667 results about "Molten silicon" patented technology

Method capable of preparing silicon having purity of about 6N applied to a solar cell efficiently at a low cost. Raw silicon containing boron and a slag are melted and a shaft is rotated by a rotating / driving mechanism for stirring the molten silicon. The molten slag is dispersed in the molten silicon, thereby accelerating the boron removal reaction. It is further effective to use a slag containing at least 45 percent by mass of silicon oxide or to blow gas mixed with water vapor into the molten silicon for refining reaction.

A composite material featuring carbon nanotubes reinforcing a matrix featuring metal or silicon carbide, or both. Such composites can be produced using a molten silicon metal infiltration technique, for example, a siliconizing or a reaction-bonding process. Here, the carbon nanotubes are prevented from chemically reacting with the silicon infiltrant by an interfacial coating disposed between the carbon nanotubes and the infiltrant. Preferably, the coating is free carbon or a carbonaceous precursor material added during preform processing, or after. The reaction-bonding system is designed such that the molten infiltrant of silicon metal or silicon alloy reacts with at least some of the interfacial carbon layer to form in-situ silicon carbide, and that the formed SiC is sufficiently dense that it effectively seals off the underlying carbon nanotube from exposure to additional molten infiltrant. A reaction-bonded composite body containing even a small percentage of carbon nanotubes possessed a significant increase in electrical conductivity as compared to a reaction-bonded composite not containing such nanotubes, reflecting the high electrical conductivity of the nanotubes.

The invention relates to an abrasive compact comprising a mass of diamond particles and a silicon containing binder phase wherein the diamond particles are present in an amount less than 75 volume % and the binder phase contains less than 2 volume % unreacted (elemental) silicon. The invention further relates to a method of producing an abrasive compact including the steps of forming a feed diamond powder into a diamond preform, interposing a separating mechanism between the diamond preform and a silicon infiltrant source, heating the diamond preform and silicon infiltrant source until the infiltrant is molten and the preform and infiltrant are isothermal and allowing infiltration from the molten silicon infiltrant source to occur into the diamond preform.

A silicon semiconductor substrate is obtained by deriving a silicon semiconductor substrate from a silicon single crystal grown by the Czochralski method from a molten silicon containing not less than 1x1016 atoms / cm3 and not more than 1.5x1019 atoms / cm3 of nitrogen and heat-treating the silicon semiconductor substrate at a temperature of not less than 1000° C. and not more than 1300° C. for not less than one hour and is characterized by the fact that the density of crystal defects measuring not less than 0.1 mum as reduced to diameter is not more than 104 pieces / cm3 at least in the region reaching a depth of 1 mum from the surface of the substrate and the nitrogen content at the center of thickness of the silicon semiconductor substrate is not less than 1x1013 atoms / cm3 and not more than 1x1016 atoms / cm3.

Disclosed are a purification device as well as a purification method of solar-grade polysilicon, relating to a polysilicon, which provides a purification device and a purification method of solar-grade polysilicon characterized by low cost, high purity, simple process, easy operation and suitability for large-scale production. The purification device is equipped with a vacuum system, a melting system and a directional solidification system; wherein the vacuum system is provided with a mechanical rotary vane pump, a lobed element pump and an oil diffusion pump, and the melting system is provided with a vacuum chamber, a secondary feeder, an observation window, a rotary ventilation device which can be raised and lowered, an induction coil and a graphite crucible; and the directional solidification system is disposed at the lower part of the vacuum chamber and is equipped with an electric resistance-wire heating and holding furnace, a graphite mold, a holding furnace frame, a water-cooled copper tray and an elevating lever which can control speed. The metal silicon is treated by induction heating to be molten, the oxidizing gas is fed under conditions of low vacuum and high temperature to remove boron, and then under conditions of high temperature and high vacuum to remove phosphorus, and finally the molten silicon solution is poured into a directional mold to strictly conduct directional solidification to remove metal impurities.

An improved system based on the Czochralski process for continuous growth of a single crystal ingot comprises a low aspect ratio, large diameter, and substantially flat crucible, including an optional weir surrounding the crystal. The low aspect ratio crucible substantially eliminates convection currents and reduces oxygen content in a finished single crystal silicon ingot. A separate level controlled silicon pre-melting chamber provides a continuous source of molten silicon to the growth crucible advantageously eliminating the need for vertical travel and a crucible raising system during the crystal pulling process. A plurality of heaters beneath the crucible establish corresponding thermal zones across the melt. Thermal output of the heaters is individually controlled for providing an optimal thermal distribution across the melt and at the crystal / melt interface for improved crystal growth. Multiple crystal pulling chambers are provided for continuous processing and high throughput.

