DE102011077862A1 - System, useful for supplying raw material into melt for producing single crystal material, comprises feed device, which comprises reservoir for raw material, housing and unit for conveying raw material from reservoir into crucible - Google Patents

Abstract

The system comprises a feed device (10), which comprises a reservoir (11) for a raw material, a fluid-tight housing and a unit for conveying the raw material from the reservoir into a crucible. The conveying unit comprises a bulk tube (20), a lifting device for the bulk tube such that the feed device is assignable to the crucibles, and a conveyor belt (13) and/or a roller conveyor that is disposed between the reservoir and the bulk tube. The housing comprises a gas connection and/or a vacuum port, and an opening for the bulk tube. The opening comprises a vacuum-compatible closure. The system comprises a feed device (10), which comprises a reservoir (11) for a raw material, a fluid-tight housing and a unit for conveying the raw material from the reservoir into a crucible. The conveying unit comprises a bulk tube (20), a lifting device for the bulk tube such that the feed device is assignable to the crucibles, and a conveyor belt (13) and/or a roller conveyor that is disposed between the reservoir and the bulk tube. The housing comprises a gas connection and/or a vacuum port, and an opening for the bulk tube. The opening comprises a vacuum-compatible closure. The bulk tube comprises a valve with a conical valve plunger (24). A chute is arranged between the conveyor belt and the bulk tube. The reservoir is adjusted for receiving a mass of the raw material of 200 kg. The lifting device comprises a cable winch with a rope that is connected to the bulk tube and/or the valve plunger, and an electric motor that is operatively connected with the cable winch. An independent claim is included for a process for producing a single crystal material.

Description

The invention relates to a system and a method for feeding a starting material into a melt for producing a monocrystalline material.

A system of the type mentioned is, for example US 6,896,732 B2 known.

State of the art

A semi-continuous crystal growth (SCG) process is a process in which several single crystals are drawn from the same crucible. Between each draw, the crucible is refilled between each draw with a quantity of starting material so that a complete, new single crystal can be drawn.

For the production of silicon monocrystals, the starting material in practice has flowable chips or granules of polysilicon. In order to ensure a uniform feeding of the polysilicon in the crucible, the polysilicon is usually present as a granular granules, wherein the granular particles have a spherical shape. A disadvantage of spherical or granular polysilicon is that the available amount is usually insufficient for mass production of single crystals. Furthermore, with the use of small polysilicon granulate particles, there is the risk that microexplosions in the melt occur due to the gas inclusions contained in the individual particles. The micro-explosions can cause splashes from the melt to hit the heating zone. As a result, the properties of the heating zone deteriorate, whereby the service life of the heating zone can be reduced. In addition, the small size of the granules makes it difficult to clean or etch the polysilicon. This impairs the surface purity of the starting material and thus the stability of the drawing process. As a result, the production costs increase.

In the aforementioned US 6,896,732 B2 discloses a supply system for polysilicon particles in a crucible, wherein a reservoir for the polysilicon particles is provided, which comprises a vibration device. Below the reservoir, a slideway is arranged, which promotes the starting material to a bulk tube. The vibration device thereby supports the sliding of the polysilicon particles on the slide track. The feeding system according to US 6,896,732 B2 is used in conjunction with a Czochralski process. For this purpose, the feeder is firmly connected to a crystal pulling system, so that the polysilicon can be filled in each case in the crucible of the crystal pulling system. Similar feeders are off DE 600 13 594 T2 and US 2003/0159647 A1 known.

The known feeders are firmly connected to the crystal puller, in particular the pull shaft of the crystal puller. Furthermore, the mass of the supplied starting material is limited in the known feeders.

Disclosure of the invention

The invention provides a system according to the subject-matter of claim 1 and a method having the features of claim 11.

The invention is based on the idea of providing a system for feeding a starting material into a melt for producing a monocrystalline material with a feed device, which comprises a reservoir for the starting material and a conveying unit for conveying the starting material from the reservoir into a crucible. The delivery unit has a bulk tube. Furthermore, the conveying unit comprises a lifting device for the pouring tube, so that the feeding device can be used mobile, in particular a plurality of crucibles can be assigned.

