WO2012031776A1

WO2012031776A1 - Method and device for producing silicon

Info

Publication number: WO2012031776A1
Application number: PCT/EP2011/004559
Authority: WO
Inventors: Frank Grundmann; Stefan Hussy
Original assignee: Centrotherm Sitec Gmbh
Priority date: 2010-09-10
Filing date: 2011-09-09
Publication date: 2012-03-15
Also published as: DE202011105585U1; DE102010045040A1

Abstract

The invention relates to a method and a device for producing silicon, in particular a method and a device for producing a silicon ingot. In the method for producing silicon, the following steps are provided: introducing a processing gas containing silanes into a processing chamber; heating at least one first actively heatable element that lies within the processing chamber by means of resistance heating or a heating element that lies within the first element to a first temperature that lies in a temperature range in which silicon is deposited on the at least one element from the processing gas in order to form a silicon layer on said element; heating at least one second passively heatable element that lies adjacent to the at least one first element within the processing chamber by means of the at least one first element to a first temperature that lies in a temperature range in which silicon is deposited on the at least one second element from the processing gas in order to form a silicon layer on said second element; subsequently heating the at least one first element, the at least one second element, and/or the silicon layers that are formed on said elements to a second higher temperature that lies in a temperature range in which the silicon layer at least partially melts and flows out from the at least one first and second element in liquid form; and collecting the liquid silicon. The device for producing silicon has the following: at least one first processing chamber; at least one first actively heatable element that lies in the processing chamber; at least one controllable heating device that is suitable for actively heating the at least one first element by means of resistance heating or a heating unit that lies within the first element to first and/or second temperatures, wherein the first temperature lies in a temperature range in which silicon can be deposited on the at least one element from a processing gas containing silanes in order to form a silicon layer on said element, and the second temperature lies in a temperature range in which a silicon layer that is formed on the at least one element at least partially melts and flows out from the at least one element in liquid form; at least one second passively heatable element that lies adjacent to the at least one first element in the processing chamber, said second element being heatable by the first element to the first and/or second temperature; and at least one arrangement for the controlled collection and/or discharge of liquid silicon that flows out from the at least one element.

Description

METHOD AND DEVICE FOR PRODUCING SILICON

The present invention relates to a method and a device for producing silicon, in particular a method and a device for producing a silicon ingot.

It is known in semiconductor technology and photovoltaics to produce silicon rods with a high purity, for example according to the Siemens process, in deposition reactors, which are also referred to as CVD reactors. For this purpose, silicon thin rods are first taken in the reactors, on which silicon is then deposited during a deposition process in order to produce thicker silicon rods. These silicon rods are then cooled and fed to other processes. For subsequent processes, the silicon rods are usually at least partially comminuted in order to obtain silicon fragments and then these silicon fragments are in turn melted for further processing of the silicon. Such further processing is, for example, the drawing of silicon monocrystals from a silicon melt. Another process, for example, envisages the melting of the silicon fragments in a crucible, followed by a directional solidification in the crucible. Prior to melting of the silicon fragments, they are usually subjected to a surface cleaning step by etching to prevent impurities in a silicon melt.

A problem with the CVD deposition process is the so-called popcorn formation, ie the formation of air bubbles during film formation, since the CVD deposition process forms more or less porous silicon depending on the chamber pressure, the gas composition and the deposition temperature. Such air Inclusions arise especially at high growth rates, so that the growth rates must be reduced. In fact, such popcorn formation could otherwise lead to an etching step in which the etching liquid settles in the structures formed by popcorn formation, which can lead to impurities in the silicon melt. Therefore, in the CVD deposition process, the growth rate must be controlled. In the above operations, each of the silicon ingots after being formed in the CVD reactor is first cooled, and the rods are then removed and broken, followed by heating the silicon rods or fragments thereof to produce a silicon melt. This requires a very high energy consumption, since the silicon mass is first cooled and then heated again.

Moreover, the silicon thin rods required for deposition are very expensive for the CVD reactors, and the deposition is relatively slow in the first few hours since only a small mass separation is possible because of the small diameter of the thin rods. Also, ignition of the silicon thin rods within the CVD reactor is cumbersome due to the inherent properties of silicon. Based on the above processes, the present invention is therefore based on the object of providing a method and an apparatus for producing silicon, which overcomes at least one of the above-mentioned problems. According to the invention, a method for producing silicon according to claim 1 or 13 and an apparatus for producing silicon according to claim 14 or 34 is provided. Further embodiments of the invention will become apparent from the respective dependent claims. In particular, the method for producing silicon in a process chamber comprises the steps of: introducing a process gas containing silane into the process chamber, heating at least one within the process chamber Process chamber arranged first actively heated element by means of resistance heating or by means of a lying within the first element heating unit to a first temperature, which is in a temperature range at which deposits from the process gas silicon on the at least one element to form a silicon layer thereon, the heating at least one second, passively heatable element arranged within the process chamber adjacent to the at least one first element, through the at least one first element to a first temperature which is in a temperature range at which silicon is deposited on the at least one second element from the process gas, to form a silicon layer thereon; then heating the at least one first element, the at least one second element, and / or the silicon layer formed thereon to a second, higher temperature that is within a temperature range at which the silicon layer at least partially melts and from the at least one first and second element draining off in liquid form, and collecting the liquid silicon. Such a method allows the formation of silicon on an element and the conversion of the silicon thus formed without an intermediate cooling directly into a liquid state in which it can be fed to further processing. During layer growth, very high growth rates can be set since the quality of the silicon layer, for example with regard to popcorn formation, has no influence on the finally collected liquid silicon. It can be dispensed with the use of expensive silicon thin rods, which also the associated ignition problems can not occur. By providing second, passively heatable elements adjacent to the first, actively heatable elements, the surface available for deposition can be increased in a simple manner without the need for additional heating elements.

Preferably, before heating the at least one first element, the at least one second element and / or the silicon layer formed thereon, the process gas is exchanged to the second temperature by a gas which does not introduce impurities into the silicon layer or the formed silicon layer. introducing liquid silicon. In particular, the gas may be an inert gas. In this way, on the one hand, a controlled termination of the layer growth is achieved, and on the other hand prevents process gas optionally together with the liquid silicon exits the process chamber.

Although layer formation can take place even at pressures of less than 4 bar, the pressure in the process chamber is preferably kept at between 4 bar and 6 to 7 bar during the layer formation and the pressure during the melting of the silicon layer to a pressure below one bar, in particular in Be - rich of 600 mbar.

In a particularly preferred embodiment, the liquid silicon is collected in a crucible and then cooled controlled to achieve a directional solidification of the silicon. This results in a particularly advantageous combination of a CVD silicon growth process and a crystallization process, in which the silicon once formed can be maintained at a high temperature level without an intermediate cooling. As a result, the energy consumption and the time required for the production of a directionally solidified silicon block can be significantly reduced.

