KR20040074754A - A precursor of zirconium dioxide, preparation method thereof and process for the formation of thin film using the same - Google Patents

Abstract

PURPOSE: A precursor of zirconium dioxide, a preparation method thereof and a method for forming thin film using the same are provided, which zirconium dioxide precursor has thermal stability and improved volatility, so that high quality of zirconium thin film can be formed. CONSTITUTION: The precursor of zirconium dioxide represented by formula (1) is provided, wherein R is C1-4 alkyl optionally containing fluor; and R' is C1-4 alkyl optionally containing fluor or SiR'3. The method for preparing the precursor of zirconium dioxide of formula (1) comprises reacting zirconium complex of formula (2) with alkali metal salt of alcohol of formula (3), wherein X is chlorine, bromine or iodine; and M is Li, Na or K. The method for preparing the precursor of zirconium dioxide of formula (1) comprises reacting zirconium complex of formula (2) with alcohol of formula (4) in the presence of tertiary amine. The method for forming thin film comprises carrying out MOCVD system(Metal-Organic Chemical Vapor Deposition Systems) or ALD(atomic layer deposition) using the precursor of zirconium dioxide of formula (1).

Description

A zirconium oxide precursor, a method of manufacturing the same, and a method of forming a thin film using the same {A PRECURSOR OF ZIRCONIUM DIOXIDE, PREPARATION METHOD THEREOF AND PROCESS FOR THE FORMATION OF THIN FILM USING THE SAME}

The present invention relates to a novel precursor for zirconium oxide, and more particularly to a zirconium alkoxide complex compound useful as a zirconium oxide precursor and a method for producing a zirconium-containing oxide thin film using the same.

Recently, the direction of development of the electronics industry is changing to miniaturization, high integration, and processing speed. The development of new electronic materials and thin film manufacturing technology are essential for high integration of circuits. The metal organic chemical vapor deposition (MOCVD) process, which is used in the manufacture of various oxide thin films in the thin film manufacturing technology, is relatively simple in equipment, uniform in layer covering, easy to control ingredients, and difficult to convert to mass production. There is no advantage. In order to manufacture thin films using such a MOCVD process, it is essential to understand the development and characteristics of precursors used in this process. The precursor for MOCVD must have a sufficiently high vapor pressure below 200 ° C, be sufficiently thermally stable during heating to evaporate, decompose rapidly at the substrate temperature of 350 to 500 ° C without decomposition of organic matters, and during storage It must be stable enough to air and moisture. It should also be nontoxic or less toxic to the precursor itself or to the decomposition products, and should be simple in synthesis and low in raw material costs.

Zirconium oxide, zirconia (ZrO ₂ ), has a high dielectric constant, wide energy band spacing, and high refractive index and is mechanically and chemically stable, so it is made into a thin film and used as a dielectric for storage capacitors in dynamic random access memory (DRAM). The precursor can be used as a raw compound of Pb (Zr, Ti) O ₃ , a ferroelectric oxide, in a nonvolatile memory.

The precursors that have been used to make zirconia into a thin film are classified into four types, and there are compounds including inorganic salts of zirconium such as zirconium chloride or zirconium nitrate, alkoxide compounds, dialkylamido compounds and β-diketonate. .

Among these, zirconium chloride (ZrCl ₄ ) has low volatility, and when the oxide thin film is manufactured using the same, the deposition temperature is increased to 800 ° C. or more, and the thin film is contaminated with chlorine (RN Tauber, AC Dumbri, RE Caffrey, J. Electrochem. Soc ., 1971, 118 , 747). Zirconium nitrate complex Zr (NO ₃ ) ₄ is used to deposit high purity zirconia at growth temperatures below 300 ° C, but the use of anhydrous nitrate complexes in MOCVD processes has serious problems in stability (RC Smith, T. Ma. , N. Hoilien, LY Tsung, MJ Bevan, L. Colombo, J. Roberts, SA Campbell and W. Gladfelter, Adv. Mater. Opt. Electron ., 2000, 10 , 105).

