KR102611746B1 - Clean booth for silicon polycrystalline filling work - Google Patents

Abstract

The present invention is a clean booth for filling silicon polycrystals in a quartz crucible, and the clean booth is sealed by the ceiling (or ceiling), sides, and floor (or top). It has an entrance disposed on the side, a fan/filter device disposed on the ceiling, and an exhaust port disposed at the lower part of the side, and the fan/filter device blows clean air into the clean booth, and purifies the air inside the clean booth. By discharging air from the exhaust port and returning it to the fan/filter device, the air inside the clean booth is circulated and the pressure inside the clean booth when the entrance is opened is controlled to be the same pressure or negative pressure with respect to the pressure outside the clean booth. This is a clean booth for silicon polycrystalline charging work, characterized by having a control mechanism. Accordingly, when manufacturing silicon single crystals, a clean booth is provided that does not contaminate the surrounding area due to dust generated in the process of filling silicon polycrystals into a raw material container.

Description

Clean booth for silicon polycrystalline filling work

The present invention relates to a clean booth used in the process of filling a raw material container with silicon polycrystals used as a molten raw material when producing an ingot, especially a silicon single crystal by the CZ method or the like.

Conventionally, silicon single crystals are mainly manufactured by the CZ method. In the CZ method, first, silicon polycrystalline raw material is filled in a raw material container, and the raw material is melted by heating with a graphite heater. A silicon single crystal is grown by immersing the seed crystal attached to the lower end of the upper shaft into the molten raw material and pulling it up at low speed while rotating the upper shaft. The raw material container is generally a quartz glass crucible (hereinafter referred to as a quartz crucible).

Since it is necessary to charge the silicon polycrystal in the quartz crucible in a clean state, it is generally filled in the quartz crucible in a room (hereinafter referred to as raw material preparation room) different from the space (impression room) where the single crystal pulling device is installed. Due to the recent increase in diameter of silicon single crystals and miniaturization of semiconductor devices, it is necessary to use large-diameter quartz crucibles and to perform the silicon polycrystal filling process into the quartz crucible in an environment that is less polluted by dust, etc. there is.

In Patent Document 1, which is a prior art, the loading operation is performed in a clean booth or clean bench to prevent particle contamination inside and outside the lifting device, and the upper opening of the raw material container is transported with the cover closed, so that the raw materials, etc. in the raw material container are removed. It is disclosed to prevent particle contamination of the impression room generated from contamination or raw materials, and dust generated from the raw materials during the loading operation (state before closing the cover on the upper opening of the raw material container) is inside the clean booth or clean bench. There is a problem of contamination of the area around the clean booth or raw material preparation room due to the exhaust air discharged from the opening of the clean booth or clean bench, or the air discharged when the entrance to the clean booth is opened and closed to transport the raw material container.

For example, Figure 3 is a cross-sectional view showing an example of a conventional open clean booth for silicon polycrystalline charging work. Conventionally, the raw material preparation room is generally set to have a higher cleanliness level than the impression room, such as ISO cleanliness class (4) or class (5), and the filling operation of silicon polycrystalline (18') into the quartz crucible (17'), This is carried out on a clean bench installed in the raw material preparation room or in an open clean booth 1'.

The silicon polycrystal (18'), stored in a clean plastic bag, for example, is opened for charging into a quartz crucible (17') and filled into the quartz crucible (17'). In the open clean booth 1', for example, the side of the clean booth 1' is covered with a vinyl sheet 22, etc., and the outside air 13' (clean air from the raw material preparation room) is blown through a fan and filter device. (3') (FFU) is sucked in, and clean air (11') is again supplied into the device, so the inside of the device is pressurized compared to the raw material preparation room. The pressurized air within the device is discharged as air 23 outside the device through an opening provided at the bottom of the vinyl sheet 22 covering the side of the clean booth 1'. For example, when the plastic bag is opened and the silicon polycrystal 18' is charged into the quartz crucible 17', dust generated from the silicon polycrystal 18' flows out of the open clean booth 1' into the device. In addition, it is discharged together with the discharged air (23), and causes the problem of contaminating other devices or jigs installed in the raw material preparation room, or the stored quartz crucible before charging the silicon polycrystal, or the quartz crucible in which the silicon polycrystal has been completely filled. I have done it. Particularly in recent years, when semiconductor devices are becoming more miniaturized, the effects of contamination of quartz crucibles and jigs are becoming more evident, and as a countermeasure against such contamination, it is necessary to install clean booths for storing quartz crucibles and jigs, for example. It has been poetic.

