JP2727728B2 - Pure substance production apparatus and pure substance production method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an apparatus for producing a pure substance and a method for producing a pure substance. More specifically, the present invention relates to a method for producing an impurity from a pure substance based on a difference between a mass and a charge of the substance. The present invention relates to an apparatus and a method for producing a pure substance for producing a high-purity substance by separating a substance.

<Prior Art> Conventionally, attempts have been made to increase the purity of various metal materials for the purpose of improving their functional characteristics.

At present, the most advanced method for producing a pure substance is a method for producing silicon. The purity of silicon deposited by this production method is about 99.9999999% (nine nine).

 Hereinafter, a method for producing high-purity silicon will be described.

First, silica ore (SiO ₂ ), which is an ore, is heated in an electric furnace together with coke or charcoal, and metallic silicon is obtained by a reduction reaction represented by the formula.

The purity of the silicon obtained at this stage is up to about 99.5%.

SiO ₂ + 2C = Si + 2CO... Silicon used as a semiconductor must be extremely pure. For this reason, the metal silicon obtained as described above is further reacted with chlorine or chlorine gas to separate the silicon tetrachloride (SiCl ₄ ) or silane trichloride (SiHCl ₃ ) gas obtained by the formula or the reaction of the formula. Purify by distillation.

Si + 2Cl → SiCl ₄ ... Si + 3HCl → SiHCl ₃ + H ₂ ... The boiling point of SiCl4 is 55 ° C., and the boiling point of SiHCl ₃ is 31.8 ° C.

When SiCl ₄ or SiHCl ₃ thus purified to contain several ppm of hydrocarbons is heated together with hydrogen, silicon is deposited by a reaction of the following formula by thermal decomposition and hydrogen reduction.

SiCl ₄ + 2H ₂ → Si + 4HCl …… SiHCl ₃ + H ₂ → Si + 3HCl… At this time, if a silicon rod is put in a reaction furnace and heated to around 1000 ° C by energization, polycrystalline silicon will precipitate around the silicon rod. It is possible to obtain polycrystalline silicon of high purity (the amount of electrically active impurities is 1 ppb or less), which grows and the diameter of the rod is increased.

 FIG. 3 shows a conceptual diagram of this step.

As shown in this figure, metallic silicon and chlorine gas react according to the equation in a fluidized-bed furnace 1 to produce silane trichloride (SiHC).
l ₃ ) is generated. The SiHCl ₃ is led to the distillation column 2 to remove harmful impurities by utilizing the difference in boiling points, thereby producing high-purity SiHCl ₃ . This is mixed with high-purity hydrogen and guided to the reduction reactor 3 to deposit high-purity polycrystalline silicon on the silicon mandrel 5 in the quartz cylinder 4 according to the formula.

<Problems to be Solved by the Invention> However, such a conventional method for producing a pure substance has the following disadvantages.

In this conventional method for producing a high-purity substance, a raw material metal is vaporized as a predetermined compound, and then separated into a desired pure substance and an impurity by a difference in chemical properties (distillation point and the like) of the metal.

Therefore, in this manufacturing method, when the raw material metal cannot be vaporized as a compound, or in the case of a pure substance and an impurity having similar chemical properties, for example, the pure substance and the impurity are transition metals or In the case of rare earth metals, there has been a problem in that they cannot be separated into desired pure substances and impurities.

As a result, there has been a problem that a desired high-purity substance cannot be obtained depending on a raw material metal.

Therefore, an object of the present invention is to provide an apparatus and a method for producing a pure substance capable of improving the purity of various metals whose purification is delayed to the ppb level.

<Means for Solving the Problems> A first invention of the present application is a vaporization means for vaporizing this raw material metal by heating the raw material metal in a non-contact state under ultra-high vacuum, Ionization means for ionizing metal atoms vaporized by the vaporization means, separation means for separating a plurality of metal ions generated by the ionization means by a difference in the ratio of their mass to charge, and ultra-separated metal ions Solidifying means for solidifying under high vacuum;
It is an apparatus for producing a pure substance having:

The second invention of the present application is a vaporization step of vaporizing a raw material metal, an ionization step of ionizing the vaporized metal to generate a plurality of types of metal ions, and accelerating by applying a voltage to the plurality of types of metal ions. The present invention is a method for producing a pure substance, comprising: a separation step of separating these metal ions in accordance with a ratio of mass to charge; and a solidification step of solidifying the separated metal ions.

