A reinforced ruthenium-plated molybdenum sheet and its preparation method

Abstract

The present invention discloses an enhanced ruthenium-plated molybdenum sheet and a preparation method thereof, belonging to the technical field of ruthenium-plated molybdenum sheets. The preparation method comprises: vacuum sputtering a high-purity molybdenum coating with a thickness of 0.1 to 0.5 μm on the surface of a molybdenum sheet by magnetron sputtering to obtain a molybdenum-plated molybdenum sheet; oxidatively pickling and ion cleaning the molybdenum-plated molybdenum sheet, and then depositing a ruthenium coating with a thickness of 0.5 to 1 μm on the surface of the cleaned molybdenum-plated molybdenum sheet by vapor deposition to obtain the enhanced ruthenium-plated molybdenum sheet. The preparation method of the present invention has low requirements for the molybdenum sheet substrate, and can directly use unpolished rolled molybdenum sheets. A firmly adhered and tightly bonded ruthenium coating is formed on the substrate to obtain the enhanced ruthenium-plated molybdenum sheet.

Description

Technical Field

[0001] The present invention relates to the technical field of molybdenum sheets, in particular to the technical field of ruthenium-plated molybdenum sheets. Background Art

[0002] Molybdenum sheets are widely used in the packaging and heat dissipation of power semiconductor devices due to their excellent electrical and thermal conductivity. However, pure molybdenum sheets have poor corrosion resistance and are susceptible to oxidation at high temperatures, which affects their reliability in long-term use. Ruthenium, on the other hand, exhibits excellent corrosion and oxidation resistance in high-temperature environments and has good electrical conductivity, making it an ideal coating material for electronic components and electrical contacts. Ruthenium plating on molybdenum sheets can significantly improve their corrosion resistance, oxidation resistance, and electrical conductivity.

[0003] Traditional ruthenium plating processes for molybdenum sheets include multi-layer electroless ruthenium plating or electroplating followed by diffusion of ruthenium. These processes suffer from insufficient bonding strength and uneven coatings, leading to peeling and poor durability. Furthermore, both electroless and electroplating processes are complex, inefficient, and pose significant environmental risks. Physical vapor deposition (PVD) offers several advantages over electroless and electroplating methods, including lower process temperatures, shorter processing times, minimal sheet deformation, high efficiency, and a clean environment.

[0004] However, it is difficult to form an effective and reliable bond between the molybdenum substrate and the ruthenium coating by directly using PVD ruthenium plating, thereby obtaining a ruthenium-plated molybdenum sheet with high peel strength. Summary of the Invention

[0005] In view of the defects of the prior art, the object of the present invention is to provide an enhanced ruthenium-plated molybdenum sheet and a preparation method thereof.

[0006] The technical solutions of the present invention are as follows:

[0007] A method for preparing a reinforced ruthenium-plated molybdenum sheet, comprising:

[0008] (1) Using high-purity molybdenum as a target material, a high-purity molybdenum coating with a thickness of 0.1 to 0.5 μm is vacuum sputtered on the surface of the molybdenum sheet by magnetron sputtering to obtain a molybdenum-coated molybdenum sheet;

[0009] (2) oxidizing and pickling the molybdenum-plated sheet to obtain a pickled molybdenum-plated sheet;

[0010] (3) performing ion cleaning and activation on the molybdenum-plated molybdenum sheet after pickling by using an improved anode layer ion source to obtain an activated molybdenum-plated molybdenum sheet, wherein the improved anode layer ion source is obtained by replacing the inner cathode and outer cathode materials of the ordinary anode layer ion source with high-purity molybdenum;

[0011] (4) Depositing a ruthenium coating layer with a thickness of 0.5 to 1 μm on the surface of the activated molybdenum-plated molybdenum sheet by vapor deposition to obtain the enhanced ruthenium-plated molybdenum sheet.

