JP2013159524A - Single crystal growing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a single crystal growing apparatus capable of reducing energy loss of light (heating source) and efficiently melting a sample.SOLUTION: A single crystal growing apparatus includes a pair of reflection mirrors 1 and 2 each provided with a pair of focuses F0 and F1, F0 and F2 and arranged such that the one focus F0 matches, and heating sources 3 and 4 arranged at the other focuses F1 and F2 of the reflection mirrors 1 and 2, and grows a single crystal by irradiating a sample S arranged at one focus F0 of the reflection mirrors 1 and 2 with radiation heat of the heating sources 3 and 4 directly or through reflection by the reflection mirrors 1 and 2. The respective reflection mirrors 1 and 2 comprise a first ellipsoidal mirror 21, a second ellipsoidal mirror 22 disposed on the outer diameter side of the first ellipsoidal mirror 21, and a spherical mirror 23 disposed between the first ellipsoidal mirror 21 and the second ellipsoidal mirror 22.

Description

  The present invention relates to a single crystal growing apparatus.

  In the case of growing a single crystal, it is conventionally known to use a floating zone type single crystal growing apparatus (Patent Document 1 and Patent Document 2). As shown in FIGS. 5 and 6, such a single crystal growing apparatus 50 has two symmetrical elliptical mirrors 51 and 52, and the respective ones of the focal points F0 and F0 (see FIG. 6) coincide with each other. Thus, the heating furnace is configured by opposing coupling. The inner surfaces of the spheroid mirrors 51 and 52, that is, the reflection surfaces are subjected to gold plating in order to reflect infrared rays with high reflectivity. Near the other focal points F1 and F2 of the spheroid mirrors 51 and 52, heating sources, for example, infrared lamps 53 and 54 such as halogen lamps are fixedly arranged. A heated portion 55 is located at the coincident focal point F0 of each spheroid mirror 51, 52, and a raw material rod 57 fixed to the lower end of the upper crystal drive shaft 56 extending in the vertical direction from above, and extending in the vertical direction from below. A seed crystal rod 59 fixed to the upper end of the lower crystal drive shaft 58 is abutted. The upper crystal drive shaft 56 and the lower crystal drive shaft 58 are hermetically held by holding members 60 and 61 as shown in the figure, can be rotated by a drive motor such as a servo motor (not shown), and have a synchronous or relative speed. It is held up and down freely.

  A space m1 in which the raw material rod 57 and the seed crystal rod 59 are disposed is partitioned from a space m2 in which the infrared lamps 53 and 54 are disposed, and a transparent quartz tube 63 that forms a single crystal growth chamber 62 is provided. The single crystal growth chamber 62 is filled with an inert gas suitable for crystal growth.

  According to the single crystal growing apparatus 50, infrared rays emitted from the infrared lamps 53 and 54 arranged at the first and second focal points F 1 and F 2 of the spheroid mirrors 51 and 52 are converted into the spheroid mirror 51. , 52, and condensed by the heated portion 55 located at the common focal point F 0 and heated by infrared rays. By making the lower end of the raw material rod 57 and the upper end of the seed crystal rod 59 of the heated portion 55 to be heated and melted smoothly by the radiant energy by the infrared heating, as shown in FIG. A melt zone 64 is formed in the heated portion 55 between the crystal rods 59.

  Then, the upper crystal drive shaft 56 with the raw material rod 57 fixed at the lower end and the lower crystal drive shaft 58 with the seed crystal rod 59 fixed at the upper end are rotated together, and slowly moved downward with synchronization or relative speed. As a result, the melting zone 64 between the raw material rod 57 and the seed crystal rod 59 is gradually moved toward the raw material rod 57, and the crystal grows to grow a single crystal. In FIG. 7, 57a indicates a solid-liquid interface on the raw material rod 57 side, and 59a indicates a solid-liquid interface on the seed crystal rod 59 side.

