Organotitanium precursors and manufacturing method thereof

Abstract

Disclosed are an organotitanium precursor and a method for manufacturing the same. The organotitanium precursor of the present invention has a structure in which titanium ion having a valence of +4, glycol having a valence of −2, &bgr;-ketoester having a valence of −1 are reacted in a molar ratio of 1:1:2, and thereby coordination sites of the titanium are saturated. According to the invention, volatility of the precursor is enhanced. Also, since the precursor is separated in the form of a white powder, it is easy to deal the precursor. Further, the precursor of the invention allows a superior deposition rate even at a temperature of 470° C. or less, so that it is possible to economically manufacture titanium dioxide thin film which is applicable to BST or PZT system.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to organotitanium precursors and manufacturing method thereof, and more particularly, to organotitanium precursors which are used as source materials in metal-organic chemical vapor deposition and manufacturing method thereof.

[0003] 2. Description of the Related Art

[0004] Volatile organotitanium precursors are generally used as source materials for the fabrication of thin films of ferroelectrics and paraelectrics such as PZT and BST by metal-organic chemical vapor deposition (MOCVD).

[0005] The prevalent titanium tetraalkoxide precusor is so sensitive to air and moisture that it is easily decomposed and oligomerized. Thus, it has a drawback in that the volatile property thereof is changed.

[0006] Accordingly, in order to overcome this drawback, there was developed Ti (Opri)2 (tmhd)2 (Here, Opri is isopropoixde, and tmhd is 2,2,6,6-tetramethyl heptanedionate) in which two diketone compounds are substituted for two alkoxides. However, because Ti (Opri)2(tmhd)2 is also decomposed and oligomerized by a disproportionation reaction during its use, such a drawback in which volatile property is changed has not been resolved. In addition, it has the following drawbacks in that its decomposition reaction proceeds complicatedly in two steps or more, hump and haziness appear on the surface of the deposited thin film, and so the surface is not smooth and has a protrusion.

[0007] Meanwhile, in the year 1998, Japanese Asahi Denka company developed Ti(MPD) (tmhd)2 (here, MPD is 2-methyl-2,4-pentanediolate). Compared with Ti(Opri)2 (tmhd)2, the decomposition reaction of Ti(MPD) (tmhd)2 is simple and the drawback, in that it is thermally decomposed and oligomerized during its use, has been resolved.

[0008] However, in case of depositing a titanium dioxide thin film using Ti(MPD) (tmhd)2, there is a need that the temperature of the substrate should be maintained at 480° C. or higher in order to maintain a sufficient deposition rate allowing a deposition of a thin film having a constant titanium composition ratio. So, if Ti(MPD) (tmhd)2 is used together with traditional DRAM technologies allowing a temperature application of 470° C. at most, the deposited thin film is Ti-deficient in the BST film.

[0009] Also, if Ti(MPD) (tmhd)2 is used in order to manufacture a thin film having a composition ratio of barium and strontium to titanium, 1:1, since the deposition rate of this titanium precursor is slow, there should be maintained a composition ratio of barium and strontium to titanium precursor, 1:8 in a mixed solution of Ti(MPD) (tmhd)2, barium, and strontium precursors. Accordingly, the titanium precursor is wasted to a serious degree. Further, Ti(MPD)(tmhd)2 precursor is a brown colored glass-like solid, and is sold in the form of solution dissolved in a solvent. So, it is not easy to separate the pure precursor and deal with it.

SUMMARY OF THE INVENTION

[0010] Therefore, it is an object of the present invention to provide an organotitanium precursor having a superior volatility and a high deposition rate at a low temperature and providing an easy dealing.

[0011] It is another object to provide a method for manufacturing an organotitanium precursor capable of accomplishing the above object.

[0012] To achieve the aforementioned objects, the organotitanium precursor according to the present invention has the following chemical formula 1: 1

[0013] wherein R1 and R2 are selected from a group consisting of n- or branched-chain alkyl group each having 1-8 carbon atoms, cycloalkyl group, phenyl group, and benzyl group, and R3 is n- or branched-chain alkylene group composed of 2-13 carbon atoms.