PCT No. PCT / FR96 / 01598 Sec. 371 Date May 13, 1998 Sec. 102(e) Date May 13, 1998 PCT Filed Oct. 14, 1996 PCT Pub. No. WO97 / 18176 PCT Pub. Date May 22, 1997A plurality of substrates (10) are disposed in alternation and in contact with layers (12) which constitute sources of metal-based composition, each layer comprising a majority phase formed by the metal-based composition and a minority phase suitable for forming a structure for retaining and draining the metal-based composition when it is in the molten state. The batch is heated to a temperature greater than the melting temperature of the metal-based composition such that the metal-based composition in the molten state can migrate from each source through the adjacent surface of the, or each, substrate adjacent to the source towards the inside of the substrate. The invention seeks in particular to incorporate a silicon-based composition in a thermostructural composite material, in particular a carbon-carbon composite material for siliciding purposes.

A composite material featuring comminuted or otherwise well dispersed and separated nanotubes reinforcing a matrix featuring metal, ceramic and / or polymer. In a preferred embodiment, the nanotubes feature elemental carbon, and the composites can be produced using a molten silicon metal infiltration technique, which may be pressurized or not, for example, a siliconizing or a reaction-bonding process. In this preferred embodiment, carbon nanotubes may be prevented from chemically reacting with the silicon infiltrant by an interfacial coating disposed between the carbon nanotubes and the infiltrant. A reaction-bonded composite body containing even a small percentage of carbon nanotubes possessed a significant increase in electrical conductivity as compared to a reaction-bonded composite not containing such nanotubes, reflecting the high electrical conductivity of the nanotubes. When the nanotubes are well dispersed throughout the preform, mechanical property enhancements start to become noticeable, such as fracture toughness enhancement.

A method of manufacturing a part out of impervious thermostructural composite material, the method comprising forming a porous substrate from at least one fiber reinforcement made of refractory fibers, and densifying the reinforcement by a first phase of carbon and by a second phase of silicon carbide. The method then continues by impregnating the porous substrate with a composition based on molten silicon so as to fill in the pores of the substrate.

Provided are a method of forming a polycrystalline silicon thin film with improved electrical characteristics and a method of manufacturing a thin film transistor using the method of forming the polycrystalline silicon thin film. The method includes forming an amorphous silicon thin film on a substrate, partially melting a portion of the amorphous silicon thin film by irradiating the portion of the amorphous silicon thin film with a laser beam having a low energy density, forming polycrystalline silicon grains with a predetermined crystalline arrangement by crystallizing the partially molten portion of the amorphous silicon thin film, completely melting a portion of the polycrystalline silicon grains and a portion of the amorphous silicon thin film by irradiation of a laser beam having a high energy density while repeatedly moving the substrate by a predetermined distance, and growing the polycrystalline silicon grains by crystallizing the completely molten silicon homogeneously with the predetermined crystalline arrangement.

The invention discloses a method for manufacturing carbon / ceramic braking linings used in an industrial brake, which comprises the following steps: carbon fiber performs are prepared by a needle method; low-density C / C composite material is prepared by a chemical gas permeation method after the carbon fiber performs are treated in high temperature; the C / C composite material is treated in high temperature, machined and then the molten silicon infiltration is carried out on the C / C material in a high temperature vacuum furnace; Sic is formed by the Si and C reaction to prepare C / C-SiC baking material; and finally after the C / C-SiC baking material is machined, the C / C-SiC baking material is riveted with the steel backing by a rivet in a cold way to prepare the needed C / C-SiC baking material used in an industrial brake. The carbon / ceramic braking lining manufactured by the method has higher mechanical property and excellent frictional wear performance and is used in the industrial brake.

A method of melt infiltrating a fiber-reinforced ceramic matrix composite preform includes (a) dipping the preform into a bath of molten Silicon; (b) leaving the preform in the bath for a predetermined time; (c) withdrawing the preform from the bath; and (d) cooling the preform.