  However, the spheroid mirrors 51 and 52 in the single crystal growth apparatus 50 shown in FIGS. 5 and 6 and the like are arranged so as to share the focal points of each other, and thus cannot have a shape of a full ellipse. For this reason, the light deviating from the ellipse is not reflected at the focal point where the raw material rod 57 and the seed crystal rod 59 are disposed, but is merely reflected within the spheroid mirrors 51 and 52.

  For example, the light (radiant heat) that directly reaches and is reflected by the other spheroid mirror 52 (or 51) side where the one infrared lamp 53 (or 54) is not disposed is reflected on the sample (the raw material rod 57 and the seed). It is rarely used for melting the crystal rod 59), and it cannot be said that it is heated efficiently because it becomes energy for heating other than a sample such as a spheroid mirror as well as a portion where melting is not desired. This is because the distance between the heating source and the sample melting portion, that is, the distance between the focal points of the spheroid mirrors is short, so that it cannot be used for melting a reflection region of about half of the ellipse.

  Therefore, a metal reflector that can be efficiently focused as described in Patent Document 3 is used as the spheroid mirror of such a single crystal growing apparatus, or a reflective reflector that has high reflection efficiency as described in Patent Document 4 is used. It can be proposed to use a spotlight such as that described in Patent Document 4 or a spotlight that does not cause color unevenness in the spotlight.

  The metal reflecting mirror described in Patent Document 3 has two spheroid surfaces, and the reflecting reflector described in Patent Document 4 has an elliptical reflecting surface and an arcuate portion. The described spotlight has three elliptical reflectors.

Japanese Examined Patent Publication No. 63-62873 JP-A-2005-247668 US Pat. No. 5,677,983 JP-A-9-166815 JP 2010-274707 A

  In Patent Document 3, Patent Document 4, and Patent Document 5, there is no disclosure or suggestion that these reflecting mirrors are used in a single crystal growing apparatus. That is, even if the reflecting mirror itself reflects efficiently, there is no single crystal growing apparatus that can reduce the incidence of radiant heat from one reflecting mirror on the other reflecting mirror.

  For this reason, even if what is described in Patent Document 3 and Patent Document 4 is simply applied to a single crystal growth apparatus, it cannot be set so that the energy loss of light (heating source) can be reduced.

  Therefore, in view of such circumstances, the present invention provides a single crystal growth apparatus that can reduce the energy loss of light (heating source) and efficiently melt the sample.

  The single crystal growth apparatus of the present invention comprises a pair of reflecting mirrors each having a pair of focal points and arranged so that one focal point coincides, and a heating source arranged at the other focal point of the reflecting mirrors, In the single crystal growing apparatus for directly and directly reflecting the radiant heat of the heating source with a reflecting mirror and irradiating a sample disposed at one focal point of the reflecting mirror to grow a single crystal, each reflecting mirror has a first An ellipsoidal mirror, a second ellipsoidal mirror disposed on the outer diameter side of the first ellipsoidal mirror, and a spherical mirror disposed between the first ellipsoidal mirror and the second ellipsoidal mirror. , The focal point of the first ellipsoidal mirror and the focal point of the second ellipsoidal mirror are the same, this focal point is the focal point of this reflecting mirror, the center of the spherical mirror coincides with the focal point where the heating source is disposed, The spherical mirror and the second ellipsoidal mirror are continuous, and a step is formed between the first ellipsoidal mirror and the spherical mirror. The minimum gap dimension between the surrounding tube and the first ellipsoidal mirror surrounding the sample to be, is obtained by 8.0% to 120% of the outside diameter of the surrounding tube.

  According to the single crystal growing apparatus of the present invention, the minimum gap dimension between the surrounding tube and the first ellipsoidal mirror is set to 8.0% to 120% of the outer diameter of the surrounding tube, so that one reflection The incidence of the radiant heat from the mirror heating source on the other reflecting mirror is reduced, and the energy loss of the radiant heat from the heating source for melting the sample can be reduced.

