KR20120078025A - Organometallic compounds with silylamine ligand, and method for deposition of a thin-film of metal oxide or silicon-containing metal oxide therefrom - Google Patents

Abstract

PURPOSE: A novel single organic metal precursor compound is provided to enhance volatility and to usefully deposit single metal oxide(TiO_2,ZrO_2,HfO_2), and complex metal oxide(ZrSiOx,HfSiOx) thin film. CONSTITUTION: An organic metal precursor compound for deposition of a metal oxide or metal-silicon oxide thin film is denoted by chemical formula 1. The organic metal precursor compound o chemical formula 1 contains an organic metal precursor of chemical formulas 2 or 3. A thin film deposition method is used for forming metal thin film, metal oxide thin film or metal-silicon oxide thin film using the precursor compound. The thin film is performed by ALD(atomic layer deposition) or MOCVD(metal organic chemical vapor deposition).

Description

Organic metal compounds with silylamine ligands, and method for deposition of a thin-film of metal oxide or silicon-containing metal oxide therefrom}

The present invention relates to an organic metal precursor for depositing a metal oxide film and a metal-silicon oxide film using group 4 compounds applied to a semiconductor device, and a thin film deposition method using the same. More specifically, the organic metal chemical vapor deposition method (MOCVD) And an organometallic precursor compound used for depositing a metal oxide film and a metal-silicon oxide film through Atomic Layer Deposition (ALD) and a method of depositing a thin film using the same.

Recently, as semiconductor circuits have been miniaturized and highly integrated, there is a demand for improving the performance of devices using materials having high dielectric constants such as gate dielectric films of MOS transistors, capacitor dielectric films, and gate dielectric films of nonvolatile memory devices. It is increasing. In particular, products employing high dielectric constant dielectric films such as HfO ₂ as a gate dielectric film and ZrO ₂ and ZrO ₂ / Al ₂ O ₃ as a capacitor dielectric film of DRAM have been released. In addition, Nb ₂ O ₅ , Ta ₂ O ₅ , Research into applying high dielectric materials such as TiO ₂ is underway. Especially recently ZrO ₂ and HfO ₂ There is a growing interest in metal-silicate (HfSiO _x , ZrSiO _x ) thin films doped with silicon in thin films (Thin Solid Films 516 (2008) 1563), which shows that while metal-silicate thin films maintain relatively high dielectric constants, This is because excellent current characteristics and low mobility deterioration have been reported (Applied Surface Science 254 (2008) 6127), and interest in applicability as a dielectric film of an inactive memory device is expected.

In order to form metal-silicate thin films, existing research groups mainly use two different precursor compounds (Hf (NEt ₂ ) ₄ / SiH (NEt ₂ ) ₃ , Hf (NEt ₂ ) ₄ / Si (O ⁿ Bu) ₄ ,). Hf (O ^t Bu) ₄ / SiH ₄ , Hf (NEt ₂ ) ₄ / ^t BuMe ₂ SiOH, Hf (NO ₃ ) ₄ / (O ^t Bu) ₃ SiOH, Hf (NMeEt) ₄ / HSi (NMe ₂ ) ₃ , Hf (NMeEt) ₄ / H ₂ Si (NMe ₂ ) ₂ , Hf (NEt ₂ ) ₄ / Si (NMe ₂ ) ₄ ) has been studied. (Polyhedron 24 (2005) 3066; J. Vac. Sci. Technol. A, Vol. 22, No. 4, 1175; Nucl. Instr. And Meth. In Phys. Res. B 266 (2008) 1824; Journal of Non Crystalline Solids 353 (2007) 1172). However, the method of obtaining a thin film using two precursors is difficult to set a process temperature because the volatility and decomposition temperature between the two precursors are different, and it is difficult to form a film having a uniform composition ratio, especially in a structure having a high aspect ratio. It has the disadvantage of being difficult to maintain the composition. Meanwhile, a single precursor compound containing silicon ((Hf (thd) ₂ (N (SiMe ₃ ) ₂ ) ₂ , Hf (thd) ₂ (OSiMe ₃ ) ₂ , Hf (thd) ₂ (OSi ^t BuMe ₂ ) _2, A study of thin film deposition on metal-silicon oxides using Zr (acac) ₂ (OSiMe ₃ ) ₂ ), Hf (N (SiMe ₂ H) ₂ ) ₄ ) has also been reported (Chem. Vap. Deposition 2002). , 8, No. 4, 171; Inorganica Chimica Acta 362 (2009) 385). However, the single precursor compounds containing silicon known to date have a disadvantage of being solid at room temperature or having low volatility and poor thermal stability, and thus have limitations in the production process.

Therefore, the new types of precursor compounds are capable of depositing ceramic thin films such as high-quality metal oxides and metal oxides containing silicon at a wide process temperature (200 to 450 ° C.), unlike the single precursor compounds containing silicon mentioned above. It needs to be a compound.

Accordingly, the present invention has been made to meet the above-mentioned needs, and by the organometallic chemical vapor deposition (MOCVD) and atomic layer deposition (ALD) it is possible to ensure excellent thin film properties, thickness, step coverage, volatile It is an object of the present invention to provide a single organometallic precursor compound which contains this high, silicon at room temperature liquid phase and which is thermally stable.

In addition, a thin film deposition method for forming a metal oxide or metal-silicon oxide thin film using the organic metal precursor compound (MOCVD, Metal Organic Chemical Vapor Deposition) or Atomic Layer Deposition (ALD) It is another object of the present invention to provide.

In order to achieve the above object, the present invention provides an organometallic precursor compound defined by Formula 1 as an organometallic precursor compound used to deposit a metal oxide or metal-silicon oxide thin film applied to a semiconductor device.

<Formula 1>

In Formula 1, M is one selected from Si, Ge, Ti, Zr, and Hf, L is a halide group, an alkyl group having 1 to 6 carbon atoms, or a cyclopentadienyl group (cyclopentadienyl), and each of R ¹ to R ⁶ is the same. Or alternatively hydrogen, an alkyl group of 1 to 6 carbon atoms or SiR ¹² R ¹³ R ¹⁴ , wherein R ¹² to R ¹⁴ are the same or different and each of hydrogen or an alkyl group of 1 to 6 carbon atoms, x is 0 to 3 Is an integer.

