JP6669355B2 - Floating zone melting equipment - Google Patents

Description

  The present invention relates to, for example, an infrared concentrated heating type floating zone melting apparatus that grows a rod-shaped single crystal by irradiating infrared rays to a part of a rod-shaped sample to be heated and melted, and solidifying this on a seed crystal or the like. .

  At the first focal position on the bottom side of the ellipsoidal reflecting mirror, an infrared irradiating means provided with an infrared lamp such as a halogen lamp or a xenon lamp is arranged, and the infrared light emitted from the infrared lamp of the infrared irradiating means is collected. A floating zone melting method is used to collect a solid sample (eg, a rod-shaped sample) placed at this position at a second focal position on the opening side of the ellipsoidal reflecting mirror and locally melt and precipitate the solid sample to form a single crystal. So far, many floating zone melting apparatuses using the floating zone melting method and their application examples have been reported.

  In the floating zone melting method, a sample can be dissolved and deposited without using a container such as a crucible, there is no contamination from a crucible material or the like, and a rod-shaped sample (hereinafter, also referred to as a sample rod) is dissolved and deposited. This is an extremely excellent method capable of growing a single crystal having a homogeneous composition from a rod-shaped sample prepared to have a homogeneous composition.

  On the other hand, the method of growing single crystals that is exclusively used industrially is the pulling method. In this pulling method, a raw material is put into a crucible made of a noble metal such as platinum or iridium and melted, and a seed crystal is immersed in the crucible and pulled up to grow a large single crystal.

However, this pulling method has drawbacks such as that the crucible material is mixed as impurities into the crystal and that the concentration of the added substance is not constant.
Therefore, if a large single crystal can be grown by the above-mentioned floating zone melting method, the floating zone melting method is as follows:
(1) Since no crucible is used, the cost is reduced.
(2) Since there is no contamination from the crucible, a high-purity single crystal product can be produced.
(3) Since a raw material having a homogeneous composition is used, a single crystal having a homogeneous composition can be grown.
Thus, the method is overwhelmingly industrially advantageous.

  Currently, a floating zone melting apparatus using such a floating zone melting method has a single elliptical mirror type floating zone melting apparatus in which one infrared irradiation means is provided beside the sample rod, and the infrared irradiation means is a sample rod. A double elliptical mirror-type floating zone melting device arranged on both sides of the sample, a four elliptical mirror-type floating zone melting device arranged such that infrared irradiation means surrounds the rod-shaped sample from all sides (for example, Patent Document 1), An oblique irradiation type four elliptical mirror type floating zone melting device in which an infrared irradiation means surrounds the rod-shaped sample from all sides and arranges the rod-shaped sample in two stages vertically and irradiates the rod-shaped sample with oblique infrared rays (for example, Patent Document 2) )and so on.

  The floating zone melting device uses a plurality of infrared irradiation means as the irradiation amount of the infrared light increases according to the number of the infrared irradiation means and the diameter of the single crystal to be grown increases. Particularly in recent years, large-diameter single crystals have been actively grown.

  When growing a large-diameter single crystal, the sample rod 110 is heated and melted to solidify the melt on the seed crystal 112 as shown in FIG. 7A, and the crystal is gradually thickened. If the single crystal becomes thicker, the sample rod 110 is irradiated. If the focusing area of the infrared light 102 from the infrared irradiation means 100 is not enlarged, a stable melt cannot be obtained, and the heating position needs to be adjusted. Becomes

  For this reason, it is necessary to move the position of the infrared irradiation means 100 as shown in FIG. 7B together with the growth of the single crystal. For example, the irradiation position of the infrared irradiation means 100 is adjusted by a horizontal position adjusting mechanism (not shown). Has been adjusted. In FIG. 7, reference numeral 100a denotes an ellipsoidal reflecting mirror, reference numeral 100b denotes an infrared lamp, and reference numeral 114 denotes a growing crystal (a growing single crystal).

JP-A-9-235171 Japanese Patent No. 5279727

  Incidentally, the movement of the infrared irradiating means 100 by such a horizontal position adjusting mechanism (not shown) has a structure in which the ellipsoidal reflecting mirror 100a and the infrared lamp 100b are moved together, so that a large-diameter single crystal is grown. In this case, it is necessary to move the infrared irradiation means 100 indicated by the dotted line in FIG. 7B as the infrared irradiation means 100 indicated by the solid line in FIG. 7B.