  In the first ellipsoidal mirror, when the major axis is a1 and the minor axis is b1, b1 / a1 is preferably 0.4 to 0.95. In the first ellipsoidal mirror, when the major axis is a1, the minor axis is b1, and in the second ellipsoidal mirror, the major axis is a2, and the minor axis is b2, a1 / a2 Can be set to 0.5 to 1.0, and b1 / b2 can be set to 0.3 to 0.80. Furthermore, it can be set so that the second ellipsoidal mirror and the spherical mirror are connected to each other on an extended line of a straight line connecting one focal point and the edge on the stepped portion side of the first ellipsoidal mirror.

  In the single crystal growing apparatus of the present invention, the energy loss of radiant heat from the heating source for melting the sample can be reduced, and the sample can be efficiently melted. For this reason, it is possible to grow a single crystal by stably melting in a short time with a heating source having a small capacity.

  b1 / a1 is set to 0.4 to 0.95, a1 / a2 is set to 0.5 to 1.0, b1 / b2 is set to 0.3 to 0.80, one focal point and the first ellipse A single crystal growth apparatus that can reduce the energy loss of radiant heat by setting the second ellipsoidal mirror and the spherical mirror to be connected on the extended line of the straight line connecting the edge of the stepped portion of the surface mirror. Can be provided stably.

It is a simplified sectional view of the single crystal growth device of the present invention. FIG. 2 is a simplified side view of the single crystal growth apparatus of FIG. 1. It is a simplified cross-sectional top view for calculating the energy loss of the single crystal growth apparatus of the said FIG. FIG. 2 is a simplified cross-sectional side view for calculating energy loss of the single crystal growth apparatus of FIG. 1. It is a simplified sectional view of a conventional single crystal growing apparatus. It is AA sectional view taken on the line of FIG. It is an enlarged view of the to-be-heated part in the single-crystal growth apparatus of the said FIG. It is a simplified cross-sectional top view for calculating the energy loss of the conventional single crystal growing apparatus. It is a simplified cross-sectional side view for calculating the energy loss of the conventional single crystal growth apparatus which omitted the deposit adsorption jacket.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  FIG. 1 and FIG. 2 show a single crystal growing apparatus according to the present invention, which has a pair of focal points F0, F1, F0, and F2, and is arranged so that one focal point F0 coincides. A pair of reflecting mirrors 1 and 2 and heating sources 3 and 4 disposed at the other focal points F1 and F2 of the reflecting mirrors 1 and 2 are provided. The reflecting surface constituted by the inner surfaces of the reflecting mirrors 1 and 2 is subjected to a gold plating process or the like for reflecting with high reflectance by infrared rays.

  In the vicinity of the other focal points F1 and F2 of the reflecting mirrors 1 and 2, infrared lamps 3A and 4A such as halogen lamps, for example, are fixedly arranged as an example constituting the heating sources 3 and 4. A sample S (which is an abutting portion between a raw material rod 7 and a seed crystal rod 9 to be described later) located in the heated portion 5 is located at one coincident focal point F0 of each of the reflecting mirrors 1 and 2, and this sample As shown in FIG. 5, a surrounding tube 10 made of a quartz tube is installed in the vertical direction.

  In this surrounding tube 10, the inner portion m1 of the surrounding tube 10 is divided from the inner portions m2 of the other reflecting mirrors 1 and 2 by dividing the inner portion m1 of the surrounding tube 10 into an atmosphere suitable for single crystal growth. It replaces and makes it easy to maintain the atmospheric state. On the other hand, it serves to cool the heating sources 3 and 4 of the inner part m2 in each of the reflecting mirrors 1 and 2 without affecting the heated part 5 in the inner part m1 of the surrounding tube 10.

