WO2020001939A1

WO2020001939A1 - Method and device for drawing a single crystal of semiconductor material, and semiconductor wafer of silicon

Info

Publication number: WO2020001939A1
Application number: PCT/EP2019/064553
Authority: WO
Inventors: Dieter Knerer
Original assignee: Siltronic Ag
Priority date: 2018-06-25
Filing date: 2019-06-04
Publication date: 2020-01-02
Also published as: TW202001010A; DE102018210286A1; TWI707992B

Abstract

The invention relates to a method for drawing a single crystal (150) using a device (100) having a crucible, which device is used to draw the single crystal (150) from a melt in the crucible (130), wherein: a crucible consisting at least partially of a nitride of the semiconductor material is used as the crucible (130), and a partial pressure for nitrogen is set or adjusted to a value of at least 0.1 mbar in the device (100), and/or a cooling plate (121), which surrounds the crucible and in particular is annular, is provided at the height of the crucible (130), which cooling plate is in thermal contact with a cooling device (120), which surrounds the cooling plate (121) and the crucible (130), and/or on a surface (131) of the crucible facing the melt, crystal needles (156) are formed from the nitride of the semiconductor material, and/or by means of a heating device (135), the solid semiconductor material (153) to be heated is directly heated from above and/or the crucible (130) is directly heated from below, in each case at least partially by thermal radiation (W) produced by means of the heating device. The invention further relates to a device (100) of this type.

Description

Method and device for pulling a single crystal from semiconductor material and semiconductor wafer from silicon

description

The present invention relates to a method for pulling a single crystal from semiconductor material using a device with a crucible, such a device and a semiconductor wafer made from single-crystal silicon.

State of the art

Single crystals made of semiconductor material such as silicon can be pulled out of a

Melt of the semiconductor material are produced. For this purpose, a so-called seedling is usually introduced into the melt and then pulled up. This process is also known as the so-called Czochralski method. The melt itself is obtained by melting generally polycrystalline, ie solid, semiconductor material, which is usually introduced into the crucible as a bed. In general, it is now desirable to keep the oxygen content of such single crystals as low as possible. Contamination in the device or in the components can usually be kept low by using suitable materials. However, semiconductor materials such as the silicon mentioned are usually also coated with an oxide or the semiconductor material oxidizes in air. In the case of silicon, silicon dioxide is created. From JP 2196082 A it is known, for example, to remove such an oxide layer by heating the semiconductor material in the device to a predetermined temperature for a predetermined period of time. Then the device is evacuated or an inert gas atmosphere is formed therein. In addition, it is known, for example from US 2005/0118461 A1, to use a crucible in such devices for pulling a single crystal from silicon

Use silicon nitride, which avoids the risk of contamination by oxygen from the crucible, as is the case with conventional crucibles made of silicon dioxide or quartz. However, when using a crucible made of silicon nitride or corresponding other nitrides, it can sometimes be very high

Temperatures, which are often necessary when pulling single crystals, too

various problems or disadvantages. Against this background, the task arises of using a crucible made of a nitride of a semiconductor material to pull a single crystal out of this semiconductor material to improve the manufacturing process or pulling process.

Disclosure of the invention

According to the invention, a method and an apparatus for pulling a single crystal and a single crystal with the features of the independent

Claims proposed. Advantageous embodiments are the subject of the subclaims and the following description.

The invention relates to a method for pulling a single crystal from semiconductor material using a device with a crucible, which is used to pull the single crystal from a melt in the crucible. A crucible is used as the crucible, which consists at least partially, but preferably also completely, of a nitride of the semiconductor material. In the particularly preferred case of silicon as the semiconductor material, this is silicon nitride (Si3N ₄ ).