Japanese Patent Publication No. H7-172975

The present invention was made in consideration of the above problems, and when manufacturing silicon single crystals by the CZ method (Czochralski method), etc., due to the dust generated in the process of filling the silicon polycrystal used as a molten raw material into the raw material container. The purpose is to provide a clean booth that does not pollute the surroundings.

In order to solve the above problem, the present invention is a clean booth for filling silicon polycrystals into a quartz crucible. This clean booth has a ceiling (or ceiling), side and floor (or top) surfaces. It is sealed by a door, has an entrance located on the side, a fan and filter device located on the ceiling, and an exhaust port located on a lower part of the side, and the fan and filter are located on the ceiling. By blowing clean air into the clean booth by a device, exhausting the air in the clean booth through the exhaust port, and returning the exhausted air to the fan and filter device, the air inside the clean booth is circulated, A silicon polycrystal comprising a control mechanism that forms a downflow in a clean booth and controls the pressure inside the clean booth when the entrance is opened to be the same pressure or negative pressure with respect to the pressure outside the clean booth. A clean booth for charging work is provided.

In such a clean booth for silicon polycrystal charging work, during the silicon polycrystal charging work into the quartz crucible, for example, when opening the plastic bag and charging the silicon polycrystal into the quartz crucible, dust generated from the silicon polycrystal is removed from the booth. It is possible to provide a closed clean booth that does not vent to the outside and to suppress contamination in the raw material preparation room.

At this time, the control mechanism preferably controls the pressure difference between the inside of the clean booth and the outside of the clean booth to be -2 to 0 Pa when the entrance is opened.

With such a clean booth for silicon polycrystalline filling work, when the entrance to the clean booth is opened, dust generated within the sealed clean booth is not discharged outside the device, and other devices or jigs installed in the raw material preparation room, or stored silicon, are not discharged outside the device. It is possible to prevent contamination of quartz crucibles before filling with polycrystals or quartz crucibles that have been filled with silicon polycrystals.

In addition, the control mechanism includes a door switch sensor for issuing a command to open the entrance, a control unit that receives a command to open the entrance from the door switch sensor, and an intake amount of air outside the device to the clean booth. It has an intake damper for adjusting, a blowing damper for adjusting the amount of air blowing from the fan/filter to the inside of the clean booth, and a differential pressure sensor for detecting a pressure difference between the inside of the clean booth and the outside of the clean booth, wherein the control unit receives a command to open the entrance from the door switch/sensor, reduces the output of the fan/filter device before opening the entrance, and adjusts the opening degree of the intake damper and the opening degree of the blowing damper to It is preferable to adjust the pressure inside the clean booth by varying it, and to open the entrance after checking the pressure difference between the inside of the clean booth and the outside of the clean booth by the differential pressure sensor.

With such a clean booth for silicon polycrystalline filling work, the pressure inside the clean booth when the entrance is opened can be easily and reliably set to the same pressure or negative pressure as the outside, and other devices or jigs installed in the raw material preparation room or stored. It is possible to further prevent contamination of the quartz crucible before filling with silicon polycrystal or the quartz crucible after filling with silicon polycrystal.

In addition, it has an air conditioning line for blowing in a part of the air outside the device taken in by the air intake damper and the air exhausted from the exhaust port, and a clean room air conditioning device connected to this air conditioning line, and the clean room air conditioning device , it is preferable to air-condition some of the air outside the device and the exhausted air blown in from the air conditioning line, and supply this air-conditioned air to the fan and filter device.

With such a clean booth for silicon polycrystalline filling work, it is possible to suppress deterioration of the working environment due to internal lighting of the sealed clean booth or heat generation by workers.