The compound represented by Formula 1 contains silicon because not only does the ligand contain Si in the molecule itself but also contains a silylamine ligand which can be easily oxidized in the oxidizing compound of ozone and water to form a SiO ₂ film. The metal-silicon oxide can be formed by methods such as CVD and ALD.

Among the organometallic precursor compounds represented by Formula 1, L is a halide, in particular, the organometallic precursor compound represented by Formula 2 represented by Cl may increase the reactivity with water by acting as a leaving group having a good Cl group, and during thin film deposition Since Cl has a large electronegativity, the surface adsorption rate can be increased, and thus the growth rate of the thin film can be expected, which is preferable as the organometallic precursor compound.

<Formula 2>

In Formula 2, M, R ¹ to R ⁶ and x are the same as defined above.

Among the organometallic precursor compounds represented by Chemical Formula 1, L is an alkyl group, in particular, an organometallic precursor compound represented by Chemical Formula 3 represented by a methyl group, a non-polar methyl group is introduced to reduce intermolecular attraction, thereby improving volatility, and a boiling point. It is preferred as the organometallic precursor compound by lowering it to enable more smooth precursor supply. In addition, the methyl group has an advantage of increasing the growth rate of the thin film by increasing the adsorption rate on the surface of the thin film by easily reacting with -O- or OH group on the surface of the growing thin film.

<Formula 3>

In Formula 3, M, R ¹ to R ⁶ and x are the same as defined above.

In order to improve the thermal stability among the organometallic precursor compounds represented by Chemical Formula 1 and to increase the process temperature, the organometallic precursor represented by Chemical Formula 4 in which L is substituted with a cyclopentadienyl group, particularly an alkyl cyclopentadienyl Compounds are preferred. Cyclopentadienyl group has the advantage of improving the thermal stability of the precursor through a strong bonding force with the metal to increase the thin film deposition temperature in chemical vapor deposition or atomic layer deposition process.

&Lt; Formula 4 >

In Formula 4, M, R ¹ to R ⁶ and x are the same as defined in Formula 1, and R ⁷ to R ¹¹ are the same as or different from each other, hydrogen, an alkyl group having 1 to 6 carbon atoms, or SiR ¹² R ¹³ R ¹⁴ Wherein R ¹² to R ¹⁴ are the same or different and each is hydrogen or an alkyl group having 1 to 6 carbon atoms.

Specific examples of preferred precursor compounds according to the present invention are as follows.

ClHf (NMeSiMe ₃ ) ₃

ClHf (NEtSiMe ₃ ) ₃

3.MeHf (NMeSiMe ₃ ) ₃

4.MeZr (NEtSiMe ₃ ) ₃

5.MeHf (NEtSiMe ₃ ) ₃

6.Cp (NMe ₂ ) ₂ Hf (NMeSiMe ₃ )

7.Cp (NMe ₂ ) ₂ Zr (NEtSiMe ₃ )

8.Cp (NMe ₂ ) ₂ Hf (NEtSiMe ₃ )

9. (Me ₃ Si) CpHf (NMe ₂ ) ₃

10. (Me ₂ HSi) CpHf (NMe ₂ ) ₃

In the formula, Zr represents zirconium, Hf represents hafnium, Et represents ethyl group, Me represents methyl group, and Cp represents cyclopentadienyl group.

The above-described organometallic precursor compound for metal oxide and metal-silicon oxide thin film deposition represented by Chemical Formula 1 according to the present invention may be prepared by various methods. Among them, for example, it can be represented by Scheme 1 below.

<Scheme 1>

In Scheme 1, M is selected from Si, Ge, Ti, Zr, and Hf, L is selected from a halide group, an alkyl group having 1 to 6 carbon atoms, or a cyclopentadienyl group, and R ³ to R ⁶ are each the same or different. And hydrogen or an alkyl group having 1 to 6 carbon atoms. In addition, AM means lithium (Li) or sodium (Na) metal cation.

In preparing the organometallic precursor compound according to Scheme 1, diethyl ether, tetrahydrofuran or toluene having a weak polarity, and hexane, a nonpolar solvent, may be used as a solvent. have.

An example of a process of preparing the compound of Formula 4 is shown in Scheme 2 below.

<Reaction Scheme 2>

In Scheme 2, M is one selected from Si, Ge, Ti, Zr, and Hf, and R ¹ to R ¹¹ are each the same or different, and are selected from hydrogen or an alkyl group having 1 to 6 carbon atoms.

In preparing the organometallic precursor compound represented by Chemical Formula 4, hexane, which is a nonpolar solvent, or a toluene solvent having a weak polarity, may be used as the solvent.

The thin film deposition method of the present invention is to form a metal thin film, a metal oxide thin film or a metal-silicon oxide thin film on a substrate using the organometallic precursor compound obtained above. In this case, the thin film deposition method is not particularly limited, but the most commonly used method may be atomic layer deposition (ALD) or metal organic chemical vapor deposition (MOCVD).

At this time, when the deposition on the substrate using the metal precursor compound according to the invention, the deposition temperature is preferably 100 ~ 700 ℃. It is possible to adjust the silicon content in the metal silicon oxide film according to the deposition temperature. The delivery method for moving the organometallic precursor compound on the substrate is not particularly limited, but a method of transporting a volatilized gas, a direct liquid injection (DLI) method, or a liquid transport in which the precursor compound is dissolved in an organic solvent and transported The method can be selected and used.

In the present invention, one or more selected from argon (Ar), nitrogen (N ₂ ), helium (He) or hydrogen (H ₂ ) may be used as a transport gas or diluent gas for moving the organometallic precursor compound on a substrate. Can be.

In addition, in the present invention, the organometallic precursor compound may be used to use thermal energy or plasma during deposition on a substrate, or a method of applying a bias on the substrate.

In addition, in the present invention, a reaction for depositing a metal oxide thin film (eg, HfO ₂ , ZrO ₂ , TiO ₂ , SiO ₂ ) or a metal-silicon oxide thin film (eg, HfSiO _x , ZrSiO _x , TiSiO _x ) on a substrate As the gas, water vapor (H ₂ O), oxygen (O ₂ ), ozone (O ₃ ), or the like can be used.

In the present invention, when using the atomic layer deposition process (ALD) it can be formed a thin film using the specific method of the following steps.

