Silver alloy composite film and method for manufacturing the same

Abstract

The application provides a silver alloy composite film and a preparation method thereof, and belongs to the technical field of OLEDs. The silver alloy composite film is prepared by alternately depositing CrMoNbTaW film layers and Ag film layers on a substrate by double-target sputtering of a magnetron sputtering coater. The composite film has the CrMoNbTaW film layer as the top layer, and the CrMoNbTaW film layer is one layer more than the Ag film layer. The silver alloy composite film prepared by the application has stable performance and composition, high conductivity and high reflectivity, the preparation process is simple, and the silver alloy composite film is suitable for the fields of reflective electrode films, liquid crystal displays, optical recording media, organic light emitting diodes and the like, can resist electromigration, and can improve the anti-sulfuration corrosion resistance and service life.

Description

Technical Field

[0001] This invention relates to the field of OLED technology, and specifically to a silver alloy composite film and its preparation method. Background Technology

[0002] Thin films formed by pure silver sputtering targets have excellent properties such as high reflectivity, low extinction coefficient, high thermal conductivity, low resistivity, and good surface smoothness, making them suitable for reflective electrode films, liquid crystal displays, optical recording media, organic light-emitting diodes, and electrochromic applications.

[0003] However, pure silver has disadvantages such as easy oxidation, poor resistance to sulfidation and poor resistance to chlorine corrosion. Chlorine corrosion and sulfide corrosion will reduce the reflectivity and conductivity of silver films and make the adhesion between the film and the substrate worse, which will seriously affect its performance.

[0004] JP-A-63-187399, JPA-7-114841, and TW92128677A disclose a three-layer transparent electrode with a silver layer sandwiched between two ITO layers. This electrode exhibits low resistivity and improved transparency, making it suitable for use in liquid crystal displays. However, these inventions are not particularly useful due to the relatively low corrosion resistance of pure silver.

[0005] Therefore, it is necessary to provide a novel silver alloy composite film that can improve the sulfidation resistance and corrosion resistance of silver films. High-entropy alloys are a class of alloys made by mixing and melting five or more, but no more than 13, main elements in equimolar or near-equimolar ratios. Vacuum-deposited high-entropy alloy films exhibit good thermal stability and surface smoothness. A sandwich structure composed of alternating high-entropy alloy and Ag films can effectively prevent the diffusion of impurities such as O and S into the Ag film, thus enabling better applications in liquid crystal displays, organic light-emitting diodes, and electrochromic fields. Summary of the Invention

[0006] The present invention aims to overcome the deficiencies in the prior art and provide a silver alloy composite film that still has high reflectivity after being subjected to high temperature and humidity, and a method for preparing the same.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A silver alloy composite thin film is prepared by alternating deposition of CrMoNbTaW film (represented by A) and Ag film (represented by B) on a substrate using a magnetron sputtering coating instrument. The composite thin film has the CrMoNbTaW film as the top layer and is a multilayer composite thin film with an A / B / A…A / B / A structure (i.e., the CrMoNbTaW film has one more layer than the Ag film).

[0009] Furthermore, the thickness of a single Ag film is 10–90 nm, and the thickness of a single CrMoNbTaW film is 2–30 nm.

[0010] Preferably, the thickness of a single CrMoNbTaW film is 5 nm.

[0011] Preferably, the number of deposited Ag and CrMoNbTaW films is controlled according to the thickness of a single Ag film and a single CrMoNbTaW film, so that the total thickness of the A / B / A…A / B / A type silver alloy composite film is 100~120nm.

[0012] The above-mentioned silver alloy composite film is prepared by using magnetron sputtering dual-target alternating deposition technology. The cleaned and dried substrate is placed in the vacuum chamber of the coating equipment. After evacuation to the set value, argon gas is introduced. A negative bias voltage is applied to the substrate, and ion cleaning is performed using a magnetron sputtering DC Ag target and a magnetron sputtering DC CrMoNbTaW high-entropy alloy target. Then, the magnetron sputtering DC Ag target current, the CrMoNbTaW high-entropy alloy target current, and the substrate bias voltage are changed to alternately deposit CrMoNbTaW film and Ag-based alloy film on the substrate surface. During the deposition process, the deposition time, argon gas flow rate, and target current are controlled to obtain a silver alloy composite film deposited on the substrate. The specific steps are as follows:

[0013] The cleaned and dried substrate is clamped on a workpiece holder and sent into the vacuum chamber of a magnetron sputtering coating instrument. The vacuum chamber of the magnetron sputtering coating instrument is constructed to include at least one CrMoNbTaW high-entropy alloy target site and at least one Ag target site, as well as at least one sample stage. Then, CrMoNbTaW film and Ag film are deposited independently and sequentially according to the following steps:

[0014] (1) Mount the CrMoNbTaW high-entropy alloy target and the Ag target on the target positions respectively, and mount the substrate on the sample stage;

[0015] (2) CrMoNbTaW film (represented by A) and Ag film (represented by B) are deposited alternately on the substrate, and the thickness of a single CrMoNbTaW film is controlled to be 2~30 nm and the thickness of a single Ag film is controlled to be 10~90 nm.