Zirconium alkoxide Zr (OR) ₄ can be used as a precursor for MOCVD because a low deposition temperature and carbon contamination-free thin films are deposited (JJ Gallegos, TL Ward, TJ Boyle, MA Rodriguez and LP Francisco, Chem. Vap. Deposition) , 2000, 6 , 21). Zirconium, the central metal, tends to be dimers or polymers to satisfy 6-8 coordination (DC Bradley, RC Mehrotra and DP Gaur, Metal Alkoxides , Academic Press, New York, 1978, pp 10-12). Among the zirconium alkoxide compounds, Zr (O ^t Bu) ₄ , which can be steric hindrance by tert -butyl group, is highly volatile and is used as the best precursor for zirconia thin film (BJ Gould, IM Povey, ME Pemble and WR Flavell, J. Mater. Chem. , 1994, 4 , 1815). However, Zr (O ^t Bu) ₄ is decomposed to very susceptible to react with trace amounts of moisture in the air and moisture (DC Bradley, Chem. Rev. , 1989, 89, 1317). Due to these characteristics, it is not desirable to apply this compound to solution-injected MOCVD (LI-MOCVD), which is used in a solution state because of the pre-reaction and short shelf life in the MOCVD reactor.

In order to prevent zirconium alkoxide from oligomerization, studies are being actively made to introduce monomer precursors having increased volatility by introducing a bidentate donor functionalized ligand. However, the introduction of dmae (2-dimethylaminoethanol) and dmap (1-dimethylamino-2-propanol) into Zr (OR) ₄ (R = ⁱ Pr or ^t Bu) resulted in [Zr (O ⁱ Pr) ₃ (dmap)] ₂ and [Zr (O ⁱ Pr) ₃ (bis-dmap)] ₂ (KA Fleeting, P. O'Brien, AC Jones, DJ Otway, AJP White and DJ Williams, J. Chem. Soc., Dalton Trans ., 1999, 2853), Zr (O ^t Bu) ₂ (dmae) ₂ ] ₂ (R. Matero, M. Ritala, M. Leskala, AC Jones, PA Williams, JF Bickley, A. Steiner, TJ Relatively nonvolatile asymmetric binuclear complexes such as Leedham and HO Davies, J. Non-Cryst. Solids, 2002, 303, 24) were obtained. These complexes cause disproportionation while [Zr (O ^t Bu) ₂ (dmae) ₂ ] ₂ evaporates in the MOCVD process, resulting in Zr (O ^t Bu) ₃ (dmae) and Zr (O ^t Bu) (dmae) ₃ (AC Jones, TJ Leedham, PJ Wright, MJ Crosbie, DJ Williams, PA Lane and P. O'Brien, Mater. Res. Soc. Symp. Proc., 1998, 495 , 11).

Meanwhile, the results of the method of preparing zirconia thin film by LI-MOCVD using Zr (dmae) ₄ compound have been published (JS Na, D.-H. Kim, K. Yong and S.-W. Rhee, J. Electrochem. Soc. , 2002, 149 , C23), and reported that the complex is present in equilibrium with monomers and dinucleates (AC Jones, J. Mater. Chem. , 2002, 12 , 2576). 1-methoxy-2-methyl-2-propanol (mmp) introduces two methyl groups at the α-carbon position close to the center metal to give steric hindrance to complex complexes. It has been reported that it exists as a monomer, Zr (O ^t Bu) ₂ (mmp) ₂ and Zr (mmp) ₄ have a 6-coordinate octahedral structure in the solid state (PA Williams, JL Roberts, AC Jones, PR Chalker, NL Tobin, JF Bickley, HO Davies, LM Smith and TJ Leedham, Chem. Vap.Deposition, 2002, 8 , 163). In particular, Jones group has one of _{^{Zr (O t Bu) 2 (}} mmp) 2 and Zr (mmp) ₄ produced superior zirconia thin film at 350 to 600 ℃ using a conventional MOCVD or LI-MOCVD bar.

Recently, researches using zirconium complex compounds with amido ligands have also been actively conducted. A study on the production of high quality zirconia by MOCVD method using tetrakisdiethylamidozirconium has been reported (A.Bastiani, GA Battiston, R. Gerbasi, M. Porchia and S. Daolio). , J. Phys. IV , 1995, 5 , C-525), and the Gordon group use a variety of amidozirconium compounds, such as Zr (NMe ₂ ) ₄ , Zr (NMeEt) ₄ or Zr (NEt ₂ ) ₄ . Discloses a process for producing high quality zirconia at substrate temperature of 50-500 ° C. by atomic layer deposition (ALD) (DM Hausmann, E. Kim, J. Becker, and LG Gordon, Chem. Mater). , 2002, 14 , 4350).

W. Clegg, Acta Crystallogr. Sect. C , 1987, 43 , and 789] have zirconium complexes containing β-diketonates such as Zr (acac) ₄ that are relatively stable in water or air because they have an eight-fold twisted square pillar structure in which zirconium metals are saturated. It is disclosed. These compounds decompose to form zirconia, but high evaporation temperatures are required to obtain sufficient vapor pressure (RC Smith, T. Ma, N. Hoilien, LY Tsung, MJ Bevan, L. Colombo, J. Roberts, SA Campbell). and W. Gladfelter, Adv. Mater. Opt. Electron ., 2000, 10 , 105), and also has the problem that the membrane is contaminated with carbon.

