KR20050081302A - Precursors of titanium oxide and preparation method thereof - Google Patents

Abstract

The present invention relates to a titanium oxide precursor of the formula (1) and a method for producing the titanium oxide precursor according to the present invention is thermally stable and improved volatility can be advantageously used in the production of titanium oxide thin film.

Where

Two R are independently of each other a C ₁ -C ₄ linear or branched alkyl group,

Two R ′ are independently of each other a linear or branched alkyl group of C ₁ -C ₄ or CR ″ ₂ CH ₂ NR ^* ₂ , wherein R ″ and R ^* are a linear or branched alkyl group of C ₁ -C ₄ ) to be.

Description

Titanium oxide precursor and its manufacturing method {PRECURSORS OF TITANIUM OXIDE AND PREPARATION METHOD THEREOF}

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

The development of the electronics industry in recent decades has played a major role in raising the standard of living for humans. The development direction of the electronics industry is changing due to miniaturization, high integration, and improvement in processing speed, and development of new electronic materials and development of thin film manufacturing technology are essential for high integration of circuits, and particularly high dielectric constant materials having large storage capacity. This is required.

Metal organic chemical vapor deposition (MOCVD) is a method used to prepare various oxide thin films. Compared to other processes, the process is simpler, the layer coverage is superior to other techniques, easy to control ingredients, and easy to convert to mass production.

For the manufacture of thin films using MOCVD or atomic layer deposition (ALD), the development and characterization of the precursors used in this process is essential. 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 surface of the thin film to be deposited. It was used as a precursor of titanium oxide at low deposition temperatures (<400 ^o C), without causing haze or haze. 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].

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 . It is less sensitive to moisture than alkoxides, which is advantageous for storage. Using these compounds as precursors, high quality TiO ₂ films were 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].

On the other hand, researches for producing titania thin films using ALD have been actively conducted in recent years. Titanium sources are mainly Ti (OiC ₃ H ₇ ) ₄ [M. Ritala, M. Leskelae, L. Niinistae, and P. Haussalo, Chem. Mater. , 1993 , 5 , 1174; A. Rahtu and M. Ritala, Chem. Vap. Deposition , 2002 , 8 , 21], Ti (OC ₂ H ₅ ) ₄ [M. Ritala, M. Leskelae, and E. Rauhala, Chem. Mater. , 1994 , 6 , 556; J. Aarik, A. Aidla, V. Sammelselg, T. Uustare, M. Ritala, and M. Leskelae, 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. Leskelae, E. Nykaenen, P. Soininen, and L. Niinisto, 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], TiI ₄ [K. Kukli, M. Ritala, M. Schuisky, M. Leskelae, T. Sajavaara, J. Keinonen, T. Uustare, and A. Harsta, Chem. Vap. Deposition , 2000 , 6 , 303; Halogen compounds such as K. Kukli, A. Aidla, J. Aarik, M. Schuisky, A. Harsta, M. Ritala, and M. Leskelae, Langmuir , 2000 , 16 , 8122]. Use water as a source.

As described above, titanium compounds known in the related art have a disadvantage that materials having a low deposition temperature are sensitive to air or moisture, and materials that are stable to air or heat have a very low vapor pressure despite the advantages of the compounds.

Thus, the development of new titanium oxide precursors to increase thermal stability and volatility is significant.

In order to provide a compound having a new ligand that solves the problems of the alkoxide compound, the present inventors have only a nitrogen and oxygen atom ligand coordinated to titanium, which does not cause contamination of carbon or halogens, and improves thermal stability and volatility. Titanium oxide precursors have been developed.

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 a novel titanium oxide precursor of the formula (1):

Formula 1

Where

Two R are independently of each other a C ₁ -C ₄ linear or branched alkyl group,

Two R ′ are independently of each other a linear or branched alkyl group of C ₁ -C ₄ or CR ″ ₂ CH ₂ NR ^* ₂ , wherein R ″ and R ^* are a linear or branched alkyl group of C ₁ -C ₄ ) to be.

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

In the compound of Formula 1, R is CH ₃ , C ₂ H ₅ , CH (CH ₃ ) ₂ or C (CH ₃ ) ₃ , and R 'is CH ₃ , C ₂ H ₅ , CH (CH ₃ ) ₂ , C Preferred are compounds (CH ₃ ) ₃ or CR ″ ₂ CH ₂ NR ^* ₂ .

The compound of Chemical Formula 1 according to the present invention is obtained by reacting an alkali metal salt of Chemical Formula 3 with a halogenated titanium, such as titanium tetrachloride of Chemical Formula 2, as a starting material in an organic solvent to obtain a compound of Chemical Formula 4, and then dialkyl of Chemical Formula 5. It can be prepared by reacting with an alkali metal salt of an amide to induce a substitution reaction:

TiX ₄

M ₂ [RN = CHCH = NR]

Ti [RNCH = CHNR] X ₂

MOR '

Wherein R and R 'are as defined above, X is F, Cl, Br or I and M is Li, Na or K.