The semiconductor material from which the single crystal is to be formed, preferably silicon, is generally introduced into the crucible in solid form, in particular in polycrystalline form. This can in particular also take the form of a bed, ie individual, smaller and / or larger pieces of the semiconductor material are introduced or poured into the crucible. In addition to the crucible, such a device generally also has a suitable pulling device for the single crystal from the melt, which - as will be explained later - is obtained from the semiconductor material. In addition, a heat shield is usually provided, the lower end of which is designed as a type of brim. For a more detailed

Description of the device at this point is based on the following

Versions, especially the description of the figures, referenced. The semiconductor material in the crucible is heated before pulling the single crystal, so that the semiconductor material melts. It is usual or appropriate here

for example a temperature of over 1410 ° C. If single crystals are drawn from silicon, which is found in conventional crucibles made of quartz or silicon dioxide, oxygen dissolves from the crucible material and can be removed from the melt in the form of silicon monoxide (SiO) by lowering the pressure in the device. However, if, for example, silicon nitride is used as the crucible material, the melt dissolves nitrogen until the solution is saturated. There is no chemical compound that is effectively a higher one

Has vapor pressure than silicon and which could be used to remove the nitrogen from the melt by applying a vacuum in the device. In addition, silicon nitride is no longer chemically stable even at normal pressure at the temperatures mentioned and decomposes to silicon and nitrogen. At normal pressure, this decay theoretically begins at around 1380 ° C, in vacuum at around 1200 ° C. This results in the problem of a chemically unstable crucible for the usual pulling process of the single crystal at the aforementioned temperature of approximately 1410 ° C.

According to one aspect of the invention, it is now provided that a partial pressure for nitrogen is set or regulated in the device to a value of at least 0.1 mbar, preferably of at least 1 mbar. In addition, a total pressure of the atmosphere in the device is preferably set or regulated to a value of at least 50 mbar, preferably at least 200 mbar. In general, the pressure can be increased as desired, but if, for example, devices which are actually intended for vacuum are used, an appropriate upper limit may be 800 mbar, since such devices are not suitable for higher pressures. At least one neutral gas, in particular argon, is expediently provided in the atmosphere in addition to nitrogen. Such a neutral gas serves as a protective gas. It is therefore no longer attempted to evacuate the device as much as possible, but instead a specific pressure is set, the partial pressure for nitrogen - ie the presence of nitrogen in the atmosphere - in particular being used to break down the nitride from the semiconductor material. of which the crucible is made to be reduced or even avoided. In conventional crucibles made of silicon dioxide or quartz, the evacuation is used in particular to evaporate oxygen, which is neither necessary nor expedient when using silicon nitride or other nitride for crucibles.

It is particularly preferred if a partial pressure for nitrogen is set or regulated to a value between 1 mbar and 10 mbar, preferably between 2 mbar and 5 mbar. In this way, as close as possible to a triple point between - in the case of silicon as a semiconductor material - silicon nitride, solid

Nitrogen and liquid nitrogen can be approached. For a closer

Explanation should also be made to the description of the figures and the

related diagram or phase diagram.

Another point when using crucibles made from a nitride

Semiconductor material is that when the single crystal is pulled from the melt, crystals form from the nitride of the semiconductor material, for example

Silicon nitride crystals, separate. The molten semiconductor material dissolves the material of the crucible up to the solubility limit, with maximum solubility generally being highly temperature-dependent.

Such crystals from the nitride of the semiconductor material grow not only due to temperature differences, but also due to segregation during crystal pulling. The growing single crystal contains significantly less nitrogen than the melt, which is why the nitrogen is enriched in the melt. In this respect, it is advisable to use this excess Remove nitrogen from the system at a suitable location so that particles from the nitride of the semiconductor material (so-called segregation) do not lead to the dislocation of the single crystal. According to a further aspect of the invention it is therefore provided that at the level of the crucible (reference is made in particular to the direction of gravity

taken) a cooling plate surrounding the crucible, in particular an annular one, is provided, which is in thermal contact with a cooling device surrounding the cooling plate and the crucible. Such a "cooling plate" is a plate or another shaped unit made of a particularly good heat-conducting material. This allows heat or heat to be conducted away particularly well from the surface of the melt or from the crucible. In the

The cooling device can be, for example, water cooling of the system jacket. In this way, the temperature in the region of the crucible can be kept as low as possible, which prevents or reduces the decomposition of the nitride from the semiconductor material. In particular, the surface of the melt can be positioned at the level of the cooling plate, if possible, or vice versa.

It is also particularly expedient if a cooling capacity of the cooling plate is set or regulated by means of a cooling plate heating device. This enables a more precise setting or control of the heat dissipated. A temperature required for this can be measured at a suitable point, for example by means of a temperature sensor, in particular a pyrometric one

Temperature sensor. Without such a cooling plate heating device or in general, a cooling capacity of the cooling plate can also be selected or set once by its thickness (i.e. an expansion in the direction of gravity).

