JP4219779B2 - Single crystal growth method and apparatus - Google Patents

Description

  The present invention relates to a method and an apparatus for growing a single crystal, and more specifically, when a single crystal is grown by a floating method using a concentrated heating method, an appropriate melting zone can be formed according to the size of the single crystal to be grown. The present invention relates to a method and apparatus for growing a single crystal that can increase the diameter of the material.

  When growing a single crystal, it is known to use a floating zone type single crystal growing apparatus (see, for example, Patent Document 1).

  An example of this floating zone type single crystal growth apparatus is shown in FIG. 7 is a longitudinal front view of a double elliptical single crystal growth apparatus 40 using a halogen lamp as a heat source, FIG. 8 is a cross-sectional view taken along line BB in FIG. 7, and FIG. The enlarged front view of is shown.

The single crystal growing apparatus 40 includes two symmetrical spheroid mirrors 41 and 42, which are coupled to face each other so that the respective focal points F ₀ and F ₀ coincide with each other to constitute a heating furnace. The inner surfaces of the spheroid mirrors 41 and 42, that is, the reflecting surfaces are subjected to gold plating in order to reflect infrared rays with high reflectivity. Near the other focal points F ₁ and F _{2 of the} spheroid mirrors 41 and 42, heating sources, for example, infrared lamps 43 and 44 such as halogen lamps are fixedly arranged. A heated portion 45 is positioned at the coincident focal point F ₀ of each of the spheroid mirrors 41 and 42, and a raw material rod 47 fixed to the lower end of the upper crystal drive shaft 46 extending in the vertical direction from above, and a vertical direction from below. A seed crystal rod 49 fixed to the upper end of the extending lower crystal drive shaft 48 is abutted. The upper crystal drive shaft 46 and the lower crystal drive shaft 48 are hermetically held by holding members 50 and 51 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.

The space m ₁ in which the raw material rod 47 and the seed crystal rod 49 are arranged is partitioned from the space m ₂ in which the infrared lamps 43 and 44 are arranged, and a transparent quartz tube 53 that forms a single crystal growth chamber 52 is provided. The single crystal growth chamber 52 is filled with an inert gas suitable for crystal growth, while the infrared lamps 43 and 44 are air-cooled in order to turn on the infrared lamps 43 and 44 safely.

As described above, the space m ₁ limited by the quartz tube 53 in the spheroid mirrors 41 and 42 is used as the single crystal growth chamber 52, so that the quartz tube 53 is not provided and the spheroid mirrors 41 and 42 are not provided. Compared with the case where the entire heating furnace is a single crystal growth chamber, the volume of the single crystal growth chamber 52 is remarkably reduced. Therefore, the single crystal growth chamber 52 is replaced with a predetermined single crystal growth atmosphere in a short time. And the atmospheric state can be easily maintained.

According to the single crystal growing apparatus 40, infrared rays irradiated from the infrared lamps 43 and 44 arranged at the first and second focal points F ₁ and F ₂ of the spheroid mirrors 41 and 42 are converted into the spheroids. is reflected by the surface mirror 41, it is focused on the heated portion 45 located in a common focal point F ₀ to infrared heating. By bringing the lower end of the raw material rod 47 and the upper end of the seed crystal rod 49 of the heated portion 45 into contact with each other smoothly by heating and melting the radiant energy by the infrared heating, as shown in FIG. A floating zone 54 is formed in the heated portion 45 between the crystal rods 49.

  Then, the upper crystal drive shaft 46 with the raw material rod 47 fixed at the lower end and the lower crystal drive shaft 48 with the seed crystal rod 49 fixed at the upper end are rotated together and slowly moved downward with synchronization or relative speed. As a result, the floating zone 54 between the raw material rod 47 and the seed crystal rod 49 is gradually moved toward the raw material rod 47, and the crystal grows to grow a single crystal. 9, 47a indicates a solid-liquid interface on the raw material rod 47 side, and 49a indicates a solid-liquid interface on the seed crystal rod 49 side.

If such a floating zone type single crystal growth apparatus 40 is used, infrared rays irradiated from infrared lamps 43 and 44 such as halogen lamps are reflected on the entire surfaces of the spheroid mirrors 41 and 42, and a common focus F is obtained. _Since the infrared rays are heated by being condensed on the heated portion 45 positioned at ₀ , the heated portion 45 can be heated to a high temperature with the small infrared lamps 43 and 44 having a relatively low output. By controlling the input power of 44, the temperature of the heated portion 45 can be easily and reliably controlled.

  Further, since the single crystal can be grown in a floating state in which the melt of the raw material rod 47 and the seed crystal rod 49 does not come into contact with other substances, the purity of the single crystal grown by the impurities eluted from the crucible compared to the crucible type A high-purity single crystal can be easily grown without lowering the thickness.