[0016] (3) Using A as the top layer, a multilayer composite film with an A / B / A…A / B / A structure was prepared.

[0017] This invention employs magnetron sputtering dual-target alternating deposition technology to deposit a uniform silver alloy composite film on a substrate. The film consists of an Ag film layer with a thickness of 10-90 nm and a CrMoNbTaW high-entropy alloy film layer with a thickness of 2-30 nm (preferably 5 nm). The number of A and B layers deposited is controlled according to the thickness of each individual Ag layer, resulting in a total thickness of 100-120 nm for the A / B / A…A / B / A type multilayer film. Even after high-temperature and high-humidity testing, the film retains high reflectivity and exhibits good adhesion and corrosion resistance.

[0018] The beneficial effects of this invention are:

[0019] 1) All elements in the CrMoNbTaW alloy have a body-centered cubic crystal structure; the CrMoNbTaW alloy forms a thermodynamically stable amorphous homogeneous solid solution; a 5nm thick CrMoNbTaW film can form a continuous covering film on the Ag film, inhibiting the contact and grain growth of adjacent Ag films, and significantly inhibiting the diffusion of impurities such as O and S from the surface to the Ag film.

[0020] 2) None of the elements in the CrMoNbTaW alloy are miscible with Ag. The Ag film deposited on the CrMoNbTaW film exhibits a (111) preferred orientation, has a smooth surface, and has good resistance to electromigration.

[0021] 3) Compared with the "ITO / Ag / ITO" film, the multilayer composite film formed by the alternating deposition of the "high-entropy alloy film / silver film" in this invention has a higher reflectivity in the blue light band, which can improve color resolution and can be better applied to liquid crystal displays, etc.

[0022] The silver alloy composite film prepared under the above conditions has high reflectivity and corrosion resistance at high temperatures, and is suitable for fields such as reflective electrode films, liquid crystal displays, optical recording media, and organic light-emitting diodes, which can improve their anti-sulfurization, corrosion resistance and service life. Attached Figure Description

[0023] Figure 1 The images show the XRD patterns of the silver alloy composite films prepared in Examples 1, 3, and 1.

[0024] Figure 2 The reflectance diagrams are for the silver alloy composite films prepared in Examples 1-3 and Comparative Examples 1-2.

[0025] Figure 3 This is a SEM image of the silver alloy composite film prepared in Example 3.

[0026] Figure 4The image shows a SEM image of the silver alloy composite film prepared in Example 3 after a reliability test.

[0027] Figure 5 The image shows a SEM image of the silver alloy composite film prepared in Comparative Example 1.

[0028] Figure 6 The image shows the SEM image of the silver alloy composite film prepared in Comparative Example 1 after a reliability test. Detailed Implementation

[0029] A silver alloy composite film was deposited on a substrate using a magnetron sputtering deposition system. The vacuum chamber of the magnetron sputtering deposition system was constructed to include at least one CrMoNbTaW high-entropy alloy target site and at least one Ag target site, as well as at least one sample stage. The substrate was placed on the sample stage, and CrMoNbTaW and Ag films were deposited sequentially and independently. The specific steps for preparing the silver alloy composite film are as follows:

[0030] (1) Mount the CrMoNbTaW high-entropy alloy target and the Ag target on the target positions respectively, and install the clean substrate on the sample stage;

[0031] (2) CrMoNbTaW film (represented by A) and Ag film (represented by B) are deposited alternately on the substrate, and the thickness of a single CrMoNbTaW film is controlled to be 2~30 nm and the thickness of a single Ag film is controlled to be 10~90 nm.

[0032] (3) Using A as the top layer, a multilayer composite film with an A / B / A…A / B / A structure is prepared, which includes at least one Ag film layer and one CrMoNbTaW film layer that is one more than the Ag film layer.