The reaction for preparing the titanium oxide Ti [RNCH = CHNR] (OR ′) ₂ of the present invention may be represented by the following Scheme 1 and Scheme 2:

TiX ₄ + M ₂ [RN = CHCH = NR] → Ti [RNCH = CHNR] X ₂ + 2 MX

Ti [RNCH = CHNR] X ₂ + 2 MOR '→ Ti [RNCH = CHNR] (OR') ₂ + 2 MX

Ti [RNCH = CHNR] (OR ') _{2, which} is a novel titanium oxide precursor of Formula 1, is a stable complex compound, and a non-polar alkyl group is bonded at the α-carbon position to the oxygen of the alkoxide to which the metal is bonded. It can be present as a monomer because it has high affinity for the chelant and prevents the central metal from causing intermolecular interactions with nitrogen or oxygen of neighboring ligands. Due to these structural characteristics, the precursor for titanium oxide of Chemical Formula 1 is a stable solid at room temperature, and has high solubility in organic solvents such as pentane, hexane, diethyl ether, tetrahydrofuran, toluene, etc. Since it does not contain a halogen element and is convenient for storage, these can be used and a titanium oxide film of higher quality can be obtained.

The titanium oxide precursor according to the present invention is preferably applicable to metal organic chemical vapor deposition (MOCVD) processes widely used in semiconductor manufacturing processes.

The invention can be 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. The reaction products obtained in Examples 1 and 2, respectively, were prepared using ¹ H nuclear magnetic resonance (NMR), carbon atom nuclear magnetic resonance ( ¹³ C NMR) and elemental analysis (EA). Analyzed.

Preparation of Titanium Oxide Precursor

Example 1: (glyoxalvis t -Butylimine)) bis (toxy) titanium [Ti ( ^t Bu-dad) (O ^t Bu) ₂ Synthesis

Step 1): Synthesis of dichloroglyoxalbis ( t -butylimine) titanium [Ti ( ^t Bu-dad) Cl ₂ ]

In a fire dried 125 mL Schlenk flask, tetrahydrofuran (40 mL), ^t Bu-dad ( tert -butyl-1,4-diaza-1,3-diene) (3.4 g, 20 mmol) and excess lithium ( Li wire) (27 mmol) was added thereto. The mixture was stirred at room temperature for 12 hours. The mixture was slowly added to a solution of titanium (IV) chloride (2.1 mL, 20 mmol) dissolved in hexane (30 mL) at -90 ° C, and the temperature was raised to room temperature, followed by stirring for 12 hours. Subsequently, the solvent was removed under reduced pressure and then extracted several times with hexane. The solvent was removed under reduced pressure to give 3.51 g of the title compound as a dark green solid (yield 61%).

¹ H NMR (C ₆ D ₆ , 300.13 MHz): δ 5.87 (s, 2H C H N), 1.12 (s, 18H, (C H ₃ ) ₃ ).

¹³ C { ¹ H} NMR (C ₆ D ₆ , 75.03 MHz): δ 98.21 (s, C HN), 63.01 (s, C (CH ₃ ) ₃ ), 30.68 (s, ( C H ₃ ) ₃ ).

Elemental Analysis C ₁₀ H ₂₀ N ₂ Cl ₂ Ti {calculated (calculated)}: C, 41.84 (41.87); H, 7.02 (7.22); N, 9.76 (10.03).

Step 2): (glyoxal bis (t - butyl imine)) bis (butoxy) Synthesis of titanium [Ti ^(t-Bu dad) (O ^t Bu) _2]

In a flame-dried 125 mL Schlenk flask, dichloroglyoxalbis ( t -butylimine) titanium (1.34 g, 4.67 mmol) prepared in step 1) was dissolved in tetrahydrofuran (50 mL). To this solution a solution of KO ^t Bu (1.15 g, 10.30 mmol) dissolved in tetrahydrofuran (30 mL) was added slowly at -90 ° C. The mixture was stirred at −90 ° C. for 3 hours and then heated to room temperature and stirred for 12 hours. The solvent was removed under reduced pressure, followed by extraction with hexane several times, and then the solvent was removed from the filtrate under reduced pressure to obtain 1.10 g of the title compound as a red liquid (yield 64%).

¹ H NMR (C ₆ D ₆ , 300.13 MHz): δ 5.94 (s, 2H C H N), 1.37 (s, 18H (C H ₃ ) ₃ , O ^t Bu), 1.31 (s, 18H, (C H ₃ ) ₃ ).

¹³ C { ¹ H} NMR (C ₆ D ₆ , 75.03 MHz): δ 102.98 (s, C HN), 57.15 (s, C (CH ₃ ) ₃ ), 33.37 (s, (( C H ₃ ) ₃ , ^{O t Bu), 31.82 (s} , (C H 3) 3).

Elemental Analysis C ₁₈ H ₃₈ N ₂ O ₂ Ti {calculated (found)}: C, 59.66 (57.60); H, 10.57 (10.10); N, 7.73 (7.21).