  When the elliptical reflecting mirror 100a and the infrared lamp 100b are moved together as described above, the size of the floating zone melting apparatus becomes considerably large, and the manufacturing cost increases and the installation location is limited. Had occurred.

  Although the floating zone melting apparatus shown in FIGS. 7A and 7B is a single elliptical mirror type, it is actually a four elliptical mirror type floating zone melting apparatus or an oblique irradiation type four elliptic mirror type floating zone melting apparatus. In the melting device, this horizontal position adjusting mechanism (not shown) is used to grow a large-diameter single crystal. Therefore, in this state, the size of the floating zone melting apparatus increases with the increase in the diameter of the crystal, and measures are required.

  In view of such circumstances, the present invention does not require an excessively large apparatus for growing a large-diameter single crystal, can stably dissolve a sample rod, and can provide a large-diameter single crystal. An object of the present invention is to provide a floating zone melting apparatus capable of reliably growing a crystal.

The present invention has been invented to achieve the object described above,
The floating zone melting device of the present invention,
A sample rod is placed in a sample chamber made of a transparent quartz tube, and an atmospheric gas is flown into the sample chamber. In this state, infrared rays irradiated from infrared irradiation means are condensed on the sample rod and heated and melted. An infrared concentrated heating type floating zone melting apparatus for obtaining a melt of the sample rod, solidifying the melt on a seed crystal and growing a single crystal,
The infrared irradiation means,
An elliptical reflecting mirror that uses the inner surface as a reflecting surface, and an infrared lamp,
Further, the infrared lamp includes:
A lamp moving means is provided which is movable within a predetermined range from a first focal position on the bottom side of the elliptical reflecting mirror.

With this configuration, it is possible to change the size of the focusing area by moving only the infrared lamp without moving the elliptical reflecting mirror.
Since the single crystal grows gradually from a small diameter to a large diameter and grows to a large diameter, it is preferable that the diameter of the infrared light focusing region and the diameter of the single crystal are always substantially the same. In the floating zone melting apparatus of the present invention, by moving only the infrared lamp, it is possible to adjust the size of the light-collecting area gradually according to the growth of the single crystal.
Therefore, a large-diameter sample rod can be stably dissolved without increasing the size of the floating zone melting apparatus, and a large-diameter single crystal can be reliably grown.

  Furthermore, when the infrared lamp is moved to the bottom side of the ellipsoidal reflector, the infrared light emitted from the infrared lamp is reflected to the ellipsoidal reflector in a wider range, so that the inner surface of the ellipsoidal reflector is removed. It can be efficiently used as a reflection surface, and the light collection efficiency can be increased.

Further, the floating zone melting apparatus of the present invention,
In the ellipsoidal reflecting mirror,
A reflecting mirror moving means is provided which is movable within a predetermined range with respect to the infrared lamp.

  If the elliptical reflector can be moved together with the infrared lamp in this way, the size of the focusing area can be freely changed depending on the relative positional relationship between the two, so that a large diameter single crystal can be changed to a small diameter. Single crystals of various sizes up to the crystal of the above can be stably and surely grown.

Further, the floating zone melting device of the present invention,
While forming an operation hole at the bottom of the elliptical reflecting mirror,
Both ends of the infrared lamp in the longitudinal direction are oriented in the major axis direction of the ellipsoidal reflecting mirror, and one end thereof is inserted into the operation hole,
The infrared lamp is configured to be movable in the major axis direction of the ellipsoidal reflecting mirror by the lamp moving means.

  With such a configuration, when the infrared lamp is moved to the bottom side of the ellipsoidal reflecting mirror, the infrared light emitted from the infrared lamp is reflected to the elliptical reflecting mirror over a wider range. The inner surface of the surface reflecting mirror can be efficiently used as a reflecting surface, and the light collection efficiency can be increased.

  Furthermore, by arranging the longitudinal direction of the infrared lamp along the major axis direction of the elliptical reflecting mirror, it is possible to reduce the influence of the electrode becoming a shadow in infrared rays reflected from the elliptical reflecting mirror, As a result, light use efficiency can be improved.

Further, the floating zone melting apparatus of the present invention,
A through hole is formed in a side surface of the ellipsoidal reflector so as to pass through a first focal point on the bottom side of the ellipsoidal reflector in a direction orthogonal to a direction from the bottom of the ellipsoidal reflector toward the opening. ,
Both ends in the longitudinal direction of the infrared lamp are directed in the short axis direction of the elliptical reflecting mirror, and both ends are inserted into the through-hole,
The infrared lamp is configured to be movable in the major axis direction of the ellipsoidal reflecting mirror by the lamp moving means.
Even with such a configuration, a large-diameter single crystal can be stably and reliably grown.

