JP2002220393A - Manufacturing method for tetra tertiary alkoxysilane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture Si(OtBu)4 by reacting intermediate raw materials of Si(OtBu)3Cl or Si(OtBu)2Cl2 under mild conditions such as temperature less than 200 deg.C and atmospheric pressure without using an autoclave as a reactor, and to manufacture Si(OtAm)4 as well. SOLUTION: K(OtBu) used as a reaction agent is reacted with Si(OtBu)3Cl or Si(OtBu)2Cl2 in xylene solvent at 150 deg.C for 7 hours, and the reactant is filtered and distilled. Thereby, Si(OtBu)4 with high purity is obtained at yield of 58%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing tetra-tertiary alkoxysilane suitable as a raw material for forming a silica-containing oxide film by a chemical vapor deposition (CVD) method.

[0002]

2. Description of the Related Art In the manufacture of semiconductor devices, an alkoxysilane raw material for forming an SiO ₂ -containing film by a CVD method is mainly tetraethoxysilane Si (OC ₂ H ₅ ).
₄ is used. However, when used in combination with other metal tertiary alkoxides, it is desirable that the Si source be tetratertiary alkoxysilane to prevent the exchange of alkoxy groups. In addition, since the thermal decomposition temperature of tetraethoxysilane is high, when it is desired to perform thermal decomposition at a lower temperature, tetratertiary alkoxysilane is preferable. The present inventors have disclosed in Japanese Patent Application No. 2000-2722.
No. 83 discloses a mixture of Zr (OtBu) ₄ and Si (OtBu) ₄ as a CVD raw material composition for producing a zirconia-silica-containing oxide film useful as a gate insulating film (OtBu. tertiary butoxy group OC represents a _{(CH 3) 3).}

[0003] However, the production of Si (OtBu) ₄
When iCl ₄ is used as a raw material, OtBu is bulky, so that it is difficult to replace it with the fourth Cl, and there is a problem that strict reaction conditions are required. M. G. FIG. Voronkov et al. Zh
ur. Obshchei Khim. Vol. 26,3
072 (1956) (Abstract Chem. Ab. Vol. 5)
1,8643) is composed of Si (OtBu) ₃ Cl and Na (O
tBu) and a toluene solvent were charged into a steel autoclave, heated at 220 ° C. for 18 hours, and the product was distilled to obtain crude S
i (OtBu) ₄ was obtained in a yield of 47% and then recrystallized from ethanol to give pure Si (OtBu) with a melting point of 51.5 ° C.
I got ₄ . Uses an autoclave and has strict conditions. The intermediate material Si (OtBu) ₃ Cl is obtained by heating and reacting tBuOH, pyridine and SiCl ₄ in a toluene solvent, filtering, and then distilling.

[0004] H. Breederveld et al. Rec. t
rv. chim. vol. 73, 871 (1954)
(Abstract Chem. Ab. Vol. 49, 8792)
Using highly reactive SiBr ₄ as a raw material, Na (OtB
u) to obtain Si (OtBu) ₃ Br, which is heated in a sealed tube at 220 ° C. for 10 hours, filtered, and distilled to obtain Si (OtBu) ₄ . Again, a strict condition is used to insert the fourth OtBu. As mentioned above, in any case during autoclave,
Strict conditions of 10 to 18 hours at 20 ° C. were required.

[0005]

SUMMARY OF THE INVENTION Si (OtBu) ₃ C
l or Si (OtBu) ₂ Cl ₂ as an intermediate material,
Do not use an autoclave in the reactor,
The reaction is carried out under a mild condition of 0 ° C. or less, and Si (OtBu)
₄ to provide a method of manufacturing the same. Similarly, S
It is to provide a method for producing i (OtAm) _4, where OtAm represents a tertiary amyloxy group OC (CH ₃ ) ₂ C ₂ H ₅ .

