DE4103086A1 - Deposition of high purity silicon by thermal decomposition - using several microwave heating sources for even heating of substrates and reduced contamination levels - Google Patents

Abstract

High purity semiconductor material, especially Si, is deposited by thermal decomposition of gaseous cpds. on substrates heated by the absorption of electromagnetic energy. The process is carried out in a reactor with a metallic base-plate containing spray-heads for gas supply and removal and carrying a bell-jar which fits over the base-plate and is hermetically sealed to it. Pref. at least one generator is used externally to generate electromagnetic waves (em-waves) which are radiated into the dome at several places, and the inner lining of the reactor dome is made of a material which reflects the em-waves virtually loss-free. The energy is radiated into the dome via at least one membrane, pref. 4-8 membranes, which is (are) fully transparent for the wavelength used and on which no depsn. occurs of the semiconductor material. The membrane is pref. quartz which is pref. cooled. The energy generated, which is pref. microwave energy in the range 0.5-3.0 GHz, is pref. transferred via wave-guides, whereby relecting mirrors may be used to radiate energy to several reactors. The substrates are pref. heated until they reach the temp. at which they start to reflect the microwave energy, pref. a temp. of up to 650 deg. C. USE/ADVANTAGE - The process achieves homogeneous heating of the substrates resulting in less mechanical damage in the substrates and so less breakage during subsequent processing. The heating method also results in lower contamination levels than current methods, e.g., the Siemens process. This is further decreased by carrying out the deposition at lower temps. using silane as the Si source, resulting in a carrier lifetime of better than 5 msecs. and a resistivity (n-type) of 2000 ohm.cm. with all contamination levels below the sensitivity level of the NIAA method. The process gives much accelerated heating, reducing the process-times significantly

Description

The invention relates to a device and a Ver drive to the deposition of pure semiconductor material, esp special silicon, by thermal decomposition gaseous Compounds of this semiconductor material on heated Support bodies in a separation reactor.

Such manufacturing process of semiconductor material, at which is a volatile semiconductor compound, for example a silicon compound, thermally to form free Silicon decomposes and the resulting sili from the gas phase cium is deposited on a heated support body known for a long time. Such a device is used for example in the German patent 28 54 707 be wrote. The reactor vessel consists of a base plate with brackets for the support body, supply and discharge openings for the gaseous reactants and one gas-tight on the Base plate-mounted bell, for example, from the reak silver-plated or silver-plated stainless steel with coolable coat.

The supporting bodies are, for example, U-shaped silicon thin rods that are mounted on the brackets of the base plate and connect two brackets to each other  the. These brackets have contacts through which the Thin rods can be conductively connected to the power grid. The deposition of silicon from trichlorosilane according to the so Siemens process mentioned takes place on these thin rods a temperature of at least 900 ° C, usually 1000- 1200 ° C caused by the current flow due to the contact voltage applied is maintained. Other Ab divorce processes take place at a lower temperature, for example the deposition of silicon from silane a temperature of only about 400 ° C.

After silicon only at a temperature from about 400 ° C in sufficient electrical conductivity (the specifi resistance then reaches a value of about 0.5 Ωcm), must be used to heat the deposition Silicon body otherwise at this temperature respectively. For this is located in the apex of the deposition a lock through which a heating finger enters the Reaction space can be introduced. Under inert gas, especially nitrogen, the reaction chamber is up to Ignition temperature warmed up, from which to further heating by the current flow in the thin rods.

These devices known from the prior art and Procedures have serious disadvantages. The opening of the Reactor space for the introduction of the heating finger leads to the fact that Foreign particles are increasingly introduced into the reactor space the. So are for uniform heating of the reaction space high temperatures in the heating finger necessary that a ver vaporization of metal from the finger into the reaction space. This leads to further undesirable contamination of the Semiconductor material with metal atoms. Because the heating must be carried out under inert gas, for example nitrogen, are residual concentration in the actual deposition process  tion of nitrogen before, which increases nitrogen concentration in the deposited poly-silicon leads. Installation of nitrogen causes stacking errors in the following Manufacture of single crystal material. Furthermore he the heating of the thin rods requires 30-60 minutes, too additional period of time in which the system is at a standstill and the reduces the economy.