Further, the floating zone melting apparatus of the present invention,
A plurality of the infrared irradiation means are provided.
If a plurality of infrared irradiation means are provided in this manner, the dissolution of a large-diameter sample rod can be performed more stably and reliably than in the case of a single elliptic floating zone melting apparatus, and the growth of a large-diameter single crystal. Can be performed reliably.

  In the case where a plurality of infrared irradiation means are provided, the four-ellipsoidal mirror type floating zone melting device stably grows a single crystal having a larger diameter more stably than the bi-elliptic mirror type floating zone melting device. can do. Furthermore, the oblique irradiation type four elliptic mirror type floating zone melting apparatus can stably and surely grow a single crystal having a larger diameter than the simple four elliptic mirror type floating zone melting apparatus.

Further, the floating zone melting apparatus of the present invention,
A plurality of the infrared irradiation means are installed at equal intervals on the same circumference centered on the sample rod.
With such a configuration, the entire circumference of the sample rod can be substantially uniformly heated and melted.

Further, the floating zone melting device of the present invention,
The elliptical reflection mirror is disposed such that a straight line from the first focal position on the bottom side to the second focal position on the other side is inclined downward by 25 to 35 degrees with respect to the horizontal direction. The infrared light reflected by the mirror is irradiated to the sample rod from obliquely above.
By doing so, the shape of the solid-liquid interface on the crystal side is prevented from becoming convex. Therefore, a single crystal having a large diameter can be grown.

Further, the floating zone melting apparatus of the present invention,
The elliptical reflection mirror is disposed such that a straight line from the first focal position on the bottom side to the second focal position on the other side is inclined upward by 0 to 10 degrees with respect to the horizontal direction. The infrared light reflected by the mirror is irradiated to the sample rod from obliquely below.

  In this way, if the infrared rays irradiating the sample are from both directions of the infrared rays irradiating the sample from diagonally above and the infrared rays irradiating the sample from below diagonally, the infrared rays radiating downward by 25 to 35 degrees The solid-liquid interface of the grown crystal is controlled by irradiation, and the sample can be efficiently and stably dissolved by irradiating infrared rays upward from 0 to 10 so that even a large-diameter sample can be heated and dissolved reliably. By controlling the shape of the solid-liquid interface between the formed large amount of melt and the grown crystal, a single crystal having a large diameter can be stably grown.

Further, the floating zone melting device of the present invention,
The infrared lamp is a halogen lamp or a xenon lamp.
With such an infrared lamp, the sample rod can be stably and reliably dissolved. Since the xenon lamp has a smaller infrared light focusing area than the halogen lamp, the degree of change of the light focusing area obtained when the infrared lamp is moved from the first focal position located on the bottom side of the elliptical reflector is as follows. Larger than halogen lamps.
Therefore, the xenon lamp can more effectively change the size of the light-collecting area.

  According to the present invention, since the infrared lamp is moved by the lamp moving means in accordance with the growth condition of the large-diameter single crystal, the size of the focusing area can be changed, thereby dissolving the sample rod. It can be performed stably, and a single crystal having a large diameter can be reliably grown. Further, it is not necessary to increase the size of the apparatus more than necessary.

  In addition, if the infrared lamp is arranged so that its longitudinal direction is along the major axis of the ellipsoidal reflecting mirror, the influence of the electrode of the infrared lamp as a shadow can be reduced, so that a large-diameter single crystal can be grown. It can be done efficiently.

FIG. 1 is a schematic diagram of a floating zone melting apparatus according to a first embodiment of the present invention. FIG. 2 is an enlarged view of a main part showing a positional relationship between the elliptical reflector and the infrared lamp when the size of the light-converging area is changed in the floating zone melting apparatus according to the first embodiment of the present invention. is there. FIG. 3 is a schematic diagram of a floating zone melting apparatus according to a second embodiment of the present invention. FIG. 4 is an enlarged view of a main part showing a positional relationship between an ellipsoidal reflector and an infrared lamp when the size of a focusing area is changed in the floating zone melting apparatus according to the second embodiment of the present invention. is there. FIG. 5 is a schematic diagram illustrating a use state of the floating zone melting apparatus according to the second embodiment of the present invention. FIG. 6 is an explanatory diagram showing how the reflected light from the elliptical reflector changes when the arrangement of the infrared lamp is changed in the floating zone melting apparatus of the present invention. FIG. 6A is an explanatory view showing a case where an infrared lamp is arranged along a short axis direction with respect to an ellipsoidal reflecting mirror, and FIG. 6B is an illustration showing an infrared lamp arranged along a long axis direction with respect to an elliptical reflecting mirror. FIG. FIG. 7 is an explanatory view for explaining a moving state of the infrared irradiation means in the conventional floating zone melting apparatus. FIG. 7A is an explanatory view showing a state before the infrared irradiation means is moved, and FIG. () Is an explanatory view showing a state in which the infrared irradiation means has been moved.

