KR100634814B1 - Precursors of novel titanium oxide and preparation method thereof - Google Patents

Abstract

An organo-titanium compound is provided to be thermally stable and high volatile, thereby being used for high quality titanium oxide film. The organo-titanium compound is represented by the formula(1) and prepared by reacting an amido compound of titanium represented by the formula(2), Ti(NR'_2)4, with an alcohol compound represented by the formula(3), HOCR^1R^2R^3, or by reacting titanium chloride represented by the formula(4), TiCl4, with an alkali metal salt of alcohol represented by the formula(5), M'OCR^1R^2R^3. In the formulae(1) to (5), each R^1, R^2 and R^3 is independently C1-4 linear or branched alkyl, provided that not all the R^1, R^2 and R^3 are methyl, R' is methyl or ethyl, and M' is Li, Na or K.

Description

New Titanium Oxide Precursor and Method of Making the Substance {PRECURSORS OF NOVEL TITANIUM OXIDE AND PREPARATION METHOD THEREOF}

1 is a hydrogen atom nuclear magnetic resonance ( ¹ H NMR) spectrum of Ti (mp) ₄ prepared in Example 1 according to the present invention,

2 is a carbon atom nuclear magnetic resonance ( ¹³ C NMR) spectrum of Ti (mp) ₄ prepared in Example 1 according to the present invention,

3 is an infrared (IR) spectrum of Ti (mp) ₄ prepared in Example 1 according to the present invention,

4 is a thermal analysis (TG / DTA) graph of Ti (mp) ₄ prepared in Example 1 according to the present invention.

The present invention relates to novel organic titanium complexes useful as precursors of titanium oxides and methods for their preparation.

Titanium oxide (Titania, TiO ₂ ) is a material applied in many fields such as dielectric layers, antireflection coatings for optical devices, sensors, and photocatalysts. A method of growing these titania materials is metal organic chemical vapor deposition (MOCVD). This process has the advantages of a simple device, superior layer coverage compared to other techniques, easy control of components, and no difficulty in switching to mass production. Another method is atomic layer deposition (ALD), which has the advantage of allowing self-limiting reactions to grow thin films to a desired thickness. For the manufacture of thin films, it is essential to understand the development and characteristics of the precursors used in the process. The precursors for MOCVD and ALD should be sufficiently high vapor pressure below 200 ° C., thermally stable during heating to vaporize, and sufficiently stable to air and moisture during storage. As an additional requirement, it must be non-toxic or less toxic to itself or to decomposition products, to simplify the synthesis and to lower the cost of the raw materials.

As a precursor for producing titanium oxide, titanium alkoxide is known to be the best material and has been widely used until now. Among them, alkoxide compounds such as titanium tetraisopropoxide (Ti (O ⁱ Pr) ₄ ) are liquid, high vapor pressure, less sensitive to thin film deposition temperature, and bumps on the deposited film surface. It was used as a precursor of titanium oxide at low deposition temperatures (<400 ° C) without causing haze or hazeiness. However, this precursor has an unsaturated Ti (IV) center that is highly reactive to air and moisture. In addition, Ti-O bonds readily decompose at high temperatures, resulting in poor step coverage, which is an advantage of the MOCVD process.

To solve this problem, modified alkoxides with saturated coordination states such as Ti (O ⁱ Pr) ₂ (tmhd) ₂ (tmhd = 2,2,6,6-tetramethyl-3,5-heptanedionate) ) Has been studied. Ti (O ⁱ Pr) ₂ (tmhd) ₂ is known for its high vapor pressure, stability in air and excellent thermal stability [J.-H. Lee and S.-W. Rhee, J. Electrochem. Soc ., 1999 , 146 , 3783; J.-H. Lee and S.-W. Rhee, Electrochem. Solid-State Lett ., 1999 , 2 , 507]. _{^{Ti (O i Pr) 2 (}} tmhd) by two alkoxide and titanium precursor with two β- diketonates ligand, such as _{^{2 (O i Pr) Ti 2}} (tbaoac) 2 (tbaoac = tert-butylacetoacetate) the The results of the deposition of the thin films using the polymers have been reported [R. Bhakta, R. Thomas, F. Hipler, HF Bettinger, J. Muller, P. Ehrhartb, A. Devi, J. Mater. Chem., 2004, 14, 3231.

