JP4006967B2 - Single crystal production equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a single crystal production facility by the CZ method, and more particularly to a single crystal production facility in which a plurality of pulling furnaces equipped with horizontally opposed magnets are installed and arranged in a pulling chamber.
[0002]
[Prior art]
High-purity silicon single crystals are often used for semiconductor element substrates for integrated circuits, and the Czochralski method, abbreviated as CZ method, is usually used for the production of silicon single crystals.
[0003]
In the production of a silicon single crystal by the CZ method, a pulling furnace 10 as shown in FIG. 1 is used. The pulling furnace 10 shown here includes a large-diameter main chamber 11 as a furnace body, and a small-diameter pull chamber 12 overlaid thereon. A crucible 13 is disposed in the center of the main chamber 11. The crucible 13 has a double structure in which an inner quartz crucible 13a and an outer support crucible 13b made of graphite are combined, and is supported on a support shaft 14 called a pedestal via a crucible receiver 15. The support shaft 14 is driven in the axial direction and the circumferential direction, whereby the crucible 13 is moved up and down and rotated.
[0004]
An annular heater 16 is disposed outside the crucible 13, and a heat insulating material (not shown) is disposed along the inner surface of the main chamber 11. On the other hand, a cylindrical heat shield 17 surrounding the silicon single crystal 21 pulled from the raw material melt 20 in the crucible 13 is installed above the crucible 13. The heat shield 17 has a reverse cone part whose diameter gradually decreases downward, and the reverse cone part cuts off radiant heat from the heater 16 and the raw material melt 20 to promote cooling of the silicon single crystal 21. To do.
[0005]
In operation, the furnace body is adjusted to a predetermined atmosphere, and the raw material melt 20 is formed in the crucible 13. The seed crystal 22 attached to the lower end of the pulling shaft suspended in the main chamber 11 through the pull chamber 12 is immersed in the raw material melt 20, and the pulling shaft is raised while rotating the crucible and the pulling shaft from this state. The silicon single crystal 21 is grown below the seed crystal 22 and pulled into the pull chamber 12.
[0006]
Such a pulling furnace 10 is usually arranged in plural in the pulling chamber so as to face the work space. An example of the arrangement is shown in FIG. The opposite side of the work space across the pulling furnace 10 is a maintenance space.
[0007]
On the other hand, each pulling furnace 10 may be equipped with a horizontal horizontal magnet according to the required crystal quality and productivity. A pulling furnace equipped with a horizontal horizontal magnet is shown in FIG. A pair of electromagnets 30, 30 are installed across the main chamber 11 of the pulling furnace 10. The electromagnets 30 and 30 have a function of suppressing convection of the raw material melt 20 by forming a horizontal magnetic flux line and applying it to the raw material melt 20 in the crucible 13. In FIG. 3, 18 is a gate valve, and 19 is a lifting / lowering / rotating mechanism of a pulling shaft.
[0008]
By causing the magnetic flux lines in the horizontal direction to act on the raw material melt 20 in the crucible 13, the oxygen concentration uniformity (ROG) in the wafer surface and the specific resistance uniformity in the wafer surface (which are problems in a large diameter wafer of 300 mm) ( A reduction in RRG) is avoided. Further, in the pulling of 300 mm crystal, high-speed growth is one of the problems, but horizontal magnetic field application is an effective measure for this high speed. For this reason, in the pulling up of the 300 mm crystal, which has recently been mass-produced, it is becoming essential to apply a magnetic field using a horizontal horizontal magnet.
[0009]
[Problems to be solved by the invention]
However, in a pulling furnace equipped with a horizontal horizontal magnet, a leakage magnetic field becomes a problem. FIG. 4 is a plan view showing the intensity distribution of the leakage magnetic field from a pulling furnace equipped with a horizontal horizontal magnet showing 4000 gauss in the center of the furnace, which is a general magnet capacity. As can be seen from FIG. 4, the leakage magnetic field strength exceeds 100 gauss even at a position 2 m away from the furnace.
[0010]
With respect to this leakage magnetic field, measures for suppressing the leakage magnetic field are described in, for example, Japanese Patent Laid-Open No. 8-333190 from the viewpoint of lowering the magnetic efficiency. However, measures to suppress the leakage magnetic field lead to an increase in the size and cost of the equipment. In addition, the leakage magnetic field not only causes a decrease in magnetic efficiency, but also adversely affects the magnetic field distribution in the furnace due to the interference of the leakage magnetic field between adjacent pulling furnaces, as well as safety for workers. May cause problems. Safety issues for workers include the adverse effects of magnetic fields on the human body and the occurrence of mechanical accidents due to the magnetic material being attracted to the pulling furnace.
