Tetrafluorosilane production process, method for assaying impurities in tetrafluorosilane, and gas based thereon

FIELD: silicon compounds technology.

SUBSTANCE: tetrafluorosilane production process comprises following stages: (1) hexafluorosilicate heating; (2-1) reaction of tetrafluorosilane gas containing hexafluorodisiloxane formed in stage (1) with fluorine gas; (2-2) reaction of tetrafluorosilane gas containing hexafluorodisiloxane formed in stage (1) with fluorine-polyvalent metal compound; (2-3) reaction of tetrafluorosilane gas obtained in stage (2-1) with fluorine-polyvalent metal compound. Finally, high-purity tetrafluorosilane with 0.1 ppm by volume of hexafluorodisiloxane is obtained, which is applicable in manufacture of optical fiber, semiconductors, and sun battery elements.

EFFECT: reduced content of impurities in product.

24 cl, 1 dwg, 1 tbl, 9 ex

 

The technical field to which the invention relates.

The present invention relates to a method of obtaining tetrafluorosilane, the method of analysis of the content of impurities in tetrafluorosilane high purity and its application.

Describe the level of technology

Tetrafluorosilane (hereinafter sometimes referred to as "SiF4is used, for example, as a raw material for optical fibers, semiconductors or solar cells, as well as to obtain the desired high purity product. As for the method of its production, it is known, for example, a method of obtaining SiF4the reaction of SiO2with HF in the presence of concentrated sulfuric acid (Japanese Unexamined Patent Publication No. 57-135711 (JP-A-57-135711)).

However, the problem with this method is the formation of water as a by-product during the reaction between the source SiO2and HF. The resulting water can be removed using concentrated sulfuric acid, however, such removal is incomplete, and the resulting SiF4contains significant amounts of HF and hexaphenyldisilane ((SiF3)2O)obtained by the reaction of water with SiF4and, in addition, contains carbon dioxide, which is difficult to distinguish from SiF4which formation is associated with a small number of derived carbon in concentrated sulfuric acid is the same.

In addition, a method of obtaining SiF4thermal decomposition fluorosilicate preparation. However, the fluorosilicate preparation contains H2On or impurities such as derivatives of silicic acid containing trace amounts of oxygen (for example, SiO2), even if satisfactory pre-treatment such admixture may react with SiF4with the formation of hexaphenyldisilane in the implementation of thermal decomposition.

Also known purification method SiF4containing (SiF3)2O CO2or HF. In the case when SiF4contains such gaseous impurities (SiF3)2O CO2and O2and is intended for use, for example, as raw material for the production of thin silicon films, the oxygen impurity adversely affects the properties of semiconductor or fiber. In accordance with the above, the required SiF4with low impurities content, and equally necessary method of analysis of trace amounts of impurities.

As for the method of cleaning SiF4in Japanese Unexamined Patent Publication No. 57-156317 (JP-A-57-156317) describes a method of purification of SiF4containing (SiF3)2About as a result of its contact with the adsorbent. However, after regeneration and further use of the adsorbent is not always restored it to recognize the Nai absorption capacity. The reason for this phenomenon is not clear, however, is that it is associated with the decomposition of hexaphenyldisilane in the pores of the adsorbent. The addition of SiO2formed during the decomposition, to the centers of adsorption lose the ability of the adsorbent to regenerate and reuse that creates a problem associated with the processing of the adsorbent, as waste production. In addition, if insufficient annealing of the adsorbent before passing gas flows adverse reaction of water with the formation of hexaphenyldisilane.

Description of the invention

The present invention was made to eliminate the above drawbacks and consisted in the development of the method of obtaining tetrafluorosilane, the method of analysis of impurities in tetrafluorosilane high purity and its application.

As a result of extensive investigations directed to solving the above problems, the authors of the present invention have found that such problems can be solved using the method of receiving tetrafluorosilane, including the state (1) heating fluorosilicate preparation, stage (2-1) reaction of gaseous tetrafluorosilane containing exaptations formed in stage (1) with gaseous fluorine, stage (2-2) reaction of gaseous tetrafluorosilane containing exaptations formed n the stage (1) with fluoride polyvalent metal, or stage (2-1) reaction of gaseous tetrafluorosilane containing exaptations obtained in stage (1), with gaseous fluorine, and the stage (2-3) reaction of gaseous tetrafluorosilane formed on the stage (2-1) with fluoride polyvalent metal.

In addition, the inventors found that the above problems can be solved using the method of analyzing impurities in tetrafluorosilane high purity, resulting in the conversion of tetrafluorosilane containing as impurities gaseous N2, gaseous O2, gaseous N2, gaseous, gaseous CH4and/or gaseous CO2in contact with the adsorbent order to separate the impurities from tetrafluorosilane and their introduction together with the carrier gas into the gas chromatograph for analysis.

The present invention was created based on the specified method.

The present invention provides a method of obtaining tetrafluorosilane, including the state (1) heating fluorosilicate preparation, stage (2-1) reaction of gaseous tetrafluorosilane containing exaptations formed in stage (1), with gaseous fluorine, stage (2-2) reaction of gaseous tetrafluorosilane containing exaptations formed in stage (1), with fluoride polyvalent metal, or stage (2-1) reaction g is sobrannogo of tetrafluorosilane, containing exaptations obtained in stage (1), with gaseous fluorine, and the stage (2-3) reaction of gaseous tetrafluorosilane formed on the stage (2-1), Florida polyvalent metal.

The present invention also provides a method of analyzing impurities in tetrafluorosilane high purity, which consists in contacting the gaseous tetrafluorosilane containing gaseous N2, gaseous CO2, gaseous N2, gaseous, gaseous CH4and/or CO2with adsorbent order to separate the impurities from tetrafluorosilane and the introduction of impurities together with the carrier gas into the gas chromatograph for analysis of impurities.

In addition, the present invention also provides a method of analyzing impurities in tetrafluorosilane high purity, which consists in the introduction of gaseous tetrafluorosilane containing exaptations, as an impurity, in an optical cell with a window made of metal halide and analysis on exaptations and/or hydrogen fluoride by the method of IR-spectrometry.

