A copper contact coating process based on the magnetron sputtering method

Abstract

The present invention belongs to the technical field of material surface treatment, and particularly relates to a copper contact coating process based on a magnetron sputtering method; the present invention improves the pretreatment process of copper contacts, making the surface of copper contacts smooth and bright through mechanical polishing, solvent cleaning, and pickling; and a titanium nitride layer and a silver-iridium-cerium mixed metal layer are sequentially deposited on the surface of the copper contacts, improving the hardness of the copper contacts; the process of the present invention has few process steps and high efficiency, and the obtained coating has high hardness and good adhesion.

Description

Technical Field

[0001] The present invention belongs to the technical field of material surface treatment, and particularly relates to a copper contact coating process based on a magnetron sputtering method. Background Art

[0002] Due to characteristics such as good electrical conductivity and relatively low cost, copper metal has become a commonly used material for manufacturing electrical contacts. However, in air, copper will form copper oxide due to the action of electric arcs during repeated connection and disconnection processes, reducing the contact resistance of the electrical contacts and shortening the service life of the electrical contacts. To ensure its high reliability, generally, a protective film is plated on the contact part of the electrical contacts to reduce the contact resistance, prevent the contacts from oxidizing, and improve its electrical conductivity.

[0003] Currently, the commonly used coating method is cyanide plating. The cyanide plating process has good stability, and the properties such as the contact resistance and adhesion of the coating are good. However, cyanide is highly toxic, easily harmful to the human body, and pollutes the environment.

[0004] Chinese patent application document with application publication number CN102560451A discloses a chemical plating nano - silver solution, a preparation method thereof, and a method for silver plating on copper parts. The mass concentrations of the components in the raw material formula of the chemical plating silver solution are as follows: plating solution A: silver salt 1 - 20 g / L, ammonia water with a mass concentration of 25% 3 - 50 g / L; plating solution B: reducing agent 3 - 105 g / L, organic additive 0.05 - 1 g / L, other additives 0.01 - 0.2 g / L. This technical solution solves the problem of low stability of the chemical plating solution. The prepared plating solution has good stability, and a bright and delicate nano - silver coating is formed on the copper surface, with excellent performance.

[0005] However, the hardness of silver is relatively low. During actual use, especially in the case of frequent plugging and unplugging or friction, the silver - plated layer is prone to wear, resulting in the thinning of the silver layer or even exposing the base copper, affecting the performance of the product. Summary of the Invention

[0006] There is a problem of low hardness in the existing coatings; to solve this problem, the present invention provides a copper contact coating process based on a magnetron sputtering method.

[0007] To achieve the object of the present invention, the following technical solutions are adopted in the present invention:

[0008] The present invention provides a copper contact coating process based on a magnetron sputtering method, including the following steps:

[0009] (1) Pretreat the surface of the copper contact substrate. The pretreatment includes mechanical polishing, solvent cleaning, and pickling to obtain the pretreated copper contact substrate;

[0010] (2) Transfer the pre-treated copper contact substrate into a vacuum furnace, evacuate to the background vacuum degree, introduce argon gas and adjust the air pressure, and carry out glow cleaning to obtain the copper contact substrate after glow cleaning;

[0011] (3) Evacuate to the background vacuum degree, introduce argon gas, and deposit a titanium nitride layer on the surface of the copper contact substrate after glow cleaning by magnetron sputtering to obtain the copper contact substrate deposited with a titanium nitride layer;

[0012] (4) Evacuate to the background vacuum degree, introduce argon gas, deposit a silver-iridium-cerium mixed metal layer on the surface of the copper contact substrate deposited with a titanium nitride layer by magnetron sputtering, end the deposition, and obtain the sample;

[0013] (5) Anneal the sample to obtain the copper contact.

[0014] Preferably, in the step (1), after the surface of the copper contact substrate is mechanically polished to a surface roughness Ra of 0.2 μm to 0.5 μm, it is placed in an ethanol solvent and ultrasonically cleaned for 5 to 10 minutes, then placed in a propanol solvent and ultrasonically cleaned for 15 to 20 minutes, and then placed in an acid solution and soaked for 3 to 5 minutes, washed with water, and dried with nitrogen.

