A multilayer thin film and its preparation method

Abstract

This invention belongs to the field of thin film preparation technology and discloses a multilayer thin film and its preparation method. The multilayer thin film includes a titanium thin film and an indium cerium titanium tantalum oxide thin film deposited on the titanium thin film; the thickness of the titanium thin film accounts for 5-15% of the total thickness of the multilayer thin film. By controlling the thickness ratio of the titanium thin film in the multilayer thin film, this invention has found that the multilayer thin film within this thickness ratio range not only has a lower sheet resistance but also effectively improves the transmittance of the film, resulting in a thin film with low resistance, higher transmittance, and lower reflectivity.

Description

Technical Field

[0001] This invention relates to the field of thin film preparation technology, and specifically to a multilayer thin film and its preparation method. Background Technology

[0002] Transparent conductive films have high conductivity and high transmittance in the visible light region, and are therefore used as electrodes for solar cells, liquid crystal display elements, and various other photosensitive elements. Among the transparent conductive films known for their use, ITO films are widely used in industry.

[0003] Sputtering is a commonly used method for preparing these transparent conductive films. The properties (resistivity, transmittance) of films prepared by sputtering are highly dependent on the film formation rate and the type and content of the gas introduced during the film formation process. Therefore, it is difficult to stably prepare transparent conductive films with fixed film thickness and properties.

[0004] Indium cerium titanium tantalum oxide thin films are widely used due to their high mobility, but their amorphous silicon contact resistance is high, and how to reduce the impact of high resistance has become a technical challenge.

[0005] Prior art 1: Chinese patent 201010616147.5 discloses a method for preparing cobalt titanate thin films by dual-target magnetron sputtering. The method involves granulating and pre-calcining TiO2 and Co2O3 targets to prepare TiO2 and Co2O3 targets respectively, and then placing them into two RF target positions of a magnetron sputtering instrument. The substrate is then immersed in a mixture of acetone and ethanol and ultrasonically cleaned for later use. The treated substrate is placed on the deposition sample stage of the magnetron sputtering instrument, and a vacuum is drawn into the deposition chamber and sample chamber. The substrate heating temperature is set to 100℃-600℃, and Ar gas is introduced into the deposition chamber to perform backsputtering cleaning on the substrate surface. After backsputtering cleaning, RF sputtering power is applied to start the deposition process on the substrate. After deposition is completed, when the temperature in the deposition chamber drops to room temperature, the vacuum system and the main power supply are turned off, yielding the cobalt titanate thin film.

[0006] Existing technology 1 uses titanium and cobalt oxides to prepare two targets, respectively, and synthesizes CoTiO3 thin films in one step by radio frequency magnetron sputtering under substrate heating conditions. This technology provides a technical approach to reduce the resistance of indium cerium titanium tantalum oxide thin films. It can form thin films with the advantages of low resistance, high transmittance and low reflectance by sputtering two targets with different materials.

[0007] However, in actual experiments, it was found that the thin film formed by sputtering indium cerium titanium tantalum oxide target with other targets with low resistance properties, such as titanium target, will have large variations in resistance, transmittance and reflectance at various points on the film due to the uneven composition of the thin film.

[0008] Therefore, the technical problem to be solved by the present invention is: how to obtain a thin film with low resistance, high transmittance, and low reflectance. Summary of the Invention

[0009] One of the objectives of this invention is to provide a laminated thin film with a double-layer structure, wherein a titanium thin film is deposited before depositing an indium cerium titanium tantalum oxide thin film, which can effectively reduce the sheet resistance of the film and maintain the film's high transmittance and low reflectance.

[0010] Another objective of this invention is to provide a method for preparing a multilayer thin film, which can produce a thin film with low resistance, high transmittance, and low reflectance.

[0011] To achieve the above objectives, the present invention provides a laminated thin film comprising a titanium thin film and an indium cerium titanium tantalum oxide thin film deposited on the titanium thin film; wherein the thickness of the titanium thin film accounts for 5-15% of the total thickness of the laminated thin film.