Further contamination risks arise during the separation of silicon from trichlorosilane through the electrical and thermally induced diffusion of atoms from the electrodes into the semiconductor rods if the during the deposition Rods electrically by current flow between the electrodes be heated. This risk of contamination can only be avoided be avoided if the deposition, for example of Silicon from silane, at a lower temperature alone by heating with electromagnetic radiation, for example wise microwave, done.

One has started to open the reactor and the Avoid introducing the heating finger in that the The thin rods are heated by microwaves. In DE 37 39 895 is used, for example, to heat the rods the upper opening of the separation reactor is a microwave heater attached. A fan is used for better Ren distribution of the irradiated microwave on the Inside the reactor, but part of the microwave from the Base plate is reflected and thus in the waveguide got back. The necessary to irradiate the microwave Shaft guide tube therefore has a tuning device to the reflection from microwave back into the generator itself to avoid.

The method described has the disadvantage that Irradiation of the microwave from the top of the reactor  the thin rods are heated unevenly. This leads to a delayed start of the current flow, because parts of the rod heat up more slowly. this leads to in addition to thermal tensions and hairline cracks in the bars ben and can break the bars, but at least mechanical Cause instability after cooling and Expansion breaks or malfunctions in the following procedures, e.g. B. with crucible-free zone pulling or sawing. This effect is even used in processes such as an example as described in DE 34 28 255, to facilitate the Shredding of the material by the at the local Overheating caused cracks and tension turns. Also the attachment of the fan and the tuning device for better distribution of the microwave and Avoidance of reflection is not enough to avoid radiation even heating of the rods from above, esp especially in the lower part.

The procedure is particularly unfavorable if the Ab divorce by microwave heating alone, and not by Current flow should take place, as is the case with the deposition of Silicon from silane due to the lower deposition temperature rature is the case, but it is the only method of ab separation of rod-shaped support bodies through contamination Avoids electro diffusion. Heating the rods from above leads to an unequal one moderate deposition of silicon at the top of the rod and so with too uneven rod thickness, with which the rods for certain applications, such as zoning, are completely unintended are suitable.

The invention was therefore based on the object, a Vorrich device and a method for the deposition of semiconductor mate rial, for example silicon, by thermal decomposition to find gaseous precursors that have a uniform,  contamination-free heating of the semiconductor material under Avoiding the above disadvantages allowed.

This problem is solved by a device for Ab separate from pure semiconductor material, especially sili cium, by thermal decomposition of gaseous compounds of this semiconductor material on heated support bodies, absorb the electromagnetic radiation when heated ren, in a separation reactor consisting of a metallic base plate with nozzles for supplying and removing gases and one put over it, on the edge with the base plate gas-tight, coolable bell, marked by at least one arranged outside the reactor Generator for generating electromagnetic waves, wherein these are irradiated at several points in the reactor the, and a reactor inner wall made of a material that electromagnetic waves reflected almost lossless. The task is still solved by a procedure under Use of this device, characterized in that is that the heating of the material of the support body through electromagnetic radiation from multiple sources homogeneous he follows.

For the application of the invention, all reactors, in particular special also fluidized bed reactors or reactors from separation of thin layers, such as epitaxial reactors, suitable for the separation of substances from gaseous Pre-products on finely divided granules (e.g. in Fluidized bed reactors) or preformed supports, such as for example rods, balls or plates that serve on be heated.

The purpose of the invention is to have a homogeneous radiation distribution to obtain lung in a reaction zone of the reactor. From  The execution differ depending on the reactor type form this reaction zone.

For example, one embodiment of the invention is based on separation reactors as they are in the prior art are written. In this embodiment the reactor is according to the invention a homogeneous distribution of the radiation in entire reactor interior reached. The preferred cylinder The reactor consists of a metallic base plate and a cylindrical housing. The base plate is min at least two brackets for one U-shaped rod each of the semiconductor material. She also owns an inlet and outlet opening for the gaseous reaction components. In special embodiments, the stops for the semiconductor material with contacts for application tension through the U-shaped rod.

The reactor housing, which connects gastight to the base plate which, for example, can be screwed, is preferred double-walled for the flow of coolant, in particular Water, running. In contrast to the prior art however the opening for the introduction of the heating finger or of the shaft guide tube in the top of the reactor.

The description of this reactor must be given as an example are summarized and does not constitute a restriction of the invention thank you.