[0014] To accomplish another object of the present invention, there is provided a method for manufacturing an organotitanium precursor. The method comprises: a first step of preparing a titanium tetraalkoxide expressed by Ti(OR)4 or a material containing the titanium tetraalkoxide; a second step of adding a glycol expressed by a formula 2 to the titanium tetraalkoxide or the material, and reacting the glycol with the titanium tetraalkoxide or the material to form a reaction intermediate; a third step of adding a &bgr;-ketoester expressed by a formula 3 to the reaction intermediate, and reacting the &bgr;-ketoester with the reaction intermediate to form a reaction product; and a fourth step of removing a unnecessary by-product from the reaction product, and adding a solvent containing an alcohol component to the unnecessary by-product-removed reaction product to yield white precipitate,

[0015] Formula 2:

HO-R3-OH  

[0016] 2

[0017] wherein R is an alkyl group in which the number of n- or branched-chain carbon atoms is 1-4, R1 and R2 are selected from a group consisting of n- or branched-chain alkyl group each having 1-8 carbon atoms, cycloalkyl group, phenyl group, and benzyl group, and R3 is n- or branched-chain alkylene group composed of 2-13 carbon atoms.

[0018] According to another aspect of the present invention, there is provided a method for manufacturing an organotitanium precursor. The method comprising: a first step of preparing a titanium tetraalkoxide expressed by Ti(OR)4 or a material containing the titanium tetraalkoxide; a second step of adding a &bgr;-ketoester expressed by the formula 3 to the titanium tetraalkoxide or the material, and reacting the &bgr;-ketoester with the titanium tetraalkoxide or the material to form a reaction intermediate; a third step of adding a glycol expressed by the formula 2 to the reaction intermediate, and reacting the glycol with the reaction intermediate to form a reaction product; and a fourth step of removing a unnecessary by-product from the reaction product, and adding a solvent containing an alcohol component to the unnecessary by-product-removed reaction product to yield white precipitate.

[0019] According to further another aspect of the present invention, there is provided a method for manufacturing an organotitanium precursor. The method comprises: a first step of preparing a titanium tetraalkoxide expressed by Ti(OR)4 or a material containing the titanium tetraalkoxide; a second step of adding a glycol expressed by the formula 2 and a &bgr;-ketoester expressed by the formula 3 to the titanium tetraalkoxide or the material, and reacting the &bgr;-ketoester and the glycol with the titanium tetraalkoxide or the material to form a reaction product; and a third step of removing a unnecessary by-product from the reaction product of the second step, and adding a solvent containing an alcohol component to the unnecessary by-product-removed reaction product to yield white precipitate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above objects and other advantages of the present invention will become more apparent by describing in detail preferred embodiments thereof with reference to the attached drawings in which:

[0021] FIG. 1A through FIG. 4 are graphs for showing results of an IR analysis or a TGA analysis of respective organotitanium precursors manufactured in accordance with first to fourth embodiments of the present invention;

[0022] FIG. 5 is a graph showing a comparison result of the deposition rates when titanium dioxide thin films are respectively deposited by a metal-organic chemical vapor deposition using an organometallic precursor of the present invention and a conventional organometallic precursor; and

[0023] FIGS. 6A and 6B are SEM photographs respectively showing a plain-view surface shape and a cross-section of a thin film when the thin film is deposited using the organotitanium precursor in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Now, preferred embodiments of the present invention will be described in detail with reference to the annexed drawings.

[0025] In order to form an organotitanium precursor which is stable in the atmosphere and is easy in the dealing thereof, there should be a satisfied structure in which an alkoxide having a valence of −1 does not exist and six coordination sites of titanium are saturated. Also, in order for the organotitanium precursor to have a superior volatility, not symmetric but asymmetric organic ligand should be preferable.