Preferably, at least one crucible is arranged below the at least one first and / or second element such that at least part of the effluent silicon flows directly into the crucible, ie, without contact with other elements. As a result, impurities in the melt in the crucible can be reduced to a minimum. Preferably, prior to receiving the liquid silicon, the crucible is heated to a temperature at or above the melting point of the silicon to avoid thermal shock between the liquid silicon and the crucible. In particular, it can be achieved that the silicon is not immediately cooled by contact with the crucible and solid, so that a subsequent directional solidification is possible. In one embodiment of the invention, prior to the melting of the silicon layer, a partition wall of the process space is opened to a space receiving the crucible, so that the process space only requires the space volume required for silicon growth, while the crucible can be arranged in a space adjacent thereto.

According to one embodiment of the invention, the at least one element is heated to the first and / or the second temperature by means of resistance heating. Preferably, the at least one second element surrounds the at least one first element radially and the silane-containing process gas is in each case introduced into a space formed between the at least one first element and the at least one second element. This makes it possible to obtain a good flow of the process gases within the process space, in particular a flow directed at least in the deposition areas.

It is also possible for the silicon layer to be heated at least partially to the first and / or second temperature via a heating device provided separately from the at least one first element. The heating via such a separate heating device is advantageous, in particular, when heating to the second temperature, since the silicon layer then melts away from the outside and a sudden slipping of the silicon layer from the at least one first element is prevented.

Preferably, after an at least partial melting of the silicon layer, the at least one first element, the at least one second element and / or the silicon layer still on it are brought back to the first temperature to re-deposit a silicon layer from a corresponding silane-containing process gas provided on the at least one element, which is subsequently melted again by a corresponding increase in temperature, wherein the resulting liquid silicon is collected again. This allows a continuous process that oscillates between silicon growth and melting to be achieved without the Process room must ever cool to ambient temperature. Such cooling is only required if the at least one first element and / or the at least one second element, for example, is working incorrectly or needs to be replaced.

Preferably, during a silicon deposition cycle, in each case an amount of silicon is deposited which is sufficient to substantially completely fill a corresponding crucible by the resulting liquid silicon. The amount of silicon formed can be controlled by various process parameters, such as the amount of process gas introduced, a layer thickness measurement of the silicon layer formed on the at least one element, etc.

An alternative method, which may also be performed in combination with the above method steps, comprises the steps of: introducing a process gas containing silane into the process chamber, heating at least one element disposed within the process chamber to a first temperature that is in a temperature range in which silicon is deposited on the at least one element from the process gas in order to form a silicon layer thereon, then heating the at least one element and / or the silicon layer formed thereon to a second, higher temperature, which lies in a temperature range wherein the silicon layer at least partially melts and from which at least one element flows off in liquid form, collecting the liquid silicon in a crucible heated to a temperature above the melting point of silicon and cooling the silicon collected in the crucible to e Ine directed solidification of silicon to achieve. The advantages of this method will be apparent from the aforementioned. The device for producing silicon has at least one first process chamber, at least one first, actively heatable element arranged in the process chamber, and at least one controllable heating device, which it is suitable to actively heat the at least one first element to first and / or second temperatures by means of resistance heating or by means of a heating unit located within the first element. The first temperature is in a temperature range at which silicon from a silane-containing process gas can deposit on the at least one element in order to form a silicon layer thereon. The second temperature is in a temperature range at which a silicon layer formed on the at least one element at least partially melts and flows away from the at least one element in liquid form. Adjacent to the at least one first element, at least one second, passively heatable element is arranged in the process chamber, which can be heated by the first element to the first and / or second temperature. Furthermore, at least one arrangement is provided for the controlled collection and / or discharge of liquid silicon which flows away from the at least one element.

Such a device enables a continuous silicon manufacturing process that can switch back and forth between film formation and melting of the formed film. The advantages of such a process are already outlined above. The at least one second element makes it possible to change the surface available for deposition without changing the heating geometry or the at least one first element. Thus, there is an arrangement of actively heated (by own resistance heating or inside opposite the process chamber insulated heating elements) heatable elements as well as passive (heated by the actively heated elements) heated elements. The passively heated elements offer high degrees of freedom in terms of the geometry used, since they do not require any connections for heating.

Preferably, the at least one first and second element is held in the process chamber such that below the at least one first and second element, a substantially free space is formed, into which the silicon can flow freely from the at least one first and second element. there For example, the at least one first element can preferably be suspended freely hanging from a ceiling of the process chamber. This results in a simple construction of the process chamber. In one embodiment of the invention, the at least one first element has an electrically conductive base element which is connected to a power supply in order to heat the base element via a resistance heating effect. This results in a simple, combined structure in which the at least one first element itself forms part of the at least one controllable heating device. In this case, the base element can preferably consist of graphite or CFC and have an optional nitride coating, in particular a silicon nitride coating. Both graphite and CFC allow high temperatures to be achieved through resistance heating, and the optional nitride coating allows for proper silicon deposition without the risk of silicon contamination. At the same time, the coating provides electrical insulation to the base, so that the resistance heating effect is not affected by the growing silicon layer. Furthermore, SiC formation on the base member is prevented. A defect of the coating can be easily determined by a change in the resistance value of the base element during a layer growth.

In an alternative embodiment, the at least one first element has a silicon nitride element or a base element with a silicon nitride coating, which has a cavity for accommodating a heating device, in particular in the form of a resistance heating element and / or a heating lamp. In this construction of the at least one first element, different heating devices can be used, which in particular can be isolated from the process environment via the at least one first element.

The at least one second element preferably surrounds the at least one first element radially, so that a flow space is formed between the elements. it becomes. The device further comprises at least one gas feed, which is suitable for introducing a silane-containing process gas directly into each flow space formed between the elements. In this way, a good and directed flow of the process gas in contact with the surfaces available for a separation can be achieved. Furthermore, thermal isolation between the at least one first element and a side wall of the process chamber is provided by the at least one second element, since heat radiated from the at least one first element can no longer directly reach the side wall. This can save considerable costs for the cooling of the side walls.

In a preferred embodiment, the at least one second element forms a honeycomb structure having a plurality of substantially vertically extending honeycombs, wherein at least one of the plurality of honeycombs formed in this way accommodates at least one of the first elements in each case. Such a honeycomb structure may be formed in one piece or by a plurality of individual plate elements. On the one hand, the honeycomb structure has high mechanical stability and, on the other hand, it also offers good space utilization of the available space. To relieve the ceiling of the process chamber, at least one support structure extending through the process chamber is preferably provided, which supports the at least one second element from below.

In one embodiment of the invention, the at least one first element has a rod shape with a diameter of preferably greater than four centimeters. A rod shape provides a good surface and flow around the at least one element with the process gas to allow a good film formation. The choice of a diameter of more than 4 cm allows a good layer structure from the beginning because of a larger surface area compared to silicon thin rods, which usually have a diameter of 2 cm or less. Of course, the diameter can be chosen to be even larger and optimized in particular for rapid growth. By choosing the diameter, the growth rate can be influenced because it is a surface deposition. As previously mentioned, popcorn formation at fast silicon growth is not detrimental to this type of device since the silicon formed directly melts and does not need to be cleaned prior to further processing.