With the clean booth for silicon polycrystal charging work of the present invention, during the charging work of silicon polycrystal, for example, when opening a plastic bag and charging silicon polycrystal into a quartz crucible, dust generated from silicon polycrystal is discharged out of the device. It is possible to provide an airtight clean booth and suppress contamination in the raw material preparation room. Therefore, it becomes possible to carry out the filling process of silicon polycrystal into the quartz crucible in an environment that is less polluted by dust or the like.

Figure 1 is a cross-sectional view showing an example of a closed clean booth for silicon polycrystalline charging work according to the present invention.
Figure 2 is a perspective view showing an example of a closed clean booth for silicon polycrystalline charging work according to the present invention.
Figure 3 is a cross-sectional view showing an example of a conventional open clean booth for silicon polycrystalline charging work.
Figure 4 is a top view (a) showing the raw material preparation room equipped with a clean booth in the example, and a top view (b) showing the raw material preparation room equipped with a clean booth in Comparative Example 1. .

As described above, in the conventional clean booth for silicon polycrystalline charging work, the inside of the clean booth or clean bench is contaminated due to dust generated from the raw material during the loading operation (state before closing the cover on the upper opening of the raw material container), There was a problem of contamination around the clean booth or raw material preparation room due to exhaust air discharged from the opening of the clean booth or clean bench, or air discharged when the entrance to the clean booth was opened and closed to transport raw material containers.

In addition, the present inventors have conducted extensive studies to solve the above problems, and as a result, it is a closed clean booth in which dust generated from the silicon polycrystal is not discharged outside the booth when silicon polycrystal is filled in the raw material container, and the clean booth is It was discovered that it is possible to suppress contamination around the clean booth or raw material preparation room by having a control mechanism that controls the pressure inside the clean booth to be equal or negative to the pressure outside the clean booth when opening the entrance. Thus, the present invention was reached.

That is, the device of the present invention is a clean booth for filling silicon polycrystals into a quartz crucible, and this clean booth has a ceiling (or ceiling), side and floor (or top) surfaces. ), has an entrance disposed on the side, a fan and filter device disposed on the ceiling, and an exhaust port disposed at a lower portion of the side, and is sealed by the fan and filter device disposed on the ceiling. By blowing clean air into the clean booth, exhausting the air inside the clean booth through the exhaust port, and returning the exhausted air to the fan/filter device, the air inside the clean booth is circulated, and the air inside the clean booth is circulated. It has a control mechanism that forms a downflow and controls the pressure inside the clean booth when the entrance is opened to be the same pressure or negative pressure with respect to the pressure outside the clean booth.

Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

First, the clean booth for silicon polycrystalline charging work of the present invention will be described. 1 is a cross-sectional view showing an example of a closed clean booth for silicon polycrystalline charging work according to the present invention. Additionally, Figure 2 is a perspective view showing an example of a closed clean booth for silicon polycrystalline charging work according to the present invention. The clean booth for silicon polycrystalline filling work is located in a clean raw material preparation room.

As described above, as shown in FIGS. 1 and 2, the sealed clean booth 1 has side and ceiling surfaces (or ceiling surfaces) that are aligned with the panel and the floor surface (or top surface). )) is completely sealed, and an entrance (20) is provided on the side. In order to increase air conditioning efficiency, it is desirable to maintain high airtightness of the panel using a high-insulation panel for clean rooms and sealant for clean rooms, and that the entrance 20 be an automatic door equipped with a resin belt drive or dustproof cover on the movable part to prevent dust generation. In addition, an exhaust port 4 is provided within a height of 300 mm from the floor surface (or top surface) on a side other than the side where the entrance 20 is provided, and a fan/filter device connected by a circulation line 14 (3) The air 10 exhausted by the (FFU) is circulated and clean air 11 is supplied into the clean booth to form a downflow (laminar flow). In addition, in order to suppress deterioration of the working environment due to internal lighting of the sealed clean booth (1) or heat generation by workers (21), part of the exhausted air (10) is branched to the air conditioning line (15) and used for clean room use. It is also possible to condition the air with the air conditioning device (2) and supply it to the fan/filter device (3). Furthermore, in addition to blowing in fresh air outside the device (13) (clean air from the raw material preparation room) for workers, clean exhaust air (12) is used to prevent the inside of the sealed clean booth (1) from being overly pressurized compared to the raw material preparation room other than the booth. emits. The air outside the device (13) and the clean exhaust air (12) are connected to the intake damper (8) and the differential pressure sensor (7) that detects the pressure difference between the inside of the clean booth (1) and the outside of the clean booth (1). The opening degree of the blowing damper 9 is adjusted, and is controlled to about -2 to +2 Pa when the entrance 20 is closed. On the other hand, since the clean exhaust air 12 directly discharges clean air that has passed through the fan/filter device 3 from a position at a predetermined height that is not affected by dust generation, There is no contamination in the raw material preparation room.