[0011]
If the leakage magnetic field is weakened, these problems can be solved. However, as described above, the countermeasures increase the size and cost of the equipment.
[0012]
An object of the present invention is to provide a single crystal production facility that can avoid magnetic field interference and safety problems between adjacent pulling furnaces without weakening the leakage magnetic field from the pulling furnace.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the single crystal production facility of the present invention has a plurality of pulling furnaces equipped with horizontal horizontal magnets installed in the pulling chamber facing the work space, and faces the work spaces of the respective pulling furnaces. , Each pulling furnace is equipped with the magnet so that the direction of the magnetic flux line is inclined more than 0 degree and less than 90 degrees, preferably 30 to 60 degrees in the horizontal plane with respect to the front face. Preferably, the directions of the magnetic flux lines in the plurality of pulling furnaces arranged in one or two directions are substantially the same.
[0014]
In the single crystal production facility of the present invention, the magnetic flux line direction in a plurality of pulling furnaces arranged in the pulling chamber is inclined in a horizontal plane with respect to the front surface, so that a leakage magnetic field is generated in both the front-rear direction and the lateral direction of the pulling furnace. The spread of is suppressed. As a result, interference of the leakage magnetic field between adjacent pulling furnaces can be avoided. Moreover, the leakage magnetic field strength in the work space can be reduced, and the safety of the worker can be ensured.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 5 is a layout diagram of a single crystal manufacturing facility showing an embodiment of the present invention.
[0016]
The single crystal manufacturing facility of the present embodiment includes a plurality of pulling furnaces 10, 10... Arranged in a pulling chamber. The plurality of pulling furnaces 10, 10,... Are arranged in two rows on both sides of the work space. That is, they are arranged in two vertical rows and several horizontal rows across the work space. Each pulling furnace 10 is equipped with the horizontal horizontal magnets 30, 30 shown in FIG. 3, and the designed front to be directed to the work space is directly directed to the work space, and the horizontal horizontal magnets 30, 30 are formed. The direction of the magnetic flux lines is inclined 45 degrees horizontally from the front in all furnaces. That is, the horizontal horizontal magnets 30 and 30 are attached to the furnace body so that the direction of the magnetic flux lines in each furnace is inclined 45 degrees horizontally from the front, and the directions of the magnetic flux lines are parallel in all the furnaces. .
[0017]
The structure of the pulling furnace 10 itself is as described with reference to FIG.
[0018]
6 and 7 are layout diagrams of a single crystal manufacturing facility showing a comparative example. In Comparative Example 1 shown in FIG. 6, horizontal horizontal magnets 30 and 30 are attached to the furnace body so that the direction of the magnetic flux lines passes through the front in all furnaces. That is, the inclination angle from the front in the direction of the magnetic flux line is 0 degree in all the furnaces. Moreover, in the comparative example 2 shown in FIG. 7, the horizontal horizontal magnets 30 and 30 are attached to the furnace body so that the inclination angle from the front in the direction of the magnetic flux line is 90 degrees in all furnaces.
[0019]
In the following, the function of the single crystal manufacturing facility of the present embodiment shown in FIG. 5 will be described in comparison with Comparative Examples 1 and 2 shown in FIGS.
[0020]
In Comparative Example 1 shown in FIG. 6, since the tilt angle from the front in the direction of the magnetic flux lines is 0 degrees in all the pulling furnaces 10, 10,..., The magnetic flux lines spread back and forth in each furnace. For this reason, the leakage magnetic field strength in the work space is increased, and the worker is exposed to a strong magnetic field. On the other hand, the lateral spread of the magnetic flux lines is reduced. For this reason, it is easy to avoid interference of leakage magnetic fields between the pulling furnaces 10 and 10 adjacent in the lateral direction. As a result, the pulling furnaces 10, 10,.
[0021]
In Comparative Example 2 shown in FIG. 7, since the tilt angle from the front in the direction of the magnetic flux line is set to 90 degrees in all the pulling furnaces 10, 10,... The risk of exposure to a strong magnetic field is reduced, but the lateral spread of the magnetic flux lines is increased, and due to the interference of the leakage magnetic field between the adjacent adjacent lifting furnaces 10, 10, the lifting furnace 10, It is necessary to separate 10 ·· in the lateral direction. As a result, a large installation space (lifting room) is required.
