JP4793604B2 - Single crystal pulling method and pulling apparatus - Google Patents

Description

  The present invention relates to an apparatus for producing single crystals such as oxides, fluorides, and metal alloys used for so-called laser optical elements, nonlinear optical elements, medical scintillators, piezoelectric elements, giant magnetostrictive elements, and the like. More specifically, a pulling method for obtaining a desired crystal material while drawing a raw material melt from a hole provided at the lower end of the crucible, particularly a so-called micro pulling (μ-pD) method for obtaining a fiber-like single crystal. The present invention relates to a crystal manufacturing method and a single crystal pulling apparatus.

  A pull-out hole is formed in the lower end of the crucible holding the heated and melted raw material, crystal nuclei (hereinafter referred to as seeds) are brought into contact with the raw material melt leaked from the hole, and leakage of the raw material from the hole is caused. A so-called reduction method is known in which a single crystal that grows with the seed as a nucleus is obtained by lowering the seed. A single crystal obtained by this method has a smaller crystal diameter than a single crystal obtained by a so-called pulling method represented by a conventionally known CZ method. However, as a method for obtaining a single crystal having a short time required for crystal growth and excellent in crystallinity at a low cost as compared with the CZ method, it is necessary to modify the actual manufacturing equipment in terms of hardware and various single units. Application to crystals has been studied.

  In the pulling method, there is a so-called micro pulling method (see Patent Document 1 or 2) as a method for obtaining a fiber crystal having higher crystallinity and maintaining a high crystal growth rate. Using this method, production conditions for oxide single crystals such as alumina and calcia have been studied. Further, as disclosed in Patent Document 1, a method of controlling the shape of the cross section perpendicular to the pulling axis of the single crystal by devising the supply state of the raw material melt at the time of pulling down, or as disclosed in Patent Document 2 Also, a method for controlling the shape or quality of a single crystal has been devised for practical use, such as a method for improving the uniformity of composition change inside the crystal in a cross section perpendicular to the pulling axis direction.

JP 2003-095783 A JP 2008-239352 A

  In the above-described micro-pulling-down method, a rod-shaped single crystal is generally manufactured using various materials. However, in the actual manufacturing process, filling the crucible with raw materials, attaching the crucible to the device, exhausting the inside of the device and introducing a predetermined gas as needed, heating and melting the raw material, seed for the raw material melt leaking from the crucible Proper contact of the seed, pulling down the seed at an appropriate speed, slow cooling of the obtained single crystal and the device, opening of the device and taking out the single crystal are sequentially performed, and the resulting single crystal is developed on a commercial basis. In consideration of this, a reduction in the process time is also required.

  The present invention has been made in view of the above situation, and allows a plurality of single crystals to be grown from a single crucible, and allows suitable and stable production regardless of the operator of the production apparatus. An object of the present invention is to provide a single crystal pulling method and a pulling apparatus suitable for the method.

  In order to solve the above-described problems, the method for pulling down a single crystal according to the present invention includes a main body capable of holding a raw material and a melt of the raw material inside, and a raw material melt leaking in communication with the inside of the main body. A raw material melt leaked from each through-hole of the crucible having a plurality of through-holes is brought into contact with a seed for determining a crystal orientation when the raw material melt is crystallized, and the seed is pulled down along a predetermined pulling axis. A method for pulling down a single crystal to obtain a plurality of single crystals by loading raw materials into the crucible, bringing the seed into contact with the opening end face where the through hole opens, and pushing up the crucible by a predetermined amount along the pulling axis, The raw material is melted, and the raw material melt obtained by melting the raw material leaking from the openings of the plurality of through holes provided in the crucible is brought into contact with the seed, and a plurality of single crystals are grown by lowering the seed in the pulling direction. Specially It is set to.

  In the above-described method for pulling down the single crystal, the plane where the plurality of through-holes are open is in the same first plane, and the seed is in contact with the through-hole in the second plane facing the first plane. It is preferable to have the contact surface. Moreover, it is preferable that each of the plurality of through-holes is disposed on a protrusion that protrudes independently from the main body in the pull-down direction.

