JP2019156694A - Clean booth for silicon polycrystal filling work - Google Patents

Abstract

To provide a clean booth in which an environment is not contaminated by dust generated in a process for filling polycrystal in a raw material vessel, when silicon single crystal is produced.SOLUTION: A clean booth for filling polycrystal in a quarts crucible includes: a gateway which is sealed by a ceiling face, a side face and a floor face, and which is arranged at the side face; a fan filter device arranged at the ceiling face; an air outlet port arranged at a bottom part of the side face; and a control mechanism for controlling pressure inside the clean booth when opening the air outlet port by sending clean air into the clean booth by the fan filter device, discharging air in the clean booth from the air outlet port, and returning it to the fan filter device, so as to become the same pressure or a negative pressure in relation to pressure outside of the clean booth.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a clean booth used in a step of filling a raw material container with silicon polycrystal used as a molten raw material when producing a silicon single crystal by an ingot, particularly a CZ method.

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

  Since the silicon polycrystal in the quartz crucible needs to be filled in a clean state, it is generally a room (hereinafter referred to as a raw material) separate from the space where the single crystal pulling apparatus is installed (the pulling chamber). The quartz crucible is filled in the preparation room. Due to the recent increase in diameter of silicon single crystals and miniaturization of semiconductor elements, it is necessary to use a large-diameter quartz crucible and perform the silicon polycrystal filling process in the quartz crucible in an environment that is not further contaminated with dust. It is said that.

  In Patent Document 1, which is a prior art, the incorporation work is performed in a clean booth or a clean bench to prevent particle contamination inside and outside the pulling apparatus, and the raw material container is conveyed in a state where the upper opening of the raw material container is closed with a lid. Although it is disclosed to prevent contamination of the raw material in the container and particle contamination of the pulling chamber generated from the raw material, during the assembly work (state before closing the lid on the upper opening of the raw material container) Dust generated from the raw material contaminates the clean booth or clean bench, and is discharged when the clean booth door is opened or closed to transport the air discharged from the clean booth or clean bench opening or the raw material container. The air around the clean booth or the raw material preparation room is contaminated.

  For example, FIG. 3 is a cross-sectional view showing an example of a conventional clean booth for an open type silicon polycrystal filling operation. Conventionally, the raw material preparation chamber is generally set to be higher in cleanliness than the pulling chamber such as ISO cleanliness class 4 or class5, and the filling operation of the silicon polycrystal 18 ′ into the quartz crucible 17 ′ is performed by the raw material preparation. It is carried out in a clean bench installed in the room or in an open type clean booth 1 '.

  The silicon polycrystal 18 ′ is stored in a clean plastic bag, for example, but is opened to fill the quartz crucible 17 ′ and filled in the quartz crucible 17 ′. The open type clean booth 1 ′ has a side face of the clean booth 1 ′ covered with, for example, a vinyl sheet 22, and external air 13 ′ (clean air in the raw material preparation chamber) is supplied by a fan filter device 3 ′ (FFU). In order to suck and supply clean air 11 ′ into the apparatus, the inside of the apparatus is pressurized from the raw material preparation chamber. Pressurized air in the apparatus is discharged as air 23 discharged outside the apparatus from an opening provided in a lower part such as a vinyl sheet 22 that covers the side surface of the clean booth 1 ′. For example, when opening the plastic bag and filling the silicon crucible 17 ′ with the silicon polycrystal 18 ′, dust generated from the silicon polycrystal 18 ′ is discharged out of the open clean booth 1 ′. Other devices and jigs that are exhausted together with the air 23 to be prepared and installed in the raw material preparation chamber, or quartz crucibles that have been stored before filling the silicon polycrystalline, or quartz crucibles that have been filled with the silicon polycrystalline The problem of polluting has occurred. In particular, in recent years when semiconductor elements have been miniaturized, the effects of contamination of the quartz crucible and jig have become obvious. For example, a quartz crucible and a clean booth for storing jigs need to be installed as countermeasures against the contamination. It has been said.

JP 7-172975 A

  The present invention has been made in view of the above-described problems. When a silicon single crystal is manufactured by a CZ method (Czochralski method) or the like, a silicon polycrystal used as a melting material is filled in a material container. An object is to provide a clean booth that does not pollute the surroundings with dust generated in the process.