According to the invention, it is provided that the pouring tube is coupled to a lifting device. In this way, the pouring tube can be raised or lowered. This allows a mobile use of the system according to the invention. At the same time, the distance to the crucible is reduced by lowering the bulk tube, so that an efficient supply of starting material is made possible in the melt.

The feeder is connectable to a process chamber which comprises the crucible. In particular, it is provided that the feed device is releasably connected to a drawing vessel of a process chamber for the production of a monocrystalline material by the Czochralski method. In this way, the mobility of the system according to the invention is further improved since the system according to the invention can be used for a plurality of crucibles or process chambers. In particular, a plurality of process chambers can be supplied with a starting material by a single system according to the invention or connected in a time-delayed manner in order to track the crucibles each with a predetermined amount of starting material.

The feeding device of the system according to the invention is in an embodiment of Invention coupled only for the period of feeding the starting material into the melt with the process chamber, in particular the open vessel. The mobile properties of the system according to the invention make it possible to simultaneously feed the starting material into the crucible while an already pulled single crystal cools in a lock chamber.

According to a further embodiment of the system according to the invention, the feed device has a fluid-tight housing. The fluid-tight housing avoids contamination of the starting material arranged in the reservoir.

The housing may have at least one gas connection and / or one vacuum connection. Through the gas connection, the system can be filled with a process gas or inert gas. Preferably, the housing is filled by means of the gas connection with a noble gas in order to maintain the purity of the drawing process. The vacuum connection can be connected to a vacuum suction. Thus, a negative pressure can be generated in the housing. It is particularly preferred if both a gas connection and a vacuum connection are provided. By adjusting the gas supply pressure and the suction pressure, the process conditions can be adjusted.

The housing may have substantially the same construction as the housing of a lock chamber. In general, the feeder may include the same ports and dimensions as a lock chamber. This ensures that the feed device can be simply connected to a process chamber. In concrete terms, after a pulling operation, the lock chamber equipped with the pulled monocrystal can simply be exchanged for the feed device.

In a further embodiment, the housing has an opening for the pour tube. The opening may comprise a fluid-tight, in particular vacuum-capable, closure. Through the bulk tube opening in the housing of the feeder, the bulk tube can be lowered from the housing into the process chamber. The fluid-tight seal prevents a gas exchange between the housing interior and the environment takes place. Preferably, the closure is vacuum-capable such that a vacuum can be created and maintained within the housing of the feeder.

In a further embodiment of the system according to the invention, the bulk tube has a valve. The valve may comprise a conical valve piston. The conical valve piston allows closing of the bulk tube. Due to the conical valve piston, the valve has a particularly simple construction. Moreover, the conical shape of the valve piston allows a simple and continuous feeding of the starting material into the crucible.

The delivery unit of the system according to the invention may comprise a conveyor belt which is arranged between the storage container and the pouring tube. Alternatively or additionally, the conveyor unit may have a roller conveyor which is arranged between the storage container and the pouring tube. The conveyor belt or the roller conveyor enables a uniform and continuous conveying of the starting material from the reservoir to the pouring tube. The conveyor belt is also controllable. In particular, the conveying speed and the delivery period can be set. Overall, the conveyor belt thus allows a variable adjustment of parameters for the supply of the starting material in the crucible.

A chute can be arranged between the conveyor belt or the roller conveyor and the pouring tube.

The storage container is adapted in particular for receiving a mass of the starting material of at least 100 kg, in particular at least 150 kg, and / or at most 200 kg. The system may be further configured such that a feed rate of up to 40 kg / hr. is reached. The system according to the invention is particularly well suited for mass production, since a relatively short period of time is required between the individual drawing operations in order to fill the crucible with starting material. The production speed is thus increased.

The lifting device of the system according to the invention may comprise a cable winch with a cable which is connected to the pouring tube and / or the valve piston. The winch allows a particularly simple way lifting or lowering the bulk tube. In particular, the winch is well suited for lowering the bulk tube in large process chambers. The invention is not limited to the use of a rope, but also includes the use of chains or similar flexible elongate elements.