  In the heated part 5 positioned at the coincident focal point F0 of each of the reflecting mirrors 1 and 2, the raw material rod 7 fixed to the lower end of the upper crystal driving shaft 6 extending in the vertical direction from above, and the lower crystal driving extending in the vertical direction from below. A seed crystal rod 9 fixed to the upper end of the shaft 8 is abutted. The upper crystal drive shaft 6 and the lower crystal drive shaft 8 are hermetically held by a holding member (not shown), are rotatable by a driving motor such as a servo motor (not shown), and are synchronous or have a relative speed. It is held up and down freely.

  In the single crystal growing apparatus, a cylindrical evaporative material adsorption jacket 14 is disposed around the raw material rod 7 in the surrounding tube 10. The evaporative material adsorption jacket 14 is formed in a substantially double cylindrical shape by stainless steel (for example, SUS 304) having high corrosion resistance, and has a cooling medium passage 16 in which a cooling medium circulates. By evaporating the cooling medium, the evaporating substance adsorption jacket 14 is efficiently cooled to enhance the evaporating substance adsorption effect. In the illustrated embodiment, the evaporative material adsorption jacket is disposed only around the raw material rod 7, but may also be disposed around the seed crystal rod 9.

  By the way, each reflecting mirror 1, 2 includes a first ellipsoidal mirror 21, a second ellipsoidal mirror 22 disposed on the outer diameter side of the first ellipsoidal mirror, a first ellipsoidal mirror 21, and a second ellipse. It is formed with a spherical mirror 23 disposed between the surface mirror 22. Therefore, each of the reflecting mirrors 1 and 2 is composed of a plurality (four in this embodiment) of block bodies 25, 26, 27, and 28. That is, the block bodies 25 and 26 constitute the first ellipsoidal mirror 21, the block body 28 constitutes the second ellipsoidal mirror 22, and the block body 27 constitutes the spherical mirror 23.

  The block bodies 25 and 26 are short cylinders, the inner diameter surface of the block body 25 constitutes one focal point F0 side with respect to the shorter diameter of the first ellipsoidal mirror 21, and the inner diameter surface of the block body 26 is the first elliptical surface. The other focal point F1 (F2) side of the minor axis of the mirror 21 is formed. In this case, in the block body 25, the end portion on the one focal point F0 side of the major axis of the first ellipse forming the first ellipsoidal mirror 21 is omitted. In the block body 26, the first ellipse is omitted. The end part on the other focal point F1 (F2) side of the first elliptical major axis forming the surface mirror 21 is omitted.

  The block body 28 is configured by a disk-shaped body in which an arc surface on the end side of the long diameter of the second ellipse forming the second ellipsoidal mirror 22 is formed. Further, the block body 27 is configured by a disk-shaped body whose inner surface forms a spherical surface that forms the spherical mirror 23.

  The reflecting mirrors 1 and 2 can be formed by combining the four block bodies 25, 26, 27, and 28. For this reason, the block body 25 is provided with a flange portion 25a at the other focal point F1 side end, and both ends of the block body 26 are provided with flange portions 26a and 26b, respectively. A collar portion 27b is provided at an end portion that faces (faces) the collar portion 26a of 26.

  The flange portion 25a of the block body 25 and the flange portion 26b of the block body 26 are overlapped, and these are fixed by the bolt member 30, and the flange portion 26a of the block body 26 and the flange portion 27b of the block body 27 are overlapped. These are fixed by the bolt member 30. In this case, a through hole 31 is provided in the flange portion 25a of the block body 25, a screw hole 32 is provided in the flange portion 26b of the block body 26, and a through hole 31 is provided in the flange portion 25b of the block body 27. A screw hole 32 is provided in the flange portion 26 a of the block body 26.

  In addition, the end surface 38 and the inner end surface 39 of the block body 28 are overlapped with each other on the side of the ridge portion of the block body 27, and these are fixed by the bolt member 33. In this case, a through hole 34 is provided in the block body 28, and a screw hole 35 is provided in the end surface 38 of the block body 27.

