Further, in order to solve the above-mentioned problems, if the pore diameter of the silicon carbide porous body is reduced, the porosity is reduced, and the particle collection performance and the particle soaring prevention performance are improved, but the pressure loss is increased and the inside of the container is filled. Another problem was that it took longer to return to atmospheric pressure.

Therefore, the inventor of the present application presupposes that a silicon carbide porous body having excellent corrosion resistance and heat resistance is used as the filter material for the break filter, in order to solve the problems of the invention disclosed in Patent Document 2. Diligent research has led to the invention of the present application.

The present invention has been made under the above circumstances, and has particle collection performance and particle soaring prevention performance in a break filter installed at a gas inlet in order to return the inside of a container under reduced pressure to atmospheric pressure. It is an object of the present invention to provide a break filter capable of returning the inside of a container to atmospheric pressure in a short time, and a method for producing a silicon carbide porous body used for the break filter .

The break filter according to the present invention made to achieve the above object is a break filter provided with a filter element made of a silicon carbide porous body, which is installed at a gas inlet of a semiconductor manufacturing apparatus, and the filter element is , A plurality of silicon carbide particles are bonded to each other to form a skeleton, and a plurality of pores are formed, and the adjacent silicon carbide particles have a neck portion formed by surface contact with each other, and the average pore diameter is large. It is characterized by being composed of a silicon carbide porous body having a porosity of 35% or more and 55% or less, which is larger than 3 μm and 9 μm or less.
By using the silicon carbide porous material configured in this way for the break filter installed in the gas inlet of the semiconductor processing device, excellent particle collection performance and particle soaring can be achieved while ensuring a sufficient gas flow rate. Prevention performance can be obtained. Further, by having the neck portion, sufficient strength can be given.

Further, the method for producing a silicon carbide porous body according to the present invention, which has been made to achieve the above object, is a method for producing a silicon carbide porous body used for a break filter installed in a gas inlet of a semiconductor processing apparatus. A step of adding and mixing an organic binder to silicon carbide particles having an average particle diameter of 0.5 μm or more and 5 μm or less and firing in a non-oxidizing atmosphere after molding is provided, and the firing temperature is 2200 ° C. or higher and 2400 ° C. It is characterized by the following.
The silicon carbide particles having an average particle diameter of 0.5 μm or more and 5 μm or less are a mixture of silicon carbide fine particles having an average particle diameter of less than 1 μm and silicon carbide particles having an average particle diameter of 1 μm or more, and have an average particle diameter of less than 1 μm. The silicon carbide fine particles in the above are preferably 10 wt% or more and 20 wt% or less of the total silicon carbide particles.

By producing the silicon carbide porous body by such a method, the silicon carbide porous body according to the present invention can be obtained.

Further, after the step of adding and mixing an organic binder to the silicon carbide raw material having an average particle diameter of 0.5 μm or more and 5 μm or less, molding and firing, the mixture is further heated at a temperature of 1000 ° C. or higher and 1300 ° C. or lower in an oxidizing atmosphere. It is preferable to process.
By performing the oxidative heat treatment in the above temperature range in this way, an oxide film is formed on the surface of silicon carbide, and cracks that can become defects are filled and repaired. As a result, the strength as a porous body can be increased by about twice.

According to the present invention, in order to return the inside of the container under reduced pressure to atmospheric pressure, the break filter installed at the gas inlet secures the particle collection performance and the particle soaring prevention performance, and shortens the inside of the container. It is possible to provide a break filter capable of returning to atmospheric pressure in time, and a method for producing a silicon carbide porous body used in the break filter .

FIG. 1 is an SEM image showing the skeletal structure of the first embodiment of the silicon carbide porous body according to the present invention. FIG. 2 is an SEM image showing the skeletal structure of the second embodiment of the silicon carbide porous body according to the present invention. FIG. 3 is a block diagram showing a schematic configuration of a semiconductor processing apparatus. FIG. 4 is a block diagram showing a schematic configuration of a gas introduction device (break filter).

Hereinafter, embodiments of the silicon carbide porous body (filter element of the break filter) and the method for manufacturing the same according to the present invention will be described with reference to the drawings.
FIG. 1 is an SEM (scanning electron microscope) image showing the skeletal structure of the first embodiment of the silicon carbide porous body according to the present invention.