In addition, the present invention provides for gas for the production of optical fibers, containing tetrafluorosilane obtained as described above.

The present invention also provides gas for semiconductors containing gaseous tetrafluorosilane, received as described above.

In addition, the present invention provides for gas for the production of solar battery element containing tetrafluorosilane obtained as described above.

Brief description of drawings

The drawing depicts a schematic view of the apparatus used for the method of obtaining tetrafluorosilane according to the present invention.

In the drawing 1 denotes a reactor thermal decomposition, 2 - tube for the reaction of decomposition, 3 denotes electric oven, 4 - heater, 5 - fluorosilicate preparation, 6 - thermometer, 7 - fixing plate of porous Ni, 8 denotes a reactor for the production of F2(filled with fluoride polyvalent metal, or without him), 9 - reactor (silicone), 11 - membrane module for gas separation, 12, 36 - vacuum pumps, 13, 14, 21 - gauge, 15 - bypass with the separation membrane, 16 denotes a tank for regeneration, 19 absorption column, 22-25 - valves to adjust the flow rate, the 26 - pressure regulator, 27-32 - gates for sampling and 33-35 - gates for the regeneration tank.

Description of the preferred implementation

Below is a detailed description of the present invention. The fluorosilicate preparation is one of the preferred compounds, selected from the group consisting of the fluorosilicate preparation of alkali metal fluorosilicate preparation of alkaline-earth metal. Examples of such compounds can serve as Li2SiF6, Na2SiF6, K2SiF6Cs2SiF6, MgSiF6, CaSiF6, SrSiF6and BaSiF6. All of these compounds are inexpensive and available industrial products, and in the method of the present invention, these substances can be used individually or as mixtures of two or more of the listed compounds. Most preferred of these substances, due to its low cost and mass production, is Na2SiF6(sodium fluorosilicate preparation), which is produced as a by-product in the production process of phosphoric acid.

In the case of Na2SiF6(sodium fluorosilicate preparation)generated in the production process of phosphoric acid, Na2SiF6is a crystalline powder with a particle size from tens to hundreds of μm, sometimes containing 10% wt. water. Accordingly, in the method of the present invention, which is intended to receive tetrafluorosilane using fluorosilicate preparation as an initial matter, the latter is preferable to grind and dry before carrying out stage (1). As a result of crushing fluorosilicate preparation surface area of crystals is increased, and this contributes to the drying of the crystal is s.

Grinding crystalline fluorosilicate preparation can be carried out using devices such as ball mill, and the crushed crystals up to 100 μm or less, preferably 10 μm or less, more preferably 1 μm or less. Then the crystals are dried by passing nitrogen, air, etc. the Temperature of the beginning of decomposition may vary depending on the nature of the fluorosilicate preparation, and therefore, the drying temperature selected from a temperature range below the temperature of the beginning of decomposition. For example, in the case of drying of sodium fluorosilicate preparation preferred drying temperature of the crystals is between 200°With up to 400°more preferably, from 300°With up to 400°C.

The purpose of the stage drying after grinding of the crystals is to reduce the number of such impurities as HF and (SiF3)2O, formed as by-products in the reaction SiF4obtained in stage (1), with water. For example, in the case of sodium salt as fluorosilicate preparation SiF4is formed by the following reactions (1)and it is assumed that in the presence of HF and water (SiF3)2O are formed according to reaction (2):

In the method of obtaining tetrafluorosilane coz the ACLs present invention in the presence of HF and (SiF 3)2O SiF4when conducting stage (1) these substances may be processed at the next stage, and don't pose any problems, however as a result of grinding and drying the crystalline fluorosilicate preparation to stage (1) quantity produced (SiF3)2O can be reduced to 1/3-1/5. The reason education (SiF3)2O cannot be excluded completely, is that the crystals remain trace amounts of water and oxygen-containing derivatives of silicic acid (for example, SiO2). Reducing the number of generated amount (SiF3)2O is advantageous also in terms of profitability of the process, because in this case can be reduced the number of fluorine gas (hereinafter sometimes use the symbol "F2")added, for example, at the stage (2). In addition, crystalline fluorosilicate preparation is preferably dried at a temperature of 50-200°that facilitates subsequent grinding of the crystals.

In the method of obtaining tetrafluorosilane according to the present invention, the respective operations of drying and grinding fluorosilicate preparation and drying the crushed crystals preferably are carried out before stage (1), however, when using the fluorosilicate preparation with low water content, these instruments do not wire the tsya. However, complete removal of water contained in the crystals fluorosilicate preparation, is a very difficult operation, and drying temperature has an upper limit, above which the problems associated with the formation of SiF4. Therefore, it is difficult to completely prevent the formation of HF and (SiF3)2O that is associated with the presence of water crystals. Moreover, oxygen-containing derivative of silicic acid (for example, SiO2cannot be removed as a result of heat treatment, and its presence leads to the formation of (SiF3)2O.

Stage (1) represents the heat fluorosilicate preparation with the formation of SiF4. Stage (1) can be performed in a stream of inert gas, such as nitrogen gas, or in vacuum. The preferred temperature range of heating can be selected in accordance with the nature of the used fluorosilicate preparation. For example, in the case of using barium salt is heated, preferably, carried out at a temperature in the range of 400-700°and in the case of sodium salt of heating is carried out at a temperature in the range of 500-800°C.

In the method of obtaining tetrafluorosilane according to the present invention stage (2-1), stage (2-2) or stage (2-1) and (2-3) is carried out after carrying out stage (1). Stage (2-1) represents the Tadeu reaction between the mixed gas, containing SiF4and (SiF3)2O, obtained in stage (1), with gaseous fluorine. The preferred reaction temperature is set in the range of 100-350°S, more preferably 200-350°C. Gaseous F2is reacted in an amount of from 1 to 2 moles per mol (SiF3)2O contained in the received SiF4. It is assumed that the reaction in stage (2) proceeds according to the following equation (3), according to which (SiF3)2O can turn into SiF4and O2:

If the molar quantity of gaseous F22 times the amount of the formed (SiF3)2O, there is the effect of saturation, which is undesirable in terms of the profitability of the process. Taking into account the corrosion resistance of the material of construction of the reactor to the effects of gaseous F2a preferred reaction temperature is 350°With or below.