The entrance 20 is used to fill the quartz crucible 17 with the silicon polycrystal 18, when the quartz crucible 17, the silicon polycrystal 18, and other charging jigs are brought into the sealed clean booth 1, Alternatively, it is opened when the quartz crucible 17 with the silicon polycrystal 18 completely charged is taken out. The clean booth (1) of the present invention has a control mechanism (25) for controlling the pressure inside the clean booth when the entrance (20) of the clean booth (1) is opened. In this control mechanism (25), an opening command for the entrance (20) is transmitted to the control unit (19) by a door switch/sensor (6). The control unit 19 immediately lowers the motor output of the fan/filter device 3 to reduce the amount of circulating air and at the same time controls the ventilation damper 9 to adjust the discharge amount of the clean exhaust air 12, and the air outside the device 13. ), the opening degree of the intake damper (8), which adjusts the air supply amount, is varied, and the differential pressure detected by the differential pressure sensor (7) is set to -2 to 0 Pa, that is, the inside of the sealed clean booth (1) is the same pressure as the raw material preparation room or The pressure is slightly reduced compared to the raw material preparation room. After confirming that the differential pressure sensor 7 indicates -2 to 0 Pa of the above conditions, the control unit 19 opens the entrance 20 and enables the carrying in and out of the quartz crucible 17, silicon polycrystal 18, etc. do. As described above, by setting the differential pressure between the sealed clean booth 1 and the raw material preparation room to -2 to 0 Pa, for example, opening of a plastic bag and silicon polycrystalline 18 can occur within the sealed clean booth 1. When charging into the quartz crucible 17, dust from the silicon polycrystal 18 is not discharged outside the device, and other devices or jigs installed in the raw material preparation room or the stored silicon polycrystal 18 are not discharged outside the device before charging. Contamination of a quartz crucible or a quartz crucible filled with silicon polycrystalline (18) can be prevented.

In addition, in the sealed clean booth (1) of the present invention, the static electricity removal device (16) is provided so that dust is difficult to be adsorbed on the panel, and the bottom surface (or top surface (or An exhaust port (4) is provided within a height of 300 mm from the ceiling, the air (10) exhausted by the fan/filter device (3) is circulated, and clean air (11) is supplied to achieve downflow (laminar flow). By forming it, dust can be efficiently removed. Additionally, by installing a detachable primary filter (5) in the exhaust port (4), in addition to easily collecting dust, the filter life of the fan/filter device (3) can be extended. The static electricity eliminator 16 may be equipped with, for example, an ionizer, and the generation of static electricity can be suppressed by humidifying the circulating air with clean water (pure water) to achieve a relative humidity of 40 to 65%.

In this way, in the clean booth for silicon polycrystal charging work of the present invention, like the conventional open clean booth for silicon polycrystal charging work shown in FIG. 3, dust generated from the silicon polycrystal 18' is removed from the open clean booth 1'. Since there is no discharge as air (23) discharged outside the device from ), contamination of other devices or jigs installed in the raw material preparation room, quartz crucibles before charging of stored silicon polycrystals, or quartz crucibles with completed filling of silicon polycrystals It becomes possible to suppress.

Example

Hereinafter, the present invention will be described in detail through Examples and Comparative Examples, but the present invention is not limited to these.