(A) heating the organometallic precursor compound to a source temperature of 20 ° C. to 200 ° C. or using a liquid transfer device to transfer the organometallic precursor compound of the present invention into the deposition chamber;

(B) adsorbing the transferred organometallic precursor compound on a substrate to form a precursor layer on the substrate for 0.1 seconds to 1 minute;

(C) removing excess precursor that is not adsorbed onto the substrate using an inert gas;

(D) a precursor layer formed on the substrate for a time within 0.1 seconds to 1 minute of the reaction gas or a mixture gas diluted with the inert gas to form a metal oxide thin film or a metal-silicon oxide thin film on the substrate. Reacting with each other to form a metal oxide thin film or a metal-silicon oxide thin film and a byproduct; And

(E) injecting an inert gas into the chamber to remove excess reaction gas and generated byproducts;

Thin film deposition method characterized in that to form a thin film by repeating the cycle in a cycle (cycle).

In this case, the cycle may be generally performed 10 to 1000 times, preferably 100 to 600 times.

The organometallic precursor compound for depositing a metal oxide and metal-silicon oxide thin film according to the present invention is an organic metal compound having excellent thermal stability, present as a liquid at room temperature, and having high volatility, and is used as a precursor of an organic metal chemical vapor deposition method or an atomic layer deposition method. It can be usefully used to deposit a single metal oxide (TiO ₂ , ZrO ₂ , HfO ₂ ), a composite metal oxide (ZrSiO _x , HfSiO _x ) thin film.

1 shows TGA graphs of hafnium organometallic precursor compounds prepared in Examples 1, 2, 3, 5, 6, 8, 9 and 10.
FIG. 2 shows TGA graphs of zirconium organometallic precursor compounds prepared in Examples 4 and 7. FIG.
3 is a graph showing the deposition rate of the thin film according to the precursor injection temperature during the reaction between the organometallic precursor compounds of Example 6, Example 8 and Example 9 and ozone according to the precursor temperature.
FIG. 4 is a graph showing the deposition rates of the organometallic precursor compounds and the ozone injection time when the organometallic precursor compounds of Example 6, Example 8, and Example 9 react with ozone.
FIG. 5 is a graph showing deposition rates of thin films according to substrate temperature when the organometallic precursor compounds of Example 6, Example 8, and Example 9 react with ozone.
6 is a graph showing the deposition rate of the thin film according to the organometallic precursor injection time during the reaction between the organometallic precursor compounds and water of Example 8 and Example 9.
FIG. 7 is a graph showing thin film deposition rate according to substrate temperature when the organometallic precursor compounds of Example 8 and Example 9 react with water.

Hereinafter, the organometallic precursor compound for depositing the metal oxide and the metal-silicon oxide thin film and the thin film deposition method according to the present invention will be described in more detail with reference to the following examples and experimental examples. It is only presented, the present invention is not limited to the following examples and experimental examples.

< Example 1 > ClHf ( NMeSiMe ₃ ) ₃ Manufacturing

27.7 g (0.1 mol) of n-BuLi 2.5M sol in Hexane was weighed in a 250 mL flask, and diluted with 80 mL of hexane. 11 g (0.1 mol) of methylaminotrimethylsilane was added to the solution at low temperature (- Add slowly with stirring at 10 ^o C) and raise the temperature to room temperature and stir for 10 to 11 hours. Add 8 g (0.025 mol) of hafnium chloride (Hafnium (IV) chloride, HfCl ₄ ) at room temperature and reflux for 12 to 13 hours using a reflux condenser. After the reaction, the resulting solution was filtered under reduced pressure to remove all solvents, and the remaining viscous colorless liquid was distilled under reduced pressure to give 8.6 g (yield: 58.1%) of colorless solid ClHf (NMeSiMe ₃ ) ₃ .

Boiling Point (b.p): 138 ° C at 0.325 torr.

¹ H-NMR (C ₆ D ₆ ): δ 0.246 ([( CH ₃ ) ₃ SiCH ₃ N] ₄ -Hf, s, 36H),

δ 3.029 ([(CH ₃ ) ₃ Si CH ₃ N] ₄ -Hf, s, 12H),

¹³ C-NMR (C ₆ D ₆ ): δ 0.251 ([( C H ₃ ) ₃ SiCH ₃ N] ₄ -Hf),

δ 32.264 ([(CH ₃ ) ₃ Si C H ₃ N] ₄ -Hf),

< Example  2> ClHf ( NEtSiMe ₃ ) ₃ Manufacturing

Example 1, in the same way N - ethyl-l, l-trimethyl-silane amine (N -ethyl-1,1,1-trimethylsilanamine) using ivory-colored solid compound _{ClHf (NEtSiMe 3) 3 23.82g (} crude yield: 95.28%).

Sublimation point: 122 ℃ at 0.2 torr.

¹ H-NMR (C ₆ D ₆ ): δ 0.307 ([N (CH ₂ CH ₃ ) (Si (C H ₃ ) ₃ )]-Hf, s, 36H),

δ 1.237 ([N (CH ₂ C H ₃ ) (Si (CH ₃ ) ₃ )]-Hf, t, 12H),

δ 1.237 ([N (C H ₂ CH ₃ ) (Si (CH ₃ ) ₃ )]-Hf, q, 8H).

¹³ C-NMR (C ₆ D ₆ ): δ 2.844 ([N (CH ₂ CH ₃ ) (Si ( C H ₃ ) ₃ )]-Hf),

δ 21.043 ([N (CH ₂ C H ₃ ) (Si (CH ₃ ) ₃ )]-Hf),

δ 40.005 ([N ( C H ₂ CH ₃ ) (Si (CH ₃ ) ₃ )]-Hf).

< Example  3> MeHf ( NMeSiMe ₃ ) ₃ Manufacturing

48.0 ml (0.120 mol) of n-BuLi are diluted in 100 ml of normal hexane (n-hexane, C ₆ H ₁₄ ), and then N -methyl-1,1,1-trimethylsilaneamine ( N -methyl-1, 12.8 g (97%, 0.120 mol) of 1,1-trimethylsilanamine) is slowly added under an Acetone / CO ₂ (s) bath, and the mixed solution is slowly raised to room temperature and stirred for 6 hours. (Solution A) Add 12.8 g (0.0340 mol) of HfCl ₄ to another flask, and add 50 ml of diethylether (C ₄ H ₁₀ O) and tetrahydrofuran (terahydrofuran, C ₄ ) under Acetone / CO ₂ (s) bath. H ₈ O) 50ml was added slowly and stirred at low temperature for 1 hour. Solution A is added to this mixed solution at low temperature, followed by stirring for one day. (Solution B)

After one day, 32.5 ml (0.0520 mol) of MeLi (methyllithium, CH ₃ Li) was added to Solution B in an acetone / CO ₂ (s) bath, and the solution was then stirred at room temperature for 3 hours.