<Operation> In the pure substance manufacturing apparatus according to the present invention, first, the raw material metal is vaporized by the vaporizing means, and the vaporized metal is ionized by the ionizing means to generate a plurality of types of metal ions. Then, for example, a voltage is applied to these plural types of metal ions by a separation means to accelerate the metal ions, and the metal ions are separated according to the ratio of mass to charge. Next, the separated metal ions are solidified by solidifying means. As a result, a high-purity pure substance (for example, a ppb level high-purity substance) can be produced for all metals.

<Example> Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a conceptual diagram showing a schematic configuration of an apparatus for producing a pure substance according to one embodiment of the invention described in the first claim of the present application.

 In this figure, reference numeral 1 denotes a pure substance manufacturing apparatus.

The pure substance manufacturing apparatus 1 includes a bell jar 2, an ultra-high vacuum pump 3, a plurality of laser beam irradiation devices 4, 4, a laser pulse irradiation device 5, a mass separator 6, a solidifying device 7,
It is composed of

The bell jar 2 is a cylindrical stainless steel vacuum vessel in which a raw material metal 8 is placed. The bell jar 2 has a valve (not shown).
Is attached, and by operating this valve,
Air can be introduced into the bell jar 2 or shut off.

The ultra-high vacuum pump 3 exhausts the air (including hydrogen, helium, etc. in the air) inside the bell jar 2, and reduces the degree of vacuum inside the bell jar 2 to an ultra-high vacuum (10 ^-11 to 10 ^-13 Torr). I do.
As the ultrahigh vacuum pump 3, for example, a cryosorption pump using a Gifford McMahon refrigerator is used. As a result, the inside of the bell jar 2 is reduced in contaminants such as gas elements. Hydrogen and helium are evacuated from the ultra-high vacuum vessel by a cryosorption effect of activated charcoal panel, for example. Gas release from the vacuum vessel wall is prevented by heating and oxidizing the aluminum alloy vacuum vessel in oxygen diluted with argon to form an oxide film on the inner wall. The leak is prevented by a metal seal or the like.

The ultra-high vacuum indicates a vacuum state of 10 ^-8 Torr or less.

The laser beam irradiating device 4 irradiates a laser beam to the material metal (for example, silicon) 8 placed in the bell jar 2 to directly apply heat (heats the material metal 8 in a non-contact state). A plurality of types of metal atoms (silicon and a metal as an impurity contained in the source metal) are vaporized from the source metal 8. As a result, the vaporized plural kinds of metal atoms are not contaminated by the heating device (vaporization device) itself. That is, when the raw material metal is heated via the boat as in the resistance heating type or the like, impurity atoms due to the boat are mixed into the evaporated atoms, but this non-contact heating device 4 can prevent this. Things. Further, a high-frequency induction type heating device can be used.

As the laser beam irradiation device 4, for example, Q-switched Nd / YAG laser, using a N ₂ laser, or the like. In the former, the wavelength λ is 1060 nm and the pulse width is 15 nsec.
m, a laser having a pulse width of 10 to 20 nsec is used. Also,
With this Q-switched Nd / YAG laser, the tube diameter is several microns, 80m
J, its power density is 10 ⁶ to 10 ¹¹ W / cm ² .

As the means for vaporizing the metal atoms of the raw material metal 8, In addition to this electron beam irradiation apparatus using an electron beam of thermal electron emission type also (acceleration voltage 5 kV, a beam current 10 ³ .mu.A), ion beam irradiation device ( an acceleration of ⁶⁹ Ga ions in 1～25KV, the maximum emission current is 10 ² .mu.A; accelerated Ar ⁺ ions by duoplasmatron at 12 kV, emission current may 10 ³ .mu.A) and the like.

The laser pulse irradiation device 5 irradiates a plurality of kinds of vaporized metal atoms with a laser pulse, thereby giving orbital electrons of the vaporized metal atoms energy equal to or more than ionization energy to generate metal ions. The laser pulse irradiation device 5 excites a laser medium by, for example, multiphoton resonance (having a wavelength of 312.3 nm and a pulse width of 6 nm).
nsec), one that excites the laser medium with non-resonance may be used. In the former ionized 100mJ / cm ^2/1 pulse is saturated, but in the ideal case can be selectively ionized.

The mass separator 6 accelerates the metal ions in a semicircular accelerating tube by applying a voltage to the metal ions, and separates a plurality of types of metal ions by double convergence by electric field deflection and magnetic field deflection. Is what you do. The resolution of the mass separator 6 is about M / ΔM = 10000.

