TWI422717B - Clean bench and method of producing raw material for single crystal silicon - Google Patents

Description

Cleaning station and method for manufacturing raw material of single crystal germanium

The present invention relates to a cleaning station for selecting polycrystalline germanium according to size or quality, which is a raw material to be melted when a single crystal crucible is produced, and a method for producing a single crystal germanium raw material, which comprises a cleaning procedure of the polycrystalline germanium.

In general, in the production of polycrystalline germanium as a single crystal germanium raw material, the heated twin seeded rod is exposed to a raw material gas including chlorodecane gas and hydrogen. The polycrystalline lanthanum is deposited into a cylindrical shape by the twin seeding rod, and is crushed into pieces of an appropriate size or cut into rods of a predetermined length to provide a raw material of single crystal ruthenium. The raw material of the polycrystalline germanium and single crystal germanium is packaged and sent to a single crystal crucible manufacturing plant. Prior to packaging, the polysilicon is manually selected based on size or quality. This selection method is, for example, carried out in a cleaning station, as exemplified in the patent application filed in Japanese Patent Application No. 2005-279576. The cleaning station includes a blower that supplies air through a high-performance filter that supplies air to a work space formed on the workbench and an air intake hole that draws air from the work space. The workspace is continuously supplied with clean air through the blower and the suction port so as to maintain a high degree of cleanliness on the table. Therefore, in the selection of polysilicon, this procedure prevents impurities from adhering to the polysilicon and removes particles of the polysilicon itself via blowing of clean air. As a result, the quality of the produced single crystal germanium can be improved.

Incidentally, when the size and quality of the polycrystalline silicon are selected in the cleaning station, if the particles are charged, the particles will adhere to the polycrystalline silicon by static electricity. thus, The particles will not be removed by the clean air. The required removal effect will not be achieved.

Accordingly, an object of the present invention is to provide a cleaning station capable of preventing particles from adhering to polycrystalline silicon to maintain the quality of the produced single crystal germanium, a cleaning station for selecting polycrystalline germanium according to size and quality, and a method for preparing a single crystal germanium raw material.

The present invention uses the following to achieve the above object.

In other words, the cleaning station of the present invention comprises: a work table on which a polysilicon system is placed; and a box portion including a side plate to surround three sides other than the front surface of the work space above the work table, and a top plate covering the work space An upper side, wherein: a supply hole is formed in a top plate of the box-shaped portion, which supplies clean air to an upper surface of the table; and a freezer is provided that frees clean air supplied from the supply holes to the work space And removing static electricity on the workbench; and the suction holes are formed in the side plates of the box-shaped portion, which sucks air from the work space.

According to the cleaning station described above, the cleaning air is supplied through the supply holes on the table surrounded by the three sides other than the front surface, and the air around the upper side of the table is sucked through the suction holes, thereby keeping the upper side of the table clean. Therefore, the polysilicon placed on the stage can be kept at a high purity. As a result, the quality of the single crystal germanium produced from the polycrystalline germanium as a raw material did not deteriorate.

Further, in the cleaning station according to the present invention, the clean air is released by the freezer and is sprayed on the table. The clean air includes positive and negative ions. Thus, when the particles of the polycrystalline silicon are charged, the positive and negative ions of the clean air The child is electrostatically neutralized with the particles. Therefore, the static electricity on the particles is eliminated. The particles, from which they are electrostatically removed, lose their adhesion and thus do not adhere to the polysilicon and are attracted to the suction holes by the flow of the clean air. The particles are then removed from the surface of the processing station. As a result, the particles can be easily eliminated. Therefore, the high quality of the single crystal germanium produced by the polycrystalline silicon as a raw material can be maintained.

Furthermore, clean air containing positive and negative ions can be supplied to the upper side of the table by the freezer to remove static electricity from the particles on the polycrystalline silicon, thereby easily eliminating the particles. As a result, the quality of the single crystal germanium produced by the polycrystalline silicon as a raw material can be improved.