Japanese Patent Laid-Open No. 3-88790 (2nd page, upper left column, FIGS. 5 and 6)

  By the way, in the conventional single crystal growth apparatus 40, since the infrared lamps 43 and 44 which are heating sources use what was decided for each single crystal growth apparatus 40, the single crystal to be grown When the diameter is changed, the infrared lamps 43 and 44 corresponding to the diameter must be used, and continuous growth from a single crystal having a small diameter to a single crystal having a large diameter is difficult.

In the conventional single crystal growth apparatus 40, the infrared lamps 43 and 44 use a single coiled filament 55 as shown in FIG. There is a problem that single crystal with a diameter of about% is limited, and a single crystal with a larger diameter cannot be grown. Incidentally, for example, when a coiled filament having a diameter of 7 mm × length of 24 mm is used, the diameter of φ12 mm is the limit for high-quality single crystal growth of TiO ₂ with a diameter of φ12 mm and the superconductive material Bi ₂ Sr ₂ CaCu ₈₊ δ. Met. Further, when a coiled filament having a diameter of 14 mm and a length of 25 mm was used, the diameter of the intermetallic compound TiAl was limited to 16 mm.

  On the other hand, even when an infrared lamp with a coiled filament having a large diameter was used, it was difficult to grow a high-quality single crystal. That is, when a single crystal is grown, a high-quality single crystal cannot be grown unless a single crystal having a large diameter is first grown gradually from a small-diameter crystal rod. Appropriate heating is essential in the process of growing from a crystal rod to a large-diameter single crystal. However, even if a coil-shaped filament having a large diameter is used from the beginning, the height dimension H of the floating zone 54 of the heated portion 45 is only excessively high when the diameter of the raw material rod 47 and the seed crystal rod 49 is small. There was a problem that the melt could not be obtained due to gravity and the single crystal having a large diameter could not be grown.

  Accordingly, the present invention provides a single crystal growth capable of growing a single crystal having a large diameter from a single crystal having a small diameter by performing appropriate heating in the growth process from the single crystal having a small diameter to a single crystal having a large diameter. It is an object of the present invention to provide a method and a single crystal growing apparatus.

  In order to solve the above-mentioned problems, the method for growing a single crystal of the present invention includes a spheroid mirror, a heating source disposed at one focal point of the spheroid mirror, and an infrared ray from the heating source. In the single crystal growth method for growing a single crystal by irradiating a raw material rod and a seed crystal rod that are reflected at the other focal point and growing a single crystal, the heating source is a planar state of a plurality of coiled filaments, and The coils are arranged side by side in the horizontal direction, and the plurality of coiled filaments are selectively used according to the size of a single crystal to be grown (claim 1).

  The method for growing a single crystal according to the present invention includes a spheroid mirror, a heating source disposed at one focal point of the spheroid mirror, and the infrared light of the heating source reflected by the spheroid mirror. In the method of growing a single crystal by irradiating a raw material rod and a seed crystal rod arranged at the focal point, the heating source is arranged such that adjacent coiled filaments are vertically arranged in a staggered manner, and as a whole A plurality of coiled filaments are arranged in the transverse direction and are selectively used according to the size of the single crystal to be grown (claim 2).

  Here, the term “adjacent coiled filaments are arranged in a staggered manner and arranged in a lateral direction as a whole” includes, for example, a plurality of coiled filaments, This includes the case where filaments adjacent to each other are arranged vertically in a zigzag manner, and a plurality of coiled filaments are arranged in the lateral direction in plan view as a whole.

  In addition, the method for growing a single crystal according to the present invention is characterized by gradually increasing the power when the coiled filament is energized (Claim 3).

  Here, the term “gradually increasing the electric power during energization” is sufficient as long as the electric power of the filament during energization is gradually increased. When the voltage is increased gradually, the current is increased gradually, or both the voltage and current are increased. Any of the cases of gradually increasing is included.

  In the single crystal growth method of the present invention, when a single crystal having a plurality of heating sources and a large diameter is grown, a part of the plurality of heating sources is displaced upward in the heated portion. By expanding the heating region to the seed crystal rod side, the solid-liquid interface on the seed crystal rod side is prevented from rising (Claim 4).

  The term “part of heating sources among the plurality of heating sources” means, for example, one of the two heating sources in the case of a bi-elliptical single crystal growth apparatus, and is a four-elliptic type. In the case of a single crystal growth apparatus, it means a set of opposed heating sources among the four heating sources.

  The single crystal growth apparatus of the present invention includes a spheroid mirror, a heating source disposed at one focal point of the spheroid mirror, and the infrared ray of the heating source reflected by the spheroid mirror to the other focal point. In the single crystal growing apparatus for irradiating the arranged raw material rod and seed crystal rod to grow a single crystal, the heating source has a plurality of coiled filaments juxtaposed in a plane and arranged in a horizontal direction. The plurality of coiled filaments are connected to individual power sources (claim 5).

