Preparation method of zinc oxide film with low carbon content

Abstract

The invention discloses a preparation method of a zinc oxide film with low carbon content, and belongs to the technical field of nanotechnology. According to the method, the continuous and uniform zinc oxide film can be deposited by taking beta-diketone zinc as a precursor and H2O as an oxygen source precursor and utilizing a thermal type atomic layer deposition technology. According to the invention, the precursor without metal carbon bonds is used, so that the problems of potential safety hazard and high carbon content of the precursor in the film deposition process in the prior art are solved; the zinc oxide film obtained through deposition is excellent in uniformity and good in step coverage rate; and in the using process, the device is more convenient, safer and easier to operate.

Description

Technical Field

[0001] The invention relates to a method for preparing a zinc oxide film with low carbon content, belonging to the field of nanotechnology. Background Art

[0002] Zinc oxide (ZnO) is an electron conductor with a wide bandgap (3.37 eV), high exciton binding energy (60 meV), and high mobility. ZnO thin films are also widely used in the semiconductor field as flexible, high-throughput materials. In recent years, with advances in the process of preparing ZnO thin films, their applications in touch panels, sensors, solar cells, thin-film transistors (TFTs), light-emitting diodes (LEDs), electrochemical photovoltaic cells, nanogenerators, and optical waveguides have been extensively studied. To meet the needs of ZnO thin film materials in various fields, a number of methods have been developed to prepare ZnO thin films, including molecular beam epitaxy, magnetron sputtering, spray pyrolysis, pulsed laser deposition (PLD), chemical solution deposition, and metal-organic chemical vapor deposition (MOCVD).

[0003] Atomic layer deposition (ALD) offers significant advantages over these methods. It is a dense thin-film growth technique based on self-limiting surface chemistry. It involves an alternating reaction between a vapor-phase precursor and the substrate surface, depositing the material in atomic layers. This technique can be performed at relatively low temperatures, resulting in highly crystalline films with excellent control over film thickness, composition, and uniformity.

[0004] At present, among the organic zinc precursors, the most representative precursor is diethylzinc (DEZ), which provides a higher growth rate due to its good volatility and high reactivity. DEZ has long been a leading precursor for depositing ZnO thin films. However, DEZ contains metal-carbon bonds, is pyrophoric, and is extremely sensitive to air, posing a significant safety hazard. Furthermore, its deposition temperature ranges from 110°C to 170°C, making it unsuitable for ALD processes requiring stable high temperatures above 200°C. Furthermore, the carbon content in the resulting films is relatively high, leading to the need for a relatively safe ZnO precursor with a low carbon content. Summary of the Invention

[0005] [Technical Issues]

[0006] Precursors containing metal-carbon bonds are extremely sensitive to air and pose a huge safety hazard during use. Excessively high temperatures can cause the precursor to decompose, resulting in a high C element content in the film and reducing the quality of the film. As the size of semiconductor processes becomes smaller, the original technology cannot adapt to the requirements of the new process.

[0007] [Technical solution]

[0008] To address these issues, the present invention utilizes thermal atomic layer deposition (ALD) technology to deposit continuous, uniform zinc oxide thin films using β-diketonates as precursors and H₂O as an oxygen source. This method utilizes a precursor free of metal-carbon bonds, addressing the safety concerns and high carbon content associated with conventional thin film deposition processes. The resulting zinc oxide thin films exhibit excellent uniformity and step coverage, while also being more convenient, safer, and easier to operate.

[0009] The first object of the present application is to provide a method for preparing a low-carbon content zinc oxide film, using β-diketone zinc as a zinc source precursor and H2O as a reducing precursor, and using thermal atomic layer deposition technology to prepare the zinc oxide film.

[0010] In one embodiment, the structural formula of β-diketone zinc is as shown in any one of Formula I, Formula II, and Formula III:

[0011]

[0012] In one embodiment, the β-diketone zinc shown in formula I is a complex Zn(thd)2; the β-diketone zinc shown in formula II is a complex Zn(tmod)2; and the β-diketone zinc shown in formula III is a complex Zn(ibpm)2.

[0013] In one embodiment, a method for preparing a zinc oxide thin film using thermal atomic layer deposition technology includes the steps of:

[0014] (1) placing a Si(100) substrate in a reaction chamber, introducing a vapor-phase zinc source into the reaction chamber in a pulsed manner for deposition, and obtaining a substrate on which the zinc source is deposited;

[0015] (2) Filling the system with inert gas for purging;

[0016] (3) introducing a gaseous oxygen source precursor into the reaction chamber in a pulsed form to react with the zinc source deposited on the substrate;

[0017] (4) Filling the system with inert gas for purging to complete an atomic layer deposition (ALD) growth cycle;

[0018] (5) Repeat steps (1) to (4) to obtain a zinc oxide film.

[0019] In one embodiment, the duration of a single pulse of the gaseous zinc source introduced into the reaction chamber in a pulsed form in step (1) is 1 to 4 seconds; the gaseous zinc source is introduced in a pulsed form in the presence of a carrier gas, and the flow rate of the carrier gas is 150 to 200 sccm; the carrier gas is one of high-purity nitrogen gases.

[0020] In one embodiment, the substrate in step (1) is Si (100), and the substrate needs to be pretreated before entering the reaction chamber to remove impurities and oxide layers on the surface.