It is also possible that the cleaning station further comprises a communication path connecting the suction holes and the supply holes; a blower supplying the clean air to the work space; and filtering of particles removed from the clean air supplied by the blower The filter and the blower are provided in the communication path.

In this case, the air sucked through the suction hole is purified through the filter and transmitted to the processing station through the supply hole through the supply hole, thereby circulating the air. Therefore, the upper side of the table can be kept quite clean.

It is also possible that the filter comprises: a first filter disposed on an upstream side of the blower for removing particles having a diameter greater than a predetermined size; and a downstream side disposed on the blower for removing the first pass The second filter of the particles of the filter.

Here, if the particles are removed from the upper side of the table along with the air sucked into the suction holes, they directly enter the blower, which may hinder the driving of the blower. In the present invention, in any case, the particle-removing A filter is provided to communicate the communication between the suction port and the blower. Thus, because the particles are completely removed from the airborne filter by the air delivered to the blower, it does not impede the drive of the blower. Furthermore, the air delivered from the blower is guided to the supply hole through the high efficiency filter, and thus the very clean air can be supplied to the upper side of the table.

The method for producing a single crystal germanium raw material of the present invention comprises: depositing a columnar polycrystalline silicon by reaction with a raw material gas including a chlorodecane gas and hydrogen; crushing the columnar polycrystalline silicon into a plurality of polycrystalline tantalum small pieces or cutting the columnar polycrystalline tantalum Forming a rod-shaped polycrystalline crucible having a predetermined length; cleaning the polycrystalline crucible with an acid to remove impurities adhering to the surface thereof; immersing the washed polycrystalline crucible in a pure water bath to remove residual acid from the surface thereof; drying in a desiccator a polycrystalline germanium taken out from the pure water bath; and the polycrystalline germanium is cleaned by removing static electricity from the surface of the dried polycrystalline crucible, wherein in the cleaning process, the polycrystalline germanium is exposed on the work surface of the cleaning station by exposure to the clean air clean.

The method for producing a single crystal germanium raw material according to the present invention comprises: depositing a columnar polycrystalline silicon through reaction with a raw material gas including a chlorodecane gas and hydrogen; crushing the columnar polycrystalline silicon into a plurality of polycrystalline tantalum small pieces or cutting the columnar polycrystalline tantalum Forming a rod-shaped polycrystalline crucible having a predetermined length; cleaning the polycrystalline crucible with an acid to remove impurities adhering to the surface thereof; immersing the washed polycrystalline crucible in a pure water bath to remove residual acid from the surface of the polycrystalline crucible; by placing in a desiccator Drying the polycrystalline germanium removed from the pure water bath; and cleaning the polycrystalline germanium from the surface of the dried polycrystalline germanium, wherein the polycrystalline germanium is exposed to clean air to remove static electricity during the cleaning process, ie by placing the polycrystalline germanium At the same time, the cleaned air is supplied to the polysilicon at the same time and the clean air is discharged to the side of the table.

According to the above method of producing a single crystal germanium raw material, particles can be removed from the surface of the polycrystalline silicon by free clean air. Thereby, the quality of the polycrystalline silicon can be improved to a raw material of single crystal germanium.

Specific examples of the invention will now be described with reference to the drawings.

1 is a front elevational view of a cleaning station unit according to an exemplary embodiment of the present invention, and FIG. 2 is a side cross-sectional view illustrating air flow in the cleaning station unit. The cleaning table unit 30 as shown in Fig. 1 includes two cleaning stations 1 provided side by side, which have constituent parts that are symmetrically provided in each other. Each of the cleaning stations 1 schematically includes a work table 2 on which a work space 3 and a box (box portion) 4 are provided. The case 4 includes a side plate 8a disposed on a side surface of the work table 2 and the work space 3 (on the right side of FIG. 2), and a side plate 8b disposed adjacent to the two cleaning tables 1, and covering the same The top plate 16 on the upper side of the side plates 8a and 8b.