In an alternative embodiment, the at least one first element has a plate shape. Preferably, a plurality of the first and second elements are provided to enable sufficient silicon growth within a growth cycle.

The at least one arrangement for the controlled collection and / or discharge of liquid silicon preferably has a crucible for receiving the liquid silicon, in which, for example, a further treatment of the silicon in the form of a directed solidification can be carried out directly. In this case, the crucible is preferably directly below the at least one first and / or second element placeable, that flows from the at least one first and / or second element effluent silicon directly into the crucible. As a result, the degree of contamination of the silicon melt formed in the crucible can be kept low.

In a preferred embodiment of the invention, at least one second heating device is provided for heating the crucible to a temperature at or above the melting point of silicon, so that the liquid silicon, when flowing into the crucible, does not solidify in an uncontrolled manner. In this case, the at least one second heating device is preferably controllable in order to be able to provide a controlled cooling of a silicon melt in the crucible in order, for example, to achieve directional solidification of the melt in the crucible from bottom to top. As a result, a silicon block, which is formed by directional solidification and can be used, for example, for photovoltaics, can be obtained in a simple and cost-effective manner. For a controlled cooling, at least one active cooling unit can also be provided, which is arranged in this way is that she can actively cool a pot. As a result, the process of directional solidification can be controlled advantageously.

The device may include a second process chamber that is separate from or separable from the first process chamber by a separator, wherein the pan may be disposed in the second process chamber. As a separation of the first and second process chamber, it is also considered, when the first and second process chambers communicate with each other via a pipeline, which can optionally be opened and / or closed. Of course, the opening / closing of the pipelines could also be effected by the solidification or melting of the silicon material passing through the pipelines. This makes it possible to provide different processes within the first and second process chambers, such as a layer growth in the first process chamber and a directional solidification in the second process chamber. In particular, a plurality of second process chambers may be provided, which are each supplied with silicon formed in the first process chamber, since the process of directional solidification may take longer than the silicon formation process. Preferably, at least one device is provided for setting a desired process atmosphere in the at least one process chamber in order to be able to advantageously set the respective process, such as, for example, the silicon deposition process and / or a directed solidification process. In one embodiment of the invention, the at least one arrangement for the controlled collection and / or discharge of liquid silicon comprises at least one liquid silicon pipeline connected to a bottom of the first process space and at least one heating device for heating the pipeline to a temperature at or above Melting temperature of silicon on. Such a pipeline allows the controlled discharge of liquid silicon even over longer distances in a corresponding receptacle, such as a crucible in a second process chamber. Due to the At least one heating device, the liquid silicon can be promoted over longer distances without the risk of solidification.

If the side walls are thermally insulated from the outer wall of the reactor, deposition of silicon can also take place on the side walls as soon as their temperature is above the deposition temperature of the silicon. In order to prevent too much silicon from accumulating on the side walls over time, the side walls must also be melted down in this case. This can be done, for example, that as soon as the deposited on the side walls of silicon exceeds a certain minimum thickness, the side walls are heated as far as the melting of the silicon from the rods on the rods or other devices for heating material, such as resistance heaters or radiant heaters in that the silicon deposited on the sidewalls also melts. If the silicon melted off the side walls is sufficiently pure, it can be conducted into a crucible for crystallization. If the purity of the silicon deposited on the wall is not sufficiently high, this material can be taken to the process after filling one of, for example, a plurality of crystallization containers in a further container which is introduced and introduced via a TCS synthesis. As a material for thermal insulation of the side walls, for example, offers a graphite felt. In order to obtain the highest possible purity of silicon depositing on the insulation, the insulation, such as, for example, the graphite felt, may have a coating, for example of silicon nitride, which does not introduce impurities into the silicon formed.

Preferably, all surfaces, the process chamber and associated elements which may come into contact with the process gas and / or the liquid silicon are each made of a material which does not generate significant impurities in the resulting silicon. An alternative device for producing silicon, which may additionally also have the abovementioned features, has the following: at least one first process chamber, at least one element arranged in the first process chamber, at least one controllable heating device which is suitable, the at least one element to heat to first and / or second temperatures, wherein the first temperature is in a temperature range at which silicon from a silane-containing process gas can deposit on the at least one element to form a silicon layer thereon, and wherein the second temperature in a temperature range in which a silicon layer formed on the at least one element at least partially melts and flows off from the at least one element in liquid form, at least one crucible for collecting liquid silicon that flows away from the at least one element, and at least one second Heizvorrichtu ng, which is controllable to heat the crucible to a temperature at or above the melting point of silicon in order to provide a controlled cooling of a silicon melt in the crucible and to achieve a directional solidification of the melt in the crucible from bottom to top.

The invention will be explained in more detail below with reference to the drawings. In the drawings shows:

Fig. 1 is a schematic sectional view through an apparatus for producing silicon;

Fig. 2 is a schematic sectional view through an alternative apparatus for producing silicon;

3 shows a schematic sectional view of a further embodiment of an apparatus for producing silicon;

Fig. 4 is a schematic detail view of deposition elements that may be included in the devices according to Figures 1 to 3; 5 is a schematic sectional view of an alternative deposition element which can be used in the devices according to FIGS. 1 to 3; ,

6 shows a schematic view from below of an arrangement of deposition elements which could be accommodated in the devices according to FIGS. 1 to 3;

Fig. 7 is a schematic partial sectional view through the arrangement of

Deposition elements according to FIG. 6.

Terms used in the following description, such as top, bottom, right, left, etc., refer to the illustration in the figures and are not limiting, although they may represent a preferred orientation. The term essentially should in each case comprise a deviation of not more than 5% or 5 °, preferably not more than 2% or 2 ° to the stated value.

Fig. 1 shows a schematic sectional view through an apparatus 1 for producing silicon. The device 1 has a housing 3, which forms a process chamber 4 in the interior. Gas connections 5 are provided on the housing 3, via which controlled gas can be introduced or discharged into the process chamber. In particular, an inert gas or a process gas, in particular a silane-containing process gas, such as trichlorosilane or monosilane, can be introduced into the process chamber 4 and discharged.

On a ceiling wall of the housing 3, a plate member is attached, which is hereinafter referred to as the deposition element 7. The deposition element 7 is made of a suitable material, which provides no or only insignificant impurities in the silicon in a silicon deposition process and which has a sufficient dimensional stability even at the required deposition temperatures. In addition, the plate material may consist of an electrically conductive material in order to allow it to be heated by means of its own resistance heater. In the illustrated embodiment, the deposition element 7 is designed as a graphite plate or a CFC plate element. which, for example, can each have a coating, in particular a silicon nitride coating. On the one hand, such a silicon nitride coating provides isolation of the base material from the process atmosphere. Furthermore, the coating also provides an electrical insulation against a silicon layer formed on the deposition element 7, which can be formed during a deposition process, as will be explained in more detail below.