  In order to solve the above problems, a single crystal pulling device according to the present invention includes a main body capable of holding a raw material and a raw material melt therein, and a raw material melt leaking in communication with the inside of the main body. A plurality of possible through-holes, and a raw material melt leaked from each through-hole of the crucible having a seed that determines a crystal orientation when the raw material melt crystallizes, and contacts the seed along a predetermined pulling axis A single crystal pulling device that obtains a plurality of single crystals by pulling down, a work coil that is arranged by winding a crucible so that a high-frequency current can be conducted and a high-frequency magnetic field can be generated by the high-frequency current, and a raw material melt A seed holder that holds a seed that defines a crystal orientation when the crystallizes, a seed drive mechanism that drives the seed holder up and down along a pull-down axis, and a seed drive mechanism that allows the seed to It is characterized by having a crucible vertical position detection means for detecting a push-up amount at the time of pushing up quantified.

  In the single crystal pulling device described above, the planes where the plurality of through-holes are open are in the same first plane, and the seed is in contact with the through-hole in the second plane opposite to the first plane. It is preferable to have the contact surface. Moreover, it is preferable that each of the plurality of through-holes is disposed on a protrusion that protrudes independently from the main body in the pull-down direction. Alternatively, it is preferable that a groove having a width and a depth for preventing the interaction of the raw material melt leaking from the adjacent through hole is formed on the outer surface of the crucible where the through hole is formed.

  Theoretically, a plurality of through holes are arranged on the lower end surface of a single crucible, and a plurality of seeds corresponding to the through holes are brought down into contact with the raw material melt leaking from each of the through holes, and these are lowered theoretically. It is possible to grow a plurality of fiber-like single crystals simultaneously. However, in practice, it is difficult to perform so-called seed touch in which each of the plurality of seeds is simultaneously brought into contact with the raw material melt to obtain a suitable meniscus (solid-liquid boundary portion). Specifically, the crucible is set in a crucible state even when rigorous processing is performed so that the upper end surface of each seed exists in the same horizontal plane and the seed is precisely fixed to a specific jig. The seed touch varies due to various attachment errors existing in the growing apparatus. According to the present invention, instead of providing individual seeds for the openings of the plurality of crucible through-holes, by first using a plate-shaped seed, the positional relationship with each through-hole opening of each seed is stabilized. Yes.

  Furthermore, in the present invention, the seed touch surface which is the seed upper end surface is brought into surface contact with the opening surface of the through hole at the time of seed touch, and the seed is further raised by a predetermined amount from this state. That is, a flat seed is brought into contact with the lower end surface of the crucible, and then the crucible is lifted by a predetermined amount by the seed. By performing this operation, the seed touch surface can be in close contact with the opening formation surfaces of all the through holes regardless of the fixed arrangement of the crucible. The raw material in the crucible is heated and melted while maintaining such a predetermined amount of pushed-up state, and the raw material melt is leaked from each through hole. By performing this operation, it is possible to perform a suitable seed touch at all through-hole openings. By reducing the seed from this state, it is possible to perform uniform and suitable growth for a plurality of single crystals. Note that the meniscus has a certain thickness during the seed pulling operation. For example, when the single crystal to be obtained is an oxide-based material, the meniscus thickness is 1 mm or less. When the crucible is lifted by the seed, the predetermined lifting amount is preferably equal to or greater than the meniscus thickness, and when obtaining the exemplified oxide single crystal, the predetermined amount is preferably 1 mm. If the lifting amount is smaller than the meniscus, for example, if there is a part that is not partially lifted in the crucible, the seed touch in this part is not performed properly, but the other part does not. A meniscus is formed, and there is a possibility that the growth of the single crystal is not established at the portion.