Stage (2-2) represents the reaction of gaseous SiF4containing (SiF3)2O, formed in stage (1), with fluoride polyvalent metal. Stage (2-3) represents the reaction of gaseous SiF4obtained in stage (2-1), with fluoride polyvalent metal. The reaction occurring at the stage (2-2) or (2-3), is a decomposition exaptation the Ana under the action of fluoride polyvalent metal with the formation of SiF 4and O2.

Examples of fluorides polyvalent metals, which can be used on stage (2-2) or (2-3), are CoF3, MFN3, MFN4, AgF2, CeF4, PbF4and K3NiF7. These compounds are able to activate the fluorine when heated, and under the action of activated fluorine can occur decomposition of hexaphenyldisilane flowing on anticipated reactions, equations predstavlennym(4)-(10):

The above fluorides polyvalent metals may be used individually or as a mixture.

The following describes a method of producing fluoride polyvalent metal in the case, when the fluoride polyvalent metal is a CoF3on the media. So, for example, With(NO3)2·6N2O is dissolved in water, the resulting aqueous solution to absorb dry Al2About3(NST-3, produced by Nikki Called K.K.), and the resulting material is dried in a warm bath to remove water. After drying, the alumina fill the Nickel tube and carry out the calcination in a stream of N2with a the Yu remove residual quantities of water and nitric acid, obtaining oxide. After that, the transmission 10% F2(diluted N2), carry out the fluorination With and alumina, used as a carrier.

In the case of oxides of aluminum, titanium, zirconium, etc. as forming tools, the oxygen on the surface of the carrier and SiF4react with each other to form hexaphenyldisilane, resulting in the need to carry out a thorough fluoridation before passing SiF4. Fluoridation media is easily accomplished as the result of passing the heated gaseous fluorine or HF. In the final processing of gaseous fluorine before use can be obtained of the target fluoride polyvalent metal.

Stage (2-2) or (2-3) is preferably carried out at a temperature of 50-350°more preferably, at 150-350°C. by passing heated fluoride polyvalent metal through the mixed gas consisting of hexaphenyldisilane and SiF4, the decomposition of hexaphenyldisilane with the formation of SiF4and O2. In the case when the linear velocity is too high, the area of leakage (break-through zone and extends the lifetime decreases, resulting in a transmission, preferably, carried out with a linear speed of 10 m/min or less at ordinary temperature and atmospheres of the second pressure.

If we continue the reaction at the stage (2-2) or (2-3), fluoride of the metal in a higher valence state turns into a fluoride of the metal to the usual valence and loses the ability to fluoridation, at the output of the reactor is detected exaptations. In this case, it is possible to stop the reaction and to re fluoridation lower fluoride gazoobraznym fluoride with the formation of a fluoride of a metal of higher valency, however, in order to implement a continuous mode of reaction is also possible to use two or more reaction columns, thereby continuously performing the decomposition reaction as a result of repeated cycles of reaction and regeneration. The timing of switching from one mode to another can be confirmed by data analysis on the content of hexaphenyldisilane at the reactor exit, pursued by the method of IR-spectrometry with Fourier-transform (FT-IR).

Stage (2-2) or (2-3) is preferably carried out in the presence of fluorine gas, and passing the heated gaseous fluorine, the reaction may proceed in a continuous mode during regeneration of fluoride polyvalent metal in accordance with the following equations(11)-(17):

Tetrafluorosilane containing exaptations as an impurity, is mixed with gaseous fluorine in equimolar amounts relative to hexaphenyldisilane and passed through fluoride polyvalent metal, resulting simultaneously flow through the reaction of the decomposition of hexaphenyldisilane under the influence of fluoride polyvalent metal and regeneration of the metal fluoride with normal valency under the influence of fluorine gas. In this case, the volumetric rate is 10000 h-1or less, preferably 5000 h-1or less, more preferably 1000 h-1at ambient temperature and atmospheric pressure. The quantity of fluorine gas can be controlled by applying an equimolar amount of gaseous fluorine in the analysis of the content of hexaphenyldisilane at the entrance to the reactor by the method of FT-IR.

Gaseous tetrafluorosilane obtained in stages (2-1), (2-2) or stages (2-1) and (2-3), sometimes contain excessive amounts of fluorine gas. In accordance with the method of obtaining tetrafluorosilane according to the present invention, stage (3) contacting silicon with gaseous tetrafluorosilane containing gaseous fluorine, preferably carried out after stage (2-1), the hundred and the AI (2-2) or the steps (2-1) and (2-3).

Stage (3), which carry out the conversion of excess gaseous fluorine in SiF4preferably carried out at a temperature of 50°s or higher, more preferably at 100°With or higher, and even more preferably at 150°C or higher. Used in stage (3) silicon, preferably is a silicon surface hydroxyl group which is subjected to heat treatment using inert gas such as nitrogen, at a temperature of 400° (C or above, preferably at 400-600°C.

At stage (3) it is undesirable to use SiO2instead of silicon, because the reaction with HF contained in the SiF4formed N2And (SiF3)2O, in accordance with the following schemes of reactions (18) and (19):

Gaseous F2reacts with the silicon surface, and therefore, despite the fact that the particle size of silicon and its surface area has no special limitation, the chip size of particles of the order of several mm is preferred with regard to gas permeability, contact characteristics or operations for filling. Preferred silicon chip has a purity of 99.9 wt.%. or higher, more preferably, 99,999% wt. or higher, and most preferably corresponds to the grade of the semiconductor is a silicon o cards.

The method of receiving tetrafluorosilane according to the present invention preferably includes a step (4) shielding gas obtained in stage (2-1), (2-2), stages (2-1) and (2-3), stages (2-1) and (3), stages (2-2) and (3) or stages (2-1), (2-3) and (3)the gas separation membrane and/or carbon molecular sieves.