Although only one deposition element 7 can be seen in FIG. 1, it should be noted that a plurality of such deposition elements 7 can be arranged perpendicular to the plane of the leaf of FIG.

The deposition elements 7 are respectively contacted via electrode units, not shown, such that a current flow through the deposition elements 7 for heating by means of resistance heating is possible.

Alternatively and / or additionally, it is also possible to provide within the process chamber one or more heating units, which can heat the deposition elements 7 or silicon layers formed thereon, for example, via thermal radiation to predetermined temperature ranges.

Below the deposition elements 7, a funnel element 10 is provided which extends from side walls of the process chamber 4 to an outlet opening 12 formed in the bottom of the process chamber 4. The funnel element 10 can be heated via a heating unit, not shown, to a temperature which is at or above a melting point of silicon.

At the bottom of the process chamber 4, an outlet opening 12 is provided which communicates with a piping system 14. The piping system 14 consists of two lines 16, which are mutually optionally connected via an actuating element 18 to the outlet 12 of the process chamber 4. The pipes 16 are each connected to a housing 23 in connection, in each case a chamber 24 is formed for receiving a crucible 26. In this case, the crucible 26 can be positioned in each case such that liquid emerging from the pipeline 16 into the chamber 24 reaches the crucible 26. The pipelines can be, for example, graphite tubes, which are surrounded on the outside by a thermal insulation and have a nitride coating on the inside. The graphite tubes could be heated via a corresponding electrical contact to temperatures above the melting point of silicon in order to allow a safe passage of liquid silicon. Alternatively, however, it would also be possible to provide an alternative heating unit in the region of the pipelines, and several pipelines could also be provided.

The housing 23 in each case has a loading / unloading opening for loading and unloading the crucible 26, which can be closed via a corresponding door element 28. In the region of the chamber 24, a heating unit, not shown, is provided, which is able to heat a pot 26 received therein to a temperature which is at or above a melting point of silicon. The heating unit may be constructed so that it can achieve a controlled cooling of a silicon melt accommodated in the crucible 26 in order, for example, to achieve a directed solidification from bottom to top within the crucible 26.

The operation of the device 1 will be explained in more detail below with reference to FIG. 1.

First, a process gas containing silane-containing process gas is introduced into the process chamber 4 via a process gas connection 5. Subsequently, the precipitation element 7 is heated to a temperature at which silicon is deposited on the deposition element 7 from the process gas containing silane. As a result, a growing silicon layer is formed on the deposition element 7. During this process, process gas is constantly fed via one of the connections 5, while the process gas is supplied via the other connection 5 is dissipated. This ensures that there is always sufficient silane-containing process gas available for the deposition process. In particular, it is possible to formally flow around the deposition elements 7 during the deposition process. When a sufficient thickness of the silicon layer is grown on the deposition element 7, the supply of the process gas containing silane is interrupted. By appropriate supply of an inert gas, such as hydrogen gas, the process gas can be completely flushed out of the process chamber 4. When this is done, the temperature of the deposition elements 7 and / or the silicon layer formed thereon is increased either by resistance heating of the deposition elements 7 and / or additional heating elements, not shown, to a temperature equal to or above the melting point the silicon layer is located. As a result, the silicon layer liquefies and begins to flow from the deposition element and drips onto the funnel element 10, which at this time is also heated to a temperature at or above the melting point of silicon. The dripping silicon thus flows through the funnel element 10 in the direction of the outlet opening 12 and here in the pipeline system 14. In this case, the control element 18 determines whether the liquid silicon continues to flow through the left or right-hand piping 16. At this point in time, the tubing 16 is also heated to a temperature that is at or above the melting point of silicon to ensure that the silicon remains in a flowable state and does not solidify. In the illustration according to FIG. 1, the adjusting element 18 is set such that liquid silicon would flow into the right-hand pipeline strand 16. The liquid silicon then passes from the pipeline 16 into the chamber 24 and flows into the crucible 26 accommodated therein. The layer thickness formed on the deposition elements 7 during the deposition phase can be chosen such that, when all of the silicon has melted, the crucible 26 reaches a desired degree of filling. When all of the silicon or a desired part of the deposition elements 7 has melted off, the temperature of the deposition elements 7 is reduced again and the gas atmosphere within the process chamber 4 can be changed from an inert gas atmosphere to a process gas atmosphere, so that a renewed silicon growth cycle can be initiated , At the same time, the liquid silicon received in the crucible 26 can be cooled to form a silicon ingot. In this case, the cooling can preferably be carried out in a controlled manner such that inside the crucible 26 a directional solidification takes place from bottom to top. Directed solidification preferably takes place in a noble gas atmosphere, such as in argon. Therefore, chamber 24 may need to be filled with the appropriate gas prior to directional solidification.

Again, when a sufficiently thick layer of silicon is formed on the precipitating elements 7, these silicon layers can again be melted therefrom according to the cycle described above, and the liquid silicon can be supplied, for example, to a next crucible 26 by, for example, positioning the actuator 18 within the piping system 14 is converted.

Thus, a continuous cycle of silicon growth, layer melting, and liquid silicon collection can be achieved.

Fig. 2 shows an alternative device 31 for the production of silicon. The device 31 has a housing 33, which forms a process chamber 34 in the interior. Gas connections 35 are provided in the housing 33, via which gases can be introduced into the process chamber 34 and discharged. In this case, for example, one of the gas connections 35 can be used for the introduction of gases, while the other is provided for the discharge of gases, as shown by the arrows in the region of the gas connections 35. In the illustration according to FIG. 2, the left-hand gas connection 35 is provided for the introduction of gases, while the right-hand gas connection 35 is provided for the discharge of gases. Of the left gas connection 35 is connected via corresponding supply lines with different gas sources in connection, in particular a gas source for a silane-containing process gas, such as trichlorosilane or monosilane. Furthermore, the left gas connection 35 is also connected to an inert gas source, for example a source of argon. Via a corresponding control unit, the process gas or the inert gas can be introduced into the process chamber 34.

The right-hand gas connection 35 communicates with a corresponding suction unit and can be connected to, for example, two different gas conditioning units, on the one hand a gas processing unit for process gas and on the other hand a gas conditioning unit for inert gas.

In an upper region of the process chamber 34, a plurality of Abscheidi- tion units 37 is provided which can be heated by suitable heating means to a temperature at which a silicon deposition can take place from a silane-containing process gas atmosphere, and which can also be heated to a temperature is at or above the melting point of silicon.

