The present invention relates to an apparatus and a method for producing polycrystalline silicon having a reduced amount of boron compound impurities. Especially, the boron compounds are removed from the process for producing polycrystalline silicon, while the trichlorosilane is purified by distillation. The invention feeds condensed liquid trichlorosilane into a primary distillation tower below the liquid level inside the primary distillation tower thereby scrubbing the boron impurities upon contact inside the primary distillation tower. There result is trichlorosilane leaving the primary distillation tower with total amount of boron at least 10 times less.

A system for extracting liquid is provided. The system includes a vacuum source and a nozzle having a wettable plunger and a vacuum tube connected in flow communication with the vacuum source. When the plunger is partly submerged in the liquid and the vacuum source is actuated to initiate a flow of gas through the vacuum tube, droplets of the liquid separate from at least a portion of the unsubmerged part of the plunger and become suspended in the gas flow. The system also includes a cooling structure positioned adjacent to the vacuum tube to facilitate solidifying the droplets suspended in the gas flowing through the vacuum tube.

A thermoelectric conversion material is used in which columnar or spherical nanodots 1 having a diameter of 20 nm or less are embedded in an embedding layer 3 at an area density of 5?10.sup.10/cm.sup.2 or more and an interval between the nanodots of 0.5 nm or more and 30.0 nm or less, and the first material constituting the nanodot 1 is a material containing silicon in an amount of 30 atom % or more, and, either one or both of a difference in energy between the valence band of the first material and the valence band of the second material constituting the embedding layer 3 and a difference in energy between the conduction band of the first material and the conduction band of the second material constituting the embedding layer are in the range of 0.1 eV or more and 0.3 eV or less.

The present invention relates to an apparatus and a method for producing polycrystalline silicon having a reduced amount of boron compound impurities. Especially, the boron compounds are removed from the process for producing polycrystalline silicon, while the trichlorosilane is purified by distillation. The invention feeds condensed liquid trichlorosilane into a primary distillation tower below the liquid level inside the primary distillation tower thereby scrubbing the boron impurities upon contact inside the primary distillation tower. There result is trichlorosilane leaving the primary distillation tower with total amount of boron at least 10 times less.

The present invention relates to an apparatus and a method for producing polycrystalline silicon having a reduced amount of boron compound impurities. Especially, the boron compounds are removed from the process for producing polycrystalline silicon, while the trichlorosilane is purified by distillation. The invention feeds condensed liquid trichlorosilane into a primary distillation tower below the liquid level inside the primary distillation tower thereby scrubbing the boron impurities upon contact inside the primary distillation tower. There result is trichlorosilane leaving the primary distillation tower with total amount of boron at least 10 times less.

The present invention is for the recovery of maximum silicon value of kerf silicon waste, produced during the manufacture of silicon wafers by wire saw, diamond saw and chemical mechanical polishing, as high purity metallurgical silicon. This recovery is achieved by a process scheme that effects an initial removal of minor extrinsic metallic impurities but not the major silicon compound impurities, and followed, preferentially, by a direct metallurgical process to form elemental silicon. The recovered silicon is for use as feedstock for polysilicon manufacturing, as high purity polysilicon for PV application, and in metallurgical alloy manufacture.

The present invention is for the recovery of maximum silicon value of kerf silicon waste, produced during the manufacture of silicon wafers by wire saw, diamond saw and chemical mechanical polishing, as high purity metallurgical silicon. This recovery is achieved by a process scheme that effects an initial removal of minor extrinsic metallic impurities but not the major silicon compound impurities, and followed, preferentially, by a direct metallurgical process to form elemental silicon. The recovered silicon is for use as feedstock for polysilicon manufacturing, as high purity polysilicon for PV application, and in metallurgical alloy manufacture.

The invention provides a method for purifying silicon by means of a phase separation dealloying reaction, including: mixing a silicon raw material containing metallic or non-metallic impurities with magnesium powder first and then fully reacting under an inert atmosphere so as to obtain a first product; placing the first product in a nitrogen-containing atmosphere to undergo a nitriding reaction to form three-dimensional porous silicon and magnesium nitride distributed in pore channels thereof so as to obtain a second product, the impurities further being separated during the precipitation and crystallization of silicon, and being dissolved in the liquid-phase magnesium nitride; treating the second product by using acid-pickling, the magnesium nitride and impurities being dissolved and converted into a solution, and a solid product being high-purity porous silicon.

The invention provides a method for purifying silicon by means of a phase separation dealloying reaction, including: mixing a silicon raw material containing metallic or non-metallic impurities with magnesium powder first and then fully reacting under an inert atmosphere so as to obtain a first product; placing the first product in a nitrogen-containing atmosphere to undergo a nitriding reaction to form three-dimensional porous silicon and magnesium nitride distributed in pore channels thereof so as to obtain a second product, the impurities further being separated during the precipitation and crystallization of silicon, and being dissolved in the liquid-phase magnesium nitride; treating the second product by using acid-pickling, the magnesium nitride and impurities being dissolved and converted into a solution, and a solid product being high-purity porous silicon.