The lifting device may also include an electric motor operatively connected to the winch. In this way, the winch is easy to control. In particular, the feed rate of the starting material can be adjusted in the crucible via the control of the electric motor, which is coupled via the winch and the rope to the valve piston.

According to a secondary aspect, the invention is based on the idea of specifying a method for feeding a starting material into a melt for producing a monocrystalline material, wherein a system of the type described above is provided and fluid-tightly connected to a melting chamber. In particular, the connection is vacuum-capable or vacuum-tight. A predetermined amount of the starting material is then conveyed through the pour tube into the crucible.

The inventive method allows a quick and easy refilling of a crucible, in particular a plurality of crucibles, so that the method is well suited for mass production or mass production.

Preferably, the system described above is dissolved after the feeding of the starting material into the crucible of the process chamber and connected fluid-tight for filling a further crucible with another process chamber. In general, the system can thus be connected in succession to different process chambers, so that a single feed system can be used for a plurality of process chambers.

drawings

The invention is explained in more detail below with reference to an embodiment with reference to the accompanying schematic drawings. Show:

1 a cross section through the system according to the invention according to a preferred embodiment in a transport state;

2 a cross section through the system according to 1 , wherein the bulk tube is filled;

3 a detailed view of the spill tube according to 1 in the filled state (batch mode);

4 a detail view of a bulk tube of a system according to the invention according to a further embodiment, wherein the valve of the bulk tube for supplying the starting material is opened in a crucible (continuous mode);

5 a perspective view of a system according to the invention according to a further preferred embodiment; and

6 a cross-sectional view of the system according to 5 ,

Embodiments of the invention

The figures show exemplary embodiments of a system for feeding a starting material into a melt for producing a monocrystalline material, the system comprising a feed device 10 with a storage container 11 and a conveyor unit. The conveyor unit preferably has a conveyor belt 13 , a chute 17 and a pouring tube 20 on.

The system is preferably used for feeding a polysilicon starting material into a process chamber, in particular a crucible arranged in the process chamber, a plant for producing a silicon monocrystal according to the Czochralski method. The system according to the invention is thus suitable for use in semi-continuous crystal growth processes.

The system according to the invention is particularly suitable for feeding polysilicon particles having irregular shapes. Depending on the size of the particles, these are referred to as chips or chunks (chunks, pieces). In contrast, polysilicon granule particles have a regular, spherical shape, also referred to as beads. Although the invention is in principle also suitable for feeding beads into a crucible, it makes it possible, in particular, to supply irregularly shaped particles.

In 1 is the structure of the feeder 10 a system according to the invention shown schematically. The system or feeder 10 is mobile. In particular, the system or the feeder 10 modular. The feeder 10 includes a reservoir 11 for receiving the starting material, preferably a silicon material. The silicon can be doped. The storage tank 11 can have any capacity, which may depend on the size of the crucible and the specific production processes. Preferably, the reservoir holds 11 up to 200 kg of the silicon starting material. It is also possible that the reservoir can hold more than 200 kg of the silicon starting material. Specifically, the reservoir 11 be designed for receiving at least 100 kg, in particular at least 150 kg, in particular at least 200 kg of a silicon starting material.

The feeder 10 also has a conveyor unit, which is a conveyor belt 13 and a pouring tube 20 includes. Between the conveyor belt 13 and the pouring tube 20 can, as in the embodiments according to 1 and 2 represented, a chute 17 be arranged. Instead of the chute 20 can be provided that the conveyor belt 13 slidable, in particular horizontally displaceable, to the starting material from the reservoir 11 into the pouring tube 20 to promote.

The conveyor belt 13 is below the reservoir 11 arranged and at least partially forms a floor for the reservoir 11 , The storage tank 11 also has a discharge opening 12 on, through which the starting material the reservoir 11 can leave. Below the conveyor belt 13 is a dust deposit 14 arranged.

The bulk tube 20 is shaped like a hollow cylinder. In an upper section of the bulk tube 20 is a holding tube 21 arranged, which is the pour tube 20 partially surrounded. The holding tube 21 can with the pour tube 20 be firmly connected. The holding tube 21 includes a circumferential stop 22 whose function will be explained later.

