JP2007126730A - METHOD FOR PRODUCING ZINC OXIDE FILM BY USING ZINC COMPLEX CONTAINING beta-DIKETONATE HAVING ALKOXYALKYL METHYL GROUP AS LIGAND - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming an industrially preferable zinc oxide film on an article to be film-formed with a simple process. <P>SOLUTION: The production method is directed at forming the zinc oxide film on the article to be film-formed by using a zinc complex and alcohol with a chemical vapor-phase deposition method, and employs a zinc complex containing β-diketonate having an alkoxyalkyl methyl group as a ligand. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a zinc oxide thin film on a film formation target by a chemical vapor deposition method (hereinafter referred to as a CVD method) using a zinc complex and an alcohol.

  In recent years, zinc oxide thin films have been used as transparent electrode thin films for solar cells, liquid crystal display devices, etc., and also for surface acoustic wave devices because the thin films have piezoelectric properties. As a method for obtaining such a zinc oxide thin film, for example, a vacuum deposition method, a sputtering method, a CVD method, and the like have been developed. It has been actively studied.

As a method for producing a zinc oxide thin film by a CVD method, for example, a method using diethyl zinc and dinitrogen monoxide (for example, refer to Non-Patent Document 1) or a method using diethyl zinc and oxygen (for example, Non-Patent Document). 2) is known. However, in these methods, since diethyl zinc that reacts vigorously with dinitrogen monoxide and oxygen must be used, there is a problem that it is difficult to control the reaction. Also known are methods using bis (acetylacetonato) zinc and oxygen (see, for example, Patent Document 1) and methods using bis (acetylacetonato) zinc and ethanol or water (see, for example, Non-Patent Document 3). Although bis (acetylacetonato) zinc used in these methods is a high melting point solid, it is difficult to maintain a constant supply amount and may cause clogging of piping. There was a problem. Therefore, none of the above methods is advantageous as an industrial method for producing a zinc oxide thin film.
Jpn.J.Appl.Phys., 42,568 (2003) Jpn.J.Appl.Phys., 43,1114 (2004) JP 2003-31846 A The 51st Federation of Applied Physics, Proceedings of Lectures, 29p-P10-14 (March 2004)

  An object of the present invention is to provide an industrially suitable method for producing a zinc oxide thin film, which solves the above-described problems and produces a zinc oxide thin film on an object to be formed by a simple method. .

  An object of the present invention is to produce a zinc oxide thin film on an object to be deposited by chemical vapor deposition using a zinc complex and an alcohol, and a β-diketonate having an alkoxyalkylmethyl group as the zinc complex. It solves by the manufacturing method of the zinc oxide thin film characterized by using the zinc complex which uses as a ligand.

  According to the present invention, in a method for producing a zinc oxide thin film on a film formation target by chemical vapor deposition using a zinc complex having an alkoxyalkylmethyl group-containing β-diketonate as a ligand and an alcohol, A method for producing a zinc oxide thin film having excellent film forming characteristics can be provided.

  The metal complex having β-diketonato having an alkoxyalkylmethyl group of the present invention as a ligand is represented by the general formula (1).

(Wherein X represents the general formula (2)

R ^a and R ^b are, for example, carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, and pentyl group. A linear or branched alkyl group of 1 to 5), Y represents a group represented by the general formula (2), or a methyl group, ethyl group, n-propyl group, isopropyl group, n- A linear or branched alkyl group having 1 to 8 carbon atoms such as butyl group, isobutyl group, t-butyl group, pentyl group, hexyl group, heptyl group, octyl group, etc., Z is a hydrogen atom or a methyl group , An ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group or the like, and a linear or branched alkyl group having 1 to 4 carbon atoms. )
Indicated by

  Specific examples of the zinc complex having a β-diketonate having an alkoxyalkylmethyl group used in the present invention as a ligand are represented by, for example, formulas (3) to (10).

  Examples of the alcohol used in the present invention include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, t-butyl alcohol, pentyl alcohol, isopentyl alcohol, and hexyl alcohol. Chain or branched alcohols such as heptyl alcohol, octyl alcohol, nonyl alcohol and decyl alcohol; cyclic alcohols such as cyclopentanol and cyclohexanol; diols such as ethylene glycol and propylene glycol (divalent alcohols) An alcohol substituted with an ether group such as 2-methoxyethanol;

  In the CVD method, it is necessary to vaporize the metal complex for thin film formation. As a method for vaporizing the zinc complex used in the present invention, for example, the zinc complex itself is filled or transported into the vaporization chamber. In addition to the method of vaporization, an appropriate solvent (for example, aliphatic hydrocarbons such as hexane, octane, methylcyclohexane and ethylcyclohexane; aromatic hydrocarbons such as toluene; ethers such as tetrahydrofuran and dibutyl ether) The method (solution method) in which the diluted solution is introduced into the vaporizing chamber with a liquid transfer pump and vaporized can also be used.