[0021] In one embodiment, the duration of a single pulse of the gas-phase zinc source introduced into the reaction chamber in pulse form in step (1) is 1-4 s, preferably 2 s.

[0022] In one embodiment, in step (1), the gaseous zinc source is introduced in a pulsed manner in the presence of a carrier gas, the flow rate of the carrier gas is 150 sccm, and the carrier gas is high-purity nitrogen.

[0023] In one embodiment, the gaseous zinc source in step (1) is obtained by heating a zinc source to vaporize it, and the heating temperature of the zinc source is 120°C.

[0024] In one embodiment, the deposition temperature in step (1) is 150-250°C, preferably 190-210°C.

[0025] In one embodiment, the duration of a single pulse of the oxygen source precursor introduced into the reaction chamber in a pulsed form in step (3) is 0.5 to 2 seconds, preferably 0.8 seconds.

[0026] In one embodiment, the gas-phase oxygen source precursor in step (3) is vacuumed at room temperature.

[0027] In one embodiment, step (5) is repeated 1 to 3000 times.

[0028] The second object of the present invention is to provide a zinc oxide thin film prepared by any of the above methods.

[0029] The third object of the present invention is to provide the application of the above zinc oxide film in the field of integrated circuit preparation or nanomaterials.

[0030] A fourth object of the present invention is to provide a product comprising the zinc oxide film described above; the product includes electronic devices, optoelectronic devices, transparent conductive films, varistors and piezoelectric devices, antibacterial and packaging materials, coatings, and rubber additives.

[0031] A fifth object of the present invention is to provide a method for reducing the carbon content in a zinc oxide film, wherein the zinc oxide film is prepared by thermal atomic layer deposition technology using β-diketone zinc as a zinc source precursor and H2O as a reducing precursor.

[0032] In one embodiment, the structural formula of β-diketone zinc is as shown in any one of Formula I, Formula II, and Formula III:

[0033]

[0034]

[0035] In one embodiment, the growth temperature of the zinc oxide thin film in the thermal atomic layer deposition technology is 150-250°C.

[0036] In one embodiment, a method for preparing a zinc oxide thin film using thermal atomic layer deposition technology includes the steps of:

[0037] (1) placing a Si(100) substrate in a reaction chamber, introducing a vapor-phase zinc source into the reaction chamber in a pulsed manner for deposition, and obtaining a substrate on which the zinc source is deposited;

[0038] (2) Filling the system with inert gas for purging;

[0039] (3) introducing a gaseous oxygen source precursor into the reaction chamber in a pulsed form to react with the zinc source deposited on the substrate;

[0040] (4) Filling the system with inert gas for purging to complete an atomic layer deposition (ALD) growth cycle;

[0041] (5) Repeat steps (1) to (4) several times to obtain a zinc oxide film.

[0042] In one embodiment, the duration of a single pulse of the gaseous zinc source introduced into the reaction chamber in a pulsed form in step (1) is 1 to 4 seconds; the gaseous zinc source is introduced in a pulsed form in the presence of a carrier gas, and the flow rate of the carrier gas is 150 sccm; the carrier gas is one of high-purity nitrogen gases.

[0043] In one embodiment, the duration of a single pulse of the gaseous zinc source introduced into the reaction chamber in a pulsed form in step (1) is 1 to 4 seconds; the gaseous zinc source is introduced in a pulsed form in the presence of a carrier gas, and the flow rate of the carrier gas is 150 sccm; the carrier gas is one of high-purity nitrogen gases.

[0044] In one embodiment, the substrate in step (1) is Si (100), and the substrate needs to be pretreated before entering the reaction chamber to remove impurities and oxide layers on the surface.

[0045] In one embodiment, the duration of a single pulse of the gas-phase zinc source introduced into the reaction chamber in pulse form in step (1) is 1-4 s, preferably 2 s.

[0046] In one embodiment, in step (1), the gaseous zinc source is introduced in a pulsed manner in the presence of a carrier gas, the flow rate of the carrier gas is 150-200 sccm, and the carrier gas is high-purity nitrogen.

[0047] In one embodiment, the gaseous zinc source in step (1) is obtained by heating a zinc source to vaporize it, and the heating temperature of the zinc source is 120°C.

[0048] In one embodiment, the deposition temperature in step (1) is 150-250°C, preferably 190-210°C.

[0049] In one embodiment, the duration of a single pulse of the oxygen source precursor introduced into the reaction chamber in a pulsed form in step (3) is 0.5 to 2 seconds, preferably 0.8 seconds.

[0050] In one embodiment, the gas-phase oxygen source precursor in step (3) is vacuumed at room temperature.

[0051] In one embodiment, step (5) is repeated 1 to 3000 times.

[0052] Beneficial effects of the present invention

[0053] The present invention uses β-diketonate zinc precursors and H2O as an oxygen source precursor, utilizing thermal atomic layer deposition technology to deposit a continuous, uniform zinc oxide film. The present invention utilizes a precursor that contains no metal-carbon bonds, resolving the safety concerns and high carbon content of precursors in conventional thin film deposition processes. The zinc oxide film deposited by the present invention exhibits excellent uniformity and step coverage, and is more convenient, safer, and easier to operate during use. Specifically:

[0054] (1) The β-diketone zinc precursor used in the present invention does not contain metal-carbon bonds, thereby avoiding safety hazards in the preparation process and the problem of high C element content, and improving the deposition quality and effect of the zinc oxide film.