The gas separation membrane, preferably, is a SiO2-ZrO2ceramic membrane and/or poly(4-methylpentene-1)heterogenizing membrane. Carbon molecular sieve (molecular sieve carbon)preferably has a pore size of about 5Å or less.

SiF4obtained by the method of the present invention may contain impurities, formed on the respective described above stages. Examples of impurities can serve (SiF3)2O, H2O2N3and HF. In addition, may contain impurities such as CO and CO2, the formation of which is associated with a small amount of carbon present in the original fluorosilicate preparation. To obtain SiF4high purity such impurities should preferably be separated by treatment.

According to the method of obtaining tetrafluorosilane of the present invention, SiF4containing, for example, impurities such as O2N3, CO, CO2and HF, is brought into contact with the gas-separating member the Noi and/or carbon molecular sieve for the separation of O 2N2, CO, CO2, HF, etc. from SiF4in the result that can be obtained SiF4high purity.

Examples of gas separation membranes include gas-separating membrane module SiO2-ZrO2(module size: F50×300L), manufactured by Kyocera Corporation, and poly(4-methylpentene-1) heterogenizing membrane (module size: f×500L), manufactured by Dai-Nippon Ink&Chemicals, Inc. Such separation membrane can be used individually or in combination.

Gas separation membranes intended for use in the method of obtaining tetrafluorosilane according to the present invention is not limited to the above separation membranes, provided that the separation membrane has a large coefficient of permeability (separation) SiF4and such impurities as2N2, CO, CO2and HF.

Carbon molecular sieves are not limited to the above example, assuming that the carbon molecular sieve has a sufficiently large pore size for the adsorption of these impurities like O2N2, CO, CO2and HF and a sufficiently small pore size for absorption SiF4. The pore size is preferably 5Å or less, because these pores absorb O2N2, CO, CO2and HF and does not adsorb SiF4.

Below opisyvaet the method of purification of gaseous SiF 4using the gas separation membrane module.

According to the method of purification of gaseous SiF4using the gas separation membrane module, this module first blow N2or similar gas to remove H2O, which reacts with SiF4. Purging is considered complete when the supply of gaseous N2dew point with permeable and impermeable side of the membrane reaches the same value. N2is not required by the gas used for cleaning, provided that the dew point is -70°s or less.

The supply side of the dried gas separation membrane module is in contact with SiF4containing impurities such as O2N2, CO, CO2and HF, and has a selective permeability for these impurities, while SiF4concentrated with impermeable side, which may be obtained SiF4high purity. Concentrated with impermeable side SiF4can optionally be brought into contact with carbon molecular sieve.

According to the method of separation of SiF4O2N2, CO, CO2, HF, etc. using the gas separation membrane module, with a significant difference between the permeable side and impermeable side, high-purity SiF 4can be obtained with impermeable side of the membrane, in connection with impermeable side (inlet side) of the membrane is supported by a pressure equal to atmospheric or higher pressure. In addition, if desired, the pressure on the permeable side of the membrane may be reduced to atmospheric pressure or lower pressure.

The following describes a method of purification of gaseous SiF4using a carbon molecular sieve.

The example used carbon molecular sieve (hereinafter sometimes abbreviated to "MSC") can serve as MORSIEBON 4A (trade mark)manufactured by Takeda Chemical Industries, Ltd. According to the cleaning method using MSC adsorbent is loaded into the vessel and then subjected to heat treatment in an environment inert gas such as N2at a temperature of 100-350°in order to remove water, CO2and other adsorbed impurities. The heat treatment may be carried out in the purification of N2in a vacuum. Heat treatment is considered complete when the input and exhaust gases reach the same dew point. N2not a necessary gas for drying, and may use a different gas, provided that the dew point is -70°s or less.

As a result of contact with MCS SiF4containing impurities such as O N2, CO, CO2and HF formed during the process of the present invention, and providing the absorbance at MSC only these impurities can be obtained SiF4high purity.

Adsorption on MSC gas impurities such as O2N2, CO, CO2and HF contained in the SiF4preferably carried out in accordance with the General method of purification adsorption separation, supporting the adsorption low temperature and high pressure. In the case of adsorption at ordinary temperatures, the pressure support is equal to atmospheric or higher, preferably 0.5 MPa or higher, more preferably 1 MPa or higher. In the case of absorption of gaseous impurities upon cooling, the preferred pressure is set below the pressure liquefaction SiF4.

The linear velocity (LV, m/min) at atmospheric pressure is 5 or less, preferably 2 or less, more preferably 1 or less. Space velocity (SV, H-1) is 1000 or less, preferably 500 or less, more preferably 200 or less.

When using two absorption columns SiF4can be subjected to continuous treatment in the alternate implementation of the adsorption and regeneration. Regeneration can be accomplished by pumping in vacuum parts heated SiF4located in the column and the sorption, and its submission to the column regenerative desorption, by blowing in the direction opposite the absorption cleanup.

The method of receiving tetrafluorosilane according to the present invention is also characterized by using the following analytical method designed to control the process.

Tetrafluorosilane obtained by the method of the present invention may be a product of high purity containing hexaphenyldisilane as an impurity in the number 1 ABC/m or less. Can also be obtained tetrafluorosilane high purity containing hexaphenyldisilane 0,1 ABC/m or less.

The following describes the method of analysis of impurities in high-purity tetrafluorosilane of the present invention. With regard to the following numerical values, it is assumed that they do not have specific limitations.

According to the present invention, a method of analyzing impurities in high-purity tetrafluorosilane characterized by the fact that carry out the contacting of tetrafluorosilane containing as impurities gaseous N2, gaseous O2, gaseous N2, gaseous, gaseous CH4and/or gaseous CO2with the adsorbent, with the aim of separating impurities from tetrafluorosilane and their introduction together with the carrier gas in a gas of chromium is ograph for analysis.

Components that can be analyzed by the method of the present invention, are trace amounts of H2About2N2, CO, CH4and/or CO2. Also can be analyzed components, such as F2, HF and (SiF3)2O.