  In addition, when trying to simultaneously pull down a plurality of single crystals, if the interaction due to the surface tension of the raw material melt leaking from each through hole is not hindered, the grown crystal is brought into contact with the individual raw material melts. There is a possibility that deformation or the like may occur. Therefore, it is considered necessary to prevent this interaction. In the present invention, the case where the contact surface between the raw material melt and the raw material melt in the crucible is a combination with a so-called good wettability is particularly suitable. In this case, there is a high possibility that the raw material melt spreads in a plane perpendicular to the pull-down axis at the time of seed touch and causes an interaction. Regarding the interaction of the raw material melt described here, the wettability between the contact regions of the raw material melt and the melt in the crucible is greatly affected. The wettability is a characteristic defined by the contact angle between the raw material melt obtained by dropping the raw material melt on the upper surface of the contact surface and the flat surface. In the present specification, the case where it becomes smaller is defined as a combination with good wettability.

  In the present invention, in the present invention, a plurality of through holes penetrating downward from the inside of the crucible are arranged at the lower end of the crucible with respect to the lower end surface of the crucible, and each opening of the through hole corresponds to the through hole. The protrusions projecting in the downward direction from the lower end surface of the crucible are provided on the lower flat surface in the downward direction. Further, the adjacent protrusions are provided so as to protrude independently from the crucible body at a predetermined interval so that the raw material melt does not interact with the surface tension at the temperature at the start of the pulling operation. . Thus, by providing the protrusions independently, the interaction of the raw material melt when leaking from the through holes is prevented. In this case, a groove having a width and a depth capable of preventing the interaction is arranged between the plurality of through-hole openings, and thereby the same effect as the above-described formation of the protrusion is effectively obtained. It is also good to get.

Further, according to the present invention, the seed touch is performed in a state where the seed is in close contact with the opening of the through hole, and the seed is lowered from the state. Therefore, from the initial stage of the pulling operation, the desired shape can be obtained from the beginning with respect to the shape of the cross section perpendicular to the pulling axis direction of the single crystal. For this reason, also about the single crystal obtained, the area | region deleted at the time of post-processing reduces, and it also becomes possible to maintain high manufacturing efficiency.
In addition, a member called a so-called cylindrical after-heater is disposed under the crucible in the pulling direction. The after heater defines a lowering space below the crucible and has a function of improving the temperature gradient and temperature distribution in the space so as to be suitable for the lowering conditions by generating heat. Therefore, it is preferable that the protrusions described above are arranged so as to satisfy the same conditions with respect to the inner wall surface of the after heater. Since the shaft center of the crucible and the shaft center of the after-heater are arranged so as to coincide with each other, it is preferable that these protrusions are provided at equal intervals around the shaft center. In addition, it is preferable that the projecting portion facing the inner wall surface of the after heater and the surface opposite to the facing surface are both disposed in a relatively uniform distribution range in the temperature distribution formed by the after heater. .

The method for pulling down a single crystal according to an embodiment of the present invention schematically shows the structure of the main part of one step in the method. The method for pulling down a single crystal according to an embodiment of the present invention schematically shows the structure of the main part of one step following the step shown in FIG. 1A in the method. The method for pulling down a single crystal according to an embodiment of the present invention schematically shows the structure of the main part of one step following the step shown in FIG. 1B in the method. The single crystal pulling-down method according to the embodiment of the present invention schematically shows the structure of the main part of one step following the step shown in FIG. 1C in the method. It is a figure which shows the axial direction cross section of the crucible used in the single crystal pulling-down method which concerns on one Embodiment of this invention. It is a figure which shows the state which looked at the crucible shown in FIG. 2A from the arrow 2B direction. It is a figure showing typically the main composition of the single crystal pulling device concerning one embodiment of the present invention.

  An embodiment of the present invention will be described below with reference to the drawings. 1A to 1D are diagrams schematically showing individual steps in a method for pulling down a single crystal according to an embodiment of the present invention. More specifically, regarding the system for pulling and growing six single crystals, the lower end of the crucible and the axial cross section of the seed are each schematically shown, and these operations are shown step by step. Before describing the steps shown in these drawings, the structure of the crucible 11 used in this embodiment will be described first. FIG. 2A is a view showing a cross section in the axial direction of the crucible 11 used in this embodiment, and FIG. 2B shows a state where the crucible 11 shown in FIG. 2A is viewed from the direction of the arrow 2B.