[0055] (2) The method of the present invention can be used to prepare small-sized semiconductors.

[0056] (3) The zinc oxide film deposited by the present invention has excellent uniformity and good step coverage.

[0057] (4) The present invention is more convenient, safer, and easier to operate during use, simplifies the preparation process of the single-element film, and saves costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 This is the H NMR spectrum of the complex Zn(thd)2;

[0059] Figure 2 is the H NMR spectrum of the complex Zn(tmod)2;

[0060] Figure 3 is the carbon magnetic hydrogen spectrum of the complex Zn(tmod)2;

[0061] Figure 4 is the H-NMR spectrum of the complex Zn(ibpm)2;

[0062] Figure 5 is the carbon magnetic hydrogen spectrum of the complex Zn(ibpm)2;

[0063] Figure 6 The surface roughness of the zinc oxide film prepared by the complex Zn(thd)2;

[0064] Figure 7 The surface roughness of the zinc oxide film prepared by the complex Zn(tmod)2;

[0065] Figure 8 The surface roughness of the zinc oxide film prepared by the complex Zn(ibpm)2;

[0066] Figure 9 The zinc oxide film prepared in Example 1 was heated at 200°C under Ar + XPS full spectrum before and after etching for 60 seconds;

[0067] Figure 10 The film prepared in Comparative Example 2 was heated at 200°C under Ar + XPS full spectrum before and after etching for 60 seconds;

[0068] Figure 11 The film prepared in Comparative Example 3 was heated at 200°C under Ar + XPS full spectrum before and after etching for 60 seconds;

[0069] Figure 12 The film prepared in Example 6 was heated at 200°C under Ar + XPS full spectrum before and after etching for 60 seconds;

[0070] Figure 13 The film prepared in Example 7 was heated at 200°C under Ar + Full XPS spectrum before and after etching for 60 seconds. DETAILED DESCRIPTION

[0071] The following describes preferred embodiments of the present invention. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0072] The raw materials used in the embodiment are:

[0073] 3,3-Dimethyl-2-butanone, 2,2-dimethylbutyryl chloride, and methyl trimethylacetate were purchased from MacLean Chemical Reagent Co., Ltd.; the remaining raw materials were all purchased from Sinopharm Chemical Reagent Co., Ltd.

[0074] Preparation method

[0075] 1. The synthetic route of the complex Zn(thd)2 used in the examples is as follows:

[0076]

[0077] 2. The synthetic route of the complex Zn(tmod)2 used in the examples is as follows:

[0078]

[0079] 3. The synthetic route of the complex Zn(ibpm)2 used in the examples is as follows:

[0080]

[0081] Example 1: A method for preparing a zinc oxide film with low carbon content

[0082] 1. Preparation of complex Zn(thd)2

[0083] Preparation of the complex Zn(thd)2, the steps comprising:

[0084] (1) Weigh 4.0 g (100 mmol) of NaOH and add it to a 250 mL round-bottom flask. Add 60 mL of H2O and 60 mL of ethanol and stir to dissolve. Weigh 18.4 g of 2,2,6,6-tetramethyl-3,5-heptanedione (100 mmol) and slowly add it to the NaOH solution using a constant pressure funnel. The solution changes from a colorless transparent solution to a light yellow transparent solution. Stir at room temperature for 5 h to obtain a mixed solution.

[0085] Weigh 6.8 g ZnCl2 (50 mmol) and dissolve it in 60 mL 50% ethanol solution. Slowly add it to the mixed solution using a constant pressure funnel. After adding the ZnCl2 solution, the system quickly produces a white solid and dissolves rapidly. After adding 30 mL, the white solid no longer dissolves. Continue to add the solution until the system gradually changes from a clear liquid to a milky white suspension. Stir at room temperature for 8 h; let it stand, filter to obtain a white solid, and dry it at 90°C for 12 h.

[0086] The dried material was sublimed at 125°C to obtain a white crystalline solid (34.6 g, yield 80%), and the complex Zn(thd)2 was prepared, and its melting range was determined to be 132.1°C to 134.0°C. Figure 1 As shown, 1 H NMR (400MHz, (CD3)2SO, ppm,): δ5.52(s,2H,COCHCO),1.06(s,36H,(CH3)3C).

[0087] The structural formula of the complex Zn(thd)2 is shown below:

[0088]

[0089] 2. Preparation method of zinc oxide film

[0090] A method for preparing a zinc oxide film with a low carbon content, comprising the steps of:

[0091] (1) Si(100) substrate was placed in a reaction chamber; the complex Zn(thd)2 was heated to 125°C to vaporize it and form a vapor-phase zinc source; the vapor-phase zinc source was introduced into the reaction chamber in the presence of a carrier gas (high-purity nitrogen, flow rate of 150 sccm) in a pulsed form (pulse time of 2 s) and deposited at 200°C to obtain a substrate with deposited zinc source;

[0092] (2) After completing a pulse, high-purity nitrogen is used for purging, and the purging time is 2s;

[0093] (3) Vacuuming H2O to vaporize it and form a gaseous oxygen source precursor; the oxygen source precursor is introduced into the reaction chamber in a pulsed form (pulse time is 0.8 s) to undergo a self-limiting reaction with the zinc source deposited on the substrate at 200°C;

[0094] (4) After completing a pulse, high-purity nitrogen is used for purging, and the purging time is 10 seconds;

[0095] (5) Repeat steps (1) to (4) 500 times to obtain a zinc oxide thin film with a thickness of 11.09 nm.