  In order to solve the above problems, the present invention is a clean booth for filling a silicon crucible into a quartz crucible, the clean booth being sealed by a ceiling surface, a side surface, and a floor surface. Clean air by the fan filter device disposed on the ceiling surface, having a doorway disposed, a fan filter device disposed on the ceiling surface, and an exhaust port disposed at a lower portion of the side surface. Air inside the clean booth, exhausting the air in the clean booth from the exhaust port, returning the exhausted air to the fan filter device, circulating the air inside the clean booth, and The pressure inside the clean booth when the down flow is formed in the booth and the entrance is opened, with respect to the pressure outside the clean booth, Providing clean booth for polycrystalline silicon filling operation, characterized in that those having a control mechanism for controlling such that the pressure or negative pressure.

  If it is a clean booth for such silicon polycrystal filling work, in the silicon polycrystal filling work into the quartz crucible, for example, when opening the plastic bag and filling the silicon polycrystal into the quartz crucible, It is possible to provide a sealed clean booth in which dust generated from silicon polycrystal is not discharged outside the booth, and to suppress contamination of the raw material preparation chamber.

  At this time, it is preferable that 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 opening the entrance.

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

  In addition, the control mechanism includes a door switch sensor for instructing opening / closing of the entrance / exit, a control unit receiving an instruction to open the entrance / exit from the door switch / sensor, and air outside the apparatus to the clean booth An intake damper that adjusts the intake air amount, an air damper that adjusts the air flow amount from the fan filter into the clean booth, and a differential pressure that detects a pressure difference between the clean booth interior and the clean booth exterior The controller receives a command to open the door from the door switch sensor, and reduces the output of the fan filter device before opening the door to reduce the intake damper. The pressure inside the clean booth is adjusted by varying the opening of the blower and the opening of the blower damper, and the differential pressure sensor After confirming the difference in pressure between the serial clean booth interior and the clean booth outside, it is preferable that for opening the doorway.

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

  And an air conditioning line for taking in part of the outside air sucked by the intake damper and a part of the air exhausted from the exhaust port, and a clean room air conditioner connected to the air conditioning line, A clean room air conditioner air-conditions a part of the outside air and the exhausted air taken in from the air conditioning line, and supplies the air-conditioned air to the fan filter device. Is preferred.

  If it is such a clean booth for filling silicon polycrystals, it becomes possible to suppress the deterioration of the working environment due to internal lighting of the sealed clean booth and heat generated by the worker.

  If it is the clean booth for silicon polycrystal filling work of the present invention, in silicon polycrystal filling work, for example, when opening a plastic bag and filling the silicon polycrystal into a quartz crucible, It is possible to provide a sealed clean booth in which generated dust is not discharged out of the apparatus and to suppress contamination of the raw material preparation chamber. Therefore, the filling process of the silicon polycrystal in the quartz crucible can be performed in an environment that is not further contaminated with dust or the like.

It is sectional drawing which shows the example of the clean booth for the sealing type silicon polycrystal filling operation | work of this invention. It is a perspective view which shows the example of the clean booth for the sealing type silicon polycrystal filling operation | work of this invention. It is sectional drawing which shows the example of the clean booth for the conventional open type silicon polycrystal filling operation | work. It is the top view (a) which shows the raw material preparation chamber in which the clean booth in the Example was installed, and the top view (b) which shows the raw material preparation chamber in which the clean booth in the comparative example 1 was installed.

  As described above, in conventional clean booths for filling silicon polycrystals, clean booths or cleans are caused by dust generated from raw materials during assembly work (the state before the lid is closed at the upper opening of the raw material container). Around the clean booth or raw material preparation room due to exhaust air that is contaminated and exhausted from the opening of the clean booth or clean bench, or air that is released when opening and closing the clean booth entrance to transport raw material containers There was a problem that would be contaminated.

  And, as a result of intensive studies to solve the above problems, the inventors of the present invention have a sealed type in which dust generated from the silicon polycrystal is not discharged outside the booth when the silicon polycrystal is filled in the raw material container. If you have a control mechanism that controls the pressure inside the clean booth to be the same or negative with respect to the pressure outside the clean booth when opening the entrance of the clean booth The present inventors have found that it is possible to suppress contamination around the clean booth or the raw material preparation chamber.