[0015] By adopting the above technical solutions, mechanical polishing can improve the surface flatness and smoothness of the copper contact substrate, reduce the surface roughness, and help the coating particles to be evenly deposited on the surface of the copper contact substrate; solvent cleaning can remove pollutants such as oil, grease, and dust on the surface of the copper contact substrate, and pickling can remove surface oxides and other metal impurities, but the pickling time should not be too long, otherwise over-pickling will cause the surface of the copper contact to be rough or over-corroded.

[0016] Preferably, the acid solution is composed of the following components in parts by mass:

[0017] 3 to 8 parts of hydrochloric acid, 8 to 15 parts of citric acid, 2 to 5 parts of hydroxyethylidene diphosphonic acid, 1 to 3 parts of ethylenediaminetetraacetic acid, 0.5 to 1 part of thiourea, 0.1 to 0.2 part of polyvinylpyrrolidone, 45 to 55 parts of water.

[0018] By adopting the above technical solutions, this component can ensure the protection of the copper contact substrate while effectively cleaning. Citric acid and hydrochloric acid form a composite acid type acid solution, providing an acidic environment and improving the removal ability of surface oxides and impurities of the copper contact substrate; hydroxyethylidene diphosphonic acid and ethylenediaminetetraacetic acid have good chelating properties, which can avoid the re-deposition of other metal ions on the copper contact surface during the cleaning process and cause secondary pollution; thiourea can slow down the corrosion rate of the acid solution on copper; polyvinylpyrrolidone can prevent dirt particles from re-aggregating on the copper surface and improve the cleaning ability.

[0019] Preferably, the background vacuum degree is 1×10 -4 ~1×10-5 Pa.

[0020] Preferably, in the step (2), the flow rate of argon is 120 - 150 Sccm, the voltage of the bias power supply used for glow cleaning is -500 - -600 V, the duty cycle is 50% - 70%, and the time for glow cleaning is 10 - 20 min.

[0021] Preferably, in the step (3), the flow rate of argon is 30 - 80 Sccm.

[0022] Preferably, in the step (3), the deposition process of the titanium nitride layer is as follows: the target for depositing the titanium nitride layer is a titanium nitride target with a purity of 99.999%, the DC power of the titanium nitride target is 100 - 200 W, the deposition pressure is 0.3 - 1 Pa, the voltage of the bias power supply is -50 - -150 V, and the deposition time is 5 - 20 min.

[0023] By adopting the above technical solution, a high - purity titanium nitride target can ensure that the surface of the coating is flat, without obvious defects and impurities; the titanium nitride thin film prepared within this parameter range is smooth and dense.

[0024] Preferably, in the step (4), the flow rate of argon is 150 - 180 sccm.

[0025] Preferably, in the step (4), the deposition process of the silver - iridium - cerium mixed metal layer is as follows: the targets for depositing the silver - iridium - cerium mixed metal layer are a silver target, an iridium target, and a cerium target. The DC power of the silver target is 150 - 300 W, the DC power of the iridium target is 50 - 150 W, the DC power of the cerium target is 50 - 80 W, the deposition pressure is 0.5 - 1 Pa, the voltage of the bias power supply is -50 - -150 V, and the deposition time is 60 - 80 min.

[0026] Preferably, the number ratio of the silver target, the iridium target, and the cerium target is 3:1:1.

[0027] By adopting the above technical solution, the conductivity advantage of silver can be fully exerted under this ratio, and a small amount of iridium and cerium can improve the hardness and antioxidant performance of the contact to a certain extent.

[0028] Preferably, in the step (5), the annealing atmosphere is 20% hydrogen and 80% argon, the annealing temperature is 350 - 550 °C, and the annealing time is 2 - 4 h; "20%" and "80%" are "20 wt%" and "80 wt%".

[0029] By adopting the above technical solution, annealing in this atmosphere can make the crystal structure of the silver - iridium - cerium thin film more complete, reduce defects and lattice distortion, and make the conductivity of the copper contact better.

[0030] In summary, the beneficial effects of the present invention are as follows:

[0031] (1) The present invention improves the pretreatment process of copper contacts. Through mechanical polishing, solvent cleaning, and pickling, the surface of the copper contacts becomes smooth and bright. A titanium nitride layer and a silver-iridium-cerium mixed metal layer are sequentially deposited on the surface of the copper contacts, improving the hardness of the copper contacts. The process of the present invention has fewer process steps and high efficiency, and the obtained coating has high hardness and good adhesion.