[0096] Example 2: A method for preparing a zinc oxide film with low carbon content

[0097] On the basis of Example 1, the pulse time in step (1) of 2 was changed to 1.5 s, and the remaining steps were consistent with Example 1 to prepare a zinc oxide thin film with a thickness of 7.51 nm.

[0098] Example 3: A method for preparing a zinc oxide film with low carbon content

[0099] On the basis of Example 1, the pulse time in step (3) of step 2 was changed to 0.5 s, and the remaining steps were consistent with Example 1 to prepare a zinc oxide thin film with a thickness of 8.73 nm.

[0100] Example 4: A method for preparing a zinc oxide film with low carbon content

[0101] On the basis of Example 1, the pulse time in step (1) of 2 was changed to 2.5 s, and the remaining steps were consistent with Example 1 to prepare a zinc oxide thin film with a thickness of 11.12 nm.

[0102] Example 5: A method for preparing a zinc oxide film with low carbon content

[0103] On the basis of Example 1, the pulse time in step (3) of step 2 was changed to 1.5 s, and the remaining steps were consistent with Example 1 to prepare a zinc oxide thin film with a thickness of 10.98 nm.

[0104] Comparative Example 1: Changing the substrate material

[0105] On the basis of Example 1, the substrate material is changed to SiO2, and the remaining steps are consistent with Example 1.

[0106] The results showed that no thin film could be produced.

[0107] Comparative Example 2: Changing the oxygen source precursor material

[0108] On the basis of Example 1, O3 was used instead of H2O as the oxygen source precursor, and the remaining steps were consistent with Example 1.

[0109] The results show that a small amount of film thickness appears, about 2nm to 3nm, and the film growth process does not conform to the characteristics of ALD self-limiting growth.

[0110] Comparative Example 3: Changing the oxygen source precursor material

[0111] On the basis of Example 1, MBO was used instead of H2O as the oxygen source precursor, and the remaining steps were consistent with Example 1.

[0112] The results show that a small amount of film thickness appears, about 2nm to 3nm, and the film growth process does not conform to the characteristics of ALD self-limiting growth.

[0113] Example 6: A method for preparing a zinc oxide film with low carbon content

[0114] 1. Preparation of complex Zn(tmod)2·H2O

[0115] Preparation of complex Zn(tmod)2, the steps are as follows:

[0116] In a glove box, NaH (17.6 g, 600 mmol) was weighed into a 500 mL Schelenk bottle, and 360 mL of anhydrous tetrahydrofuran was added; 3,3-dimethyl-2-butanone (52.8 g, 528 mmol) was weighed and added dropwise to the system using a constant pressure funnel. Bubbles were generated during the addition. The mixture was slowly heated to 70°C. After the addition was completed, the system changed from an off-white turbid liquid to a light green color. The reaction was carried out at 70°C for 1 h. During the reaction, the system gradually changed from light green to bright yellow, and the rate of bubble generation in the oil bubble gas accelerated.

[0117] The reaction was continued for 3 hours, the system gradually changed from bright yellow to dark yellow, the rate of bubbles in the oil bubble slowed down and gradually stabilized, the reaction was continued for 16 hours, the rate of bubbles in the oil bubble began to slow down, the reaction was continued for 20 hours, and no bubbles were generated in the oil bubble, and heating was stopped; the upper layer was a dark yellow clear liquid, and the lower layer was a dark gray precipitate. The upper layer of dark yellow clear liquid was filtered through a sand filter tube, and 2,2-dimethylbutyryl chloride (35.4g, 264mmol) was weighed and added dropwise to the yellow clear liquid under an ice bath, quickly producing a white precipitate. After the addition was complete, the solution became a dark yellow turbid liquid. After returning to room temperature, the system gradually changed from dark yellow to light yellow. When the stirring was continued for 4 hours, the color of the system did not change. 27.0mL of concentrated hydrochloric acid was added dropwise under an ice bath, quickly producing a large amount of white precipitate. After the addition was complete, the solution was stirred for 2 hours, and the system gradually separated from the light yellow turbid liquid, with the upper layer being a light yellow clear liquid and the lower layer being a white precipitate. The filtrate was filtered and extracted three times with n-hexane (100 mL × 50 mL × 50 mL), and the organic phases were combined. 40 g of anhydrous sodium sulfate was added to the organic phase, the filtrate was filtered, and the volatile solvent was removed by rotary evaporation to obtain 60 mL of a yellow clear liquid. The yellow clear liquid was evacuated to 4.0 mm Hg and slowly heated. The fraction was distilled under reduced pressure at an oil temperature of 90° C. and a steam temperature of 71° C. to obtain 30 mL of a colorless transparent liquid, i.e., the ligand Htmod was obtained. The purity of the ligand Htmod was verified by gas chromatograph to ensure that the purity of the ligand was above 96%.