The work table 2 includes a work area 2a that is horizontally provided and has a predetermined height. The operator extends in from the front (the left side of Fig. 2) according to the size and quality to select the polysilicon on the work area 2a. Further, a table communication path 5 is provided to allow the work surface 2a to communicate with the lower side surface 2b of the table 2 close to the side plate 8a of the case 4. The table communication path 5 is opened on a portion of the work surface 2a, and the opening portion is a table suction hole 2c. The table suction hole 2c is covered by the net.

The case 4, as described above, includes side plates 8a and 8b surrounding the table 2 and the side of the work space 3, and a top plate 16 covering the side plates 8a and 8b from the top. The case 4 is formed to be hollow inside. The case 4 extends in the vertical direction by side plates 8a and 8b parallel to the two side faces of the table 2. Further, the case 4, as shown in Fig. 2, includes a vertically extending portion 4a in which a blower 11 (described later) is disposed in an upper inner portion thereof and disposed above the vertically extending portion 4a to pass therethrough The top plate 16 covers the upper extension portion 4b of the work space 3 from the top.

Inside the vertically extending portion 4a of the side plate 8a behind the table 2, as shown in Fig. 2, is a communication path 7 extending up and down. A connecting portion 9 is formed in the lower side surface 2b of the table 2 and the lower portion of the side plate 8a to communicate the communication path 7 with the table communication path 5. Further, the suction hole 10a is formed around the upper side of the table 2 in the side plate 8a of the vertically extending portion 4a, and the working space 3 is communicated with the communication path 7. Further, the suction hole 10b is formed around the upper side of the table 2 in the side plate 8b facing the side of the cleaning table unit 30, and the working space 3 is communicated with the communication path 7.

The hair dryer 11 provided in the upper inner portion of the vertically extending portion 4a is disposed in contact with the partition wall 12 separating the vertically extending portion 4a from the upper extending portion 4b. The blower 11 draws air in the communication path 7 of the vertically extending portion 4a and conveys the air to the upper extension portion 4b. Further, a filter (first filter) 13 for removing particles is provided between the blower 11 in the communication path 7 and the suction holes 10a, 10b (the upstream side of the blower 11). The air sucked through the suction holes 10a, 10b and the table suction hole 2c is sent to the filter through the particle removing filter 13 Hair dryer 11. The particle-removing filter 13 can, for example, remove particles having a diameter of about 10 μm or more.

The upper extension portion 4b and the vertically extending portion 4a are formed as separate bodies via the partition wall 12. A high-efficiency filter (second filter) 15 having a flat plate shape is provided in the extending portion 4b above the partition wall 12 at a predetermined distance from the lower portion of the partition wall 12 (the downstream side of the blower 11). In the present embodiment, the high-efficiency filter 15 is constituted by a HEPA filter which can largely remove particles included in the passing air (having, for example, a diameter range of 0.3 μm or more) to obtain about 100% of cleaning. degree. The air sent to the upper extension portion 4b through the blower 11 passes through the high efficiency filter 15 to become clean air.

A plurality of holes are provided in the top plate 16 of the upper extension to cover the work space 3. The plurality of holes are supply holes 16a for supplying clean air to the work space 3. The air passing through the high efficiency filter 15 is uniformly supplied to the lower portion of the working space 3 at the end through the plurality of supply holes 16a of the top plate 16. A plurality of illuminators 17 (four in this embodiment), such as fluorescent lamps, are provided on the lower side of the top plate 16 (on one side of the working space 3). The illuminator 17 is arranged in a horizontal direction at regular intervals to illuminate the entire working surface 2a of the table 2.