[0032] (2) The acid solution compounded in the present invention can quickly remove the dirt on the surface of the copper contacts without over-corroding the copper contacts. The cleaning efficiency is high, and it can provide a uniform substrate for subsequent magnetron sputtering coating.

[0033] (3) Depositing a titanium nitride layer on the surface of the copper contacts in the present invention can form a good combination with the copper contacts. At the same time, it provides a transition layer for the subsequent deposition of the silver-iridium-cerium mixed metal layer. Silver can form a good combination with the titanium nitride layer, enabling the overall adhesion to be improved through the transition effect of the titanium nitride layer between copper and silver, reducing the bonding defects and weak points at the copper-silver interface, and avoiding problems such as delamination and peeling during long-term use.

[0034] (4) Introducing iridium and cerium into the silver plating layer in the present invention. The addition of cerium can refine the grains of silver, producing a solid solution strengthening effect, making the microstructure of the coating more uniform and dense. Iridium has a higher hardness, which can increase the hardness of the silver plating layer, enhance the wear resistance of the copper contacts, and prevent problems such as deformation and wear during frequent use. Brief Description of the Drawings

[0035] Figure 1 It is a schematic appearance view of the copper contacts prepared in Example 1 of the present invention;

[0036] Figure 2 It is a SEM morphology diagram of the copper contacts prepared in Example 1 of the present invention;

[0037] Figure 3 It is a SEM morphology diagram of the copper contacts prepared in Comparative Example 3 of the present invention. Detailed Embodiments

[0038] The technical solutions of the present invention will be described in detail below with reference to several representative embodiments of the present invention.

[0039] Materials, reagents, etc. used in the following examples and comparative examples can be obtained from commercial sources without special instructions.

[0040] The purity of the titanium nitride target, titanium oxide target, titanium target, silver target, iridium target, cerium target, and indium target used in the following examples and comparative examples is 99.999%.

[0041] Example 1

[0042] The acid solution in this embodiment is composed of components with the following masses:

[0043] 3 g of hydrochloric acid, 10 g of citric acid, 3 g of hydroxyethylidene diphosphonic acid, 2 g of ethylenediaminetetraacetic acid, 0.8 g of thiourea, 0.1 g of polyvinylpyrrolidone, and 45 g of water.

[0044] A copper contact coating process based on the magnetron sputtering method in this embodiment is as follows:

[0045] (1) Pretreat the surface of the copper contact substrate. After mechanically polishing the surface of the copper contact substrate to a surface roughness Ra of 0.3 μm, place the copper contact substrate in an ethanol solvent and clean it for 10 min under ultrasonic conditions, then clean it in a propanol solvent for 18 min under ultrasonic conditions, then soak it in the acid solution for 3 min, take it out, rinse it with deionized water for 20 min, and dry it with nitrogen to obtain the pretreated copper contact substrate.

[0046] (2) Transfer the pretreated copper contact substrate into a vacuum furnace. Load a titanium nitride target, three silver targets, an iridium target, and a cerium target into the sputtering chamber, and evacuate the sputtering chamber to a base vacuum of 1×10 -4 Pa, introduce 130 Sccm of argon gas, set the voltage of the bias power supply to -550 V, the duty cycle to 50%, and the glow cleaning time to 15 min to obtain the copper contact substrate after glow cleaning.

[0047] (3) After the copper contact substrate is glow cleaned, evacuate the vacuum furnace to a base vacuum of 1×10 -4 Pa, introduce 30 sccm of argon gas, adjust the air pressure to 0.8 Pa, the rotation speed of the turntable to 3 r / min, control the DC sputtering power of the titanium nitride target to 150 W, and the voltage of the bias power supply to -100 V, and start depositing a titanium nitride layer on the glow-cleaned copper contact substrate for 10 min to obtain the copper contact substrate deposited with a titanium nitride layer.