[0012] This invention uses a titanium thin film with low resistance as a base film, and deposits an indium cerium titanium tantalum oxide thin film with high mobility on the base film to obtain a thin film with good density and uniformity, as well as low sheet resistance, high transmittance and low reflectance.

[0013] Theoretically, the higher the proportion of titanium thin film in the laminated film, the lower the sheet resistance of the laminated film will be, but the worse the transmittance of the laminated film will be. This is determined by the thin film characteristics of titanium thin film and indium cerium titanium tantalum oxide film respectively.

[0014] However, experiments have shown that in the laminated thin film of the present invention, the specific thickness ratio of the titanium thin film can simultaneously improve the electrical and optical properties of the laminated thin film. In the technical solution of the present invention, the thickness of the titanium thin film is within the range of 5-15% of the thickness of the film layer, which can enable the titanium thin film and the indium cerium titanium tantalum oxide thin film in the laminated thin film to have a synergistic effect, effectively improving the transmittance of the laminated thin film and reducing the sheet resistance and reflectivity of the laminated thin film.

[0015] Preferably, the thickness of the titanium thin film is 5-15 nm, and the thickness of the indium cerium titanium tantalum oxide thin film is 85-95 nm.

[0016] The laminated thin film also includes a substrate on which the titanium thin film is deposited, and further, the substrate is an alkali-free ultrathin glass.

[0017] Furthermore, the substrate has an alkali content ≤0.05wt% and a room temperature thermal expansion coefficient ≤35.5×10⁻⁶. -7 / K, glass with a thickness of 0.2-1.1mm.

[0018] Preferably, the titanium thin film is formed by DC magnetron sputtering of a titanium target, wherein the titanium target has a purity ≥ 99.99% and a density ≥ 4.5 g / cm³. 3 .

[0019] Using this material for titanium sputtering targets can maximize the advantage of the low resistance of titanium thin films.

[0020] Preferably, the indium cerium titanium tantalum oxide thin film is formed by DC magnetron sputtering of an indium cerium titanium tantalum oxide target, wherein the indium cerium titanium tantalum oxide target has a purity ≥99.9% and a density ≥7.06 g / cm³. 3 .

[0021] Using this material, the high mobility of the indium cerium titanium tantalum oxide target can be maximized.

[0022] Furthermore, in the indium cerium titanium tantalum oxide target material, based on the total mass of titanium oxide, tantalum oxide, cerium oxide and indium oxide as 100%, titanium oxide accounts for 0.12%-10% of the total mass, tantalum oxide accounts for 0.48%-27.66% of the total mass, cerium oxide accounts for 0.38%-21.55% of the total mass, and indium oxide accounts for 40.79%-99.02% of the total mass.

[0023] This invention also discloses a method for preparing a multilayer thin film, comprising the following steps:

[0024] Step 1: Clean the substrate;

[0025] Step 2: Deposit a titanium thin film on the substrate;

[0026] Step 3: Deposit an indium cerium titanium tantalum oxide thin film onto a titanium thin film.

[0027] Steps 2 and 3 in the above method for preparing multilayer thin films are both performed in a magnetron sputtering apparatus. Since the DC magnetron sputtering growth process of the magnetron sputtering apparatus is an existing technology in this field, those skilled in the art can perform thin film sputtering growth and deposition according to the existing process.

[0028] Furthermore, the specific operation of step 1 is as follows: the substrate is ultrasonically cleaned in sequence using acetone, anhydrous ethanol and water as cleaning solutions, and then the substrate is dried with nitrogen gas.

[0029] Furthermore, step 2 specifically involves depositing a titanium thin film onto a substrate using a titanium target via DC magnetron sputtering, wherein the distance between the titanium target and the center of the substrate is 6-13 cm, and the sputtering power density is 2.5-5.5 W / cm². 2 The sputtering pressure is 0.2-0.8 Pa, and the growth temperature is 20-27℃.

[0030] Furthermore, step 3 specifically involves: depositing an indium cerium titanium tantalum oxide thin film onto a titanium thin film using a DC magnetron sputtering target, wherein the distance between the indium cerium titanium tantalum oxide target and the center of the substrate is 6-13 cm, and the sputtering power density is 2.5-5.5 W / cm². 2 The sputtering pressure is 0.2-0.8 Pa, and the growth temperature is 20-27℃.