[0026] Accordingly, the present invention uses a &bgr;-ketoester capable of breaking the symmetry to enhance the volatility, and reacts titanium tetraalkoxide with glycol having a valence of −2 and &bgr;-ketoester having a valence of −1 in molar ratio of 1:1:2, thereby manufacturing an organotitanium precursor having the structural formula 1 in which coordination sites of titanium are saturated.

[0027] In the chemical formulas 1-3, as a n- or branched-chain alkyl group expressed by R1 and R2 and having 1-8 carbon atoms, there are methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, t-butyl, n-pentyl, 2-methylbutyl, 3-methylbutyl, neopentyl, n-hexyl, 2-methylpentyl, 3-methylpentyl, isoheptyl, isooctyl, 2-methylheptyl, 3-methylheptyl, 2-ethylhexyl, etc., and as a cycloalkyl group, there is a cyclohexyl group.

[0028] Also, R3 is a n- or branched-chain alkylene group and is given by glycol (diol) As examples of the glycol, there are 1,2-ethanediol, 1,3-propanediol, 1,3-dimethyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-2-ethyl -1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 1-methyl-1,3-propanediol, 2-methyl -1,3-propanediol, etc. Among the aforementioned examples, 1,3-propanediol and alkyl derivatives thereof are especially preferred because they further enhance effects of the present invention.

[0029] Meanwhile, in a method for manufacturing an organotitanium precursor in accordance with the present invention, a titanium tetraalkoxide without any solvent may be reacted with the glycol and &bgr;-ketoester, but it is more desirable that the titanium tetraalkoxide is dissolved in aliphatic or aromatic hydrocarbon solvent to form a solution system, and then the solution is reacted with the glycol and the &bgr;-ketoester. At this time, as the solvent, alcohol group or amine group that reacts with the titanium tetraalkoxide is not preferred. Further, in order to effectively remove the solvent used to dissolve the titanium tetaalkoxide and a unnecessary by-product generated during manufacturing the organotitanium precursor, it is desirable to choose a solvent which can make an azeotropic mixture with the byproduct at a low boiling point.

[0030] Hereinafter, there is described in detail a method for manufacturing the organotitanium precursor expressed by the formula 1. Embodiments 1-6 to be described are merely given for the purpose of description of the manufacturing method of the organotitanium precursor in accordance with the invention. Therefore, the invention is not limited only to the embodiments 1-6.

[0031] Embodiments 1-4 manufacture organotitanium precursors by adding different kinds of glycols and &bgr;-ketoesters to a titanium tetraalkoxide-dissolved solution, and reacting them.

[0032] Embodiment 5 manufactures an organotitanium precursor by using the same glycol and &bgr;-ketoester as those of the embodiment 1, in which the glycol is first added to the titanium tetraalkoxide-dissolved solution to react them, and then &bgr;-ketoester is added to react them.

[0033] Embodiment 6 manufactures an organotitanium precursor by using the same glycol and &bgr;-ketoester as those of the embodiment 1, in which the &bgr;-ketoester is first added to the titanium tetraalkoxide-dissolved solution to react them, and then the glycol is added to react them.

[0034] Embodiment 1

[0035] First, 4.55 g (0.16 mole) of titanium tetraisopropoxide is dissolved in 16 ml of dehydrated and distilled hexane under nitrogen atmosphere.

[0036] Next, 5.06 g (0.032 mole) of methyl 2,2-dimethyl-3-oxopentanoate, and 1.89 g (0.016 mole) of 2-methyl-2,4-pentanediol are added to the titanium tetraisopropoxide -dissolved solution, and they are refluxed for one hour.

[0037] After that, a solution containing a reaction product of the titanium tetraisopropoxide, the methyl 2,2-dimethyl-3-oxopentanoate, and the 2-methyl-2,4-pentanediol is distilled to remove the hexane solvent and a by-product, i.e., isopropanol, and then dehydrated and distilled methanol is added to the hexane solvent- and the by-product-removed solution, and thereby white solid is obtained. This solid is filtered, is washed with cold methanol, and is dried for three hours in a vacuum state to thereby yield 3.8 g of an organotitanium precursor of Ti(MPD) (MDOP)2 (abbreviation) expressed by the following chemical formula 4: 3

[0038] Embodiment 2

[0039] First, 4.55 g (0.16 mole) of titanium tetraisopropoxide is dissolved in 16 ml of dehydrated and distilled hexane under nitrogen atmosphere.