The deposition units 37 can have very different configurations for this purpose. In the illustration according to FIG. 2, the separation units 37 each have two rods 39 which extend downwardly from the ceiling of the process chamber 34 and which are connected to one another at their free, lower end via a bridge element 40. The rods 39 each consist of an electrically conductive material and are in electrically conductive relation to electrode units not shown in detail. The bridge member 40 is also made of an electrically conductive material and is connected in an electrically conductive relationship with the rods 39. A current flow through the rods 39 and the bridge element 40 of a deposition unit 37 can be initiated via the electrode arrangements (not shown) in order to heat them by means of resistance heating. In particular, a warming to the above Temperatures, on the one hand allow a silicon deposition and on the other hand allow a melting of silicon, take place.

The rods 39 and the bridge element can be made of graphite, for example, or be designed as CFC elements, in particular CFC tubular elements. Although the rods 39 and the bridge member 40 are shown as separate elements, they may also be integrally formed. The rods 39 and the bridge member 40 should preferably be made of a material that does not generate contaminants within a silicon growth process. This applies in particular to the parts of the respective elements exposed to the process chamber. The elements may each or together have a silicon nitride coating, which on the one hand forms an electrical insulation of the electrically conductive base material with respect to a silicon layer applied thereon and on the other hand also provides a mechanical shield, in order to prevent the electrically conductive base material from contaminating the surface Process of silicon layer formation brings.

It should be noted that the deposition unit 37 may also have a different structure.

Heightwise below the separation unit 37, a funnel-shaped downwardly tapering projection 42 is provided on side walls of the process chamber 34, which can be heated in a suitable manner via a corresponding heating unit to a temperature above the melting point of silicon.

Heightwise below the projection 42, a receiving space for a crucible 44 is provided, which is suitable for receiving liquid silicon. The crucible 44 is made of a suitable material which does not introduce impurities into a silicon melt accommodated therein. For example, the crucible 44 may be made of quartz and optionally may have a silicon nitride coating. Generally, it should be noted that all of the elements within the process chamber 34 have sufficient thermal stability to withstand the processes within the process chamber 34, and that at least the surfaces exposed to the process chamber 34 are each formed so as not to generate significant contaminants during a silicon growth process ,

In the region of the receptacle for the crucible 44, in turn, a corresponding heater, not shown, is provided, which is suitable for heating the crucible 44 to a temperature which is at or above a melting point of silicon. Laterally adjacent to the receiving area for the crucible 44 of the process chamber 34, a further chamber 46 is provided. This is connected via a corresponding opening 48 in a side wall of the housing 33 with the process chamber 34 in connection. This opening 48 can be closed via a corresponding door element 50 in order to be able to separate the process chamber 34 from the chamber 46.

In addition, a non-illustrated movement device for moving the crucible 44 from the process chamber 34 is provided in the chamber 46. In this case, the movement device is in particular also able to move the crucible 44 when it is filled with silicon. Although only one lateral chamber 46 is shown in FIG. 2, it should be understood that a plurality of these chambers 46 may communicate with the process chamber 34, each of which may be closed by corresponding door members.

In the area of the chamber 46, suitable heating and / or cooling devices may be provided, which allow a directional solidification of a silicon melt within the crucible 44 in a noble gas atmosphere, such as in argon.

The operation of the device 31 will be explained in more detail below with reference to FIG. 2. At the beginning of a process, a crucible 44 is located in the position shown in FIG. 2 within the process chamber 34. Via the left gas port 35, a process gas containing silanes, such as trichlorosilane or monosilane, is introduced into the process chamber 34, and the deposition units 37 are opened heats a temperature at which a silicon deposition takes place thereon. The process gas is introduced in such a way that it flows around the deposition units 37 as uniformly as possible, wherein in each case a predetermined amount of process gas is discharged via the right-hand gas connection 35 in order to provide a constant refreshment of process gas during the silicon deposition. The silicon deposition is continued until an amount of silicon has been deposited on the deposition units 37 sufficient to provide substantially complete filling of the crucible 44 with molten silicon material. Then, the process gas supply is stopped, and the process chamber 34 is purged with an inert gas such as hydrogen. Subsequently, the deposition units 37 and / or the silicon layers thereon are raised to a temperature which is at or above the melting temperature of silicon. As a result, the silicon layers melt and start to flow away from the deposition units 37. The effluent silicon flows into the crucible 44, and in part directly and partially over the funnel-shaped tapering projection 42. Both the crucible 44 and the projection 42 are heated at this time to a temperature at or above the

Melting point of silicon is to prevent premature solidification of the silicon melt. For controlled melting, the deposition units 37 can be heated to the melting temperature offset in time.

A silicon melt is formed within the crucible 44. When the silicon is melted off either completely or at least a sufficient amount from the deposition units 37 in order to achieve a desired degree of filling of the crucible 44, the temperature of the deposition units 37 is again reduced. This can be done by natural cooling, which can also be supported by an inert gas flow through the process chamber 34 therethrough. The filled as described above crucible 44 is then over the Opening 48 is transported with the door open 50 in the chamber 46 and it can be a new, empty crucible 44 are received in the process chamber 34. Thereafter, a process gas containing silane may again be introduced into the process chamber 34 to provide re-formation of silicon layers on the deposition elements 37, which in turn may be subsequently melted to receive a silicon melt in the new crucible 44.

The gas in chamber 46 can then be exchanged by filling the chamber 46 with inert gas, for example with argon. The filled crucible 44 in the chamber 46 may then be cooled to solidify the silicon melt therein. This can be done in a controlled manner such that within the crucible 44 a directed solidification takes place. Alternatively, however, uncontrolled solidification is also possible in order to produce a silicon block in the crucible 44, which can subsequently be further processed in a suitable manner. In particular, it is possible that a solidification of the silicon melt takes place within the chamber 46, and the crucible 44 is subsequently conveyed to a separate crystallization plant, in which the silicon material in the crucible 44 is remelted, in order subsequently to be cooled in a controlled manner, to provide directional solidification. This would have the advantage that the system shown in Fig. 2 can be used in combination with existing crystallization plants, wherein the crucible 44 can be filled in each case via the device 31 with a desired degree of filling.

It is possible that the crucible 44 is transported at a sufficiently high temperature to the crystallization plant in order to save energy during reflow of the silicon material in the crucible 44. Preferably, the crucible temperature is so high that the silicon melt in the crucible 44 is not completely solidified. In this case, a transport system could preferably be used which seals the crucible 44 in an inert gas atmosphere between the device 31 and a crystallization plant 31 (not shown) according to FIG. 2 transported, and passes to these. However, it is particularly preferred if the crystallization plant is formed directly in the region of the chamber 46, since then direct directing to the filling of the crucible 44, a directional solidification of the silicon melt formed therein can take place.

Fig. 3 shows a further alternative device 61 for the production of silicon.