The bulk tube 20 further includes a valve, wherein the valve is a valve piston 24 includes. In particular, the valve is on the one hand by the valve piston 24 and on the other hand through the pouring tube 20 formed, wherein the valve piston 24 a lower end of the pouring tube 20 closes. The valve piston 24 preferably has a conical shape or is cone-shaped. The valve piston 24 includes insulation 26 , which may be formed of one or more insulating plates, which are centrally within the valve piston 24 are arranged.

The conveyor unit of the feeder 10 has a lifting device 30 on that with the pour tube 20 connected is. The lifting device 30 includes a winch 31 and a rope 32 , The rope 32 is with a valve stem 25 of the valve piston 24 firmly connected. The valve rod 25 is fixed to the valve piston 24 connected or integrally goes into the valve piston 24 above. The valve rod 25 preferably extends centrally or concentrically through the bulk tube 20 , Specifically, the pouring tube has 20 according to 1 and 2 a protective tube 23 on, centrally within the bulk tube 20 runs and a guide for the valve piston 24 forms. The lifting device 30 can measuring elements 33 include that with the winch 31 are coupled. The measuring elements 33 are preferably adjusted to the weight of the spill tube 20 capture.

In the embodiment according to 1 and 2 the conveyor unit has a chute 17 on that between the conveyor belt 13 and the pouring tube 20 is arranged. The chute 17 is preferably articulated and pivotable from a transport position into a bulk position. In the transport position is the chute 17 worked upwards, as in 1 recognizable. In the pouring position is the chute 17 folded down so that the starting material from the conveyor belt 13 over the chute 17 into the pouring tube 20 can slide ( 2 ).

Instead of the chute 20 can be provided that the conveyor belt 13 slidable, in particular horizontally displaceable, to the starting material from the reservoir 11 into the pouring tube 20 to promote.

The feeder 10 includes a housing 15 that the storage containers 11 , the conveyor unit with the conveyor belt 13 , the chute 17 and the pouring tube 20 as well as the lifting device 30 encloses fluid-tight. The housing 15 has a housing bottom 16 in which an opening 18 is arranged. The opening 18 includes a fluid-tight seal. The opening is concrete 18 below the bulk tube 20 arranged. The size of the opening 18 is adapted so that the pouring tube 20 through the opening 18 can be passed. The fluid-tight seal seals against the bulk tube 20 from.

The feeder 10 essentially has several operating states. On the one hand, the feeder 10 have a transport state in 1 is shown. On the other hand, it is provided that the feeding device 10 a filling state, which is exemplified in 2 is shown. In the transport state according to 1 is the bulk tube 20 through the lifting device 30 raised so that the bulk tube 20 completely inside the case 15 is arranged. The feeder 10 This makes it particularly compact and portable. In particular, the feed device from a filling station, in which the reservoir 11 is filled with silicon raw material, to a process chamber (not shown) to be transported. In the delivery state according to 2 is the bulk tube 20 lowered, leaving part of the pouring tube 20 out of the case 15 protrudes. The bulk tube 20 occurs through the opening 18 in the case back 16 therethrough. The bulk tube 20 can be lowered into a draw kettle of a process chamber so that silicon feedstock via the pour tube 20 can be performed directly to the crucible of the process chamber.

The structure of the feeder 10 is in the 5 and 6 again clarified. In particular, in the perspective view according to 5 recognizable that the housing 15 also a refill opening 19 may have, which is above the reservoir 11 is arranged. About the refill opening 19 can silicon source material in the reservoir 11 be refilled. Furthermore, it can be seen that the lifting device 30 outside the case 15 arranged and fluid-tight with the housing 15 can be connected.

The embodiment according to 5 and 6 shows a conveyor unit, in which instead of a conveyor belt 13 a roller conveyor 13 ' has provided. In 6 is also clearly visible that the reservoir 11 is preferably funnel-shaped. This facilitates the feeding of the starting material to the conveyor belt 13 or to the roller conveyor 13 ' , The feeder 10 can also have a gas connection 27 have, in the housing 15 is integrated. Specifically, the housing faces 15 the fluid connection 27 on. Through the fluid connection 27 can the case 15 be connected to a vacuum suction and / or a gas supply line. That way, inside the case 15 a process environment with inert gas, such as argon, and the required pressure, for example, a few millibars are generated.