In recent years, a method of replacing a functional donor group having two or more donors (eg, dimethylaminoethoxide, dimethylaminopropoxide, etc.) with an alkoxide is also attempted. [K. Szczegot and M. Nowakowska, Polimery ( Warsaw ), 1977 , 22 , 399].

Ti (O ⁱ Pr) ₃ (dmae) and Ti (O ⁱ Pr) ₂ (dmae) ₂ were synthesized by replacing one or two O ⁱ Pr with dmae in 4 coordination Ti (O ⁱ Pr) ₄ . Moisture less sensitive than alkoxides, using these compounds as precursors, a good quality TiO ₂ film was obtained by liquid injection CVD [AC Jones, TJ Leedham, PJ Wright, MJ Crosbie, KA] Fleeting, DJ Otway, P. O'Brien, and ME Pemble, J. Mater. Chem ., 1998 , 8 , 1773].

Ti (dmae) ₄ , which consists of all four ligands of dmae, is less sensitive to deposition temperature than Ti (O ⁱ Pr) ₂ (tmhd) ₂ and results in no raised or blurry parts. J. -H. Lee, JY Kim, J.-Y. Shim, and S.-W. Rhee, J. Vac. Sci. Technol. A, 1999 , 17 , 3033].

, L. Niinist

, and P. Haussalo, Chem. Mater., 1993, 5, 1174; A. Rahtu and M. Ritala, Chem. Vap. Deposition, 2002, 8, 21]나 Ti(OC₂H₅)₄ [참조: M. Ritala, M. Leskel

, and E. Rauhala, Chem. Mater., 1994, 6, 556; J. Aarik, A. Aidla, V. Sammelselg, T. Uustare, M. Ritala, and M. Leskel

, Thin Solid Films, 2000, 370, 163; A. Rahtu, K. Kukli, and M. Ritala, Chem. Mater., 2001, 13, 817]같은 알콕사이드 화합물을 사용하거나 TiCl₄ [참조: M. Ritala, M. Leskel

, E. Nyk

nen, P. Soininen, and L. Niinist

, Thin Solid Films, 1993, 225, 288; J. Aarik, A. Aidla, A.-A. Kiisler, T. Uustare, and V. Sammelselg, Thin Solid Films, 1997, 305, 270; R. Matero, A. Rahtu, and M. Ritala, Chem. Mater., 2001, 13, 4506]나 TiI₄ [참조: K. Kukli, M. Ritala, M. Schuisky, M. Leskel

, T. Sajavaara, J. Keinonen, T. Uustare, and A. H

rsta, Chem. Vap. Deposition, 2000, 6, 303; K. Kukli, A. Aidla, J. Aarik, M. Schuisky, A. H

rsta, M. Ritala, and M. Leskel

, Langmuir, 2000, 16, 8122]와 같은 할라이드 화합물을 사용하는데, 대분분의 경우에 산소 소스로 물을 넣어준다.On the other hand, researches for producing titania thin films using ALD have been actively conducted in recent years. Titanium source is mainly Ti (OiC ₃ H ₇ ) ₄ [M. Ritala, M. Leskel

, L. Niinist

, and P. Haussalo, Chem. Mater. , 1993 , 5 , 1174; A. Rahtu and M. Ritala, Chem. Vap. Deposition , 2002 , 8 , 21] or Ti (OC ₂ H ₅ ) ₄ [M. Ritala, M. Leskel

, and E. Rauhala, Chem. Mater. , 1994 , 6 , 556; J. Aarik, A. Aidla, V. Sammelselg, T. Uustare, M. Ritala, and M. Leskel

, Thin Solid Films , 2000 , 370 , 163; A. Rahtu, K. Kukli, and M. Ritala, Chem. Alkoxide compounds such as Mater ., 2001 , 13 , 817] or TiCl ₄ [M. Ritala, M. Leskel

