KR930007991B1 - Preparation and Purification Method of Group III-A Organometallic Compound - Google Patents

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Description

Preparation and Purification Method of Group III-A Organometallic Compound

The present invention relates to a method for preparing and purifying a volatile organometallic compound having the following structural formula.

M ¹ R _a

Wherein M ¹ is an element of group III-A of the periodic table; R is hydrogen and hydrocarbyl, respectively. And combinations thereof; And "a" is an integer determined by the valence of M ¹ , typically 3.

Organometallic compounds of group III-A elements of the periodic table, and in particular lower alkyl compounds of these elements, are widely used for the deposition of compounds of the member elements on substrates by chemical vapor deposition. For example, a gallium arsenide semiconductor layer is deposited on a substrate by combining a vapor of a gallium source such as trimethylgallium with an arsenic source such as arsine at elevated temperatures in the presence of a suitable substrate. Similar processes are used to form indium phosphide from other Group III-V compounds such as trimethylindium and phosphine. Group III-A compounds are preferably supplied as a liquid, from a bubbler (bubble generator), where the compounds are evaporated in a carrier gas stream for transport into the deposition chamber. Therefore, this mode of transport preferably is such that the organometallic source of the III-A compound is volatile and is present in the liquid state at temperatures between about 0 ° C and 150 ° C.

Group III-A compounds for chemical vapor deposition, in particular the formation of III-V compounds, need to have a high degree of purity so that they can produce coatings with grades required for electronic and other demanding applications. When the compounds are transferred from the bubbler to the liquid state, non-volatile impurities are not particularly important because they do not evaporate in the bubbler device and as a result are not transported to the substrate. However, volatile impurities enter the deposition chamber and therefore must be minimally present in the chemical intermediate deposition source compound. Even a few ppm of impurities can greatly affect the properties of the deposited film. See, Jones, et al., "Analysis of High Purity Metalorganics by ICP Emission Spectrometry," Journal of Crystal Growth. Vol. 77, pp. 47-54 (1986), especially. Page 47, column 1 (this article is not a qualifying prior art)

One further deteriorating factor is the difficulty of separating volatile III-A members by physical means because many interfering solvents and organometallic compounds are volatile. For example, in the paper cited above, Jones. et al. described the difficulty of removing volatile micro impurities from group III-A alkyl compounds by distillation.

A specific example of organic contamination of group III-A alkyl compounds is the presence of complexed ethers in trialkylindium compounds prepared in ether solvents. Ethers are tightly complexed and cannot be separated. Conventional attempts to separate complex ethers have been repeated distillation at high temperatures, which not only wastes most good products but also does not remove all complex ethers.

The Jones paper cited above indicates that Group III-A organometallic compounds can be removed from organometallic and organic impurities by forming non-volatile adducts of good organometallic compounds with 1,2-bis (diphenylphosphino) ethanol. It was said. Substances that do not form ethers, other organic impurities, and adducts containing organometallic compounds such as tin, silicon, zinc, etc. can be removed by evaporation, although these substances are volatile, but the adducts are not. (I.e. volatile). The adduct decomposes to release good volatile organometallic compounds. Preferred compounds are removed and recovered from the nonvolatile 1,2-bis (diphenylphosphino) ethane by distillation. One big problem with the Jones, et al. Process is the need to decompose the adduct by heating.

If the adduct decomposition temperature is high, it may approach or exceed the decomposition temperature of a good compound.

The second problem is that the additives of the Jones et al. Process produce adducts with volatile organometallic compounds of elements other than group III-A elements.

These interfering compounds emit when the adduct decomposes, unless the adduct thereof decomposes at a substantially higher temperature than the adduct of a good organometallic compound. Thus, the Jones et al. Process cannot isolate all unfavorable impurities.

Many commercial Group III-A alkyls on the market contain up to about 1 ppm of impurities; Such compounds are often said to have "six nine" or "six N" purity, and they exhibit at least 99.9999% purity. In other words, these compounds contain 1 ppm (parts per million) of impurities. However, a common commercial standard for purity is the content of nonvolatile components present in the material. Nonvolatile impurities are of less interest than volatile impurities, and volatile impurities are generally not measured, since the degree required for the purity of these compounds is not directly related to their utility for chemical vapor deposition of films.

Volatile impurities (other than solvents) can be measured using inductively coupled plasma atomic emission spectral analysis with particular care to retain volatile impurities in the sample during analysis (see, US Patent Number 4, 688, 935, issued Agust 25, 1987 by Barnes et al., Cited in the text.). Volatile impurities (including solvents) can also be detected by mass spectrum under conditions that impurities remain in the sample during analysis. This analysis showed that commercial materials did not have optimal purity. Materials having a purity of "six nine" for nonvolatile components are considered to have a purity of "five nine" or less for volatile components such as silicon alkyl and (gallium compound) zinc alkyl.

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The periodic table group III-A elements denoted as M ^{1 in the} present specification are boron, aluminum, gallium, indium, and thallium, and aluminum, gallium, and indium are generally preferred for preparing a III-V compound.

Elements of group IA and II-A of the periodic table denoted by M ² include hydrogen, lithium, sodium, potassium, rutidium, cesium, francium, beryllium, magnesium, calcium, strontium, barium, and radium. Of course lithium, sodium, potassium and magnesium are preferred, with lithium being most preferred. Ammonium is also extreme within the M ² definition.

