Apparatus for manufacturing thin plate-shaped single crystal and method for manufacturing thin plate-shaped single crystal

Abstract

This invention provides a single crystal thin-plate manufacturing apparatus and a single crystal thin-plate manufacturing method. Even if there are other blending and melting substances besides the single crystal of decomposed melting substances or solid solution substances, it is possible to manufacture thin-plate single crystals with the optimal additive concentration and homogeneity and a thickness of about several hundred μm at low cost and with high precision. The present invention comprises: an infrared irradiation unit for irradiating the upper side surface of a raw material block for manufacturing a thin plate-shaped single crystal with infrared rays, thereby melting the surface of the upper side surface; and a lifting unit for immersing the lower side surface of a thin plate-shaped single crystal seed in the molten liquid obtained from the surface of the upper side surface by the infrared irradiation unit, and lifting the thin plate-shaped single crystal seed upward from the immersed state. The invention is configured such that: the lower side surface of the thin plate-shaped single crystal seed is immersed in the molten liquid obtained from the surface of the upper side surface of the raw material block for manufacturing a thin plate-shaped single crystal by the infrared irradiation unit through the lifting unit, thereby growing a single crystal from the lower side surface of the immersed thin plate-shaped single crystal seed, and the thin plate-shaped single crystal seed is lifted upward through the lifting unit, thereby continuously manufacturing thin plate-shaped single crystals.

Description

Technical Field

[0001] This invention relates to an apparatus and method for continuously manufacturing thin-plate single crystals with a thickness of several hundred μm. Prior Technology

[0002] In recent years, we have been calling for a shift from fossil fuels to renewable energy, and to promote a global-scale transition from oil-consuming power generation to solar power generation using solar cells that utilize sunlight. However, the cost of solar power generation is still relatively high compared to other power generation methods, and there is a need to develop highly efficient and inexpensive solar cells.

[0003] Various substrate materials are known to constitute solar cells, including semiconductor silicon crystal, amorphous silicon, and compound semiconductor silicon crystal, and each is being developed separately. Among them, semiconductor silicon crystal is the main substrate material. The general size of the substrate is 155mm square and about 0.3mm thick. A product made by processing this general-sized silicon crystal substrate to generate electricity efficiently from sunlight and installing electrodes to extract the generated electricity is called a "cell". A product in which multiple cells are arranged in a planar shape is called a "module". The module is set up according to the usage environment and used as a solar power generation device.

[0004] To reduce the cost of solar cell power generation, it is important to improve the performance of the main component of the cell, namely the substrate made of semiconductor silicon crystal, and to develop novel manufacturing methods that can reduce the manufacturing cost of the substrate material by less than the current level.

[0005] However, regarding the construction of solar cell units that are considered to achieve high-efficiency power generation, there is a method called HIT (Heterojunction with Intrinsic Thin-layer) that involves sandwiching an N-type silicon monocrystalline plate with phosphorus added from both sides with an amorphous silicon layer, thereby expanding the wavelength range of usable sunlight.

[0006] The highest efficiency is achieved by using a method known as the HIT type, where all electrodes for extracting generated electricity are concentrated on the back side, and a combination of back contacts (or back electrodes) is used to eliminate electrodes on the surface. In the N-type silicon single-crystal substrate used here, phosphorus must be added homogeneously in an optimal composition.

[0007] There are currently two main methods for manufacturing silicon crystalline substrates for general-purpose solar cells. The first method is a unidirectional solidification method in which the raw materials are melted in a large quartz crucible and solidified from bottom to top. The resulting large crystalline blocks are then cut into universal sizes to manufacture crystalline substrates.

[0008] However, the crystal blocks produced by this method are boron-added P-type polycrystalline materials, and in principle, this unidirectional solidification method cannot manufacture the N-type monocrystalline substrate necessary for the aforementioned high-efficiency solar cells.

[0009] The second method involves melting the raw material in a quartz crucible, impregnating the resulting melt with a single crystal seed, widening it while pulling it upwards—a process known as the pulling method—to produce a cylindrical single crystal. The produced cylindrical single crystal is then cut and processed to manufacture a single crystal substrate of a universal size.

[0010] This method of increasing production cost has two major problems. The first problem is that it will increase the unit cost of manufacturing. The manufacturing cost of single crystal rods obtained by the pulling method increases with the diameter of the single crystal rod. To obtain a substrate of a universal size, a single crystal rod with a diameter of about 250 mm is required, but to reduce manufacturing costs, a single crystal rod with a diameter of about 200 mm is used to manufacture a substrate of a universal size. As a result, the four corners of the resulting substrate have imperfections, and the efficiency is naturally lower compared to a finished product with a correctly shaped quadrilateral.

[0011] The second challenge of the stretching method is that the concentration of phosphorus added to achieve N-type crystal formation cannot be homogenized. While the phosphorus concentration in the melt from the silicon raw material is homogeneous, the concentration in the initial solidification phase of the single crystal becomes lower than that in the melt. This phenomenon is called "partitioning," and the ratio of phosphorus concentration in the melt to that in the solidified product is called the "partition coefficient."

[0012] In the case of silicon, the partition coefficient of phosphorus is approximately 0.35, so the phosphorus concentration in the initially solidified portion will remain in the melt with slight variations. Therefore, as solidification progresses, the phosphorus concentration in the melt will increase, and consequently, the phosphorus concentration in the solidified product will also increase due to the partition coefficient. Thus, the optimal composition is limited to a portion of the resulting single crystal.

[0013] Furthermore, during the initial solidification stage of the raw material melted in the crucible, about half of it becomes too concentrated, making it unusable for solar cell applications. Therefore, the following manufacturing method is adopted: the single crystal manufacturing process is stopped, the gas environment inside the manufacturing furnace is maintained in an inactive gas environment, the product is removed while maintaining the temperature of the raw material melt, new granular raw material is added to the remaining raw material melt to restore the original raw material melt composition, and then the second single crystal is manufactured.

[0014] Because this manufacturing method consumes the quartz crucible used to preserve the molten raw material, it can only be reused twice, or at most three times when using a specially formulated high-quality quartz crucible.

[0015] The most problematic aspect of this manufacturing method is that the phosphorus concentration in the finished product cannot be homogeneous. Although it can efficiently produce solar cells with only the optimal composition, the low yield of the optimal composition leads to higher prices and directly increases the cost of power generation.

[0016] Therefore, if a lower or higher phosphorus concentration is used in an attempt to reduce costs compared to the optimal composition, the power generation efficiency of the module will inevitably deteriorate. In addition to the above, efforts have been made to develop other methods to reduce the manufacturing cost of silicon monocrystalline substrates for solar cells. Of course, compared to cutting large crystal blocks to manufacture thin monocrystalline sheets, manufacturing thin monocrystalline sheets of a predetermined thickness from the beginning and cutting them into predetermined sizes can reduce cutting losses and production costs more easily.

[0017] To date, three methods have been reported for manufacturing silicon sheet-like crystals. The first method involves inserting a jig (also known as a die) with a slit into the molten raw material melted in a crucible. A thin plate-shaped single crystal seed is immersed in the molten raw material melt that comes out from the top of the die through the slit of the die (DIE) by surface tension. While the seed solidifies, it is pulled upward to produce a thin plate-shaped single crystal. This method is called the EFG (Edge Defined Film-fed Growth) method.

[0018] This manufacturing method has been developed primarily in the United States, but it has not yet been commercialized for use in manufacturing silicon substrates for solar cells. Reasons for this include the lack of suitable materials for auxiliary equipment that can withstand stable, long-term use, difficulties in temperature control during the solidification of the molten raw material, and challenges in large-scale production.

[0019] The second method is called the ESR (Edge Stabilized Ribbon) method, which uses a thin rope instead of the aforementioned die casting (DIE) method. In the ESR method, the thin rope is first immersed in the surface of the molten raw material and brought closer to it in the lateral direction. When it is lifted slightly, the molten raw material attached to the rope and lifted upwards will solidify into a thin plate-like crystal due to surface tension.

[0020] If you tie a thin string to both ends of a string and pull them upwards together, the solidified thin-plate crystals will also grow and be pulled upwards at the same time. However, the part that is initially pulled up and solidified by the string is "polycrystalline", and the thin plate that grows along with it is also "polycrystalline" and will not become "monocrystalline".

[0021] The third method is named the dendritic web growth method. Dendrites have the property that, when their growth rate reaches a certain level, they preferentially grow in directions with higher thermal conductivity. This method utilizes this property of dendrites to manufacture thin, sheet-like crystals.

[0022] This method does not use auxiliary tools or strings like the EEG or ESR methods, and single crystals can still be grown if the growth is controlled appropriately. However, since single crystals cannot be manufactured in reality without ensuring that the initial dendrite is singular, there are no examples of continuously growing large, long, thin, plate-like single crystals using this method, and industrial production is not yet possible.

[0023] On the other hand, as mentioned above, all reported methods for manufacturing thin-plate crystals to date involve storing molten silicon in a quartz crucible to produce crystals. In these methods, if the raw silicon is melted in the quartz crucible, the molten silicon will react with the quartz as shown in Formula 1 to produce silicon monoxide (SiO).

[0024]

[0025] The silicon monoxide (SiO) generated during the reaction can be incorporated into the silicon crystals of the finished product as a solid solution, becoming a major cause of performance degradation in single crystals. Therefore, a manufacturing method that does not require the use of a quartz crucible is desired for producing high-quality single crystals.