, E. Nyk

nen, P. Soininen, and L. Niinist

, Thin Solid Films , 1993 , 225 , 288; J. Aarik, A. Aidla, A.-A. Kiisler, T. Uustare, and V. Sammelselg, Thin Solid Films , 1997 , 305 , 270; R. Matero, A. Rahtu, and M. Ritala, Chem. Mater ., 2001 , 13 , 4506] or TiI ₄ [K. Kukli, M. Ritala, M. Schuisky, M. Leskel

, T. Sajavaara, J. Keinonen, T. Uustare, and A. H

rsta, Chem. Vap. Deposition , 2000 , 6 , 303; K. Kukli, A. Aidla, J. Aarik, M. Schuisky, A. H

rsta, M. Ritala, and M. Leskel

, Langmuir , 2000 , 16 , 8122]. In most cases, water is used as the oxygen source.

As described above, titanium compounds known in the related art have disadvantages that materials having a low deposition temperature are sensitive to air or moisture and materials in the air or thermally stable are very low in vapor pressure despite the advantages of the compounds. Therefore, the development of new titanium oxide precursors to increase thermal stability and volatility is significant.

In order to solve the problems of the existing compounds, the present inventors have introduced alkoxides in which at least one of the three methyl groups of tert-butoxide is substituted with a functional group larger than the methyl group as a ligand to develop a new titanium oxide precursor. The novel titanium oxide precursor according to the present invention is much more stable than the conventional titanium alkoxide compound because the titanium center metal is surrounded by relatively larger functional groups than tert-butoxide or isopropoxide, thereby reducing the intermolecular interaction. Yet the new titanium oxide precursor according to the invention is more responsive because the ligand is simpler than the compounds that are more stabilized by complex ligands and thus become more stable in the coordination sites of titanium (eg β-diketonate compounds).

It is an object of the present invention to provide a titanium oxide precursor that is thermally stable and has increased volatility to form a high quality titanium oxide film.

In order to achieve the above object, the present invention provides an organic titanium compound that is a novel titanium oxide precursor of the formula (1).

[Formula 1]

In the above formula, R ¹ , R ² and R ³ are independently of each other a C ₁ -C ₄ linear or branched alkyl group, except that R ¹ , R ² and R ³ are all methyl groups. Preferably R ¹ and R ² are each independently selected from CH ₃ , C ₂ H ₅ , nC ₃ H ₇ , iC ₃ H ₇ , nC ₄ H ₉ and tC ₄ H ₉ , R ³ is C ₂ H ₅ , nC ₃ H ₇ , iC ₃ H ₇ , nC ₄ H ₉ and tC ₄ H ₉ , more preferably R ¹ is CH ₃ and R ² and R ³ are C ₂ H ₅ .

Hereinafter, the present invention will be described in more detail.

The compound represented by Chemical Formula 1 according to the present invention may be reacted with a tetrakis dialkyl amido titanium compound represented by the following Chemical Formula 2 and an alcohol compound represented by Chemical Formula 3 as a starting material in a nonpolar solvent, or as a starting material. It can be prepared by reacting titanium chloride with the formula (4) and the alkali metal salt of the alcohol represented by the formula (5).

[Formula 2]

Ti (NR ' ₂ ) ₄

[Formula 3]

HOCR ¹ R ² R ³

[Formula 4]

TiCl ₄

[Formula 5]

M'OCR ¹ R ² R ³

Wherein R ¹ , R ² and R ³ are as described above, R 'is methyl or ethyl and M' is Li, Na or K.

In order to prepare the titanium oxide precursor [Ti (OCR ¹ R ² R ³ ) ₄ ] of the present invention, the compound [Ti (NR ' ₂ ) ₄ ] represented by the formula ( ₂ ) is used as a starting material. Reaction with HOCR ¹ R ² R ³ ) is shown in Scheme 1 below.

Scheme 1

Ti (NR ' ₂ ) ₄ + 4 HOCR ¹ R ² R ³ → Ti [OCR ¹ R ² R ³ ] ₄ + 4 HNR' ₂

According to the reaction, a solution of a nonpolar solvent such as hexane, pentane or toluene, in which 4 equivalents of the compound of formula 3 is dissolved in a solution of a nonpolar solvent such as hexane, pentane or toluene, in which one equivalent of the compound of formula 2 is dissolved, After slowly adding, the reaction was carried out for 12 hours, and then the solvent was removed under reduced pressure to obtain a compound of Formula 1.