(Example)

As shown in FIG. 4(a), in the sealed clean booth of the present invention as shown in FIG. 1 placed in the raw material preparation room 24, polycrystalline silicon is charged into a quartz crucible, and the amount of contamination in the raw material preparation room outside the device is measured. did.

An ionizer was installed as a static electricity removal device in the clean booth, and a primary filter was installed in the exhaust port.

The differential pressure between the sealed clean booth of the present invention and the raw material preparation room was controlled to be 1 Pa when the entrance 20 was closed and -1 Pa when the entrance was opened.

The hole diameter of the quartz crucible used in the filling operation was 800 mm in diameter, and the polycrystal filling amount was 400 kg. For measurement, an airborne particle counter conforming to ISO21501-4 (JIS B 9921) is installed at the measurement point (A1) in the clean booth with a floor (or top) height of 1 m in the center of the clean booth. It was done. In addition, in the raw material preparation room other than the clean booth, measurement was performed at a measurement point (A2) outside the clean booth, 1 m from the entrance 20 of the clean booth and 1 m high from the floor (or top).

Measurements were carried out continuously both in the clean booth and in the raw material preparation room outside the clean booth, and the maximum value of the number of particles (particle size of 0.3 μm or more) within 1 m ³ was compared as the cleanliness level. In addition, measurements were conducted under each condition: normal when charging was not performed, during charging, and when the entrance to the clean booth was open.

(Comparative Example 1)

Using the conventional technology, an open clean booth 1' as shown in FIG. 3, it is placed in the raw material preparation room 24' as shown in FIG. 4(b), and an in-air particle counter is placed in the center of the clean booth, on the floor ( Alternatively, it is installed at the measurement point (B1) in the clean booth with a height of 1 m, and in the raw material preparation room other than the clean booth, it is 1 m from the entrance (20') of the clean booth, on the floor (or top). The test was carried out under the same conditions as in the example, except that it was installed at the measurement point (B2) in a clean booth with a height of 1 m. Meanwhile, each charging operation in Examples and Comparative Examples was performed independently.

Table 1 shows each measurement point in Example and Comparative Example 1 and the maximum value of the number of particles under each condition.

[Table 1]

Table 2 lists the upper concentration limits for ISO cleanliness classes (measured particle size of 0.3 μm or more).

[Table 2]

As can be seen from the measurement point outside the clean booth (A2) and the measurement point outside the clean booth (B2) under normal conditions, the raw material preparation room is ISO cleanliness class 4. In the prior art (Comparative Example 1), more than 100,000 pieces of dust were generated within the open clean booth (1') during work (measuring point (B1) in the clean booth during work), and some of it was discharged into the raw material preparation room outside the device. (Measurement points other than the clean booth during work (B2)). At this time, it was found that the raw material preparation room (24') of Comparative Example 1 was contaminated up to ISO cleanliness class 5 to 6. On the other hand, in the embodiment using the clean booth of the present invention, since a closed clean booth is used, the number of particles in the raw material preparation room other than the device (measuring point (A2) other than the clean booth during work) does not change at all even during work, and after the end of work Even when the entrance was opened, the number of particles outside the device (measuring point (A2) outside the clean booth when the entrance was opened) did not change at all, and it was confirmed that dust inside the sealed clean booth (1) was not discharged outside the device. . In addition, in the present invention, it was confirmed that by installing an ionizer as a static electricity removal device and a primary filter at the exhaust port, dust is not adsorbed to the panel and dust can be efficiently recovered through downflow (clean during work). Difference between the measurement point in the booth (A1) and the measurement point in the clean booth (B1)).

(Comparative Example 2)

Furthermore, although it is the same closed clean booth as the present invention, the clean booth is kept under the same conditions (quartz crucible hole diameter, silicon polycrystalline charge amount, measurement conditions) even in the closed clean booth where the actual pressure inside the clean booth is not controlled when the entrance is opened and closed. The cleanliness of the raw material preparation room other than the clean booth was measured. An in-air particle counter was installed as in the example, the measurement point in the clean booth was C1, and the measurement point outside the clean booth was C2.

Table 3 shows each measurement point in Comparative Example 2 and the maximum value of the number of particles under each condition.