Elements of group II-B of the periodic table include zinc, cadmium and mercury. These are denoted M ³ in the text.

The elements of group IA of the Periodic Table are sometimes called M ⁴ to distinguish them from the elements of Group II-A of the Periodic Table.

"Hydrocarbyl" is broadly defined as any organic radical, which produces organometallic compounds with III-A metals. Preferred hydrocarbyl species are alkyl groups, specifically lower alkyl groups (defined as alkyl groups having from 1 to 4 carbon atoms). Specifically all isomers of the methyl, ethyl, propyl, and butyl components are considered hydrocarbyl species. Other examples of hydrocarbyl components include saturated or unsaturated cycloalkyl having from about 5 to about 12 carbon atoms, most preferably cyclo pendienyl; Aryl, preferably phenyl or phenyl substituted with one or more lower alkyl constituents; And any of the above components substituted with nitrogen, oxygen, or another hetero atom. "R" as defined above is selected from hydrocarbyl and hydrogen.

"a" is an integer measured by the valence of M ^l . Typically 3. "b" is an integer measured by M ² valence, typically selected from group IA of the periodic table and M ² is 1, and M ² is 2 when selected from group II-A.

"X" as used above includes (but is not limited to) halogens, carboxylates (e.g. acetates), nitrates, etc. as suitable anions, preferably halogens, most preferably chloride ( Chloride) because it is a chloride of a relatively inexpensive III-A compound with commercially available purity.

"Distillation" as defined above includes all processes in which the separation is carried out by selectively evaporating (including sublimation) the ingredient mixture into one or more ingredients and then transporting the vapor elsewhere. Therefore, distillation includes a process of condensation without recovering steam.

As used above, "micro impurities" refers to detectable impurities present in a good compound at a concentration of about 20 ppm or less. "Substantially free" means that it contains less than 1 ppm of certain impurities. The abbreviation "Parts per million" is ppm and represents impurity parts by weight per million parts by weight of impurity compounds.

If one component can be made substantially free of other components by physical separation such as midstream without chemical reactions, the mixture of two compounds can be said to be in a "separable" state. If the separation cannot be done according to the test described above, the compounds can be said to be in an "inseparable" state.

"Solvent" broadly includes the true solution component as well as the liquid medium of the suspension or slurry. A "solvent" refers to a solvent that cannot be separated from the target compound, because the solvent produces a complex that resists decomposition by distillation.

All other solvents are "noncomplexible" solvents. The most important wear medium in the text is ether. Specific examples of non-complexing solvents for this purpose are solvents which do not contain electron donors such as oxygen, nitrogen or sulfur. Acceptable noncombustible solvents include aliphatic hydrocarbons such as pentane or hexane, chlorinated aliphatic solvents such as chloroform or carbon tetrachloride, aromatic solvents such as benzene and naphthalene, aliphatic-substituted aromatic solvents such as toluene and xylene, chloro Heterosubstituted aromatic solvents such as benzene and the like.

"Ether" as defined above refers to diethyl ether in the working examples. Other "ethers" include other ethers, including cyclic ethers such as tetrahydrofuran.

"Volatile" compound refers to a compound having a room temperature vapor pressure of 30 milltorr or more. "Non-volatile" material refers to a material having a room temperature vapor pressure of 30 milltorr or less.

The purpose of the present invention, which refers to the preparation or purification of a compound previously prepared by the production, separation and decomposition of adducts of the compound, is an object of the Group III-A organometals with a total volatile organometallic impurity of preferably 1 ppm or less To prepare a compound.

It is a first aspect of the present invention to provide a method for preparing a compound having the following formula:

M ¹ R _a

As a first step of the process, a nonvolatile intermediate compound (adduct) is prepared, which compound has the following structural formula.

_{^{[M 1 R (a + 1}} )] b - [M 2] + b

The adduct is formed in the presence of volatile impurities to be removed, which once formed cannot be separated from the target compound. Volatile impurities in which adducts comprising complexing ethers are present can be removed by evaporating the volatile impurities to separate their vapors from the intermediate compounds. The adduct was then decomposed to form the target compound. Preferably the decomposition is carried out according to the following reaction:

_{^{C [M 1 R (a +}} 1)] b - [M 2] + b + dM 1 X a → eM 1 R a + fM 2 X b

Wherein X is a suitable anion, preferably halogen, and c, d, e and f are integers that fit the equation. Finally, a postdistillation step is used to separate the desired compound from residual organometallic (specifically silicon alkyl) impurities. Surprisingly, the inventors have found that residual silicon alkyl and other impurities can be removed by distillation as opposed to the teaching that distillation cannot be used to remove micro impurities in volatile organometallic compounds from the volatile organometallic target compound described by Jones et al. Found.

The first advantage of the decomposition process in this process is that the yield of the target compound is increased because the decomposition agent is a metal compound in the target compound, and the second advantage obtained by introducing this reaction is that the decomposition product is a volatile target compound, group 1-A or It is a nonvolatile compound of group III-A metal. Volatile products can easily be separated by distillation using different volatilities of the two products of the decomposition reaction.

The third advantage of this process is that it does not depend entirely on heat to decompose the adducts and release the desired compounds. Unlike conventional adduct processes, the adducts herein can in most cases decompose at room temperature or even lower temperatures.