[0012] The magnetron sputtering employed in the above technical solution of the present invention is a physical vapor deposition technique that generates high-energy particle bombardment, producing a dense and uniform thin film structure. Through the action of high-energy particles during the sputtering process, the deposited molybdenum layer achieves a smaller grain size and a more refined grain structure, improving the surface condition of the molybdenum sheet itself, reducing the exposure of surface defects, and significantly enhancing the bonding between the molybdenum sheet and the ruthenium coating.

[0013] In the above technical solution, oxidative pickling is to use an oxidizing and acidic solvent to treat the surface of the molybdenum-plated molybdenum sheet, which can enable the molybdenum-plated molybdenum sheet to obtain a certain degree of chemical etching activation. Without excessively etching the surface molybdenum film, the surface roughness of the material is increased, thereby increasing the bonding force between the subsequent ruthenium layer and the molybdenum film. At the same time, oxidative pickling also cleans the molybdenum-plated molybdenum sheet to remove pollutants and oxides on its surface.

[0014] In the above technical solution, the use of an improved anode layer ion source for ion cleaning and activation can effectively avoid the element contamination problem in the large beam and high-speed ion cleaning process, activate the molybdenum-plated molybdenum sheet, and improve the production efficiency of the continuous production process.

[0015] According to some preferred embodiments of the present invention, the oxidative pickling includes: washing the molybdenum-plated molybdenum sheet with aqua regia, and then rinsing with deionized water.

[0016] According to some preferred embodiments of the present invention, the magnetron sputtering process is performed under vacuum, the process temperature is 450° C.-550° C., and the deposition rate is 5-10 nm / min.

[0017] According to some preferred embodiments of the present invention, the sputtering gas pressure of the magnetron sputtering process is 0.1-0.6 Pa, and the sputtering power is 700-1300W.

[0018] According to some preferred embodiments of the present invention, step (1) further comprises: after the magnetron sputtering treatment, cooling the obtained sputtered molybdenum sheet to 55-65° C. in an inert atmosphere cycle to obtain the molybdenum-coated molybdenum sheet.

[0019] According to some preferred embodiments of the present invention, the vapor deposition process is performed under vacuum, the process temperature is 150-250° C., and the deposition rate is 10-20 nm / min.

[0020] According to some preferred embodiments of the present invention, the vapor deposition process is performed in a magnetron sputtering device with a sputtering pressure of 0.1-0.5 Pa and a sputtering power of 800-1200W.

[0021] According to some preferred embodiments of the present invention, the improved anode layer ion source performs the ion cleaning activation at a rate of 150-650 mm / min, a pressure of 0.06-0.8 Pa, and a current of 0.3-2.0 A.

[0022] The above preferred embodiments of the present invention improve the ion source current, thereby increasing the beam current of the anode layer ion source and increasing the cleaning effect per unit time. At the same time, considering that under large beam current conditions, the anode layer ion source will experience more serious cathode etching, and the cathode material will also be mixed into the ion beam and bombarded on the sample surface, causing elemental pollution and affecting the overall performance of the material, and the commonly used solution will reduce the ion source beam current and add a transition section, resulting in problems such as increased equipment length and decreased production efficiency. On the other hand, in the technical solution of the present invention, the base material is high-purity molybdenum, and a small amount of cathode material molybdenum mixed in the ion beam will not cause pollution of the raw materials. Moreover, molybdenum, as a metal with a high melting point and low sputtering rate, can be a good substitute for the currently used stainless steel cathode. Therefore, the present invention can increase the ion source beam current size and cleaning speed without causing raw material pollution and adding a transition section, thereby reducing the equipment length and improving production efficiency.

[0023] The present invention further provides an enhanced ruthenium-plated molybdenum sheet prepared according to the above preparation method.

[0024] The presence of a transition layer between the molybdenum layer and the molybdenum substrate in this reinforced ruthenium-coated molybdenum sheet is primarily due to differences in the crystal state caused by the different preparation methods of the molybdenum layer and the molybdenum substrate. However, there is a clear boundary between the molybdenum layer and the ruthenium layer, with no transition layer present, demonstrating a strong bond, consistent with the low-temperature non-wetting properties of molybdenum and ruthenium.