Meanwhile, Zr (tmhd) ₄ has the same structure as Zr (acac) ₄ and is more stable in moisture or air and is used for high purity zirconia, but a high deposition temperature of 600 ° C. or higher is required for oxide film deposition. Complexes containing fluorine are much more volatile but difficult to apply to microelectronics because fluorine decomposes the silicon substrate. The Jones group produced zirconia using Zr (tmhd) ₂ (O ^t Bu) ₂ or Zr (tmhd) ₂ (O ⁱ Pr) ₂ , but it requires high temperatures to evaporate these compounds and creates significant carbon contamination. (AC Jones, TJ Leedham, PJ Wright, MJ Crosbie, PA Lane, DJ Williams, KA Fleeting, DJ Otway, and P. O'Brien, Chem. Vap. Deposition , 1998, 4 , 46).

In order to solve the above problems, the present inventors have come to develop a new zirconia precursor which is less sensitive to moisture and advantageous to storage, and has improved thermal stability and volatility.

Accordingly, it is an object of the present invention to provide a zirconia precursor that is thermally stable and has increased volatility to form a high quality zirconium oxide film.

1 to 3 are graphs showing the results of thermogravimetric analysis (TGA) and differential thermal analysis (DTA) for the zirconium alkoxide complexes prepared in Examples 1 to 3 according to the present invention, respectively.

In order to achieve the above object, the present invention provides a novel zirconium oxide precursor represented by the following formula (1):

Formula 1

Where

R is an alkyl group of C _1-4 with or without fluorine, and R 'is an alkyl group of C _1-4 with or without fluorine or SiR " ₃ , wherein R" is an alkyl group of C _1-4 )to be.

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

The zirconium alkoxide complex compound represented by Chemical Formula 1 according to the present invention may be represented by the general formula Zr (bdk) ₃ (OR ′), and the compound may be represented by the compound Zr (bdk) ₃ ( X) and a compound represented by the formula (3) are reacted in a nonpolar solvent, or as a starting material in the presence of a tertiary amine such as triethylamine, the compound represented by the formula (2) Zr (bdk) ₃ (X) and (4) Compounds represented by the above can be prepared by reacting in a nonpolar solvent to induce a substitution reaction:

Where

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

Preferred examples of R in Formula 2 include CH ₃ , CF ₃ , CH (CH ₃ ) ₂ or C (CH ₃ ) ₃ , and, in Formula 3 or 4, preferred examples of R ′ include Si (CH ₃ ) _3. , CH (CF ₃ ) ₂ or CF ₃ .

In order to prepare the zirconium oxide {Zr (bdk) ₃ (OR ')} of the present invention, the compound represented by the formula (Zr (bdk) ₃ (X)) represented by Formula 2 as a starting material ( ) And the reaction can be represented by the following scheme 1:

As another reaction process for preparing the zirconium oxide {Zr (bdk) ₃ (OR ')} of the present invention, the compound {Zr (bdk) ₃ (X)} represented by Formula 2 as a starting material 3 Compound of formula 4 in the presence of a tertiary amine, for example triethylamine (Et ₃ N) ( ) To produce a zirconium oxide (Zr (bdk) ₃ (OR ′)) represented by Formula 1 can be represented, for example, by the following scheme 2:

According to the above reaction, a substitution reaction is performed at room temperature for about 12 hours in a nonpolar solvent such as hexane, pentane or toluene, and then filtered under reduced pressure, and the solvent is removed under reduced pressure from the resulting filtrate to obtain a white solid. In addition, Zr (bdk) ₄ and Zr (bdk) ₂ (OR ′) ₂ may be generated as by-products during the reaction of Scheme 1 by disproportionation, and may be removed by sublimation or recrystallization. Zr (bdk) ₃ (OR ') can be obtained.

The compound represented by Chemical Formula 2, which is a starting material used to prepare a novel zirconium oxide precursor of the present invention, contains three diketonate ligands and one halogen element (X). Since it can be substituted with an alkoxide ligand, it is possible to obtain a zirconium oxide film which is free from halogen elements and is stable, has excellent volatility, and is advantageous for storage.

In the reactions the reactants are used in stoichiometric equivalent ratios.

The novel zirconium oxide precursor represented by Formula 1 is a stable white solid at room temperature, exhibits relatively high volatility, and has high solubility in organic solvents such as pentane, hexane, diethyl ether, tetrahydrofuran, toluene, and the like. .