[0118] Weigh 4.0g (100mmol) of NaOH into a 250mL round-bottom flask, add 120mL of methanol, and stir until the solid dissolves. Weigh 19.8g of Htmod (100mmol) and slowly add it to the NaOH solution using a constant pressure funnel. The solution changes from a colorless, transparent liquid to a pale yellow, transparent liquid. Stir for 5h. Weigh 14.9g of Zn(NO3)2·6H2O (50mmol) and dissolve it in 60mL of methanol solution and slowly add it to the system. Upon addition of Zn(NO3)2·6H2O, a white solid quickly forms and dissolves rapidly. Continue adding dropwise to 30mL, but the resulting white solid no longer dissolves, the system gradually becomes turbid, and a white precipitate forms. After the addition is complete, the system becomes a milky white suspension. Stir for 8h. Let stand to separate the layers, with the upper layer being a pale yellow clear liquid and the lower layer being a white precipitate. Filter the filtrate. 60 mL of H₂O was added to the filtrate, quickly producing a viscous substance in the lower layer of the clear liquid. 60 mL of n-hexane was added with stirring, dissolving the viscous substance. The system was separated into layers, and the upper n-hexane phase was collected. 20 g of anhydrous sodium sulfate was added and filtered to obtain a pale yellow n-hexane solution. This solution was concentrated to 10 mL and recrystallized at -30°C to yield 18.4 g of colorless crystals, the complex Zn(tmod)₂·H₂O. The yield of the complex Zn(tmod)₂·H₂O was 80%, with a melting range of 71.9°C-73.0°C.

[0119] The H NMR spectrum of Zn(tmod)2·H2O is: 1 HNMR(400MHz,C2D6SO,ppm)δ,0.75(t,3H,CH2CH3),δ1.42(m,2H,((CH3)2CCH2CH3 )), δ1.01(s,6H((CH3)2CCH2CH3)), δ1.06(s,9H((CH3)3C)δ5.47(s,O=C-CH-C=O);

[0120] The NMR carbon spectrum is: 13 C NMR(600MHz,C2D6SO,ppm)tδ200.58(C=O),89.55(O=C-CH-C=O)44.58(-C(CH3)2-CH2-CH3),41.08(-C(CH3) 3), 34.22(-C(CH3)2-CH2-CH3), 28.65(-C(CH3)2-CH2-CH3), 26.12(-C(CH3)3), 9.65(-C(CH3)2-CH2-CH3).

[0121] 2. Preparation of complex Zn(tmod)2

[0122] 85.0 g (178 mmol) of Zn(tmod)2·H2O crystals were added to Schlenk flask A. A separate Schlenk flask, B, was assembled using a U-shaped tube. 40 g of phosphorus pentoxide was added to Schlenk flask B. The crystal mixture in Schlenk flask A was evacuated and slowly heated. At around 85°C, the crystals melted, and the system transformed into a white, turbid liquid. Heating continued to 120°C, and a white, powdery solid slowly began to form on the flask walls. The mixture was then held at this temperature for 12 hours. Throughout this period, the system remained a white, turbid liquid with no significant changes.

[0123] A small amount of liquid appeared in the U-shaped tube around 4 hours, reaching a peak after 10 hours. After 12 hours of heat preservation, the mixture was returned to room temperature. 100 mL of anhydrous n-hexane was added and allowed to stand. After standing, the layers separated, revealing a yellow clear liquid on top and a white precipitate on the bottom. Filtering with a sand filter separated a white powdery solid and approximately 120 mL of a pale yellow clear liquid. The solution was concentrated to 50 mL and recrystallized at -30°C to yield 40.0 g of pale yellow crystals, the complex Zn(tmod)2.

[0124] The yield of the complex Zn(tmod)2 is 49%, and the melting range is 41.8℃-43.0℃.

[0125] The H NMR spectrum of Zn(tmod)2 Figure 2 )for: 1H NMR(400MHz,C2D6SO,ppm)δ,0.73(t,3H,CH2CH3),δ1.44(m,2H,((CH3)2CCH2CH3) ), δ1.02(s,6H((CH3)2CCH2CH3)), δ1.06(s,9H((CH3)3C)δ5.48(s,O=C-CH-C=O);

[0126] Its NMR carbon spectrum ( Figure 3 )for: 13 C NMR(600MHz,C2D6SO,ppm)tδ200.12(C=O),90.86(O=C-CH-C=O)43.85(-C(CH3)2-CH2-CH3),41.09(-C(CH3) 3), 34.22(-C(CH3)2-CH2-CH3), 28.64(-C(CH3)2-CH2-CH3), 26.12(-C(CH3)3), 9.67(-C(CH3)2-CH2-CH3).