Hereinafter, an embodiment (embodiment) of the present invention will be described in detail with reference to the drawings.
The floating zone melting apparatus according to the present invention grows a rod-shaped single crystal by irradiating a part of a sample rod with infrared rays to heat and dissolve it, and solidifying it on a seed crystal or the like.

In the present specification, the "seed crystal" refers to the initial form of the single crystal in growing a large-diameter single crystal using a floating zone melting apparatus, and "growing crystal" , A single crystal being grown.
FIG. 1 is a schematic diagram showing a floating zone melting apparatus according to a first embodiment of the present invention.

  In the floating zone melting apparatus 10 of the present embodiment, a sample rod 20 is arranged in a sample chamber 12 made of a transparent quartz tube, and an atmosphere gas 14 is caused to flow into the sample chamber 12. The irradiated infrared rays 48 are condensed on the sample rod 20 and the sample rod 20 is heated and melted to obtain a melt. The melt is solidified on the seed crystal 30 to grow a large-diameter single crystal. Is configured. In FIG. 1, reference numeral 32 denotes a grown crystal.

  The infrared irradiating means 40 includes an ellipsoidal reflecting mirror 42 and an infrared lamp 44, and a hole 45 through which one end in the longitudinal direction of the infrared lamp 44 can be inserted is provided at the bottom 42 a of the elliptical reflecting mirror 42. Have been.

  The infrared lamp 44 is disposed at a position including the first focal position 50 located on the bottom portion 42a side of the elliptical reflector 42 of the infrared irradiation means 40, and one end protruding outward from the elliptical reflector 42 moves the lamp. By being fixed to the lamp fixing portion 66 of the means 60, the elliptical reflecting mirror 42 can be moved in the long axis direction (a direction approaching or moving away from the first focal position 50 to the second focal position 52). It is configured.

  In the infrared irradiation means 40 having such a configuration, the infrared light 48 emitted from the infrared lamp 44 is reflected on the inner surface of the ellipsoidal reflecting mirror 42, and the reflected light is condensed at the second focal position 52, and Is to be heated.

  As the infrared lamp 44, a halogen lamp, a xenon lamp, or the like can be used. However, since the xenon lamp has a smaller focusing area than the halogen lamp, it is obtained when the infrared lamp 44 is moved from the first focal position 50. The degree of change of the focused light area is larger than that of the halogen lamp. Therefore, the xenon lamp can change the size of the light-collecting area more effectively, and the xenon lamp is suitable for further enhancing the effect of the floating zone melting apparatus 10 according to the present invention.

  As the material, shape, manufacturing method, and the like of the elliptical reflecting mirror 42 applied to the infrared irradiation means 40, a conventionally known one described in, for example, JP-A-2007-99602 can be adopted.

  In the infrared irradiating means 40 of the present embodiment, the elliptical reflecting mirror 42 and the infrared lamp 44 are arranged in a state of being inclined obliquely upward with respect to the sample rod 20, whereby the infrared light 48 radiated from the infrared lamp 44 is provided. Is applied to the melting position of the sample rod 20 from obliquely above.

  That is, the elliptical reflecting mirror 42 of the present embodiment is arranged such that the straight line from the first focal position 50 to the second focal position 52 is inclined downward by 25 to 35 degrees with respect to the horizontal direction. Thus, the sample 48 is irradiated with the infrared rays 48 from obliquely above.

  As described above, when the sample rod 20 is heated substantially uniformly from the plurality of infrared irradiation means 40 disposed obliquely above the sample rod 20, the circumferential temperature distribution with respect to the sample rod 20 can be made substantially uniform. As a result, a stable molten state can be ensured.