A fourth advantage is the avoidance of the introduction of other metals in which the compound of M ¹ used as the disintegrant may remain as a contaminant.

In this process, intermediate compounds can be produced in a variety of ways. Several synthetic examples are provided later in this specification.

A second aspect of the present invention is to provide a method for separating volatile organometallic II-B iso impurities from volatile organometallic III-A compounds. The first utility of this process is at the initial stage of the first process. The first step of the separation process is carried out by providing a volatile Group III-A compound containing at least one volatile Group II-B compound as micro impurities. Group III-A compounds and micro-impurities each have the following structural formula:

M ¹ R _a ,

And

M ³ R ₂ ,

This mixture is reacted with an additive below the chemical equivalent content relative to the M ¹ compound. The production of adducts of M ¹ compounds is somewhat more advantageous than the production of adducts of M ³ compounds. Thus, the result is that an adduct with the formula

_{^{[M 1 R (a + 1}} )] b - [M 2] + b

A small amount of M ¹ R ₂ and almost all micro impurities of M ³ R _a remain unreacted residues. Since these starting materials are volatile and the adducts are nonvolatile, the starting materials can be removed from the adducts by a distillation process. The adduct is then decomposed and the target compound M ¹ R _a is removed from the nonvolatile decomposition product by distillation.

The first step is to produce a nonvolatile intermediate compound having the formula:

_{^{[M 1 R (a + 1}} )] b - [M 2] + b

This adduct can be produced in a variety of ways.

In a first specific example, the starting material is a non-pure version of the target compound. In this case, the production and final decomposition of the adduct is a purification process.

The intermediate compound is produced from the non-pure target compound by reacting the latter compound with M ² , an organometallic compound, according to the following scheme.

_{^{bM 1 R a + M 2 R}} b fM 2 X b → [M 1 R (a + 1)] b - [M 2] + b

In this reaction, M ² R _b , which is a preferred addition compound, is alkyl lithium, preferably methyllithium, which forms a complex upon reaction with the volatile organometallic compounds of Groups II-B and III-A. It does not react with volatile compounds of other elements to produce nonvolatile adducts. Thus, when the adduct decomposes and the volatile target compound is separated by distillation, the volatile compounds of the other components can be easily removed from the adduct by distillation, while the nonvolatile compounds of the other components remain intact.

Another advantage of these additives is that the reactants are complexed with ether, and since the ether complexes more loosely in the intermediate compound, the adduct can be removed by slow heating. Although ethers are complexed, for the purposes of this specification ethers are considered to have an impurity that can be separated to the extent that they can be removed from the intermediate compound by distillation.

The second method of producing an intermediate compound from the same impure starting material as the target compound is to react the starting material with the metal M ⁴ according to the following reaction:

_{^{CM 4 + dM 1 R a →}} c [M 1 R (a + 1)] b - (M 4) + b + eM 1

Wherein c, d, and e are integers with the values necessary to fit the equation, M ⁴ is selected from group IA, and group II-A metals are excluded.

This method is usually less desirable than the first reaction described above for producing intermediate compounds. One of the nonvolatile products is the target compound of the free metal, and some target compounds are not reconstituted for the purpose of the process. This problem can be alleviated by recycling organometals to modify alkyl metals or other compounds. If this process is introduced, M ⁴ is preferably lithium or sodium.

A third method for producing intermediate compounds is obtained by carrying out the following reaction:

In this process, the preferred metal alkyl is alkyllithium, most preferably methyllithium. Preferred M ¹ X _a , the reactant are metal chlorides of the desired compound. The advantage of this reaction is that nonpyrophoric reactants M ¹ X _a are generally produced from non-flammable reactants without ^first producing _a flammable compound M ¹ X _a .

After producing the intermediate compound, the next step is to separate the intermediate compound from all volatile impurities by distillation. This step will remove volatile starting materials that do not produce nonvolatile adducts.

In addition, non-combustible solvents can be removed because there is no particular interference with their evaporation and removal. Also complexing solvents, in particular ethers, are removed at this stage since it is not difficult to separate the ether complexes with adducts as complexes of ethers with organometallic compounds. This is because the target compound is an indium compound, which is typically produced only in an ether solvent and cannot be separated from the ether. Ether is an _{^{[M 1 R (a + 1}} )] United before the additional water is produced ^- is considered that rather than adding ion having a [M ^{2] + b} complexed ions loosely in the water.

Separation of volatile impurities and starting materials can be done by heating the reaction product, by applying partial vacuum or full vacuum in the chamber in which the adduct is contained, or a combination of these methods.

After removal of separable volatile impurities, the adduct is decomposed to release the desired compound which is volatile. The remaining adduct is nonvolatile.

A less preferred but sometimes available method for the decomposition of intermediate compounds is to heat the intermediate compound, a method that has been performed in other additional methods described in the prior art section of this specification. If this method is done, the disadvantages of other additional processes can also be foreseen.

A preferred method of digesting the adduct is to react the adduct with the reagent. If the preferred reagent M ¹ X _a is a metal compound of the desired compound, the yield can be increased. Preferred reactors for decomposing intermediate compounds are as follows:

_{^{c [M 1 R (a +}} 1)] b - [M 2] + b + dM 1 X a → eM 1 R a + fM 2 X b

Where c, d, e and f are integers necessary for fitting the reaction equation.