[0127] The structural formula of the complex Zn(tmod)2 is shown below:

[0128]

[0129] 3. Preparation method of zinc oxide film

[0130] The zinc oxide film is prepared by replacing the complex Zn(thd)2 with the complex Zn(tmod)2, comprising the steps of:

[0131] (1) Si(100) substrate was placed in a reaction chamber; the complex Zn(tmod)2 was heated to 120°C to vaporize it and form a vapor-phase zinc source; the vapor-phase zinc source was introduced into the reaction chamber in the presence of a carrier gas (high-purity nitrogen, flow rate of 150 sccm) in a pulsed form (pulse time of 4 s) and deposited at 200°C to obtain a substrate with deposited zinc source;

[0132] (2) After completing a pulse, high-purity nitrogen is used for purging, and the purging time is 2s;

[0133] (3) Vacuuming H2O to vaporize it and form a gaseous oxygen source precursor; the oxygen source precursor is introduced into the reaction chamber in a pulsed form (pulse time is 0.8 s) to undergo a self-limiting reaction with the zinc source deposited on the substrate at 200°C;

[0134] (4) After completing a pulse, high-purity nitrogen is used for purging, and the purging time is 10 seconds;

[0135] (5) Repeat steps (1) to (4) 500 times to obtain a zinc oxide thin film with a thickness of 12.03 nm.

[0136] Example 7: A method for preparing a zinc oxide film with low carbon content

[0137] On the basis of Example 6, the pulse time in step (1) of 3 was changed to 3s, and the remaining steps were consistent with Example 1 to prepare a zinc oxide thin film with a thickness of 8.11 nm.

[0138] Example 8: A method for preparing a zinc oxide film with low carbon content

[0139] On the basis of Example 6, the pulse time in step (3) of 3 was changed to 0.5 s, and the remaining steps were consistent with Example 1 to prepare a zinc oxide thin film with a thickness of 7.51 nm.

[0140] Example 9: A method for preparing a zinc oxide film with low carbon content

[0141] On the basis of Example 6, the pulse time in step (1) of 3 was changed to 2.5 s, and the remaining steps were consistent with Example 1 to prepare a zinc oxide thin film with a thickness of 12.10 nm.

[0142] Example 10: A method for preparing a zinc oxide film with low carbon content

[0143] On the basis of Example 6, the pulse time in step (3) of 6 was changed to 1.5 s, and the remaining steps were consistent with Example 1 to prepare a zinc oxide thin film with a thickness of 11.97 nm.

[0144] Example 11: A method for preparing a zinc oxide film with low carbon content

[0145] 1. Preparation of complex 3(Zn(ibpm)2)·2H2O

[0146] The preparation steps of complex 3 (Zn (ibpm) 2) · 2H 2 O are as follows:

[0147] Weigh potassium tert-butoxide (67.2g, 600mmol) in a 1000mL Schelenk bottle, build a constant pressure dropping funnel, add 300mL of DMF to the constant pressure funnel, utilize a vacuum pump to extract the oxygen in the DMF, until DMF no longer emits bubbles, and add it to the Schelenk bottle. Heat to 50°C and stir until the solid is completely dissolved. After dissolution, a light blue turbid solution is presented. Methyl trimethylacetate (42.0g, 3600mmol) is added dropwise. After the addition is completed, a light yellow turbid liquid is presented. Continue to dropwise add 3-methyl-2-butanone (21.0g, 240mmol). After the addition is completed, a bright yellow turbid liquid is presented. After stirring for 4h, the system turns dark brown. Dilute sulfuric acid (290mL deionized water+29mL concentrated sulfuric acid) is added to the system at one time and stirred vigorously. After adding sulfuric acid, a precipitate is rapidly produced. The system slowly changes from dark brown to deep red, and finally quickly changes to bright yellow. The mixture was allowed to stand for stratification, with the upper layer being a bright yellow clear liquid and the lower layer being a white precipitate. The upper layer of light yellow clear liquid was filtered and extracted three times with n-hexane (100 mL × 50 mL × 50 mL). The upper n-hexane phase was separated and 20 g of anhydrous sodium sulfate was added, filtered, and the solvent was removed by rotary evaporation. 60 mL of yellow clear liquid was obtained, which was evacuated to 4.0 mmHg and slowly heated. The fraction was distilled under reduced pressure at an oil temperature of 80°C and a steam temperature of 65°C to obtain 30 mL of colorless transparent liquid. The purity of the ligand Hibpm was verified by gas chromatography to ensure that the purity of the ligand was above 96%.

[0148] Weigh 4.0 g (100 mmol) of NaOH into a 250 mL round-bottom flask, then add 120 mL of methanol. Stir until the solid dissolves. Weigh 17.0 g of Hibpm (100 mmol) and slowly add it to the NaOH solution using a constant pressure funnel. The solution changes from a colorless, transparent liquid to a pale yellow, transparent liquid. Stir for 5 h. Weigh 14.9 g of Zn(NO₃)₂·6H₂O (50 mmol) and dissolve it in 60 mL of methanol. Slowly add the solution. A white solid quickly forms and dissolves rapidly. Continue adding the solution dropwise to 30 mL, but the resulting white solid no longer dissolves, and the solution becomes increasingly turbid with the formation of a white precipitate. Upon completion of the addition, the solution becomes a milky white suspension. Stir for 8 h. Separate layers are allowed to separate, with the upper layer being a pale yellow clear liquid and the lower layer being a white precipitate. Filter the filtrate. 60 mL of H₂O was added to the filtrate, quickly producing a viscous substance in the lower layer of the clear liquid. 60 mL of n-hexane was added with stirring to dissolve the viscous substance. The system was separated into layers, and the upper n-hexane phase was collected. 20 g of anhydrous sodium sulfate was added and filtered to obtain a pale yellow n-hexane solution. This solution was concentrated to 10 mL and recrystallized at -30°C to obtain 18.2 g of colorless crystals, i.e., 3(Zn(ibpm)₂)·2H₂O. The yield of 3(Zn(ibpm)₂)·2H₂O was 91%, and the melting range was 57.8°C-59.1°C.