A freezer 20 is provided on the lower side of the top plate 16 (one side of the working space 3) while a plurality of illuminators 17 are disposed. A plurality of nozzles 20a (eight in this specific example) are provided on the freezer 20 and face down. The freezer 20 is used to dissipate a part of the clean air into positive or negative by a corona discharge or the like supplied through the nozzles 20a, and the air is supplied to the working space 3 through the supply hole 16a of the top plate 16. . The free device 20 can be a different type of conventional free In addition to corona discharge, the freezer can free clean air by a variety of different methods, such as using UV rays, light X-rays, and radiant materials.

Hereinafter, a method of preparing a polycrystalline germanium for a single crystal germanium material using the above-described cleaning stage unit 30 will be described.

The method includes depositing a columnar polycrystalline silicon by reaction with a raw material gas including a chlorodecane gas and hydrogen; crushing the columnar polycrystalline silicon into a plurality of polycrystalline tantalum pieces or cutting the columnar polycrystalline silicon into a rod-shaped polycrystalline crucible having a predetermined length; The polycrystalline silicon is washed with an acid to remove impurities adhering to the surface thereof; the washed polycrystalline silicon is immersed in a pure water bath to remove residual acid from the surface thereof; and the polycrystalline germanium taken out from the pure water bath is dried by being placed in a desiccator; The dried polycrystalline germanium surface is cleaned of static electricity to clean the polycrystalline germanium; and the polycrystalline germanium is packaged for transport to a factory that manufactures single crystal germanium.

First, in the crucible deposition process, according to the so-called Siemens process, as shown in Fig. 3, the twin seeding rod 41 disposed in the reactor 40 is heated, for example, by current heating to high temperature. . Next, the material gas is supplied into the reactor 40 through the raw material gas supply pipe 42 to be in contact with the twin seeding rod 41, whereby the polycrystalline silicon R is deposited via a reduction reaction to form a pillar around the twin seeding rod 41. The gas remaining in the reactor 40 is discharged to the outside via the gas discharge pipe 43.

In the crushing process, the columnar polycrystalline silicon R produced in the crucible deposition process is crushed by thermal shock, for example, heating and rapid cooling. Then, the columnar polycrystalline silicon R is tapped by a hammer to be crushed, thereby forming a small block C of the polycrystalline silicon shown in Fig. 4.

In the cutting process, the columnar polycrystalline crucible R is cut into a predetermined length using a diamond cutter to form a rod-shaped polycrystalline crucible C.

In the cleaning procedure, a rod-shaped polycrystalline crucible is cleaned using a cleaning solution including nitric acid and hydrofluoric acid to remove impurities adhering to the surface thereof. In the impregnation procedure, the polysilicon that has been completely cleaned is immersed in a pure water bath to remove the remaining acid.

In the drying procedure, the already impregnated polycrystalline germanium is placed in a vacuum desiccator to remove moisture from its surface.

In the cleaning procedure, the polysilicon is contacted with the free clean air to remove particles from the surface of the polysilicon using the cleaning station unit 30 described above. First, the polysilicon is placed on the table 2 of the cleaning station 1. Next, when the cleaned air is supplied from the table 2, air is taken from the side of the table 2 and then discharged. Therefore, the surface of the polysilicon and the stage 2 is exposed to clean air to remove static electricity, so the particles are discharged together with the air flow.

The cleaning procedure is described below in the small block C of polycrystalline germanium. As shown in Fig. 5, a polyethylene sheet 52 is laid on the polyethylene dish 51, and a plurality of polycrystalline crumbs C are placed on the sheet 52. The dish 51 is placed on the table 2 of the cleaning station 1 and free clean air is supplied from above the cleaning table 1. In this case, the size or appearance of the individual polycrystalline crumbs C is checked and selected and placed in the polyethylene package 53.