[0025] The preparation method of the present invention deposits a new molybdenum coating on the surface of the molybdenum sheet by magnetron sputtering, thereby improving the surface condition of the original base molybdenum sheet, filling the microscopic defects of the substrate to make it smoother, and forming a refined and compact molybdenum coating, which significantly improves the deposition conditions of the ruthenium layer and enhances the uniformity of the ruthenium coating and its bonding ability with the molybdenum layer.

[0026] The preparation method of the present invention has low requirements for the molybdenum sheet substrate, and rolled molybdenum sheets can be directly used for plating without the need for grinding the molybdenum sheets.

[0027] The preparation method of the present invention can form a ruthenium plating layer that is firmly attached and tightly combined with a molybdenum sheet substrate, thereby obtaining a reinforced ruthenium-plated molybdenum sheet. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a diagram showing the peeling condition after the 3M tape peeling test of Example 1.

[0029] Figure 2 This is a diagram showing the peeling condition after the 3M tape peeling test of Comparative Example 1.

[0030] Figure 3 This is a diagram showing the peeling condition after the 3M tape peeling test of Comparative Example 2. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below through specific embodiments, but this should not be construed as limiting the scope of the present invention to the following examples. Various substitutions or modifications made according to common technical knowledge and customary means in the art without departing from the above-mentioned method concept of the present invention are intended to be included within the scope of the present invention.

[0032] Example 1

[0033] Prepare ruthenium-coated molybdenum discs by the following steps:

[0034] (1) Place a molybdenum disc with a specification of φ30 mm × T1.4 mm in a cleaning kettle to remove grease and organic pollutants on the surface, and then dry it to obtain a molybdenum disc with a clean surface;

[0035] (2) Place the molybdenum wafer with a clean surface into a magnetron sputtering device, evacuate the vacuum to form a vacuum system, then heat the magnetron sputtering device to 500°C to form a high-temperature system, and deposit molybdenum under the conditions of sputtering pressure of 0.1 Pa and sputtering power of 1000 W for 60 min. Then, cool the temperature to 60°C in a nitrogen atmosphere by gas circulation to obtain a molybdenum wafer with a molybdenum coating thickness of 0.5 μm, i.e., a molybdenum-coated molybdenum wafer;

[0036] (3) The molybdenum-coated molybdenum wafers were oxidized and pickled, and then dried and placed in a magnetron sputtering device for high vacuum to form a vacuum system. The magnetron sputtering device was heated to 200°C to form a high-temperature system, and then ion source cleaning and ruthenium deposition were carried out continuously. The deposition time was 30 min. The gas circulation was cooled to 60°C under a nitrogen atmosphere to obtain a ruthenium-coated molybdenum wafer with a ruthenium layer thickness of 0.5 μm. The specific process of oxidative pickling was as follows: the molybdenum-coated molybdenum wafers were placed in aqua regia for 1-3 min and then washed with deionized water. The specific conditions for ion source cleaning were as follows: cleaning gas pressure 0.2 Pa, cleaning current 2 A, cleaning speed 500 mm / min, and high-purity molybdenum ion source was used for cleaning. The specific conditions for ruthenium deposition were as follows: sputtering gas pressure 0.2 Pa, sputtering power 1000 W.

[0037] Example 2

[0038] Prepare ruthenium-coated molybdenum discs by the following steps:

[0039] (1) Place a molybdenum disc with a specification of φ30 mm*T1.4 mm in a cleaning kettle to remove grease and organic pollutants on the surface, and then dry it to obtain a molybdenum disc with a clean surface;

[0040] (2) Place the molybdenum wafer with a clean surface into a magnetron sputtering device, evacuate the vacuum to form a vacuum system, then heat the magnetron sputtering device to 500°C to form a high-temperature system, and then deposit molybdenum at a sputtering pressure of 0.1 Pa and a power of 1000 W for 60 min. Then, cool the temperature to 60°C in a nitrogen atmosphere by gas circulation to obtain a molybdenum wafer with a molybdenum coating thickness of 0.5 μm, i.e., a molybdenum-coated molybdenum wafer;