After completion of the reaction, the solvent and volatile side reactions were removed under reduced pressure, extracted with normal hexane (n-hexane, C ₆ H ₁₄ ), and the solution layer obtained by filtration using a glass filter was removed. To get a yellow liquid. This solid was distilled off and 6.38 g (yield: 31.9%) of MeHf (NMeSiMe ₃ ) _{3 as} a colorless liquid compound was obtained.

Boiling Point (b.p): 86 ° C at 0.23 torr.

¹ H-NMR (C ₆ D ₆ ): δ 0.199 ([NCH ₃ (Si (C H ₃ ) ₃ )]-Hf, s, 27H),

δ 0.308 (C H ₃ -Hf, s, 3H),

δ 2.922 ([NC H ₃ (Si (CH ₃ ) ₃ )]-Hf, t, 9H),

¹³ C-NMR (C ₆ D ₆ ): δ 0.023 ([NCH ₃ (Si ( C H ₃ ) ₃ )]-Hf),

δ 28.485 ([N C H ₃ (Si (CH ₃ ) ₃ )]-Hf),

δ 41.661 (CH ₃ -Hf).

< Example  4> MeZr ( NEtSiMe ₃ ) ₃ Manufacturing

Example 3 In the same manner as with ZrCl ₄ 5g (0.0215mol) and N - ethyl-l, l by using trimethylsilane amine (N -ethyl-1,1,1-trimethylsilanamine) 7.55g (0.0644mol) 2.1 g (yield: 21.4%) of white solid compounds MeZr (NEtSiMe ₃ ) ₃ were obtained.

Sublimation point: 37 ~ 40 ℃ at 0.25 torr.

¹ H-NMR (C ₆ D ₆ ): δ 0.192 ([N (CH ₂ CH ₃ ) (Si (C H ₃ ) ₃ )]-Zr, s, 27H),

δ 0.319 (C H ₃ -Zr, s, 3H),

δ 1.151 ([N (CH ₂ C H ₃ ) (Si (CH ₃ ) ₃ )]-Hf, t, 9H),

δ 3.472 ([N (C H ₂ CH ₃ ) (Si (CH ₃ ) ₃ )]-Hf, q, 4H).

< Example  5> MeHf ( NEtSiMe ₃ ) ₃ Manufacturing

N - ethyl-l, l-trimethyl-silane amine (N -ethyl-1,1,1-trimethylsilanamine) synthesized in the same manner as in Example 3 using 5.49g (0.0468mol) of white solid compound MeHf (NEtSiMe ₃ ) ₃ 3.1 g (yield: 36.6%) was obtained.

Sublimation point: 44 ~ 46 ℃ at 0.43 torr.

¹ H-NMR (C ₆ D ₆ ): δ 0.230 ([N (CH ₂ CH ₃ ) (Si (C H ₃ ) ₃ )]-Hf, s, 27H),

δ 0.297 (C H ₃ -Hf, s, 3H),

δ 1.183 ([N (CH ₂ C H ₃ ) (Si (CH ₃ ) ₃ )]-Hf, t, 9H),

δ 3.388 ([N (C H ₂ CH ₃ ) (Si (CH ₃ ) ₃ )]-Hf, q, 4H).

¹³ C-NMR (C ₆ D ₆ ): δ 2.076 ([N (CH ₂ CH ₃ ) (Si ( C H ₃ ) ₃ )]-Hf),

δ 21.107 ([N (CH ₂ C H ₃ ) (Si (CH ₃ ) ₃ )]-Hf),

δ 36.730 ([N ( C H ₂ CH ₃ ) (Si (CH ₃ ) ₃ )]-Hf),

delta 39.338 (CH ₃ -Hf).

< Example  6> Cp ( NMe ₂ ) ₂ Hf ( NMeSiMe ₃ Manufacturing

After quantifying 75.16 g (0.2 mol) of CpHf (NMe ₂ ) ₃ in a 250 mL flask, add 100 mL of toluene and dilute it, while stirring at low temperature (-10 ^o C), 31 g of methylamino-trimethylsilane (0.3 g) mol) was added slowly with stirring at low temperature (-10 ℃) and the temperature was raised to room temperature to reflux using a reflux condenser for 3 days. After the reaction was carried out under reduced pressure to remove the solvent and the volatile side reaction material and distilled under reduced pressure to obtain 58.7g (yield: 67.7%) of Cp (NMe ₂ ) ₂ Hf (NMeSiMe ₃ ).

Boiling Point (b.p): 99 ℃ at 0.310 torr.

Density: 1.425g / ml at 25 ℃

¹ H-NMR (C ₆ D ₆ ): δ 0.151 ([( CH ₃ ) ₃ SiCH ₃ N] -Hf, s, 9H),

δ 2.711 ([(CH ₃ ) ₃ Si CH ₃ N] ₄ -Hf, s, 3H),

δ 2.951 ([( CH ₃ ) ₂ N] ₂ -Hf, s, 12H),

δ 6.035 (( C ₅ H ₅ ) -Hf, s, 5H).

¹³ C-NMR (C ₆ D ₆ ): δ 0.803 ([( C H ₃ ) ₃ SiCH ₃ N] -Hf),

δ 31.521 ([(CH ₃ ) ₃ Si C H ₃ N] -Hf),

δ 45.594 ([( C H ₃ ) ₂ N] ₂ -Hf),

δ 110.551 (( C ₅ H ₅ ) -Hf).

< Example  7> Cp ( NMe ₂ ) ₂ Zr ( NEtSiMe ₃ Manufacturing

_{CpZr (NMe 2) 3 11.87g (} 0.0411mol) and N - performed using l, l-ethyl trimethylsilane amine (N -ethyl-1,1,1-trimethylsilanamine) 9.65 g (0.0823 mol) Example 5.42 g (yield: 36.5%) of a yellow liquid compound Cp (NMe ₂ ) ₂ Zr (NEtSiMe ₃ ) was obtained by synthesis in the same manner as in 6.

Boiling Point (b.p): 110-120 ° C at 0.34 torr.