The device 61 has a housing 63 which has a first upper process chamber 64 and a second, lower process chamber 65 inside. In the area of the upper process chamber 64, gas connections 66, such as the gas connections 5 or 35 described above, are provided. Furthermore, deposition elements 67 are again provided in the region of the upper process chamber 64. In the illustrated embodiment, the deposition elements 67 consist of a tube 68 which is closed at a lower end 69. The tube 68 is secured to the upper wall of the housing 66 at its upper, open end in a suitably sealed manner. Inside the tube 68, a heating element 70 is provided, via which the tube 68 can be heated from the inside. The heating element 70 may be, for example, a resistance heating element or else a heating lamp. The heating element is adapted to heat the tube 68 to a temperature at which silicon deposition occurs from a process gas atmosphere containing silanes. In addition, the heating unit 70 may also be capable of heating the tube to a temperature that is at or above a melting point of silicon. Alternatively, it is also possible to provide one or more further heating elements outside the tube 68 in the region of the upper process chamber 64, which can heat the tube and / or a silicon layer formed thereon to a temperature at or above the melting point of silicon.

The bottom of the upper process chamber 64 is formed by a funnel-shaped downwardly tapering wall member 72 having a central outlet opening 73. In the area of the lower process chamber 65, a crucible receptacle 74 for receiving a crucible 75 is provided. The crucible receptacle 74 can be designed as a heating and / or cooling unit to heat and / or cool a crucible 75 received thereon in a controlled manner. Of course, a cooling unit can also be provided under the crucible receptacle.

In the region of the lower process chamber 65, a side heater 76 is further provided, which at least partially radially surrounds the crucible 75. Although only one side heating element 76 is shown in FIG. 3, it should be noted that a plurality of such side heating elements 76, which may for example also be arranged one above the other, may be provided. In particular, it is also possible to provide a side heating element 76, which is arranged substantially above an upper edge of the crucible 75 in order to be able to heat a melt in the crucible 75 obliquely from above.

An upper surface of the lower process chamber 65 is formed by a wall member 78 having a central opening 79 aligned with the opening 73 in the wall member 72. The wall element 78 can be designed as a ceiling heater, or a ceiling heater adjacent to the wall element 78 could also be provided. In particular, the opening 79 may be slightly larger than the opening 73. Between the wall element 72 and the wall element 78, a slide 81 is provided, which can close a connection between the upper process chamber 64 and the lower process chamber 65. For this purpose, the slide 81 is laterally movable, as indicated in Fig. 3 by the double arrow in the slide 81. In this case, it is possible for the slide 81 to be of the type which can separate the upper and lower process chambers 64, 65 in a gas-tight manner. Instead of a slider 81, other closure mechanisms may be provided at this point. The operation of the device 61 will be explained in more detail below. In an initial situation, the slider 81 is in a closed position. In the region of the upper process chamber 64, a silane-containing process gas is introduced, and the deposition elements 67 are heated to a temperature at which deposition of silicon on the surface of the deposition elements 67 takes place. As a result, corresponding silicon layers are formed on the deposition elements 67. When sufficient silicon layer thickness is achieved, the process gas flow into the upper process chamber 64 is stopped, and the upper process chamber 64 is purged with an inert gas, such as hydrogen. Thereafter, the spool 81 is brought to an open position to establish communication between upper and lower process chambers 65 via the openings 73 and 79 in the wall members 72 and 78, respectively. Subsequently, the deposition elements 67 and / or the silicon layers thereon are heated to a temperature above the melting point of silicon, whereby the silicon layers melt. Molten silicon flows from the deposition elements 67 to the bottom wall member 72 of the process chamber 64, which at this time is heated to a temperature at or above the melting point of silicon. This ensures that the molten silicon remains in the liquid state and flows to the opening 73. The molten silicon then flows through the opening 73 and opening 79 into the lower process chamber 75 and flows directly into the crucible 75. When all of the silicon or sufficient amount of silicon has been melted away from the deposition elements 67 to provide a desired fill level of the crucible 75 reach, the slider 81 can again be moved to a closed position. It should be ensured that no more silicon flows in the direction of the opening 73 and then accumulates in this area. In the region of the lower process chamber 65, the silicon melt received in the crucible 75 is then cooled in a controlled manner in order to achieve directional solidification. For this purpose, the hydrogen can be replaced by a noble gas such as argon, so that the controlled directional solidification takes place in, for example, argon atmosphere.

Meanwhile, within the upper process chamber 64, a renewed silicon film formation process may be performed. Via the slide 81, it is possible for different process gas atmospheres to be set in the process chambers 64 and 65 with regard to the gas composition and the pressures prevailing there. Thus, for example, a silicon deposition is usually carried out at an elevated pressure above 4 bar and preferably in the range of about 6 bar, while a directional solidification usually takes place in an inert gas atmosphere at a pressure below 1 bar and in particular at 600 mbar. 4 shows an enlarged detail view of a deposition unit 90 which can be used, for example, in the region of a process chamber of the devices described above for producing silicon.

FIG. 4 shows at 91 an upper housing wall of a process chamber, which has feedthroughs 94.

The deposition unit 90 consists of a U-shaped base with two leg members 95 and a connector 96. The leg members 95 extend substantially parallel, and the distance therebetween is sized so that the leg members pass through two adjacent penetrations 94 in the upper process chamber wall 91 can be.

At their free end, the leg members 95 each have recesses 97 for receiving a contact pin 100 of an electrode unit 101. In this case, the recess 97 and the contact pin 100 are complementarily shaped so that therebetween a fixed mechanical connection, in particular a

Screw connection or a bayonet connection can be made.

The U-shaped base consists of an electrically conductive material, such as graphite or a CFC body, in which, for example, the

Leg members 95 and the connecting member 96 are formed as a hollow tube. The base body made of electrically conductive material is coated with a silicon coated ziumnitridschicht which covers at least all lying within a process chamber areas of the body. Preferably, all surfaces of the main body except the surfaces in the region of the recess 97 should have a corresponding coating.

The electrode units 101 each have the pin 100 connected to the leg elements 95, a plate element 103 and a further contact pin 106. The plate member 103 has a diameter larger than the diameter of the passages 94 in the housing wall 91. This makes it possible that the plate members 103 cover the respective passages 94 and are supported by a surface of the housing wall 91. As a result, the deposition member 90 can be supported in a drooping manner by the upper wall member 91 as a whole. The contact pin 106 serves for connection to a power supply. Although not shown separately, the plate members 103 may each be secured to the housing wall via respective fasteners, such as screws. The screws should be passed through the plate elements in an electrically insulated manner. In the region of the bushings 94, an electrically insulating sleeve element 108 is provided in each case. The sleeve member 108 is made of PTFE, for example. The sleeve member 108 has a sleeve portion which fits snugly in the bushings 94, and a parallel to the top of the housing wall 91 extending seal member. The sealing member is sized to be received between the plate member 103 and the top of the housing wall 91 and provides a seal therebetween. In the region of the passage 94, a thermal insulating element 110 is further provided, for example in the form of a graphite felt sleeve. The thermal insulating element is dimensioned such that it can be inserted between the electrical insulating element 108 and the part of the rod element 95 extending through the bushing 94. As can be seen in Fig. 4, the thermal insulating member 110 has a greater length than the length of the passage 94, and is after both above as well as below. In Fig. 4, electrical insulating members 112 are further provided adjacent to an inside of the housing wall 91. These insulating elements 112 may be provided in the form of PTFE mats, which cover the inside of the housing wall 91 substantially completely. Adjacent thereto, further thermal insulation elements 114 facing the process space, for example in the form of graphite felt mats 114, are provided. Shown at 116 is another electrical isolation member, which may be, for example, a fused silica member, separating the adjacent graphite felts mat between the leg members 95 to prevent electrical shorting therebetween. The graphite felt may have a coating of silicon nitride to provide better stability to the process gas atmosphere. Corresponding graphite felt mats may be provided substantially on all inner walls of a process chamber in order to better insulate them thermally. A deposition element 90, as shown in FIG. 4, may be employed in any of the silicon fabrication devices described above. In the embodiment according to FIG. 1, the plate elements 7 could be replaced by the deposition elements 90. And it would also be possible to replace the deposition elements 67, as shown in FIG. 3, by the deposition elements 90.