  That is, the apparatus of the present invention is a clean booth for filling a silicon crucible into a quartz crucible, and the clean booth is hermetically sealed by a ceiling surface, a side surface, and a floor surface, and an inlet / outlet disposed on the side surface. And a fan / filter device disposed on the ceiling surface and an exhaust port disposed at a lower portion of the side surface, and clean air is supplied to the clean booth by the fan / filter device disposed on the ceiling surface. The air inside the clean booth is exhausted, the air inside the clean booth is exhausted from the exhaust port, and the exhausted air is returned to the fan filter device, thereby circulating the air inside the clean booth and down to the clean booth. The pressure inside the clean booth when the flow is formed and the entrance is opened is the same or negative with respect to the pressure outside the clean booth. And it has a control mechanism for controlling so.

  Hereinafter, although this invention is demonstrated concretely, this invention is not limited to this.

  First, the clean booth for filling silicon polycrystal according to the present invention will be described. FIG. 1 is a cross-sectional view showing an example of a clean booth for sealing silicon polycrystal according to the present invention. FIG. 2 is a perspective view showing an example of a clean booth for sealing silicon polycrystal filling work according to the present invention. A clean booth for filling silicon polycrystal is disposed in a clean raw material preparation chamber.

  As described above, as shown in FIGS. 1 and 2, the closed clean booth 1 has the side surface and the ceiling surface completely sealed with the panel and the floor surface, and the entrance / exit 20 is provided on the side surface. The panel is kept highly airtight with a clean room high heat insulation panel and clean room sealant in order to increase air conditioning efficiency, and the entrance / exit 20 is provided with a resin belt drive and a dustproof cover on the movable part and is an automatic door considering dust generation prevention. It is desirable. Further, an exhaust port 4 is provided on a side surface other than the side surface provided with the entrance / exit 20 within a height of 300 mm from the floor surface, and the air 10 exhausted by the fan filter device 3 (FFU) connected by the circulation line 14 is circulated. Then, clean air 11 is supplied into the clean booth to form a downflow (laminar flow). Further, in order to suppress the deterioration of the working environment due to the internal lighting of the closed clean booth 1 and the heat generated by the worker 21, a part of the exhausted air 10 is branched to the air conditioning line 15, and the clean room air conditioner 2 It is also possible to supply air to the fan / filter device 3 in harmony with air. Further, the outside air 13 (clean air in the raw material preparation chamber) that is fresh air is taken in for the worker, and the inside of the closed clean booth 1 is not pressurized too much from the raw material preparation chamber outside the booth. Clean exhaust air 12 is discharged. The outside air 13 and the clean exhaust air 12 are adjusted by the differential pressure sensor 7 for detecting the pressure difference between the inside of the clean booth 1 and the outside of the clean booth 1 to adjust the opening degree of the intake damper 8 and the blower damper 9, When 20 is closed, it is controlled at about −2 to +2 Pa. The clean exhaust air 12 directly discharges the clean air that has passed through the fan / filter device 3 from a predetermined height that is not affected by dust generation. There is no contamination.

  The entrance / exit 20 is used when the quartz crucible 17, the silicon polycrystal 18, and other filling jigs are carried into the sealed clean booth 1 in order to fill the quartz crucible 17 with the silicon polycrystal 18, or quartz Opened when carrying out the filling of the silicon polycrystal 18 into the crucible 17. 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 the control mechanism 25, the opening / closing port 20 is transmitted to the control unit 19 by the door switch / sensor 6. The control unit 19 immediately reduces the motor output of the fan filter device 3 to reduce the circulating air flow and at the same time adjusts the exhaust amount of the clean exhaust air 12 and the air supply amount of the outside air 13. The opening of the intake damper 8 to be adjusted is varied, and the differential pressure detected by the differential pressure sensor 7 is -2 to 0 Pa, that is, the inside of the closed clean booth 1 is the same pressure as the raw material preparation chamber or the raw material preparation Reduce the pressure slightly from the room. After confirming that the differential pressure sensor 7 shows −2 to 0 Pa of the above condition, the control unit 19 opens the entrance / exit 20 to enable the quartz crucible 17 and the silicon polycrystal 18 to be carried in and out. As described above, by setting the pressure difference between the sealed clean booth 1 and the raw material preparation chamber to −2 to 0 Pa, for example, opening of a plastic bag and silicon polycrystal 18 in the sealed clean booth 1 are performed. When the quartz crucible 17 is filled, dust from the silicon polycrystal 18 is not discharged out of the apparatus, and other apparatuses and jigs installed in the raw material preparation chamber, or the stored silicon Contamination to the quartz crucible before the filling of the crystal 18 and the quartz crucible that has been filled with the silicon polycrystal 18 can be prevented.