A reactor bell is connected to at least one generator generation of electromagnetic waves. There one heating the semiconductor material as uniformly as possible should be sufficient to crack and break through thermal expansion Avoid using multiple generators according to the object of the invention in the reactor brings that a homogeneous field distribution of the irradiated  electromagnetic radiation right inside the reactor results. Due to the Bedin prevailing inside the reactor The generator or generators is more convenient wise outside the case. The generator is then in the Usually by one used for the electromagnetic Radiation permeable and non-absorbing Membrane, for example made of quartz, from the inside of the reactor Cut. The membrane is preferably made of double walls leads, so that a non-polar coolant, for example Paraffin oil, which is the irradiated electromagnetic Radiation not absorbed, can be passed through.

Guiding the electromagnetic waves from the generator to Membrane can expediently be used with commercially available waveguides. It has especially in particular the attachment of one generator with several outgoing waveguides proved to be favorable, the the radiation into the interior of the reactor via membrane windows ren, so that the most homogeneous distribution of radiation inside the reactor and thus a uniform heating of the Semiconductor material takes place.

The arrangement of the openings with the membranes for irradiation the electromagnetic radiation is from the reactor as well on the shape, mass and number of supports pending. Favorable arrangements are easy for the person skilled in the art evident. The required homogeneous distribution of the beam lung is particularly in two or more, especially in 4-8 entry openings for electromagnetic radiation reached. For the deposition of silicon from trichlor silane preferably used U-shaped support body is ins special radiation on each of the three sides of the U- shaped body favorable from the reactor cylinder, the expediently two longer, parallel parts of the rods  two membrane openings are irradiated so that results in a total of 5 irradiation openings.

A continuation of the inventive concept consists in for several reactors, a generator with the corresponding Provide waveguides so that the generator for each the heating time to the respective reactor by actuation a tilting mirror in the waveguide can.

Another embodiment is the application of the inven dung on a fluidized bed reactor. According to the invention is a homogeneous distribution of the Radiation in particular in a defined reaction zone reached within the reactor. As described in the above NEN embodiment of the deposition reactor remains Basic principle of the reactor, consisting of a base plate with a coolable bell placed over it, preserved. About it In addition, an advantageous in the upper region of the bell Outlet opening provided for process gas. The support body from Semiconductor material exist in this embodiment prefers from granulate, which before the start of the Reak tors in a thin, about 50-350 mm, especially 75-250 mm thick layer on a perforated plate in the lower area of the cylindrical reactor supports. The perforated plate has Openings whose diameter is usually smaller than that The diameter of the granulate is. In particular, Granu lat with a diameter of 150-600 µm has proven to be favorable. In operation, the process gas flows through these openings partly from a volatile, thermally decomposable Ver binding of the semiconductor material, for example silane, be stands. The grain size of the semiconductor material is so designed that the semiconductor particles by the pressure of the  gas flowing out of the perforated plate is kept in motion will. In particular, a small percentage of the part chen completely lifted off the floor slab and in one ent distance of 1001-500 mm from the base plate Reaction zone are promoted. The pressure of the process gas which is necessary to get particles of a certain mass into the Re Transporting an action zone is therefore easy for the specialist to determine.

According to the invention by several, preferably 4-8 Membra electromagnetic radiation into the interior of the reactor irradiated that the most homogeneous radiation possible Reaction zone takes place. This is preferably the heating tion of the lighter, through the gas flow into the reaction zone transported carrier and a deposition of semiconductors preferred material in the reaction zone, but not in the colder and non-irradiated zone above the perforated plate, so that a caking of the heavier one was lying on the bottom plate ing semiconductor material is avoided. The heavier ones Carrier bodies sink to the ground after deposition, with what ultimately a function of the pressure of the reaction gas uniform grain sizes of the product results.

The homogeneous distribution of electromagnetic radiation especially in the reaction zone partial to a uniform deposition of semiconductors material and thus to a particularly great regularity and homogeneity of the product granules. Because according to the invention the proportion of radiation absorbed by the reactor wall is heated and kept as low as possible, he follows in particular an absorption of the radiation by the Support body. This is a particularly lossless heat tion of the support body and a high energy yield enough.  

