Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B33/00—Silicon; Compounds thereof
  • C01B33/02—Silicon
  • C01B33/021—Preparation
  • C01B33/027—Preparation by decomposition or reduction of gaseous or vaporised silicon compounds other than silica or silica-containing material
  • C01B33/035—Preparation by decomposition or reduction of gaseous or vaporised silicon compounds other than silica or silica-containing material by decomposition or reduction of gaseous or vaporised silicon compounds in the presence of heated filaments of silicon, carbon or a refractory metal, e.g. tantalum or tungsten, or in the presence of heated silicon rods on which the formed silicon is deposited, a silicon rod being obtained, e.g. Siemens process
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
  • C23C16/455—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for introducing gases into reaction chamber or for modifying gas flows in reaction chamber

Definitions

• High-purity polycrystalline silicon serves as a starting material for the production of single-crystal silicon for semiconductors according to the Czochralski (C) - or zone melting (FZ) - method, as well as for the production of on or
• Multicrystalline silicon according to various drawing and casting processes for the production of solar cells for photovoltaics.
• Polysilicon is usually produced by means of the Siemens process.
• a reaction gas comprising one or more silicon-containing components and optionally hydrogen in a reactor comprising by direct
• Silicon-containing components are preferably silane (SiH4), monochlorosilane (SiH3Cl), dichlorosilane (SiH2C12), trichlorosilane (SiHC13), tetrachlorosilane (SiCl4) or mixtures of the substances mentioned.
• the Siemens procedure is usually in one
• the reactor comprises a metallic baseplate and a coolable bell placed on the baseplate so that a reaction space within the reaction chamber is provided
• the baseplate is provided with one or more gas inlet openings and one or more
• Each carrier body usually consists of two thin ones
• Filament rods and a bridge which is usually adjacent Joining rods at their free ends.
• the filament rods are made of single or polycrystalline silicon
• the filament rods are mounted vertically in electrodes located at the bottom of the reactor, via which the connection to the power supply takes place. High-purity precipitates on the heated filament rods and the horizontal bridge
• JP 2002241120 A2 discloses a separation reactor in which reaction gas is introduced at the top. The reaction gas mixes above the silicon rod with ascending
• Reactor center injected. By natural convection on the hot rod surface ascending reaction gas should mix with cold sloping fresh gas. The sloping
• Fresh gas causes a countercurrent to the doughy
• DD 64047 A describes a process for the preparation of
• AT 220591 B discloses a vessel for producing high-purity silicon, in which the feed passes along various
• CN 201313954 Y discloses a separation reactor in which reaction gas is injected centrally from above and laterally from below. Due to the generated gas flow, the thickness of the
• Gas boundary layer can be reduced on the silicon rod.
• the method is that the opposing gas flows from below and above cancel their gas pulses. This leads to thicker boundary layers on the silicon rods, the one
• Separating reactors are used, in which the reaction gas is injected via nozzles in the lower part, the so-called bottom plate.
• Rods with cracks and spalling can cause electrical
• the energy consumption at separation plants is u.a. caused by the convective release of heat via the reaction gas to the cooled reactor wall.
• the reaction gas is to be introduced into the reactor so that the largest possible feed mass flow causes a lower thermal stress on the rods.
• Filament rods are attached, which are heated, wherein by means of gas inlet openings on the reactor wall and in the
• the gas inlet openings are bores.
• the geometry of the hole can be chosen arbitrarily. The invention will be explained below with reference to FIGS. 1-8.
• a bore may have two different angles to the side wall of the reactor. Such an embodiment is shown in FIG. 3. Both the minimum bore angle and the maximum bore angle may vary only in the 0-45 ° angle range to ensure that the reaction gas mixture is introduced at an angle of 0-45 ° to the side wall of the reactor.
• reaction gas mixture is introduced at an angle of 0-45 ° to the lateral reactor wall, a wall film is simultaneously produced, which significantly reduces the convective heat exchange with the reactor wall.
• this wall film is a closed gas film, which is formed from the externally injected reaction gas and along the