In order to efficiently recycle a silicon scrap obtained by cutting a silicon chunk as a raw material silicon for solar batteries, a silicon recycling method of the present invention, according to one aspect, includes the steps of melting a silicon scrap by heating, and immersing a crystallization substrate in molten silicon and depositing silicon on a surface of the crystallization substrate. The step of separating silicon on the surface of the crystallization substrate from the crystallization substrate is preferably included. In addition, a silicon ingot obtained by melting the silicon raw material for solar batteries in a mold and solidifying the same is suitable as the silicon chunk.

An improved system based on the Czochralski process for continuous growth of a single crystal ingot comprises a low aspect ratio, large diameter, and substantially flat crucible, including an optional weir surrounding the crystal. The low aspect ratio crucible substantially eliminates convection currents and reduces oxygen content in a finished single crystal silicon ingot. A separate level controlled silicon pre-melting chamber provides a continuous source of molten silicon to the growth crucible advantageously eliminating the need for vertical travel and a crucible raising system during the crystal pulling process. A plurality of heaters beneath the crucible establish corresponding thermal zones across the melt. Thermal output of the heaters is individually controlled for providing an optimal thermal distribution across the melt and at the crystal / melt interface for improved crystal growth. Multiple crystal pulling chambers are provided for continuous processing and high throughput.

A fiber-reinforced silicon carbide composite is produced by preparing a fiber prepreg containing a powdered silicon and a resin and molding the prepreg to yield a green body having a desired shape, or laminating a fiber prepreg containing a resin and a woven fabric prepreg containing a powdered silicon and a resin in alternate order and molding the laminate to yield a green body having a desired shape; carbonizing the green body at 900° to 1350° C. in an inert atmosphere; subjecting the carbonized body to reaction sintering at a temperature of 1300° C. or more in vacuo or in an inert atmosphere to form open pores; and infiltrating molten silicon into the sintered body having open pores at a temperature of about 1300° to 1800° C. in vacuo or an inert atmosphere.

In a refining method for boron-containing silicon, boron-containing silicon is irradiated with an electron beam in a vacuum vessel to melt the boron-containing silicon. A boron compound-forming substance is introduced into the vacuum vessel, and boron contained in the molten silicon is formed into a boron compound. After at least a portion of the boron compound has vaporized, irradiation with the electron beam is stopped. The high-purity molten silicon can then be solidified.

Nitrogen and aluminum and fluxing agents (Al2O3, SiO2, CaO and MgO) are added to molten silicon to create an oxy-nitride slag that acts as a sink for dissolved boron and phosphorus. The nitrogen can be added by bubbling nitrogen gas through the molten silicon; the aluminum can be added as aluminum metal or as Al2O3. Normally, the silicon must initially be deoxidized to allow the boron and phosphorus refining reactions to occur. The process may be followed by oxidative refining, SiC settling, the Silgrain process and directional solidification to remove other impurities and produce silicon suitable for use in solar cells. In an alternative version of the process, the molten silicon is passed through a particulate bed formed of a nitrogen-containing compound and an aluminum-containing compound.

A method for using substantial quantities of silicon powders as charge and processing it to produce a high quality silicon ingots suitable for photovoltaic use is disclosed. In a fused silica crucible, silicon feedstock containing more than about 5% by weight silicon powder is charged. The crucible with the charged silicon feedstock is placed into a furnace chamber and a vacuum is drawn to remove air. The vacuum is applied slowly. Then, the furnace chamber is backfilled with argon gas and heated to form molten silicon. Afterward, the molten silicon is solidified and annealed to form a multicrystalline silicon ingot.

The present invention provides a method for removal of boron from metal silicon inexpensively and extremely efficiently by a simple method, specifically, heating metal silicon containing boron as an impurity to its melting point to 2200° C. to place it in a molten state, then adding a solid mainly comprised of silicon dioxide and a solid mainly comprised of one or both of a carbonate of an alkali metal or a hydrate of a carbonate of an alkali metal into said molten silicon so as to form a slag and remove the boron in the silicon.