[0031] Beneficial effects

[0032] Compared with the prior art, the present invention has at least the following advantages:

[0033] (1) The present invention deposits a titanium film before depositing an indium cerium titanium tantalum oxide film, which can prepare a film with low sheet resistance, high transmittance and low reflectance.

[0034] (2) By controlling the thickness ratio of the titanium film in the laminated film, the present invention found that the laminated film within the thickness ratio range not only has a lower sheet resistance, but also effectively improves the transmittance of the film, thus obtaining a film with low resistance, higher transmittance and lower reflectance.

[0035] (3) The present invention discloses a method for preparing a multilayer thin film, which can obtain a thin film with low resistance, high transmittance and low reflectance. Detailed Implementation

[0036] The present invention will be further described below with reference to embodiments, but this does not constitute any limitation on the present invention. Any limited modifications made within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0037] To illustrate the technical content of the present invention in detail, the following description is provided in conjunction with the embodiments.

[0038] In the following examples and comparative examples, the titanium target material has a purity of 99.99% and a density of 4.5 g / cm³. 3 The indium cerium titanium tantalum oxide target has a purity of 99.9% and a density of 7.06 g / cm³. 3 In the indium cerium titanium tantalum oxide target material, based on the total mass of titanium oxide, tantalum oxide, cerium oxide and indium oxide as 100%, titanium oxide accounts for 1.2% of the total mass, tantalum oxide accounts for 0.8% of the total mass, cerium oxide accounts for 0.7% of the total mass, and indium oxide accounts for 97.3% of the total mass.

[0039] In Examples 1-3 and Comparative Examples 1-2 below, the laminated films were prepared by the following steps:

[0040] Step 1: The substrate was ultrasonically cleaned sequentially using acetone, anhydrous ethanol, and water as cleaning solutions, and then dried with nitrogen gas. The substrate had an alkali content of 0.04 wt% and a coefficient of thermal expansion of 35.5 × 10⁻⁶ at room temperature. -7 / K, glass with a thickness of 1mm;

[0041] Step 2: The titanium target is mounted on the cathode target position 1 of the magnetron sputtering instrument, and a titanium thin film is deposited on the substrate by DC magnetron sputtering. The distance between the titanium target and the center of the substrate is 7 cm, and the sputtering power density is 2.6 W / cm². 2 The sputtering pressure was 0.6 Pa, and the growth temperature was 25 °C.

[0042] Step 3: The indium cerium titanium tantalum oxide target is mounted on the cathode target 2 of the magnetron sputtering instrument. A thin film of indium cerium titanium tantalum oxide is deposited on the titanium film by DC magnetron sputtering. The distance between the indium cerium titanium tantalum oxide target and the center of the substrate is 7 cm, and the sputtering power density is 2.6 W / cm². 2 The sputtering pressure was 0.6 Pa, and the growth temperature was 25 °C.

[0043] It should be noted that the thickness of the laminated film of the present invention can be prepared as needed, rather than being fixed at 100 nm. In the laminated film of the present invention, the thickness of the titanium film accounts for 5-15% of the total thickness of the laminated film, and the indium cerium titanium tantalum oxide film accounts for 85-95% of the total thickness of the laminated film.

[0044] Example 1

[0045] A multilayer thin film includes a titanium thin film deposited on a substrate and an indium cerium titanium tantalum oxide thin film deposited on the titanium thin film, wherein the titanium thin film has a thickness of 5 nm and the indium cerium titanium tantalum oxide thin film has a thickness of 95 nm.

[0046] Example 2

[0047] A multilayer thin film includes a titanium thin film deposited on a substrate and an indium cerium titanium tantalum oxide thin film deposited on the titanium thin film, wherein the titanium thin film has a thickness of 10 nm and the indium cerium titanium tantalum oxide thin film has a thickness of 90 nm.