  As a vapor deposition method of zinc oxide on a film formation target, it can be performed by a known CVD method, for example, on a film formation target heated with an alcohol vapor gas at a normal pressure or a reduced pressure. Can be used to deposit a zinc oxide thin film. Also, a zinc oxide thin film can be deposited by plasma CVD using the same raw material supply.

  In the case of depositing a zinc oxide thin film using a zinc complex having a β-diketonate having an alkoxyalkylmethyl group of the present invention as a ligand, as the deposition conditions, for example, the pressure in the reaction system is preferably 1 Pa to 200 kPa, more preferably 10 Pa to 110 kPa, film forming object temperature is preferably 50 to 900 ° C., more preferably 100 to 600 ° C., and the temperature for vaporizing the zinc complex is preferably 50 to 250 ° C., more preferably 80 ~ 200 ° C.

  In addition, as a content rate of alcohol vapor gas with respect to the total gas amount at the time of vapor-depositing a zinc oxide complex thin film, Preferably it is 5-90 volume%, More preferably, it is 10-80 volume%.

  Next, the present invention will be specifically described with reference to examples, but the scope of the present invention is not limited thereto.

Reference Example 1 (Synthesis of methyl 2-methoxypropionate)
Sodium methoxide (100.6 g, 1862 mmol) and hexane (300 ml) were added to a 500 ml flask equipped with a stirrer, thermometer and dropping funnel. Next, 300.3 g (1798 mmol) of methyl 2-bromopropionate was slowly added dropwise under ice cooling, and the mixture was reacted for 2 hours with stirring. After completion of the reaction, 300 ml of water was added under water cooling, and the organic layer was separated. Thereafter, the organic layer was washed with water and then dried over anhydrous sodium sulfate. After filtration, the filtrate was distilled under reduced pressure (74 ° C., 12236 Pa) to obtain 97.0 g of methyl 2-methoxypropionate as a colorless liquid (isolation yield: 46%).
The physical properties of methyl 2-methoxypropionate were as follows.

¹ H-NMR (CDCl ₃ , δ (ppm)); 1.41 (3H, d), 3.40 (3H, s), 3.77 (3H, s), 3.90 (1H, q)
MS (m / e); 88, 59, 31, 15

Reference Example 2 (Synthesis of 2-methoxy-6-methyl-3,5-heptanedione (hereinafter referred to as mopd))
Sodium amide (5.15 g, 132 mmol) was added to a 200-ml flask equipped with a stirrer, thermometer and dropping funnel, and the reaction system was purged with argon, and then 80 ml of toluene was added. Next, under water cooling, 12.0 g (139.3 mmol) of 3-methyl-2-butanone was slowly dropped and stirred for 15 minutes, and then 5.65 g (47.8 g) of methyl 2-methoxypropionate synthesized in the same manner as in Reference Example 1. mmol) was added dropwise and allowed to react for 30 minutes with stirring. After completion of the reaction, 50 ml of water was added under ice cooling, and the aqueous layer was separated and neutralized with acetic acid. After the aqueous layer was extracted with ether, the ether extract was washed with water and dried over anhydrous sodium sulfate. After filtration, the filtrate was concentrated, and the concentrate was distilled under reduced pressure (41 ° C., 27 Pa) to obtain 4.25 g of 2-methoxy-6-methyl-3,5-heptanedione as a colorless liquid (isolation yield) : 52%).
The physical properties of 2-methoxy-6-methyl-3,5-heptanedione were as follows.