Density: 1.227g / ml at 25 ℃

¹ H-NMR (C ₆ D ₆ ): δ 0.148 ([N (CH ₂ CH ₃ ) (Si (C H ₃ ) ₃ )]-Zr, s, 9H),

δ 1.121 ([N (CH ₂ C H ₃ ) (Si (CH ₃ ) ₃ )]-Zr, t, 3H),

δ 2.874 ([N (C H ₃ ) ₂ ] -Zr, s, 12H),

δ 3.002 ([N (C H ₂ CH ₃ ) (Si (CH ₃ ) ₃ )]-Zr, q, 2H),

δ 6.057 ((C ₅ H ₅ ) -Zr, s, 5H),

¹³ C-NMR (C ₆ D ₆ ): δ 2.033 ([N (CH ₂ CH ₃ ) (Si ( C H ₃ ) ₃ )]-Zr),

δ 21.215 ([N (CH ₂ C H ₃ ) (Si (CH ₃ ) ₃ )]-Zr),

δ 40.858 ([N ( C H ₂ CH ₃ ) (Si (CH ₃ ) ₃ )]-Zr),

δ 45.436 ([N ( C H ₃ ) ₂ ] -Zr),

δ 110.737 (( C ₅ H ₅ ) -Zr).

< Example  8> Cp ( NMe ₂ ) ₂ Hf ( NEtSiMe ₃ Manufacturing

Example 6 Method to _{CpHf (NMe 2) 3 33.82g (} 0.09mol) and N, such -ethyl -1, 1, 1-trimethylsilyl amine (N -ethyl-1,1,1-trimethylsilanamine) 21.106g (0.18 mol) was reacted to give 24.4 g (yield: 61%) of a viscous yellow liquid compound, Cp (NMe ₂ ) ₂ Hf (NEtSiMe ₃ ).

Boiling Point (b.p): 91 ° C at 0.25torr.

Density: 1.504g / ml at 25 ℃

¹ H-NMR (C ₆ D ₆ ): δ 0.162 ([(C H ₃ ) SiN (C ₂ H ₅ )]-Hf, s, 9H),

δ 1.110 ([(CH ₃ ) SiN (CH ₂ C H ₃ )]-Hf, t, 3H),

δ 2.919 ([(C H ₃ ) ₂ N] ₂ -Hf, s, 12H),

δ 3.067 ([(CH ₃ ) SiN (C H ₂ CH ₃ )]-Hf, q, 2H),

δ 6.045 ([(C ₅ H ₅ )]-Hf, s, 5H).

¹³ C-NMR (C ₆ D ₆ ): δ 2.157 ([(CH ₃ ) ₃ SiN (C ₂ H ₅ )]-Hf),

δ 21.361 ([(CH ₃ ) ₃ SiN (CH ₂ C H ₃ )]-Hf),

δ 40.775 ([(CH ₃ ) ₃ SiN ( C H ₂ CH ₃ )]-Hf),

δ 45.580 ([( C H ₃ ) ₂ N] ₂ -Hf),

δ 110.616 (( C ₅ H ₅ ) -Hf).

< Example  9> ( Me ₃ Si ) CpHf ( NMe ₂ ) ₃ Manufacturing

21.2 g (59.7 mmol) of tetrais-dimethylamino hafnium was quantified in a 250 mL flask, diluted with 100 mL of hexane, and diluted with trimethylsilylcyclopentadiene while stirring at low temperature (-10 ° C). 8.7g (60 mmol) of tri-mtehylsilyl-cyclopentadiene) was added slowly and slowly raised to room temperature and stirred for about 15 hours to complete the reaction.The solvent and volatile side reactions were removed by vacuum, and the remaining pale yellow liquid was distilled under reduced pressure. 21.1 g (yield 78.9%) of (Me ₃ Si) CpHf (NMe ₂ ) _{3 as a} yellow viscous liquid compound was obtained.

Boiling Point (b.p): 88 ° C at 0.309 torr.

Density: 1.3995g / ml at 25 ℃

¹ H-NMR (C ₆ D ₆ ): δ 0.266 ([(C H ₃ ) ₃ SiC ₅ H ₄ ] -Hf, s, 9H),

δ 2.975 ([(C H ₃ ) ₂ N] ₃ -Hf, s, 18H),

δ 6.261, 6.253 ([(CH ₃ ) ₃ SiC ₅ H ₄ ] -Hf, d, 4H),

¹³ C-NMR (C ₆ D ₆ ): δ 0.233 ([( C H ₃ ) ₃ SiC ₅ H ₄ ] -Hf),

δ 45.267 ([( C H ₃ ) ₂ N] ₃ -Hf),

δ 114.068, 117.460, 121.387 ([(CH ₃ ) ₃ Si C ₅ H ₄ ] -Hf).

< Example  10> ( Me ₂ HSi ) CpHf ( NMe ₂ ) ₃ Manufacturing

15.0 g (42 mmol) of tetrais-dimethylamino hafnium and 5.2 g (42 mmol) of dimethylsilylcyclopentadiene were prepared in the same manner as in Example 9. 14.7 g (yield: 80.8%) of compound (Me ₂ HSi) CpHf (NMe ₂ ) ₃ was obtained.

Boiling Point (b.p): 82 ~ 85 ℃ at 0.244 torr.

¹ H-NMR (C ₆ D ₆ ): δ 0.280 ([(C H ₃ ) ₂ HSiC ₅ H ₄ ] -Hf, s, 6H),

δ 2.984 ([(C H ₃ ) ₂ N] ₃ -Hf, s, 18H),

δ 4.678 ([(CH ₃ ) ₂ H SiC ₅ H ₄ ] -Hf, m, 1H),

δ 6.279, 6.240 ([(CH ₃ ) ₂ HSiC ₅ H ₄ ] -Hf, d, 4H),

¹³ C-NMR (C ₆ D ₆ ): δ -2.764 ([( C H ₃ ) ₂ HSiC ₅ H ₄ ] -Hf),

δ 45.119 ([( C H ₃ ) ₂ N] ₃ -Hf),

δ 114.353, 117.550 ([(CH ₃ ) ₂ HSi C ₅ H ₄ ] -Hf).

< Experimental Example  1>

TGA graph of the hafnium organometallic precursor compounds prepared in Examples 1, 2, 3, 5, 6, 8, 9 and 10 among the above-described embodiments is shown. A TGA graph of the zirconium organometallic precursor compounds prepared in Example 4 and Example 7 is shown in FIG. 2.