[0022]
On the other hand, in the single crystal manufacturing facility of the present embodiment shown in FIG. 5, the inclination angle from the front in the direction of the magnetic flux lines is set to 45 degrees in all the pulling furnaces 10, 10,. For this reason, both the spread in the front-rear direction and the lateral spread of the leakage magnetic field are suppressed to be small. Specifically, the leakage magnetic field at the equal position in the front-rear direction is reduced to 1 / 1.33 compared to Comparative Example 1, and the leakage magnetic field at the equal position in the horizontal direction is 1/1. Reduce to 33. For this reason, the risk of the operator being exposed to a strong magnetic field in the work space is reduced, and it becomes easy to avoid interference of leakage magnetic fields between the pulling furnaces 10 and 10 adjacent in the lateral direction. .. can be approached laterally.
[0023]
As described above, in the single crystal manufacturing facility of the present embodiment, the direction of the magnetic flux lines in the plurality of pulling furnaces 10, 10... Arranged in the pulling chamber is inclined 45 degrees in the horizontal plane with respect to the front surface. The spread of the leakage magnetic field is suppressed in both the front-rear direction and the lateral direction. As a result, interference of the leakage magnetic field between the adjacent pulling furnaces 10 and 10 can be avoided, and the interval can be reduced. Moreover, the leakage magnetic field strength in the work space can be reduced, and the safety of the worker can be ensured.
[0024]
In the above embodiment, the angle of inclination from the front in the direction of the magnetic flux lines in the plurality of pulling furnaces 10, 10... Arranged in the pulling chamber is 45 degrees, but within a range of 30 to 60 degrees. For example, it is possible to obtain substantially the same effect as in the case of 45 degrees, and when suppressing the spread of the magnetic flux lines in the lateral direction, it is preferable to approach 30 degrees, and when spreading the magnetic flux lines in the front-rear direction is further suppressed. Is preferably close to 60 degrees.
[0025]
【The invention's effect】
As described above, the single crystal production facility of the present invention does not weaken the leakage magnetic field from the pulling furnace by inclining the direction of the magnetic flux lines in the plurality of pulling furnaces arranged in the pulling chamber from the front in the horizontal plane. In both cases, magnetic field interference and safety problems between adjacent pulling furnaces can be avoided. Therefore, a measure for weakening the leakage magnetic field from the pulling furnace can be omitted, which is very advantageous in terms of equipment scale and equipment cost.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing the structure of a pulling furnace.
FIG. 2 is a layout diagram illustrating an arrangement example of a pulling furnace.
FIG. 3 is an elevational view showing the structure of a pulling furnace equipped with a horizontal horizontal magnet.
FIG. 4 is a plan view showing an intensity distribution of a leakage magnetic field from a pulling furnace equipped with a horizontal horizontal magnet.
FIG. 5 is a layout diagram of a single crystal manufacturing facility showing an embodiment of the present invention.
6 is a layout diagram of a single crystal production facility of Comparative Example 1. FIG.
7 is a layout diagram of a single crystal production facility of Comparative Example 2. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Pulling furnace 11 Main chamber 12 Pull chamber 13 Crucible 14 Support shaft 15 Crucible receptacle 16 Heater 17 Thermal shield 20 Raw material melt 21 Silicon single crystal 22 Seed crystal 30 Horizontal horizontal magnet

Claims (3)

A plurality of pulling furnaces equipped with horizontal horizontal magnets are installed facing the work space in the pulling chamber. The surface facing the work space of each pulling furnace is the front, and the inclination angle of the magnetic flux lines with respect to the front is a horizontal plane. to Do so that 30 to 60 degrees at the inner, single crystal manufacturing equipment, characterized in that the magnets each pulling furnace is equipped. The single crystal manufacturing facility according to claim 1, wherein a plurality of pulling furnaces are arranged in one direction or two directions, and directions of magnetic flux lines in these pulling furnaces are substantially the same. A plurality of pulling furnaces equipped with horizontal horizontal magnets are installed facing the work space in the pulling chamber, and the plurality of pulling furnaces are arranged in one or two directions, and the magnetic flux in these pulling furnaces Each pulling direction is almost the same, and the surface facing the working space of each pulling furnace is the front, and the magnetic flux line direction is inclined more than 0 degree and less than 90 degrees in the horizontal plane with respect to the front. A single crystal manufacturing facility, characterized in that a furnace is equipped with the magnet.

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