As the adsorbent, it is preferable to use activated carbon, spherical activated angle on the basis of oil pitch and/or carbon molecular sieve with a pore size of about 6Å or more.

According to the method of the present invention, predalone (SUS column with an inner diameter f of 3 mm and a length of 1 m)filled SHINCARBON-S (activated carbon adsorbent manufactured by Shimadzu Corporation) with a particle size of 60-100 mesh, fixed in a bath with a constant temperature and maintained at 100°C. In such predalone through the gas valve injected 1 ml of SiF4containing impurities such as H2About2N2, CO, CH4, CO2, HF and (SiF3)2O. as a carrier gas can be used helium (Not) high purity.

In the sample, Not portable high purity through predalone, there is a separation of H2, CO2N2, CO, CH4and CO2and adsorption SiF4, HF and (SiF3)2O. Such gases as H2O2N2, CO and CH4can be separated using the least is sustained fashion column, for example, with molecular sieve 5A (trade name). In the presence of CO2the mixture may be separated using a separation column with POLAPACK Q (trademark).

After that, the separated components are injected into the PDD (pulsed discharge detector) and measure their concentration. The limit of detection of such gaseous impurities, as H2O2N2, CO, CH4and CO2that is 0.01 OBC/million According to the method of the present invention, the quantitative analysis can be carried out in the concentration range 0,05-0,01 OBC/million that allows you to analyze SiF4high purity.

Use in the method of analysis of the present invention predalone with the above-mentioned activated carbon due to the fact that its ability to divide the sample into a group of components, including N2O2N2, CO, CH4and CO2and the group, consisting of a main component, SiF4and impurities, HF and (SiF3)2O significantly superior to other adsorbents such as silica gel, zeolite and porous polymer granules. It is preferable to use activated carbon-based petroleum pitch, as in this case, the ash content (such as2CO3very little compared to conventional activated carbon, and can be achieved with good separation based the aqueous component of SiF 4. Even more preferred adsorbent is a molecular sieve carbon, which can be achieved excellent separation of the main component, SiF4compared to the speakers and YOU. The reason for this, apparently, is good control of pore size and their distribution.

On the other hand, adsorbed in predalone HF (SiF3)2O and SiF4can stand out and be regenerated using the system backwashing, which, with the help of a crane, changes the direction of flow of carrier gas of low purity, and predalone is blown in a direction opposite to the input of the sample. The temperature of the furnace, which is predalone may be increased from 100 to 200°simultaneously with the switching valve, which facilitates desorption of HF (SiF3)2O and SiF4. Temperature aging predalone and separation column can have a value commonly used maximum temperature plus 50°C.

In accordance with the present invention a method for the analysis of impurities in tetrafluorosilane high purity consists in the introduction of tetrafluorosilane containing exaptations as an impurity, in the optical cell, the window which is made of a metal halide, and analysis of hexaphenyldisilane and/or hydrogen fluoride methodology is infrared spectrometry.

In the method using infrared spectrometry in the analysis of the present invention can be measured concentrations hexaphenyldisilane contained in tetrafluorosilane, and the concentration of hydrogen fluoride (HF).

In the analysis (SiF3)2O, due to the difficulty of obtaining a gaseous standard content (SiF3)2O can be determined, for example, from the ratio of optical densities {(SiF3)2O/SiF4} for the characteristic IR absorption (SiF3)2O at 838 cm-1and the characteristic IR absorption SiF4at 2054 cm-1. In this case, known in the technical literature characteristics (e.g., Anal. Chem., 57, 104-109 (1985)), can be used as a standard for optical density (SiF3)2O.

SiF4containing (SiF3)2O, is introduced into the gas cell with a large optical path, for example, of the order of 4 m or more and using the method of IR-spectrometry, determine the content (SiF3)2O SiF4in the amount of up to 0.1 ppm or less. As an infrared spectrometer is preferable to use a spectrometer with Fourier transformation.

Analysis method according to the present invention allows to determine low concentrations (SiF3)2O by the absorption in the infrared region of the spectrum is ri wavelength 838 cm -1that characteristic (SiF3)2O.

In addition, the concentration (SiF3)2O SiF4can be measured by indirect method by adding a constant, excess F2to a constant number of SiF4containing (SiF3)2O, the reaction between (SiF3)2O and F2when heated to 300°and determining the flow rate of fluorine.

In the method of analysis according to the present invention dimension, preferably, carried out by the method of FT-IR, while at least part of the line for sampling in contact with SiF4made of stainless steel or electropolished stainless steel, and structural material of the window of the gas cell for optical transmittance represents KCI, AgCI, KBr or CaF2. Similarly (SiF3)2O, HF can be analyzed with a concentration of 0.1 ppm or less on the spectrum of the IR absorption of the optical density at a wavelength of 4040 cm-1, characteristic of HF.

The following describes the use of high-purity tetrafluorosilane obtained by the method of the present invention.

With increasing the degree of integration of transistors, resulting in the improvement of semiconductor devices, made possible a significant increase in the integral of the density or the switching rate of the individual is selected transistors. However, the delay spread associated with the quality of the wiring, negates the increase in the operating speed of the transistor. The latency associated with electrical wiring, it becomes a particularly serious problem when the line widening to 0.25 μm and more. To solve this problem, the aluminum wiring replace copper wiring with low resistance and is used nuscodebetting the interlayer insulating film in order to reduce the capacitance between the wires. Example discoverycanada material for a line width of 0.25 to 0.18 or 0,13 μm can serve as SiOF (oxide film doped with fluorine, ε: about 3.5)obtained by CVD method in a HDP (high density) plasma. As currently continues to develop new ways of using SiOF for the interlayer insulating film and aluminium alloys for electrical, high-purity SiF4the present invention may find application as operauser material.