Preferably, all components of the system according to the invention, in particular the feed device 10 which come into contact with the silicon source material, a ceramic material, for example silicon nitride or silicon carbide or silicon. This avoids contamination of the starting material.

The mode of operation of the system according to the invention is explained in more detail below:
The system according to the invention, in particular the feeding device 10 can be used on the one hand to fill the crucible before pulling a first single crystal. In particular, however, the invention is suitable for refilling the crucible prior to drawing a second or further single crystal from the same crucible.

After the first single crystal has been pulled out of the melt, it is lifted by a crystal lifting device into the lock chamber. Subsequently, a lock valve between the process chamber and lock chamber is closed and the pressure of the inert gas, preferably argon, increased in the lock chamber to the atmospheric pressure. Thereafter, the lock chamber can be separated from the process chamber with the lock valve. Subsequently, the bottom opening of the lock chamber is closed to prevent thermal shock, and the lock chamber removed. The single crystal produced cools down further in the lock chamber.

Immediately after the removal of the lock chamber from the process chamber or the furnace boiler, the feed system according to the invention, in particular the feed device 10 , which is already loaded with the required amount of the starting material, connected to the inlet opening of the furnace boiler or the process chamber. Furthermore, the feed system or the feed device 10 connected to supply connections, in particular electrical connections, gas connections and / or vacuum connections. The gas pressure of argon in the housing 15 is adjusted to the gas pressure in the melting chamber. Once the gas pressure of argon in the housing 15 is adapted to the gas pressure in the melting chamber, the fluid-tight, in particular vacuum-capable, lock valve of the drawing system or the process chamber is opened. Previously, any existing closure or valve of the opening 18 in the case back 16 open. The system is thus ready for the filling of the crucible.

In principle, the filling of the crucible or the feeding of the starting material to the crucible can be carried out with the system according to the invention in two different modes. In the so-called batch mode, the bulk tube 20 initially lowered into the feed position. Also the chute 17 tilted or pivoted to the feed position. Further, the conveyor belt 13 put into operation to the bulk tube 20 to fill with the starting material ( 3 ). The bulk tube 20 can be partially or fully filled with starting material. Through the measuring elements 33 becomes the weight of the starting material in the bulk tube 20 detected. The measuring elements 33 are preferably coupled to a controller, which is also connected to the conveyor belt 13 or the roller conveyor 13 ' , the chute 17 and the winch 31 is signal-connected. By an actual-target comparison can be calculated the desired amount of the starting material in the bulk tube 20 be set and controlled.

Once the desired level of the starting material in the bulk tube 20 is achieved, the rotation of the conveyor belt 13 or the roller conveyor 13 ' stopped and the pour tube 20 further lowered until the lower opening of the bulk tube 20 just above the crucible is located or the stop 22 of the holding ear 21 on the case back 16 rests. Preferably, the length of the bulk tube 20 or the distance between the stop 22 and the lower opening of the bulk tube 20 such that the pouring tube 20 is placed above the crucible in the correct position when the stop 22 at the bottom of the case 16 strikes. The bulk tube 20 is during the lowering by the cone-shaped valve piston 24 held. Specifically, it is provided that the valve piston 24 has a cross-sectional diameter which is greater than the inner diameter of the bulk tube 20 is. The bulk tube 20 is thus on the valve piston 24 on.

As soon as the stop 22 on the case back 16 rests, is a downward movement of the bulk tube 20 blocked. By further operation of the winch 31 the lifting device 30 will the plunger 24 lowered further, leaving the valve of the bulk tube 20 opens or the lower opening of the bulk tube 20 is released. Between the valve piston 24 and the pouring tube 20 thus creates a gap. The size of the gap is by appropriate lowering of the valve piston 24 chosen so that the starting material can escape. Preferably, the system according to the invention is suitable for supplying splinter- or pebble-like polysilicon with particle dimensions of up to 70 mm to a crucible.

By adjusting the size of the gap between the valve piston 24 and the pouring tube 20 For example, the feed rate of the feedstock into the crucible can be controlled. Simultaneously with the feeding of the starting material into the crucible, the temperature of the crucible is advantageously increased in order to melt the starting material.