If the adduct is produced by adding M ¹ X _a , an additional amount of the same reagent can be added to decompose the adduct. Thus, if such a production and decomposition apparatus is introduced, it is not important to add an excess amount of adduct generating reagents at first, because too early regeneration of the target compound can be avoided. However, if this precaution is not important, if a small amount of the target compound is produced when the adduct is produced, it will be removed during the step of removing volatile impurities.

Finally, fine impurities are removed by distillation and decomposition steps. The distillation pot is heated to a degree sufficient to dissolve the target compound and remove the mid- impurities from the target compound. The surprising aspect of the post-distillation step is that even if a large amount of impurities cannot be removed directly by distillation and must be removed by adduct production and decomposition processes, it is possible to obtain a target compound having almost no fine impurities.

A second aspect of the present invention is to provide a method for separating Group II-B impurities from Group III-A organometallic compounds. This process can be used as a precursor for carrying out any of the processes described previously or as a precursor for separating these organometallic compounds for any other purpose.

The first step is to provide a mixture of most Group III-A compounds and volatile Group II-B organometallic micro impurities. The target compound and microimpurity each have the following structural formula.

M ¹ Ra

And

M ³ R ₂

Since each component of this mixture is volatile and it is difficult to separate the components by physical process, the target compound is almost free of impurities.

This mixture reacts with additives up to chemical equivalent content. The additive may be a reactant or a combination of reactants as described above capable of producing the intermediate compound described above.

An important aspect of this process is that when both compounds are present, the compounds of M ^{l form} complexes more easily than the compounds of M ³ . If an additive below the chemical equivalent content is used, only the compounds of M ¹ present will produce the adduct.

The volatile components are then separated from the adduct as before. Since the compounds of M ³ cannot form complexes and are volatile, they can be removed by a separation process like other volatile impurities.

The adduct is then decomposed to modify the desired compound of M ^l as described above. The decomposition products of the adducts are organometallic compounds of M ^{1 which} have few compounds of M ³ .

EXAMPLE

The following examples are intended to illustrate various aspects of the invention. However, the scope of the invention is defined by the claims that determine this specification. All operations described in the examples are carried out under vacuum or under an inert atmosphere of nitrogen or argon gas. Anhydrides of all reactants and products mentioned in the text.

In this part, the following reactions take place: ("Me" is methyl):

1500 g (6.78 moles) of InCl ₃ was weighed into a glove bag and placed in a 121, three necked flask previously filled with vacuum and nitrogen. The 12ι flask was placed on a heating mantle and supported by a large jack stand.

The 12ι reaction flask was then equipped with an 18 inch (46 cm) Vigreux column connected to a 5ι, 3-neck receiver with a 1ι auxiliary funnel, a mechanical stirrer, and a Claisen had ("Vigreux" and "Claisen" under the trade names). I don't think). Connect the 5ι receiver to the nitrogen bubbler. A methyl lithium source (1.5 molar low halides in dimethyl ether) is connected to a 1ι secondary funnel through a stainless steel tube.

The drip tip of the auxiliary funnel extends under the greased connection because MeLi is responsive to halocarbon grease.

About 2ι of diethyl ether was sucked up into a pressure absorber and placed in a 12ι reaction flask to prepare a stirrable slurry with InC1 ₃ . The 5ι receiver and dry ice condenser were cooled with a mixture of isopropanol (IPA) and dry ice before the MeLi addition was started. The reaction was carried out under reflux, and the ether was distilled off from the Vigreux column and recovered in a 5ι receiver. It is not necessary to heat the reaction flask with sufficient heat of reaction to maintain reflux.

The addition of MeLi continues until 4.4 moles of MeLi are added per mole of InCl ₃ . The concentration of MeLi is determined by recovering 10 ml several times and titrating with a standard acid solution (0.1 N hydrochloric acid). When the 12ι reaction flask is filled, the addition of MeLi is stopped and the ether is distilled off by heating the reaction temperature to reflux using a heating mantle. The distilled ether is sucked up into the absorption tube and the receiver is emptied several times during fixation. The total volume of MeLi solution added was about 20ι (4.4 moles of MeLi per mole of InCl ₃ ).

After adding MeLi to the 12ι reaction flask, the auxiliary funnel was removed and replaced with a nitrogen inlet tube with a shutoff valve. The ether was distilled off until the reaction flask was heated with a heating mantle until the volume of the reaction mixture was 5 or less. At this point, stirring was stopped and the reaction mixture was left to rest overnight.

Vigreux columns, claysen heads, and receivers were removed from the reaction flask. The reaction mixture consisted of a white precipitate (polymer of LiCl and methylligap), which precipitated on the bottom of the orange solution.

Example 1, Part 2 ... Vacuum drying of LiInMe ₄

A 5ι stainless steel kettlehead drying flask with a three-neck glass top (0-ring seal) was equipped with a nitrogen inlet tube with a shutoff valve and agitator. This drying flask was connected to a 5ι, 3-necked receiver equipped with a dry ice condenser with a U-tube. The condenser was connected to a valve, liquid nitrogen trap, vacuum gauge, second valve and vacuum pump, which were arranged in sequence via a vacuum tube. The stainless steel dry flask was heated in an oil bath and supported on a combined heating / stirring plate and jackstand. The device was evacuated and filled with nitrogen several times.