[Table 3]

The maximum value of the number of particles in the clean booth during work at the measurement point (A1) in the clean booth and the measurement point (C1) in the clean booth is almost the same, and as in the above-described embodiment, an ionizer is installed as a static electricity removal device in the exhaust port, etc. By installing, it was confirmed that dust was not adsorbed to the panel and that dust could be recovered more efficiently by downflow compared to the case of using an open clean booth, which is a conventional technology (Comparative Example 1) (clean booth during work) Difference between my measuring point (B1) and my measuring point (C1) in the clean booth).

In Comparative Example 2, when the entrance was opened after work was completed, the actual pressure was not controlled, so dust in the sealed clean booth was discharged outside the device (measurement point (C2) outside the clean booth when the entrance was opened).

Meanwhile, the present invention is not limited to the above embodiments. The above-mentioned embodiment is an example, and anything that has substantially the same structure as the technical idea described in the claims of the present invention and exhibits the same effects is included in the technical scope of the present invention.

Claims (5)

As a clean booth for charging silicon polycrystalline into a quartz crucible,
This clean booth is sealed by the ceiling, sides, and floor,
an entrance arranged on the side,
A fan/filter device disposed on the ceiling surface,
It has an exhaust port disposed at the lower part of the side,
By blowing clean air into the clean booth by the fan and filter device disposed on the ceiling, exhausting the air in the clean booth through the exhaust port, and returning the exhausted air to the fan and filter device, Circulate the air inside the clean booth to form a downflow within the clean booth,
a control mechanism that controls the pressure inside the clean booth when the entrance is opened to be the same pressure or negative pressure with respect to the pressure outside the clean booth;
The control mechanism includes a door switch/sensor for commanding the opening of the entrance,
a control unit that receives a command to open the entrance from the door switch sensor;
an intake damper that adjusts the intake amount of air outside the device into the clean booth;
a blowing damper that adjusts the amount of blowing air from the fan/filter to the inside of the clean booth;
It has a differential pressure sensor that detects a pressure difference between the inside of the clean booth and the outside of the clean booth,
The control unit receives a command to open the entrance from the door switch/sensor, reduces the output of the fan/filter device before opening the entrance, and adjusts the opening degree of the intake damper and the opening degree of the blowing damper. For silicon polycrystalline filling work, characterized in that the pressure inside the clean booth is adjusted by varying the opening degree, and the entrance is opened after checking the pressure difference between the inside of the clean booth and the outside of the clean booth by the differential pressure sensor. 's clean booth. According to paragraph 1,
A clean booth for silicon polycrystalline charging work, wherein the control mechanism controls the pressure difference between the inside of the clean booth and the outside of the clean booth to be -2 to 0 Pa when the entrance is opened. delete According to paragraph 2,
The control mechanism includes a door switch/sensor for commanding the opening of the entrance,
a control unit that receives a command to open the entrance from the door switch/sensor;
an intake damper that adjusts the intake amount of air outside the device into the clean booth;
a blowing damper that adjusts the amount of blowing air from the fan/filter to the inside of the clean booth;
It has a differential pressure sensor that detects a pressure difference between the inside of the clean booth and the outside of the clean booth,
The control unit receives a command to open the entrance from the door switch/sensor, reduces the output of the fan/filter device before opening the entrance, and adjusts the opening degree of the intake damper and the opening degree of the blowing damper. For silicon polycrystalline filling work, characterized in that the pressure inside the clean booth is adjusted by varying the opening degree, and the entrance is opened after checking the pressure difference between the inside of the clean booth and the outside of the clean booth by the differential pressure sensor. 's clean booth. According to any one of paragraphs 1, 2, and 4,
an air conditioning line for blowing in a portion of air outside the device taken in by the air intake damper and air exhausted from the exhaust port;
It has an air conditioning device for a clean room connected to this air conditioning line,
A silicon polycrystal, characterized in that, by this clean room air conditioning device, air outside the device and a part of the exhausted air blown in from the air conditioning line are air conditioned, and this air conditioned air is supplied to the fan and filter device. Clean booth for charging work.