Example 2: (glyoxalvis ( t -Butylimine)) bis (1-dimethylamino-2-methyl-2-propoxy) titanium [Ti ( ^t Bu-dad) (dmamp) ₂ Synthesis

In a fire dried 125 mL Schlenk flask, dichloroglyoxalbis ( t -butylimine) titanium (2.10 g, 7.01 mmol) prepared in step 1) of Example 1 was dissolved in tetrahydrofuran (50 mL). Nadmamp (dmamp = Me ₂ NCH ₂ CMe ₂ O) ((2.20 g, 14.4 mmol) was slowly added to the solution at -90 ° C. The mixture was stirred at -90 ° C for 3 hours, and then the temperature was raised to room temperature. After stirring for 12 hours, the solvent was removed under reduced pressure and extracted several times with hexane, and then the solvent was removed from the filtrate under reduced pressure to obtain 2.20 g of the title compound as a red liquid (yield 70%).

¹ H NMR (C ₆ D ₆ , 300.13 MHz): δ 5.95 (s, 2H, C H N), 2.32 (s, 16H, N (C H ₃ ) ₂ , C H ₂ ), 1.42 (s, 12H, C (C H ₃ ) ₂ ), 1.34 (s, 18H, (C H ₃ ) ₃ ).

¹³ C { ¹ H} NMR (C ₆ D ₆ , 75.03 MHz): δ 102.81 (s, C HN), 72.00 (s, C H ₂ ), 57.46 (s, ( C (CH ₃ ) ₃ ), 48.42 ( s, N ( C H ₃ ) ₂ ), 31.85 (C ( C H ₃ ) ₃ ), 30.56 (C ( C H ₃ ) ₂ ).

Elemental Analysis C ₂₂ H ₄₈ N ₄ O ₂ Ti {calculated (found)}: C, 58.91 (59.22); H, 10.79 (10.70); N, 12.49 (12.80).

Nuclear Magnetic Resonance Spectroscopy ( ¹ H NMR) spectra of the intermediate synthesized in Step 1) of Example 1 and the titanium oxide precursor synthesized in Examples 1 and 2 are shown in FIGS. 1, 2, and 4, respectively. Carbon atom nuclear magnetic resonance spectroscopy ( ¹ C NMR) spectra of the titanium oxide precursor synthesized in 2 and 2 are shown in FIGS. 3 and 5, respectively.

As described above, the titanium oxide precursor according to the present invention is not only excellent in thermal stability and volatility, but also less sensitive to moisture and advantageous in storage, and therefore, metal organic chemical vapor deposition (MOCVD) or It can be usefully used as a titanium precursor having a novel ligand for atomic layer deposition (ALD).

1 is a hydrogen atom nuclear magnetic resonance spectroscopy ( ¹ H NMR) spectrum of the Ti ( ^t Bu-dad) Cl ₂ intermediate prepared in step 1) of Example 1,

2 is a hydrogen atom nuclear magnetic resonance spectroscopy ( ¹ H NMR) spectrum of the Ti ( ^t Bu-dad) (O ^t Bu) ₂ compound prepared in Example 1,

3 is a carbon atom nuclear magnetic resonance spectroscopy ( ¹³ C NMR) spectrum of the Ti ( ^t Bu-dad) (O ^t Bu) ₂ compound prepared in Example 1,

4 is a hydrogen atom nuclear magnetic resonance spectroscopy ( ¹ H NMR) spectrum of the Ti ( ^t Bu-dad) (dmamp) ₂ compound prepared in Example 2,

5 is a carbon atom nuclear magnetic resonance spectroscopy ( ¹³ C NMR) spectrum of the Ti ( ^t Bu-dad) (dmamp) ₂ compound prepared in Example 2. FIG.

Claims (6)

Titanium oxide precursor of Formula 1 Formula 1 Where Two R are independently of each other a C ₁ -C ₄ linear or branched alkyl group, Two R ′ are independently of each other a linear or branched alkyl group of C ₁ -C ₄ or CR ″ ₂ CH ₂ NR ^* ₂ , wherein R ″ and R ^* are a linear or branched alkyl group of C ₁ -C ₄ ) to be. The compound of claim 1, wherein R is CH ₃ , C ₂ H ₅ , CH (CH ₃ ) ₂ or C (CH ₃ ) ₃ , and R ′ is CH ₃ , C ₂ H ₅ , CH (CH ₃ ) ₂ , C Titanium oxide precursor, characterized by (CH ₃ ) ₃ or CR ″ ₂ CH ₂ NR ^* ₂ . A titanium oxide precursor according to claim 1 comprising reacting a titanium halide of formula (2) with a compound of formula (3) in an organic solvent to obtain a compound of formula (4) and then reacting it with an alkali metal salt of an alkoxide of formula (5): Method of preparation of material: Formula 2 TiX ₄ Formula 3 M ₂ [RN = CHCH = NR] Formula 4 Ti [RNCH = CHNR] X ₂ Formula 5 MOR ' Wherein R and R 'are as defined in claim 1, X is F, Cl, Br or I, and M is Li, Na or K. A method of growing titanium oxide using the titanium oxide precursor according to claim 1. The method of claim 4, wherein the titanium oxide is formed by metal organic chemical vapor deposition (MOCVD). The method of claim 4, wherein the titanium oxide is formed by atomic layer deposition (ALD).