[0026] Currently, among methods for manufacturing silicon single crystals without using a crucible, the high-frequency floating-area melting method, which uses high-frequency induction heating to melt and solidify the raw material rod to manufacture single crystals, has been put into practical use (e.g., Patent Document 1). This high-frequency floating-area melting method can produce high-purity single crystals that do not contain silicon monoxide (SiO).

[0027] However, the raw material rods used in the high-frequency floating-area melting method are specially formulated high-density products. Such raw material rods are not only expensive but also have limited supply, making them unsuitable for applications requiring low-cost solar cells. Moreover, the high-frequency floating-area melting method is extremely difficult to use in the fabrication of thin-plate single crystals, and there are no reports of its fabrication.

[0028] Another method for manufacturing high-purity single crystals without using a crucible is known to utilize infrared radiation. Among the methods for manufacturing single crystals using infrared radiation is the infrared floating-field melting method, which involves processing raw material powder into rod shapes and locally heating them to melt and solidify them to produce single crystal rods.

[0029] This infrared floating melting method allows the molten material formed by infrared heating to be retained in the raw material rod by the surface tension of the molten material itself, so that the melting and solidification of the raw material can continue. Furthermore, this infrared floating-field melting method previously employed a method of irradiating infrared light from a horizontal direction. However, this horizontal irradiation method is theoretically unable to produce large-diameter single crystals.

[0030] Therefore, a top-melting method has been developed that involves irradiating the top of a large-diameter single crystal seed placed below with infrared light to melt it, and then adding a melted raw material solution to dissolve the seed material, thereby producing a large-diameter single crystal. In principle, there is no limit to the diameter of the single crystal that can be produced using this top-melting method, thus significantly expanding its applicability.

[0031] On the other hand, as for the single crystal materials currently used in industry, in addition to the materials used in solar cells mentioned above, most oxide materials are also used, such as lithium niobate or lithium tantalate, which are strong dielectric materials; argonium silicate or thionium silicate, which are phosphor materials; and yttrium aluminum garnet or thionium gallium garnet, which are laser materials.

[0032] These oxide materials are used to manufacture rod-shaped single crystals by the pulling method, and the rings are cut and processed into thin plate-shaped single crystals with a thickness of about 0.3 mm, and are used in the manufacture of various devices. However, the pulling method cannot avoid contamination from the crucible material in the product, and due to the aforementioned segregation phenomenon, in principle, it is impossible to homogenize the concentration in the product of useful additives. Therefore, it is inconvenient in the manufacture of high-quality devices.

[0033] Therefore, compared with manufacturing rod-shaped single crystals and then cutting and processing them into thin plate-shaped single crystals for reuse, those that manufacture thin plate-shaped single crystals with a predetermined thickness with the optimum composition from the beginning can manufacture high-performance products at a lower cost. [Prior Art Documents] [Patent Documents]

[0034] [Patent Document 1] Japanese Patent No. 5279727 Summary of the Invention Problems to be Solved by the Invention

[0035] However, the research and development results in the methods for manufacturing thin plate-shaped single crystals so far are not sufficient, and the only examples known of manufacturing thin plate-shaped single crystals and using them in industry are up to the extent of manufacturing sapphire single crystal plates or gallium oxide single crystal plates by the EFG method.

[0036] In view of such circumstances, the object of the present invention is to provide a device for manufacturing thin plate-shaped single crystals and a method for manufacturing thin plate-shaped single crystals, which can manufacture thin plate-shaped single crystals with an optimum composition and homogeneous additive concentration and a thickness of about several hundred μm at low cost and with continuous high precision. Means for Solving the Problems

[0037] The present invention is an invention for solving the problems in the aforementioned prior art. The thin plate-shaped single crystal manufacturing device of the present invention is characterized by including the following units: An infrared irradiation unit that irradiates infrared rays on the upper surface of a raw material mass for manufacturing thin plate-shaped single crystals (hereinafter, also referred to as a raw material mass) to melt the surface of the aforementioned upper surface; and A lifting unit that immerses the lower surface of a thin plate-shaped single crystal seed in the melt obtained on the surface of the aforementioned upper surface melted by the aforementioned infrared irradiation unit, and pulls the aforementioned thin plate-shaped single crystal seed upward from the immersed state; Furthermore, the thin-plate single crystal manufacturing apparatus is configured such that: the lower side of the thin-plate single crystal seed is immersed in the molten liquid obtained on the surface of the upper side of the raw material block for manufacturing the thin-plate single crystal by means of the aforementioned lifting unit, thereby growing a single crystal from the lower side of the immersed thin-plate single crystal seed, and the thin-plate single crystal seed is pulled upward by means of the aforementioned lifting unit, thereby continuously manufacturing thin-plate single crystals.

[0038] With such a configuration, the device requires fewer components and can manufacture thin, plate-shaped single crystals with an optimal additive concentration and homogeneity, and a thickness of approximately several hundred μm, at low cost and with continuous high precision. Furthermore, it can manufacture thin, plate-shaped single crystals with homogeneous compositions of so-called inconsistently dissolved substances, such as decomposed molten substances or solid solution substances, with high precision.

[0039] Furthermore, the thin-plate single-crystal manufacturing apparatus of the present invention is characterized in that... The infrared light irradiated by the aforementioned infrared irradiation unit is laser light. If such a laser light is used, the molten metal will not overflow from the upper side of the raw material block because it can be heated correctly within a predetermined range, and the molten metal (molten metal retention pool) can be formed continuously and reliably.

[0040] Furthermore, the thin-plate single-crystal manufacturing apparatus of the present invention is characterized in that... The irradiated area of ​​the aforementioned laser light is a slender, hollow quadrilateral shape in the horizontal direction. The peripheral area of ​​the upper side surface of the aforementioned thin plate-shaped single crystal manufacturing raw material block, excluding the center, is irradiated with laser light in a manner that forms the aforementioned hollow quadrilateral irradiation area.

[0041] If the laser light is applied to the peripheral area of ​​the upper side of the raw material block, excluding the center, in a matching manner to form such a hollow quadrilateral irradiation area, the peripheral area of ​​the upper side of the raw material block, excluding the center, will melt first, while the center, which has not been irradiated by laser light, will melt due to heat conduction from the melted peripheral area.

[0042] Therefore, the temperature in the center can be controlled to be lower than that in the peripheral area. Additionally, a method for forming a hollow, quadrilateral irradiation area using laser light can be employed, for example, by irradiating a straight line of laser light from all four sides.

[0043] Furthermore, for the upper side of the raw material block, the laser light can be irradiated from an obliquely upward direction or from a vertical direction directly above, but it is preferable to adjust the irradiation angle to the optimal angle according to the thermal conductivity characteristics of the single crystal material and the thickness of the thin plate-shaped single crystal to be manufactured. Furthermore, to continuously manufacture thin-plate single crystals by melting raw material blocks, the melting of the raw material blocks and the solidification of the thin-plate single crystals must occur simultaneously. However, the melting of the raw material blocks requires heating, while the solidification of the thin-plate single crystals requires cooling of the melt.

[0044] Therefore, in order to stably manufacture thin plate-shaped single crystals, it is necessary to continuously and steadily perform the opposite actions of "heating" and "cooling" with good control. This can be achieved by irradiating the raw material block with the aforementioned hollow quadrilateral laser light. In other words, by creating such a temperature distribution in the molten pool on the upper side of the raw material block, the growth of thin plate-shaped single crystals can be stably and continuously carried out from the center.

[0045] Furthermore, the thin-plate single-crystal manufacturing apparatus of the present invention is characterized in that... The aforementioned lifting unit is a winding unit that continuously winds the manufactured thin-plate single crystal into a roll shape. The aforementioned winding unit includes: a winding shaft for continuously winding the aforementioned thin plate-shaped single crystal, and The rotating unit that causes the aforementioned roll shaft to rotate, The thin-plate single crystal manufacturing apparatus is configured such that the aforementioned thin-plate single crystal seed is suspended from the aforementioned roll shaft.

[0046] With such a winding unit, continuously manufactured thin-plate single crystals can be reliably wound onto a roll without making the equipment excessively large. Furthermore, since the manufactured thin-plate single crystals are in a roll shape, they can be easily transported during shipment, improving operability.

[0047] Furthermore, the thin-plate single-crystal manufacturing apparatus of the present invention is characterized in that... The aforementioned thin plate-shaped single crystal seed system is suspended from the aforementioned roll shaft by multiple fine threads. By using heat-resistant and high-strength fine wires to suspend thin plate-shaped single crystal seeds, the continuously manufactured thin plate-shaped single crystals can be reliably wound onto a roll.

[0048] Furthermore, in the thin-plate single-crystal manufacturing apparatus of the present invention, it is preferred to be In the aforementioned thin-plate-shaped single crystal seed, The thickness of the portion on which the aforementioned fine wires are installed is less than or equal to the thickness required to manufacture the aforementioned thin plate-shaped single crystal.

[0049] In this way, if the thickness of the portion where the fine wire is installed in the thin plate-shaped single crystal is set to be less than or equal to the thickness of the thin plate-shaped single crystal to be manufactured, then when the thin plate-shaped single crystal is wound onto the roll spool, it can reliably prevent the surface of the thin plate-shaped single crystal from coming into contact with the fine wire and causing damage.

[0050] Furthermore, the thin-plate single-crystal manufacturing apparatus of the present invention is characterized in that... On the upper side of the aforementioned thin-plate-shaped raw material block for manufacturing single crystals, Initially, a liquid phase composition is prepared in the necessary amount to coexist in equilibrium with the composition of the aforementioned thin plate-shaped single crystal to be manufactured.