  Further, the single crystal growing apparatus of the present invention includes a spheroid mirror, a heating source arranged at one focal point of the spheroid mirror, and infrared rays of the heating source reflected by the spheroid mirror. In a single crystal growth apparatus for irradiating a raw material rod and a seed crystal rod arranged at a focal point to grow a single crystal, the heating source includes a plurality of coiled filaments arranged laterally and vertically, and as a whole A plurality of coiled filaments are arranged in the horizontal direction and connected to individual power sources. (Claim 6)

  Here, the term “a plurality of coiled filaments are arranged in the horizontal direction and in the vertical direction and arranged in the horizontal direction as a whole” is, for example, a filament adjacent in the horizontal direction as described above. Are arranged in a zigzag pattern above and below, and a plurality of coiled filaments as a whole are arranged in the lateral direction in plan view.

  In the single crystal growth apparatus of the present invention, the power source is a variable power source capable of gradually increasing the power (Claim 7).

  Here, the term “power variable power supply” includes any of a voltage variable power supply, a current variable power supply, and a voltage / current variable power supply.

  In addition, the single crystal growing apparatus of the present invention is characterized in that a plurality of the heat sources are provided, and a part of the heat sources can be displaced upward (Claim 8).

  According to the single crystal growth method described above, according to the diameter of the single crystal to be grown, in the case of a single crystal having a small size, only the coiled filament at the center is energized, and the cross-sectional area of the heating area of the heated portion is determined. When the diameter of the single crystal to be grown is small and large, energize the coiled filament in the center and the coiled filaments on the left and right sides, and increase the cross-sectional area of the heated area of the heated part, thereby reducing the diameter From a single crystal to a single crystal having a large diameter.

  By the way, when the diameter of the single crystal to be grown increases, the height of the floating zone becomes smaller and the viscosity of the melt in the floating zone under the same radiation energy as compared to the growth of a single crystal having a small diameter. And the melt may erode out between the raw material rod and the seed crystal rod and fall.

  Further, as the diameter of the single crystal to be grown increases, a phenomenon occurs in which the solid-liquid interface on the seed crystal rod side rises. The reason why such a solid-liquid interface on the side of the seed crystal rod rises is that the grown single crystal has a higher density than the porous raw material rod, and each molecule is bonded. Heat conduction and heat radiation from the crystal surface increase, and the amount of heat released from the crystal increases. As a result, the temperature on the seed crystal rod side decreases, and the solid-liquid interface on the seed crystal rod side becomes more By moving inside the floating zone (central part) of the hot part. If the diameter of the single crystal is not so large, the rise phenomenon of the solid-liquid interface on the seed crystal rod side is not remarkable, but if the diameter of the single crystal is increased, the rise phenomenon of the solid-liquid interface on the seed crystal rod side It becomes noticeable.

  According to the above-mentioned single crystal growth method, adjacent coiled filaments are not horizontal, but can be arranged in a staggered pattern with a slight difference in elevation, but the upper and lower staggered coiled filaments are Infrared light is condensed on the other focal point by the spheroid mirror, so that the heating area of the heated part can be formed with a thickness in the vertical direction, and the zone height cannot be gained simply by arranging a plurality of thin filaments. Therefore, the heating element is arranged in two stages, for example in a zigzag pattern, and the heating element is maintained to increase the heating volume, thereby stably maintaining the melt during growth.

  Further, according to the single crystal growth method for gradually increasing the power during energization of the coiled filament, the power supplied to the coiled filament is gradually increased in accordance with the increase in the diameter of the single crystal during the single crystal growth process, Heating suitable for the diameter of the single crystal at the time can be performed, and a single crystal having a large diameter can be continuously grown from a single crystal having a small diameter more smoothly.

  Further, when growing a single crystal having a plurality of heating sources and a large diameter, a part of the plurality of heating sources is displaced upward to expand the heating region in the heated portion to the seed crystal rod side. As a result, the rise of the solid-liquid interface on the seed crystal rod side can be prevented.

  As described above, when the diameter of the single crystal to be grown increases, the height of the floating zone decreases and the viscosity of the melt in the floating zone increases as compared to the growth of a single crystal with a small diameter. In some cases, the liquid is likely to fall out between the raw material rod and the seed crystal rod and fall. Further, as the diameter of the single crystal to be grown increases, a phenomenon occurs in which the solid-liquid interface on the seed crystal rod side rises due to a temperature drop near the solid-liquid interface on the seed crystal rod side.