After raising the 12ι reaction flask containing the reaction mixture from Part 1, the orange solution is passed through a non-reactive flexible tube into a 5ι stainless steel drying flask, taking care not to overflow the precipitate of LiCl and excess polymerized MeLi.

Most of the orange solution (intermediate compound) of LiInMe ₄ in ether was removed from the 12ι reaction flask, and then 2-3 2-3 ether was suctioned into the 12ι flask to wash the precipitate. The mixture was stirred for at least 1 hour and then left overnight.

Drying was slowly added to the 5ι dry flask to remove ether. The oil bath temperature was maintained at about 30 ° C. to compensate for the heat loss caused by the evaporation of ether. Receiver and condenser were cooled with a dry ice / IPA slurry. During this step, distilled ether was periodically aspirated out of the receiver.

After reducing the volume of material in the 5ι dry flask to 2ι or less, the pale yellow supernatant obtained from the 12ι reaction flask was aspirated and placed into the 5ι dry flask, taking care to leave a precipitate.

After the vacuum was slowly applied again to the drying apparatus, the oil bath temperature was gradually raised. This process reaches full vacuum and continues until the oil bath temperature reaches 120 ° C. LiInMe ₄ was dried at voltage and 120 ° C. for several hours. The device was charged with nitrogen through a nitrogen inlet tube shutoff valve on a 5ι flask and then cooled to room temperature.

U-tubes and receivers were removed in a 5ι stainless steel dry flask. The stainless steel flask was placed in a 5ι, three necked glass flask equipped with a stainless steel bowl and two nitrogen inlets with a glove bag, funnel, spatula and mechanical stirrer and shutoff valve.

After the glass top was removed from the stainless steel dry flask, the tan solid LiInMe ₄ adduct was ground to a fine powder using a bowl and pestle. After crushing the adduct, the powder was transferred to a 5ι glass flask.

The flask containing LiInMe ₄ was placed in an oil bath and connected directly to a liquid nitrogen trap with a vacuum tube. After the voltage was applied to the flask, the oil bath temperature was raised to 120 ° C. Under these conditions, LiInMe ₄ was dried for at least 2 hours, filled through a 5ι flask, and cooled to room temperature.

The dry LiInMe ₄ weight was then measured to calculate the weight of InCl ₃ required for the next reaction.

Example 1

Part 3 ‥‥ LiInMe ₄ disassembly

The dry LiInMe ₄ prepared in Part 2 was weighed and the weight of InCl ₃ required for the final reaction was calculated.

In a glove bag, a stoichiometric amount of InCl ₃ was immersed and placed in a 2ι, 1 neck flask. The flask was equipped with a large diameter tube about 2ft in length with a male joint and a small flask at the end. In a 5ι flask containing LiInMe ₄ , about 2ι of benzene was sucked in and poured into a stirring slurry. After the 5 ι flask was placed in the oil bath, a magnetic tube was installed to install a dry ice condenser and a thermowell was installed in a 1 구 5 ι flask. After a small "dummy" flask was removed from the tube tip connected to the InCl ₃ flask, the daily joint of the tube tip was connected to a 5ι flask.

InCl ₃ was slowly transferred to the LiInMe ₄ / benzene slurry. The rate of addition is added at such a rate that the reaction temperature can be maintained below the reflux temperature of benzene (80 ° C.). Prevent the tube between the addition of the aliquot of InCl ₃ with a clamp to prevent the wet from which benzene vapor and clusters in the InCl ₃ tube. The addition of InCl ₃ required several hours.

After complete addition of InCl ₃ , the reaction mixture was cooled to room temperature with stirring. The InCl ₃ addition flask and tube were removed and replaced with a nitrogen inlet tube with a shutoff valve. The Y tube, the dry ice condenser and the hot wall were removed.

Example 1

Part 4 ‥‥ Removal of Benzene and Micro Impurities by Distillation

In the Part 3 5 reaction flask, a 18 inch (46 cm) Vigreux column was connected to a 3 receiver in a Westcott water condenser. ("Westcott" is not considered to be a trade name.) The receiver is cooled in an ice bath, followed by distillation at atmospheric pressure to distill off benzene from the reaction mixture. The oil bath was maintained at about 110 ° C. and the head temperature was about 80-83 ° C. After most of the benzene was distilled off, the reaction mixture became thick. The stirrer shaft was lifted a few inches and the shaft paddle was hung above the height of the molten reaction mixture, clamped at this position and the reaction flask was cooled midnight.

The following day, the stirring shaft was removed from a 5ι reaction flask containing a solid mixture of InMe ₃ , LiCl and benzene. A 3ι, 3-necked flask equipped with a stirrer and a dry ice condenser was connected to a 5ι flask with a U tube. U-tubes were covered with heat tape. A dry ice condenser was connected to the valve, liquid nitrogen trap, pressure gauge, valve and vacuum pump (in order) using a vacuma tube.

System vacuum was applied at room temperature. Receiver and condenser were kept at room temperature. Benzene was passed through a liquid nitrogen trap. When the trap begins to block with frozen benzene, close the valve on both sides of the trap. After removal from liquid nitrogen, benzene is dissolved and dropped to the bottom of the trap, the trap is then dewar flasked with liquid nitrogen ("Dewar" is not considered a trade name).