[0051] In this way, if a liquid phase composition that is in equilibrium with the composition of the thin plate-shaped single crystal to be manufactured is initially arranged on the upper side of the raw material block in the necessary amount, then a homogeneous thin plate-shaped single crystal with the optimal composition can be continuously manufactured.

[0052] Furthermore, the thin-plate single-crystal manufacturing apparatus of the present invention is characterized in that... Between the aforementioned lifting unit and the aforementioned thin-plate-shaped raw material block for manufacturing single crystals It is equipped with an anti-vibration component to prevent vibration of the aforementioned thin plate-shaped single crystal that is to be continuously manufactured.

[0053] With such anti-vibration components, excessive lateral vibration of the manufactured thin-plate single crystal can be suppressed. Therefore, the growth position will not deviate excessively and can be kept within the predetermined range, enabling the continuous and stable manufacture of high-quality thin-plate single crystals.

[0054] Furthermore, the thin-plate single crystal manufacturing apparatus of the present invention is preferably, Between the aforementioned lifting unit and the aforementioned thin-plate-shaped raw material block for manufacturing single crystals A shielding member is provided to shield the radiant heat emitted from the aforementioned molten liquid from being transmitted to the aforementioned thin plate-shaped single crystal that has been continuously manufactured.

[0055] Thin-plate single crystals are drawn from the molten liquid and gradually solidify. However, when the radiative heat emitted from the molten liquid is conducted to the manufactured thin-plate single crystal, the manufacturing speed of the thin-plate single crystal becomes difficult to accelerate. Therefore, by incorporating a shielding component, the radiative heat of the molten liquid becomes difficult to transfer to the manufactured thin-plate single crystal, thereby improving the manufacturing efficiency of the thin-plate single crystal.

[0056] Furthermore, the thin-plate single-crystal manufacturing apparatus of the present invention is characterized in that... The aforementioned raw material block for manufacturing thin plate-shaped single crystals is a slightly rectangular cuboid. With such a shape, molten liquid (molten liquid retention pool) can be continuously provided on the upper surface of the raw material block by irradiating it with infrared light.

[0057] Furthermore, the thin-plate single-crystal manufacturing apparatus of the present invention is characterized in that... Compared to the size of the lower side of the aforementioned thin plate-shaped single crystal seed, the size of the upper side of the aforementioned raw material block for manufacturing thin plate-shaped single crystal is set to be several millimeters larger in both the thickness direction and the transverse direction.

[0058] If the size of the raw material block and the thin plate-shaped single crystal seed is set in this way, the lower side of the thin plate-shaped single crystal seed can be completely immersed in the melt, and thin plate-shaped single crystals of the desired size can be continuously manufactured.

[0059] Furthermore, the thin-plate single crystal manufacturing apparatus of the present invention is characterized by comprising: The mounting stage is for holding the aforementioned thin-plate-shaped raw material block used in the manufacture of single crystals. The position control unit controls the position of the aforementioned platform in a manner that makes the position of the platform a predetermined position.

[0060] If the position of the stage (especially the vertical position) can be controlled in this way, even if the liquid level of the molten raw material decreases as the thin plate-shaped single crystal is pulled up, the position of the raw material can still be pulled up in a way that maintains its original position, and the liquid level can always be controlled at the same position. Therefore, as long as the infrared irradiation position can be kept fixed at the same position, thin plate-shaped single crystals can be manufactured stably and continuously with good yield. In addition, when a parallel laser beam is irradiated onto the upper side of the raw material block from a vertical direction, the irradiation intensity of the laser beam will not change even if the liquid surface position of the molten raw material block drops. Therefore, it is not necessary to maintain the liquid surface position of the molten raw material block at a constant level for position control.

[0061] Furthermore, the thin-plate single-crystal manufacturing apparatus of the present invention is characterized in that... The aforementioned lifting unit system is configured as follows: The lower side of the aforementioned thin plate-shaped single crystal seed is immersed in the center of the molten material on the upper side of the raw material block for manufacturing the thin plate-shaped single crystal, which is melted by the aforementioned infrared irradiation unit.

[0062] The center of the molten liquid is the part where the molten liquid is continuously retained. If the lower side of the thin plate-shaped single crystal seed is immersed in the center, the thin plate-shaped single crystal seed can be continuously manufactured by pulling it upward with a lifting unit.

[0063] Furthermore, the thin-plate single-crystal manufacturing apparatus of the present invention is characterized in that... Around the aforementioned thin-plate-shaped raw material block for manufacturing single crystals, A preheating unit is provided to preheat the aforementioned raw material block for manufacturing thin plate-shaped single crystals.

[0064] By preheating the raw material block to near its melting point, the amount of infrared radiation irradiated by the infrared irradiation unit can be reduced, while the adjustment accuracy can be improved, allowing for fine-tuning of the range of the molten pool. Therefore, thin-plate single crystals can be manufactured stably and with high precision continuously.

[0065] Furthermore, the thin-plate single crystal manufacturing apparatus of the present invention is preferably, The chamber is equipped with at least the aforementioned thin-plate-shaped raw material block for manufacturing single crystals. The aforementioned lifting unit is provided at the upper part of the aforementioned chamber. If the raw material block is arranged in this way in the chamber, thin plate-shaped single crystals can be manufactured in a gas environment that matches the single crystal material.

[0066] Furthermore, the thin-plate single-crystal manufacturing apparatus of the present invention is characterized in that... It is equipped with a gas introduction device, which fills the aforementioned chamber with ambient gas containing additives.

[0067] With such a gas introduction device, the chamber can be made into a gas environment that matches the characteristics of the material to be manufactured as a thin plate-shaped single crystal. In this way, high-quality thin plate-shaped single crystals with the optimal additive concentration and homogeneity can be manufactured.

[0068] Furthermore, the thin-plate single-crystal manufacturing apparatus of the present invention is characterized in that... A plurality of the aforementioned lifting units are provided on the upper part of the aforementioned thin plate-shaped raw material block for manufacturing single crystals.

[0069] With such a configuration, for example, multiple thin-plate single crystal seeds can be immersed side by side in a molten pool and each can be pulled up to the top by a lifting unit. In this way, the manufacturing efficiency of thin-plate single crystals can be improved compared with the case of a single lifting unit.

[0070] Furthermore, in the thin-plate single-crystal manufacturing apparatus of the present invention, The thickness of the aforementioned thin plate-shaped single crystal seed is preferably in the range of 300 μm to 500 μm. With such a thickness, high-purity thin-plate single crystals can be continuously manufactured and rolled up, thereby achieving elongation.

[0071] Furthermore, in the thin-plate single-crystal manufacturing apparatus of the present invention, The thickness of the aforementioned thin plate-shaped single crystal is preferably in the range of 100 μm to 3000 μm. While the thickness of the thin plate-shaped single crystal to be manufactured can range from 100 μm to 3000 μm, it is preferable to be in the range of 100 μm to 500 μm when it is intended to be wound by a winding unit. However, it can also be adjusted to be thinner than 100 μm or thicker than 500 μm by adjusting the melt temperature and the pulling speed.

[0072] However, for thin plate-shaped single crystals thicker than 500 μm, the diameter of the single crystal when wound into the winding unit's roll shaft becomes larger. In such cases, it is also possible to produce the product by pulling it upwards without winding it. Especially when manufacturing silicon thin plate-shaped single crystals for solar cells, the thickness of the thin plate-shaped single crystal is preferably in the range of 200 μm to 400 μm.

[0073] Furthermore, the method for manufacturing thin plate-shaped single crystals of the present invention is characterized by comprising at least the following steps: The melting step involves irradiating the upper side of the raw material block for manufacturing thin-plate single crystals with infrared light through an infrared irradiation unit, thereby melting the surface of the upper side of the raw material block for manufacturing thin-plate single crystals. The growth step involves immersing the lower side of a thin-plate-shaped single crystal seed in the molten liquid obtained from the surface of the upper side of the raw material block used for manufacturing the thin-plate-shaped single crystal in the aforementioned melting step using a lifting unit, and starting the growth of the single crystal from the lower side of the thin-plate-shaped single crystal seed; and The continuous manufacturing step involves pulling the aforementioned thin-plate single crystal seed, which has begun to grow into a single crystal in the aforementioned growth step, upward to continuously manufacture the thin-plate single crystal. If such a manufacturing method is adopted, it is possible to manufacture thin plate-shaped single crystals with an optimal additive concentration, homogeneity, and a thickness of about several hundred μm at low cost and with continuous high precision.

[0074] Furthermore, the method for manufacturing thin-plate single crystals according to the present invention is characterized in that... In the aforementioned melting step, The infrared light irradiated by the aforementioned infrared irradiation unit is laser light.

[0075] If such a laser light is used, the molten metal will not overflow from the upper side of the raw material block because it can accurately heat the predetermined area of ​​the raw material block in the desired shape, and a molten metal retention pool can be reliably and continuously formed.

[0076] Furthermore, the method for manufacturing thin-plate single crystals according to the present invention is characterized in that... In the aforementioned melting step, The irradiated area of ​​the aforementioned laser light is a slender, hollow quadrilateral shape in the horizontal direction. The peripheral area of ​​the upper side surface of the aforementioned thin plate-shaped single crystal manufacturing raw material block, excluding the center, is irradiated with laser light in a manner that forms the aforementioned hollow quadrilateral irradiation area.