Ti (NR ' ₂ ) _{4, which} is a starting material used in the reaction, contains a highly reactive dialkylamido ligand and has an acidic hydrogen (HOCR ¹ R ² R ³ ) which is relatively acidic compared to that of the secondary amine. [Ti (OCR ¹ R ² R ³ ) ₄ ] of the general formula (1), which is a precursor of the novel titanium oxide, is prepared by a 4 equivalent substitution reaction.

As another reaction process for preparing the titanium oxide precursor [Ti (OCR ¹ R ² R ³ ) ₄ ] of the present invention, the compound represented by Chemical Formula 4 as a starting material of titanium chloride (TiCl ₄ ) A reaction for preparing the compound represented by Chemical Formula 1 by reacting with an alkali metal salt (M'OCR ¹ R ² R ³ ) of an alcohol which is the compound represented by 5 is shown in Scheme 2 below.

Scheme 2

TiCl ₄ + 4 M'OCR ¹ R ² R ³ → Ti (OCR ¹ R ² R ³ ) ₄ + 4 M'Cl

According to the reaction, 1 equivalent of titanium chloride (compound of formula 4), which is a starting material, and 4 equivalents of compound of Formula 5 were reacted in tetrahydrofuran, toluene, or hexane for 1 hour, refluxed for 12 hours, and filtered under reduced pressure. Then, the solvent is removed from the filtrate under reduced pressure to obtain a compound of formula 1.

The novel titanium oxide precursor [Ti (OCR ¹ R ² R ³ ) ₄ ] represented by Chemical Formula 1 has an affinity for an organic solvent because an alkyl group is bonded to carbon bonded to oxygen of an alkoxide which is bonded to a metal. In addition, by introducing various alkyl groups of different sizes to the carbon in the α-position to the oxygen of the alkoxide, the central metal bonded to oxygen is intermolecular interaction with the oxygen of the neighboring ligand as compared with titanium t-butoxide or titanium isopropoxide. This precursor can exist as a monomer because it impairs steric hindrance to prevent action. Due to such structural characteristics, the titanium oxide precursor represented by Chemical Formula 1 is a stable liquid at room temperature, and has high solubility in organic solvents such as pentane, hexane, diethyl ether, tetrahydrofuran, toluene, and high volatility. In addition, it does not contain a halogen element, is stable at room temperature, which is advantageous for storage, and can be used to obtain a titanium oxide film of better quality.

Hydrogen and carbon atom nuclear magnetic resonance spectra ( ¹ H, ¹³ C NMR) and infrared spectra (IR) were used to analyze the properties of the organic titanium compound synthesized in the present invention. Investigations were performed using thermogravimetric / differential thermal analysis (TG / DTA).

1 and 2 show the nuclear and magnetic resonance spectra of hydrogen and carbon atoms of Ti (mp) ₄ (mp = 3-methyl-3-pentoxide) prepared in Example 1, wherein Ti (NMe ₂ ) was used as a starting material. The peak of the methyl group of ₄ disappeared and the peak of the 3-methyl-3-pentoxy ligand used as a reaction material appeared.

The peak of the hydroxyl group of 3-methyl-3-pentanol used as a reactant in the infrared spectrum of Ti (mp) ₄ of Example 1 shown in FIG. 3 disappeared and the peak indicating the bonding of titanium and oxygen at 615 cm ⁻¹ . Appeared.

4 shows a TGA / DTA graph (10 ° C./min to 800 ° C., 100 cc / min N ₂ purge) of Ti (mp) ₄ prepared in Example 1. FIG. Mass loss of about 10% occurred at 50-200 ° C. and sudden mass loss at 250 ° C. At 250 ° C., a mass loss of over 88% was observed, with about 12% residual material. The TGA graph also shows that T _1/2 is 248 ° C.

The novel organic titanium compound developed in the present invention is a precursor for producing various oxide thin films including titanium, including PZT (lead-zirconium-titanium oxide) thin films, and metal organic chemical vapor deposition (MOCVD), which is widely used in semiconductor manufacturing processes. ) Or atomic layer deposition (ALD) process.