  According to the single crystal growth method described above, when the diameter of the single crystal to be grown is small, the single-crystal is grown by energizing the coiled filament at the center. Energizing the filament to increase the cross-sectional area of the heated area of the heated part and displace some heating sources upward, thereby lowering the heated area of the heated part, that is, the seed crystal rod side The height of the floating zone is expanded to the seed crystal rod side to prevent the solid crystal / liquid interface on the seed crystal rod side from rising due to the large diameter of the single crystal, and the single crystal is smoothly enlarged. Can be calibrated.

  The single crystal growth apparatus of the present invention includes a spheroid mirror, a heating source disposed at one focal point of the spheroid mirror, and the infrared ray of the heating source reflected by the spheroid mirror to the other focal point. In the single crystal growing apparatus for irradiating the arranged raw material rod and seed crystal rod to grow a single crystal, the heating source has a plurality of coiled filaments juxtaposed in a plane and arranged in a horizontal direction. Since the plurality of coiled filaments are connected to individual power sources, when growing a single crystal having a small diameter, only the coiled filament in the center is energized and the heating area of the heated part is cut off. When growing a single crystal with a small diameter from a single crystal with a small diameter, in addition to the coiled filament at the center, the coiled filaments on both the left and right sides are energized by separate power supplies and heated The cross-sectional area of the heating zone By listening, it is possible to smoothly grown from a single crystal of small-diameter up to a single crystal of large diameter

  Further, the single crystal growing apparatus of the present invention includes a spheroid mirror, a heating source arranged at one focal point of the spheroid mirror, and infrared rays of the heating source reflected by the spheroid mirror. In a single crystal growth apparatus for irradiating a raw material rod and a seed crystal rod arranged at a focal point to grow a single crystal, the heating source includes a plurality of coiled filaments arranged laterally and vertically, and as a whole Since the plurality of coiled filaments are arranged in the horizontal direction and these coiled filaments are connected to individual power supplies, the plurality of coiled filaments are not horizontally arranged but arranged in a staggered pattern with a slight difference in elevation. In contrast to a configuration in which a plurality of coiled filaments are arranged in a horizontal row (horizontal state), the heating area of the heated portion formed by these coiled filaments has a thickness in the vertical direction. Therefore, when a single crystal having a large diameter is grown, the vicinity of the solid-liquid interface on the seed crystal rod side is sufficiently heated by the heating region having a thickness above and below, so that the solid-liquid interface on the seed crystal rod side is sufficiently heated. A single crystal having a large diameter can be grown smoothly by preventing the rising.

  In the single crystal growth apparatus of the present invention, since the power source is a power variable power source that can gradually increase the power, the coil filament is applied to the coil filament according to the increase in the diameter of the single crystal in the single crystal growth process. By gradually increasing the energizing power, the optimum heating can be performed for the diameter of the single crystal at that time, and a single crystal having a large diameter can be continuously grown from a single crystal having a small diameter more smoothly.

  In the single crystal growth apparatus of the present invention, the plurality of heating sources are configured such that a part of the heating sources can be displaced upward. Even if the solid-liquid interface rises, by displace some heating sources upward, the heating area of the heated part is expanded downward, that is, to the seed crystal rod side, and the heating area, that is, the floating zone By expanding the height dimension to the seed crystal rod side and sufficiently heating the vicinity of the solid-liquid interface on the seed crystal rod side, it is possible to prevent the solid-liquid interface on the seed crystal rod side from rising, The diameter can be increased smoothly.

  Hereinafter, embodiments of a single crystal growth method and a single crystal growth apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a schematic longitudinal front view of a main part of a double elliptical single crystal growing apparatus 10 using an infrared lamp having a coiled filament as a heating source, which will be described later, and FIG. 2 is a diagram of the single crystal growing apparatus 10 of FIG. The schematic cross-sectional view which follows an AA line is shown.

The single crystal growing apparatus 10 includes two symmetrical spheroid mirrors 11 and 12. Each spheroid mirror 11, 12 has one focal point F ₁ , F ₂ and the other focal point F _0, and is heated by being coupled oppositely so that the other focal point F ₀ (see FIG. 2) coincides. It constitutes a furnace. The inner surfaces of the spheroid mirrors 11 and 12, that is, the reflection surfaces are subjected to gold plating in order to reflect infrared rays with high reflectivity.

Infrared lamps 13 and 14 such as halogen lamps having coiled filaments, which will be described later, are fixedly arranged in the vicinity of one of the focal points F ₁ and F _{2 of the} spheroid mirrors 11 and 12. A heated portion 15 is located at the other focal point F ₀ where the spheroid mirrors 11 and 12 coincide with each other, and a quartz tube 16 is installed in the vertical direction so as to include the heated portion 15.