[0077] If the laser light is applied to the peripheral area of ​​the upper side of the raw material block, excluding the center, in a matching manner to form such a hollow quadrilateral irradiation area, the peripheral area of ​​the upper side of the raw material block, excluding the center, will melt first, while the center, which is not irradiated by the laser light, will melt due to heat conduction from the melted peripheral area.

[0078] Therefore, the temperature in the center can be controlled to be lower than that in the surrounding area. This allows for stable and well-controlled continuous melting of the raw material block and the reverse process of solidification from the molten metal. That is, by giving the molten pool on the upper side of the raw material block such a temperature distribution, the growth of thin plate-shaped single crystals can be carried out stably and continuously from the center.

[0079] Furthermore, for the upper side of the raw material block, the laser light can be irradiated from an oblique upward direction or from a vertical direction directly above. However, it is preferable to adjust the irradiation angle to the optimal angle according to the thermal conductivity and thickness of the thin plate-shaped single crystal material. For materials with high thermal conductivity, it is preferable to control the angle between the laser light irradiation angle and the horizontal direction to be larger; for materials with low thermal conductivity, it is preferable to control the angle between the laser light irradiation angle and the horizontal direction to be smaller.

[0080] Furthermore, the method for manufacturing thin-plate single crystals according to the present invention is characterized in that... Following the aforementioned continuous manufacturing steps, it further has the following characteristics: The winding step involves winding the aforementioned thin-plate single crystal, which has been continuously manufactured, into a roll shape. With such a winding step, the continuously manufactured thin sheet-like single crystal can be reliably wound into a roll shape, and thin sheet-like single crystals can be manufactured efficiently.

[0081] Furthermore, the method for manufacturing thin-plate single crystals according to the present invention is characterized in that... In the aforementioned melting step, To manufacture the aforementioned thin plate-shaped single crystal as a decomposition and melting substance, the composition of a liquid phase (also called a solvent phase) that coexists in equilibrium with the composition of the aforementioned thin plate-shaped single crystal is first arranged on the upper side of the raw material block for manufacturing the aforementioned thin plate-shaped single crystal in a necessary amount.

[0082] Furthermore, the method for manufacturing thin-plate single crystals of the present invention is characterized in that, In the aforementioned melting step, To manufacture the aforementioned thin-plate single crystal as a solid solution containing additives, the composition of a liquid phase (also called a solvent phase) that coexists in equilibrium with the composition of the aforementioned thin-plate single crystal is first prepared on the upper side of the raw material block for manufacturing the aforementioned thin-plate single crystal in a necessary amount.

[0083] Therefore, if the thin-plate single crystal solidifies from the solvent phase formed on the upper side of the raw material block from the beginning, the amount of solvent phase will decrease, and the crystalline component in the composition will become less. As a result, the intensity of laser light arrival will increase on the lower side of the solvent phase, causing the temperature to rise, and thus the raw material block will continue to melt.

[0084] In this way, since crystallization and melting of the raw material occur simultaneously, the additive concentration in the resulting product (thin plate-shaped single crystal) becomes the same as that in the raw material, thus becoming homogeneous. This process is called the "solvent migration method," and it is the only means of producing homogeneous single crystal products using the melt method.

[0085] In this way, by first configuring a liquid phase composition that is in equilibrium with the composition of the thin plate-shaped single crystal to be manufactured on the upper side of the raw material block in the necessary amount, a homogeneous thin plate-shaped single crystal with the optimal composition can be continuously manufactured.

[0086] Furthermore, the method for manufacturing thin-plate single crystals according to the present invention is characterized in that... In the aforementioned growth steps, The lower side of the aforementioned thin plate-shaped single crystal seed is immersed in the center of the molten material on the surface of the upper side of the aforementioned melted thin plate-shaped single crystal manufacturing raw material block.

[0087] The central part of the melt is the part where the melt continuously stays. If the lower surface of the thin plate-shaped single crystal seed is immersed in this central part, by lifting the thin plate-shaped single crystal seed upward with a lifting unit, a thin plate-shaped single crystal can be continuously manufactured. Effect of the Invention

[0088] According to the thin plate-shaped single crystal manufacturing apparatus and the thin plate-shaped single crystal manufacturing method of the present invention, by melting the surface of the upper side of the raw material block for manufacturing the thin plate-shaped single crystal with infrared rays to form a melt, immersing the thin plate-shaped single crystal seed in the melt and lifting it upward, it is possible to manufacture a thin plate-shaped single crystal with an additive concentration of an optimal composition, homogeneous, and a thickness of about several hundred μm at low cost and with continuous high precision. Brief Explanation of Drawings

[0089] FIG. 1 is a schematic diagram of a thin plate-shaped single crystal manufacturing apparatus in the first embodiment of the present invention. FIG. 2 is a diagram showing the shape of the irradiation area of the laser light irradiated from the infrared irradiation unit. FIG. 3 is a conceptual diagram of the state of the raw material block for manufacturing the thin plate-shaped single crystal as viewed from the upper side in the thin plate-shaped single crystal manufacturing apparatus of the present invention. FIG. 4 is another schematic diagram of a thin plate-shaped single crystal manufacturing apparatus in the first embodiment of the present invention. FIG. 5 is a diagram for explaining the state of the melt (melt retention pool) formed on the upper side of the raw material block for manufacturing the thin plate-shaped single crystal in the thin plate-shaped single crystal manufacturing apparatus shown in FIG. 1. FIG. 6 is a diagram for explaining the state of the melt (melt retention pool) formed on the upper side of the raw material block for manufacturing the thin plate-shaped single crystal in the thin plate-shaped single crystal manufacturing apparatus shown in FIG. 4. FIG. 7 is a schematic perspective view for explaining the states of the raw material block for manufacturing the thin plate-shaped single crystal, the thin plate-shaped single crystal seed, and the thin plate-shaped single crystal. FIG. 9 is a schematic diagram of a thin plate-shaped single crystal manufacturing apparatus in the second embodiment of the present invention. FIG. 10 is a schematic diagram of another thin plate-shaped single crystal manufacturing apparatus in the second embodiment of the present invention. FIG. 11 is an enlarged view of an important part of the thin plate-shaped single crystal manufacturing apparatus shown in FIG. 10. FIG. 12 is a schematic diagram showing the steps of the thin plate-shaped single crystal manufacturing method of the present invention. FIG. 13 is a schematic diagram showing the steps of the thin plate-shaped single crystal manufacturing method of the present invention. FIG. 13 is a schematic diagram showing the steps of the thin plate-shaped single crystal manufacturing method of the present invention. Implementation

[0090] The apparatus and method for manufacturing thin-plate single crystals of the present invention will be described in more detail below with reference to the drawings. The thin-plate single crystal manufacturing apparatus and method of the present invention are used to manufacture thin-plate single crystals with an optimal additive concentration, homogeneity, and a thickness of about several hundred μm at low cost and with continuous high precision.

[0091] <Thin-plate single crystal manufacturing device 10> [First Implementation Form] In the first embodiment of the present invention, the thin-plate single crystal manufacturing apparatus 10 is as shown in FIG1. ​​First, a raw material block (hereinafter also referred to as raw material block) 12 for manufacturing thin-plate single crystals is provided on a mounting stage 82 disposed below the chamber 80. The raw material block 12 is a slightly rectangular parallelepiped, for example, a plate-shaped body like a book.

[0092] Furthermore, an infrared irradiation unit 20 is provided on the upper side of the chamber 80. This infrared irradiation unit 20 irradiates infrared rays 16 onto the upper side surface 14 of the slightly rectangular raw material block 12, causing the surface of the upper side surface 14 to melt. In addition, the infrared light 16 irradiated from the infrared irradiation unit 20 is preferably laser light 16a.

[0093] That is, as shown in Figure 2, the shape of the irradiation area of ​​the laser light 16a is set to be an elongated hollow quadrilateral shape in the horizontal direction (vertical direction in Figure 2), and as shown in Figure 3, it is preferable to irradiate the peripheral area of ​​the upper side surface 14 of the raw material block 12 in a matching manner to form an irradiation area with an elongated hollow quadrilateral shape in the horizontal direction.

[0094] Here, the laser light 16a irradiated by the infrared irradiation unit 20 preferably enters the chamber 80 through the window 22 located on the side of the chamber 80, and irradiates the peripheral area of ​​the upper side surface 14 of the raw material block 12, excluding the center, through the reflector 24 inside the chamber 80. At this time, the laser light 16a can irradiate the upper side surface 14 of the raw material block 12 from an obliquely upward direction as shown in FIG1, or it can irradiate the upper side surface 14 of the raw material block 12 from a vertical direction directly above, as shown in FIG4. However, the irradiation angle must be controlled to the optimal angle by matching it with the thermal conductivity of the single crystal material and the thickness of the thin plate-shaped single crystal 40 to be manufactured.

[0095] In this way, the peripheral area of ​​the upper side 14 of the raw material block 12, excluding the center, will melt earlier than the center, while the center, which is not irradiated by laser light 16a, will melt due to heat conduction from the melt 18 of the already melted peripheral area.

[0096] Therefore, the temperature in the center can be controlled to be lower than that in the peripheral area, so that the melt 18 (melt retention pool) on the upper side 14 of the raw material block 12 has such a temperature distribution, thereby enabling the stable and continuous growth of the thin plate-shaped single crystal 40 from the center.

[0097] That is, as shown in Figures 5 and 6, by irradiating the peripheral area excluding the center of the upper side surface 14 of the raw material block 12 with laser light 16a, a deeper melt 18 is formed in the peripheral area, while a shallower and lower temperature melt 18 is formed in the center.