According to a further aspect of the invention, it is provided that crystal needles are formed or grown from the nitride of the semiconductor material (ie in particular from silicon nitride) on a surface of the crucible facing the melt. Such growth of crystals can be achieved, for example, by deliberately changing the partial pressure of the protective gas or neutral gas mentioned and / or by changing the flow of the protective gas or neutral gas mentioned can be varied by the device. In particular, a bead made of the nitride of the semiconductor material forms on the inside of the crucible at about the level of the surface of the melt, on which beads such crystals can then be selectively grown.

In this context, it is particularly preferred if a coating with crystallization nuclei, in particular with triple crystal edges, is provided on the surface of the crucible facing the melt (i.e. on the inside thereof). Such a layer can be produced by chemical vapor deposition (CVD). This is achieved by the fact that CVD process conditions produce particularly strong crystal growth in this crystal direction and so that appropriately oriented nuclei become established. This makes it particularly easy and easy to achieve that the crystal needles then grow in a direction perpendicular to the surface of the crucible, and so a total of a particularly large number of crystal needles can be formed and a particularly large amount of nitrogen can be bound therein.

In addition, it is preferred if one to be pulled over the crucible

Single, surrounding, further, in particular ring-shaped heating device

provided and operated (i.e. actively used for heating). In this way, it can be prevented that the mentioned crystal needles grow too close to the single crystal to be pulled, which leads to undesired dislocations in the

Single crystal. Such a heating device can be specifically set or regulated in such a way that a sufficiently wide area around the single crystal remains free from the crystal needles. An expedient to set

The difference between the temperature, in particular the radiation temperature, the surface of the melt and the (lower) ambient temperature of the melt is preferably between 3 ° C. and 8 ° C. Another point when using crucibles made from a nitride

Semiconductor material, as can also be seen from the foregoing, is that as little as possible unnecessary heat into the system, in particular the crucible, should be introduced in order to avoid degradation of the crucible as far as possible.

According to a further aspect of the invention, it is therefore provided that by means of a heating device the solid and meltable semiconductor material (which is located in the crucible) from above (seen in the direction of gravity) and / or the crucible from below (also seen in the direction of gravity) in each case at least partially heated directly by heat radiation generated by the heater. In this case, direct heating is to be understood to mean that the heat radiation generated by the heating device is unimpeded on the relevant one to be heated

Component meets. In conventional crucibles made of silicon dioxide or quartz, it is customary to indirectly heat the silicon to be melted by means of a heating device which surrounds the crucible laterally or circumferentially, namely by heating the crucible by means of the heating device. Likewise, others are usually

Components such as a susceptor are present, which are also heated and then act as unnecessary or undesirable heat sources.

As a result of the direct heating of the semiconductor material or silicon to be melted in the crucible by means of the thermal radiation, undesired heat or undesired heat sources are largely avoided. For this purpose, the crucible can expediently be moved into a heating position within the device. In this heating position, the heating device is or is in particular arranged in such a way that it surrounds the crucible and is bent inwards (in particular in the radial direction) at an upper end above the crucible with respect to gravity. The crucible for melting the semiconductor material can thus be moved downwards in a targeted manner and the curved material can be used to directly heat the semiconductor material and so on

be melted. The crucible can then be moved up again so that the single crystal can be pulled.

Furthermore, it is particularly preferred in this context if the crucible is arranged on a suspension element which has at least one opening, so that the crucible is generated by means of the heating device by means of the heating device Heat radiation that passes through the at least one opening is directly heated. Such a suspension element can be, for example, a tube with openings or recesses in the tube walls, so that the heat radiation

largely unhindered and thus can directly heat the crucible without unnecessarily heating other components, which would then again serve as undesirable heat sources in the device. It should be noted at this point that this is particularly expedient if the crucible has been moved upwards in order to pull the single crystal. Direct heating of the semiconductor material in the crucible is then generally no longer possible, which means indirect heating

The semiconductor material must be heated via the crucible. Through the

However, use of the proposed suspension means can be largely avoided in this case as well.

In order to carry out the proposed steps, which require setting or regulating values or parameters, in particular a suitable one

Computing unit or control unit can be used.