Once in the pouring tube 20 arranged starting material is completely fed into the crucible, the winch 31 operated in the opposite direction, so first the valve piston 24 and then the bulk tube 20 through the valve piston 24 is raised until the top opening of the bulk tube 20 directly below the lowered chute 17 is arranged. The bulk tube 20 can now be filled with starting material again. Then the bulk tube 20 lowered again to fill the crucible. This process can be repeated until the desired amount of silicon melt is arranged in the crucible. Then the bulk tube 20 completely in the case 15 lifted and closed the lock valve of the process chamber. The feeder 10 can then be removed from the process chamber.

As an alternative to batch mode, the feeder can 10 also be operated in a continuous refill mode. It is envisaged that the holding tube 21 at a height of the bulk tube 20 is arranged such that the upper opening of the bulk tube 20 in fully lowered position of the pouring tube 20 directly below the chute 17 is arranged. This variant is in 4 shown. Specifically, it is envisaged that the pouring tube 20 has a greater length for the continuous refill mode than for the batch mode. The length of the bulk tube 20 is dimensioned such that the upper end of the bulk tube 20 just below the chute 17 is arranged when the stop 22 at the bottom of the case 16 strikes. By further lowering the valve piston 24 and thus opening the bulkhead valve and simultaneous operation of the conveyor belt 13 or the roller conveyor 13 ' Starting material is fed to the crucible continuously. The gap between the valve piston 24 and the pouring tube 20 is preferably adjusted so that a laminar feed stream of the starting material is achieved. Specifically, the gap is preferably set so as to prevent the supply current from being blocked.

By appropriate adjustment of the conveyor belt speed and the temperature of the crucible, the feed rate can be controlled. The feed of the starting material is preferably stopped when the complete starting material from the reservoir 11 is fed to the crucible. If necessary, the supply of the starting material can also meanwhile by switching off the conveyor belt 13 or the roller conveyor 13 ' and closing the valve of the bulk tube 20 being stopped.

Once the crucible has been filled, the bulk tube becomes 20 in the case 15 withdrawn. The sluice valve of the drawing system or the process chamber is closed and the gas pressure in the feeder 10 is raised to the atmospheric pressure. Subsequently, the feeder 10 Disconnected from the supply terminals and disconnected from the process chamber.

Once the pre-fabricated single crystal arranged in the uncoupled lock chamber has cooled, the single crystal can be removed from the lock chamber and the lock chamber can be reconnected to the furnace chamber or process chamber. The gas pressure of the argon between the process chamber and the lock chamber is adjusted and the vacuum valve between the lock chamber and the furnace chamber is opened. The drawing system is thus ready for the production of the next single crystal.

The procedure for feeding the starting material into the crucible can be repeated several times. The number of repetitions depends in particular on how many crystals are to be produced. Furthermore, the number of repetitions depends on the service life of the crucible.

In general, the amount of starting material that is in the reservoir 11 is calculated on the basis of technological requirements. The system according to the invention allows the absorption of 200 kg and more of the silicon starting material in the reservoir 11 , The starting material preferably comprises pure polysilicon, remelted silicon or a mixture thereof, wherein the dimensions of the particles of the starting material may be up to 70 mm. The starting material may further comprise a dopant.

• – Die Erfindung stellt ein bewegliches, modulares System bereit, das nur in dem Zeitfenster für das Zuführen des Ausgangsmaterials in den Schmelztiegel mit dem Ziehschacht bzw. der Schmelzkammer verbunden werden muss. Das erfindungsgemäße System kann somit mehrere Schmelzkammern mit Ausgangsmaterial beschicken.
• – Das erfindungsgemäße System ermöglicht die Wiederbefüllung eines Schmelztiegels während ein bereits erzeugter Einkristall in der Formenkammer abkühlt.
• – Das erfindungsgemäße System ist geeignet, um relativ große Mengen von Silizium von bis zu 200 kg und mehr in einem Wiederbefüllungsschritt dem Schmelztiegel zuzuführen, wobei eine relativ hohe Zuführgeschwindigkeit von bis zu 40 kg/Std. erreicht wird.
• – Das erfindungsgemäße System ist nicht nur für granuläres Ausgangsmaterial mit kleinen Korngrößen, sondern insbesondere für große splitter- oder brockenartige Einheiten mit Teilchenabmessungen von bis zu 70 mm geeignet.
• – Die Verwendung von großkörnigem Ausgangsmaterial ermöglicht adäquates Reinigen bzw. Ätzen des Ausgangsmaterials, um eine möglichst hohe Oberflächenreinheit zu erreichen und somit eine hohe Qualität der hergestellten Einkristalle sicherzustellen. Das erfindungsgemäße System ermöglicht also die Herstellung qualitativ besonders hochwertiger Silizium-Einkristalle.