A method of making a carbon fiber-carbon matrix reinforced ceramic composite wherein the result is a carbon fiber-carbon matrix reinforcement is embedded within a ceramic matrix. The ceramic matrix does not penetrate into the carbon fiber-carbon matrix reinforcement to any significant degree. The carbide matrix is a formed in situ solid carbide of at least one metal having a melting point above about 1850 degrees centigrade. At least when the composite is intended to operate between approximately 1500 and 2000 degrees centigrade for extended periods of time the solid carbide with the embedded reinforcement is formed first by reaction infiltration. Molten silicon is then diffused into the carbide. The molten silicon diffuses preferentially into the carbide matrix but not to any significant degree into the carbon-carbon reinforcement. Where the composite is intended to operate between approximately 2000 and 2700 degrees centigrade for extended periods of time such diffusion of molten silicon into the carbide is optional and generally preferred, but not essential.

Techniques for controlling resistivity in the formation of a silicon ingot from compensated feedstock silicon material prepares a compensated, upgraded metallurgical silicon feedstock for being melted to form a silicon melt. The compensated, upgraded metallurgical silicon feedstock provides a predominantly p-type semiconductor for which the process assesses the concentrations of boron and phosphorus and adds a predetermined amount of aluminum or / and gallium. The process further melts the silicon feedstock together with a predetermined amount of aluminum or / and gallium to form a molten silicon solution from which to perform directional solidification and, by virtue of adding aluminum or / and gallium, maintains the homogeneity the resistivity of the silicon ingot throughout the silicon ingot. In the case of feedstock silicon leading to low resistivity in respective ingots, typically below 0.4Ω cm, a balanced amount of phosphorus can be optionally added to aluminum or / and gallium. Adding phosphorus becomes mandatory at very low resistivity, typically close to 0.2Ω cm and slightly below.

Production of photovoltaic grade crystalline silicon is achieved by crystallization of a molten silicon feedstock, the sum of the initial donor doping element and acceptor doping element concentrations whereof is greater than 0.1 ppma, and both the acceptor and donor doping element concentrations whereof are less than 25 ppma. At least a predefined quantity of a doping material having a segregation coefficient of less than 0.1 is added to the feedstock. This addition enables a crystallized silicon to be produced the difference between the donor and acceptor doping profiles whereof is comprised between 0.1 and 5 ppma over at least 50% of the solidified silicon. A silicon presenting a concentration of at least one of the dopants is greater than or equal to 5 ppma and a difference less than or equal to 5 ppma between these two types of dopant is integrated in a photovoltaic cell.

The invention relates to a molten silicon liquid level position control method of a CZ-Si single crystal furnace. The invention comprises the following steps: heat shield inverted image data is obtained; the data is processed to obtain D; D is compared with D0, D-D0 difference value is inputted into an analog / digital converter to be an electric signal for controlling the speed raising of a vortex increasing motor, to increase or decrease the speed of the vortex increasing motor; a feed back circuit integrates the increase speed increment, and a practical D value is obtained; a computer calculates a D-D0 difference value, if the D-D0 difference value is 0, the proportion of the rising speed of the vortex increasing motor and the crystal increasing speed is not changed; or else, the proportion is increased or decreased (according to the plus minus of the D-D0 difference value). The method has the advantages that the operation is convenient, the precision is high, if the method is used, the variety of the defaults in a CZ-Si single crystal and the distribution of the CZ-Si single crystal can be controlled.

The invention provides a preparation method of polycrystalline silicon ingots. The preparation method comprises the following steps: before or after the inner wall of a crucible is sprayed with a silicon nitride layer, a barrier layer is arranged on the inner side of the side wall of the crucible, wherein the barrier layer is a silicon powder coating layer, or a quartz powder coating layer, or a silicon powder and quartz powder mixed coating layer, and purities of silicon powder and quartz powder are above 99.99%; then a molten silicon material is arranged in the crucible; temperature in the crucible is controlled to increase gradually, along a direction which is perpendicular to the bottom of the crucible and is upward, to form a temperature gradient to make the molten silicon material to begin crystallization; and after the crystallization is finished, and the polycrystalline silicon ingots are obtained through annealing and cooling . The invention also provides the high quality polycrystalline silicon ingots obtained by the preparation method, and polycrystalline silicon chips prepared from the polycrystalline silicon ingots and the polycrystalline silicon ingot casting crucible. The polycrystalline silicon ingots prepared by the preparation method are characterized in that crystalline grains near areas of crucible wall are smaller, uniform and regular, dislocation density is low, and impurities is less.