The oil bath was warmed to 30-35 ° C. to prevent benzene from freezing in the 5ι flask, and the U-tube was warmed with hot tape to prevent benzene from freezing in the U-tube. When InMe ₃ crystals began to be recovered in the receiver, the receiver and dry ice condenser were cooled with dry ice / IPA. After the oil bath temperature was warmed up to 50 ° C., sublimation was continued.

About 9 days were required to sublime 1 kg of InMe ₃ . Every morning the above starting procedure was repeated to remove traces of benzene from InMe ₃ . After several days of sublimation, the reaction mixture was cooled while carefully chopping the reaction mixture with a spatula in the morning. After completion of the sublimation, the device was charged through a nitrogen inlet tube on a 5ι flask. Sublimation was terminated when fine, pale brown solid LiCl remained in the 5ι flask.

Example 1

Part 5 ‥‥ Sublimation and Separation of Micro-Impurities

After disassembling the apparatus that was used in the beginning of the sublimation InMe _3, the self-3ι flask containing a sublimation InMe ₃ and stirred using a U tube and connects to a small dry ice condenser was attached 1ι receiver.

Heat the heat tape wrapped in the U-tube. Under atmospheric pressure, the 3ι flask in the oil bath is heated to 90-110 ° C. to completely dissolve InMe ₃ . The dissolved InMe ₃ is stirred with a stirrer.

Receiver and condenser were cooled with dry ice / IPA. The nitrogen inlet valve was then sealed on the 3ι flask and the pressure in the system was slowly depressurized until InMe ₃ started bubbling. The depressurization of the system was carefully continued until about 20-30 g of material was recovered in the receiver. At this point, the device was charged through a 3 flask and cooled to room temperature throughout the night.

The 1ι receiver containing the components was replaced with a 3ι, three neck flask equipped with a dry ice condenser. Sublimation was restarted and 1st sublimation was performed according to the starting procedure mentioned above. Sublimation was continued until only about 50 g of material remained in the heated flask. Second sublimation was carried out in the same manner as in the first sublimation, and continued for the same time. Full vacuum was applied every morning under receive mounting at room temperature before cooling the system to -78 ° C as first sublimation. This procedure helped to remove traces of benzene in InMe ₃ .

After completion of sublimation, the system was filled and disassembled. Nitrogen shutoff valves were fitted to a 3ι flask containing InMe ₃ sublimated. After InMe ₃ was warmed to room temperature throughout the night, the 3ι flask was attached directly to a liquid nitrogen track, followed by complete vacuum at room temperature for 1 hour. The 3ι flask was then placed in a dry box and vacuumed for storage.

The product was analyzed by inductively coupled plasma atomic emission spectra and contained only 1 ppm of silicon.

Example 1

Part 6 ‥‥ InP Film Growth

The indium phosphide semiconductor layer was grown using the product of Part5 and phosphine gas in an atmospheric vapor phase epitaxy process. The layer was used to measure electrical properties. The electron mobility of the layer at 77k was 131,000, which is the highest value ever obtained, indicating that there are very few solvents and organometallic impurities in the original compound.

Example 2

Removal of Zn and Si from Trimethyl Potassium

Part1: Preparation of LiGaMe ₄

The following reactions take place:

Starting trimethyl gallium (TMG) was analyzed for impurities of silicon and zinc by inductively-coupled plasma atomic emission spectra (ICP).

Volatile silicone alkyl compounds having an average concentration of 42 ppm and about 5 ppm of volatile zinc alkyl compounds have been found. The detection limit of each of these impurities was about 0.5 ppm.

A 12ι stainless steel kettlehead flask was equipped with a three necked glastop, an O-ring sealant, a magnetic stirrer, and a 1ι auxiliary funnel. The flask was evacuated to a pressure of 0.5 mm Hg (66 N / m 2).

1207 mL (1363 g, 11.87 moles) of TMG was added to the flask from the feed tank via a short hose via a sub funnel. The reaction was exothermic.

After completion of the MeLi addition, a 3ι receiver with a dry ice condenser, a liquid nitrogen trap, and a vacuum pump were connected (in order) to the 12ι flask. The ether was evaporated from the flask until the adduct in the flask was dry. Final pot temperature and pressure were 120 ° C., 0.4 mm Hg (53 N / m 2). The device was then charged with nitrogen, then the adduct was removed from the flask and decomposed under nitrogen atmosphere. It was then dried in a similar apparatus at 110 ° C. at 0.3 mmHg (40 N / m 2) pressure for about 1 hour. A small amount of unreacted TMG was separated in a liquid nitrogen trap and it was confirmed that sub stoichiometric MeLi was added intact. 1607 g (11.75 moles) of LiGaMe ₄ were isolated.

Example 2

Part2: Rebuild TMG

3 LiGaMe ₄ + GaC1 ₃ → 4GaMe ₃ + 3LiCl

1598 g (11.68 mol) of the Part 1 product was immersed and placed in a 12ι, three neck glass flask. One gallon (3.79ι) of toluene was placed into the flask by inhalation and then 325 ml of additional toluene was placed in an auxiliary funnel attached to the flask. 3.89 was used to add (about 255ml) of toluene were dissolved to a ₃ (685g) GaCl of moles of toluene in the auxiliary funnel, washing the upper top of the GaCl ₃ and addition funnel from GaCl ₃ ampoules. Gallium chloride / toluene solution was added to the adduct in the flask over about 2 hours.