Each of the aspects mentioned helps to solve the problem mentioned

Using a crucible made of nitride of the semiconductor material by using a

Degradation of the crucible or its material is reduced. Although these different aspects can also be used separately, the

Using several of these aspects, especially all of these aspects, the degradation can be reduced significantly better. The invention further relates to a device for pulling a single crystal from semiconductor material, which has a crucible in which a melt from which the single crystal can be drawn can be kept, the crucible consisting at least partially of a nitride of the semiconductor material. According to a first aspect, the device is set up in such a way that a partial pressure for nitrogen is set or regulated therein during operation to a value of at least 0.1 mbar, preferably of at least 1 mbar. For this purpose, for example, a computing unit or control unit can be provided. According to a further aspect, at the level of the crucible is a cooling plate, in particular an annular one, surrounding the crucible provided, which is in thermal contact with a cooling device surrounding the cooling plate and the crucible. According to a further aspect, the device is set up such that during operation on one of the melts

facing surface of the crucible crystal needles from the nitride of the

Semiconductor material are formed. The mentioned or a further computing unit or control unit can also be provided here. According to a further aspect, a heating device is provided which is arranged in such a way that the solid and meltable semiconductor material from above and / or the crucible from below can each be at least partially heated directly by heat radiation generated by the heating device.

With regard to the further preferred configurations and the advantages of

Device, in particular with regard to the individual aspects, is for

Avoid repetition, refer to the above explanations of the procedure, which apply here accordingly. However, it is also here again

noted that these different aspects can be used separately, but use of several of these aspects, in particular also all aspects, is possible and preferred. The invention further relates to a semiconductor wafer made of single-crystal silicon, which is separated from a single crystal produced according to the invention, for example by means of a wire saw. The semiconductor wafer made of single-crystal silicon preferably has a diameter of at least 300 mm and an oxygen content of less than 1 × ^{10 16} atoms per cm ³ , the oxygen content being understood in accordance with the new ASTM standard. By using a crucible made of a nitride of the semiconductor material, a particularly low proportion of oxygen in the single crystal can be achieved.

Typical for single-crystalline semiconductor material made of silicon

is produced is a nitrogen content of over 1x10 ¹⁵ atoms per cm ³ . Further advantages and refinements of the invention result from the

Description and the accompanying drawing.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the combination indicated in each case, but also in other combinations or on their own without departing from the scope of the present invention.

The invention is shown schematically in the drawing using an exemplary embodiment and is described below with reference to the drawing.

figure description

Figure 1 shows schematically in longitudinal section a device according to the invention in a preferred embodiment, with which a method according to the invention can be carried out.

Figure 2 shows schematically the device of Figure 1 in a different position. FIG. 3 shows a phase diagram for silicon or silicon nitride as a function of temperature and nitrogen partial pressure.

Figure 4 shows schematically part of a crucible of an inventive

Device in a preferred embodiment.

Figure 5 shows schematically a coating of a surface of a crucible of a device according to the invention in a preferred embodiment.

FIG. 1 schematically shows a device 100 according to the invention in a preferred embodiment, which is used to pull a single crystal. With this device 100, a method according to the invention can be carried out, which in a preferred embodiment is to be explained in more detail below with the aid of the device 100. FIG. 2 shows the device 100 from FIG. 1 in a different position while a method according to the invention is being carried out. In the following, Figures 1 and 2 will be described in a comprehensive manner.

A crucible 130 is arranged in the device 100, into which solid semiconductor material can be introduced. In the example shown in FIG. 1, semiconductor material is indicated by reference numeral 153 and is, for example, silicon, here in the form of a bed, ie in the form of many individual pieces, here polycrystalline pieces. The crucible 130 in this case consists at least partially, but in particular completely, of a nitride of the flalbonductor material, that is to say, for example, silicon nitride (Si ₃ N ₄ ).

This solid semiconductor material is melted, so that a melt or melted semiconductor material 154 results in the crucible 130, as shown in FIG. 2. For this purpose, a heating device 135 is provided which surrounds the crucible 130. This heating device 135 can be, for example, an oven or the like. A heat shield 136 is attached above the semiconductor material 153 or the melt 154 and the crucible 130, which heat shield can serve to retain the heat that is later emitted by the melt 154, so as to reduce the energy consumption.