Further, the infrared lamp 44 and the ellipsoidal reflecting mirror 42 constituting the infrared irradiation means 40 are configured to be movable in a direction approaching or moving away from the second focal position 52.
As described above, in the floating zone melting apparatus 10 of the present embodiment, (1) the longitudinal direction of the infrared lamp 44 is arranged along the long axis direction of the ellipsoidal reflecting mirror 42 (the direction of arrow AA ′ in FIG. 1). (2) the infrared irradiation means 40 is disposed obliquely above the sample rod 20; and (3) the infrared lamp 44 and the ellipsoidal reflecting mirror 42 Being movable along the long axis direction is a particularly characteristic structure.

The lamp moving means 60 is used for growing the single crystal and changing the size of the focusing area of the infrared light 48 formed on the second focal position 52 side.
In the present embodiment, a slider mechanism that can move on a rail (not shown) is employed, and the infrared lamp 44 is moved in a direction indicated by an arrow AA ′ in FIG.

  Further, such a lamp moving means 60 is provided with a fine adjustment means 62, such as a micrometer, capable of gradually expanding and contracting the shaft portion 64 with rotation. It is possible to finely adjust the position of 44 (more precisely, the light emitting point of the infrared lamp 44).

  The amount of movement of the infrared lamp 44 in the major axis direction of the elliptical reflecting mirror 42 may be appropriately set according to the thickness of the single crystal to be grown. For example, a crystal having a diameter of about 10 mm to a crystal having a diameter of about 20 mm is obtained. In this case, it is sufficient that the infrared lamp 44 can be moved by about 2 to 6 mm in the direction of arrow A 'in FIG.

  In the present invention, at least the infrared lamp 44 only needs to be configured to be movable in the major axis direction of the elliptical reflecting mirror 42, but the elliptical reflecting mirror 42 is also similar to the infrared lamp 44. Furthermore, the reflecting mirror moving means 70 can be set to be movable in the same direction. The reflector moving means 70 is provided with a mechanism capable of changing the separation distance from the single crystal in order to grow the single crystal and to change the size of the focusing area of the infrared light 48. In the present embodiment, a slider mechanism that can move on a rail (not shown) is employed, and the ellipsoidal reflecting mirror 42 can be moved in a direction indicated by an arrow BB ′ in FIG.

  As described above, if the elliptical reflecting mirror 42 can be moved together with the infrared lamp 44, the size of the focusing area on the second focal position 52 side can be freely changed depending on the relative positional relationship between the two. As a result, single crystals of various sizes from large-diameter single crystals to small-diameter single crystals can be grown.

  In the floating zone melting apparatus 10 of the present embodiment, when growing the seed crystal 30, as shown in FIG. 1, the light emitting point of the infrared lamp 44 is arranged at the first focal position 50 of the ellipsoidal reflecting mirror 42. The seed crystal 30 and the sample rod 20 are set at the second focal position 52.

  When the sample rod 20 is heated and melted to solidify the melt on the seed crystal 30 and gradually increase the thickness of the crystal, the size of the converging region S is substantially equal to the diameter of the crystal as shown in FIG. Similarly, if only the infrared lamp 44 is gradually moved by the lamp moving means 60 in the direction of the arrow A 'while the elliptical reflecting mirror 42 is fixed, the collection formed on the second focal position 52 side. The range of the light range S ′ can be expanded. By setting the focusing region S 'in this way, a single crystal having a large diameter can be stably grown according to the degree of growth. At this time, the adjustment may be made using the reflecting mirror moving means 70.

  As described above, in the present embodiment, since the infrared lamp 44 can be moved by the lamp moving means 60 in a predetermined range in the major axis direction of the ellipsoidal reflecting mirror 42, an apparatus is necessary even when growing a large-diameter single crystal. It is not necessary to increase the size as described above, and the sample rod 20 can be stably and reliably dissolved, and a large-diameter single crystal can be stably grown according to the degree of growth.

As described above, the first embodiment of the present invention has been described, but the present invention is not limited to the above embodiment.
For example, in the above-described embodiment, an example is shown in which only one infrared irradiation unit 40 including the ellipsoidal reflecting mirror 42 and the infrared lamp 44 is arranged on the side of the sample rod 20. It is preferable that a plurality of the infrared rays irradiating means 40 heat the sample rod 20 in a plurality around the sample rod 20 as in Patent Document 1.

By arranging a plurality of infrared irradiation means 40 in this manner, the temperature distribution in the circumferential direction with respect to the sample rod 20 can be made substantially uniform, so that a stable molten state can be secured.
Further, in the first embodiment shown in FIG. 1, an example is shown in which both ends in the longitudinal direction of the infrared lamp 44 are arranged along the major axis direction of the elliptical reflecting mirror 42. However, both ends in the longitudinal direction of the infrared lamp 44 may be arranged along the minor axis direction of the elliptical reflecting mirror 42.