Glass for optical fibers includes an inner portion and a covered portion. The inner part should have a higher refractive index than the peripheral covered part, so as to facilitate the passage of light in the Central part. The increase of the refractive index can be achieved by introducing alloying additives such as Ge, AI, Ti, etc. is, however, one should take into account the side effect of increasing light scattering on additives, resulting in a decrease in the efficiency of light transmission. Adding fluorine in the coating, the refractive index can be reduced to values lower than the refractive index of pure quartz, and, as a consequence, pure quartz or quartz with a low content of alloying elements can be used in the Central part with the aim of improving the efficiency of light transmission. Fluorine in the atmosphere is Not added during the heat treatment of fine-grained glass material (SiO2) in the atmosphere SiF4and, thus, high-purity SiF4the present invention can be used as the gas used for receiving optical fibers.

The present invention is additionally illustrated by the following examples without limiting the scope of the invention.

Example 1.

The fluorosilicate preparation of sodium (Na2SiF6) 5 with an average particle size of about 70 μm, purity 89% wt. or more (water content: 10% by weight. or less), obtained as a by-product in the production process of phosphoric acid, dried with hot air at 120°and 1500 g of the obtained material was loaded in the Central part of the tube 2 for the reaction of decomposition (inner diameter: 90 mm, length: 1500 mm construction material: Nickel) in the reactor 1 thermal decomposition of p is shown in the drawing, and both ends of the tube closed by a plate 7 made of porous Ni. Then, while maintaining the temperature Na2SiF6below 400°using the electric furnace 3 (length: 1000 mm), opening the valve 22, missed gaseous N2(dew point: -70°s or less) at a rate of 1000 ml/min, and after confirming that the concentration of HF in the exhaust gas is decreased to 1 ppm or less, drying Na2SiF6completed.

After that, the flow rate of N2was set equal to 200 ml/min and the temperature of the electric furnace 3 was increased to 700°C and maintained at this value. Which resulted in formation of SiF4with a concentration of about 30%. The samples of gas were taken by a valve 27 and defined the concentration of gaseous impurities. The results obtained are presented in Table 1. From the presented results one can see that the product contains 8560 ppm (SiF3)2O.

Example 2

Gaseous SiF4received according to the method described in example 1, except that the dry crystals of sodium fluorosilicate preparation used in Example 1 was used with the grinder, and the resulting powder with a particle size of about 1 μm filled tube 2 for the reaction of decomposition. Samples of gas formed was collected by a valve 27 and defined the concentration of gaseous impurities. The results pre is presented in Table 1. The results imply that the grinding leads to decreasing concentrations (SiF3)2O.

Example 3

Gaseous SiF4obtained in Example 2 was introduced into the reactor 8 for processing F2(the structural material of the reactor tube: Nickel, inner diameter: 8 mm, length: 1000 mm), shown in the drawing, through the valve 23 was injected 3 ml of 100% gaseous fluorine, and at 300°proceeded reaction between (SiF3)2O contained in the SiF4and F2. The sample gas formed was collected through the valve 28 and analyzed. The results obtained are presented in Table 1. From the obtained results we can see that the concentration (SiF3)2O is reduced to values less than 0.1 OBC/million

Example 4

In the reaction tube (construction material: Nickel) reactor 9, shown in the drawing, downloaded 60 ml of silicon chips size 8-10 mesh, which were treated for 3 hours at 500°S, skipping N2(dew point: -70°s or less) at a rate of 300 ml/min and Then the temperature of the reaction tube filled with silicon chips, was set equal to 150°and introducing the gas obtained in Example 3, with a view to its reaction with excess F2and silicon. Samples of gas formed was collected through the valve 29 and analyzed. The results are presented in the Table is 1. From the presented data shows that the concentration of fluorine gas reduced to values less than 0.1 OBC/million

Example 5

Through the gas separation membrane module 11 (SiO2-ZrO2the membrane is manufactured by Kyocera Corporation), shown in the drawing, with the rate of 2-3 l/min was passed N2(dew point: -70°s or less) and have it drying to achieve the same dew point at the inlet and outlet of the module. Feeder side in a dry gas-separating membrane module 11, at atmospheric pressure, is injected with a gas obtained in Example 4, and the discharge-pressure gas-permeable side using a vacuum pump 11 such gaseous impurities as the N2separated from the permeable side. Samples of the gas permeable side were taken through the valve 30 and the gas impervious side of the membrane were taken through the valve 31. The obtained samples were analyzed. The results of the analysis are presented in Table 1. From the obtained results we can see that a large part of the gaseous impurities may be removed from the permeable side of the membrane.

SiF4with impermeable side of the membrane froze in the regeneration tank 16, cooled to a temperature of -120°using liquid N2through valves 24 and 33 and adjusting the pressure.

Example 6

In the absorption column 19 (inner diameter: 16 mm, length: 1000mm), shown in the drawing, downloaded 100 ml MSC (MORSIEBON 4A, produced by Takeda Chemical Industries, Ltd.) and the system was dried by skipping N2(dew point: -70°s or less) at 500°With a speed of 300 ml/min to achieve the same dew point at the inlet and outlet of the system. After cooling and purging is Not SiF4recovered in the recovery tank 16 in Example 5 were transferred into the gaseous state at ordinary temperature and introduced into the absorption column 19. During this operation, set the pressure of 0.9 MPa and space velocity of the gaseous SiF4was set equal to 350 ml/min using a valve 25 for regulating the flow rate, pressure regulator 26 and the pressure gauge 21. The gas discharged from the absorption column 19, were analyzed for the presence of gaseous impurities, using the above method; the results are presented in Table 1. From the presented results one can see that the measured concentrations of all impurities was less than 0.1 OBC/million

Example 7

The gas obtained in Example 4, froze in the regeneration tank 16, cooled to -120°With the help of liquid nitrogen, through the valves 24 and 33, by adjusting the pressure using the bypass line 15 of the dividing membrane, shown in the drawing. Then, as a result of gas at ordinary temperature, SiF4collected in generationem tank 16, introduced into the absorption column 19, carrying out processing in the same manner and under the same conditions as described in Example 6. The gas inlet of the absorption column 19 and the gas exhaust from the absorption column 19, analyzed the obtained results are presented in Table 1. The results show that the measured concentrations of all impurities at the outlet of the reactor was less than 0.1 OBC/million