A single crystal 150, as can be partially seen or indicated in FIG. 1, can then later be formed from the melt using a pulling device 140. A more detailed description of the pulling of the crystal is not intended to be given within the scope of the present invention, since this basically does not differ from known methods. In the position of the crucible 130 shown in FIG. 1, a heating position PH, heat radiation generated by the heating device 135, here indicated by an arrow W, can directly heat the solid semiconductor material 153. For this purpose, the heating device 135 is bent radially inwards at an upper end or region, so that the heat radiation W can reach the solid semiconductor material 153 more directly and over a large area. In this way, indirect heating of the solid

Semiconductor material 153 can be reduced via the crucible 130 or its wall, which would lead to undesirable heat sources within the device and thus would contribute to the degradation of the crucible 130. It goes without saying that the crucible 130 must be able to be moved into the heating position PH in a suitable manner.

After the solid semiconductor material 153 has been melted and the melt 154 has been formed, the crucible can be moved into a pulling position PZ, in which the single crystal 150 can be pulled out of the melt 154, as shown in FIG. 2.

The crucible 130 is arranged on a support means 161, for example in the form of a tube or the like, which in turn is arranged in or on a collecting trough 160. Openings are now provided in the suspension means 161, designated 162 here by way of example. These openings 162 preferably extend at least 50% of the circumference (with respect to an axis in the direction of gravity) of the suspension element 161. In this way it can be achieved that heat radiation W, which is generated by means of the heating device 135, in particular in the pulling position PZ, directly can reach the crucible 130 or its wall, in particular also at locations or areas that would be covered using conventional suspension means. In this way, undesirable heat sources within the device can be avoided or reduced, which would otherwise contribute to the degradation of the crucible 130.

Furthermore, a cooling device 120 is provided in the device 100, which surrounds the crucible 130 and which can be, for example, water cooling. Furthermore, an annular cooling plate 121 is provided, which likewise surrounds the crucible 130 (at least in the position shown in FIG. 2) and which is in thermal contact with the cooling device 120. The cooling plate in particular has a thermally highly conductive material, for example plates made of isostatically pressed graphite. Above the cooling plate 121 are a number of plates 122 made of thermally insulating material, for example

Carbon felt or carbon hard felt provided. In this way, heat that is generated or present in the crucible 130 or the melt 154 can be dissipated particularly effectively and quickly, as is indicated by an arrow F, which represents a heat flow. By using the plates 122, the heat flow can be directed to the outside

In addition, a cooling plate heating device 125 is provided, by means of which the cooling capacity of the cooling plate 121 can be adjusted or regulated. In particular, a maximum output, to which the cooling plate is designed in connection with the cooling device 120, can be specifically reduced, if necessary.

Furthermore, the device 100 contains a further, in particular annular,

Heating device 138 is provided, which faces a surface of the melt 154 and surrounds the single crystal 150 to be pulled. By means of this further

Heating device 138 can ensure that crystal needles, which are formed in the melt and on the surface of the crucible facing the melt, do not grow too far to the single crystal 150. For this purpose, also on the

Reference made to Figures 4 and 5.

FIG. 3 shows a phase diagram for silicon or silicon nitride, a pressure p in mbar and a logarithmic representation for a partial pressure of nitrogen over a temperature T in ° C. being plotted. Three phases are shown, with P1 showing a phase of solid silicon nitride (ShNU), P2 showing a phase of solid silicon and P3 showing a phase of liquid silicon. This phase diagram shows the dependencies of the conversion from silicon to silicon nitride on both the temperature T and the partial pressure of

Nitrogen P recognizable. This phase diagram shows that at a temperature higher than the melting temperature of silicon (here around 1420 ° C), a certain

Partial pressure for nitrogen is appropriate to remain in a range (as close as possible to the triple point) in which all phases involved are stable, or the

Conversion technically irrelevant is slow. In particular, the conversions from silicon nitride to silicon and nitrogen, and the conversion from liquid silicon to silicon nitride are undesirable. The conversion of liquid silicon into crystalline, i.e. solid silicon, is the desired process. In particular, a range between 1 mbar and 10 mbar, particularly preferably between 2 mbar and 5 mbar, is particularly suitable for this. this applies

in particular when the temperature of the melt is kept as close as possible above the solidification temperature of silicon, for example by the other measures presented in the context of the invention.