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a Si (OR)
The _n Cl _4-n in a method for producing a Si _{(OR) 4} as a raw material, a process for preparing tetra-tertiary alkoxysilane, which comprises using a K (OR) (potassium tertiary alkoxide) as a reactant. Where R
Is C (CH ₃ ) ₃ or C (CH ₃ ) ₂ (C ₂ H ₅ )
And n represents 3 or 2. The present invention relates to Si (OR) _n
A process for producing tetratertiary alkoxysilane, wherein the reaction between Cl _4-n and K (OR) is performed in an inert organic solvent at 130 to 170 ° C. under atmospheric pressure.
The present invention relates to K (O) for Si (OR) _n Cl _4-n .
The charge amount of R) was changed to 1.1 of (4-n), which is the equivalent of Cl.
A method for producing tetratertiary alkoxysilane, characterized in that the amount is up to 1.5 times. The present invention relates to Si (O
R) _n Cl _4-n is a method for producing tetratertiary alkoxysilane, wherein the inert organic solvent used in the reaction of K (OR) has a boiling point of 130 to 170 ° C. The present invention relates to Si (OR) _n Cl _4-n and K (OR)
And xylene is the inert organic solvent used in the reaction with the tertiary alkoxysilane. The present invention relates to Si (OR) _n Cl _4-n and K
A method for producing tetratertiary alkoxysilane, comprising reacting with (OR), separating KCl crystals by-produced by filtration, and collecting the crystals by distillation under reduced pressure. In the present invention, the reaction of Si (OR) _n Cl _4-n with K (OR), KCl crystals by-produced are separated by filtration, and then, the Si (OR) ₄ obtained by vacuum distillation recovery is obtained. Wherein the Cl content is 10 ppm or less and the K content is 1 ppm or less.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The case of Si (OtBu) ₄ will be described below, but the same applies to Si (OtAm) ₄ . The intermediate material used in the present invention is Si (OtBu) ₃
Cl or Si (OtBu) ₃ Cl and Si (OtBu)
It is a mixture of ₂ Cl ₂ . These are described in the M.D. G. FIG. V
It can be obtained by the method of Oronkov et al. That is, t
S in a toluene solution of 4 mol of BuOH and 4 mol of pyridine
After 1 mol of iCl _{4 was} added dropwise and reacted for 10 hours by heating in a water bath, the mixture was filtered and distilled to obtain Si (OtBu) ₃ Cl.
Obtained in 4% yield. Si _(OtBu) 3 the boiling point at atmospheric pressure of Cl is 202-203 ° C.. According to the study results of the present inventors, if the reaction temperature and time are set to mild conditions,
A mixture of Si (OtBu) ₃ Cl and Si (OtBu) ₂ Cl ₂ can be sufficiently used as an intermediate material in the present invention. Si (OtBu) ₃ Cl and Si (OtBu) ₂ Cl
_Since the ratio of ₂ can be easily analyzed by gas chromatography, a preferable amount of charged K (OtBu) can be calculated.

[0008] K (OtBu) used in the present invention is tB
It is easily obtained by introducing metal potassium K into uOH at room temperature to cause a reaction, and then distilling off unreacted raw material tBuOH under reduced pressure. Since K is much more active than Na, the reaction time may be short. In addition, K (OtBu) is commercially available and can be used.

The reaction formula used in the present invention is as follows.

[0010]

Embedded image

K for Si (OtBu) _n Cl _4-n
The charged amount of (OtBu) is the equivalent of Cl (4-n).
It is preferable that the amount is 1.1 to 1.5 times the amount. When the ratio is 1.1 times or less, Cl is likely to remain, which is not preferable. When the ratio is 1.5 times or more, there is no advantage of using it frequently.

The reaction is carried out in an inert organic solvent at 130 to 170
C. for 2-10 hours. Solvent and K (OtBu) in reactor
, And dispersed by stirring. At room temperature, oily Si (Ot
When (Bu) _n Cl _4-n is dropped, first, Si (Ot
Bu) ₂ Cl ₂ reacts and the exothermic reaction causes a liquid temperature of 80 ° C.
Rise to near. The full-scale reaction of Si (OtBu) ₃ Cl occurs rapidly around 150 ° C. In order to control the reaction temperature, it is preferable that the solvent be refluxed to remove heat. S
Since the boiling point of i (OtBu) ₄ at atmospheric pressure is 222 ° C., in order to separate the solvent by distillation, the boiling point of the solvent must be 1
Those having a temperature of 70 ° C. or lower are preferred. Also, under atmospheric pressure, 130
Since the reaction conditions are required to be higher than ℃, it is preferable that the solvent is refluxed to remove heat and control the reaction temperature.
Those having a temperature of 30 ° C. or higher are preferred. Therefore, the solvent used preferably has a boiling point of 130 to 170 ° C. A preferred inert organic solvent is xylene. For xylene,
The reaction temperature can be controlled to around 150 ° C. by using the reflux. As xylene, any of ortho-xylene (boiling point: 144.4 ° C.), meta-xylene (139.1 ° C.), para-xylene (138.4 ° C.), or a mixture thereof may be used.

[0013] Si (O
tBu) ₄ can be produced, but the reaction at 130 to 170 ° C. may be performed in an autoclave, focusing on the reduction of time and the ease of solvent separation. In that case, toluene or the like can be used as a solvent. Also in this case, by using K (OtBu), the reaction conditions are milder than Na (OtBu), and the yield is improved.

Si (OtBu) ₃ Cl and K (OtBu)
After that, KCl crystals by-produced were separated by filtration, and then the solvent was removed as a first distillation by vacuum distillation to remove SiCl.
(OtBu) ₄ is obtained as the main fraction. Vacuum distillation is 5-1
Perform at 00 Torr. As an example, Si at 15 Torr
The distillation temperature of (OtBu) ₄ is around 105 ° C. The Cl content in the Si (OtBu) ₄ obtained through the above process can be very small, 10 ppm or less. K (OtB
Since u) has a very low sublimation pressure, it is removed by distillation,
The K content can be reduced to 1 ppm or less. The fact that Cl and K are small is very preferable as a raw material for manufacturing semiconductor devices. In distillation under atmospheric pressure, the heating temperature of the kettle becomes too high at 250 ° C., and thermal decomposition of a part of Si (OtBu) ₄ occurs, and the generated tBuOH and the like are mixed into the main fraction.