Example 8

Preparation of fluoride polyvalent metal, deposited on a substrate: 10% CoF3/Al2About3

In 200 ml of water was dissolved 26,4 g (0,0091 mol) of Co(NO3)2·6N2O [qualification: high purity reagent]. The resulting aqueous solution was absorbed on of 100.2 g of dry Al2About3(NST-3, produced by Nikki Called K.K.) and the resulting material was dried in a warm bath to zero water content. After drying, the alumina was loaded in the reaction tube (construction material: Nickel) reactor 8, shown in the drawing, and progulivali for 12 hours at 400 C in a current of N3(400 ml/min), resulting in the deleted residual amounts of water and nitric acid to obtain oxide. Then, 250°With, at the rate of 1,000 ml/min, missed 10% gaseous F2(thinning (N2for performing the fluorination of alumina and From. The fluorination was carried out before the same concentration of fluoride in I the de and at the exit of the reactor. Fluoride concentration was measured by passing a gas to be analyzed through a 5% aqueous KI solution and titration of the liberated iodine 0,1N aqueous solution of Na2S2O3.

Using 100 ml of the above fluoride polyvalent metal, carried out the decomposition of hexaphenyldisilane. Gaseous SiF4obtained in Example 2 was introduced into the reactor 8 (structural material of the reaction tube: Nickel, inner diameter: 8 mm, length: 1000 mm), shown in the drawing, and (SiF3)2O contained in the SiF4, reacts with fluoride polyvalent metal (CoF3) at 200°C. the Samples generated gas was collected through the valve 28 and analyzed. The results obtained are presented in Table 1. From the presented results one can see that the number (SiF3)2O reduced to values less than 0.1 OBC/million Analysis at the outlet of the reactor was continued and determined the content (SiF3)2O.

Example 9

Used 100 ml fluoride polyvalent metal obtained in Example 8. Gaseous SiF4obtained in Example 1 was introduced into the reactor 8 (structural material of the reaction tube: Nickel, inner diameter: 8 mm, length: 1000 mm), shown in the drawing, through the valve 23 was introduced to 2.3 ml of 100% gaseous fluorine in the reaction between (SiF3)2O provided the Xia in SiF 4and fluoride polyvalent metal at 250°that was his regeneration under the action of F2. The samples of gas were taken through the valve 28 and analyzed. The results obtained are presented in Table 1. The results show that the concentration (SiF3)2O reduced approximately to 500 OBC/million analysis of the gas at the outlet of the reactor was continued, however, gaseous fluorine has not been detected, and the concentration (SiF3)2O did not change.

Table 1
The results of the analysis of the relevant components (about. h/million)
(SiF3)2ON2O2COCO2HFF2
Example 18650------
Example 21850------
Example 3<0,1-30,05,083,05,51680
Example 4<0,1-29,8the 4.783,65,6<0,1
Example 5Permeable party<0,1to 75.212,321214,2
Impervious party<0,188,70,5<0,10,5<0,1
Example 6<0,1<0,1<0,1<0,1<0,1<0,1-
Example 7Input<0,148,51,51,71879,3-
Output<0,1<0,1<0,1<0,1<0,1<0,1-
Example 80.5 hour<0,1------
2,0 h102------
Example 90.5 hour 460-----<0,1
4.0 hours480-----<0,1
-:the analysis was not performed

Industrial applicability

In accordance with the above information according to the present invention can be obtained SiF4not containing (SiF3)2O. in Addition, the impurity components can be analyzed in amounts up to 0.1 ppm or less, and can be obtained high-purity SiF4required for the production of components of electronic equipment, in particular for the production of element solar cells, semiconductors and optical fibers.

1. The method of receiving tetrafluorosilane, including the state (1) heating fluorosilicate preparation, stage (2-1) reaction of gaseous tetrafluorosilane containing exaptations formed in stage (1) with gaseous fluorine, stage (2-2) reaction of gaseous tetrafluorosilane containing exaptations formed in stage (1) with a fluorine compound polyvalent metal, or stage (2-1) reaction of gaseous tetrafluorosilane containing exaptations formed in stage (1) with gaseous fluorine, and article is Dios (2-3) reaction of gaseous tetrafluorosilane, obtained in stage (2-1) with a fluoride compound polyvalent metal.

2. The method according to claim 1, wherein stage (1) is conducted at a temperature of 400°C or higher.

3. The method according to claim 1, in which stage (2-1) is conducted at a temperature of 100-350°C.

4. The method according to claim 1, in which stage (2-2) or stage (2-3) is conducted at a temperature of 50-350°C.

5. The method according to any one of claims 1 to 4, in which the fluorosilicate preparation represents at least one compound selected from the group consisting of fluorosilicate preparation of an alkali metal or fluorosilicate preparation of alkaline earth metal.

6. The method according to claim 1, wherein the fluorosilicate preparation pulverized and dried before carrying out stage (1).

7. The method according to claim 1 in which the fluoride compound polyvalent metal is at least one compound selected from the group consisting of CoF3, MFN3, MFN4, AgF2, CeF4,PbF4and K3NiF7.

8. The method according to claim 1, in which the use of a fluorine compound polyvalent metal on the media.

9. The method according to claim 8, in which the carrier is obtained by fluorination of at least one compound selected from the group consisting of aluminum oxide, titanium oxide and zirconium oxide.

10. The method according to claim 1, in which stage (2-2) or stage (2-3) is conducted in the presence of fluorine gas.

11. The method according to claim 1, including with adieu (3) contacting silicon with gaseous tetrafluorosilane, obtained in stage (2-1), stage (2-2) or stages (2-1) and (2-3).

12. The method according to claim 11, in which stage (3) is conducted at a temperature of 50°C or higher.

13. The method according to claim 11 or 12, in which before carrying out stage (3) the silicon is subjected to heat treatment in the presence of inert gas at 400°C or higher.

14. The method according to claim 11, comprising a stage (4), which consists in contacting gas obtained in stage (2-1), stage (2-2), stages (2-1) and (2-3), stages (2-1) and (3),stages (2-2) and (3), or stages (2-1), (2-3) and (3)the gas separation membrane and/or molecular-sieve carbon.