[0048] Example 3

[0049] A multilayer thin film includes a titanium thin film deposited on a substrate and an indium cerium titanium tantalum oxide thin film deposited on the titanium thin film, wherein the titanium thin film has a thickness of 15 nm and the indium cerium titanium tantalum oxide thin film has a thickness of 85 nm.

[0050] Comparative Example 1

[0051] A multilayer thin film includes a titanium thin film deposited on a substrate and an indium cerium titanium tantalum oxide thin film deposited on the titanium thin film, wherein the titanium thin film has a thickness of 20 nm and the indium cerium titanium tantalum oxide thin film has a thickness of 80 nm.

[0052] Comparative Example 2

[0053] A multilayer thin film includes a substrate, a titanium thin film deposited on the substrate, and an indium cerium titanium tantalum oxide thin film deposited on the titanium thin film, wherein the titanium thin film has a thickness of 2 nm and the indium cerium titanium tantalum oxide thin film has a thickness of 97 nm.

[0054] Comparative Example 3

[0055] An indium cerium titanium tantalum oxide thin film is prepared by the following steps: Step 1: The substrate is ultrasonically cleaned sequentially using acetone, anhydrous ethanol, and water as cleaning solutions, and then dried with nitrogen gas. The substrate has an alkali content of 0.04 wt% and a room temperature thermal expansion coefficient of 35.5 × 10⁻⁶. -7 / K, glass with a thickness of 1mm;

[0056] Step 2: The indium cerium titanium tantalum oxide target is mounted on the cathode target 2 of the magnetron sputtering instrument. A thin film of indium cerium titanium tantalum oxide is deposited on the substrate by DC magnetron sputtering. The distance between the indium cerium titanium tantalum oxide target and the center of the substrate is 7 cm, and the sputtering power density is 2.6 W / cm². 2 The sputtering pressure was 0.6 Pa, and the growth temperature was 25 °C.

[0057] The thickness of the indium cerium titanium tantalum oxide thin film is 100 nm.

[0058] Comparative Example 4

[0059] An indium cerium titanium tantalum oxide thin film is prepared by the following steps: Step 1: The substrate is ultrasonically cleaned sequentially using acetone, anhydrous ethanol, and water as cleaning solutions, and then dried with nitrogen gas. The substrate has an alkali content of 0.04 wt% and a room temperature thermal expansion coefficient of 35.5 × 10⁻⁶. -7 / K, glass with a thickness of 1mm;

[0060] Step 2: The titanium target is mounted on the cathode target position 1 of the magnetron sputtering instrument, and a titanium thin film is deposited on the substrate by DC magnetron sputtering. The distance between the titanium target and the center of the substrate is 7 cm, and the sputtering power density is 2.6 W / cm². 2 The sputtering pressure was 0.6 Pa, and the growth temperature was 25 °C.

[0061] The thickness of the titanium film is 100 nm.

[0062] Performance testing

[0063] Test method:

[0064] Sheet resistance: Four-probe sheet resistance tester

[0065] Transmittance: UV-Vis UV-Vis spectrophotometer

[0066] Reflectance: UV-Vis UV-Vis spectrophotometer

[0067] The films prepared in Examples 1-3 and Comparative Examples 1-4 were tested according to the above test methods, and the results are shown in Table 1.

[0068] Table 1. Results of electrical and optical properties of the thin films prepared in Examples 1-3 and Comparative Examples 1-4

[0069] Shear resistance / Ω Transmittance / % Reflectivity / % Example 1 171 88.2155 9.6835 Example 2 162 87.9192 10.8235 Example 3 153 87.2937 11.6053 Comparative Example 1 144 82.8900 15.9379 Comparative Example 2 228 84.7438 14.1552 Comparative Example 3 233 86.8901 12.0089 Comparative Example 4 109 62.7545 36.0789

[0070] According to the results in Table 1:

[0071] According to the data from Examples 1-3 and Comparative Examples 1-4, by controlling the thickness ratio of the titanium film in the laminated film, the laminated film produced by the present invention not only has a lower sheet resistance, but also effectively improves the transmittance of the film, resulting in a film with low resistance, higher transmittance, and lower reflectance.