¹ H-NMR (CDCl ₃ , δ (ppm)); 1.17 (6H, d), 1.30 (0.15H, d), 1.36 (2.85H, d), 2.48 to 2.57 (0.95H, m), 2.59 to 2.73 (0.05H, m), 3.36 (0.15H, s), 3.37 (2.85H, s), 3.71 to 3.78 (1H, m), 3.78 (0.1H, s), 5.81 (0.95H, s), 15.4 ( 0.95H, s)
IR (neat (cm ^-1 )); 2976, 2936, 1607 (br), 1462, 1366, 1328, 1210, 1120, 910, 805
(The peak at 1607 cm ^{-1 is} a peak peculiar to β-diketone.)
MS (m / e); 142, 113, 59, 43

Reference Example 3 (Synthesis of 2-methoxy-3,5-octanedione (hereinafter referred to as mood))
Sodium amide 10.1 g (259 mmol) was added to a 200-ml flask equipped with a stirrer, thermometer and dropping funnel, and the reaction system was purged with argon, and then 100 ml of toluene was added. Next, 14.4 g (167 mmol) of 2-pentanone was slowly added dropwise under water cooling and stirred for 15 minutes, and then 15.0 g (127 mmol) of methyl 2-methoxypropionate synthesized in the same manner as in Reference Example 1 was added dropwise. The mixture was reacted for 1 hour with stirring. After completion of the reaction, 50 ml of water was added under ice cooling, and the aqueous layer was separated and acidified with 2.5 mol / l sulfuric acid. After the aqueous layer was extracted with hexane, the hexane extract was washed with water and dried over anhydrous sodium sulfate. After filtration, the filtrate was concentrated, and the concentrate was distilled under reduced pressure (35 ° C., 20 Pa) to obtain 14.3 g of 2-methoxy-3,5-octanedione as a colorless liquid (isolated yield: 65%) .
The physical properties of 2-methoxy-3,5-octanedione were as follows.

¹ H-NMR (CDCl ₃ , δ (ppm)); 0.97 (3H, m), 1.35 (3H, d), 1.6 to 1.7 (2H, m), 2.29 to 2.34 (1.7H, m), 2.51 (0.3 H, m), 3.36 (3H, s), 3.60 (0.3H, s), 3.74 (1H, q), 5.79 (0.85H, s), 15.3 (0.85H, s)
IR (neat (cm ^-1 )); 2967, 2936, 1608 (br), 1458, 1332, 1210, 1110, 802
(The peak at 1608 cm ^{-1 is} a peak peculiar to β-diketone.)
MS (m / e); 142, 113, 59, 28

Reference Example 4 (Synthesis of bis (2-methoxy-6-methyl-3,5-heptanedionato) zinc (II) (hereinafter referred to as Zn (mopd) ₂ ))
To a 50 ml flask equipped with a stirrer, thermometer and dropping funnel, 6.56 g (34.0 mmol) of 28% sodium methoxide in methanol was added and synthesized in the same manner as in Reference Example 2 under ice cooling. 6.00 g (34.8 mmol) of -methoxy-6-methyl-3,5-heptanedione was gently added dropwise and stirred for 5 minutes. Next, a solution prepared by dissolving 2.26 g (16.6 mmol) of zinc (II) chloride in 20 ml of methanol was slowly added dropwise and reacted for 30 minutes with stirring under ice cooling. After completion of the reaction, methanol was distilled off from the reaction solution under reduced pressure. Thereafter, 20 ml of hexane and 20 ml of water were added, and the organic layer was separated and dried over anhydrous sodium sulfate. After filtration, the filtrate was concentrated, and the concentrate was distilled under reduced pressure (160 ° C., 27 Pa) to give bis (2-methoxy-6-methyl-3,5-heptanedionato) zinc (II) 4.91 as a viscous yellow liquid. g was obtained (isolation yield: 73%).

IR (neat (cm ^-1 )); 2972, 2932, 1582, 1513, 1432, 1333, 1211, 1118, 912, 805, 558
Elemental analysis _{(C 18 H 30 O 6 Zn} ); Carbon: 53.1%, hydrogen: 7.45%, zinc: 16%
(Theoretical value: Carbon: 53.0%, Hydrogen: 7.41%, Zinc: 16.0%)
MS (m / e); 641, 406

Reference Example 5 (Synthesis of bis (2-methoxy-3,5-octandionato) zinc (II) (hereinafter referred to as Zn (mood) ₂ ))
To a 100-ml flask equipped with a stirrer, thermometer and dropping funnel, 4.62 g (24.0 mmol) of 28% sodium methoxide in methanol and 6 ml of methanol were added, and the same method as in Reference Example 6 was carried out under ice cooling. Synthesized 2-methoxy-3,5-octanedione (4.11 g, 23.9 mmol) was slowly added dropwise and stirred for 5 minutes. Next, a solution prepared by dissolving 1.60 g (11.7 mmol) of zinc (II) chloride in 4 ml of methanol was slowly added dropwise and reacted at room temperature for 1 hour with stirring. After completion of the reaction, methanol was distilled off from the reaction solution under reduced pressure. Thereafter, 30 ml of hexane and 30 ml of water were added, and the organic layer was separated and dried over anhydrous sodium sulfate. After filtration, the filtrate was concentrated, and the concentrate was distilled under reduced pressure (160 ° C., 17 Pa) to obtain 4.02 g of bis (2-methoxy-3,5-octandionato) zinc (II) as a yellow liquid ( Isolation yield: 84%).