The nitrogen required for this can, for example, be introduced into the device 100 via the openings 101 shown in FIGS. 1 and 2 and set or regulated by means of a computing unit 110 designed as a control or regulating unit. In addition, the atmosphere in the device can contain a neutral gas such as argon, as has already been explained in more detail at the beginning.

FIG. 4 schematically shows part of a crucible 130 of a device according to the invention in a preferred embodiment, as is shown for example in FIGS. 1 and 2.

It can be seen here that a bulge 155 forms on a surface 131 of the crucible 130 facing the melt on fleas of the surface 151 of the melt. The background to this is that the removal of silicon from the melt to form the single crystal increases the proportion of nitrogen in the melt. This creates an imbalance, which is reflected in the formation of crystalline silicon nitride. Crystals made of silicon nitride that float freely in the melt and float freely on the melt surface are undesirable since these can lead to dislocation of the single crystal. For this reason, crystal needles made of silicon nitride are specifically formed on the surface 131 on this bead 155. This takes place in that the crucible wall is cooled at this point by the cooling plate on the outside and thereby also the inside and locally the melt of semiconductor material lying thereon is cooled. This cooling only enables the crystallization of silicon nitride. By keeping the temperature higher than the solidification temperature of silicon, only the silicon nitride can crystallize on existing germs at this point. In addition, these crystal needles form a meshwork in which floating crystals, which may arise sporadically, get caught and thus become harmless.

The cooling position always remains at the level of the melt, since the crucible has to be moved continuously upwards during crystal pulling. Therefore, crystal needles are created over the entire height of the inner wall of the crucible, which is smeared by the melting surface. Such crystal needles are designated 156 by way of example.

Overall, it can thus be achieved that the region of the melt in which the single crystal is formed or drawn is as free as possible from such floating crystals, so that dislocations in the single crystal occur as far as possible.

5 shows a coating 170 of a surface of a crucible

Device according to the invention in a preferred embodiment, as it

is shown, for example, in FIG. This coating 170 is, in particular, a CVD layer with crystallization nuclei 171, which particularly preferably have triple crystal corners, as designated by way of example at 172. This way can be achieved be that the crystal needles to be formed on the surface of the crucible grow inwards as perpendicularly as possible to the crucible wall on the melting surface.

By using the further, in particular annular heating device, which is explained with reference to FIGS. 1 and 2 and surrounds the single crystal, it can also be achieved that these crystal needles are not too close to the single crystal

grow so that any dislocations in the single crystal are avoided.

Overall, the proposed method and the proposed device can be used to form a particularly low-oxygen single crystal, preferably a single crystal made of silicon, because despite the use of, for example

Silicon nitride as a material for the crucible the problems that arise or

Disadvantages, as mentioned at the beginning, can be largely reduced or avoided.

Claims

claims

1. A method for pulling a single crystal (150) from semiconductor material using a device (100) with a crucible, which is used to pull the single crystal (150) from a melt (154) in the crucible (130),

wherein a crucible is used as the crucible (130), which consists at least partially of a nitride of the semiconductor material,

characterized in that in the device (100) a partial pressure (p) for nitrogen is set or regulated to a value of at least 0.1 mbar, and / or

that at the level of the crucible (130) a cooling plate (121) surrounding the crucible is provided, which is in thermal contact with a cooling device (120) surrounding the cooling plate (121) and the crucible (130), and / or

that on a surface (131) of the crucible facing the melt

Crystal needles (156) are formed from the nitride of the semiconductor material, and / or that the solid and to be melted by means of a heating device (135)

Semiconductor material (153) from above and / or the crucible (130) from below are each at least partially heated directly by heat radiation (W) generated by the heating device.

2. The method according to claim 1, wherein in the device (100) the partial pressure (p) for nitrogen is set to a value between 1 mbar and 10 mbar, preferably between 2 mbar and 5 mbar.

3. The method according to claim 1 or 2, wherein in the device (100) of

Partial pressure (p) for nitrogen is set or regulated to a value of at least 1 mbar, and wherein in the device (100) a total pressure of

Atmosphere is set or regulated to a value of at least 50 mbar, preferably at least 200 mbar.

4. The method according to claim 3, wherein at least one neutral gas, in particular argon, is provided in the atmosphere in addition to nitrogen.

5. The method according to any one of the preceding claims, wherein at the level of the crucible (130) the cooling plate (121) surrounding the crucible is provided, which in thermal contact with a cooling device (120) and the crucible (130) surrounding cooling device (120) stands, and wherein a cooling capacity of the cooling plate is adjusted or regulated by means of a cooling plate heating device (125).