As can be seen from the TGA graph, the novel organometallic precursor compounds of the present invention show sufficient volatility and thermal stability for chemical vapor deposition (CVD) or atomic layer deposition (ALD). In addition, it can be seen that it has a higher thermal stability than the existing cyclopentadiene-tris-dimethylamido metal compound.

< Experimental Example  2>

Film formation evaluation by an atomic layer deposition (ALD) process was performed using the precursor compounds of Examples 6, 8 and 9 among the novel hafnium precursors according to the present invention. Ozone was used as the oxidizing agent and argon, an inert gas, was used for purging purposes. Injecting the precursor, argon, ozone and argon was one cycle and the deposition was carried out on a hydrofluoricated Si wafer.

The deposited film was measured by an ellipsometer (Ellipsometer) and the thickness was confirmed by using the FESEM. The silicon content in the film and the impurity contents such as carbon and nitrogen were measured by X-ray photoelectron spectroscopy (XPS) depth profile analysis.

The deposition conditions in the specific film formation evaluation are shown in Table 1. In order to confirm the ALD growth characteristics, the conditions were divided by precursor temperature (Experimental Example A), precursor and ozone injection time (Experimental Example B), and substrate temperature (Experimental Example C).

In Experimental Example A, in the case of Cp (NMe ₂ ) ₂ Hf (NMeSiMe ₃ ), the precursor temperature was changed to 100-120 ° C. At this time, the injection time of the precursor and ozone was fixed at 5 seconds / 3 seconds and the substrate temperature was fixed at 325 ° C. It was. The (Me ₃ Si) CpHf (NMe ₂ ) ₃ changed the precursor temperature to 80 to 100 ° C., and the injection time of the precursor and ozone at this time was fixed at 5 seconds / 3 seconds and the substrate temperature at 275 ° C.

Experimental Example B fixed the precursor temperature of Cp (NMe ₂ ) ₂ Hf (NMeSiMe ₃ ), Cp (NMe ₂ ) ₂ Hf (NEtSiMe ₃ ) at 100 ° C., the substrate temperature at 325 ° C., and the injection time of the precursor and ozone was Cp. In the case of (NMe ₂ ) ₂ Hf (NMeSiMe ₃ ) 1 to 20 seconds / 1 to 8 seconds, Cp (NMe ₂ ) ₂ Hf (NEtSiMe ₃ ) was changed to 1 to 15 seconds / 1 to 10 seconds. (Me ₃ Si) CpHf (NMe ₂ ) ₃ fixed the precursor temperature at 100 ° C., the substrate temperature at 275 ° C., and the ozone injection time at 3 seconds, and changed the precursor injection time to 1 to 15 seconds.

Experimental Example C is an experiment for confirming the growth characteristics according to the substrate temperature Cp (NMe ₂ ) ₂ Hf (NMeSiMe ₃ ), Cp (NMe ₂ ) ₂ Hf (NEtSiMe ₃ ), (Me ₃ Si) CpHf (NMe ₂ ) ₃ The precursor temperature and the precursor and ozone injection time were fixed at 100 ° C., 5 seconds, and 3 seconds, respectively. In the case of Cp (NMe ₂ ) ₂ Hf (NMeSiMe ₃ ) and Cp (NMe ₂ ) ₂ Hf (NEtSiMe ₃ ), the substrate temperature was changed to 225 ~ 390 ° C., and the deposition of (Me ₃ Si) CpHf (NMe ₂ ) ₃ was performed. The temperature evaluated the deposition characteristics in the substrate temperature range of 200 ~ 370 ℃. Deposition rate results of Experimental Examples A, B, and C are shown in FIGS. 3 to 5. In addition, the silicon content in the film according to deposition temperature is shown in Table 2.

Deposition conditions Experimental Example A Precursor Temperature Experimental Example B Injection Time Experimental Example C By Substrate Temperature Precursor temperature
(℃) Precursor / Ozone Injection Time (sec) Substrate temperature
(℃) Precursor temperature
(℃) Precursor / Ozone Injection Time (sec) Substrate temperature
(℃) Precursor temperature
(℃) Precursor / Ozone Injection Time (sec) Substrate temperature
(℃) Cp (NMe ₂ ) ₂ (Hf (NMeSiMe ₃ ) 100-120 5/3 325 100 1-20 / 1-8 325 100 5/3 225-390 Cp (NMe ₂ ) ₂ Hf (NEtSiMe ₃ ) 100 5/3 325 100 1-15/1-10 325 100 5/3 225-390 (Me ₃ Si) CpHf (NMe ₂ ) ₃ 80-100 5/3 275 100 1 ~ 15/3 275 100 5/3 200-370

Deposition Result-Silicon Content Deposition Temperature (℃)
sauce 250 275 300 325 350 390 Cp (NMe ₂ ) ₂ Hf (NMeSiMe ₃ ) Si (at%) 10.5 - 10.9 - 11.1 10.4 Si / (Hf + Si) 0.32 - 0.31 - 0.31 0.27 Cp (NMe ₂ ) ₂ Hf (NEtSiMe ₃ ) Si (at%) 11.1 - 11.1 - 12.9 11.2 Si / (Hf + Si) 0.35 - 0.35 - 0.36 0.31 (Me ₃ Si) CpHf (NMe ₂ ) ₃ Si (at%) 9.6 9.9 - 11.3 10.6 - Si / (Hf + Si) 0.32 0.31 - 0.34 0.33 -

Film deposition was performed using Cp (NMe ₂ ) ₂ Hf (NEtSiMe ₃ ) and (Me ₃ Si) CpHf (NMe ₂ ) ₃ precursor compounds and ozone as deposition conditions of Table 1, and the deposition rate results for each condition are shown in FIG. 3. It is represented by -5.

3 shows the results of the deposition rate of Experimental Example A, the Cp (NMe ₂ ) ₂ Hf (NMeSiMe ₃ ) was confirmed that the average deposition rate of 0.63 Å / cycle in the entire 100 ~ 120 ℃ section, ALD growth It can be seen that the characteristics. In the case of (Me ₃ Si) CpHf (NMe ₂ ) ₃ , it was confirmed that the deposition rate was 0.73 Å / cycle at a temperature of 90 ° C. or higher, and ALD growth was observed at 90 ° C. or higher.