  Further, in the infrared irradiating means 40 of the present embodiment, the elliptical reflecting mirror 42 and the infrared lamp 44 are disposed in a state of being inclined obliquely upward with respect to the sample rod 20, whereby the infrared 48 radiated from the infrared lamp 44 Is configured to irradiate the molten position of the sample rod 20 obliquely from above. In addition, although not shown, the elliptical reflecting mirror 42 and the infrared lamp 44 Infrared irradiating means 40 arranged in a state of being inclined obliquely downward may be used.

That is, the elliptical reflecting mirror 42 is arranged such that a straight line from the first focal position 50 to the second focal position 52 is inclined downward by 25 to 35 degrees with respect to the horizontal direction. Alternatively, a straight line from the first focal position 50 to the second focal position 52 may be arranged such that the inclination angle θ with respect to the horizontal direction is inclined upward by 0 to 10 degrees. For such an upper and lower arrangement, for example, the technology disclosed in Japanese Patent No. 5279727 by the present applicant can be used.
Of course, the infrared irradiating means 40 provided at the lower stage has the same structure and operation as the infrared irradiating means 40 provided at the upper stage as described above.

  The floating zone melting device 80 shown in FIG. 3 shows a second embodiment of the present invention in which both ends in the longitudinal direction of the infrared lamp 44 are arranged along the short axis direction of the elliptical reflecting mirror 42. The same elements as those in FIG. 1 are denoted by the same reference numerals, and detailed description is omitted.

  On the peripheral side surface of the ellipsoidal reflector 42, a direction perpendicular to the direction from the bottom 42a of the ellipsoidal reflector 42 toward the opening 42b (the short axis direction of the ellipsoidal reflector 42) is provided. The through hole 46 is provided so as to include the first focal position 50 on the 42a side.

  In the floating zone melting device 80 of the present embodiment, both ends in the longitudinal direction of the infrared lamp 44 are inserted into the through holes 46, and the lower ends thereof are fixed to the lamp fixing portions 66 of the lamp moving means 60. The elliptical reflecting mirror 42 is movable in the long axis direction.

  For example, when a crystal having a diameter of about 20 mm is obtained from a crystal having a diameter of about 10 mm, the infrared lamp 44 may be moved by about 1 to 3 mm from the center of the through hole 46. It is preferable that the difference between the maximum diameter T2 in the posture of FIG. 3 and the diameter T1 of the through hole 46 is about 2 to 6 mm.

  Note that the infrared lamp 44 has a rod-like shape such as a xenon lamp, and has a form in which only a central portion is swollen. In this case, as shown in FIGS. 4A and 4B, even if the diameter T1 of the through-hole 46 is slightly larger than the above-described maximum diameter T2 of the infrared lamp 44, the through-hole 46 is not required. As long as the infrared lamp 44 can be inserted into the through hole 46, the infrared lamp 44 can be moved in the through hole 46 with a margin in the left-right direction, and the maximum diameter T2 of the infrared lamp 44 and the through hole The difference between the diameter 46 and the diameter T1 may be appropriately set according to the shape of the infrared lamp 44. FIG. 4A is an explanatory view showing a state in which the infrared lamp 44 is inserted into the through hole 46, and FIG. 4B is a diagram in which the infrared lamp 44 is inserted into the through hole 46 and then moved in the left-right direction. FIG. 4 is an explanatory diagram showing a state in which the camera is in a closed state.

  The point is that the dimensions of the through hole 46 may be determined so that the infrared lamp 44 can be moved within a predetermined range in the through hole 46. If the through hole 46 is too large, the light collection efficiency of the infrared light 48 may decrease. Therefore, it is preferable to regulate the size of the through hole 46 so that the light collection efficiency of the infrared light 48 is not reduced as much as possible.

  Note that, in the present embodiment, at least, only the infrared lamp 44 may be configured to be movable in the major axis direction of the elliptical reflecting mirror 42, but as shown in FIG. The surface reflector 42 can also be made movable by the reflector moving means 70.

  If the elliptical reflecting mirror 42 and the infrared lamp 44 can be moved in the longitudinal direction of the elliptical reflecting mirror 42 as described above, the size of the focusing area can be freely adjusted depending on the relative positional relationship between the two. It is possible to stably and surely grow single crystals of various sizes according to the degree of growth.