  The crucible 11 has a cylindrical shape in which one end (the end disposed below during the lowering operation) is closed by the lower end 11a. The crucible 11 constitutes a main body in the present invention by the cylindrical portion and the lower end portion 11a. A protrusion protruding toward the lower side (left side in the drawing) in the pulling direction that is parallel to the axial center (A) of the crucible 11 and coincides with the axial center is provided outside the bottom surface, which is the cylindrical outer surface of the lower end portion 11a. 11b is arranged. In the figure, a form with six projections 11b is shown. In FIG. 2A, the axial section of two of the protrusions is schematically shown for ease of explanation. A protrusion end surface 11d, which is the tip of the protrusion 11b, is a flat surface perpendicular to the axis of the protrusion 11b parallel to the crucible axis. These projecting portion end surfaces 11d are provided so as to be all in the same plane. At the center of the flat surface, a through hole 11c that communicates from the inside to the outside of the crucible 11 is provided so as to pass through the axial center of the protruding portion 11b. In addition, a concave portion having a conical axial cross section with the opening of the through hole 11c as a vertex is provided on the inner surface of the lower end portion 11a. Due to the presence of the recess, all of the raw material melt in the crucible 11 is stably poured into the through hole 11c. A stepped portion 11f is provided on the outer peripheral portion of the crucible outer surface of the lower end portion 11a formed of a flat surface except for the protruding portion 11b so as to be dug down inward of the crucible from the flat surface. The step portion 11f has an effect of defining the positional relationship between the after-heater described later and the crucible 11.

  In this embodiment, when the wettability of the contact portion between the raw material melt and the raw material melt in the crucible is good, for example, a metal crucible with surface polishing and an oxide-based single Suitable for combination with raw material melt to obtain crystals. In such a combination, there is a possibility that the raw material melt spreads wet on the surface of the protrusion end face 11d of each protrusion 11b. Further, depending on the holding temperature of the raw material melt, the side wall surface of the projecting portion 11b (a plane extending in a direction perpendicular to each of the crucible lower end portion 11a surface and the projecting end surface 11d and connecting these surfaces) is also wetted. There is a possibility to go up. This wetting of the raw material melt is caused by the interfacial tension acting between the surface of the crucible 11 and the raw material melt at the temperature during the pulling operation. In the present invention, by considering the conditions described below, the shape, arrangement, and the like of the protrusions 11b are determined, thereby suppressing the effects of these wetting spread and wetting up. Note that the extent of wetting spread and wetting depends on the viscosity of the raw material melt, and the viscosity is uniquely determined by the temperature of the raw material melt. Accordingly, the conditions described below are mainly determined according to the characteristics of the raw material melt at the temperature at which the raw material melt is held during the pulling operation.

  Specifically, in this embodiment, the distance d between the adjacent portions between the adjacent protrusions 11b is set to d> 2t. Here, t is a raw material held at a specific temperature (a holding temperature of the raw material melt during the pulling operation) with respect to a flat plate made of the same material as the crucible when measuring the contact angle of the raw material melt to the crucible. This corresponds to the thickness of the liquid droplets attached to the flat plate when the melt is dropped. In the crucible 11 shown in the figure, the obtained 2t value is multiplied by a safety factor that takes into account manufacturing errors, operational deficiencies during crystal growth, and the like, and the interval d is set to 0.5 mm. Further, the amount of wetting is considered to be determined by the relationship between the interfacial tension between the raw material melt and the crucible and the gravity acting on the raw material melt. Therefore, for the step h between the protrusion end surface 11d and the lower surface of the lower end portion 11a, the interface tension actually acting between the raw material melt and the crucible at the specific temperature is γ, and the density of the raw material melt. Is set so as to satisfy the relationship of γ / ρg <h in consideration of the gravitational acceleration g. In the crucible 11 shown in the figure, the value of γ / ρg obtained is multiplied by the safety factor described above, so that the step h is a step of 3 mm. By setting these d and h so as to satisfy the above conditions, it is possible to stably pull down the plurality of raw material melts in a separated and independent state corresponding to the individual protrusions. Regarding the level difference h, it is preferable that the protrusion 11b does not affect the controllability of the temperature gradient of the raw material melt by the after heater, which will be described later. Therefore, the protrusion 11b is provided in the soaking area in the axial direction of the after heater. It is preferable that the size does not penetrate.