[0149] The H NMR spectrum of 3(Zn(ibpm)2)·2H2O is: 1 HNMR (400MHz, C2D6SO, ppm)5.36(s,1H,O=C-CH-C=O),2.28(m,1H,-CH-(CH3)2),1.06(s,9H,-C(CH3)3),0.99(d,6H,-CH-(CH3)2);

[0150] The NMR carbon spectrum is: 13 C-NMR (101MHz, CDCl3, 25℃, ppm) δ199.39(C=O), 91.27(O=C-CH-C=O), 49.57(-C(CH3)3), 40.87(-CH-(CH3)2), 28.58(-C(CH3)3), 20.74(-CH-(CH3)2).

[0151] 2. Preparation of complex Zn(ibpm)2

[0152] 80.0 g (64.3 mmol) of Zn(ibpm)22H2O crystals were added to Schlenk flask A. A separate Schlenk flask B was assembled using a U-shaped tube. 40 g of phosphorus pentoxide was added to Schlenk flask B. The crystal mixture in Schlenk flask A was evacuated and slowly heated. At around 85°C, the crystals melted, transforming into a white, turbid liquid. Heating continued to 120°C, and a white powdery solid began to slowly emerge from the flask walls. The mixture was incubated for 12 hours. During this incubation, the system remained a white, turbid liquid with no significant changes. A small amount of liquid appeared in the U-shaped tube around 4 hours, reaching a peak value after 10 hours. After 12 hours of incubation, the mixture was returned to room temperature, and 100 mL of anhydrous n-hexane was added. The mixture was allowed to stand for 12 hours. The upper layer was a yellow clear liquid, and the lower layer was a white precipitate. Filtering with a sand filter separated the white powdery solid and approximately 120 mL of a pale yellow clear liquid. The volatile solvent was removed by vacuum, yielding 40 mL of a pale yellow, viscous liquid. The light yellow viscous liquid was evacuated and subjected to vacuum distillation, and the fraction with steam temperature of 170°C in the oil bath at 190°C was collected to obtain 15 mL of light yellow transparent liquid (about 20 g), namely Zn(ibpm)2, with a yield of 27% for Zn(ibpm)2.

[0153] The H NMR spectrum of Zn(ibpm)2 Figure 4 )for: 1 HNMR (400MHz, C2D6SO, ppm)5.35(s,1H,O=C-CH-C=O),2.27(m,1H,-CH-(CH3)2),1.05(s,9H,-C(CH3)3),0.98(d,6H,-CH-(CH3)2);

[0154] Its Zn(ibpm)2 NMR carbon spectrum ( Figure 5 )for: 13 C-NMR (101MHz, CDCl3, 25℃, ppm) δ199.36(C=O), 91.26(O=C-CH-C=O), 49.57(-C(CH3)3), 40.50(-CH-(CH3)2), 28.59(-C(CH3)3), 20.75(-CH-(CH3)2).

[0155] The structural formula of the complex Zn(ibpm)2 is shown below:

[0156]

[0157] 3. Preparation method of zinc oxide film

[0158] The zinc oxide film is prepared by replacing the complex Zn(thd)2 with the complex Zn(ibpm)2, comprising the steps of:

[0159] (1) Si(100) substrate was placed in a reaction chamber; the complex Zn(ibpm)2 was heated to 140°C to vaporize it and form a vapor-phase zinc source; the vapor-phase zinc source was introduced into the reaction chamber in the presence of a carrier gas (high-purity nitrogen, flow rate of 150 sccm) in a pulsed form (pulse time of 3 s) and deposited at 200°C to obtain a substrate with deposited zinc source;

[0160] (2) After completing a pulse, high-purity nitrogen is used for purging, and the purging time is 2s;

[0161] (3) Vacuuming H2O to vaporize it and form a gaseous oxygen source precursor; the oxygen source precursor is introduced into the reaction chamber in a pulsed form (pulse time is 0.8 s) to undergo a self-limiting reaction with the zinc source deposited on the substrate at 200°C;

[0162] (4) After completing a pulse, high-purity nitrogen is used for purging, and the purging time is 10 seconds;

[0163] (5) Repeat steps (1) to (4) 500 times to obtain a zinc oxide thin film with a thickness of 7.41 nm.

[0164] Example 12: A method for preparing a zinc oxide film with low carbon content

[0165] On the basis of Example 11, the pulse time in step (1) of 3 was changed to 2s, and the remaining steps were consistent with Example 7 to prepare a zinc oxide thin film with a thickness of 6.56 nm.

[0166] Example 13: A method for preparing a zinc oxide film with low carbon content

[0167] On the basis of Example 11, the pulse time in step (3) of 3 was changed to 0.8 s, and the remaining steps were consistent with Example 7 to prepare a zinc oxide thin film with a thickness of 6.91 nm.