  The quartz tube 16 is suitable for growing a single crystal by dividing the inner part m1 of the quartz tube 16 from the inner parts m2 of the other spheroid mirrors 11 and 12 by dividing the inner part m1 of the quartz tube 16 into a single crystal. The atmosphere is replaced and the atmospheric state is easily maintained. On the other hand, it is useful for cooling the infrared lamps 13 and 14 of the inner part m2 in each of the spheroid mirrors 11 and 12 without affecting the heated part 15 in the inner part m1 of the quartz tube 16. .

In the heated portion 15 located at the coincident focal point F ₀ of each spheroid mirror 11, 12, the raw material rod 18 fixed to the lower end of the upper crystal drive shaft 17 extending in the vertical direction from above, and extending in the vertical direction from below. A seed crystal rod 20 fixed to the upper end of the lower crystal drive shaft 19 is abutted. The upper crystal drive shaft 17 and the lower crystal drive shaft 19 are hermetically held by holding members 21 and 22 as shown in the figure, and can be freely rotated by a drive motor such as a servo motor (not shown) and synchronized or relative to each other. It has a speed and is held up and down.

In the single crystal growth apparatus 10 described above, the infrared lamps 13 and 14 each have a plurality of (four in the illustrated example) coiled filaments 23a, 23b, 23c, and 23d juxtaposed in a plane, as shown in FIG. and they are arranged in a horizontal direction (lateral direction) in the vicinity of the focal point F _1, F ₂ of one of the single crystal growing apparatus 10. The plurality of coiled filaments 23a to 23d are encapsulated by quartz 24, for example, coiled filaments 23a and 23b at the center are connected in series, and coiled filaments 23c and 23d on both sides (left and right) are connected in series. Terminal portions 25 and 26 are provided at both ends of the series connection of the coiled filaments 23a and 23b in the central portion, and terminal portions 27 are provided at both ends of the series connection of the coiled filaments 23c and 23d on both sides (left and right). , 28.

  The terminal portions 25 and 26 connected in series between the coiled filaments 23a and 23b at the center are connected to the power source (V1) 29, and the terminal portions 27 and 28 connected in series between the coiled filaments 23c and 23d on both sides (left and right). Are selectively connected to a power supply (V2) 30.

  Therefore, a heating region having a small cross-sectional area is formed in the heated portion 15 by energizing only the coiled filaments 23a and 23b in the central portion by the power source (V1) 29. Next, when the coiled filaments 23c and 23d on both sides (left and right) are energized by the power source (V2) 30 while the centrally connected coiled filaments 23a and 23b connected in series are energized, The radiation energy by energization of the coiled filaments 23c and 23d on both sides (left and right) is added to the radiation energy by energization of the filaments 23a and 23b, so that the cross-sectional area of the heating area in the heated portion 15 can be increased.

Next, the operation of the single crystal growing apparatus 10 will be described. First, after replacing the inside of the quartz tube 16 with an appropriate atmosphere such as an inert gas, the coils at the center of the infrared lamps 13 and 14 disposed in the vicinity of one of the focal points F ₁ and F _{2 of the} spheroid mirrors 11 and 12. Jo filaments 23a, and energized only by the power supply (V1) 29 23b, the infrared ray emitted from the infrared lamps 13 and 14, is reflected by the spheroidal mirror 11, at the focal point F ₀ of the common of the other The heated part 15 is condensed and heated by infrared rays. By making the lower end of the raw material rod 18 of the heated portion 15 and the upper end of the seed crystal rod 20 heat and melt smoothly by the radiation energy by this infrared heating, as shown in FIG. A floating zone (hereinafter referred to as “FZ”) 31 having a small cross-sectional area is formed in the heated portion 15 between 18 and the seed crystal rod 20.

  In FIG. 4A and later-described FIG. 4B, the coil filaments 23a to 23d are actually arranged in a direction orthogonal to the axial direction (paper surface) of the raw material rod 18 and the seed crystal rod 20. However, since it is difficult to understand the difference between FIG. 4 (A) and FIG. 4 (B) on the drawing if it is drawn as such, it is drawn parallel to the paper surface for convenience of explanation.

  Then, the upper crystal drive shaft 17 with the raw material rod 18 fixed to the lower end and the lower crystal drive shaft 19 with the seed crystal rod 20 fixed to the upper end are rotated together (for example, 20 to 30 rpm) and slowly in synchronization. By moving downward, the FZ 31 formed in the heated portion 15 between the raw material rod 18 and the seed crystal rod 20 is gradually moved to the raw material rod 18 side, and a single crystal is grown. In FIG. 4A, 18a indicates a solid-liquid interface on the raw material rod 18 side, and 20a indicates a solid-liquid interface on the seed crystal rod 20 side.

At this time, since the infrared lamps 13 and 14 are energized only to the coiled filaments 23a and 23b at the center, the cross-sectional area of the infrared heating region condensed on the heated portion 15 is small. The diameter dimension is small, and the diameter D _{1 of the} single crystal that can be grown is small.