In the above-described embodiment, the protrusion 11b provided to satisfy the predetermined condition for the influence of the interaction based on the surface tension of the raw material melt leaked from the plurality of through-hole openings. Is suppressed by the presence of However, the interaction suppression mode is not limited to the protrusions. That is, with respect to a plurality of through-hole openings arranged on the outer surface of the crucible lower end portion 11a, a mode is provided in which a groove having a width d described above and a depth h described above is provided between adjacent openings. It is also good.
Moreover, it is preferable that all the opening parts and protrusion parts are on the same temperature conditions in the soaking | uniform-heating area | region comprised by an after heater about arrangement | positioning in the horizontal surface of the opening part and protrusion part of a through-hole. Therefore, it is preferable that the opening and the protrusion are equally arranged with respect to the axial center of the after heater, and the distance of at least twice the diameter in the cross section perpendicular to the axial direction of the single crystal to be obtained is It is preferable to dispose from the inner wall.

  In addition, embodiment mentioned above has shown the suitable thing about the combination with what is called wettability with a crucible and raw material melt. However, on the contrary, in the case of a combination with poor wettability, wetting and spreading of the raw material melt leaked from the through hole does not occur. Therefore, it is not necessary to form the protrusions or grooves that suppress the interaction of the raw material melt due to the wetting and spreading at the plurality of leakage portions as described above. Therefore, it is preferable that the opening forming surface of the through hole defined as the protrusion end surface in the previous embodiment is defined as an opening end surface in which the opening is simply formed without the protrusion. In addition, it is assumed that the end surfaces of such protrusions are all accommodated in the first plane which is the same plane, and the upper surface of the seed which is a flat surface corresponds to the first plane and faces it. It is preferable to be defined as a second flat surface that is a contact surface.

  The actual pulling operation performed using the above crucible will be described. For simplification of explanation, FIGS. 1A to 1D schematically show only the tip of the crucible and the seed shown in FIG. 2A. As shown in FIG. 1A, the present invention uses a seed 5 having a crucible-facing surface 5a (hereinafter referred to as an upper flat surface) that is flat and has an area sufficient to cover all the openings of the through holes 11c in the crucible. ing. A solid raw material 7 is inserted into the crucible 11. Although not shown, the crucible 11 is placed on the after heater and positioned with reference to the after heater. From this state, the seed 5 is raised, and the upper flat surface 5a of the seed 5 is brought into contact with the protrusion end surface 11d. From this state, the seed 5 is further raised together with the crucible 11, and after confirming that the crucible 11 has moved by a predetermined amount Δl, the raising of the seed 5 is stopped (see FIG. 1B). After the raising of the seed 5 is stopped, the raw material 7 is heated and melted. A part of the raw material melt 8 generated by melting passes through each through hole 11 c and reaches the upper flat surface 5 a of the seed 5.