The generators used generate electromagnetic ones Radiation of a frequency emitted by the material from which the tra body exist, is absorbed as completely as possible, so that the same is heated. At the same time Expediently uses radiation that is as little as possible is absorbed by the reactor wall. The frequency of the Radiation, which is used in the best case, depends also on the thickness of the support body used.

Microwaves with a frequency of 0.5-30 GHz are used in the Rule not absorbed by metals, but reflected. It however, almost complete absorption of electromagnetic radiation of this frequency by un doped semiconductor materials, for example silicon. At Increasing the temperature usually increases the conductivity speed of such semiconductors, but this leads to a reduction in Absorption of electromagnetic radiation leads. Molecules with a permanent dipole moment also absorb microwel len.

The interior has proven to be particularly beneficial of the reactor used, for example made of stainless steel consists of silvering or plating with silver. This results in a particularly extensive reflection of the radiated electromagnetic radiation and a stei reduction in the homogeneity of the radiation inside the reactor what for a particularly even and gentle heating of the semiconductor material and to shorten the heating time leads. However, versions are also possible in which NEN the reactor wall is covered with quartz. The inner wall is ge from the outside through the double-walled reactor housing cools. Back reflection only occurs when the carrying body have reached sufficient conductivity and thus with electricity no longer absorb the river. Before that, almost completely  absorption of radiation by the support body and with almost lossless heating.

In the embodiment of the reactor, in the mounts (Electrodes) are provided for the support body this is preferred if only by irradiation of the electromagnetic radiation does not affect the deposition temperature is achieved, from an electrically highly conductive material, to avoid heating when current flows through for example made of graphite. It is useful to have a poss provided for cooling the electrodes.

The support body on which the material to be deposited is deposited is stored, can have different forms, which ins particular depend on the type of reactor. So at Fluidized bed reactors a granulate from small round or polygonal particles of a diameter larger than that The diameter of the perforated plate is used for deposition gene, in the case of epitaxial reactors in particular disc-shaped bodies by. As a rule, however, it will be thin rods.

The shape and mounting of the support body is also of dependent on the deposition temperature. Especially in the out leadership form in which thin rods serve as a supporting body the temperature at which the decomposition reaction of the volatile component and thus the deposition of material the thin rods begins, decisive for whether in the parting voltage reactor to the electrodes of the holders must be applied or whether the heating of the thin rods on the deposition temperature only by electromagnetic table radiation occurs. For example, the hosts Economic deposition of silicon from trichlorosilane Temperatures of around 900-1250 ° C are necessary. The support body be are then conveniently made of thin, 5-15 mm thick U-shaped  Silicon rods that are mounted on the brackets that a voltage can be applied. At the Ab separation of silicon from silane, which is already at 300-400 ° C begins, the heating of the thin rods can be done by elec tromagnetic waves occur. Therefore are free in the room standing moldings, in particular rods or plates, as Suitable body. The bars can be square, however also have and from polygonal or oval cross sections monocrystalline or polycrystalline semiconductor material be. Round souls, which after Ab divorce without further processing, for example directly to the Zone drawing process can be supplied. The supporting body but can also consist of all other materials that Absorb electromagnetic waves and heat up in the process men.

Also in the embodiment of the fluidized bed reactor only heating of the support body by electromagnetic table radiation possible. This is the type of reactor for the thermal deposition from compounds that are already decompose at a lower temperature, especially for an ab separation of silicon from silane, suitable.

The frequency of the generators for electromagnetic radiation development for heating silicon, which is preferred in the area the microwave is usually also of the strength depending on the material. Thick rods are preferred with smaller frequencies heated up. For example, in Case of silicon frequencies in the range of 0.5-3.0 GHz used when rods with a diameter of 5-15 mm are used come as a support body. Especially cheap Microwave from 2.0-2.8 GHz, especially 2.45 GHz proved sen, because at this frequency the surface is even is warmed and thus a particularly uniform separation he follows.  

The performance of the generators depends on the reactor size Mass of the rods and those to achieve conductivity or the temperature required for the deposition. For example To deposit silicon from trichlorosilane, a tem temperature range in which the electrical Resistance of silicon is low enough to pass through Current flow the actual separation temperature for sili cium from trichlorosilane at 900-1250 ° C. This is the case from about 400 ° C. When depositing from silane a temperature of 300-400 ° C is sufficient. Because the reactor wall, especially a silver-plated, the irradiated elek tromagnetic wave completely reflected, are already Power from 1 kW is sufficient, good results will be achieved with powers from 2 to 10 kW. It can be a genera can be used, the total power up to provides electrical ignition, or several accordingly ge lower performance.