Compared with known feed systems, the system according to the invention, at least in certain embodiments, has the following advantages:

• The invention provides a movable, modular system which only has to be connected to the draw tube or melting chamber in the time window for feeding the starting material into the crucible. The system according to the invention can thus feed a plurality of melt chambers with starting material.
• - The system according to the invention allows the refilling of a crucible while a single crystal already produced in the mold chamber cools.
• The system according to the invention is suitable for feeding relatively large amounts of silicon of up to 200 kg and more in one refilling step to the crucible, a relatively high feed rate of up to 40 kg / h. is reached.
• The system according to the invention is suitable not only for granular starting material with small particle sizes, but especially for large fragmentary or pebble-like units with particle dimensions of up to 70 mm.
• - The use of large-grained starting material allows adequate cleaning or etching of the starting material in order to achieve the highest possible surface purity and thus ensure a high quality of the single crystals produced. The system according to the invention thus makes it possible to produce particularly high-quality silicon monocrystals.

Within the scope of expert action, further refinements and embodiments of the method and apparatus described here by way of example only arise.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 6896732 B2 [0002, 0005, 0005]
• DE 60013594 T2 [0005]
• US 2003/0159647 A1 [0005]

Claims (11)

System for feeding a starting material into a melt for producing a monocrystalline material with a feed device ( 10 ) containing a reservoir ( 11 ) for the starting material and a conveying unit for conveying the starting material from the reservoir ( 11 ) in a crucible, wherein the feed unit a bulk tube ( 20 ), wherein the conveyor unit comprises a lifting device ( 30 ) for the pouring tube ( 20 ) comprises such that the feeding device ( 10 ) mobile, in particular assignable to several crucibles, is. A system according to claim 1, wherein the feeder means ( 10 ) a fluid-tight housing ( 15 ) having. A system according to claim 2, wherein the housing ( 15 ) comprises at least one gas connection and / or a vacuum connection. A system according to claim 2 or 3, wherein the housing ( 15 ) an opening ( 18 ) for the pouring tube ( 20 ), wherein the opening ( 18 ) comprises a fluid-tight, in particular vacuum-capable, closure. System according to one of claims 1 to 4, wherein the pouring tube ( 20 ) a valve with a conical valve piston ( 24 ) having. System according to one of claims 1 to 5, wherein the conveyor unit a conveyor belt ( 13 ) and / or a roller conveyor 13 ' comprising, between the reservoir ( 11 ) and the pouring tube ( 20 ) is arranged. System according to claim 6, wherein between the conveyor belt ( 13 ) and the pouring tube ( 20 ) a chute ( 17 ) is arranged. System according to one of claims 1 to 7, wherein the storage container ( 11 ) is adapted to receive a mass of the starting material of at least 100 kg, in particular at least 150 kg and / or at most 200 kg. System according to one of claims 1 to 8, wherein the lifting device ( 30 ) a winch ( 31 ) with a rope connected to the pouring tube ( 20 ) and / or the valve piston ( 24 ) connected is. System according to claim 9, wherein the lifting device ( 30 ) has an electric motor with the winch ( 31 ) is operatively connected. A process for producing a monocrystalline material by feeding a starting material into a melt, wherein a system according to claim 1 provided and fluid-tight with a furnace boiler, in particular vacuum-capable connected, and a predetermined amount of the starting material through the bulk tube ( 20 ) is conveyed into the crucible.

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