4 shows the deposition rate results of Experimental Example B. The graph on the left shows growth characteristics by precursor injection time and on the right by ozone injection time. First, the deposition characteristics of the precursor injection time were confirmed. It can be seen that all three precursors used in the deposition experiments exhibited a constant deposition rate at an injection time of 5 seconds or more. Cp of (NMe _{2) 2} Hf For (NMeSiMe ₃₎ average _{0.66Å / cycle, Cp (NMe 2} ) 2 average of _{0.63Å / cycle, (Me 3 Si} ) for _{Hf (NEtSiMe 3) CpHf (NMe} 2) 3 When it can be confirmed through Figure 2 that shows a constant deposition rate of 0.73 Å / cycle, which confirms that the precursor is ALD growth.

Depending on the injection time of ozone, if the injection time is more than 2 seconds, the average Cp (NMe ₂ ) ₂ Hf (NMeSiMe ₃ ) is 0.61Å / cycle, and the average Cp (NMe ₂ ) ₂ Hf (NEtSiMe ₃ ) is 0.59Å / cycle. It was confirmed that it showed a constant deposition rate, which is a result showing that the precursor ALD growth.

5 shows deposition characteristics of substrate temperatures. _{Cp (NMe 2) 2 Hf (} NMeSiMe 3) and Cp (NMe _{2) 2} was a case of Hf (NEtSiMe ₃₎ the deposition rate across the substrate range of the temperature 225 ~ 390 ℃ beam a tendency to increase slightly, (Me ₃ In the case of Si) CpHf (NMe ₂ ) _3, the change rate of deposition rate was greater than 275 ° C.

Table 2 shows the results of analyzing the element distribution in the film using XPS. In the case of Cp (NMe ₂ ) ₂ Hf (NMeSiMe ₃ ), the content of silicon in the deposited film was about 10.4 ~ 11.1 at% in the range of 250 ~ 390 ℃, and the ratio of silicon in the total cation hafnium and silicon in the film was 0.27. Was found to be 0.32. Cp (NMe ₂ ) ₂ Hf (NEtSiMe ₃ ) showed 11.1 ~ 12.9 at% and the ratio of silicon in the total cation in the membrane was 0.31 ~ 0.36. The content of (Me ₃ Si) CpHf (NMe ₂ ) ₃ in the film grown at 250 ~ 350 ℃ was 9.6 ~ 11.3at%, and the ratio of silicon in the total cation was 0.31 ~ 0.34.

This is further accomplished by using precursor compounds of Cp (NMe ₂ ) ₂ Hf (NMeSiMe ₃ ), Cp (NMe ₂ ) ₂ Hf (NEtSiMe ₃ ) and (Me ₃ Si) CpHf (NMe ₂ ) ₃ containing silicon-containing ligands. Silicon doping effects could be achieved without the use of silicon precursors.

< Experimental Example  3>

Film formation evaluation by an atomic layer deposition (ALD) process was performed using the precursor compounds of Examples 8 and 9 among the novel hafnium precursors according to the present invention. Water was used as the oxidant and inert gas argon was used for purging purposes. Injection of the precursor, argon, water and argon was made into one cycle and deposition was carried out on a hydrofluoricated Si wafer.

The deposited film was measured by an ellipsometer (Ellipsometer) and the thickness was confirmed by using the FESEM. The silicon content in the film and the impurity contents such as carbon and nitrogen were measured by X-ray photoelectron spectroscopy (XPS) depth profile analysis.

The deposition conditions in the specific film formation evaluation are shown in Table 3. Experimental Example A fixed the (Me ₃ Si) CpHf (NMe ₂ ) ₃ precursor temperature at 100 ° C., the substrate temperature at 325 ° C., and the water injection time at 0.5 seconds, and changed the precursor injection time to 1 to 15 seconds. Experimental Example B is an experiment for confirming the growth characteristics of each substrate temperature, the precursor temperature, the precursor and water injection time is fixed at 100 ℃, 5 seconds, 0.5 seconds, respectively, and the deposition temperature in the substrate temperature range of 225 ~ 390 ℃ Evaluated. The deposition rate results of Experimental Examples A and B are shown in FIGS. 6 to 7. In addition, the silicon content in the film according to deposition temperature is shown in Table 4.

Deposition conditions Experimental Example A Precursor Injection Time Experimental Example B By Substrate Temperature Precursor temperature
(℃) Precursor injection time (sec) Substrate temperature
(℃) Precursor temperature
(℃) Precursor injection time (sec) Substrate temperature
(℃) (Me ₃ Si) CpHf (NMe ₂ ) ₃ ,
Cp (NMe ₂ ) ₂ Hf (NEtSiMe ₃ ) 100 1-15 325 100 5 225-390

Deposition Result-Silicon Content Deposition Temperature (℃)
Silicon content 250 300 350 390 (Me ₃ Si) CpHf (NMe ₂ ) ₃ Si (at%) 4.3 3.5 5.3 6.1 Si / (Hf + Si) 0.13 0.11 0.16 0.18 Cp (NMe ₂ ) ₂ Hf (NEtSiMe ₃ ) Si (at%) 2.7 1.3 4.4 5.7 Si / (Hf + Si) 0.09 0.04 0.13 0.16

Film deposition evaluation was performed using Cp (NMe ₂ ) ₂ Hf (NEtSiMe ₃ ) and (Me ₃ Si) CpHf (NMe ₂ ) ₃ precursor compounds and water as the deposition conditions of Table 3. It is represented by -7.

6 shows the deposition rate results of Experimental Example A, showing growth characteristics according to precursor injection time. It can be seen that both precursors used in the deposition experiments exhibited a constant deposition rate at an injection time of 3 seconds or more. It was confirmed that the average deposition rate of 0.82 Å / cycle for Cp (NMe ₂ ) ₂ Hf (NEtSiMe ₃ ), and 0.706 Å / cycle for (Me ₃ Si) CpHf (NMe ₂ ) ₃ , indicating that the precursor ALD growth is confirmed.

Figure 7 shows the deposition characteristics by substrate temperature. In the case of Cp (NMe ₂ ) ₂ Hf (NEtSiMe ₃ ), the deposition rate tended to increase slightly over the entire substrate temperature of 225 ~ 390 ℃, and 350 ℃ for (Me ₃ Si) CpHf (NMe ₂ ) ₃ . It was confirmed that the average deposition rate was kept constant at 0.63 Å / cycle, which confirms that the precursor grows ALD.