The novel zirconium oxide precursors of the present invention are precursors for producing various oxide thin films including zirconium oxide including PZT (lead-zirconium-titanium oxide) thin films, and in particular, metal organic chemical vapor deposition (MOCVD) or atoms widely used in semiconductor manufacturing processes. It is preferably applied to the layer deposition (ALD) process.

The invention can be better understood by the following examples, which are intended for the purpose 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 structures of the reaction products obtained in Examples 1 to 3, respectively, were characterized by ¹ H nuclear magnetic resonance (NMR), carbon atom nuclear magnetic resonance ( ¹³ C NMR) and elemental analysis (EA). a was used, and further determine the characteristic peaks by a fluorine atom nuclear magnetic resonance ⁽¹⁹ F nuclear magnetic resonance, NMR) for the compound containing fluorine.

Preparation of Zirconium Oxide Precursor Material

Example 1: Tris (2,2,6,6-tetramethyl-3,5-heptanedionato) zirconium (IV) trimethylsilanolate [Zr (tmhd) ₃ {OSi (CH ₃ ) ₃ }]

2.15 g of tris {2,2,6,6-tetramethyl-3,5-heptanedionate) zirconium (IV) chloride (3.18 mmol, 1.00) in a flame dried 125 mL Schlenk flask containing 50 mL of pentane. Equivalent weight), and then slowly added 0.34 g of lithium trimethylsilanolate (3.50 mmol, 1.1 equivalents) to the resulting solution to produce a cloudy precipitate. The mixture was stirred for 12 hours at room temperature, filtered and depressurized to remove the solvent from the filtrate to yield a white solid. The resulting solid was sublimed at 90 ° C. under reduced pressure of 10 ⁻² mmHg to give 1.89 g of the title compound as white crystals (yield: 81%).

Example 2: Tris {2,2,6,6-tetramethyl-3,5-heptanedionato) zirconium (IV) 1,1,1,3,3,3-hexafluoro-2-propanolate [ Zr (tmhd) ₃ {OCH (CF ₃ ) ₂ }]

2.32 g of tris {2,2,6,6-tetramethyl-3,5-heptanedionate) zirconium (IV) chloride (3.43 mmol, 1.00) in a flame-dried 125 mL Schlenk flask containing 50 mL of hexane Equivalents) and dissolved, and then 0.72 mL of triethylamine (5.16 mmol, 1.50 equiv) was added to the resulting solution. After cooling the mixed solution to -90 ° C, 0.54 mL of 1,1,1,3,3,3-hexafluoro-2-propanol (5.16 mmol, 1.50 eq) was slowly added to prevent the cloudy precipitation. Generated. The temperature was gradually raised to room temperature, and the solution was stirred for 12 hours, filtered, and then depressurized to remove the solvent from the filtrate to obtain 2.69 g of a high purity white crystal of the title compound (yield: 97%).

Example 3: Tris (2,5-pentanedioneto) zirconium (IV) 1,1,1,3,3,3-hexafluoro-2-propanolate [Zr (acac) ₃ {OCH (CF ₃ ) ₂ }]

1.50 g of tris (2,5-pentanedioneto) zirconium (IV) chloride (3.54 mmol, 1.00 equiv) was dissolved in a 50 mL toluene flame-dried 125 mL Schlenk flask, and then dissolved in the resulting solution. 0.5m mL of 1,1,1,3,3,3-hexafluoro-2-propanol (5.31 mmol, 1.50 equiv) was added slowly at room temperature to produce a cloudy precipitate. The solution was stirred for 12 hours, filtered, and reduced pressure to remove the solvent from the filtrate, and the resulting solid was dissolved in 10 mL of hexane and recrystallized at 0 ° C. to give 1.67 g of a high purity white title compound ( Yield: 85.0%).

Analysis of Zirconium Oxide Precursor Materials

Thermogravimetric analysis / differential thermal analysis (TGA / DTA) method to measure the thermal stability, volatility and decomposition temperature of the zirconium alkoxide complexes of the zirconium oxide precursors synthesized in Examples 1 to 3, respectively Was used. The TGA / DTA method injected nitrogen (N ₂ ) gas at a rate of 100 sccm while warming the product to 800 ° C. at a rate of 10 ° C./min. TGA / DTA graphs of the respective zirconium alkoxide complexes synthesized in Examples 1 to 3 are shown in FIGS. 1 to 3, respectively.