[0048] (4) After the titanium nitride layer is formed, stop depositing the titanium nitride target; evacuate the vacuum furnace to a base vacuum of 1×10 -4 Pa, introduce 150 sccm of argon gas, adjust the air pressure to 0.5 Pa, the rotation speed of the turntable to 3 r / min, control the DC power of the silver target to 150 W, the DC power of the iridium target to 100 W, and the DC power of the cerium target to 60 W, and deposit a silver-iridium-cerium mixed metal layer on the copper contact substrate deposited with a titanium nitride layer for 60 min, and end the deposition to obtain the sample.

[0049] (5) Place the sample in a tube furnace for annealing. The annealing atmosphere is 20 wt% hydrogen and 80 wt% argon. The heating rate is 5 °C / min, the annealing temperature is 400 °C, and the annealing time is 3 h. After cooling to room temperature with the furnace, a copper contact is obtained. The surface of the copper contact is smooth and dense. The schematic diagram of the appearance of the copper contact is shown in Figure 1 , and the SEM morphology diagram of the copper contact is shown in Figure 2 ; It can be seen from Figure 2 that the film layer prepared in Example 1 is relatively smooth and flat, and almost no obvious particle structure can be seen, indicating that atoms spread evenly during the deposition process, forming a smooth and dense surface morphology.

[0050] Example 2

[0051] The acid solution in this example consists of the following components by mass:

[0052] 5 g hydrochloric acid, 12 g citric acid, 2 g hydroxyethylidene diphosphonic acid, 1 g ethylenediaminetetraacetic acid, 0.6 g thiourea, 0.2 g polyvinylpyrrolidone, 55 g water.

[0053] A copper contact coating process based on magnetron sputtering method in this example is as follows:

[0054] (1) Pretreat the surface of the copper contact substrate. After mechanically polishing the surface of the copper contact substrate to a surface roughness Ra of 0.5 μm, place the copper contact substrate in an ethanol solvent for 10 min under ultrasonic conditions, then in a propanol solvent for 20 min under ultrasonic conditions, then soak it in the acid solution for 3 min, take it out and rinse it with deionized water for 20 min, and dry it with nitrogen to obtain a pretreated copper contact substrate;

[0055] (2) Transfer the pretreated copper contact substrate into a vacuum furnace. Install a titanium nitride target, three silver targets, an iridium target, and a cerium target in the sputtering chamber, and evacuate the sputtering chamber to a base vacuum of 1×10 -4 Pa, introduce 120 Sccm of argon, set the voltage of the bias power supply to -600 V, the duty cycle to 70%, and the glow cleaning time to 20 min to obtain a glow-cleaned copper contact substrate;

[0056] (3) After the copper contact substrate is glow-cleaned, evacuate the vacuum furnace to a base vacuum of 1×10 -4 Pa, introduce 80 sccm of argon, adjust the gas pressure to 0.3 Pa, the turntable rotation speed to 3 r / min, control the DC sputtering power of the titanium nitride target to 100 W, and the voltage of the bias power supply to -150 V, and start depositing a titanium nitride layer on the glow-cleaned copper contact substrate for 15 min to obtain a copper contact substrate deposited with a titanium nitride layer;

[0057] (4) After the titanium nitride layer is formed, stop depositing the titanium nitride target; evacuate the vacuum furnace to the base vacuum of 1×10 -4 Pa, introduce 150 sccm of argon gas, adjust the air pressure to 0.6 Pa, the rotation speed of the turntable is 3 r / min, control the DC power of the silver target to be 300 W, the DC power of the iridium target to be 150 W, and the DC power of the cerium target to be 80 W. Deposit a silver-iridium-cerium mixed metal layer on the copper contact substrate with the deposited titanium nitride layer for 80 min, end the deposition, and obtain the sample;

[0058] (5) Put the sample into a tube furnace for annealing treatment. The annealing atmosphere is 20 wt% hydrogen and 80 wt% argon. The heating rate is 5 °C / min, the annealing temperature is 350 °C, and the annealing time is 2 h. After cooling to room temperature with the furnace, obtain the copper contact.

[0059] Example 3

[0060] The acid solution in this example consists of the following components by mass:

[0061] 3 g of hydrochloric acid, 8 g of citric acid, 5 g of hydroxyethylidene diphosphonic acid, 3 g of ethylenediaminetetraacetic acid, 0.5 g of thiourea, 0.2 g of polyvinylpyrrolidone, and 50 g of water.