[0040] Next, 5.06 g (0.032 mole) of methyl 2,2-dimethyl-3-oxopentanoate, and 1.67 g (0.016 mole) of 2,4-pentanediol are added to the titanium tetraisopropoxide-dissolved solution, and they are refluxed for one hour.

[0041] After that, a solution containing a reaction product of the titanium tetraisopropoxide, the methyl 2,2-dimethyl-3-oxopentanoate, and the 2,4-pentanediol is distilled to remove the hexane solvent and the isopropanol, and then dehydrated and distilled methanol is added to the hexane solvent- and the isopropanol-removed solution, and thereby white solid is obtained. This solid is filtered, is washed with cold methanol, and is dried for three hours in a vacuum state to thereby yield 3.8 g of an organotitanium precursor of Ti(PD) (MDOP)2 (abbreviation) expressed by the following chemical formula 5: 4

[0042] Embodiment 3

[0043] First, 4.55 g (0.16 mole) of titanium tetraisopropoxide is dissolved in 16 ml of dehydrated and distilled hexane under nitrogen atmosphere.

[0044] Next, 5.06 g (0.032 mole) of methyl 2,2-dimethyl-3-oxopentanoate, and 1.67 g (0.016 mole) of neopentylglycol are added to the titanium tetraisopropoxide-dissolved solution, and they are refluxed for one hour.

[0045] After that, a solution containing a reaction product of the titanium tetraisopropoxide, the methyl 2,2-dimethyl-3-oxopentanoate, and the neopentylglycol is distilled to remove the hexane solvent and the isopropanol, and dehydrated and distilled methanol is added to the hexane solvent- and the isopropanol-removed solution, and thereby white solid is obtained. This solid is filtered, washed with cold methanol, and is dried for three hours in a vacuum state to thereby yield 3.56 g of an organotitanium precursor of Ti(NPG) (MDOP)2 (abbreviation) expressed by the following chemical formula 6: 5

[0046] Embodiment 4

[0047] First, 4.55 g (0.16 mole) of titanium tetraisopropoxide is dissolved in 16 ml of dehydrated and distilled hexane under nitrogen atmosphere.

[0048] Next, 1.89 g (0.016 mole) of 2-methyl-2,4-pentanediol and 4.16 g (0.032 mole) of ethyl acetoacetate are added to the titanium tetraisopropoxide-dissolved solution, and they are refluxed for one hour.

[0049] After that, a solution containing a reaction product of the titanium tetraisopropoxide, the ethyl acetoacetate, and the 2-methyl-2,4-pentanediol is distilled to remove the hexane solvent and the isopropanol, and dehydrated and distilled methanol is added to the hexane solvent- and the isopropanol-removed solution, and thereby white solid is obtained. This solid is filtered, is washed with cold methanol, and is dried for three hours in a vacuum state to thereby yield 2.06 g of an organotitanium precursor of Ti(MPD)(ETAC)2 (abbreviation) expressed by the following chemical formula 7: 6

[0050] FIG. 1A through FIG. 4 are graphs for showing results of an IR analysis or a TGA analysis of respective organotitanium precursors manufactured in accordance with the first to fourth embodiments of the present invention. Specifically, FIG. 1A is a graph for showing an IR analysis result of the organotitanium precursor of the first embodiment, FIG. 1B is a graph for showing a TGA analysis result of the organotitanium precursor of the first embodiment, FIG. 2 is a graph for showing an IR analysis result of the organotitanium precursor of the second embodiment, FIG. 3 is a graph for showing an IR analysis result of the organotitanium precursor of the third embodiment, and FIG. 4 is a graph for showing an IR analysis result of the organotitanium precursor of the fourth embodiment.