FIG. 5 shows another embodiment of a deposition element 120 carried by an upper housing wall 121 of a process chamber. The deposition element 120 has a tubular base body 124, at the upper end of which a support flange 126 is formed, and whose lower end is closed by a bottom 128. The tubular part of the base body 124 is dimensioned such that it fits through a corresponding passage in the upper housing wall 121 in such a way that an electrically and / or thermally insulating element can be accommodated therebetween. The support flange 126 is formed so that it is larger than the diameter of the passage in the housing wall 121st

The tubular base body can for example consist of graphite or CFC and have a silicon nitride coating.

Inside the tubular base body 124, a heating device 130 is provided, for example in the form of a resistance heating element or a heating lamp. In the area of implementation, suitable electrically and thermally insulating elements can again be provided. The deposition element 120 may in turn be used in any of the embodiments described above.

FIGS. 6 and 7 show an alternative arrangement of deposition elements which can be used in the devices according to FIGS. 1 to 3, FIG. 6 being a bottom view and FIG. 7 being a schematic partial sectional view of the arrangement according to FIG demonstrate.

In the view from below, a process chamber housing is diagrammatically indicated at 150, in which a plurality of first deposition elements 152 and a multiplicity of second deposition elements 154 are arranged.

As will be explained in more detail below with reference to FIG. 7, each of the plurality of first deposition elements 152 is an actively heated element. These first deposition elements can be designed, for example, as resistance heating elements and have the U-shaped structure according to FIG. 4. But they can also have a structure according to FIG. 5 with an internal heating element. As actively heated so an element is referred to, in which an outer deposition surface is heated from the inside.

The second deposition elements 154 are each passive heatable elements whose deposition surfaces can be heated from outside the element. The second deposition elements form a honeycomb structure having a plurality of honeycombs 156. The honeycombs 156 are symmetrically disposed about an inner honeycomb 156. The honeycomb 156 each extend substantially vertically in a corresponding process chamber. One of the first deposition elements 152 is disposed in the honeycomb 156, with the exception of the inner honeycomb 156. The walls of the respective honeycomb 156 surround the deposition elements in the radial direction.

In the view according to FIG. 7, which shows two adjacent honeycombs 156 according to FIG. 6 in section, a cover wall 160 of a process chamber housing, two gas inlet nozzles 162 as well as a carrier 164 for the honeycomb structure are also shown schematically.

In the illustration according to FIG. 7, the first deposition elements 152 each have a U-shaped structure, similar to the structure according to FIG. 4, and they are designed as resistance heating elements. By fixed to the top wall bracket 166 and connection bridges 168 more of the U-shaped deposition elements can be connected in series within a process chamber in order to reduce the number of passes through the top wall 162.

The second deposition elements 154 are each straight plate elements forming the honeycomb structure. But it is also possible that the honeycomb structure as a whole or individual of the honeycomb 156 or parts thereof are integrally formed. At least the inner surfaces of the honeycombs are made of a material which, in the case of silicon deposition, does not introduce impurities into the silicon, such as, for example, silicon nitride.

In the area of the top wall gas inlet nozzles 162 are further provided, one per honeycomb. These may extend through the top wall 162, as shown in FIG. 7, or they may also communicate with a common supply line connected via a single passage to a gas supply external to the process chamber. The Gas inlet nozzles may be directed vertically downwardly into the honeycombs, as indicated on the right in Fig. 7, or they may also be directed obliquely into the respective honeycomb structure, as indicated at the left in Fig. 7.

The carrier 164, of which only a portion is visible, extends substantially horizontally through the process chamber and may be supported on the sidewalls or a bottom thereof. The carrier 164 has any suitable structure suitable for supporting the honeycomb structure but at the same time allowing silicon to flow out of the honeycomb. At least the surfaces of the carrier 164 are of a material that does not introduce impurities into the silicon in a silicon deposition, such as silicon nitride.

In the layer growth cycles described above, it is possible for silicon to be deposited on chamber walls heated by the deposition elements and then melted. This silicon can either be fed to a crucible, or be discharged separately. But it is also possible to provide such a large chamber geometry that the walls are not warmed up sufficiently for a silicon deposition.

The invention has been explained in detail above with reference to some embodiments of the invention, without being limited to the specific embodiments shown. In particular, it should be noted that different elements of the respective embodiments can be freely combined with one another and / or exchanged for one another, provided that a corresponding compatibility exists.

Claims

claims

Method for producing silicon in a process chamber, comprising the following steps:

Introducing a silane-containing process gas into the process chamber; Heating at least one disposed within the process chamber first, actively heated element by means of resistance heating or by means of a lying within the first element heating element to a first temperature, which is in a temperature range at which separates from the process gas silicon on the at least one first element to to form a silicon layer thereon;

Heating at least one second, passively heatable element arranged within the process chamber adjacent to the at least one first element, through which at least one first element is at a first temperature which is in a temperature range at which silicon from the process gas is deposited on the at least one second element depositing to form a silicon layer thereon;

then heating the at least one first element, the second element and / or the silicon layer formed thereon to a second, higher temperature which is in a temperature range at which the silicon layer at least partially melts and of the at least one first and second element in liquid form flows; and

Collecting the liquid silicon. 2. The method of claim 1, wherein the process gas is exchanged prior to heating the at least one first element, the at least one second element and / or the silicon layer formed thereon to the second temperature by a gas which does not introduce impurities into the liquid silicon.

3. The method according to any one of the preceding claims, wherein the pressure in the process chamber during the layer formation is 4 to 7 bar and the pressure during the melting of the silicon layer is maintained at a pressure below 1 bar, in particular in the range of 600 mbar.

Method according to one of the preceding claims, wherein the liquid silicon is collected in a crucible and then cooled controlled to achieve a directional solidification of the silicon.