[0062] A copper contact coating process based on the magnetron sputtering method in this example is as follows:

[0063] (1) Pretreat the surface of the copper contact substrate. After mechanically polishing the surface of the copper contact substrate to a surface roughness Ra of 0.2 μm, place the copper contact substrate in an ethanol solvent for 5 min under ultrasonic conditions, then clean it in a propanol solvent for 15 min under ultrasonic conditions, then immerse it in the acid solution for 4 min, take it out and rinse it with deionized water for 20 min, and dry it with nitrogen to obtain the pretreated copper contact substrate;

[0064] (2) Transfer the pretreated copper contact substrate into a vacuum furnace. Load a titanium nitride target, three silver targets, an iridium target, and a cerium target into the sputtering cavity, and evacuate the sputtering cavity to the base vacuum of 1×10 -5 Pa, introduce 150 Sccm of argon gas, set the voltage of the bias power supply to -500 V, the duty cycle to 60%, and the glow cleaning time to 15 min to obtain the glow-cleaned copper contact substrate;

[0065] (3) After the copper contact substrate is glow-cleaned, evacuate the vacuum furnace to the base vacuum of 1×10 -5Introduce argon at 50 sccm, adjust the air pressure to 0.6 Pa, the rotation speed of the turntable to 3 r / min, control the power of the DC sputtering power supply of the titanium nitride target to 200 W, and the voltage of the bias power supply to -50 V. Then start depositing a titanium nitride layer on the copper contact substrate after glow cleaning for 5 minutes to obtain a copper contact substrate with a deposited titanium nitride layer.

[0066] (4)After the titanium nitride layer is formed, stop depositing the titanium nitride target; evacuate the vacuum furnace to the base vacuum of 1×10 -5 Pa, introduce argon at 180 sccm, adjust the air pressure to 0.8 Pa, the rotation speed of the turntable to 3 r / min, control the power of the DC power supply of the silver target to 250 W, the power of the DC power supply of the iridium target to 80 W, and the power of the DC power supply of the cerium target to 80 W. Deposit a silver-iridium-cerium mixed metal layer on the copper contact substrate with a deposited titanium nitride layer for 80 minutes, end the deposition, and obtain the sample.

[0067] (5)Put the sample into a tube furnace for annealing treatment. The annealing atmosphere is 20 wt% hydrogen and 80 wt% argon, the heating rate is 5 °C / min, the annealing temperature is 550 °C, and the annealing time is 4 h. After cooling to room temperature with the furnace, obtain the copper contact.

[0068] Example 4

[0069] The acid solution in this example consists of components with the following masses:

[0070] 8 g hydrochloric acid, 15 g citric acid, 2 g hydroxyethylidene diphosphonic acid, 1 g ethylenediaminetetraacetic acid, 1 g thiourea, 0.1 g polyvinylpyrrolidone, 55 g water.

[0071] A copper contact coating process based on a magnetron sputtering method in this example is as follows:

[0072] (1)Pretreat the surface of the copper contact substrate. After mechanically polishing the surface of the copper contact substrate to a surface roughness Ra of 0.3 μm, place the copper contact substrate in an ethanol solvent under ultrasonic conditions for 8 minutes, then in a propanol solvent under ultrasonic conditions for 15 minutes, then soak it in the acid solution for 5 minutes, take it out and rinse it with deionized water for 20 minutes, and dry it with nitrogen to obtain a pretreated copper contact substrate.

[0073] (2)Transfer the pretreated copper contact substrate into a vacuum furnace, load a titanium nitride target, three silver targets, an iridium target, and a cerium target in the sputtering cavity, and evacuate the sputtering cavity to the base vacuum of 1×10 -5 Pa, introduce argon at 135 Sccm, set the voltage of the bias power supply to -600 V, the duty cycle to 60%, and the glow cleaning time to 10 minutes to obtain a copper contact substrate after glow cleaning.