[0051] The below table 1 is the physical properties of the products manufactured from embodiment 1 through 4. 1 TABLE 1 Weight Decrease- Sublimation Calculated Measured Melting starting Condition molecular molecular point point Temp. Pressure Item weight weight (° C.) Shape (° C.) (° C.) (mmHg) Em1 478 478 130-134 White 183 140-150 0.03 powder Em2 464 464 93-97 White 125 110-120 0.02 powder Em3 464 464 180, White Decomposition decomposition powder start at 180° C. Em4 422 422 85-88 White 80-90 0.05 powder

[0052] Embodiment 5

[0053] First, 4.55 g (0.16 mole) of titanium tetraisopropoxide is dissolved in 16 ml of dehydrated and distilled hexane under nitrogen atmosphere.

[0054] Next, 1.89 g (0.016 mole) of 2-methyl-2,4-pentanediol is added to the titanium tetraisopropoxide-dissolved solution, and they are stirred for one hour to thereby react the titanium tetraisopropoxide with the 2-methyl-2,4-pentanediol.

[0055] After that, 5.06 g (0.032 mole) of methyl 2,2-dimethyl -3-oxopentanoate is added to a solution containing a reaction intermediate of the titanium tetraisopropoxide, and the 2-methyl-2,4-pentanediol, and they are refluxed for one hour to thereby react the solution containing the reaction intermediate of the titanium tetraisopropoxide, and the 2-methyl-2,4-pentanediol with the methyl 2,2-dimethyl-3-oxopentanoate.

[0056] Thereafter, the solution containing a reaction product of the titanium tetraisopropoxide, the 2-methyl-2,4-pentanediol, and the methyl 2,2-dimethyl-3-oxopentanoate is distilled to remove the hexane solvent and the isopropanol, and dehydrated and distilled methanol is added to the hexane solvent- and the isopropanol-removed solution, and thereby white solid is obtained. This solid is filtered, washed with cold methanol, and dried for three hours in a vacuum state to thereby yield 3.11 g of the organotitanium precursor of Ti(MPD)(MDOP)2 like the first embodiment.

[0057] Embodiment 6

[0058] First, 4.55 g (0.16 mole) of titanium tetraisopropoxide is dissolved in 16 ml of dehydrated and distilled hexane under nitrogen atmosphere.

[0059] Next, 5.06 g (0.032 mole) of methyl 2,2-dimethyl-3-oxopentanoate is added to the titanium tetraisopropoxide -dissolved solution, and they are stirred for one hour to thereby react the titanium tetraisopropoxide with the methyl 2,2-dimethyl-3-oxopentanoate.

[0060] After that, 1.89 g (0.016 mole) of 2-methyl-2,4-pentandiol is added to a solution containing a reaction intermediate of the titanium tetraisopropoxide, and the methyl 2,2-dimethyl-3-oxopentanoate, and they are refluxed for one hour to thereby react the solution containing the reaction intermediate of the titanium tetraisopropoxide, and the methyl 2,2-dimethyl-3-oxopentanoate with the 2-methyl -2,4-pentandiol.

[0061] Thereafter, the solution containing a reaction product of the titanium tetraisopropoxide, the methyl 2,2-dimethyl-3-oxopentanoate, and the 2-methyl-2,4-pentandiol is distilled to remove the hexane solvent and the isopropanol, and dehydrated and distilled methanol is added to the hexane solvent- and the isopropanol-removed solution, and thereby white solid is obtained. This solid is filtered, washed with cold methanol, and dried for three hours in a vacuum state to thereby yield 3.13 g of an organotitanium precursor of Ti(MPD)(MDOP)2 like the first embodiment.

COMPARATIVE EXAMPLE 1

[0062] TiO2 thin films were deposited by a MOCVD method using Ti(MPD) (MDOP)2 and the conventional Ti(MPD) (tmhd)2 as the source materials.