When a single crystal having a small diameter can be grown as described above, the single crystal having a small diameter is then enlarged. For this purpose, the upper crystal drive shaft 17 with the raw material rod 18 fixed to the lower end and the lower crystal drive shaft 19 with the seed crystal rod 20 fixed to the upper end are lowered with a relative speed. For example, by making the descending speed of the upper crystal drive shaft 17 with the raw material rod 18 fixed to the lower end larger than the descending speed of the lower crystal drive shaft 19 with the seed crystal rod 20 fixed to the upper end, both crystal drive shafts 17, Based on the lowering speed difference of 19, the diameter dimension of the FZ31 gradually increases, and as a result, the single crystal can be made large diameter (D ₂ ).

  As described above, instead of the method using the difference in descending speed between the crystal drive shafts 17 and 19, the shape of the raw material rod 18 is previously formed in a different shape so that the lower end is thin and becomes thicker as it goes up. By preliminarily, the descending speeds of both crystal drive shafts 17 and 19 can be made equal to enable a large diameter.

In order to appropriately heat and form the large-diameter FZ31 together with the above-mentioned large-diameter FZ31, as shown in FIG. 4B, left and right coiled filaments 23c, It also energizes 23d. Then, in addition to the radiant energy of the coiled filaments 23a and 23b in the central part, the radiant energy of the left and right coiled filaments 23c and 23d is also irradiated. Compared with the case where the cross-sectional area of the infrared heating region irradiated to the heated portion 15 is increased and only the coiled filaments 23a and 23b at the center are energized, the FZ31 having an increased diameter is appropriately heated. For example, a single crystal having a diameter D ₂ of about 25 mm can be grown.

  In addition, when energizing the central filaments 23a and 23b by the power source (V1) 29 and energizing the filaments 23c and 23d on both sides (left and right) by the power source (V2) 30, the power variable power source, for example, the voltage variable power source When the diameter of the single crystal is relatively small, the power source (V1) 29 is energized at a relatively low voltage, the applied voltage is gradually increased as the diameter increases, and the diameter reaches a predetermined value. When the voltage reaches the power source (V2) 30 and the applied voltage is gradually increased as the diameter increases, the crystal in the cross-sectional area of the heating region suitable for the diameter of the single crystal can be obtained in the process of growing the single crystal. Can be nurtured.

  In the process of increasing the diameter of the FZ 31 in FIG. 4B, the area A corresponds to the process of gradually increasing the power by the voltage variable power supply (V1) 29 and the area B is the voltage variable power supply (V1). 29 is a portion corresponding to a process of further increasing the diameter by gradually increasing the electric power by the voltage variable power supply (V2) 30.

  By selectively energizing the plurality of coiled filaments 23a to 23d as described above, it becomes possible to continuously grow from a single crystal having a small diameter to a single crystal having a large diameter. In addition, by using a power variable power source capable of gradually increasing the power as the power source, it becomes possible to gradually increase the cross-sectional area of the heating region as the diameter of the FZ31 increases, and grow single crystals. In the process, a single crystal having a large diameter can be grown more smoothly from a single crystal having a small diameter by performing optimum heating as the diameter increases.

  In the above-described embodiment, the filaments of the infrared lamps 13 and 14 have been described as having four coiled filaments 23a to 23d, but may have any number of coiled filaments. As the number of coiled filaments increases, it becomes possible to grow smoothly up to a single crystal having a larger diameter by selecting and using coiled filaments at the center, middle and both ends accordingly.

  Moreover, the number of coil-shaped filaments may be not only an even number but also three or five or more odd numbers. That is, the central portion is, for example, a single coiled filament, and selectively used in the middle portion on both sides and further on both end portions on the both sides. Similarly, from a single crystal having a small diameter to a single crystal having a larger diameter. Can be cultivated. In this way, when the central coiled filament is made into one piece, for example, the diameter of the coiled filament at the center is set different from the diameter of the coiled filament at the middle or both sides. You can also.

  Note that when the coiled filaments 23a and 23b at the center and the left and right coiled filaments 23c and 23d are energized by individual power sources (V1) 29 and (V2) 30, the left and right coiled filaments 23c and 23d are energized. The supply power (supply voltage and / or supply current) can be made different from the supply power (supply voltage and / or supply current) of the coiled filaments 23a, 23b at the center.

  The power supplies (V1) 29 and (V2) 30 are preferably DC stabilized power supplies, but single-phase or multiphase AC power supplies and high-frequency power supplies can also be used.

  Further, in the process of increasing the diameter of the single crystal, as the diameter of the single crystal increases, the heating energy in the vicinity of the solid-liquid interface 20a on the seed crystal rod 20 side is insufficient, and the solid-liquid interface on the seed crystal rod 20 side. When the phenomenon that 20a rises is recognized and the height dimension of the heated region of the heated portion 15 is small, the solid-liquid interface 20a on the seed crystal rod 20 side is prevented from rising and a good FZ31 may not be formed. .