Method according to one of the preceding claims, wherein at least before the melting of the silicon layer, a crucible is arranged under the at least one first and / or second element such that the effluent silicon flows directly into the crucible.

The method of claim 4 or 5, wherein the crucible is heated to a temperature above the melting point of the silicon prior to receiving the liquid silicon.

Method according to one of claims 4 to 6, wherein prior to melting of the silicon layer, a partition wall of the process chamber is opened to a space receiving the crucible.

Method according to one of the preceding claims, wherein the at least one first element is heated by means of resistance heating to the first and / or the second temperature.

Method according to one of the preceding claims, wherein the at least one second element radially surrounds the at least one first element and the silane-containing process gas is in each case introduced into a space formed between the at least one first element and the at least one second element.

Method according to one of the preceding claims, wherein the silicon layer at least partially separated from the at least one first element provided heating device to the first and / or the second temperature is heated.

11. The method according to any one of the preceding claims, wherein after at least partial melting of the silicon layer, the at least one first element, the at least one second element and / or the silicon layer still on it is brought back to the first temperature, to re-deposition of a silicon layer from a corresponding silane-containing process gas provided on the at least one first and second element, which is subsequently melted again by a corresponding increase in temperature, wherein the resulting liquid silicon is in turn collected.

Method according to one of the preceding claims, wherein during a layer growth cycle, a sufficient amount of silicon is deposited in order to achieve a desired, in particular a high degree of filling within a crucible for receiving liquid silicon.

Introducing a silane-containing process gas into the process chamber; Heating at least one element disposed within the process chamber to a first temperature that is within a temperature range at which silicon is deposited on the at least one element from the process gas to form a silicon layer thereon;

then heating the at least one element and / or the silicon layer formed thereon to a second, higher temperature which is in a temperature range at which the silicon layer at least partially melts and from which at least one element flows off in liquid form;

Collecting the liquid silicon in a crucible heated to a temperature above the melting point of silicon; and Controlled cooling of the silicon collected in the crucible to achieve directional solidification of the silicon.

Apparatus for producing silicon comprising:

at least a first process chamber;

at least one first actively heatable element arranged in the process chamber;

at least one controllable heating device which is suitable for actively heating the at least one first element to first and / or second temperatures by means of resistance heating or by means of a heating unit located within the first element, wherein the first temperature lies in a temperature range at which silicon emerges from a Silane-containing process gas may deposit on the at least one element to form a silicon layer thereon, and wherein the second temperature is in a temperature range at which a formed on the at least one silicon layer at least partially melts and flows from the at least one element in liquid form ;

at least one in the process chamber adjacent to the at least one first element arranged second, passively heatable element which can be heated by the first element to the first and / or second temperature; and

at least one arrangement for the controlled collection and / or discharge of liquid silicon which flows away from the at least one element.

The apparatus for producing silicon according to claim 14, wherein the at least one element is held in the process chamber such that a free space is formed below the at least one element.

Apparatus for producing silicon according to claim 14 or 15, wherein said at least one first element is suspended from a ceiling of the process chamber. The apparatus for producing silicon according to any one of claims 14 to 16, wherein the at least one first element comprises an electrically conductive base connected to a power supply for heating the base via a resistance heating effect.

Device for producing silicon according to claim 17, characterized in that the base element consists of graphite or CFC and optionally a nitride coating in particular has a silicon nitride coating.

The device for producing silicon according to claim 14, wherein the at least one first element is a silicon nitride element or has a base element with a silicon nitride coating, which has a cavity for accommodating a heating device, in particular in the form of a resistance heating element and / or a heating lamp.

The device of claim 14, wherein the at least one second element radially surrounds the at least one first element such that a flow space is formed between the at least one first element and the at least one second element, and wherein the device comprises at least one gas feed. which is suitable for introducing a silane-containing process gas directly into each flow space formed between the at least one first element and the at least one second element.

The apparatus of any one of claims 14 to 20, wherein the at least one second comprises a honeycomb structure having a plurality of substantially vertically extending honeycombs, at least one of the plurality of honeycombs thus formed each receiving at least one of the first elements.

22. Device according to one of claims 14 to 21, which has a support structure extending through the process chamber, which supports the at least one second element from below.

23. An apparatus for producing silicon according to any one of claims 14 to

22, wherein the at least one first element has a rod shape with a diameter of greater than 4 cm.

24. An apparatus for producing silicon according to any one of claims 14 to

23, wherein the at least one first element has a plate shape.

25. An apparatus for producing silicon according to any one of claims 14 to

24, wherein a plurality of the respective first and second elements is provided.

26. An apparatus for producing silicon according to any one of claims 14 to

25, wherein the at least one arrangement for the controlled collection and / or discharge of liquid silicon has at least one crucible for receiving the liquid silicon.

27. The apparatus for producing silicon according to claim 26, wherein the crucible can be placed directly below the at least one first and / or second element in such a way that silicon draining from the at least one first and / or second element flows directly into the crucible.

28. An apparatus for producing silicon according to any one of claims 26 or 27, comprising at least a second heating means for heating the crucible to a temperature at or above the melting point of silicon.

29. An apparatus for producing silicon according to claim 28, wherein the at least one second heating device is controllable to provide a controlled discharge. Cooling to be able to provide a silicon melt in the crucible to achieve a directional solidification of the melt in the crucible from bottom to top.

30. An apparatus for producing silicon according to any one of claims 26 to

29, which has at least one active cooling unit arranged to actively cool a crucible.

31. An apparatus for producing silicon according to any one of claims 26 to

30, which has at least one second process chamber, which is separated from the first process chamber or can be separated therefrom by means of a separating element, wherein the crucible can be arranged in the second process chamber.

32. Apparatus for producing silicon according to any one of claims 26 to

31, which has at least one device for setting a desired process atmosphere in the at least one process chamber.

33. An apparatus for producing silicon according to any one of claims 26 to

32, wherein the at least one arrangement for the controlled collection and / or discharge of liquid silicon, at least one connected to a bottom of the first process chamber in liquid silicon pipeline and at least one heater for heating the pipe to a temperature at or above the melting temperature of Has silicon.

34. Apparatus for producing silicon, comprising:

at least a first process chamber;

at least one element disposed in the first process chamber;

at least one controllable heating device adapted to heat the at least one element to first and / or second temperatures, wherein the first temperature is in a temperature range at which silicon from a silane-containing process gas can deposit on the at least one element to form a silicon layer thereon, and wherein the second temperature is in a temperature range at which a formed on the at least one silicon layer at least partially melts and of the at least one element in liquid Form drains off;

at least one crucible for collecting liquid silicon flowing away from the at least one element; and

at least one second heater controllable to heat the crucible to a temperature at or above the melting point of silicon to provide controlled cooling of a silicon melt in the crucible and to directionally solidify the melt in the crucible from bottom to top to reach.

Apparatus according to claim 34, additionally comprising the features of at least one of claims 14 to 33.