[0098] Furthermore, as shown in Figures 1, 3, and 4, it is preferable to provide a preheating unit 70 around the raw material block 12 to preheat the raw material block 12. Before the surface of the upper side 14 of the raw material block 12 is melted by the infrared irradiation unit 20, the raw material block 12 is preheated to near its melting point. If such preheating is provided, the amount of infrared radiation 16 irradiated by the infrared irradiation unit 20 can be significantly reduced, and the range of the molten liquid 18 (molten liquid retention pool) can be finely adjusted by finely adjusting the position or the amount of irradiation.

[0099] On the other hand, a lifting unit 30 is provided above the chamber 80. The lifting unit 30 immerses the lower side 34 of the thin plate-shaped single crystal seed 32 in the melt 18 obtained by melting the raw material block 12 on the surface of the upper side 14 by the infrared irradiation unit 20, and pulls the thin plate-shaped single crystal seed 32 upward from the immersed state.

[0100] The lifting unit 30 is not particularly limited, but it is preferably a winding unit 50 that continuously winds the manufactured thin sheet-shaped single crystal 40 into a roll shape. In terms of specific configuration, it includes a winding shaft 36 for continuously winding the manufactured thin sheet-shaped single crystal 40 and a rotating unit 38 for rotating the winding shaft 36.

[0101] Here, the size of the lower side surface 34 of the thin plate-shaped single crystal seed 32 is set to be slightly smaller than the upper side surface 14 of the raw material block 12. For example, in terms of their specific size relationship, the size of the upper side surface 14 of the raw material block 12 is set to be several mm larger than the size of the lower side surface 34 of the thin plate-shaped single crystal seed 32, both in the thickness direction and the transverse direction. That is, it is set to be large enough that the lower side surface 34 of the thin plate-shaped single crystal seed 32 can be completely immersed in the melt 18.

[0102] Then, as shown in Figure 7, the lower side 34 of the thin plate-shaped single crystal seed 32 is immersed in the center of the melt 18 obtained on the surface of the upper side 14 of the raw material block 12 by the infrared irradiation unit 20 through the lifting unit 30. In this way, the growth of single crystal begins from the lower side 34 of the immersed thin plate-shaped single crystal seed 32, and the thin plate-shaped single crystal seed 32 is pulled upward through the lifting unit 30, thereby continuously producing thin plate-shaped single crystals 40.

[0103] The thickness of the thin plate-shaped single crystal 40 to be manufactured can be adjusted by factors such as the steady-state melt temperature and the pulling speed of the thin plate-shaped single crystal seed 32. For example, it can be set to a thickness ranging from 100 μm to over 3000 μm. However, when the thickness of the thin plate-shaped single crystal 40 exceeds 500 μm, the winding unit 50 becomes larger. Therefore, when it exceeds 500 μm, it can also be pulled upwards without winding to form a finished product. In particular, when manufacturing silicon thin plate-shaped single crystals for solar cells, the thickness of the thin plate-shaped single crystal 40 is preferably in the range of 200 μm to 400 μm.

[0104] Furthermore, there is a correlation between melt temperature and pulling speed. That is, when the melt temperature is high, the amount of cooling required for the growth of the thin-plate single crystal 40 increases, thus slowing down the pulling speed. When the melt temperature is low, the productivity of the thin-plate single crystal 40 can be improved by accelerating the pulling speed. However, if the pulling speed is too fast, so-called "crystallization growth" is likely to occur, which degrades the crystallization characteristics of the thin-plate single crystal 40. Therefore, it is better to adjust the pulling speed appropriately.

[0105] Furthermore, the thickness of the thin plate-shaped single crystal seed 32 immersed in the melt 18 can be set to, for example, about 300 μm to 500 μm. If the thin plate-shaped single crystal seed 32 is of such a thickness, then the thin plate-shaped single crystal 40 of the desired thickness can be continuously manufactured by adjusting the melt temperature and the pulling speed, which is therefore preferable.

[0106] Furthermore, Figures 1 and 4 are illustrated with the thickness of the thin plate-shaped single crystal 40 being different from the thickness of the thin plate-shaped single crystal seed 32. However, this is only done intentionally to distinguish between the thin plate-shaped single crystal 40 and the thin plate-shaped single crystal seed 32 in the figures, and there is no particular limitation on the thickness relationship between the two.

[0107] Alternatively, it is preferable to pre-suspend a plurality of thin plate-shaped single crystal seeds 32 (3 in Figure 7) through heat-resistant and high-strength fine wires 52 on the winding shaft 36 of the winding unit 50. In particular, if the thickness of the portion of the thin plate-shaped single crystal seed 32 in which the fine wires 52 are mounted is set to be less than the thickness of the thin plate-shaped single crystal seed 32, then when the winding shaft 36 winds the thin plate-shaped single crystal 40, it can reliably prevent the surface of the thin plate-shaped single crystal 40 from contacting the fine wires 52 and causing damage.

[0108] There is no particular limitation on the method of mounting the fine wire 52 on the thin plate-shaped single crystal seed 32. For example, it can be configured to provide a plurality of through holes for connecting the fine wire 52 at the end of the thin plate-shaped single crystal seed 32, and to provide grooves on both sides of the thin plate-shaped single crystal seed 32 in a manner that connects the through holes. When the fine wire 52 is connected to the thin plate-shaped single crystal seed 32, the fine wire 52 will be fitted into the groove, preventing the fine wire 52 from going to a position further out than the thin plate-shaped single crystal seed 32. By configuring it in this way, when winding the thin plate-shaped single crystal 40, it is possible to reliably prevent the surface of the thin plate-shaped single crystal 40 from contacting the fine wire 52 and causing damage.

[0109] Furthermore, in this thin plate-shaped single crystal manufacturing apparatus 10, it is preferable to pre-install an anti-vibration component 60 and a shielding component 62 between the lifting unit 30 and the raw material block 12. The anti-vibration component 60 prevents the continuously manufactured thin plate-shaped single crystal 40 from vibrating and keeps it within a predetermined range to avoid displacement of the growth position. The shielding component 62 shields the radiant heat emitted from the melt 18 from being difficult to transfer to the continuously manufactured thin plate-shaped single crystal 40.

[0110] By setting up anti-vibration components 60, the situation where the growth position of the manufactured thin plate-shaped single crystal 40 is displaced due to excessive left and right vibration can be suppressed, and high-quality thin plate-shaped single crystal 40 can be continuously manufactured.

[0111] Furthermore, by setting the shielding member 62, the manufacturing speed of the thin plate-shaped single crystal 40 can be accelerated. That is, although the method of melting the raw material and solidifying it into a single crystal is called the melt method, the growth rate of the single crystal in the melt method is accelerated by the efficient discharge of the latent heat of crystallization released during crystallization and solidification through heat conduction in the single crystal in contact with the melt.

[0112] Therefore, if the shielding member 62 is provided in a manner that does not block the optical path of the infrared 16 (laser light 16a), the amount of radiant heat transmitted to the thin plate-shaped single crystal 40 can be reduced, the temperature of the thin plate-shaped single crystal 40 can be avoided, and the latent heat of crystallization can be efficiently discharged, thereby improving the manufacturing efficiency of the thin plate-shaped single crystal 40.

[0113] In this way, by using this thin-plate single crystal manufacturing apparatus 10, thin-plate single crystals 40 can be continuously manufactured. However, if the thin-plate single crystals 40 are manufactured continuously, the amount of melt 18 obtained on the surface of the upper side 14 of the raw material block 12 will decrease, and the position of the upper side 14 will drop. If this happens, the position of the infrared irradiation by the infrared irradiation unit 20 must be controlled to the desired position.

[0114] In this embodiment, in addition to controlling the irradiation position of the infrared 16, the platform 82 on which the raw material block 12 is placed is provided with a position control unit 84 for controlling the vertical position of the platform 82.

[0115] By having such a position control unit 84, even if the position of the molten liquid 18 on the upper side 14 of the raw material block 12 decreases as the thin plate-shaped single crystal 40 is pulled up continuously, the stage 82 can still be raised to keep the position of the molten liquid 18 on the upper side 14 of the raw material block 12 at the same position as the original position, and the liquid surface position of the molten liquid 18 can always be set to the same position.

[0116] Therefore, as long as the infrared light 16 is continuously irradiated at the same position, the thin plate-shaped single crystal 40 can be manufactured continuously with a stable yield. Here, as shown in Figures 4 and 6, when the laser light 16a is vertically irradiated onto the upper side 14 of the raw material block 12 from directly above the raw material block 12, even if the position of the upper side 14 of the raw material block 12 changes, the temperature of the melt 18 will not change, so the position of the upper side 14 of the raw material block 12 does not need to be controlled. Furthermore, the raw material block 12 used in the aforementioned thin-plate single crystal manufacturing apparatus 10 is a raw material block 12 composed of the material of the thin-plate single crystal 40 to be manufactured. However, when the material of the thin-plate single crystal 40 is a decomposed and molten substance, even if the raw material block 12 is directly melted and solidified by the thin-plate single crystal manufacturing apparatus 10, the target thin-plate single crystal 40 still cannot be obtained.

[0117] Therefore, a liquid phase composition in which the amount of liquid phase is in equilibrium with the composition of the material of the thin plate-shaped single crystal 40 to be manufactured is first placed on the upper surface 14 of the raw material block 12, and then melted. In this way, a state in which the dissolved solvent is formed on the upper surface 14 of the raw material block 12.