[0041] (3) The molybdenum-coated wafers were oxidized and pickled, dried, and placed in a magnetron sputtering device for high vacuum to form a vacuum system. The magnetron sputtering device was heated to 200°C to form a high-temperature system. Then, ion source cleaning and ruthenium deposition were performed continuously. The deposition time was 60 minutes. The gas circulation was cooled to 60°C under a nitrogen atmosphere to obtain a ruthenium-coated molybdenum wafer with a ruthenium layer thickness of 1 μm. The specific process of oxidative pickling was as follows: the molybdenum-coated wafers were placed in aqua regia for 1-3 minutes and then rinsed with deionized water. The specific conditions for ion source cleaning were: cleaning gas pressure 0.2 Pa, cleaning current 2 A, cleaning speed 500 mm / min, and cleaning using a high-purity molybdenum ion source. The specific conditions for ruthenium deposition were: sputtering gas pressure 0.2 Pa, sputtering power 1000 W.

[0042] Example 3

[0043] Prepare ruthenium-coated molybdenum discs by the following steps:

[0044] (1) Place a molybdenum disc with a specification of φ30 mm*T1.4 mm in a cleaning kettle to remove grease and organic pollutants on the surface, and then dry it to obtain a molybdenum disc with a clean surface;

[0045] (2) Place the molybdenum wafer with a clean surface into a magnetron sputtering device, evacuate the vacuum to form a vacuum system, then heat the magnetron sputtering device to 500°C to form a high-temperature system, and then deposit molybdenum at a sputtering pressure of 0.1 Pa and a power of 1000 W for 10 minutes. Then, cool the temperature to 60°C in a nitrogen atmosphere by gas circulation to obtain a molybdenum wafer with a molybdenum coating thickness of 0.1 μm, i.e., a molybdenum-coated molybdenum wafer;

[0046] (3) The molybdenum-coated wafers were oxidized and pickled, dried, and placed in a magnetron sputtering device for high vacuum to form a vacuum system. The magnetron sputtering device was heated to 200°C to form a high-temperature system. Then, ion source cleaning and ruthenium deposition were performed continuously. The deposition time was 60 minutes. The gas circulation was cooled to 60°C under a nitrogen atmosphere to obtain a ruthenium-coated molybdenum wafer with a ruthenium layer thickness of 1 μm. The specific process of oxidative pickling was as follows: the molybdenum-coated wafers were placed in aqua regia for 1-3 minutes and then rinsed with deionized water. The specific conditions for ion source cleaning were: cleaning gas pressure 0.2 Pa, cleaning current 2 A, cleaning speed 500 mm / min, and cleaning using a high-purity molybdenum ion source. The specific conditions for ruthenium deposition were: sputtering gas pressure 0.2 Pa, sputtering power 1000 W.

[0047] The ruthenium-plated molybdenum discs prepared in Examples 1-3 were subjected to a ruthenium coating adhesion test and a 3M tape peeling test, respectively. The results are shown in Table 1:

[0048] Table 1 Test results of coating properties of Examples 1-3

[0049]

[0050] The adhesion of the ruthenium coating is tested using the scratch method, and the process is as follows:

[0051] Using a microscratch tester, a hard diamond stylus is used to scratch the surface of the coating under increasing normal force (pressure) until the coating is damaged. The bond strength is evaluated based on the critical load (N, Newton) at which the coating breaks.

[0052] The 3M tape peel test process is:

[0053] Take a 3M tape of appropriate length and stick it on the coating of the sample to be tested. Press it firmly until there are no bubbles or pores between the tape and the coating. After 10 seconds, peel off the tape with a force perpendicular to the coating direction. Observe whether there is any tearing on the coating surface, film shedding, or whether there is any metal ruthenium stuck on the tape.