  When the seed crystal 30 is actually grown in the floating zone melting apparatus 80 according to the second embodiment of the present invention, first, as shown in FIG. , And the seed crystal 30 and the sample rod 20 are set at the second focal position 52.

  In FIG. 3, when the sample rod 20 is heated and melted to solidify the melt on the seed crystal 30 and gradually increase the thickness of the single crystal, the size of the converging region is substantially equal to the diameter of the single crystal. Thus, the infrared lamp 44 is gradually moved by the lamp moving means 60 in the direction of arrow A '.

  In FIG. 3, if the infrared lamp 44 is gradually moved in the direction of arrow A 'by the lamp moving means 60, the range of the light-collecting area formed on the second focal position 52 side can be expanded. Thereby, a large diameter single crystal can be stably grown according to the degree of growth. At this time, the adjustment may be performed using the reflecting mirror moving means 70.

  As described above, in the floating zone melting device 80 according to the second embodiment of the present invention, both ends of the infrared lamp 44 in the longitudinal direction are arranged in the short axis direction of the elliptical reflecting mirror 42 and the lamp movement is performed. By means 60, a predetermined range can be moved along the long axis direction of the ellipsoidal reflector 42 through the through hole 46 of the ellipsoidal reflector 42, so that an apparatus is necessary even when growing a large-diameter single crystal. There is no need to increase the size as described above, and the sample rod 20 can be stably and reliably dissolved, and a large-diameter single crystal can be stably and surely grown according to the degree of growth.

  Note that, in the second embodiment of the present invention shown in FIG. 3, the infrared irradiation means 40 is configured to irradiate the sample rod 20 from the horizontal direction, but the present invention is not limited to this. As in the case of the first embodiment shown in FIG. 1, the sample rod 20 may be arranged so as to irradiate the sample rod 20 with infrared rays 48 from obliquely above.

  In this case, the elliptical reflecting mirror 42 and the infrared lamp 44 are arranged in a state of being inclined obliquely upward with respect to the sample rod 20, whereby infrared rays 48 emitted from the infrared lamp 44 melt the sample rod 20. It is desirable that the position be irradiated obliquely from above.

Further, in addition to this, an infrared irradiation means 40 in which an elliptical reflecting mirror 42 and an infrared lamp 44 are arranged obliquely downward with respect to the sample rod 20 may be used.
That is, the elliptical reflecting mirror 42 is arranged such that a straight line from the first focal position 50 to the second focal position 52 is inclined downward by 25 to 35 degrees with respect to the horizontal direction. Alternatively, a straight line from the first focal position 50 to the second focal position 52 may be arranged such that the inclination angle θ with respect to the horizontal direction is inclined upward by 0 to 10 degrees.

  Also, in the second embodiment, similarly to the case described in the first embodiment, it is preferable to arrange a plurality of infrared irradiation units 40 around the sample rod 20 as in Patent Document 1. As described above, when the sample rod 20 is heated substantially uniformly from the plurality of infrared irradiation means 40 disposed obliquely above the sample rod 20, the circumferential temperature distribution with respect to the sample rod 20 can be made substantially uniform. As a result, a stable molten state can be ensured.

  As described above, in the present invention, as shown in FIG. 1, in the posture when the infrared lamp 44 is installed, both ends of the infrared lamp 44 in the longitudinal direction are aligned with the major axis direction of the elliptical reflecting mirror 42. In some cases, as shown in FIG. 3, both ends in the longitudinal direction of the infrared lamp 44 are arranged in the short axis direction of the ellipsoidal reflecting mirror 42. When a xenon lamp is used, it is preferable that both ends of the infrared lamp 44 in the longitudinal direction are oriented in the long axis direction of the elliptical reflecting mirror 42 as in the first embodiment shown in FIG. It is.

Hereinafter, the reason will be described.
As shown in FIG. 6A, when both ends of the infrared lamp 44 in the longitudinal direction are arranged toward the major axis of the ellipsoidal reflecting mirror 42, irradiation emitted from the light emitting point P of the infrared lamp 44 is performed. The cathode 44a and the anode 44b of the infrared lamp 44 do not form shadows on the light and are not reflected on the reflecting mirror.

  On the other hand, as shown in FIG. 6B, when both ends of the infrared lamp 44 in the longitudinal direction are arranged in the short axis direction of the elliptical reflecting mirror 42, the cathode 44a and the anode Due to the structure, the portion 44b forms a shadow with respect to the irradiation light emitted from the light emitting point P, so that the portion of the elliptical reflecting mirror 42 having a high internal reflection efficiency cannot be used for light collection.