IR (neat (cm ^-1 )); 2963, 2933, 2874, 2823, 1598, 1522, 1431, 1334, 1211, 1119, 959, 796, 537
Elemental analysis _{(C 18 H 30 O 6 Zn} ); Carbon: 53.1%, hydrogen: 7.45%, zinc: 16%
(Theoretical value: Carbon: 53.0%, Hydrogen: 7.41%, Zinc: 16.0%)
MS (m / e); 406, 347, 113, 59

Examples 1 to 3 (deposition experiment; production of zinc oxide thin film)
Using the zinc complexes (Zn (mopd) ₂ and Zn (mood) ₂ ) obtained in Reference Examples 4 to 5, a vapor deposition experiment by a CVD method was performed to evaluate film formation characteristics.
The apparatus shown in FIG. 1 was used for the evaluation test. The zinc complex 20 in the vaporizer 3 (glass ampoule) is heated and vaporized by the heater 10B, exits the vaporizer 3 along with the helium gas introduced after preheating by the preheater 10A via the mass flow controller 1A. The gas exiting the vaporizer 3 is introduced into the reactor 4 by the mass controller 1B together with helium gas containing alcohol vapor introduced through the cooled alcohol (2 ° C.) 8. The pressure in the reaction system is controlled to a predetermined pressure by opening and closing the valve 6 in front of the vacuum pump, and is monitored by the pressure gauge 5. The central part of the glass reactor has a structure that can be heated by the heater 10C. The zinc complex introduced into the reactor is set in the center of the reactor and thermally decomposed on the surface of the deposition substrate 21 heated to a predetermined temperature by the heater 10C, and a zinc oxide film is deposited on the substrate 21. To do. The gas exiting the reactor 4 is exhausted to the atmosphere via a trap 7 and a vacuum pump.

  The deposition conditions and deposition results (film formation characteristics) are shown in Table 1. In addition, as a substrate for vapor deposition, a rectangular substrate having a size of 7 mm × 40 mm was used.

The results show that a zinc oxide thin film having excellent film forming characteristics can be produced using the zinc complex (Zn (mopd) ₂ and Zn (mood) ₂ ) of the present invention and alcohol. .

  The present invention relates to a method for producing a zinc oxide thin film on a film formation object by a CVD method using a zinc complex having a β-diketonate having an alkoxyalkylmethyl group as a ligand and an alcohol.

It is a figure which shows the structure of the vapor deposition apparatus which manufactures a zinc oxide thin film using a zinc complex and alcohol.

Explanation of symbols

3 vaporizer 4 reactor 8 alcohol 9 cooler 10B vaporizer heater 10C reactor heater 20 raw material zinc complex 21 substrate

Claims (4)

  In a method for producing a zinc oxide thin film on a film formation object by chemical vapor deposition using a zinc complex and an alcohol, a β-diketonate having an alkoxyalkylmethyl group is used as a ligand as the zinc complex. A method for producing a zinc oxide thin film, characterized by using a zinc complex. General formula (1)

(Wherein X represents the general formula (2)

(Wherein R ^a and R ^b represent a linear or branched alkyl group having 1 to 5 carbon atoms), Y represents a group represented by the general formula (2) or carbon A linear or branched alkyl group having 1 to 8 atoms, Z represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. The zinc oxide thin film is produced by chemical vapor deposition using a zinc complex having a β-diketonate having an alkoxyalkylmethyl group represented by formula (II) and an alcohol as a ligand.   A method for producing a zinc oxide thin film by chemical vapor deposition using the solvent solution of the zinc complex according to claim 1 as a zinc supply source.   4. The method for producing a zinc oxide thin film by chemical vapor deposition according to claim 1, wherein the solvent is an aliphatic hydrocarbon, an aromatic hydrocarbon or an ether.

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