In the cleaning table 1 of the cleaning table unit 30 according to the present specific example, the hair dryer 11 supplies the cleaning air to the work space 3 via the high efficiency filter 15. The air sucked through the suction holes 10a, 10b provided to the lower portion of the working space 3 and the suction opening 2c of the table passes through the table. The path 5 and the communication path 7 are transmitted to the blower 11 to perform air circulation. Thereby, the air supplied to the work space 3 has a cleanliness of about 100% due to the high efficiency filter 15 disposed before the work space 3, and thus the work space 3 can be kept very clean. Therefore, the selected polycrystalline germanium is always in a clean environment so as not to be mixed with impurities to maintain high purity. Therefore, it is possible to prevent deterioration of the quality of the single crystal crucible produced by using polycrystalline germanium as a raw material.

In this embodiment, the clean air supplied through the supply hole 16a is partially dissipated by the freezer 20 disposed on the lower side of the top plate 16 (one side of the working space 3). The clean air includes positive and negative ions, and thereby the static electricity is neutralized if the particles are charged to neutralize the positive and negative ions by the electrostatic properties of the polycrystalline silicon particles. Particles that are removed by static electricity will lose adhesion. Therefore, the particles do not adhere to the polysilicon and are sucked by the clean air to the suction holes 10a, 10b or the table suction holes 2c. As a result, the particles are removed from the surface of the table 2 and the working space 3. As described above, since the static electricity is removed from the particles, the particles can be easily eliminated from the stage 2. Therefore, the single crystal germanium produced from the polycrystalline silicon as a raw material can maintain its high quality.

If the polycrystalline silicon particles are removed from the surface of the table 2 and the working space 3 together with the air sucked into the suction holes 10a, 10b or the table suction holes 2c, directly enter the hair dryer 11. The blower 11 may not be properly driven. In this specific example, the filter 13 for removing particles is provided between the suction holes 10a, 10b of the communication path 7 and the blower 11 in any case. Thereby, the particles can be self-filtered by the particles The air delivered to the blower 11 is completely removed. As a result, the hair dryer 11 can be appropriately driven without trouble, and the air can be repeatedly circulated.

In the packaging process, the polycrystalline crucible is thereby purified and packaged in a polyethylene bag that is transferred to a factory that manufactures single crystal crucibles. This polycrystalline germanium is supplied as a raw material of single crystal germanium. As described above, the polycrystalline silicon surface has been purified in the cleaning station by the cleaning procedure, and thereby high quality single crystal germanium can be produced.

Although the cleaning station unit 30 using the cleaning station 1 according to an embodiment of the present invention has been described above, the present invention is not limited thereto. It is apparent to those skilled in the art that various modifications and changes can be made within the scope of the invention.

Although the specific examples have been exemplified in connection with cleaning the small pieces of polycrystalline silicon, the polycrystalline silicon as the raw material of the single crystal germanium according to the present invention can optionally crush the columnar polycrystalline silicon into small pieces of polycrystalline silicon or cut into rod-shaped polycrystalline silicon having a predetermined length. And prepared. Regarding the rod-shaped polysilicon, in the cleaning procedure, for example, the rods may be placed one by one on the sheet 52 to check the appearance while being exposed to the clean air, and then placed one by one in the package.

Although specific examples of the invention have been described and illustrated in the foregoing, it should be understood that these are exemplary of the invention and are not considered as limiting. Additions, deletions, substitutions, and other modifications may be made without departing from the spirit or scope of the invention. Therefore, the invention is not to be considered as limited by the foregoing description, and is only limited by the scope of the appended claims.