[0063] At this time, common conditions for the deposition of the thin films, were a use of a direct substrate heating type CVD apparatus having a direct liquid injection system, and a use of a silicone substrate on which a SiO2 thin film, a Ti thin film, and a Pt thin film are sequentially deposited. Further, O2 was used as the reaction gas, Ar was used as the carrier gas, and the deposition time was 30 minutes.

[0064] Meanwhile, Ti(MPD)(tmhd)2 was dissolved in n -butylacetate, while Ti(MPD) (MDOP)2 was dissolved in toluene. At this time, the concentration of titanium precursors in respective solutions was 0.08 M. The temperature of a flash vaporizer was maintained at 260° C.

[0065] FIG. 5 is a graph showing a comparison result of the deposition rates when TiO2 thin films are respectively deposited under the recipe of the comparative example 1. In FIG. 5, a reference symbol “A” indicates a case that the organotitanium precursor in accordance with the present invention was used, and a reference symbol “B” indicates a case that a conventional organotitanium precursor was used.

[0066] The below table 2 shows thin film thickness as deposited depending on the substrate temperature, and the thickness was obtained by analyzing SEM photographs of the deposited thin films. 2 TABLE 2 Organotitanium Substrate Precursor temperature Thickness Ti (MPD) (tmhd)2 425° C.   800 Å 450° C. 1,300 Å Ti (MPD) (MDOP)2 425° C. 2,625 Å 450° C. 3,938 Å

[0067] Referring to FIG. 5 and table 2, it is apparent that the case of the present invention in which TiO2 thin film is deposited using Ti(MPD) (MDOP)2 has a much higher deposition rate than the conventional case in which TiO2 thin film is deposited using Ti(MPD) (tmhd)2, and also the case of the present invention is much thicker in the deposited film thickness than the conventional case.

[0068] FIG. 6A is a SEM photograph showing a plain-view surface shape of a thin film when the thin film is deposited using Ti(MPD) (MDOP)2 as the organotitanium precursor at a deposition temperature of 425° C. to a thickness of 2,625 Å under the deposition condition of the comparative example 1, and FIG. 6B is a SEM photograph showing a cross-section of the deposited thin film.

[0069] Referring to FIGS. 6A and 6B, it is known that the TiO2 thin film deposited by using Ti(MPD) (MDOP)2 of the present invention is very dense and smooth.

[0070] According to the organotitanium precursor and manufacturing method thereof of the present invention, as described above, the use of &bgr;-ketoester capable of breaking the symmetry structure enhances the volatility of the precursor. Also, titanium tetraalkoxide, glycol having a valence of −2, and &bgr;-ketoester having a valence of −1 are reacted in a molar ratio of 1:1:2, and thereby the precursor has a structure in which coordination sites of the titanium are saturated, so that a chemically stable organotitanium precursor is obtained. Further, during its manufacturing, since the precursor is separated in the form of a white powder, it is easy to deal it.

[0071] Furthermore, when depositing the thin film using the organotitanium precursor of the present invention, the thin film has a superior deposition rate even at a temperature of 470° C. or less, so that it is possible to economically manufacture the titanium dioxide thin film which is applicable to BST system.

[0072] While the present invention has been described in detail, it should be understood that various changes, substitutions and alterations could be made hereto without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. An organotitanium precursor has the following structural formula:

7

wherein R1 and R2 are selected from a group consisting of n- or branched-chain alkyl group each having 1-8 carbon atoms, cycloalkyl group, phenyl group, and benzyl group, and R3 is n- or branched-chain alkylene group composed of 2-13 carbon atoms.