  The flat surface 5a on the seed is maintained at a meniscus generation temperature by an after heater or the like, and forms a meniscus at the contact portion as shown in FIG. 1C. From this state, the seed 5 starts to be pulled down at a speed at which the meniscus is stably formed at a predetermined position. By performing the above steps, a single crystal 9 having a predetermined shape is obtained from each through hole 11c as shown in FIG. 1D. Usually, the plurality of protrusion end faces 11d are processed so as to exist in the same plane, and the apparatus structure itself is designed so that the seed upper flat face 5a also faces the protrusion end face 11d. However, as described above, due to a problem with the accuracy of attaching the crucible 11 to the apparatus body, a minute gap that cannot be visually discerned is formed between the protrusion end surface 11d and the flat surface 5a on the seed. There is a risk. When the set temperature is raised so that the raw material melt 8 can easily reach the seed 5 to reduce the viscosity, it may be difficult to generate a meniscus. Therefore, the temperature of the raw material melt 8 needs to be maintained in a state where the viscosity of the raw material melt 8 is increased to some extent. However, in this case, it may happen that the raw material melt 8 passing through each through-hole 11 c cannot reach the seed 5 suitably due to the presence of the above-described gap. In addition, if it is attempted to achieve a suitable contact between the raw material melt 8 and the seed 5 by securing a sufficient time, the seed 5 itself may be melted.

  As in the present invention, by pushing up the crucible 11 by a predetermined amount, the raw material melt 8 passes through the through-hole 11c in a state where all the projecting portion end surfaces 11d are preferably in contact with the flat surface 5a on the seed. It becomes possible. As described above, the predetermined amount that rises is preferably set to at least the thickness according to the thickness of the meniscus. Further, the reproducibility of the positional relationship becomes higher when the amount of ascent is increased to some extent, but the position of the crucible 11 and the after heater is due to the presence of the crucible step portion 11f provided in the crucible 11 when the crucible 11 is returned to its original state. It is preferable that the relationship be determined so that the initial state can be reliably restored. In the present embodiment, the meniscus thickness is about 0.1 mm and the step is 0.5 mm, so the predetermined amount of increase is set to 1.0 mm.

  Next, a specific configuration of a pulling apparatus that is suitable for the single crystal pulling method described above will be described. FIG. 3 shows a configuration of the main part of the pulling apparatus along the crystal pulling direction of the apparatus. The pulling device 1 mainly includes a seed 5, a crucible 11, an after heater 13, a work coil 17, a crucible stage 19, an outer tube 25, a seed holder 31, a seed drive mechanism 33, a CCD camera 35, and a rise detection unit 37. And a control device 39. The pulling device 1 heats and melts the material by high frequency induction. The high-frequency magnetic flux is transmitted to a heating source or the like through a work coil 17 in which a metal tube capable of conducting cooling water or the like is formed in a coil shape having a predetermined inner diameter. More specifically, the work coil 17 is capable of conducting a high-frequency current, generates a high-frequency magnetic field by flowing the high-frequency current, and heats a conductive object disposed therein by induction heating with the high-frequency magnetic field. To do. The crucible 11 in which the raw material is held and melted has a cylindrical shape with the bottom surface (lower end surface) closed, and is made of carbon or a refractory metal (for example, Re, Ir, W, Ta, Mo, Pt, or These alloys). Since the specific shape of the crucible 11 has already been described in detail, the description thereof is omitted here. The crucible 11 is coaxial with the work coil 17 and is disposed at a central portion in the longitudinal direction of the work coil 17.

  In the present embodiment, the crystal pulling direction coincides with the extending direction of the axis (A) of the crucible 11 or the like. Below the crucible 11, a cylindrical after-heater 13 that contacts the vicinity of the outer periphery of the lower end of the crucible 11 and supports the crucible 11 is disposed. The after heater 13 is made of the same material as that of the crucible and is arranged so as to be coaxial with the crucible 11. When the raw material is heated, the after-heater 13 also generates heat by high-frequency induction, and the raw material melt that leaks from the lower end of the crucible 11 can be heated. Further, the length of the after heater 13 is such that when the crucible 11 disposed in the central portion in the longitudinal direction of the work coil 17 and the after heater 13 are disposed in contact with each other, the effective heating area in the work coil 17 is reduced. The after heater 13 is set to be accommodated. By installing the after heater 13, the soaking area in the pulling-down direction can be expanded, and the conditions for crystal growth can be made wider. In the present embodiment, the after heater 13 is supported at the lower end by the upper surface of the annular crucible stage 19. The crucible stage 19 is made of a material having insulation properties against high-frequency induction used for heating, such as ceramics and quartz.