[0118] After that, when manufacturing the thin plate-shaped single crystal 40, since the same amount of raw material block 12 as the one to be solidified as a single crystal is melted, the amount and composition of the solvent do not change from the beginning to the end. On the surface, only the appearance of the solvent phase gradually dissolving the raw material block 12 and moving while precipitating the single crystal can be seen.

[0119] This process is called the "solvent migration method". When the thin plate single crystal 40 obtained by this thin plate single crystal manufacturing apparatus 10 is a decomposed and melted substance or a solid solution containing additives, it is important to use the "solvent migration method" to make the additive concentration in the obtained thin plate single crystal 40 homogeneous.

[0120] [Second Implementation Form] Next, a second embodiment of the thin-plate single crystal manufacturing apparatus 10 of the present invention will be described. Figures 8 and 9 show the thin-plate single crystal manufacturing apparatus 10 in the second embodiment of the present invention.

[0121] The thin-plate single crystal manufacturing apparatus 10 shown in Figures 8 and 9 is basically the same as the thin-plate single crystal manufacturing apparatus 10 of the first embodiment shown in Figures 1 to 7. Therefore, the same component is marked with the same component symbol and its detailed description is omitted. Only the different parts are described.

[0122] The thin-plate single crystal manufacturing apparatus 10 in the second embodiment of the present invention is as shown in FIG8 and FIG9. The difference between it and the thin-plate single crystal manufacturing apparatus 10 in the first embodiment is that a gas introduction device 90 is provided in the chamber 80 to fill the chamber 80 with ambient gas containing additives.

[0123] A gas introduction device 90 is provided on the upper side of the chamber 80 to introduce ambient gas into the chamber 80 through the introduction pipe 92. In addition, an exhaust pipe 94 is provided on the lower side of the chamber 80 to exhaust ambient gas to the outside of the chamber 80.

[0124] In this way, the chamber 80 can be maintained in an environment filled with a gas suitable for manufacturing thin-plate single crystals 40, and high-quality thin-plate single crystals 40 with homogeneous additive concentration can be continuously manufactured.

[0125] In addition, the ambient gas only needs to be one that matches the material properties of the thin plate-shaped single crystal 40 to be manufactured. For example, when manufacturing a thin plate-shaped single crystal of N-type silicon, it is preferable to introduce high-purity argon gas containing phosphine (PH3) at the optimal concentration into the chamber 80 as the ambient gas.

[0126] Furthermore, as shown in FIG9, for example, the window 22 used to guide the infrared 16 (laser light 16a) irradiated from the infrared irradiation unit 20 to the chamber 80, or the reflector 24 used to guide the infrared 16 (laser light 16a) irradiated to the chamber 80 to the upper side 14 of the raw material block 12, can be covered by the cover member 42, and the ambient gas can be actively introduced into the cover member 42 from the gas introduction device 90.

[0127] By introducing ambient gas into the cover layer component 42 in this way, it can prevent... By attaching evaporates generated from the melt 18 to windows 22, mirrors 24, etc., high-quality thin-plate single crystals 40 with homogeneous additive concentration can be produced continuously and stably with good production rates.

[0128] [Third Implementation Form] Next, a third embodiment of the thin-plate single crystal manufacturing apparatus 10 of the present invention will be described. Figures 10 and 11 show the thin-plate single crystal manufacturing apparatus 10 in the third embodiment of the present invention.

[0129] The thin-plate single crystal manufacturing apparatus 10 shown in Figures 10 and 11 is basically the same as the thin-plate single crystal manufacturing apparatus 10 of the first embodiment shown in Figures 1 to 7. Therefore, the same component is marked with the same element symbol and its detailed description is omitted. Only the different parts are described.

[0130] The thin-plate single crystal manufacturing apparatus 10 in the third embodiment of the present invention is as shown in FIG10 and FIG11. The difference between it and the thin-plate single crystal manufacturing apparatus 10 in the first embodiment is that a plurality of lifting units 30 (two in FIG10) are provided on the upper part of the raw material block 12.

[0131] Specifically, the lifting unit 30 (winding unit 50) is arranged in two side by side on the upper part of the chamber 80. Thin plate-shaped single crystal seeds 32, 32 are immersed in the melt 18 on the upper side 14 of the raw material block 12. They are then pulled upward by the lifting units 30, 30 (winding units 50, 50) respectively, thereby producing thin plate-shaped single crystals 40, 40 respectively. If a plurality of such lifting units 30 are provided on the upper part of the raw material block 12, the manufacturing efficiency of the thin plate-shaped single crystal 40 can be improved compared with the case of a single lifting unit 30.

[0132] <Methods for Manufacturing Thin Plate-Shaped Single Crystals> Next, the method for manufacturing thin-plate single crystals using the thin-plate single crystal manufacturing apparatus 10 of the present invention will be described.

[0133] First, as shown in Figure 12(a), the raw material block 12 is placed on the stage 82 inside the chamber 80 and the chamber 80 is sealed. The thin plate-shaped single crystal seed 32 is arranged on the upper part of the upper side of the raw material block 12 in such a way that the length direction of the raw material block 12 and the extension direction of the thin plate-shaped single crystal seed 32 are aligned. The thin plate-shaped single crystal seed 32 is suspended from the winding shaft 36 of the winding unit 50 through the thin wire 52.

[0134] In addition, within the chamber 80, the gas environment is evacuated through an exhaust pipe (not shown), and an ambient gas matching the properties of the material to be manufactured, the thin plate-shaped single crystal 40, is introduced into the chamber 80 through a gas introduction device (not shown).

[0135] Next, the temperature of the raw material block 12 is raised to near the melting point by the preheating unit 70. Then, as shown in FIG12(b), infrared light 16 (laser light 16a) is irradiated on the upper side 14 of the raw material block 12 by the infrared irradiation unit 20, so that the surface of the upper side 14 melts.

[0136] The irradiation area of ​​infrared 16 (laser light 16a) is a horizontally elongated hollow quadrilateral shape. The peripheral area of ​​the upper side surface 14 of the raw material block 12, excluding the center, is irradiated with laser light 16a in a matched manner to form the horizontally elongated hollow quadrilateral irradiation area.

[0137] In this way, the peripheral area of ​​the upper side 14 of the raw material block 12, excluding the center, will melt earlier than the center, while the center, which is not irradiated by laser light 16a, will melt due to heat conduction from the melt 18 of the already melted peripheral area.

[0138] Next, as shown in Figure 12(c), the lower side 34 of the thin plate-shaped single crystal seed 32 is immersed in the center of the melt 18 obtained by the upper side 14 of the raw material block 12 through the lifting unit 30 (winding unit 50), and the growth of single crystal begins from the lower side 34 of the thin plate-shaped single crystal seed 32.

[0139] Next, as shown in Figure 13(a), the thin plate-shaped single crystal seed 32 is pulled upward through the lifting unit 30 (winding unit 50) to continuously manufacture the thin plate-shaped single crystal 40. Secondly, as shown in Figure 13(b), during the continuous fabrication of the thin plate-shaped single crystal 40, the position of the stage 82 is moved upward by the position control unit 84. In this way, even if the position of the molten 18 of the raw material block 12 drops as it is pulled up, the position of the raw material block 12 is still controlled in a way that keeps it in its original position, so that the liquid surface position of the molten 18 remains at the same position. Here, as shown in Figures 4 and 6 of the thin plate single crystal manufacturing apparatus 10, when laser light 16a is vertically irradiated onto the upper side 14 of the raw material block 12 from directly above the raw material block 12, even if the position of the upper side 14 of the raw material block 12 changes, the temperature of the melt 18 will not change. Therefore, it is not necessary to control the position of the upper side 14 of the raw material block 12 to a certain position.

[0140] Finally, as shown in Figure 13(c), the irradiation amount of infrared 16 (laser light 16a) from infrared irradiation unit 20 is increased, the temperature of melt 18 is increased, the thin plate single crystal 40 is cut off from melt 18, the winding of the thin plate single crystal 40 continuously manufactured by lifting unit 30 (winding unit 50) is ended, and the irradiation by infrared 16 (laser light 16a) from infrared irradiation unit 20 is ended, thus completing the manufacturing of thin plate single crystal 40. [Example]

[0141] [Example 1] Using the thin-plate single crystal manufacturing apparatus 10 of the present invention, a thin-plate single crystal 40 of phosphorus-added N-type silicon is manufactured.

[0142] In addition, a cubic raw material block 12 with a width of 400 mm, a thickness of 50 mm, and a height of 500 mm is used as the raw material block 12. On the other hand, as a thin plate-shaped single crystal seed 32, a thin plate-shaped single crystal seed 32 of silicon with a width of 350 mm, a thickness of 0.3 mm, and a height of 100 mm is used. Silicon has the property of easily presenting a flat surface called a facet in the (111) direction, and this flat surface is set as the plate surface of the thin plate-shaped single crystal seed 32. The thin plate-shaped single crystal seed 32 is pre-installed on the winding shaft 36 of the winding unit 50 through three fine wires 52.

[0143] First, the raw material block 12 is placed on the stage 82 inside the chamber 80, the chamber 80 is sealed, and the internal gas environment is set to a vacuum state. Secondly, ambient gas is introduced into chamber 80. The ambient gas system uses high-purity argon gas, and in order to add phosphorus, a necessary amount of phosphine (PH3) gas is used.