[0168] Example 14: A method for preparing a zinc oxide film with low carbon content

[0169] On the basis of Example 11, the pulse time in step (1) of 3 was changed to 4 s, and the remaining steps were consistent with Example 1 to prepare a zinc oxide thin film with a thickness of 7.39 nm.

[0170] Example 15: A method for preparing a zinc oxide film with low carbon content

[0171] On the basis of Example 11, the pulse time in step (3) of 3 was changed to 1.0 s, and the remaining steps were consistent with Example 1 to prepare a zinc oxide thin film with a thickness of 7.60 nm.

[0172] Example 16: Membrane performance testing

[0173] According to the methods of Examples 1, 6, and 11, the zinc oxide film was prepared by changing the number of repetitions in step (5) to 1000 times.

[0174] (1) Surface roughness

[0175] The zinc oxide film was tested by SEM and AFM to detect the average thickness and surface roughness of the film. The results were as follows: Figure 6 (complex Zn(thd)2), Figure 7 (complex Zn(tmod)2), Figure 8 (Zn(ibpm)2) and shown in Table 1.

[0176] Table 1 Film thickness and roughness

[0177] Average film thickness (nm) Roughness (nm) <![CDATA[Example 1 - Complex Zn(thd)2]]> 21.81 0.89 <![CDATA[Example 6 - Complex Zn(tmod)2]]> 24.02 0.72 <![CDATA[Example 11 - Complex Zn(ibpm)2]]> 14.94 0.91

[0178] (2) Thin film element content

[0179] Detection at 200℃ under Ar + The XPS full spectrum before and after etching for 60 seconds, the results are as follows Figure 9 (complex Zn(thd)2, Figure 10 (Comparative Example 2), Figure 11 (Comparative Example 3), Figure 12 (Zn(tmod)2, Figure 13 (Zn(ibpm)2), wherein the element contents are shown in Table 2.

[0180] Table 2 Elemental composition of thin films

[0181] Carbon Zinc Oxygen Zinc:Oxygen <![CDATA[Example 1 - Complex Zn(thd)2]]> 5.6％ 46.48％ 47.92％ 0.97 <![CDATA[Example 6 - Complex Zn(tmod)2]]> 3.4％ 47.8％ 48.8％ 0.98 <![CDATA[Example 7 - Complex Zn(ibpm)2]]> 6.5％ 45.5％ 48.0％ 0.94 <![CDATA[Comparative Example 2 - O3 Oxygen Source Precursor]]> 61.58％ 2.48％ 35.93％ - Comparative Example 3-MBO oxygen source precursor 6.8％ 15.4％ 77.8％ -

[0182] The above results show that the zinc oxide films prepared with the complexes Zn(thd)2, Zn(tmod)2, and Zn(ibpm)2 have high carbon content and a smooth surface, which overcomes the safety hazards of the precursors in the original thin film deposition process and the problem of high carbon content.

[0183] Although the present invention has been disclosed above in terms of preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A method for preparing a low-carbon zinc oxide film, characterized in that ,, zinc oxide thin films were prepared by thermal atomic layer deposition technology using β-diketone zinc as zinc source precursor and H2O as reducing precursor.

2. The method according to claim 1, characterized in that The structural formula of β-diketone zinc is shown in any one of Formula I, Formula II, and Formula III:

3. The method according to claim 1, characterized in that The growth temperature of zinc oxide film in thermal atomic layer deposition technology is 150-250℃.

4. The method according to claim 1, wherein The method for preparing a zinc oxide thin film using thermal atomic layer deposition technology comprises the following steps: (1) placing a Si(100) substrate in a reaction chamber, introducing a vapor-phase zinc source into the reaction chamber in a pulsed manner for deposition, and obtaining a substrate on which the zinc source is deposited; (2) Filling the system with inert gas for purging; (3) introducing a gaseous oxygen source precursor into the reaction chamber in a pulsed form to react with the zinc source deposited on the substrate; (4) Filling the system with inert gas for purging to complete an atomic layer deposition (ALD) growth cycle; (5) Repeat steps (1) to (4) to obtain a zinc oxide film.

5. The method according to claim 4, characterized in that In step (1), the duration of a single pulse of the gaseous zinc source introduced into the reaction chamber in pulse form is 1 to 4 seconds; the gaseous zinc source is introduced in pulse form in the presence of a carrier gas, and the flow rate of the carrier gas is 150 to 200 sccm; the carrier gas is one of high-purity nitrogen gases.

6. The zinc oxide thin film prepared by the method according to any one of claims 1 to 5.

7. Use of the zinc oxide thin film according to claim 6 in the field of integrated circuit preparation or nanomaterials.

8. A product, characterized in that The product contains the zinc oxide film according to claim 6; the product includes electronic devices, optoelectronic devices, transparent conductive films, varistors and piezoelectric devices, antibacterial and packaging materials, coatings and rubber additives.

9. A method for reducing the carbon content in a zinc oxide film, characterized in that ,, zinc oxide thin films were prepared by thermal atomic layer deposition technology using β-diketone zinc as zinc source precursor and H2O as reducing precursor.

10. The method according to claim 9, characterized in that The structural formula of β-diketone zinc is shown in any one of Formula I, Formula II, and Formula III:

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