The silicon carbide porous body 1 shown in FIG. 1 is made of silicon carbide (SiC), and a plurality of silicon carbide particles are bonded to form a skeleton, and a large number of pores are formed between them. The average pore diameter of the silicon carbide porous body 1 is larger than 3 μm and 9 μm or less (preferably larger than 3 μm and 6 μm or less), and the porosity is 35% or more and 55% or less.
The mercury intrusion method was used to measure the average pore diameter. In addition, the SEM image analysis method was used to measure the average particle size of the silicon carbide particles.

Further, as shown in the image of FIG. 1, adjacent silicon carbide particles 2 are in surface contact with each other, and a neck portion 3 is formed at the connecting portion thereof. Since the neck portion 3 is formed, it can be provided with sufficient strength to withstand use as a filtering material.

When the average pore diameter is 3 μm or less, the pressure loss is large and the gas supply amount is small. Therefore, the time required to reach the atmospheric pressure becomes significantly longer. On the other hand, if the average pore diameter is larger than 9 μm, the particle collection performance and the particle fly-up prevention function are deteriorated, and there is a problem that the wafer manufacturing yield is lowered.

Further, when the porosity is smaller than 35%, the gas supply amount becomes small and the time until the atmospheric pressure is reached becomes significantly long. On the other hand, when the porosity is larger than 55%, the particle flying prevention performance is lowered and the wafer manufacturing yield is lowered.

By using the silicon carbide porous body 1 thus formed as a break filter, it is possible to collect particles and sufficiently prevent the particles from flying up while ensuring a sufficient gas flow rate.

In order to produce the silicon carbide porous body 1, an organic binder is added to a silicon carbide raw material having an average particle diameter of 0.5 μm to 5 μm, mixed, and calcined in a non-oxidizing atmosphere after molding. Baking is carried out at 2200 ° C to 2400 ° C for, for example, 2 hours. The reason why the average particle size of the silicon carbide raw material is 0.5 μm to 5 μm is that if it is smaller than 0.5 μm, the porosity becomes small, the gas supply amount becomes small, and the time until the atmospheric pressure is reached becomes significantly long. If it is larger than 5 μm, the pore diameter becomes large and the particle collection performance and the particle soaring prevention function are deteriorated.

It is possible to obtain a fired body by heating at 2000 ° C to 2200 ° C, but in that case, the grain growth becomes insufficient and silicon carbide fine powder remains, which becomes a dust generation source and has a pore diameter. It becomes smaller and the amount of gas supplied decreases. Further, the growth of the neck portion 3 is not sufficient, and the strength is also insufficient.

When the firing temperature is set to 2200 ° C. to 2400 ° C. as described above, the silicon carbide fine powder is vaporized, or the silicon carbide fine powder is deposited and aggregated on the neck portion and disappears. Furthermore, the strength is also improved.
When the firing temperature is higher than 2400 ° C., the grain growth progresses, the pore diameter becomes large, the particle collection performance and the particle flying prevention function are deteriorated, and the strength is lowered.
The silicon carbide particles having an average particle diameter of 0.5 μm or more and 5 μm or less are a mixture of silicon carbide fine particles having an average particle diameter of less than 1 μm and silicon carbide particles having an average particle diameter of 1 μm or more. By setting the silicon fine particles to 10 wt% or more and 20 wt% or less of the entire silicon carbide particles, the ratio of the size of the entire silicon carbide particles is appropriately controlled, and the target pores and skeletal structure can be easily formed.

As described above, according to the first embodiment of the present invention, in the silicon carbide porous body 1, the average pore diameter is larger than 3 μm and 9 μm or less (preferably larger than 3 μm and 6 μm or less), and the porosity is 35%. By setting the content to 55% or less, it is possible to obtain excellent particle collection performance and particle soaring prevention performance while ensuring a sufficient gas flow rate.

Subsequently, a second embodiment according to the present invention will be described. In this second embodiment, the silicon carbide porous body 1 obtained in the first embodiment is further subjected to an oxidation treatment by heating.
That is, the obtained silicon carbide porous body 1 is heat-treated in an oxidizing atmosphere of 1000 ° C. to 1300 ° C. for, for example, 2 hours. The silicon carbide porous body 10 obtained by this oxidation treatment is shown in FIG. FIG. 2 is an SEM (scanning electron microscope) image showing the skeletal structure of the second embodiment of the silicon carbide porous body according to the present invention.

This oxidation treatment doubles the strength of the porous body. It is considered that this is because an oxide film (preferably a film thickness of 50 nm to 200 nm) is formed on the SiC surface by the heat treatment, and cracks that can become defects are filled and repaired.
By increasing the strength by this heat treatment, the gas supply pressure increases and the gas flow rate can be increased, so that the time until the depressurized container returns to the atmospheric pressure can be shortened.