[0072] A comparison of the data from Examples 1-3 and Comparative Examples 1-3 shows that controlling the thickness ratio of the titanium film in the laminated film of the present invention to be in the range of 5-15% can significantly improve the transmittance of the film, which is higher than that of the indium cerium titanium tantalum oxide film produced in Comparative Example 3. According to Comparative Examples 1 and 2, it can be seen that the presence of the titanium film in the laminated film with the same thickness will reduce the transmittance of the film. However, the present invention effectively improves the transmittance of the film by controlling the thickness ratio of the titanium film in the laminated film. Although the increase in transmittance is not very large, it produces unexpected technical effects.

[0073] According to the data comparison of Examples 1-3 and Comparative Examples 1-4, the sheet resistance of the thin film decreases as the thickness of the titanium thin film increases.

[0074] The embodiments presented herein are merely selected implementations based on combinations of all possible embodiments. The appended claims should not be limited to the embodiments described herein. Some numerical ranges used in the claims include sub-ranges within them, and variations within these ranges should also be covered by the appended claims.

Claims

1. A laminated thin film, characterized in that, It includes a titanium thin film and an indium cerium titanium tantalum oxide thin film deposited on the titanium thin film; the thickness of the titanium thin film accounts for 5-15% of the total thickness of the stacked films; the thickness of the titanium thin film is 5-15 nm, and the thickness of the indium cerium titanium tantalum oxide thin film is 85-95 nm.

2. The laminated film according to claim 1, characterized in that, It also includes a substrate, on which the titanium thin film is deposited, wherein the substrate has an alkali content of ≤0.05wt% and a room temperature thermal expansion coefficient of ≤35.5×10⁻⁶. -7 / K, glass with a thickness of 0.2-1.1mm.

3. The laminated film according to claim 1, characterized in that, The titanium thin film is formed by DC magnetron sputtering of a titanium target, wherein the titanium target has a purity of ≥99.99% and a density of ≥4.5 g / cm³. 3 .

4. The laminated film according to claim 1, characterized in that, The indium cerium titanium tantalum oxide thin film is formed by DC magnetron sputtering of an indium cerium titanium tantalum oxide target. The indium cerium titanium tantalum oxide target has a purity of ≥99.9% and a density of ≥7.06 g / cm³. 3 .

5. The laminated film according to claim 4, characterized in that, The indium cerium titanium tantalum oxide target material comprises, based on the total mass of titanium oxide, tantalum oxide, cerium oxide and indium oxide as 100%, titanium oxide accounts for 0.12%-10% of the total mass, tantalum oxide accounts for 0.48%-27.66% of the total mass, cerium oxide accounts for 0.38%-21.55% of the total mass, and indium oxide accounts for 40.79%-99.02% of the total mass.

6. A method for preparing a multilayer thin film as described in any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Clean the substrate; Step 2: Deposit a titanium thin film on the substrate; Step 3: Deposit an indium cerium titanium tantalum oxide thin film onto a titanium thin film.

7. The method for preparing a multilayer thin film according to claim 6, characterized in that, The specific operation of step 1 is as follows: the substrate is ultrasonically cleaned in sequence using acetone, anhydrous ethanol and water as cleaning solutions, and then the substrate is dried with nitrogen gas.

8. The method for preparing a multilayer thin film according to claim 6, characterized in that, The specific operation of step 2 is as follows: a titanium thin film is deposited on a substrate by DC magnetron sputtering of a titanium target, wherein the distance between the titanium target and the center of the substrate is 6-13 cm, and the sputtering power density is 2.5-5.5 W / cm². 2 The sputtering pressure is 0.2-0.8 Pa, and the growth temperature is 20-27℃.

9. The method for preparing a multilayer thin film according to claim 6, characterized in that, The specific operation of step 3 is as follows: An indium cerium titanium tantalum oxide thin film is deposited on a titanium thin film by DC magnetron sputtering of an indium cerium titanium tantalum oxide target. The distance between the indium cerium titanium tantalum oxide target and the center of the substrate is 6-13 cm, and the sputtering power density is 2.5-5.5 W / cm². 2 The sputtering pressure is 0.2-0.8 Pa, and the growth temperature is 20-27℃.