  As a countermeasure against the rising of the solid-liquid interface 20a on the side of the seed crystal rod 20 as described above, for example, a plurality of adjacent filaments can be arranged in a staggered manner with respect to each other.

  Infrared lamps 13 'and 14' shown in FIGS. 5 (A) and 5 (B) have the first and third coiled filaments 23g and 23f out of the four coiled filaments 23e to 23h. The second and fourth coiled filaments 23e and 23h are arranged below, and a plurality of adjacent coiled filaments 23e to 23h are arranged in a zigzag shape above and below each other.

  By arranging in such an upper and lower zigzag shape, the radiant energy density of the heated portion 15 can be increased, and the height of the heating area of the heated portion 15 can be increased, and the solid liquid on the seed crystal rod 20 side can be expanded. It is possible to sufficiently heat the vicinity of the interface 20a to prevent the solid-liquid interface 20a on the seed crystal rod 20 side from rising, and to smoothly increase the diameter of the single crystal.

Furthermore, since the radiant energy of the infrared lamps 13 and 14 is reflected by the ellipsoidal mirrors 11 and 12 and inverted up and down to the focal point F ₀ , for example, the plurality of coiled filaments 23 are planarized. Among the arranged infrared lamps 13 and 14, one of the infrared lamps 13 or 14 is increased in power supply when the single crystal having a large diameter is grown, and is displaced upward to lower the heating area of the heated portion 15. That is, it can be expanded to the seed crystal rod 20 side.

FIGS. 6A to 6E show the state of each stage when the diameter of the single crystal is increased by displacing the infrared lamp 13 or 14 upward as described above. As shown in FIG. 6 (A), an infrared lamp 13, 14 is arranged in a fixed position, the coiled filament 23a of the central portion, by energizing the 23b, and the raw material rod 18 of diameter D ₁ at the heated portion 15 A single crystal having a small diameter D ₁ is grown by forming and moving an FZ 31 ₁ having a height dimension H _{1 on} the seed crystal rod 20.

Next, as shown in FIG. 6B, the relative speeds of the upper crystal drive shaft 17 and the lower crystal drive shaft 19 are made different while gradually increasing the power supplied to the coiled filaments 23a and 23b at the center. Thus, the FZ31 ₂ having the height dimension H ₂ is formed in the heated portion 15, and the diameter D ₂ (> D ₁ ) of the single crystal is gradually increased. At this time, the height dimension H ₂ of the FZ31 ₂ becomes smaller than H _{1 due} to the gradual increase of the diameter D ₂ of the single crystal.

Next, as shown in FIG. 6C, when the power supplied to the coiled filaments 23a and 23b at the center reaches a predetermined value, the power supplied to the coiled filaments 23c and 23d on both sides is gradually increased while being heated. By forming FZ31 ₃ having a height dimension of H _{3 in} the region 15, a single crystal having a large diameter D ₃ (> D ₂ ) is grown by a dimension L ₁ . At this time, the height dimension H ₃ of FZ31 ₂ becomes smaller than H _{2 due} to the growth of a single crystal having a diameter of D ₃ .

Next, as shown in FIG. 6 (D), coiled filaments 23a of the central portion, the electric power supplied to 23b becomes a predetermined value, the height to form a FZ31 ₄ of H ₄ in the heated portion 15, A single crystal having a large diameter D ₃ is grown by a dimension L ₂ . At this time, the height dimension H ₄ of FZ31 ₄ becomes smaller than H _{3 due} to the growth of a single crystal having a diameter of D ₃ .

Then, since too narrow for FZ31 ₄ of height H ₄ is to grow a good single crystal, as shown in FIG. 7 (E), by displacing the position of the infrared lamp 13 or 14 above the the heating zone of the heating section 15 while expanding the seed crystal rod 20, increasing the electric power supplied to the infrared lamps 13 and 14, the heating condition of the heating zone and suitability of, FZ31 height dimension H _{5 5} And a single crystal having a large diameter D ₃ is grown to a dimension L ₃ . At this time, the expansion and increase in the power supplied heating zone, the height H ₅ in FZ31 ₅ is larger than H _4.

As described above, the feed rod 18 and the seed crystal rod 20 of the caliber D _1, selective use of a plurality of filaments 23 a to 23 d, increasing the energizing power to them filaments, the upper one of the infrared lamp 13 or 14 A single crystal having a large diameter D ₃ can be grown while gradually increasing its diameter (D) due to the displacement of the crystal.

  In addition, although the said embodiment demonstrated the bi-elliptical type single crystal growth apparatus, it is applicable also to a 4 elliptical type single crystal growth apparatus.