  For this reason, the focal points F0, F1 (F0, F2) of the first ellipsoidal mirror 21 and the focal points F0, F1 (F0, F2) of the second ellipsoidal mirror 22 are common, and the focal points F0, F1, F2 are the same. This reflecting mirror is focused and coincides with a focal point F1 (F2) where the heating source is arranged at the center O of the spherical mirror 23. Further, the spherical mirror 23 and the second ellipsoidal mirror 22 are continuous, and a step portion 40 is formed between the first ellipsoidal mirror 21 and the spherical mirror 23. Then, the minimum clearance dimension between the surrounding tube 10 surrounding the sample S (the raw material rod 7 and the seed crystal rod 9) disposed at one focal point and the first ellipsoidal mirror 21 is defined as the outer diameter of the surrounding tube 10. 8.0% to 120%, more preferably 8.3% to 116.7%. That is, as shown in FIG. 3, when the minimum gap dimension is t and the outer diameter dimension of the surrounding tube 10 is D, t / D is 0.08 to 1.2.

  In this case, in the first ellipsoidal mirror 21, when the major axis is a1 and the minor axis is b1, b1 / a1 is 0.4 to 0.95, more preferably 0.4 to 0.92. In the second ellipsoidal mirror 22, when the major axis is a2 and the minor axis is b2, b2 / a2 is 0.4 to 0.95, more preferably 0.4 to 0.92. To do. Further, b1 / b2 is set to 0.3 to 0.80, more preferably 0.3 to 0.73. Furthermore, when a1 / a2 is 0.5 to 1.0, more preferably 0.54 to 1.0, and the radius of the spherical mirror 23 is r, r = a1 / 2.

  As shown in FIG. 1, a continuous portion of a second elliptical mirror 22 and a spherical mirror 23 on an extended line of a straight line L connecting one focal point F <b> 0 and an edge 41 on the stepped portion 40 side of the first elliptical mirror 21. There are 42.

  By setting in this way, the incidence of the radiant heat from the heating source 3 (4) of one reflecting mirror 1 (2) to the other reflecting mirror 2 (1) is reduced, and heating for melting the sample is performed. Energy loss of radiant heat from the source 3 (4) can be reduced.

  That is, in FIG. 3, the incident range from the heating source 3 of the one reflecting mirror 1 to the other reflecting mirror 2 (1) is a range indicated by hatching. When the incident range in this case is θ, the energy loss can be calculated at 2θ / 360 °. For example, if θ is 10.294 °, the energy loss is (2 × 10.294) ÷ 360 = 0.057 = 5.7%.

  In FIG. 4, the incident range from the heating source 3 of the one reflecting mirror 1 to the other reflecting mirror 2 (1) is a range indicated by hatching. When the incident range in this case is θ1, the energy loss can be calculated at 2θ1 / 360 °. For example, if θ1 is 15 °, the energy loss is (2 × 15) ÷ 360 = 0.083 = 8.3%.

  On the other hand, in the conventional single crystal growing apparatus shown in FIGS. 5 and 6, etc., the other spheroid mirror 52 (51) of the radiant heat from the heating source 53 (54) of one spheroid mirror 51 is used. The energy loss of the radiant heat from the heating source 53 (54) for melting the sample is large.

  That is, in FIG. 8, the incident range from the heating source 3 of one reflecting mirror 1 to the other reflecting mirror 2 (1) is a range indicated by hatching. If the incident range in this case is α, the energy loss can be calculated at 2α / 360 °. For example, if α is 41.134 °, the energy loss is (2 × 41.134) ÷ 360 = 0.229 = 22.9%. In FIG. 8, an evaporant adsorption jacket 64 is disposed around the upper crystal drive shaft 56.

  In FIG. 9, the incident range from the heating source 3 of the one reflecting mirror 1 to the other reflecting mirror 2 (1) is a range indicated by hatching. When the incident range in this case is α1, for example, if α1 is 460 °, the energy loss is (2 × 60) ÷ 360 = 0.333 = 33.3%.