The solidifying device 7 selects one of the metal ions thus separated and solidifies it on the substrate.
And an ultra-high vacuum pump 10 and a cryogenic device 11. Specifically, the inside of the bell jar 9 is brought into an ultra-high vacuum state (10 ^-13 Torr) by an ultra-high vacuum pump 10, and the substrate 12 made of a high-purity metal cooled to an extremely low temperature (−253 ° C.) by a cryogenic device 11 is placed on the substrate 12. This is to deposit metal ions.

The temperature of this substrate is extremely low (−253 ° C.), and is set to a temperature that is sufficient to ignore the diffusion of the deposited metal in the solid.

 Hereinafter, a method for producing the substance will be described.

FIG. 2 is a flowchart showing each step of the method for producing a pure substance according to one embodiment of the invention described in the second claim of the present application.

First, the raw metal 8 is placed in the bell jar 2, and the inside of the bell jar 2 is subjected to an ultra-high vacuum (10 ^-13 Tor) by an ultra-high vacuum pump.
r) Set to the state.

Thereafter, heat is applied by irradiating the material metal 8 with laser light of a predetermined wavelength from the laser beam irradiation devices 4, 4 to vaporize the material metal 8 (step S1). As a result,
The vaporized raw metal 8 floats in the bell jar 2 as a plurality of types of metal atoms.

Next, a plurality of types of metal atoms floating in the bell jar 2 are irradiated with laser light having a shorter wavelength than those from the laser pulse irradiation devices 5 to 4 at a higher density. As a result, energy is given to the orbital electrons of the vaporized metal atom, and a plurality of types of metal ions are generated (step S2).

Then, the metal ions are guided to the mass separator 6, and a voltage is applied to the metal ions to accelerate the metal ions in the semicircular acceleration tube 8. Then, metal ions are separated for each type by the double convergence by the electric field deflection and the magnetic field deflection (step S3).

Next, one of the separated metal ions is guided into the bell jar 9 in an ultra-high vacuum state, and the metal ions are deposited (solidified) on the substrate 12 cooled to an extremely low temperature (−253 ° C.) (step S4). .

Since a specific metal element can be separated in this manner, a thin, high-purity pure substance (for example, ppb
Level of high-purity substances).

In addition, as a spillover effect of the production of high-purity metallic substances, the possibility of discovering new physical properties of each metallic substance is improved, and the effect of impurities contained in metallic substances on metallic elements is quantified. Can be

Furthermore, by producing high-purity standard samples,
The analysis and quantification of each metal substance will proceed.

<Effects> As described above, according to the first and second aspects of the present invention, the purity of various metals can be improved to the ppb level.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a schematic configuration of an apparatus for producing a pure substance according to one embodiment of the invention described in the first claim of the present application.
FIG. 3 is a flowchart showing the steps of a method for producing a pure substance according to one embodiment of the invention described in the second claim of the present application, and FIG. 3 is a conceptual diagram showing the steps of producing high-purity polycrystalline silicon. Reference Signs List 1 ... Pure substance manufacturing apparatus, 4 ... Laser beam irradiation apparatus (vaporization means), 5 ... Laser pulse irradiation apparatus (ionization means), 6 ... Mass separator (separation means), 7 ... Solidification apparatus (solidification) means).

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shin Tsuchiya 1-297 Kitabukuro-cho, Omiya-shi, Saitama Mitsui Kinzoku Co., Ltd. Central Research Laboratory (56) References JP-A-61-48416 (JP, A)

Claims (2)

(57) [Claims] 1. A vaporizing means for vaporizing a raw metal by heating the raw metal in a non-contact state under ultra-high vacuum, and an ionizing means for ionizing metal atoms vaporized by the vaporizing means. Means, separation means for separating a plurality of metal ions generated by the ionization means by a difference in the ratio of their mass to charge, and solidification means for solidifying the separated metal ions under ultra-high vacuum. An apparatus for producing a pure substance, comprising: 2. A vaporizing step of vaporizing a raw material metal, an ionizing step of ionizing the vaporized metal to generate a plurality of types of metal ions, and applying a voltage to the plurality of types of metal ions to accelerate them. A method for producing a pure substance, comprising: a separation step of separating these metal ions according to a ratio of mass to charge; and a solidification step of solidifying the separated metal ions.