Table 4 shows the results of analyzing the element distribution in the film using XPS. In the case of Cp (NMe ₂ ) ₂ Hf (NEtSiMe ₃ ), the proportion of silicon in the total cation in the membrane was 0.04 ~ 0.16. The content of (Me ₃ Si) CpHf (NMe ₂ ) ₃ in the film grown at 250 ~ 390 ℃ was 3.5 ~ 6.1at%, and the ratio of silicon in the total cation was 0.11 ~ 0.18.

This enabled the use of precursor compounds of Cp (NMe ₂ ) ₂ Hf (NEtSiMe ₃ ) and (Me ₃ Si) CpHf (NMe ₂ ) ₃ with silicon-containing ligands to produce silicon doping effects without the use of additional silicon precursors. .

Claims (17)

An organometallic precursor compound for depositing a metal oxide or metal-silicon oxide thin film defined by Formula 1 below:
<Formula 1>

In Formula 1, M is one selected from Si, Ge, Ti, Zr, and Hf, L is a halide group, an alkyl group having 1 to 6 carbon atoms, or a cyclopentadienyl group (cyclopentadienyl), and each of R ¹ to R ⁶ is the same. Or alternatively hydrogen, an alkyl group of 1 to 6 carbon atoms or SiR ¹² R ¹³ R ¹⁴ , wherein R ¹² to R ¹⁴ are the same or different and each of hydrogen or an alkyl group of 1 to 6 carbon atoms, x is 0 to 3 Is an integer.
The organometallic precursor compound of claim 1, wherein the organometallic precursor compound represented by Formula 1 is an organometallic precursor compound represented by Formula 2 below:
<Formula 2>

In Formula 2, M, R ¹ to R ⁶ and x are the same as defined in Formula 1.
The organometallic precursor compound according to claim 1, wherein the organometallic precursor compound represented by Formula 1 is an organometallic precursor compound represented by Formula 3 below:
<Formula 3>

In Formula 3, M, R ¹ to R ⁶ and x are the same as defined in Formula 1.
The organometallic precursor compound of claim 1, wherein the organometallic precursor compound represented by Formula 1 is an organometallic precursor compound represented by Formula 4 below:
&Lt; Formula 4 >

In Formula 4, M, R ¹ to R ⁶ and x are the same as defined in Formula 1, and R ⁷ to R ¹¹ are the same as or different from each other, hydrogen, an alkyl group having 1 to 6 carbon atoms, or SiR ¹² R ¹³ R ¹⁴ Wherein R ¹² to R ¹⁴ are the same or different and each is hydrogen or an alkyl group having 1 to 6 carbon atoms.
In claim 1, the organometallic precursor compound represented by Formula 1 is ClHf (NMeSiMe ₃ ) ₃ , ClHf (NEtSiMe ₃ ) ₃ , MeHf (NMeSiMe ₃ ) ₃ , MeZr (NEtSiMe ₃ ) ₃ , MeHf (NEtSiMe ₃ ) ₃ , Cp (NMe ₂ ) ₂ Hf (NMeSiMe ₃ ), Cp (NMe ₂ ) ₂ Zr (NEtSiMe ₃ ), Cp (NMe ₂ ) ₂ Hf (NEtSiMe ₃ ), (Me ₃ Si) CpHf (NMe ₂ ) ₃ or (Me Organometallic precursor compound characterized by ₂ HSi) CpHf (NMe ₂ ) ₃ :
In the formula, Zr represents zirconium, Hf represents hafnium, Et represents ethyl group, Me represents methyl group, and Cp represents cyclopentadienyl group.
A process for preparing the organometallic precursor compound of any one of claims 1 to 5, which is prepared by the method of Scheme 1.
<Scheme 1>

In Scheme 1, M, L, and R ¹ to R ⁶ are the same as defined in Chemical Formula 1.
A process for preparing the organometallic precursor compound of any one of claims 1 to 5, which is prepared by the method of Scheme 2:
<Scheme 2>

In Scheme 1, M, L, and R ¹ to R ¹¹ are the same as defined in Chemical Formula 1.
A method of depositing a thin film, comprising: forming a metal thin film, a metal oxide thin film, or a metal-silicon oxide thin film on a substrate using the organometallic precursor compound of any one of claims 1 to 5.
The method of claim 8, wherein the thin film deposition method uses atomic layer deposition (ALD) or metal organic chemical vapor deposition (MOCVD).
The method of claim 8, wherein the deposition temperature is 100 to 700 ° C. when depositing on the substrate using the metal precursor compound.
The thin film deposition method according to claim 8, wherein the silicon content in the metal silicon oxide film is adjusted according to the deposition temperature.
The method of claim 8, wherein the transfer method of moving the organometallic precursor compound on a substrate is a method of transferring a volatilized gas, a direct liquid injection (DLI) method, or a liquid transfer of dissolving the precursor compound in an organic solvent. Thin film deposition method characterized by using a method.
The method of claim 8, wherein the transport gas or diluent gas for moving the organometallic precursor compound on the substrate using at least one selected from argon (Ar), nitrogen (N ₂ ), helium (He) or hydrogen (H ₂ ). Thin film deposition method characterized in that.
The method of claim 8, wherein the organometallic precursor compound is used to deposit heat on the substrate or to apply a bias on the substrate.
The thin film according to claim 8, wherein water vapor (H ₂ O), oxygen (O ₂ ), or ozone (O ₃ ) is used as a reaction gas for depositing a metal oxide thin film or a metal-silicon oxide thin film on a substrate. Deposition method.
The method of claim 9, wherein the atomic layer deposition process (ALD) is used.
(A) heating the organometallic precursor compound to a source temperature of 20 ° C. to 200 ° C. or using a liquid transfer device to transfer the organometallic precursor compound of any one of claims 1 to 5 into the deposition chamber;
(B) adsorbing the transferred organometallic precursor compound on a substrate to form a precursor layer on the substrate for 0.1 seconds to 1 minute;
(C) removing excess precursor that is not adsorbed onto the substrate using an inert gas;
(D) a precursor layer formed on the substrate for a time within 0.1 seconds to 1 minute of the reaction gas or a mixture gas diluted with the inert gas to form a metal oxide thin film or a metal-silicon oxide thin film on the substrate. Reacting with each other to form a metal oxide thin film or a metal-silicon oxide thin film and a byproduct; And
(E) injecting an inert gas into the chamber to remove excess reaction gas and generated byproducts;
Thin film deposition method characterized in that to form a thin film by repeating the cycle in a cycle (cycle).
The method of claim 16, wherein the cycle is performed 10 to 1000 times.

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