In contrast, for example Silicon from silane generators correspondingly lower Power range, for example 1-10 kW corresponding to that Reaction volume, in continuous operation during the deposition used. Since the deposition temperature is lower, in this case, the current flow can be dispensed with, whereby temperature and voltage dependent impurities due to solid diffusion can be avoided.

The power regulation of the generators depending on the Temperature of the support body can be measured by appropriate measuring elements, for example sensors, or for example by Resistance measurement of the current flow through the silicon rod respectively. If the further heating, for example at the Silicon must be heated by current flow Transition from microwave heating to electrical heating  not switched by complex measurement or control will. Once the conductivity of the silicon is due a higher temperature, for example at a resistivity less than 1 Ωcm, preferably has exceeded even below 0.1 Ωcm, the microwave will no longer absorbed by silicon, but reflected and switches the heating of the reactor by the generator automatically. This is the case from about 500 ° C, especially The pure silicon support bodies also become temperatures reached up to about 650 ° C. The heating time is determined by the one radiated power is specified and is accordingly 2-10 Minutes.

The radiation of the electromagnetic waves in the case deposition from trichlorosilane already under hydrogen Atmosphere. This eliminates the costly rinse development of the reactor with inert gas, for example nitrogen or argon, as they are due to the conventional process opening the system was necessary. Against it is a punishment not possible in a polar atmosphere, for example with Presence of trichlorosilane in the reactor room, since then the Radiation is absorbed by the gas, causing heating of the gas in the reactor room. Only with simultaneous Er heating by electromagnetic waves and deposition the inside of the reactor has already been charged with the gas mixture from which the deposition takes place, for example silane or silane / hydrogen mixtures.

The invention has compared to the methods in the prior art nik, a heating finger ver to heat the body turn, the advantage that heating the interior of the reactor can be completely contamination-free. Because a very selek tive heating of the supporting body takes place, the evaporation  has been shown to be polycrystalline Lines silicon in the metal contents, measured with INAA (instrumental neutron activation analysis) is discontinued.

The reduced heating-up time of 2-10 compared to 30-60 minutes not only has the advantage of speeding up the process rens. In the previous procedures had during this time are flushed with inert gas, while in the invention Process due to the closed reactor heating can already take place under hydrogen or the process gas. This also saves inert gas, which continues has the advantage that the quality of the crystals improves is because storage of nitrogen in abge different polycrystalline silicon leads to stacking errors.

Compared to the methods shown in the prior art, the electromagnetic radiation for heating up the carrier use pern, has the inventive method and The device according to the invention has the advantage that a particular uniform and loss-free heating of the support body follows. Through the use of silver and silver clad stainless steel inside the reactor is done especially lossless reflection of the radiation and thus sole Er heating of the semiconductor material and a shortening of the on heating time. Application of the invention to a vertebra Layer reactor has the particular advantage that complete reflection of the radiation through the reactor wall and the exclusive irradiation of the reaction zone energy only used to heat the supporting body and thus serves to separate material. The The radiation and energy yield is particularly high. In addition, contamination of semiconductor material completely avoided because of thermal or electrical diffusion  does not occur in this type of reactor. The use of this Reactor for the deposition of silicon from silane was only by using lossless heating electromagnetic radiation economical.

Because the radiation into the reactor at several points he follows that depends on the shape of the reactor and the support body there is no local imbalance in the warming of the support body. This can also help Radiation distribution means such as fans that also represent wear parts, with advantage those who dispense the. Back reflection of microwave power in the generato Ren takes place only at the end of the heating up period, if due to the reached the electrical conductivity of the support body absorb more, therefore also need means that ver avoid back reflection in the generator be provided.

The mentioned thermal stresses and hairline cracks in the bars, those for breaking the bars, or at least for mechanical in stability and after cooling and removing Breaks or disruptions in subsequent procedures, e.g. B. with crucible-free zone pulling or sawing, are avoided. The yield in the deposition process itself and in the following procedures becomes essential improved. Especially when the deposition alone by microwave heating, and not by current flow is said to be like this in the deposition of silicon from silane due to the lower deposition temperature, are uniformly thick and therefore for processes like that Zone pulling receive particularly suitable loss-free rods. The process therefore has great economic advantages partly compared to the known prior art.