  Further, in the sealed clean booth 1 of the present invention, by providing the static eliminator 16, it is difficult for the dust to be adsorbed to the panel, and the side surface other than the side surface provided with the entrance / exit 20 is exhausted within a height of 300 mm from the floor surface. Dust can be efficiently removed by forming the down flow (laminar flow) by providing the opening 4, circulating the air 10 exhausted by the fan filter device 3, and supplying clean air 11. In addition to easily collecting dust by installing a removable primary filter 5 at the exhaust port 4, the life of the filter of the fan / filter device 3 can be extended. For example, an ionizer can be installed in the static eliminator 16, but the generation of static electricity can be suppressed by humidifying the circulating air with clean water (pure water) to a relative humidity of 40 to 65%.

  As described above, the clean booth for filling silicon polycrystal according to the present invention is generated from the silicon polycrystal 18 'as in the conventional open booth for filling silicon polycrystal shown in FIG. The discharged dust is not discharged from the open clean booth 1 ′ as air 23 to be discharged outside the apparatus, so other apparatuses and jigs installed in the raw material preparation chamber, or stored silicon polycrystal It is possible to suppress contamination of the quartz crucible before filling and the quartz crucible that has been filled with silicon polycrystal.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated concretely, this invention is not restrict | limited to these.

(Example)
As shown in FIG. 4A, the quartz crucible is filled in the quartz crucible in the sealed clean booth of the present invention as shown in FIG. The amount of contamination in a raw material preparation room was measured.
The clean booth was equipped with an ionizer as a static eliminator and a primary filter at the exhaust port.
The differential pressure between the inside of the closed clean booth of the present invention and the raw material preparation chamber was controlled so that the differential pressure when the entrance / exit 20 was closed was 1 Pa, and the differential pressure when the entrance / exit was opened was −1 Pa.

  The quartz crucible used in the filling operation had a diameter of 800 mm and a polycrystalline filling amount of 400 kg. The measurement was performed by installing an air particle counter conforming to ISO 21501-4 (JIS B 9921) at a measurement point A1 in the clean booth in the center of the clean booth and a floor height of 1 m. Further, in the raw material preparation room outside the clean booth, the measurement was performed by installing it at a measurement point A2 outside the clean booth 1 m from the entrance 20 of the clean booth and 1 m from the floor.

Measurements were continuously made both in the clean booth and in the raw material preparation room outside the clean booth, and the maximum values of the number of particles (particle size of 0.3 μm or more) in 1 m ³ were compared as cleanliness. The measurement was performed under normal conditions when the filling operation was not performed, during the filling operation, and when the clean booth door was opened.

(Comparative Example 1)
A conventional clean booth 1 ′ as shown in FIG. 3 is used, and is placed in the raw material preparation chamber 24 ′ as shown in FIG. 4B. The air particle counter is located in the center of the clean booth, on the floor. Installed at a measurement point B1 in a clean booth with a surface height of 1 m, except for a raw material preparation room outside the clean booth at a measurement point B2 outside the clean booth at 1 m from the clean booth entrance 20 'and 1 m from the floor. Were carried out under the same conditions as in the examples. In addition, each filling operation | work in an Example and a comparative example was performed independently.

  Table 1 shows the respective measurement points in Example and Comparative Example 1, and the maximum number of particles under each condition.

  Table 2 shows the upper limit concentration of the ISO cleanliness class (measured particle size of 0.3 μm or more).

  As can be seen from the measurement point A2 outside the clean booth and the measurement point B2 outside the clean booth, the raw material preparation room is ISO cleanliness class 4. In the prior art (Comparative Example 1), 100,000 or more dusts are generated in the clean booth 1 ′ that is open during the work (measurement point B1 in the clean booth during the work), and part of the raw material is prepared outside the apparatus. It was discharged into the room (measurement point B2 outside the clean booth during work). At this time, it was found that the raw material preparation chamber 24 'of Comparative Example 1 was contaminated to ISO cleanliness class 5-6. On the other hand, in the embodiment using the clean booth of the present invention, since the closed type clean booth is used, the number of particles in the raw material preparation chamber outside the apparatus (measurement point A2 outside the clean booth during the work) does not change at all even during the work. Even when the door is opened after the work is completed, the number of particles outside the device (measurement point A2 outside the clean booth when the door is open) does not change at all, and the dust in the sealed clean booth 1 is not discharged outside the device. I was able to prove that. In the present invention, it was also confirmed that by installing an ionizer as a static eliminator and a primary filter at the exhaust port, the dust is not adsorbed to the panel and can be efficiently collected by downflow (during operation). Difference between measurement point A1 in the clean booth and measurement point B1 in the clean booth).