Example 2

Raw Distillation of Part 3 -TMG

12ι flask with distillation column (vacuum jacket, silver-clad, packed in effective stainless steel packing), Claisen head. And a 1ι receiver equipped with a dry ice condenser. After the flask was heated in an oil bath, the receiver was kept at -78 ° C and the pot temperature was about 50 ° C and the head temperature was about 55 ° C. TMG began to distill and began to collect in the receiver. About 50 ml of TMG was recovered to the receiver. The recovered TMG was analyzed by ICP and contained about 3 ppm of silicon, and zinc could not be detected.

After replacing the receive vessel with 5? Receive flasks, the main fraction of TMG was distilled at a head temperature of 85 to 106 ° C. and a pot temperature of 100 to 116 ° C. About 2.5 ti of TMG was recovered.

Example 2

Part 4 ‥‥ 2 distillation

The 20 plate bubble column and 1 ι receiver with the head removed were assembled on the distillation flask, and then the TMG was distilled off again. The pot temperature was stable at 80 ° C. and the head temperature was stable at 55 ° C.

100 ml of TMG was recovered. TMG was analyzed by ICP and no silicon and zinc were detected. A larger receiver was installed and the main fraction of TMG was distilled over a pot temperature of 81-109 ° C. and a head temperature of 55-56 ° C. Finally, the remaining fractions were collected in a third receiver. Port residue was sampled for analysis.

Analysis of the major fractions revealed undetectable levels of silicon and zinc, as did port pot analysis.

This example showed that when MeLi below the stoichiometric content reacts with TMG, volatile zinc compounds (other volatile II-B compounds) are removed. The inventors believe that zinc does not form a complex under these conditions and is distilled off when the adduct is dried.

In addition, this example shows that the volatile silicone alkyls in the starting material are almost completely removed by distillation followed by generation and decomposition of the adduct.

Example 3

Preparation of LiGaMe ₄ from GaCl ₃

The following reactor mechanism was done:

A 5ι three neck flask was equipped with a 1ι cooperative funnel, a mechanical stirrer, and a dry ice condenser. After dissolving 250 g (1.42 mol) of GaC1 ₃ , the auxiliary funnel was briefly removed and poured into the flask.

400 ml of ether without gas to dissolve GaC1 ₃ was slowly added to the flask through a coping funnel. The dissolution was exothermic. Subsequently, about 1.3 M MeLi (about 5.7 moles) of 4.4 ι dissolved in ether was added to the flask via a copper tube connecting the MeLi tank to the auxiliary funnel. The reaction was exothermic and the reaction mixture was refluxed while MeLi was added. During the addition, a white precipitate of lithium chloride developed. The reaction mixture was stirred to complete the addition and cooled to room temperature. The mixture was filtered to separate the precipitate and the filtrate was dried. The product LiGaMe ₄ obtained here was a brown solid. The volatiles were held at a pressure of 0.5 mm Hg (66 N / m 2) or less and at a temperature of 127 ° C. for about 8 hours to release the volatiles from the product. The dry product was then triturated and weighed: 131 g (67% yield) of LiGaMe ₄ were produced.

The volatilities of LiGaMe ₄ were tested by heating a small amount of sample at a rate of 3 ° C./min starting at 150 ° C. At 220 ° C., no signs of melting or decomposition were detected. It started to decompose at 289 ° C. but did not melt.

Example 4

Tablet of AIEt ₃

Part 1 ‥‥ Generation of NaAlEt ₄

The following reactions were carried out (Note; "ET" is ethyl):

A 5ι three-necked flask was evacuated and filled with nitrogen. To the flask was added 5.6 moles (130 g) of sodium metal dispersed in toluene in a glove bag. The magnetic stirrer, dry ice condenser, and 1 ι auxiliary funnel were then connected to the flask, and the flask was placed in an oil bath. After about 3ι of toluene was added to the flask, the auxiliary funnel was filled with 540 ml (3.95 moles) of AlEt ₃ . After heating the oil bath to 70-75 ° C., AlEt ₃ was slowly added over about 2 hours. Once the exothermic reaction begins, turn off the heater in the oil bath. After the addition was complete, the flask was heated to 100 ° C., cooled and left for 3 days. The flask was heated to 65-70 ° C. with stirring and then stirring was stopped to precipitate residual Na and byproduct Al metal. The supernatant was decanted, pressure filtered, placed in a 5ι flask and heated to separate free metal. After cooling the filtrate, crystalline precipitate began to form. The filtrate was cooled in a -78 ° C bath to promote precipitation and the supernatant was decanted. Toluene was stripped off at 70 ° C. under vacuum for 2 hours. The final vacuum was below 1 mm Hg (133 N / m 2). After removing crystalline NaAlEt ₄ from the flask, the contents were scraped off with a spatula, and the precipitate was dried for about 4 hours at a temperature of 70-75 ° C. and a pressure of 0.5 mmHg (66 N / m 2), and then ground into a bowl and pestle. 263 g (1.58 moles) of NaAlEt ₄ were isolated. Its melting point is 122 ° C to 123 ° C. Values described in J. Gen. Chem. USSR, Vol. 32, p. 688 (1962), are 122-124.