6. The method according to any one of the preceding claims, wherein on the

Melt-facing surface (131) of the crucible crystal needles are formed from the nitride of the semiconductor material by providing a coating with crystallization nuclei (171), in particular with triple crystal edges (172), on the melt-facing surface (131) of the crucible.

7. The method according to any one of the preceding claims, wherein on the

Melt-facing surface (131) of the crucible, crystal needles (156) are formed from the nitride of the semiconductor material, and a further, in particular annular, heating device (138), which surrounds the single crystal (150) to be drawn, is provided and operated above the crucible (130) becomes.

8. The method according to any one of the preceding claims, wherein by means of

Heating device (135) the solid and to be melted semiconductor material (153) is heated directly from above by heat radiation (W) generated by the heating device by positioning the crucible (130) within the device (100) in a heating position (PH).

9. The method according to claim 8, wherein the heating device (135) is arranged such that it surrounds the crucible (130) and is bent inwards in the heating position (PH) at an upper end above the crucible.

10. The method according to any one of the preceding claims, wherein by means of

Heating device (135) the crucible is heated directly from below by heat radiation (W) generated by the heating device, by arranging the crucible on a support means (161) which has at least one opening (162), so that the crucible by means of the heating device of the heating device generated heat radiation (W), which passes through the at least one opening (162), is directly heated.

11. Device (100) for pulling a single crystal (150) from semiconductor material, with a crucible (130) in which a melt (154) can be kept, from which the single crystal (150) can be pulled,

wherein the crucible (130) is at least partially made of a nitride of the

Semiconductor material,

characterized in that the device (100) is set up in such a way that a partial pressure (p) for nitrogen is set or regulated to a value of at least 0.1 mbar during operation, and / or

that the device (100) is set up in such a way that crystal needles (156) are formed from the nitride of the semiconductor material during operation on a surface (131) of the crucible facing the crucible, and / or

that a heating device (135) is provided which is arranged in such a way that the solid and meltable semiconductor material (153) from above and / or the crucible (130) from below can each be at least partially heated directly by heat radiation (W) generated by the heating device are.

12. The device (100) according to claim 11, wherein at the level of the crucible (130) the surrounding, particularly annular, cooling plate (121) is provided, which is in thermal contact with the cooling plate (121) and the crucible (130) surrounding cooling device (120), and wherein a cooling plate heating device (125) is provided for setting or regulating a cooling capacity of the cooling plate (121).

13. The device (100) according to claim 11 or 12, wherein the device (100) is set up in such a way that crystal needles (156) are formed from the nitride of the semiconductor material on the melt-facing surface (131) of the crucible, and wherein on the the melt facing surface (131) of the crucible a coating with crystallization nuclei (171), in particular with triple

Crystal edges (172) is provided.

14. The device (100) according to one of claims 11 to 13, wherein the device (100) is set up in such a way that crystal needles (156) are formed from the nitride of the semiconductor material on the melt-facing surface (131) of the crucible, and wherein A further, in particular annular, heating device (138) surrounding the single crystal (150) to be pulled is provided above the crucible (130).

15. The device (100) according to any one of claims 11 to 14, wherein the

Heating device (135) is provided, which is arranged such that the solid and meltable semiconductor material (153) can be heated directly from above by heat radiation (W) generated by the heating device, and the crucible for this purpose within the device in a heating position (PH ) can be positioned.

16. The apparatus (100) according to claim 15, wherein the heating device (135) is arranged such that it surrounds the crucible (130) and is bent inwards in the heating position (PH) at an upper end above the crucible.

17. The device (100) according to any one of claims 13 to 19, wherein the

The heating device (135) is arranged in such a way that the crucible can be heated directly from below by heat radiation (W) generated by the heating device, and the crucible is arranged on a support means (161) which has at least one opening (162), so that by means of the heater of the crucible by means of it

Heater generated heat radiation (W) by the at least one

Opening (162) occurs, is directly heated.

18. Semiconductor wafer made of single-crystal silicon, which has an oxygen content of less than 1x10 ¹⁶ atoms per cm ³ and a nitrogen content of more than 1x10 ¹⁵ atoms per cm ³ .