  In the single crystal growing apparatus of the present invention, the energy loss of radiant heat from the heating source for melting the sample can be reduced, and the sample can be efficiently melted. For this reason, it is possible to grow a single crystal by stably melting in a short time with a heating source having a small capacity.

  b1 / a1 is set to 0.4 to 0.95, a1 / a2 is set to 0.5 to 1.0, and b1 / b2 is set to 0.3 to 0.80. By setting so that the second elliptical mirror 22 and the spherical mirror 23 are connected to each other on the extended line of the straight line L connecting the edge 41 on the stepped portion 40 side of the elliptical mirror 21, the energy of the radiant heat is set. A single crystal growing apparatus capable of reducing loss can be stably provided.

  As in the above-described embodiment, the reflecting mirror 1 (2) is formed of a plurality of block bodies, thereby forming the reflecting mirror 1 (2) including the first ellipsoidal mirror 21, the second ellipsoidal mirror 22, and the spherical mirror 23. Can be manufactured accurately and stably. In addition, in the above embodiment, each block body is fastened by a bolt member, so that separation and assembly can be easily performed. For this reason, each block body can be replaced and maintained, and a single crystal growing apparatus can be provided stably over a long period of time.

  As described above, the embodiment of the present invention has been described, but various modifications are possible without being limited to the embodiment. For example, in the embodiment, the evaporative material adsorption jacket 14 is arranged. Such a jacket may be omitted. If omitted, either one or both may be used. Further, in the case of configuring the reflecting mirror, in the above-described embodiment, it is configured by four block bodies, but the number of block bodies to be used is not limited to four. If manufacture is possible, you may comprise by one block body.

DESCRIPTION OF SYMBOLS 1, 2 Reflecting mirror 3, 4 Heating source 10 Surrounding tube 21 Ellipsoidal mirror 22 Ellipsoidal mirror 23 Spherical mirror 40 Step part 42 Connection part 50 Single crystal growth apparatus F0 Focus F1, F2 Focus

Claims (4)

A pair of reflecting mirrors each having a pair of focal points and arranged so that one focal point coincides, and a heating source disposed at the other focal point of the reflecting mirror, And a single crystal growing apparatus that grows a single crystal by irradiating a sample arranged at one focal point of the reflecting mirror with a reflecting mirror.
Each reflecting mirror is disposed between the first ellipsoidal mirror, the second ellipsoidal mirror disposed on the outer diameter side of the first ellipsoidal mirror, and the first ellipsoidal mirror and the second ellipsoidal mirror. The focal point of the first ellipsoidal mirror and the focal point of the second ellipsoidal mirror are the same, this focal point is the focal point of this reflecting mirror, and the center of the spherical mirror is disposed with the heating source. The spherical mirror and the second ellipsoidal mirror are continuous with each other, and a step portion is formed between the first ellipsoidal mirror and the spherical mirror to surround the sample placed at one focal point. A single crystal growing apparatus characterized in that the minimum gap dimension between the first ellipsoidal mirror and the outer diameter dimension of the surrounding tube is 8.0% to 120%.   2. The single crystal according to claim 1, wherein the first ellipsoidal mirror has a major axis of a1 and a minor axis of b1 and b1 / a1 of 0.4 to 0.95. Training device.   In the first ellipsoidal mirror, when the major axis is a1, the minor axis is b1, and in the second ellipsoidal mirror, the major axis is a2, and the minor axis is b2, and a1 / a2 is 0. The single crystal growth apparatus according to claim 1, wherein the single crystal growth apparatus is 0.5 to 1.0 and b1 / b2 is 0.3 to 0.80.   4. A connecting portion of a second ellipsoidal mirror and a spherical mirror is provided on an extension of a straight line connecting one focal point and an edge on the stepped portion side of the first ellipsoidal mirror. The single crystal growth apparatus of any one of these.

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