15. The method according to 14, in which the gas separation membrane is a SiO2-ZrO2ceramic membrane and/or poly(4-methylpentene-1) heterogenizing membrane.

16. The method according to 14, in which the molecular sieve carbon has a pore size 5Å or less.

17. High purity tetrafluorosilane containing exaptations in the number 1 ABC/m or less, obtained by the method according to any one of claims 1 to 16.

18. High purity tetrafluorosilane on 17 containing exaptations in an amount of 0.1 ABC/m or less.

19. The method according to claim 1, which further provide a method of analyzing impurities in high-purity tetrafluorosilane, which consists in contacting tetrafluorosilane containing as impurities gaseous H2, gaseous O2 , gaseous N2, gaseous, gaseous CH4and/or gaseous CO2as impurities with the adsorbent, with the aim of separating these impurities from tetrafluorosilane, and the introduction of said impurities together with the carrier gas into the gas chromatograph for analysis of impurities to control the resulting high-purity product.

20. The method according to claim 19, in which the adsorbent is an activated carbon, spherical activated carbon-based petroleum pitch and/or molecular-sieve carbon with pore size 6Å or more.

21. The method according to claim 1, in which the method of analysis of impurities in high-purity tetrafluorosilane is the introduction of tetrafluorosilane containing exaptations as an impurity in the optical cell, the window which is made of a metal halide, and analysis of hexaphenyldisilane and/or hydrogen fluoride by the method of infrared spectrometry.

22. Gas intended for the production of optical fibers, including gaseous tetrafluorosilane obtained by the method according to any one of claims 1 to 16.

23. Gas, intended for the production of semiconductors, including gaseous tetrafluorosilane obtained by the method according to any one of claims 1 to 16.

24. Gas, intended for the production of the solar battery element comprising gaseous tetrafluorosilane obtained the method according to any one of claims 1 to 16.



 

Same patents:

FIELD: semiconductor technology; production of microelectronic devices on the basis of substrates manufactured out of III-V groups chemical element nitride boules.

SUBSTANCE: the invention is pertaining to production of microelectronic devices on the basis of substrates manufactured out of III-V groups chemical element nitride boules and may be used in semiconductor engineering. Substance of the invention: the boule of III-V groups chemical element nitride may be manufactured by growing of the material of III-V groups the chemical element nitride on the corresponding crystal seed out of the same material of nitride of the chemical element of III-V of group by epitaxy from the vapor phase at the speed of the growth exceeding 20 micrometers per hour. The boule has the quality suitable for manufacture of microelectronic devices, its diameter makes more than 1 centimeter, the length exceeds 1 millimeter, defects density on the boule upper surface is less than 107 defects·cm-2.

EFFECT: the invention ensures manufacture of the microelectronic devices of good quality and above indicated parameters.

102 cl, 9 dwg

FIELD: microelectronics; methods of manufacture of microcircuit chips.

SUBSTANCE: the offered invention is pertaining to the field of microelectronics, in particular, to the methods of manufacture of microcircuit chips. The offered method includes a loading of semiconductor slices in a reactor having hot walls perpendicularly to a gas stream, pumping-out of the reactor air up to the ultimate vacuum, introduction of monosilane for deposition of layers of polycrystalline silicon, silane supply cutoff, pumping-out of the reactor air up to the ultimate vacuum, delivery of a noble gas into the reactor up to atmospheric air pressure, unloading of the semiconductor slices from the reactor. After introduction of the noble gas into the reactor conduct an additional thermal annealing of layers of polycrystalline silicon at the temperature of no less than 1323K, then keep the slices at this temperature during 40-60 minutes in a stream of noble gas and reduce the temperature down to the temperature of the polycrystalline silicon layers growth. The technical result of the invention is a decrease of heterogeneity of resistance of the polycrystalline silicon layers.

EFFECT: the invention ensures a decrease of heterogeneity of resistance of the polycrystalline silicon layers.

1 dwg, 2 tbl, 1 ex

FIELD: metal science; protection of materials against external and corrosive attacks.

SUBSTANCE: proposed method for producing diamond-like films designed for encapsulating solar photocells to protect them against chemical, radiation, and mechanical damage includes variation of ion kinetic energy, plasma discharge current, and spatial density distribution of plasma incorporating C+, H+, N+, and Ar+ ions by acting upon ion current from radial source with electric field built up by stop-down, neutralizing, and accelerating electrodes. Spatial plasma distribution is checked for uniformity by measuring plasma current density on solar photocell surface whose temperature is maintained not to exceed 80 oC. In the process substrate holder makes complex axial movement in three directions within vacuum chamber. Diamond-like films produced in the process on solar photocell surface area over 110 cm2 are noted for uniformity, difference in their optical parameters variable within desired range is not over 5%.

EFFECT: enhanced adhesive property, microhardness, and resistance of films to corrosive attacks.

5 cl, 12 dwg, 2 tbl

The invention relates to semiconductor electronics, namely, to obtain a multilayer epitaxial silicon structures with ultrathin layers of gas-phase method
The invention relates to new materials of electronic technology and the production technology

The invention relates to the technology of production of amorphous silicon films

The invention relates to the field of electrical engineering and can be used in the construction of fiber-optic cables when the structures of fiber-optic communication lines

The invention relates to the field of electrical engineering and can be used in the construction of fiber-optic communication lines, built-in lightning protection cables high-voltage lines

The invention relates to electrical engineering and can be used in the construction of fiber-optic cables when the structures of fiber-optic communication lines

The invention relates to electrical engineering and can be used in the construction of the suspended optic cables in the construction of fiber-optic communication lines

The invention relates to optical fiber cables that are supported throughout the system through the towers (towers, poles, or other vertical supports that are also used to support electrical power cables

The invention relates to the field of electrical engineering and can be used in the construction of fiber-optic communication lines, built-in lightning protection cables high-voltage lines

The invention relates to electrical engineering, can be used in the construction of fiber-optic communication lines, built-in lightning protection cables high-voltage lines
Up!