[0015]

EXAMPLE Production of Si (OtBu) _{4 5} equipped with a reflux condenser, thermometer and stirrer
741g of dehydrated tBuOH (10.0mo
l), 791 g (10.0 mol) of dehydrated pyridine and 0.7 L of toluene were charged and stirred with 0.1 mL of dehydrated toluene.
425 g (2.5 mol) of SiCl ₄ diluted with 5 L
Was added dropwise at room temperature. Then, the temperature was raised and kept at 75 ° C. for 4 hours. After cooling, the mixture was filtered and the solvent was distilled off under reduced pressure. Then 15T
Distillation was performed at orr, and 400 g of a 50-90 ° C distillate was recovered. This fraction was analyzed by gas chromatography to find out that 52% of Si (OtBu) ₂ Cl ₂ and Si (OtBu)
₃ Cl 48% (1.52 m as Si)
ol, 61% yield).

Then, 0.35 L of xylene was placed in a 3 L flask equipped with a reflux condenser, a thermometer and a stirrer.
And K (OtBu) (274 g, 2.44 mol) were charged, stirred, and dispersed. Next, 300 g of the recovered fraction
(1.14 mol of Si, 1.77 mol of Cl)
When K / Cl = 1.38 was added dropwise slowly from room temperature, an exothermic reaction occurred and the liquid temperature rose to about 80 ° C. At this point, Si (OtBu) ₂ Cl ₂ is converted to S
i (OtBu) ₃ Cl. Then, when the temperature was increased by heating, a violent exothermic reaction occurred from about 130 ° C., reflux occurred, and the liquid temperature was controlled at about 150 ° C. After stirring and holding at 150 ° C. for 7 hours, the mixture was cooled and filtered.

Next, the filtrate is charged into a vacuum distillation apparatus, and
Distillation was performed at 5 Torr. Xylene was mainly recovered at 40 to 80 ° C as the first distillation. Then, it is cooled with hot water so that Si (OtBu) ₄ does not solidify, and 210 g (0.66 mo) of main fraction Si (OtBu) ₄ at a distillation temperature of around 105 ° C.
1) was obtained. The yield based on Si in the subsequent step was 58%. Melting point 51 [deg.] C. As a result of measurement of this main fraction with a toluene solution, the purity by gas chromatography was 99.5%. FIG. 1 shows the measurement results. As a result of impurity analysis, C
l <10 ppm, K <1 ppm, Na <1 ppm, Fe
<1 ppm, Ca <1 ppm, and all other metal elements were also 1 ppm or less, indicating high purity.

[0018]

By using Si (OtBu) ₃ Cl as an intermediate material and using K (OtBu) as a reactant, Si (OtBu) can be reacted under atmospheric pressure under mild conditions at 150 ° C.
u) ₄ can be manufactured. No autoclave is required as a reactor. The obtained Si (OtBu) ₄ is Cl,
Since the content of impurities such as K is small, it can be used as a raw material for manufacturing semiconductor devices.

[Brief description of the drawings]

FIG. 1 G of toluene solution of main fraction Si (OtBu) ₄
It is a figure showing the measurement result by C-FID.

Claims (7)

[Claims] 1. A method using S (OR) _n Cl _4-n as a raw material
In the method for producing i (OR) ₄ , K is used as a reactant.
A method for producing tetratertiary alkoxysilane, comprising using (OR). Here, R represents C (CH ₃ ) ₃ or C (CH ₃ ) ₂ (C ₂ H ₅ ), and n represents 3 or 2. 2. The method according to claim 1, wherein the reaction between Si (OR) _n Cl _4-n and K (OR) is carried out in an inert organic solvent at 130 to 170 ° C. under atmospheric pressure. Method for producing tetratertiary alkoxysilane. 3. The tetratertiary alkoxy according to claim 2, wherein the amount of K (OR) charged is 1.1 to 1.5 times the equivalent of (4-n), which is the equivalent of Cl. Production method of silane. 4. The process for producing tetratertiary alkoxysilane according to claim 2, wherein the inert organic solvent has a boiling point of 130 to 170 ° C. 5. The method according to claim 2, wherein the inert organic solvent is xylene. 6. After reacting Si (OR) _n Cl _4-n with K (OR), KCl crystals by-produced are separated by filtration.
2. The method according to claim 1, wherein the solution is recovered by distillation under reduced pressure.
2. The method for producing a tetratertiary alkoxysilane according to 2, 3, 4, or 5. 7. The obtained Si (OR) _{4 has} a Cl content of 10%.
7. The method for producing a tetratertiary alkoxysilane according to claim 6, wherein the K content is 1 ppm or less.