[0033] Preferably, the thickness of a single CrMoNbTaW film is 5 nanometers.

[0034] Preferably, the number of deposited A and B layers is controlled according to the thickness of a single Ag film layer and a single CrMoNbTaW film layer, so that the total thickness of the multilayer composite film of the A / B / A…A / B / A type structure is 100~120 nanometers.

[0035] Example 1

[0036] A silver alloy composite film was deposited on a substrate using a magnetron sputtering deposition system. The vacuum chamber of the magnetron sputtering deposition system was constructed to include at least one CrMoNbTaW alloy target site and at least one Ag target site, as well as at least one sample stage. The substrate was placed on the sample stage, allowing for the sequential and independent deposition of CrMoNbTaW and Ag film layers. The steps for preparing the silver alloy composite film are as follows:

[0037] (1) Mount the CrMoNbTaW high-entropy alloy target and the Ag target on the target positions respectively, and install the clean substrate on the sample stage;

[0038] (2) CrMoNbTaW film (represented by A) and Ag film (represented by B) are deposited alternately on the substrate, with the thickness of a single CrMoNbTaW film controlled to be 5 nm and the thickness of a single Ag film controlled to be 20 nm.

[0039] (3) Using A as the top layer, a multilayer composite film with the structure A / B / A / B / A / B / A / B / A was prepared, which includes 4 Ag film layers and 5 CrMoNbTaW film layers.

[0040] Example 2

[0041] A silver alloy composite film was deposited on a substrate using a magnetron sputtering deposition system. The vacuum chamber of the magnetron sputtering deposition system was constructed to include at least one CrMoNbTaW alloy target site and at least one Ag target site, as well as at least one sample stage. The substrate was placed on the sample stage, allowing for the sequential and independent deposition of CrMoNbTaW and Ag film layers. The steps for preparing the silver alloy composite film are as follows:

[0042] (1) Mount the CrMoNbTaW high-entropy alloy target and the Ag target on the target positions respectively, and install the clean substrate on the sample stage;

[0043] (2) CrMoNbTaW film (represented by A) and Ag film (represented by B) are deposited alternately on the substrate, with the thickness of a single CrMoNbTaW film controlled to be 5 nm and the thickness of a single Ag film controlled to be 50 nm.

[0044] (3) Using A as the top layer, a multilayer thin film with an A / B / A / B / A structure was prepared, which includes two Ag film layers and three CrMoNbTaW film layers.

[0045] Example 3

[0046] A silver alloy multilayer thin film was deposited on a substrate using a magnetron sputtering deposition system. The vacuum chamber of the magnetron sputtering deposition system was constructed to include at least one CrMoNbTaW alloy target site and at least one Ag target site, as well as at least one sample stage. The substrate was placed on the sample stage, allowing for the sequential and independent deposition of CrMoNbTaW and Ag films. The steps for preparing the silver alloy multilayer thin film are as follows:

[0047] (1) Mount the CrMoNbTaW high-entropy alloy target and the Ag target on the target positions respectively, and install the clean substrate on the sample stage;

[0048] (2) CrMoNbTaW film (represented by A) and Ag film (represented by B) are deposited alternately on the substrate, with the thickness of a single CrMoNbTaW film controlled to be 5 nm and the thickness of a single Ag film controlled to be 90 nm.

[0049] (3) Using A as the top layer, a multilayer film with an A / B / A structure was prepared, which includes one Ag film layer and two CrMoNbTaW film layers.

[0050] Comparative Example 1

[0051] A silver alloy multilayer thin film was deposited on a substrate using a magnetron sputtering deposition system. The vacuum chamber of the magnetron sputtering deposition system was constructed to include at least one ITO target site and at least one Ag alloy target site, as well as at least one sample stage. The substrate was placed on the sample stage, allowing for the sequential and independent deposition of ITO and Ag alloy films. The steps for preparing the silver alloy multilayer thin film are as follows:

[0052] (1) Mount the ITO target and Ag alloy target on the target positions respectively, and install the clean substrate on the sample stage;

[0053] (2) ITO film (represented by C) and Ag alloy film (represented by D) are deposited alternately on the substrate, with the thickness of a single ITO film controlled to be 10 nanometers and the thickness of a single Ag alloy film controlled to be 90 nanometers.

[0054] (3) Using C as the top layer, a multilayer thin film with a “C / D / C” structure was prepared, which contains one Ag film layer and two ITO film layers.