In the following the device according to the invention and the Method explained in more detail using exemplary embodiments. The examples are intended solely for better understanding and do not limit the inventive concept represents.

example 1

In a test deposition system with a total height of 80 cm and the inner quartz bell became three silicon rods (souls) in a U-shape with a diameter of 8 mm and a Ge built-in length of 110 cm, the conical ends of the rod with graphite brackets to the voltage generator were closed.

When the microwave unit is switched on, consisting of 4 generators with 1 kW each, which have waveguides made of silver-plated brass and a length of one meter each via quartz windows that can be cooled with paraffin oil, each around 90 ° around the cylinder circumference of the reactor and along the cylinder axis the height by 20% of the total reactor height were placed on the reactor, a complete absorption of the radiated energy was registered since the power reflected in the waveguide was zero. After only 5 minutes, the resistance of the silicon rod (which was measured in the experiment with thermocouples), which had risen to about 400 ° C., reached such a low resistance that measurement was carried out at an applied voltage of 250 V current flow. As a result, the temperature and thus the conductivity increased so rapidly that a current of 40 A already flowed after a few seconds (5 sec) and after a short time the separation temperature of <1000 ° C was reached. With a mixture of 4 kg of trichlorosilane in 2 Nm ³ / h of hydrogen, a separation rate of approximately 1.2 mm / h was achieved. With increasing deposition of polycrystalline silicon and thus the diameter, the current flow rose to 180 A / A 100 V until the final diameter of 30 mm was reached.

The polycrystalline deposited in this way Silicon was zoned into a single crystal Recrystallized rod and was in the metal contents, measured with INAA, significantly reduced. There were con constant values of 120 pptw Fe and 15 pptw Cr compared to 300 pptw Fe and 35 pptw Cr, which in the previous state of Tech were not common.

Example 2

In a reactor according to Example 1, but with silver clad walls, became a soul of equal proportions built. Heat after starting the microwave heating system the U-shaped silicon rods due to the smaller Radiation absorption of the reactor wall even faster, which reduces the heating-up time to 3.5 minutes could. The maximum temperature in the rod by the Microwave heating was achieved because of the lower Radiation increased a little, so that even with a chip voltage of 120 V there was a continuity. This too Test separation went smoothly. The deposition rate was approx. 1 mm / h. The polycrystalline silicon rod was as in Example 1 further processed after the zone drawing process and gave no deteriorated values compared to Example 1 for the lifetime of the minority charge carriers (<1000 µsec). The metal values were also very good, representing Fe measured with the INAA method, namely under the night limit of 50 pptw.  

Example 3

A reactor was constructed in a similar manner as in the Examples 1 and 2. However, for further limitation the heat radiation is a quartz bell shaped reak outside with a chilled silver foil. The silicon rods were mounted on graphite brackets, but not connected to a voltage source.

After switching on the microwave unit, 5 min. waited under low hydrogen flow until the silicon the temperature had reached about 550 ° C. Then was changed from hydrogen to a mixture of hydrogen + Silane switched. This mixture had a silane saturation supply of 10%. The deposition rate achieved in this experiment was 0.2 mm / h.

With this because of the lack of current flow and the deeper Temperature low deposition rate was a pure degree reached after crystallization by a Resistance value of 2000 Ωcm (n-type) was characterized. The metal levels were undetectable since they were out were consistently below the detection limit. The purity s, ': 22'Metals can, however, by the particularly long life of the minority charge carriers that describe 5000 µsec wore.

A particular advantage of this deposition process is that the low temperature means that the deposition only takes place on the silicon rod, while a gas phase decomposition of the easily decomposable silane (SiH ₄ ) was not observed.