The invention is better understood by the following examples, which are intended for purposes of illustration of the invention and are not intended to limit the scope of protection defined by the appended claims.

Example

All experiments were performed in an inert argon or nitrogen atmosphere using a glove box or Schlenk line. Example 1 Structure and physical properties of the reaction product obtained in the hydrogen nuclear magnetic resonance ^{(1 H nuclear magnetic resonance, NMR} ), the carbon atom nuclear magnetic resonance ⁽¹³ C NMR), elemental analysis (elemental analysis, EA), mass Mass spectroscopy, thermogravimetric / differential thermal analysis (TG / DTA) was used to confirm.

Preparation of Titanium Oxide Precursor

Example 1 Synthesis of Tetrakis (3-methyl-3-pentoxy) titanium (IV) [Ti (mp) ₄ ]

Tetrakisdimethylamidotitanium (IV) (2.00 g, 8.92 mmol) was dissolved in a flame dried 125 mL Schlenk flask containing hexane (50 mL). To this solution, a solution of mpH (3-methyl-3-pentanol, 3-methyl-3-pentanol) (3.65 g, 35.72 mmol) in hexane (30 mL) was slowly added and stirred for 12 hours. The solvent was removed under reduced pressure and distillation under reduced pressure (140 ° C./10 ⁻² Torr) gave 3.64 g of the title compound as a yellow liquid (yield: 98.4%).

¹ H NMR (C ₆ D ₆ , 300.13 MHz): δ 1.02 (t, 24H, J = 7.5 Hz, CCH ₂ C H ₃ ), 1.30 (s, 12H, CC H ₃ ), 1.62 (q, 16H, J = 7.5 Hz, CC H ₂ CH ₃ ).

¹³ C { ¹ H} NMR (C ₆ D ₆ , 75.03 MHz): δ 85.0 (O C CH ₃ ), 35.0 (C ( C H ₂ CH ₃ ) ₂ ), 27.4 (C C H ₃ ), 8.9 (C (CH ₂ C H ₃ ) ₂ ).

Elemental Analysis C ₂₄ H ₅₂ O ₄ Ti {Calcd. (found)}: C, 58.13 (58.04); H, 10.57 (11.05).

As described above, the new organic titanium compound, which is a titanium oxide precursor according to the present invention, is less volatile than conventionally known alkoxide compounds and is advantageous for storage, and in particular, a metal organic chemical vapor deposition method (MOCVD) requiring excellent quality of oxide film. ) Or as the titanium oxide precursor of the atomic layer deposition method (ALD), and can be usefully used as a precursor for producing an oxide thin film containing titanium oxide.

Claims (6)

An organic titanium compound represented by the following formula (1). [Formula 1]

(Wherein R ¹ , R ² and R ³ are independently of each other a C ₁ -C ₄ linear or branched alkyl group, except that R ¹ , R ² and R ³ are all methyl groups.) The method of claim 1, R ¹ and R ² are each independently selected from CH ₃ , C ₂ H ₅ , nC ₃ H ₇ , iC ₃ H ₇ , nC ₄ H ₉ and tC ₄ H ₉ , and R ³ is C ₂ H ₅ , nC ₃ An organic titanium compound selected from H ₇ , iC ₃ H ₇ , nC ₄ H ₉ and tC ₄ H ₉ . The method of claim 1, An organic titanium compound, wherein R ¹ is CH ₃ , R ² and R ³ are C ₂ H ₅ . A method for preparing an organotitanium compound of formula (1) according to claim 1 comprising reacting an amido compound of titanium of formula (2) with an alcohol compound of formula (3). [Formula 2] Ti (NR ' ₂ ) ₄ [Formula 3] HOCR ¹ R ² R ³ (Wherein R ¹ , R ² and R ³ are as defined in claim 1 and R 'is methyl or ethyl.) A method for producing an organotitanium compound of formula (1) according to claim 1 comprising reacting titanium chloride represented by formula (4) with an alkali metal salt of an alcohol represented by formula (5). [Formula 4] TiCl ₄ [Formula 5] M'OCR ¹ R ² R ³ (Wherein R ¹ , R ² and R ³ are as defined in claim 1 and M ′ is Li, Na or K.) delete

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