In the heat treatment for increasing the strength, if the heating temperature is lower than 1000 ° C., the oxide film thickness becomes thin and the strength improving effect becomes insufficient. On the other hand, when the heating temperature is higher than 1300 ° C., the oxide film thickness becomes thicker, but the defect filling and repairing effects are saturated, and no further strength effect is observed. Further, the oxide film that has become too thick is easily peeled off from the SiC surface due to the difference in the thermal expansion rate and becomes a dust generation source.

As described above, according to the second embodiment of the present invention, the silicon carbide having an average pore diameter of more than 3 μm and 9 μm or less (preferably larger than 3 μm and 6 μm or less) and a porosity of 35% or more and 55% or less. By performing oxidation heat treatment on the porous body 1 at a predetermined temperature, the strength becomes higher, the particle collection performance and the particle soaring prevention performance are excellent, and the time from decompression of the chamber to return to atmospheric pressure can be shortened. A porous body 10 can be obtained.

Subsequently, the silicon carbide porous body according to the present invention will be further described based on Examples.
In this example, the effect was verified by producing a silicon carbide porous body having the constitution shown in the above embodiment.

(Experiment 1)
In Experiment 1, the corrosion resistance of the silicon carbide porous body used as the material of the filter element in the present invention was verified.

OY-15 (manufactured by Yakushima Denko Co., Ltd.) was used as a sample as the silicon carbide porous body to be verified in Experiment 1.
Then, the sample of this porous body was immersed in a 10% HF solution (22 ° C.) for 15 hours, and the amount of component elution (μg / g) per 1 g of the sample was measured.
Further, the porous sample was immersed in a 10% HCI solution (22 ° C.) for 15 hours, and the amount of component elution (μg / g) per 1 g of the sample was measured.
Further, the porous sample was immersed in a HBr10% solution (22 ° C.) for 15 hours, and the amount of component elution (μg / g) per 1 g of the sample was measured.

Further, as Reference Example 1, a sample of a diffuser element (Ni element) manufactured by Company A was immersed in a 10% HF solution (22 ° C.) for 15 hours, and the amount of component elution (μg / g) per 1 g of the sample was measured.
Further, a sample of a diffuser element (Ni element) manufactured by Company A was immersed in an Hcl 10% solution (22 ° C.) for 15 hours, and the amount of component elution (μg / g) per 1 g of the sample was measured.
Further, a sample of a diffuser element (Ni element) manufactured by Company A was immersed in an HBr 10% solution (22 ° C.) for 15 hours, and the amount of component elution (μg / g) per 1 g of the sample was measured.

Further, in Reference Example 2, the sample was immersed in an alumina porous body in a 10% HF solution (22 ° C.) for 15 hours, and the amount of component elution (μg / g) per 1 g of the sample was measured.
Further, the sample was immersed in an alumina porous body in a Hcl 10% solution (22 ° C.) for 15 hours, and the amount of component elution (μg / g) per 1 g of the sample was measured.
Further, the sample was immersed in an alumina porous body in a 10% HBr solution (22 ° C.) for 15 hours, and the amount of component elution (μg / g) per 1 g of the sample was measured.

The results of Experiment 1 are shown in Table 1. As a result, elution of Fe, Cr, Cu, and Ti was observed from the diffuser element manufactured by Company A (Reference Example 1), and elution of Ca and Ti was observed from the alumina porous body (Reference Example 2).
On the other hand, only a small amount of Ti elution was observed from the silicon carbide porous body, and it was confirmed that the corrosion resistance was excellent.

(Experiment 2)
In Experiment 2, the characteristics when the silicon carbide porous material (first embodiment) according to the present invention was used as a break filter were verified.
In this experiment 2, 2 parts by weight of PVA (polyvinyl alcohol) was added as a binder to 100 parts by weight of a silicon carbide raw material having an average particle size in a predetermined range, and the mixture was mixed with water. This was dried and then crushed, and the molded product obtained by mold molding was fired at a predetermined temperature for 2 hours. The porous body thus obtained had different average pore diameters and average porosities by changing the conditions of the particle diameter and the heating temperature.

Then, a plurality of types of samples were selected from the obtained porous bodies, and filters having a diameter of 48 mm and a thickness of 5 mm were formed from them (Examples 1 to 7 and Comparative Examples 1 to 6).
Table 2 shows the conditions of Experiment 2.