[0144] First, the raw material block 12 is heated to near its melting point using the preheating unit 70. After confirming the heating, laser beams 20 mm wide and 396 mm long are irradiated from the center and peripheral areas (excluding the outermost periphery) of the upper side surface 14 of the raw material block 12 from both the left and right sides at an angle of 60 degrees to the horizontal direction and 2 mm from the end portion. Simultaneously, laser beams 16a are irradiated from both ends of the raw material block 12 along its length direction, at an angle of 60 degrees to the horizontal direction, forming irradiation areas 2 mm from the ends and 6 mm wide. The shape of the irradiation area is an elongated hollow quadrilateral shape in the horizontal direction. This causes the entire upper side surface 14 to melt.

[0145] The winding shaft 36 of the winding unit 50 is rotated, and the lower side 34 of the aforementioned thin plate-shaped single crystal seed 32 of silicon is immersed in the center of the melt 18 obtained by melting. The thin plate-shaped single crystal 40 is grown from the lower side 34 of the thin plate-shaped single crystal seed 32. At the same time, the winding shaft 36 is rotated in the opposite direction to pull the thin plate-shaped single crystal seed 32 upward. The thin plate-shaped single crystal 40 is continuously wound into the winding shaft 36 in a cylindrical shape at the upper part to produce a long strip of thin plate-shaped single crystal 40 with a length of more than 10m.

[0146] In addition, the thin plate-shaped single crystal seed 32 is set on the winding shaft 36 of the winding unit 50 with carbon fiber fine wire 52 with a diameter of about 0.05 mm. The rotation direction and rotation speed of the winding shaft 36 are controlled by the rotation unit 38, thereby causing the thin plate-shaped single crystal seed 32 to move in the up and down direction.

[0147] It has been confirmed that if the thin plate-shaped single crystal seed 32 is immersed in the center of the melt 18, it will directly begin to crystallize, and the immersed part of the thin plate-shaped single crystal seed 32 will become thicker. However, if it is placed directly, the thickened part will melt and become thinner.

[0148] In this state, the thin plate-shaped single crystal seed 32 is pulled upwards, and the thickness of the manufactured thin plate-shaped single crystal 40 is confirmed by a camera. While adjusting the pulling speed and the irradiation intensity of the laser light 16a, the thickness is controlled at 0.3 mm as the winding shaft 36 is rotated, and the thin plate-shaped single crystal 40 is continuously wound onto the winding shaft 36.

[0149] Furthermore, it was confirmed that if the pulling speed of the thin plate-shaped single crystal seed 32 decreases, the thickness of the thin plate-shaped single crystal 40 increases; conversely, if the pulling speed increases, the thickness of the thin plate-shaped single crystal 40 decreases. The melt temperature was adjusted by continuously pulling the thin plate-shaped single crystal 40 with a thickness of 0.3 mm at a speed of 30 mm per minute.

[0150] Here, since the liquid surface position of the molten 18 of the raw material block 12 will drop as the thin plate-shaped single crystal 40 is pulled up, in order to maintain the original position, the position of the stage 82 on which the raw material block 12 is placed is controlled at a predetermined position by the position control unit 84, so that the liquid surface position of the molten 18 of the raw material block 12 is always at the same position as the original position.

[0151] The thin plate-shaped single crystal 40, which is longer than 10m, has a thickness of 0.3mm, and a width of 383 to 386mm, was thus manufactured. It was confirmed by secondary ion mass spectrometry (SIMS) that the concentration of phosphorus, which is an additive, is the optimal composition and homogeneous, indicating that it is of high quality. This confirms the superiority of the thin plate-shaped single crystal manufacturing apparatus 10 and the thin plate-shaped single crystal manufacturing method of the present invention.

[0152] Next, a summary of the thin-plate single crystal manufacturing apparatus 10 of the present invention and the thin-plate single crystal manufacturing method of the thin-plate single crystal manufacturing apparatus 10 will be described. The thin-plate single crystal manufacturing apparatus 10 and the thin-plate single crystal manufacturing method according to the present invention are able to continuously and stably manufacture thin-plate single crystals 40 because the melting of the raw material block 12 and the single crystallization from the resulting melt 18 can be controlled relatively independently.

[0153] That is, heating is required to melt the raw material block 12 to obtain the melt 18, but cooling is required to solidify and crystallize the melt 18. The two are opposite. Therefore, the present invention is configured such that the portion to be crystallized (the center of the melt 18) is not directly irradiated with laser light 16a, but the portion other than the portion to be crystallized (the peripheral area excluding the center of the melt 18) is irradiated with laser light 16a, causing the upper side surface 14 of the raw material block 12 to melt, and the heat of the melt 18 is conducted to the portion to be crystallized (the center of the melt 18), so that the center of the upper side surface 14 also forms melt 18.

[0154] In this way, the temperature of the part to be crystallized (the center of the molten liquid 18) becomes lower than the temperature of the part that melts under the irradiation of laser light 16a (the peripheral area of ​​the molten liquid 18 excluding the center), making it easier to crystallize.

[0155] If the thin plate-shaped single crystal seed 32 is immersed in the center of the molten liquid 18, the heat of the molten liquid 18 will be transferred to the lower surface 34 of the immersed thin plate-shaped single crystal seed 32. Therefore, the temperature of the molten liquid in contact with the lower surface 34 will decrease, and crystallization will proceed rapidly. If left temporarily, the heat conducted and escaped by the thin plate-shaped single crystal seed 32 will become stable. At this point, the rapidly solidified part will gradually melt due to the heat from the surrounding molten liquid 18 and become stable.

[0156] If the thin plate-shaped single crystal seed 32 is pulled upward in this state, it will move towards the low temperature section and crystallize on the lower side 34 that is in contact with the melt 18. If the pulling speed of the thin plate-shaped single crystal seed 32 is accelerated, making crystallization unable to keep up, the thickness of the manufactured thin plate-shaped single crystal 40 will become thinner. If the pulling speed is slowed down, crystallization will be promoted, so the thickness of the thin plate-shaped single crystal 40 will increase.

[0157] Therefore, if the temperature of the melt 18 is controlled to be low, crystallization becomes easier and the thickness of the thin plate-shaped single crystal 40 becomes thicker. Thus, even if the pulling speed is accelerated, the thin plate-shaped single crystal 40 of the predetermined thickness can be continuously manufactured.

[0158] Furthermore, accelerating the pulling speed can improve the manufacturing efficiency of the thin-plate single crystal 40, but too fast a speed increases the possibility of crystal growth. If crystal growth occurs, the concentration of phosphorus, which is an additive, will fluctuate significantly in localized areas, degrading the characteristics of the single crystal. Therefore, it is important to suppress the occurrence of crystal growth and accelerate the pulling speed as much as possible to continuously manufacture the thin-plate single crystal 40.

[0159] Furthermore, according to the present invention, even with so-called inconsistently dissolved substances such as decomposed molten materials or solid solution single crystals, it is possible to begin manufacturing thin, high-quality, plate-shaped single crystals 40 with homogeneous composition. Such thin, plate-shaped single crystals 40 with homogeneous composition of inconsistently dissolved materials cannot be manufactured by previous methods.

[0160] In other words, if one wishes to manufacture single crystals by melting raw materials to form a molten liquid and then solidifying it, that is, by using the so-called molten liquid method to manufacture single crystals of homogeneous composition of these inconsistent molten materials, there is in principle no other method except to pre-prepare the raw material block 12 of the desired composition and use a solvent composed of a solvent composition that coexists in equilibrium with the desired composition to simultaneously dissolve the raw material block 12 and precipitate the single crystal from the solvent, that is, the so-called solvent movement method.

[0161] In this invention, after the solvent phase components are prepared in a necessary amount on the upper side 14 of the raw material block 12, it is irradiated with infrared light 16 and melted to form a solvent solution. Then, by simultaneously carrying out the solvent-based single crystal production and the dissolution of the raw material block 12 into the solvent, a solvent transfer method is applied, and a thin plate-shaped single crystal 40 with a homogeneous composition can be manufactured.

[0162] The above describes the thin-plate single crystal manufacturing apparatus 10 and the thin-plate single crystal manufacturing method using the present invention, but the present invention is not limited to the above embodiments.

[0163] For example, the above-described thin-plate single crystal manufacturing apparatus 10 is described in the first to third embodiments, but it can also be combined to form the thin-plate single crystal manufacturing apparatus 10 of the present invention. That is, for example, the second and third embodiments can be combined in the first embodiment to form the thin-plate single crystal manufacturing apparatus 10.

[0164] Furthermore, the aforementioned thin-plate single crystal manufacturing apparatus 10 is an example in which the infrared irradiation unit 20 is arranged in a manner that irradiates the sides of the quadrilateral shape in parallel, but it is not limited to this, and there may also be only one infrared irradiation unit 20.

[0165] Furthermore, if the laser light 16a can be irradiated in a way that matches the peripheral area excluding the center of the upper side surface 14 of the raw material block 12 to form an irradiation area with a horizontally elongated hollow quadrilateral shape, then the elongated hollow quadrilateral irradiation area can also be formed by a plurality of laser lights 16a, and the cross-sectional shape of the laser light 16a irradiated by the infrared irradiation unit 20 or the plurality of laser lights 16a is not limited.

[0166] That is, it is possible to irradiate the upper surface 14 of the raw material block 12 with laser light 16a having a U-shaped cross-section from the left and right sides respectively, and form an irradiation region having a horizontally elongated hollow quadrangular cross-sectional shape by two laser lights 16a, 16a having a U-shaped cross-section, or form an irradiation region having a horizontally elongated hollow quadrangular cross-sectional shape by four laser lights having a rod-shaped cross-section.