Example 4

A reactor with an inner diameter of 250 mm and one Height of 1000 mm was built up. The lower part of the reak tors was separated using a fine perforated plate. Through this perforated plate, one became from below Mixture of silane and hydrogen existing gas stream so blown in that the silicon on the perforated plate Granules with a grain size of 300 µm with approx. 200 mm bulk height was kept in slight movement. After the scarf ten of the microwave generators with a total output of 5 kW via laterally arranged waveguides in the upper part the silicon granulate was 10 minutes before the fluidized bed heated. The temperature reached was sufficient to reacting silane diluted with hydrogen and To deposit silicon on the grains of the silicon granulate the. During the deposition, the microwave power could can be reduced to approx. 2 kW. The advantage is that neither the reactor wall heated by resistance heating electrical current flow in the fluidized bed had to become. The arrangement of the microwave guides be preferably in the upper part, the fluidized bed was also a thermal caking or a reactive coalescence of the Si grains avoided.

The gas mixture used contained 5% silane, which at over 98% of the reaction to silicon and hydrogen was set, as by gas chromatographic determination of the exhaust gas components or the volume increase of the silicon Granules was determined.

Claims (19)

1. Apparatus for the deposition of pure semiconductor material, in particular silicon, by thermal decomposition of gaseous compounds of this semiconductor material on heated support bodies, which absorb electromagnetic radiation with heating, in a deposition reactor consisting of a metallic base plate with nozzles for the feed and Removal of gases and a coolable bell placed over it and sealed at the edge with the base plate in a coolable manner characterized by

• a) at least one generator arranged outside the reactor for generating electromagnetic waves, where they are radiated into the reactor at several points
• b) a reactor inner wall made of a material which reflects the incident electromagnetic waves almost without loss.

2. Device according to claim 1, characterized in that the path of the electromagnetic waves from the generator to the Reactor passes at least through a membrane that is full always permeable to the used electromagnetic is radiation and on which no deposition of the Semiconductor material takes place.   3. Device according to claim 2, characterized in that the electromagnetic radiation through 4 to 8 membranes is irradiated into the reactor housing. 4. The device according to one or more of claims 2 and 3, characterized in that the membrane is preferred as coolable quartz windows. 5. The device according to one or more of claims 1 to 4, characterized in that the transmission of the elec tromagnetic waves from the generator to the reactor a waveguide is made. 6. The device according to one or more of claims 1 to 5, characterized in that the generator for elec tromagnetic waves microwave generated. 7. The device according to claim 6, characterized in that the generator microwaves of the frequency 0.5-3.0 GHz generated. 8. The device according to one or more of claims 1 to 7, characterized in that the support body from half conductor material through brackets, in particular from Gra phit, are attached to the metallic base plate. 9. The device according to one or more of claims 1 to 8, characterized in that the semiconductor material in Form of thin rods in the reactor, two each Brackets with supply and discharge lines for elec connect electrical current. 10. The device according to one or more of claims 1 to 7, characterized in that the bottom of the reactor consists of a perforated plate through the openings of which  Process gas flows in and the support body, consisting of a semiconductor granulate keeps moving. 11. The device according to one or more of claims 1 to 10, characterized in that the reactor room closing surfaces of the reactor housing made of silver or Silver-plated steel are made. 12. Process for the deposition of pure semiconductor material, especially silicon, by thermal decomposition gas shaped connections of this semiconductor material heated support bodies in a device according to one or more of claims 1 to 11, characterized net in that the heating of the material of the stretcher body by electromagnetic radiation from several Sources are homogeneous. 13. The method according to claim 12, characterized in that the deposition is carried out by thermal decomposition of silane, SiH ₄ , in particular from SiH ₄ / H ₂ mixtures. 14. The method according to claim 12, characterized in that the deposition from a mixture of trichlorosilane and Hydrogen occurs. 15. The method according to one or more of claims 12 to 14, characterized in that the heating of the mate rials of the carrying body by electromagnetic radiation up to the limit temperature at which a Re flexion of electromagnetic radiation by the Semiconductor material of the support body is made.   16. The method according to one or more of claims 12 to 15, characterized in that the heating by electromagnetic radiation in a temperature range of up to 650 ° C. 17. The method according to one or more of claims 13, 15 or 16 using the device of claim 10, characterized in that the granules from half conductor material through a flow of the process gas the perforated plate is kept in motion. 18. The method according to claim 17, characterized in that which is a homogeneous irradiation of the electromagnetic Radiation takes place in a reaction zone that is 100-500 mm lies above the perforated plate. 19. The method according to one or more of claims 12 to 16, characterized in that tilting mirrors serve to the electromagnetic generated by a generator Move radiation to several different reactors to steer.