• Reactor inner wall flows from top to bottom.
• the reactor has a bell-shaped geometry (cylinder +
• the uppermost inlet openings are in a range between 40% and 100% of the height above the base plate relative to the height of the vertical reactor wall, preferably between 70% and 100%.
• Aj.ni. corresponds to a surface of an inlet opening on the reactor wall
• a Reac corresponds to a cross-sectional area of the
• Reactor formed with the reactor inner diameter D, so
• the inlet openings are distributed uniformly over the circumference, but they can also be arranged unevenly.
• the bore shape is usually circular but may have other shapes (e.g., elliptical or the like) and combinations thereof.
• the direct distance a of the bores (outer edge to outer edge, see FIGS. 4 to 6) relative to one another is at least 3 mm, preferably at least 10 mm, particularly preferably at
• the rows of holes can be single or multiple, possibly
• FIGS. 5 and 7 are identical to FIGS. 5 and 7.
• the combination of 2 to 4 rows of holes to a hole block more preferably 2 - 3 rows of holes (see Fig. 7).
• the vertical distance "b" of adjacent rows of holes is preferably at most 5 reference bore diameters (see FIG. 5).
• Diameter of all individual bores on the vertical reactor wall with D H hydraulic reference bore diameter
• Ai cross-sectional area of the single bore i on the vertical reactor wall
• Particularly preferred are 2-4 bore blocks.
• the distance 1 of the blocks satisfies 0.2 ⁇ 1 / D ⁇ 0.8;
• a partial amount of the reaction gas is introduced via nozzles on the bottom plate of the reactor.
• the reaction gas which is introduced via the bottom plate, flows through at least one nozzle in the center and possibly
• Floor plate can be dispensed with.
• reaction gas is introduced, is preferably between 30 and 100 Percent by mass, more preferably 50-90% by mass, in each case based on the total addition of reaction gas.
• An optimized injection is achieved by a variable to be designed during the process quantity distribution between base plate and wall.
• the wall film produced is ideally adapted to the changing flow conditions in the reactor.
• This selective introduction of the fresh gas directed down the inside of the reactor influences the wall film (i.e., the downward flow of gas near the wall) such that the total energy demand of the reactor drops significantly.
• An essential advantage of the invention is that the circulation flow in the reactor is maintained.
• the reactor according to JP2002241120 A2 for example, the
• Circulation flow of the reaction gas is not promoted, but obstructed.
• the reactor internal diameter was in each case 1.7 ⁇ m in each case.
• the deposition temperature was in the batch process between 1000 ° C and 1100 ° C.
• the wall film is perpendicular to the bottom, tangential to the cylindrical portion of the bell wall
• the injection was made possible by a recessed step with 240 cylindrical injections distributed around the circumference.
• the mass fraction of the mass flow at the wall was made possible by a recessed step with 240 cylindrical injections distributed around the circumference.
• CVD reactor equipped with variant A of FIG. 2. Positioning of the bores according to FIG. 4.
• the wall film is introduced via a row with 180 holes distributed at the circumference at an angle of 25 °.
• the distance between the inlet holes and the base plate was 2.0m.
• Total mass flow was between 50% and 90% depending on the deposition time (starting at 50%, ending at 90%).
• the wall film is placed over two blocks of offset rows of holes of 360 holes at an angle of 20 ° on the bell wall in the reactor.
• Each block consists of 3 rows of holes, each with 120 holes.
• the rows of holes each had a vertical distance of 3 hole diameters from each other.
• the ratio 1 / D was 0.5.
• Bore block was 2.2 m.
• Bore block to the bottom plate was 1.35 m.
• the mass flow rate applied to the wall ranged from 50% to 90% depending on the deposition time (starting at 50%, ending at 90%).
• Power consumption measured on average 11% compared to the injection of the total amount of feed through the bottom plate.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Silicon Compounds (AREA)
• Chemical Vapour Deposition (AREA)
• Crystallography & Structural Chemistry (AREA)
• Physics & Mathematics (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• General Physics & Mathematics (AREA)
• Manufacturing & Machinery (AREA)
• Computer Hardware Design (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Power Engineering (AREA)

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