[0167] Furthermore, although the thickness of the thin plate-like single crystal 40 to be manufactured is described as being about 100 μm to 3000 μm, in principle, a thickness greater than this can also be manufactured, for example, a thickness of 5000 μm or more, and the thickness is not limited to the above range.

[0168] Moreover, regarding the thickness of the thin plate-like single crystal seed 32 immersed in the melt 18d, although it is described as being about 300 μm to 500 μm, for example, in principle, the thin plate-like single crystal 40 can be manufactured even with a thickness outside this range, and the thickness is not limited to the above range.

[0169] Such a thin plate-like single crystal manufacturing apparatus 10 and a thin plate-like single crystal manufacturing method of the present invention can be variously modified within the scope not departing from the object of the present invention.

[0170] 10: Thin plate-like single crystal manufacturing apparatus 12: Raw material block for manufacturing thin plate-like single crystal (raw material block) 14: Upper surface 16: Infrared ray 16a: Laser light 18: Melt 20: Infrared ray irradiation unit 22: Window 24: Reflecting mirror 30: Lifting unit 32: Thin plate-like single crystal seed 34: Lower surface 36: Winding shaft 38: Rotating unit 40: Thin plate-like single crystal 42: Cover member 50: Take-up unit 52: Fine wire 54: Supply unit 56: Supply pipe 60: Seismic-resistant components 62: Shielding components 70: Preheating Unit 80: Chamber 82: Platform 84: Position Control Unit 90: Gas introduction device 92: Import tube 94: Discharge pipe

Claims

1. A thin-plate single crystal manufacturing apparatus comprising the following units: an infrared irradiation unit for irradiating an upper surface of a raw material block for manufacturing a thin-plate single crystal with infrared light, causing the surface of the upper surface to melt; and a lifting unit for immersing a lower surface of a thin-plate single crystal seed in the molten liquid obtained from the surface of the upper surface by the infrared irradiation unit, and for lifting the thin-plate single crystal seed upward from the immersed state; and the thin-plate single crystal manufacturing apparatus is configured such that: the lower surface of the thin-plate single crystal seed is immersed in the molten liquid obtained from the surface of the upper surface of the raw material block for manufacturing a thin-plate single crystal by the infrared irradiation unit through the lifting unit, thereby growing a single crystal from the lower surface of the immersed thin-plate single crystal seed, and the thin-plate single crystal seed is lifted upward through the lifting unit, thereby continuously manufacturing thin-plate single crystals; the infrared light irradiated by the infrared irradiation unit is laser light; The laser light irradiation area is shaped as a slender hollow quadrilateral in the horizontal direction. The laser light is irradiated in the peripheral area of ​​the upper side surface of the aforementioned thin plate-shaped single crystal manufacturing raw material block, excluding the center. The laser light is formed in the manner of creating the aforementioned hollow quadrilateral irradiation area.

2. The sheet-like single crystal manufacturing apparatus as described in claim 1, wherein, The aforementioned lifting unit is a winding unit that continuously winds the aforementioned thin plate-shaped single crystal into a roll shape. The aforementioned winding unit includes: a winding shaft that continuously winds the aforementioned thin plate-shaped single crystal, and a rotating unit that rotates the aforementioned winding shaft. The thin plate-shaped single crystal manufacturing apparatus is configured such that the aforementioned thin plate-shaped single crystal seed is suspended from the aforementioned winding shaft.

3. The sheet-like single crystal manufacturing apparatus as described in claim 2, wherein, The aforementioned thin plate-shaped single crystal seed system is suspended from the aforementioned roll shaft by multiple fine threads.

4. The sheet-like single crystal manufacturing apparatus as described in claim 3, wherein, In the aforementioned thin plate-shaped single crystal seed, the thickness of the portion on which the aforementioned fine wire is installed is less than or equal to the thickness required to manufacture the aforementioned thin plate-shaped single crystal.

5. The thin-plate single crystal manufacturing apparatus as described in claim 1, wherein, On the upper side of the aforementioned raw material block for manufacturing thin plate-shaped single crystals, a liquid phase composition that coexists in equilibrium with the composition of the aforementioned thin plate-shaped single crystals is initially prepared in a necessary amount.

6. The sheet-like single crystal manufacturing apparatus as described in claim 1, wherein, Between the aforementioned lifting unit and the aforementioned raw material block for manufacturing thin plate-shaped single crystals, an anti-vibration component is provided to prevent vibration of the aforementioned thin plate-shaped single crystals to be continuously manufactured.

7. The sheet-like single crystal manufacturing apparatus as described in claim 1, wherein, Between the aforementioned lifting unit and the aforementioned raw material block for manufacturing thin plate-shaped single crystals, there is a shielding member that shields the radiant heat emitted from the aforementioned molten liquid from being transmitted to the aforementioned thin plate-shaped single crystals that have been continuously manufactured.

8. The sheet-like single crystal manufacturing apparatus as described in claim 1, wherein, The aforementioned raw material block for manufacturing thin plate-shaped single crystals is a slightly rectangular cuboid.

9. The sheet-like single crystal manufacturing apparatus as described in claim 1, wherein, Compared to the size of the lower side of the aforementioned thin plate-shaped single crystal seed, the size of the upper side of the aforementioned raw material block for manufacturing thin plate-shaped single crystal is set to be several millimeters larger in both the thickness direction and the transverse direction.

10. The thin-plate single crystal manufacturing apparatus as described in claim 1, comprising: a stage for holding the aforementioned raw material block for manufacturing the thin-plate single crystal, and a position control unit for position control in a manner that causes the position of the aforementioned stage to be a predetermined position.

11. The sheet-like single crystal manufacturing apparatus as described in claim 1, wherein, The aforementioned lifting unit is configured such that the lower side of the aforementioned thin plate-shaped single crystal seed is immersed in the center of the molten material on the upper side of the raw material block for manufacturing the thin plate-shaped single crystal, which is melted by the aforementioned infrared irradiation unit.

12. The sheet-like single crystal manufacturing apparatus as described in claim 1, wherein, Around the aforementioned sheet-shaped single crystal manufacturing raw material block, a preheating unit is provided for preheating the aforementioned sheet-shaped single crystal manufacturing raw material block.

13. The sheet-like single crystal manufacturing apparatus as described in claim 1, wherein, The chamber is equipped with at least the aforementioned thin plate-shaped raw material block for manufacturing single crystals, and the aforementioned lifting unit is provided at the upper part of the chamber.

14. The thin-plate single crystal manufacturing apparatus as described in claim 13 is equipped with a gas introduction device that fills the aforementioned chamber with an ambient gas containing additives.

15. The sheet-like single crystal manufacturing apparatus as described in claim 1, wherein, A plurality of the aforementioned lifting units are provided on the upper part of the aforementioned thin plate-shaped raw material block for manufacturing single crystals.

16. The sheet-like single crystal manufacturing apparatus as described in claim 1, wherein, The thickness of the aforementioned thin plate-shaped single crystal seed is in the range of 300 μm to 500 μm.

17. A method for manufacturing a thin-plate single crystal, comprising at least the following steps: a melting step, wherein infrared light is irradiated onto the upper side of a raw material block for manufacturing the thin-plate single crystal through an infrared irradiation unit, causing the surface of the upper side of the raw material block to melt; a growing step, wherein the lower side of a thin-plate single crystal seed is immersed in the melt obtained on the surface of the upper side of the raw material block in the melting step through a lifting unit, and single crystal growing begins from the lower side of the thin-plate single crystal seed; and a continuous manufacturing step, wherein the thin-plate single crystal seed that begins to grow single crystal in the growing step is pulled upwards to continuously manufacture thin-plate single crystals; wherein in the melting step, the infrared light irradiated by the infrared irradiation unit is laser light, and the irradiation area of ​​the laser light is a slender hollow quadrilateral shape in the horizontal direction. The peripheral area of ​​the upper side surface of the aforementioned thin plate-shaped single crystal manufacturing raw material block, excluding the center, is irradiated with laser light in a manner that forms the aforementioned hollow quadrilateral irradiation area.

18. The method for manufacturing a thin plate-shaped single crystal as described in claim 17, wherein, Following the aforementioned continuous manufacturing steps, there is a winding step, in which the aforementioned thin plate-shaped single crystal, which has been continuously manufactured, is wound into a roll shape.

19. The method for manufacturing a thin plate-shaped single crystal as described in claim 17, wherein, In the aforementioned melting step, when the aforementioned thin plate-shaped single crystal is to be produced by decomposing and melting the material, a liquid phase composition that coexists in equilibrium with the composition of the aforementioned thin plate-shaped single crystal is first arranged on the upper side of the raw material block for producing the aforementioned thin plate-shaped single crystal in a necessary amount.

20. The method for manufacturing a thin plate-shaped single crystal as described in claim 17, wherein, In the aforementioned melting step, when the aforementioned thin plate-shaped single crystal is to be manufactured as a solid solution containing additives, a liquid phase composition that coexists in equilibrium with the composition of the aforementioned thin plate-shaped single crystal is first prepared on the upper side of the raw material block for manufacturing the aforementioned thin plate-shaped single crystal in a necessary amount.

21. The method for manufacturing a thin plate-shaped single crystal as described in claim 17, wherein, In the aforementioned growth step, the lower side of the aforementioned thin plate-shaped single crystal seed is immersed in the center of the molten material on the surface of the upper side of the aforementioned melted thin plate-shaped single crystal manufacturing raw material block.

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