[0055] Comparative Example 2

[0056] A comparative silver alloy multilayer film was deposited on a substrate using a magnetron sputtering deposition system. The vacuum chamber of the magnetron sputtering deposition system was constructed to include at least one ITO target site and at least one Ag alloy target site, as well as at least one sample stage. The substrate was placed on the sample stage, allowing for the sequential and independent deposition of ITO and Ag alloy films. The steps for preparing the silver alloy multilayer film are as follows:

[0057] (1) Mount the ITO target and Ag alloy target on the target positions respectively, and install the clean substrate on the sample stage;

[0058] (2) ITO film (represented by C) and Ag alloy film (represented by D) are deposited alternately on the substrate, with the thickness of a single ITO film being controlled to be 5 nanometers and the thickness of a single Ag alloy film being controlled to be 20 nanometers.

[0059] (3) Using C as the top layer, a multilayer thin film with a structure of “C / D / C / D / C / D / C / D / C” was prepared, which includes 4 Ag alloy film layers and 5 ITO film layers.

[0060] The silver alloy composite films prepared in Examples 1-3 and Comparative Examples 1-2 were left to stand for 7 days at 85°C and 85% humidity for reliability testing. The sheet resistance of the silver alloy composite films before and after the reliability test was measured using a four-probe tester, and the results are listed in Table 1.

[0061] Table 1

[0062]

[0063] As can be seen from the data in Table 1, the back resistance of the silver alloy composite film provided by the present invention does not change much after the reliability test, indicating that the microstructure of the silver alloy composite film provided by the present invention does not change much after the reliability test, and its anti-electromigration ability and stability are excellent.

[0064] Figure 1 The images show the XRD patterns of the silver alloy composite films prepared in Examples 1, 3, and Comparative Example 1. Figure 1 It can be seen that, compared with Comparative Example 1, the I of Ag in Examples 1 and 3 is... （111） / I （200） The higher value of the (111) and (200) crystal plane diffraction intensity ratio indicates that the composite film with the "high entropy alloy film / silver film" stack structure exhibits a stronger (111) preferred orientation.

[0065] Figure 2 The figures show the reflectance of the silver alloy composite films prepared in Examples 1-3 and Comparative Examples 1-2. As can be seen from the figures, in the visible light range, the multilayer composite films formed by alternating deposition of the "high-entropy alloy film / silver film" stack structure provided by this invention have higher reflectance than the "ITO / Ag / ITO" film, especially in the blue light band. This improves color resolution and makes them better suited for applications such as liquid crystal displays.

[0066] Figure 3 , Figure 5 SEM images of the silver alloy composite films prepared in Example 3 and Comparative Example 1, respectively. Figure 4 , Figure 6 The images show SEM images of the silver alloy composite films prepared in Example 3 and Comparative Example 1 after reliability testing. Figures 3-6 It can be seen that the silver alloy composite film prepared in Comparative Example 1 formed large pores after being exposed to high temperature and high humidity. The high entropy alloy film layer in the silver alloy composite film provided by the present invention has high corrosion resistance and anti-electron migration ability, and formed extremely small pores after being exposed to high temperature and high humidity.

Claims

1. A silver alloy composite thin film, characterized in that: It is made by alternating deposition of CrMoNbTaW and Ag films on a substrate using a magnetron sputtering coating instrument. The composite film has the CrMoNbTaW film as the top layer, and the CrMoNbTaW film has one more layer than the Ag film.

2. The silver alloy composite film according to claim 1, characterized in that: The thickness of a single Ag film is 10~90 nm, and the thickness of a single CrMoNbTaW film is 2~30 nm.

3. A silver alloy composite film according to claim 2, characterized in that: The thickness of a single CrMoNbTaW film is 5 nm.

4. The silver alloy composite film according to claim 1, characterized in that: The total thickness of the silver alloy composite film is 100~120nm.

5. The method for preparing the silver alloy composite thin film according to any one of claims 1 to 4, characterized in that: The cleaned and dried substrate is clamped on a workpiece holder and fed into the vacuum chamber of a magnetron sputtering coating instrument. The vacuum chamber of the magnetron sputtering coating instrument is constructed to include at least one CrMoNbTaW target site and at least one Ag target site, as well as at least one sample stage. CrMoNbTaW film and Ag film are deposited independently and sequentially according to the following steps: (1) Mount the CrMoNbTaW target and the Ag target on the target positions respectively, and mount the substrate on the sample stage; (2) CrMoNbTaW film and Ag film are deposited alternately on the substrate to obtain a silver alloy composite film with CrMoNbTaW film as the top layer.

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