Therefore, as shown in FIG. 6 (a), when the both ends in the longitudinal direction of the infrared lamp 44 are arranged in the long axis direction of the elliptical reflecting mirror 42, the light use efficiency becomes higher.
For these reasons, the floating zone melting apparatus 10 of the first embodiment shown in FIG. 1 is more preferable than the floating zone melting apparatus 80 of the second embodiment shown in FIG.

  In addition, in each embodiment of the present invention, for example, in FIG. 3, only the case where the infrared lamp 44 is moved in the direction of the arrow AA ′ (the long axis direction of the elliptical reflecting mirror 42) will be described. No particular reference is made to the movement in the direction orthogonal to.

  However, for example, in FIG. 5, if the infrared irradiation means 40 composed of the ellipsoidal reflecting mirror 42 and the infrared lamp 44 is simultaneously moved in the direction shown by the arrow CC ′, the irradiation position on the sample rod 20 on the side is changed. Can be moved up and down.

DESCRIPTION OF SYMBOLS 10 ... Floating zone melting apparatus 12 ... Sample chamber 14 ... Atmospheric gas 20 ... Sample rod 30 ... Seed crystal 32 ... Growing crystal 40 ... Infrared irradiation means 42 ... Ellipse Surface reflecting mirror 42a Bottom 42b Opening 44 Infrared lamp 44a Cathode 44b Anode 45 ... Hole 46 ... Through hole 48 ... Infrared 50 ... First focal position 52 ... Second focal position 60 ... Lamp moving means 62 ... Fine adjustment means 64 ... Shaft part 66 ... Lamp fixing part 70 ... Reflector moving means 80 ... Floating zone melting device 100 ... infrared irradiation means 100a ... elliptical reflecting mirror 100b ... infrared lamp 102 ... infrared 110 ... sample rod 112 ... seed crystal 114 ... growing crystal P ... emission point S ... ..Light focusing area S '

Claims (7)

A sample rod is placed in a sample chamber made of a transparent quartz tube, and an atmospheric gas is flowed into the sample chamber. In this state, infrared rays irradiated from infrared irradiation means are condensed on the sample rod and heated and melted. An infrared concentrated heating type floating zone melting apparatus for obtaining a melt of the sample rod, solidifying the melt on a seed crystal and growing a single crystal,
The infrared irradiation means,
An elliptical reflecting mirror that uses the inner surface as a reflecting surface, and an infrared lamp,
In the infrared lamp,
A lamp moving unit that is movable within a predetermined range from a first focal position on the bottom side of the ellipsoidal reflecting mirror;
In the ellipsoidal reflecting mirror,
A floating zone melting device, comprising: a reflecting mirror moving means which is movable within a predetermined range with respect to the infrared lamp. While forming an operation hole at the bottom of the elliptical reflecting mirror,
Both ends of the infrared lamp in the longitudinal direction are oriented in the major axis direction of the ellipsoidal reflecting mirror, and one end thereof is inserted into the operation hole,
The floating zone melting apparatus according to claim 1, wherein the infrared lamp is configured to be movable in a major axis direction of the ellipsoidal reflecting mirror by the lamp moving unit. A through hole is formed in a side surface of the ellipsoidal reflector so as to pass through a first focal point on the bottom side of the ellipsoidal reflector in a direction orthogonal to a direction from the bottom of the ellipsoidal reflector toward the opening. ,
Both ends in the longitudinal direction of the infrared lamp are directed in the short axis direction of the elliptical reflecting mirror, and both ends are inserted into the through-hole,
The floating zone melting apparatus according to claim 1, wherein the infrared lamp is configured to be movable in a major axis direction of the ellipsoidal reflecting mirror by the lamp moving unit.   The floating zone melting apparatus according to any one of claims 1 to 3, wherein a plurality of the infrared irradiation units are provided.   The floating zone melting apparatus according to claim 4, wherein a plurality of the infrared irradiation means are installed at equal intervals on the same circumference around the sample rod.   The elliptical reflection mirror is disposed such that a straight line from the first focal position on the bottom side to the second focal position on the other side is inclined downward by 25 to 35 degrees with respect to the horizontal direction. The floating zone melting apparatus according to any one of claims 1 to 5, wherein the infrared rays reflected by a mirror are radiated to the sample rod from obliquely above. The floating zone melting apparatus according to any one of claims 1 to 6 , wherein the infrared lamp is a halogen lamp or a xenon lamp.

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