2. A method for manufacturing an organotitanium precursor, the method comprising:

a first step of preparing a titanium tetraalkoxide expressed by Ti(OR)4 or a material containing the titanium tetraalkoxide;

a second step of adding a glycol expressed by a formula 2 to the titanium tetraalkoxide or the material, and reacting the glycol with the titanium tetraalkoxide or the material to form a reaction intermediate;

a third step of adding a 0-ketoester expressed by a formula 3 to the reaction intermediate, and reacting the &bgr;-ketoester with the reaction intermediate to form a reaction product; and

a fourth step of removing a unnecessary by-product from the reaction product, and adding a solvent containing an alcohol component to the unnecessary by-product-removed reaction product, and thereby obtaining white solid,

Formula 2:

8

wherein R is an alkyl group in which the number of n- or branched-chain carbon atoms is 1-4, R1 and R2 are selected from a group consisting of n- or branched-chain alkyl group each having 1-8 carbon atoms, cycloalkyl group, phenyl group, and benzyl group, and R3 is n- or branched -chain alkylene group composed of 2-13 carbon atoms.

3. The method of claim 2, wherein the material containing the titanium tetraalkoxide is a solution which is formed by adding an aliphatic hydrocarbon or aromatic hydrocarbon series solvent to the titanium tetraalkoxide, and said the fourth step further comprises a step of removing the solvent.

4. The method of claim 2 or 3, wherein the organotitanium precursor contains titanium, the glycol, and the &bgr;-ketoester having a molar ratio of 1:1:2.

5. A method for manufacturing an organtitanium precursor, the method comprising:

a first step of preparing a titanium tetraalkoxide expressed by Ti(OR)4 or a material containing the titanium tetraalkoxide;

a second step of adding a &bgr;-ketoester expressed by a formula 4 to the titanium alkoxide or the material, and reacting the &bgr;-ketoester with the titanium alkoxide or the material to form a reaction intermediate;

a third step of adding a glycol expressed by a formula 5 to the reaction intermediate, and reacting the glycol with the reaction intermediate to form a reaction product; and

a fourth step of removing a unnecessary by-product from the reaction product, and adding a solvent containing an alcohol component to the unnecessary by-product-removed reaction product, and thereby obtaining white solid,

9

Formula 5:

HO-R3-OH

wherein R is an alkyl group in which the number of n- or branched-chain carbon atoms is 1-4, R1 and R2 are selected from a group consisting of n- or branched-chain alkyl group each having 1-8 carbon atoms, cycloalkyl group, phenyl group, and benzyl group, and R3 is n- or branched-chain alkylene group composed of 2-13 carbon atoms.

6. The method of claim 5, wherein the material containing the titanium tetraalkoxide is a solution which is formed by adding an aliphatic hydrocarbon or aromatic hydrocarbon series solvent to the titanium tetraalkoxide, and said the fourth step further comprises a step of removing the solvent.

7. The method of claim 5 or 6, wherein the organotitanium precursor contains titanium, the glycol, and the &bgr;-ketoester having a molar ratio of 1:1:2.

8. A method for manufacturing an organotitanium precursor, the method comprising:

a first step of preparing a titanium tetraalkoxide expressed by Ti(OR)4 or a material containing the titanium tetraalkoxide;

a second step of adding a glycol expressed by a formula 6 and a &bgr;-ketoester expressed by a formula 7 to the titanium alkoxide or the material, and reacting the &bgr;-ketoester and the glycol with the titanium alkoxide or the material to form a reaction product; and

a third step of removing a unnecessary by-product from the reaction product of the second step, and adding a solvent containing an alcohol component to the unnecessary by-product-removed second reaction product, and thereby obtaining white solid,

Formula 6:

HO-R3-OH

10

wherein R is an alkyl group in which the number of n- or branched-chain carbon atoms is 1-4, R1 and R2 are selected from a group consisting of n- or branched-chain alkyl group each having 1-8 carbon atoms, cycloalkyl group, phenyl group, and benzyl group, and R3 is n- or branched-chain alkylene group composed of 2-13 carbon atoms.

9. The method of claim 8, wherein the material containing the titanium tetraalkoxide is a solution which is formed by adding an aliphatic hydrocarbon or aromatic hydrocarbon series solvent to the titanium tetraalkoxide, and said the third step further comprises a step of removing the solvent.

10. The method of claim 8 or 9, wherein the organotitanium precursor contains titanium, the glycol, and the &bgr;-ketoester having a molar ratio of 1:1:2.