1‧‧‧cleaning station

2‧‧‧Workbench

2a‧‧‧Workspace

2b‧‧‧lower surface

2c‧‧‧Worktop suction hole

3‧‧‧Workspace

4‧‧‧ box

4a‧‧‧ Vertical extension

4b‧‧‧Upper extension

5‧‧‧Workbench connectivity

7‧‧‧Connected pathways

8a‧‧‧ side panels

8b‧‧‧ side panels

9‧‧‧Connected section

10a‧‧‧ suction holes

10b‧‧‧ suction holes

11‧‧‧Blowers

12‧‧‧ next door

13‧‧‧ Filters to remove particles

15‧‧‧High efficiency filter

16‧‧‧ top board

16a‧‧‧Supply hole

17‧‧‧ illuminators

20‧‧‧ Freezer

20a‧‧‧Nozzles

30‧‧‧ cleaning station unit

40‧‧‧Reactor

41‧‧‧矽晶棒

42‧‧‧Material gas supply pipe

43‧‧‧ gas discharge pipe

51‧‧‧polyethylene dish

52‧‧‧Polyethylene sheet

53‧‧‧Polyethylene bags

R‧‧‧ Polysilicon

C‧‧‧polycrystalline small pieces

Fig. 1 is a schematic configuration of a cleaning station according to a specific example of the present invention.

Fig. 2 is a side sectional view showing the flow of air in the cleaning table unit according to an exemplary embodiment of the present invention.

Fig. 3 is a schematic cross-sectional view showing a reactor for a deposition process when a single crystal germanium raw material is produced.

Fig. 4 is a front view showing a rod-shaped polycrystalline crucible taken out from the reactor by being crushed into small pieces.

Fig. 5 is a view showing an example of cleaning a polycrystalline crucible on the stage of the cleaning station of Fig. 1.

1‧‧‧cleaning station

2‧‧‧Workbench

2a‧‧‧Workspace

2b‧‧‧lower surface

2c‧‧‧Worktop suction hole

3‧‧‧Workspace

4‧‧‧ box

4a‧‧‧ Vertical extension

4b‧‧‧Upper extension

5‧‧‧Workbench connectivity

7‧‧‧Connected pathways

8a‧‧‧ side panels

8b‧‧‧ side panels

9‧‧‧Connected section

10a‧‧‧ suction holes

10b‧‧‧ suction holes

11‧‧‧Blowers

12‧‧‧ next door

13‧‧‧ Filters to remove particles

15‧‧‧High efficiency filter

16‧‧‧ top board

16a‧‧‧Supply hole

17‧‧‧ illuminators

20‧‧‧ Freezer

20a‧‧‧Nozzles

30‧‧‧ cleaning station unit

Claims (4)

A cleaning station comprising: a work table on which a polysilicon system is placed; a box-shaped portion including a side plate to surround three sides other than a front surface of the work space above the work table; and a top plate covering the upper side of the work space, wherein a supply hole formed in a top plate of the box-shaped portion, which supplies clean air to an upper surface of the work table; and a freezer that dissipates clean air supplied to the work space from the supply holes and removes the work The static electricity on the stage; and the suction holes are formed in the side plates of the box-shaped portion, which draws air from the working space. The cleaning station of claim 1, further comprising: a communication path connecting the suction holes and the supply holes; a hair dryer supplying the clean air to the working space; and the hair dryer The supplied clean air removes the filter of the particles, wherein the filter and the blower are provided in the communication pathway. The cleaning station of claim 2, wherein the filter comprises: a first filter disposed on an upstream side of the hair dryer for removing particles having a diameter larger than a predetermined size; and being disposed on the hair dryer The downstream side is for removing the second filter of particles passing through the first filter. A method of producing a single crystal germanium raw material, comprising: Depositing a columnar polycrystalline silicon through reaction with a raw material gas including chlorodecane gas and hydrogen; crushing the columnar polycrystalline silicon into a plurality of polycrystalline tantalum pieces or cutting the columnar polycrystalline silicon into rod-shaped polycrystalline silicon having a predetermined length; cleaning with acid The polysilicon is removed to remove impurities adhering to the surface thereof; the washed polysilicon is immersed in a pure water bath to remove residual acid from the surface thereof; the polycrystalline germanium taken out from the pure water bath is dried by being placed in a desiccator; The surface of the dried polycrystalline silicon is cleaned to remove the static electricity, wherein the polycrystalline germanium is exposed to the cleaning on the stage of the cleaning station according to any one of claims 1 to 3 in the cleaning procedure. The air is cleaned.