  The crucible stage 21 is supported on the lower surface by an upper end portion of a cylindrical outer tube 25 made of the same material as the stage 21. The crucible 11, the after heater 13, the crucible stage 21 and the outer tube 25 are arranged so as to be coaxial, and the crystal pulling operation is performed along the axis. The seed 5 is held by the upper end portion of the seed holder 31, and the rod-like seed holder 31 is connected to the seed drive mechanism 33 at the lower end thereof. The seed 5 is movable up and down in accordance with the vertical movement of the seed holder 31 in the axial direction by the seed drive mechanism 33. In the conventional configuration, the upper end portion of the upper and lower movement range of the seed 5 by the seed drive mechanism 33 is set at a position where the seed 5 contacts the lower end surface of the crucible 11. However, in the present invention, as described above, after the contact, the movement range is extended so that the crucible 11 can be pushed up by a predetermined amount.

  The CCD camera 35 is used for observing the state of meniscus formation. The after heater 13 is provided with a through window for meniscus observation, and the CCD camera 35 can capture an image of the meniscus formation region through the through window. The rise detection unit 37 is configured by a proximity sensor that detects a push-up position when the seed 5 pushes up the crucible 11. The rise detection unit 37 generates a signal related to the amount of pushing up of the crucible 11 or the stop position in the control device 39 and sends the signal to the control device 39. The control device 39 controls the seed driving device 33 in accordance with the signal, and performs operations such as decelerating, stopping, or changing to a descending operation of the seed 5. An image obtained from the CCD camera 35 is also transmitted to the control device 39, the state of the meniscus is determined based on the obtained image, and the pulling speed of the seed 5 is controlled.

  By using the pulling device having the configuration described as one embodiment above, it is possible to suitably perform pulling and growing of a plurality of single crystals using a crucible that supplies a raw material melt from a plurality of openings. Become. That is, contact with a plurality of openings of a seed having a flat upper end surface-pushing up a predetermined amount, melting of the raw material melt in the pushed-up state, leakage of the raw material melt from the plurality of openings-seed touch, each opening It is possible to easily and reliably carry out the steps of forming a meniscus in the section, returning the crucible to a predetermined position on the after heater by lowering the seed, and simultaneously growing a plurality of single crystals by lowering the seed at a predetermined speed. . In particular, when the crucible is pushed up by the seed, it is difficult to confirm the push-up of a predetermined amount by the seed drive mechanism 33 because the push-up state may change depending on the initial position of the crucible. In the present invention, by detecting the actual push-up amount or push-up state from the behavior on the crucible side, in actuality, a minute push-up amount of 0 to 1.0 mm level is surely controlled, and each of the openings and the flat top end surface of the seed are formed. It is possible to ensure a reliable contact state.

  The basic configuration described above is an example, and various modifications can be made according to the raw materials, for example. Specifically, a cylindrical member made of a conductive material serving as a further heating element may be disposed between the crucible 11 and the work coil 17. The crucible 11 itself may not be configured to generate heat, and the cylindrical member may be configured to generate heat. Alternatively, the structure may be such that the after heater is eliminated, the after heater has a double structure, or the positional relationship between the after heater and the work coil can be modified. In the present invention, a configuration for detecting the amount of pushing up the crucible is essential, and the embodiment described above is characterized in that the proximity sensor is arranged in the direction of pushing up the crucible. However, the method of detecting the amount of push-up is not limited to the above-mentioned style.For example, by enlarging the field of view of the CCD camera for meniscus observation or by causing the CCD camera to move up and down in the axial direction, It is good also as a structure which detects the amount of pushing up. Therefore, it is preferable to grasp these configurations as configurations including various forms as the crucible vertical position detecting means.