(Comparative Example 2)
Furthermore, it is a sealed clean booth similar to the present invention, but the same conditions (quartz crucible aperture, silicon polycrystal filling amount, measurement conditions) even in a sealed clean booth that does not control the chamber pressure in the clean booth when opening and closing the entrance / exit The cleanliness of the raw material preparation room inside and outside the clean booth was measured. The air particle counter was installed in the same manner as in the example, and the measurement point inside 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 number of particles under each condition.

  The maximum number of particles in the clean booth during the operation of the clean booth measuring point A1 and the clean booth measuring point C1 is almost the same, and as in the previous embodiment, an ionizer is used as the static eliminator and the primary at the exhaust port. By installing a filter, etc., dust is not adsorbed on the panel, and dust can be collected more efficiently by downflow compared to the case of using an open clean booth that is a conventional technology (Comparative Example 1). (The difference between the measurement point B1 in the clean booth during the operation and the measurement point C1 in the clean booth).

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

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

1, 1 '... Clean booth, 2 ... Clean room air conditioner,
3, 3 '... fan filter device, 4 ... exhaust port, 5 ... primary filter,
6 ... Door switch sensor, 7 ... Differential pressure sensor, 8 ... Intake damper,
9 ... Blower damper, 10 ... Exhausted air, 11, 11 '... Clean air,
12 ... Clean exhaust air, 13, 13 '... Outside air, 14 ... Circulation line,
15 ... Air conditioning line, 16 ... Static eliminator, 17, 17 '... Quartz crucible,
18, 18 '... polycrystalline silicon, 19 ... control unit, 20,20' ... entrance / exit,
21 ... Worker, 22 ... Vinyl sheet, 23 ... Air exhausted outside the device,
24, 24 '... Raw material preparation room, 25 ... Control mechanism,
A1, B1… Measurement points in the clean booth,
A2, B2: Measurement points outside the clean booth.

Claims (4)

A clean booth for filling a silicon crucible into a quartz crucible,
The clean booth is sealed by the ceiling surface, side surface, and floor surface,
An entrance and exit located on the side surface;
A fan filter device disposed on the ceiling surface;
An exhaust port disposed at a lower portion of the side surface,
The fan / filter device arranged on the ceiling surface blows clean air into the clean booth, exhausts the air in the clean booth from the exhaust port, and discharges the exhausted air to the fan / filter device. By returning, the air inside the clean booth is circulated, and a down flow is formed in the clean booth,
It has a control mechanism for controlling the pressure inside the clean booth when opening the entrance to the same or negative pressure with respect to the pressure outside the clean booth. Clean booth for crystal filling work.   2. The control mechanism according to claim 1, 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 doorway is opened. Clean booth for filling silicon polycrystal. The control mechanism includes a door switch sensor for instructing opening of the doorway,
A control unit that receives a command to open the doorway from the door switch sensor;
An intake damper that adjusts the intake air amount outside the apparatus to the clean booth;
A blower damper that adjusts the amount of blown air from the fan filter into the clean booth;
A differential pressure sensor for detecting 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 inlet / outlet from the door switch / sensor, and lowers the output of the fan / filter device before opening the inlet / outlet, thereby opening the intake damper and the air flow. By adjusting the opening of the damper, the pressure inside the clean booth is adjusted, and after confirming the pressure difference between the inside of the clean booth and the outside of the clean booth by the differential pressure sensor, the entrance is opened. 3. The clean booth for filling silicon polycrystal according to claim 1 or 2, wherein the clean booth is provided. An air conditioning line for taking in part of the outside air sucked by the intake damper and the air exhausted from the exhaust port;
A clean room air conditioner connected to the air conditioning line;
By the clean room air conditioner, the outside air taken in from the air conditioning line and a part of the exhausted air are air conditioned, and the air conditioned air is supplied to the fan filter device. The clean booth for filling a silicon polycrystal according to any one of claims 1 to 3, wherein:

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