[0054] Among them, the ruthenium coating of Example 1 has no peeling phenomenon as shown in the attached figure. Figure 1 shown.

[0055] Ruthenium-plated molybdenum discs were prepared by the same process as in Examples 1-3, except that the magnetron sputtering molybdenum plating process in step (2) was not performed and the ruthenium plating process in step (3) was directly performed to obtain ruthenium-free molybdenum-plated molybdenum discs. The same ruthenium plating adhesion test and 3M tape peeling test as in Examples 1-3 were performed on the discs. The results are shown in Table 2:

[0056] Table 2 Comparative Examples 1-3 Coating Performance Test Results

[0057]

[0058] Among them, the ruthenium coating in Comparative Example 1 is peeled off in large quantities as shown in the attached figure. Figure 2 As shown in the attached figure, the ruthenium plating layer in Comparative Example 2 is partially peeled off. Figure 3 shown.

[0059] The test results show that compared with the molybdenum disc directly plated with ruthenium, the bonding strength between the ruthenium coating and the substrate in the ruthenium-plated molybdenum disc obtained by adding a new molybdenum coating and then plating ruthenium in the present invention is significantly improved.

[0060] The above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions that fall within the scope of protection of the present invention are within the scope of protection of the present invention. It should be noted that improvements and modifications that can be made by a person skilled in the art without departing from the principles of the present invention are also considered to be within the scope of protection of the present invention.

Claims

1. A method for preparing a reinforced ruthenium-plated molybdenum sheet, characterized in that: It includes: (1) Using high-purity molybdenum as a target material, a high-purity molybdenum coating with a thickness of 0.1 to 0.5 μm is plated on the surface of the molybdenum sheet by magnetron sputtering to obtain a molybdenum-coated molybdenum sheet; (2) oxidizing and pickling the molybdenum-plated sheet to obtain a pickled molybdenum-plated sheet; (3) performing ion cleaning and activation on the molybdenum-plated molybdenum sheet after pickling by using an improved anode layer ion source to obtain an activated molybdenum-plated molybdenum sheet, wherein the improved anode layer ion source is obtained by replacing the inner cathode and outer cathode materials of the ordinary anode layer ion source with high-purity molybdenum; (4) Depositing a ruthenium coating layer with a thickness of 0.5 to 1 μm on the surface of the activated molybdenum-plated molybdenum sheet through vapor deposition to obtain the enhanced ruthenium-plated molybdenum sheet.

2. The preparation method according to claim 1, characterized in that The oxidative pickling comprises: washing the molybdenum-plated molybdenum sheet with aqua regia, and then rinsing with deionized water.

3. The preparation method according to claim 1, characterized in that The magnetron sputtering process is carried out under vacuum, the process temperature is 450° C.-550° C., and the deposition rate is 5-10 nm / min.

4. The preparation method according to claim 1, characterized in that The sputtering gas pressure of the magnetron sputtering process is 0.1-0.6 Pa, and the sputtering power is 700-1300W.

5. The preparation method according to claim 1, characterized in that Step (1) further comprises: after the magnetron sputtering treatment, cooling the obtained sputtered molybdenum sheet to 55-65° C. in an inert atmosphere cycle to obtain the molybdenum-coated molybdenum sheet.

6. The preparation method according to claim 1, characterized in that The vapor deposition process is carried out under vacuum, the process temperature is 150-250° C., and the deposition rate is 10-20 nm / min.

7. The preparation method according to claim 1, characterized in that The vapor deposition process is carried out in a magnetron sputtering device with a sputtering pressure of 0.1-0.5 Pa and a sputtering power of 800-1200 W.

8. The preparation method according to claim 7, wherein The improved anode layer ion source performs the ion cleaning activation at a rate of 150-650 mm / min, a pressure of 0.06-0.8 Pa, and a current of 0.3-2.0 A.

9. The enhanced ruthenium-plated molybdenum sheet prepared by the preparation method according to any one of claims 1 to 8.

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