Table 3 shows the characteristics when the porous bodies of Examples 1 to 7 and Comparative Examples 1 to 6 are used as break filters.
In Table 3, the gas flow rate (L / min) indicates the amount of gas that has passed through the porous body by flowing _N2 gas through the porous body having a diameter of 48 mm and a thickness of 5 mm at a supply pressure of 0.2 MPa.
The number of dust generated indicates the number of particles generated from the porous body by flowing air through the porous body having a diameter of 48 mm and a thickness of 5 mm.
Further, the particle collection performance indicates the ratio of particles that have passed through the porous body by flowing a gas containing particles of 30 nm through the porous body having a diameter of 48 mm and a thickness of 5 mm. In the particle collection performance data, N represents 9, and the numerical value before that represents the number of consecutive 9s. (Example: 3N = 99.9%)
Further, the particle soaring prevention performance indicates the number of particles soared by sprinkling quartz powder (diameter 30 to 60 μm) in the chamber and returning from the vacuum to the atmosphere.

From the results shown in Table 3, it was confirmed that in Examples 1 to 7, the particle collection performance and the particle soaring prevention performance were excellent while ensuring a sufficient gas flow rate. It was also confirmed that the average pore diameter at that time was larger than 3 μm and 9 μm or less, and the porosity was 35% or more and 55% or less.
Further, an organic binder of less than 1 μm is added to a silicon carbide raw material having an average particle diameter of 0.5 μm or more and 5 μm or less, mixed, and calcined at a temperature of 2200 ° C. or more and 2400 ° C. or less after molding to obtain the average pore size and porosity. It was confirmed that a silicon carbide porous body having the above can be obtained.

(Experiment 3)
In Experiment 3, the silicon carbide porous body (first embodiment) according to the present invention was further oxidatively heated to verify the characteristics of the filter on which the oxide film was formed.
In this experiment 3, a silicon carbide porous body having an average porosity of 5 μm and an average porosity of 40% was formed based on the first embodiment.
The obtained porous body was subjected to oxidative heat treatment for 2 hours under the condition of heating temperature to form a filter having a diameter of 48 mm and a thickness of 5 mm, and its characteristics were verified.
Table 4 shows the conditions and characteristic results of Experiment 3.

From the results in Table 4, the porous body obtained in the first embodiment is further heat-treated at 1000 ° C. or higher and 1300 ° C. or lower to maintain excellent particle collection performance and particle fly-up prevention performance. It was confirmed that the strength could be further increased. The gas flow rate in Table 4 is higher than that in Table 3 because the gas can be flowed at high pressure due to the improvement in strength.

From the experimental results of the above examples, the silicon carbide porous material according to the present invention is excellent in particle collection performance and particle fly-up prevention performance, and it takes a short time from decompression of the installation chamber to return to atmospheric pressure. Confirmed that it can be done.

1 Silicon Carbide Porous Medium 2 Silicon Carbide Particles 3 Neck 10 Silicon Carbide Porous Medium

Claims (4)

A break filter equipped with a filter element made of a silicon carbide porous material, which is installed at the gas inlet of a semiconductor manufacturing apparatus.
The filter element is
A plurality of silicon carbide particles are bonded to each other to form a skeleton, and a plurality of pores are formed, and the adjacent silicon carbide particles have a neck portion formed by surface contact with each other, and the average pore diameter is 3 μm. It is composed of a silicon carbide porous body having a porosity of 35% or more and 55% or less, which is larger than 9 μm.
A break filter that features that. A method for manufacturing a silicon carbide porous body used for a break filter installed in a gas inlet of a semiconductor processing apparatus.
A silicon carbide porous body characterized by adding and mixing an organic binder to silicon carbide particles having an average particle diameter of 0.5 μm or more and 5 μm or less, and firing at 2200 ° C. or more and 2400 ° C. or less in a non-oxidizing atmosphere after molding. Manufacturing method. The silicon carbide particles having an average particle diameter of 0.5 μm or more and 5 μm or less are a mixture of silicon carbide fine particles having an average particle diameter of less than 1 μm and silicon carbide particles having an average particle diameter of 1 μm or more, and are carbonized with an average particle diameter of less than 1 μm. The method for producing a silicon carbide porous body according to claim 2 , wherein the silicon fine particles are 10 wt% or more and 20 wt% or less of the total silicon carbide particles. After the step of adding and mixing an organic binder to the silicon carbide raw material having an average particle diameter of 0.5 μm or more and 5 μm or less, and firing after molding,
The method for producing a silicon carbide porous body according to any one of claims 2 to 3 , further comprising heat treatment at a temperature of 1000 ° C. or higher and 1300 ° C. or lower in an oxidizing atmosphere.

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