Example 4

Part2 ‥‥ AlEt ₄ regeneration

The following reactor mechanism is used.

3NaAlEt ₄ + A1C1 ₃ → 4A1Et ₃ + 3NaCl

65 g AlC1 ₃ (0.49 moles) were weighed and placed in a small flask in a glove bag. The tube was attached to the flask; The outer end of the tube is equipped with a ground glass mail member temporarily inserted into the dummy flask. 263 g (1.58 moles) of NaAlEt ₄ were slurried with 1 mo of benzene in a 3 mo three-necked flask. The mail member of the tube was inserted into one of the three neck flasks, and AlCl ₃ was transferred to the three neck flasks in small portions over about 30 minutes. The solid component of the slurry was fine and turned into a precipitate of lean salts.

The volatiles were distilled off from the precipitate for about 15 hours under vacuum at 60-80 ° C. The precipitate was discarded. Benzene was distilled off under vacuum from AlEt ₃ at a pot temperature of 20 ° C to 45 ° C.

Replaced with a second receive flask and distilled AlEt ₃ and a small amount of benzene. All of the pot residue remained solid. The second receive flask was kept at 60 ° C. in vacuum (0.2 mm Hg. 27 N / m 2) for 3 hours to further remove benzene. No post distillation was performed.

Analysis of the product AlEt ₃ by ICP showed about 5 ppm of volatile silicone alkyls.

This example shows that even if adduct production and decomposition processes are carried out, poor concentrations of silicon alkyls remain in the reaction product unless a post-distillation step is introduced. In addition, this example shows one alternative reaction to produce an adduct from the target compound.

Example 5

Magnesium Adducts of TMG

The following reactions were carried out and the final product was purified in a similar manner to Example 2:

Me ₂ Mg + 2Me ₃ Ga → Mg (GaMe ₄ ) ₂

3Mg (GeMe ₄ ) ₂ + 2GaC1 ₃ → 8GaMe ₃ + 3MgCl ₂

The initial reaction was carried out in the absence of a small excess of Me ₃ Ga and Me ₂ Mg to prevent the formation of adducts of zinc impurities. ICP analysis showed undetectable volatile zinc and silicon compounds (0.5 ppm or less).

Example 6 Purification of Other III Alkyl Groups

The following reactions were carried out and the final product was purified in a similar manner as in Example 2:

MeLi + Et ₃ Ga → LiGaMe _x Et _y

(The sum of x + y is 4)

3LiGaMe _x Et _y + GaCl ₃ → 3GaMe _z Et _w + 3LiCl

(The sum of z and w is 3.)

The product represented in another way is a mixture of:

GaMe ₃

GaMe ₂ Et

GaMeEt ₂

GaEt ₃

Distilling off the mixture from the cracking byproduct converts both to a mixture of GaMe ₃ and GaEt ₃ , which boils at about 55 ° C. and 104 ° C., respectively, and can be separated by distillation.

A small molar excess of Et ₃ Ga was used in the first step to prevent the adduct formation of zinc impurities. ICP analysis could not detect the content of silicon and zinc in the product.

Claims (12)

A) producing a nonvolatile intermediate compound having the formula: _{^{[M 1 R (a + 1}} )] b - [M 2] + b Wherein M ¹ is a group III-A element, M ² is selected from components of group 1-A and II-A of the periodic table and ammonium, a is 3, b is selected from 1 or 2, and R is each selected from hydrocarbyl, hydrogen and combinations thereof, and the intermediate compound also comprises volatile organometallic impurities. B) distilling most of the volatile organometallic impurities from the intermediate compound to leave micro impurities of the volatile silicone compound mixed with the intermediate compound, C) decomposing the intermediate compound in accordance with the following reaction Providing M ¹ R _a mixed with impurities; And _{^{c [M 1 R (a +}} 1)] b - [M 2] + b + dM 1 X a → eM 1 R a + fM 2 X b Where c, d, e and f are integers satisfying the equation and x is an anion. D) post-distilling the MR _a mixed with the residue in a liquid state to selectively distill the residue from the MR _a to obtain a product containing the residue of 1 ppm or less. Process for preparing a product having. M ¹ R _a Wherein M ¹ is an element of group III-A of the periodic table; Each R is each selected from hydrogen, hydrocarbyl, and combinations thereof, a is 3, and the product contains up to 1 ppm total volatile metal compound impurities. The method of claim 1 wherein M is indium. The method of claim 1, wherein M ¹ is gallium. The method of claim ¹ wherein M ¹ is aluminum. The method of claim 1 wherein each R is an alkali. The method of claim 5. Wherein M ¹ R _a is trimethylindium. The method of claim 1 wherein M ² is lithium. The method of claim 1 wherein X is chloride. The method of claim 1 wherein the product of the process contains silicon and zinc in an undetectable amount. The method of claim 1 wherein the product of the process contains an undetectable amount of volatile organometallic impurities. The method of claim 1, wherein the product of the process is suitable for growing a semiconductor layer having an electron mobility of at least 131,000 cm 2 /V.S at 77 ° K. The method of claim 1, wherein the producing step is characterized by preferentially producing the non-volatile intermediate compound by reacting an impurity starting material having the following formula with an additive of less than stoichiometric content. M ¹ R _a Wherein M ¹ R and a are as defined above.