In FIG. 1, Zr (tmhd) ₃ (OSiMe ₃ ) obtained in Example 1 exhibited a mass loss from around 150 ° C., resulting in a sharp mass loss at 250 ° C., and a mass loss of 94.5% or more at 340 ° C. There was no decomposition reaction during the temperature increase, only one step was visible and less than 2.5% of residual material remained. In the TG graph, it was confirmed that T _1/2 (the temperature corresponding to the weight of the original sample when the weight of the original sample reached 1/2 weight) was 296 ° C.

In FIG. 2, Zr (tmhd) ₃ {OCH (CF ₃ ) ₂ } obtained in Example 2 had a mass loss from around 160 ° C., and a rapid mass loss was observed at 250 ° C. FIG. There was no decomposition reaction during the temperature increase and only one step was visible and less than 4.5% residual material remained. In addition, it was confirmed that T _1/2 in the TG graph is 285 ℃.

In FIG. 3, it can be seen that Zr (tmhd) ₃ {OCH (CF ₃ ) ₂ } obtained in Example 3 has a mass reduction from about 100 ° C., resulting in a rapid mass reduction at 200 ° C. FIG. Also at 301 ° C., a mass loss of at least 70.5% was observed, leaving 18.9% of residual material. In addition, it was confirmed that T _1/2 in the TG graph is 247 ℃.

From the results shown in FIGS. 1 to 3, the zirconium alkoxide complex Zr (bdk) ₃ (OR ′) synthesized in the present invention is a conventional zirconium complex Zr (bdk) ₄ (where bdk is tmhd, acac or hfac ), Especially compared to Zr (bdk) ₂ (O ^t Bu) ₂ or Zr (bdk) ₂ (O ⁱ Pr) ₂ , which has high volatility, similar stability, and good solubility in organic solvents It can be seen that ease.

This is because three bidentate donor ligands (bdk) and one alkoxide (OR ') ligand coordinate with zirconium tetravalent ions to meet the coordination number of zirconium ions, making them stable units and increasing volatility. organic groups of (bdk) and alkoxide (OR ') ligands increase solubility in organic solvents, thereby effectively masking oxygen, thereby reducing intermolecular interactions and at the same time increasing affinity for organic solvents. Seems to have been.

As described above, the novel zirconium alkoxide complexes, which are precursors for zirconium oxides of the present invention, are less sensitive to moisture and are advantageous in storage, particularly organometallic chemical vapor deposition (MOCVD) or atomic layer deposition ( As a zirconium precursor used in ALD), there is no inferiority, and thus can be usefully used as a precursor for preparing an oxide thin film including a zirconium oxide including a PZT thin film.

Claims (9)

Zirconium oxide precursor represented by the following formula (1): Formula 1 Where R is an alkyl group of C _1-4 with or without fluorine, and R 'is an alkyl group of C _1-4 with or without fluorine or SiR " ₃ , wherein R" is an alkyl group of C _1-4 )to be. The method of claim 1, A zirconium oxide precursor, wherein R is selected from CH ₃ , CF ₃ , CH (CH ₃ ) ₂ and C (CH ₃ ) ₃ . The method of claim 1, A zirconium oxide precursor, wherein R 'is selected from Si (CH ₃ ) ₃ , CH (CF ₃ ) ₂ and CF ₃ . A method for preparing a zirconium oxide precursor of Formula 1 according to claim 1 comprising reacting a zirconium complex compound represented by Formula 2 with an alkali metal salt of an alcohol represented by Formula 3: Formula 2 Formula 3 Where R is an alkyl group of C _1-4 with or without fluorine, and R 'is an alkyl group of C _1-4 with or without fluorine or SiR " ₃ , wherein R" is an alkyl group of C _1-4 ), X is chlorine, bromine or iodine, and M is Li, Na or K. A method for preparing a zirconium oxide precursor of formula 1 according to claim 1 comprising reacting a zirconium complex represented by formula (2) with an alcohol represented by formula (4) in the presence of a tertiary amine: Formula 2 Formula 4 Where R is an alkyl group of C _1-4 with or without fluorine, and R 'is an alkyl group of C _1-4 with or without fluorine or SiR " ₃ , wherein R" is an alkyl group of C _1-4 ) And X is chlorine, bromine or iodine. The method according to claim 4 or 5, Characterized in that it is carried out at room temperature in a nonpolar solvent. A method of growing a zirconium oxide-containing thin film using the zirconium oxide precursor of any one of claims 1 to 3. The method of claim 7, wherein Wherein the thin film growth process is carried out by metal organic chemical vapor deposition (MOCVD) or atomic layer deposition (ALD). The method of claim 7, wherein Wherein the thin film is a lead-zirconium-titanium oxide (PZT) thin film or a zirconium oxide thin film.