  In addition, in embodiment mentioned above, it does not mention in particular about components other than the structure shown in figure. However, depending on the crystals to be obtained, it may be necessary to reduce the partial pressure of oxygen in the atmosphere or to create an atmospheric environment made of a specific gas. It is preferable to arrange | position in the inside of the airtight space in which etc. are possible. Further, in the present embodiment, each configuration is formed of a cylindrical shape or an annular shape, but the present invention is not limited to these shapes, and as described above, the shape of the cross section (end face) perpendicular to the pulling direction is used. Various modifications can be made according to the outer shape of the fiber-like single crystal to be obtained. In this case, when the respective components are arranged so as to be all concentric with respect to a predetermined axis parallel to the pulling-down direction, the interval formed between the respective components may be kept substantially constant.

  As described above, according to the present invention, in the manufacturing process for simultaneously growing a plurality of single crystals, a suitable and stable seed touch can be achieved with respect to the plurality of through holes provided in the crucible for the plurality of single crystals. Can be done. Accordingly, a plurality of single crystals can be simultaneously produced with good reproducibility.

DESCRIPTION OF SYMBOLS 1: Pulling-down apparatus, 5: Seed, 7: Raw material, 8: Raw material melt, 9: Single crystal, 11: Crucible, 11a: Crucible lower end part, 11b: Crucible protrusion part, 11c: Crucible through-hole, 11d: Protrusion part End face, 11f: Crucible step, 13: After heater, 17: Work coil, 19: Crucible stage, 25: Outer tube, 31: Seed holder, 33: Seed drive mechanism, 35: CCD camera, 37: Ascending detector 39: Control device

Claims (7)

Leaked from each of the through holes of the crucible having a main body part capable of holding the raw material and the raw material melt therein and a plurality of through holes communicating with the inside of the main body part and capable of leaking the raw material melt. A single crystal pulling method in which a plurality of single crystals are obtained by bringing the raw material melt into contact with a seed that determines a crystal orientation when the raw material melt is crystallized, and pulling down the seed along a predetermined pulling axis. There,
The raw material is loaded into the inside of the crucible,
The seed is brought into contact with an opening end surface where the through hole is opened, and the crucible is pushed up by a predetermined amount along the pulling shaft,
Melting the raw materials,
Contacting the seed melt with the raw material melt obtained by melting the raw material leaking from the openings of the plurality of through holes provided in the crucible;
A method of pulling down a single crystal, wherein the seed is pulled down in the pulling direction to grow a plurality of the single crystals.   The planes through which the plurality of through holes open are in the same first plane, and the seed has a second plane opposite to the first plane as a contact surface with the through holes. The method for pulling down a single crystal according to claim 1.   3. The pulling-down method according to claim 1, wherein each of the plurality of through holes is disposed on a protruding portion that independently protrudes from the main body portion in the pulling-down direction. Leaked from each of the through holes of the crucible having a main body part capable of holding the raw material and the raw material melt therein and a plurality of through holes communicating with the inside of the main body part and capable of leaking the raw material melt. A single crystal pulling device that contacts a seed that determines a crystal orientation when the raw material melt crystallizes into the raw material melt, and pulls the seed along a predetermined pulling axis to obtain a plurality of single crystals. There,
A work coil that is wound around the crucible and is capable of conducting high-frequency current and can generate a high-frequency magnetic field by the high-frequency current;
A seed holder for holding a seed for determining a crystal orientation when the raw material melt is crystallized;
A seed drive mechanism for driving the seed holder up and down along the pull-down shaft;
And a crucible vertical position detecting means for detecting a push-up amount when the seed pushes up the crucible by a predetermined amount by the seed drive mechanism.   The planes through which the plurality of through holes open are in the same first plane, and the seed has a second plane opposite to the first plane as a contact surface with the through holes. The apparatus for pulling down a single crystal according to claim 4.   The pulling device according to claim 4, wherein each of the plurality of through holes is disposed on a protruding portion that protrudes independently from the main body portion in the pulling direction.   A groove having a width and a depth for preventing interaction of the raw material melt leaking from the adjacent through hole is formed in an outer surface of the crucible where the through hole is formed. The pulling-down device according to claim 4 or 5.

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