A process for preparing a silicon melt from a polysilicon charge, for use in the production of single crystal silicon ingots by the Czochralski method, in a crucible which has a bottom, a sidewall formation, a centerline which is substantially parallel to the sidewall formation and which intersects a geometric centerpoint of the bottom, and a radius extending from the centerline to the sidewall formation. In the process, the crucible is loaded with chunk polysilicon to form a charge having a bowl-like shape, wherein initially the load generally slopes radially upwardly and outwardly from the centerline toward the sidewall formation to an apex and then slopes generally downwardly and outwardly from the apex to the sidewall formation. The bowl-shaped chunk polysilicon charge is heated to form a partially melted charge, and granular polysilicon is fed onto the partially melted charge to form a mixed charge of chunk and granular polysilicon. As the mixed charge is further heated to form a silicon melt, the unmelted chunk polysilicon present above the melt surface acts to deflect any molten silicon that may be splattered as granular polysilicon rapidly melts and hydrogen is released.

The invention discloses an MgB2 superconducting magnet for magnetic-control Czochralski (CZ) processing of a monocrystal. The MgB2 superconducting magnet for the magnetic-control CZ processing of the monocrystal comprises a low-temperature container, wherein a refrigerator is arranged on the low-temperature container. The MgB2 superconducting magnet for the magnetic-control CZ processing of the monocrystal has the advantages of being high in magnetic field intensity, low in manufacturing cost, simple in system, low in power consumption, easy to operate and the like. Due to the fact that heat convection of molten silicon is effectively limited, the produced monocrystal silicon has higher purity and uniformity, and the defects of oxygen and dots in the position of an interface of the crystal melt and other impurities are effectively controlled.

The invention discloses a method for preparing solar energy level silicon crystals containing doped element, which is to place molten silicon containing the doped element into a crucible reactor and adopt a directional solidification method or a pulling method to prepare the silicon crystals. In the preparation process of the silicon crystals, protective gas is introduced into a crystal growing furnace and flows through the surface of the molten silicon, and is as follows: a) gas containing hydrogen atoms; or b) a mixture of the gas containing the hydrogen atoms and inert gas. The method obviously improves the minority-carrier lifetime of the silicon crystals by the functions of H on passivation, gettering and the like of impurities and defects in the silicon crystals, and improves the photoelectric conversion efficiency of subsequently manufactured cell slices. The method also adjusts the resistivity of silicon crystals doped with gallium and makes the resistivity of the silicon crystals more uniform in the crystal growing direction. Moreover, the method is simple in operation and easy in industrialized production, and can obviously improve the product quality.

The invention discloses a charging method in monocrystalline silicon ingot casting. The method comprises the steps that: a plurality of seed crystals are placed on a bottom surface of a crucible; one or more filling materials with a melting point no lower than that of silicon is filled in gaps among the seed crystals and between the seed crystals and a crucible wall; and a silicon raw material used in ingot casting is placed on the surface of the seed crystals. The invention also provides a monocrystalline silicon ingot casting method. With the method, when the silicon raw material is filled into the crucible, the filling materials with the melting point no lower than that of silicon is filled in gaps among the seed crystals and between the seed crystals and the crucible wall. Therefore, when the silicon raw material is molten, the molten silicon is prevented from entering the gaps among the seed crystals and between the seed crystals and the crucible wall, so that seed crystal floating and melting caused by the molten silicon are prevented. According to the value of silicon raw material thermal conductivity, a leveled charging method is adopted, so that temperature gradient during a monocrystalline silicon ingot casting procedure is increased. Therefore, molten silicon is prevented from contacting the seed crystals in a premature stage, and seed crystals can be prevented from melting too fast. Therefore, difficulty in controlling monocrystalline silicon ingot casting process can be prevented.

The invention is directed to a method of producing polycrystaline silicon metal from a silicon halide plasma source. The silicon halide is split into silicon and halide ions in an inductively coupled plasma and silicon ions are then condensed to form molten silicon metal that can be vacuum cast into polysilicon ingots. The halide ions are separated and recycled into silicon halide gas over a silicon dioxide bed. In this way, high grade polysilicon is produced without a metallurgical grade silicon precursor and the process these processes consumes the byproducts in a continuous manner madding it less expensive than traditional methods of producing polysilicon and more environmentally friendly.