It is a vertical front view explaining the single crystal growth method and single crystal growth apparatus of embodiment of this invention. It is a cross-sectional view along the AA line in the single crystal growth apparatus of this invention shown in FIG. FIG. 2 is an enlarged plan view of a heating source in the single crystal growing apparatus of FIG. 1. (A) is a schematic plan view showing an energized state of a coiled filament at the central portion in the single crystal growth apparatus of FIG. 1 and an enlarged front view of a heated portion. (B) is a central portion in the single crystal growth apparatus of FIG. It is the typical top view which shows the energized state of the coiled filament of both sides, and the enlarged front view of a to-be-heated part. (A) is a top view which shows arrangement | positioning of the coiled filament of the different infrared lamp of the single crystal growth apparatus based on this invention, (B) is a side view of the coiled filament in the infrared lamp of (A). (A)-(E) are the principal part enlarged front views in each step which grows a large-diameter single crystal from a small-diameter single crystal. It is a vertical front view in the conventional single crystal growth apparatus. It is a cross-sectional view along the BB line in the single crystal growing apparatus of FIG. It is an enlarged front view of the to-be-heated part in the single crystal growth apparatus of FIG. FIG. 8 is an enlarged front view of a heated portion for explaining the relationship between the diameter d of a coiled filament and the diameter D of a single crystal that can be grown in the single crystal growth apparatus of FIG. 7.

Explanation of symbols

10 Single crystal growth apparatus 11, 12 Spherical ellipsoidal mirror 13, 14, 13 ', 14' Heat source (infrared lamp)
DESCRIPTION OF SYMBOLS 15 Heated part 16 Quartz tube 17 Upper crystal drive shaft 18 Raw material rod 18a Solid-liquid interface on the raw material rod side 19 Lower crystal drive shaft 20 Seed crystal rod 20a Solid-liquid interface on the seed crystal rod side 23a-23h Coiled filament 24 Quartz 25 to 28 terminal portions 29, 30 power supply 31, 31 _{1-31 5} floating zone (FZ)
D, D _{1 to} D ₃ single crystal diameter H, H _{1 to} H ₅ Floating zone (FZ) height dimensions

Claims (8)

A spheroid mirror, a heating source disposed at one focal point of the spheroid mirror, a raw material rod and a seed crystal rod disposed at the other focal point by reflecting the infrared rays of the heating source by the spheroid mirror In a single crystal growth method for growing a single crystal by irradiating
The heating source is configured by arranging a plurality of coiled filaments side by side in a plane and arranging them horizontally, and the plurality of coiled filaments are selectively selected according to the size of a single crystal to be grown. A method for growing a single crystal, characterized by being used in the above. A spheroid mirror, a heating source disposed at one focal point of the spheroid mirror, a raw material rod and a seed crystal rod disposed at the other focal point by reflecting the infrared rays of the heating source by the spheroid mirror In a single crystal growth method for growing a single crystal by irradiating
The heating source is configured by arranging adjacent coiled filaments vertically in a staggered manner and in the lateral direction as a whole, and the plurality of coiled filaments are grown to the size of a single crystal to be grown. A method for growing a single crystal, which is selectively used according to the method. The method for growing a single crystal according to claim 1, wherein the electric power during energization of the coiled filament is gradually increased. When growing a single crystal having a plurality of heating sources and a large diameter, a part of the heating sources among the plurality of heating sources is displaced upward to expand the heating region in the heated portion to the seed crystal rod side. 4. The method for growing a single crystal according to claim 1, wherein the solid-liquid interface on the seed crystal rod side is prevented from rising. A spheroid mirror, a heating source disposed at one focal point of the spheroid mirror, a raw material rod and a seed crystal rod disposed at the other focal point by reflecting the infrared rays of the heating source by the spheroid mirror In a single crystal growth apparatus that irradiates a single crystal to grow a single crystal,
The heating source is configured by arranging a plurality of coiled filaments side by side in a plane and horizontally, and the plurality of coiled filaments are connected to individual power sources. Crystal growth device. A spheroid mirror, a heating source disposed at one focal point of the spheroid mirror, a raw material rod and a seed crystal rod disposed at the other focal point by reflecting the infrared rays of the heating source by the spheroid mirror In a single crystal growth apparatus that irradiates a single crystal to grow a single crystal,
The heating source is configured by arranging a plurality of coiled filaments in the horizontal direction and the vertical direction, and as a whole in the horizontal direction, and connecting the plurality of coiled filaments to individual power sources. A single crystal growth device characterized. The single crystal growth apparatus according to claim 5 or 6, wherein the power source is a variable power source capable of gradually increasing the power. The single crystal growth apparatus according to claim 5, wherein a plurality of the heat sources are provided, and some of the heat sources are configured to be displaceable upward.

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