[0074] (3) After the copper contact substrate is glow-cleaned, evacuate the vacuum furnace to the base vacuum of 1×10 -5 Pa, introduce argon gas at 50 sccm, adjust the air pressure to 1 Pa, the rotation speed of the turntable is 3 r / min, control the DC sputtering power supply power of the titanium nitride target to be 100 W, the voltage of the bias power supply is -100 V, and start depositing a titanium nitride layer on the glow-cleaned copper contact substrate for 20 min to obtain a copper contact substrate deposited with a titanium nitride layer;

[0075] (4) After the titanium nitride layer is formed, stop depositing the titanium nitride target; evacuate the vacuum furnace to the base vacuum of 1×10 -5 Pa, introduce argon gas at 180 sccm, adjust the air pressure to 1 Pa, the rotation speed of the turntable is 3 r / min, control the DC power supply power of the silver target to be 200 W, the DC power supply power of the iridium target to be 120 W, the DC power supply power of the cerium target to be 50 W, and deposit a silver-iridium-cerium mixed metal layer on the copper contact substrate deposited with the titanium nitride layer for 60 min, end the deposition, and obtain a sample;

[0076] (5) Put the sample into a tube furnace for annealing treatment. The annealing atmosphere is 20 wt% hydrogen and 80 wt% argon, the heating rate is 5 °C / min, the annealing temperature is 500 °C, and the annealing time is 4 h. After cooling to room temperature with the furnace, a copper contact is obtained.

[0077] Example 5

[0078] The acid solution in this example is composed of components with the following masses:

[0079] 7 g of hydrochloric acid, 8 g of citric acid, 4 g of hydroxyethane diphosphonic acid, 3 g of ethylenediaminetetraacetic acid, 1 g of thiourea, 0.2 g of polyvinylpyrrolidone, 50 g of water.

[0080] A copper contact coating process based on a magnetron sputtering method in this example is as follows:

[0081] (1) Pretreat the surface of the copper contact substrate. After mechanically polishing the surface of the copper contact substrate to a surface roughness Ra of 0.5 μm, place the copper contact substrate in an ethanol solvent for 5 min under ultrasonic conditions, then clean it in a propanol solvent for 20 min under ultrasonic conditions, then soak it in the acid solution for 5 min, take it out, rinse it with deionized water for 20 min, and dry it with nitrogen to obtain a pretreated copper contact substrate;

[0082] (2) Transfer the pretreated copper contact substrate into a vacuum furnace, install a titanium nitride target, three silver targets, an iridium target, and a cerium target in the sputtering cavity, and evacuate the sputtering cavity to the base vacuum of 1×10 -5Pa, introduce 140 sccm of argon gas, set the voltage of the bias power supply to -500 V, the duty cycle to 70%, and the glow cleaning time to 20 min to obtain the copper contact substrate after glow cleaning;

[0083] (3) After the copper contact substrate is glow cleaned, evacuate the vacuum furnace to the base vacuum of 1×10 -5 Pa, introduce 60 sccm of argon gas, adjust the gas pressure to 0.5 Pa, the rotation speed of the turntable to 3 r / min, control the power of the DC sputtering power supply of the titanium nitride target to 150 W, the voltage of the bias power supply to -150 V, and start depositing a titanium nitride layer on the copper contact substrate after glow cleaning for 20 min to obtain the copper contact substrate deposited with a titanium nitride layer;

[0084] (4) After the titanium nitride layer is formed, stop depositing the titanium nitride target; evacuate the vacuum furnace to the base vacuum of 1×10 -5 Pa, introduce 150 sccm of argon gas, adjust the gas pressure to 0.8 Pa, the rotation speed of the turntable to 3 r / min, control the power of the DC power supply of the silver target to 220 W, the power of the DC power supply of the iridium target to 90 W, and the power of the DC power supply of the cerium target to 70 W, and deposit a silver-iridium-cerium mixed metal layer on the copper contact substrate deposited with a titanium nitride layer for 70 min to end the deposition and obtain the sample;

[0085] (5) Put the sample into a tube furnace for annealing treatment. The annealing atmosphere is 20 wt% hydrogen and 80 wt% argon, the heating rate is 5 °C / min, the annealing temperature is 450 °C, and the annealing time is 3 h. After cooling to room temperature with the furnace, obtain the copper contact.

[0086] Comparative Example 1

[0087] The difference from Example 1 is that in this comparative example, the components of the acid solution are adjusted, as shown in Table 1 for details, and the rest are the same as in Example 1.

[0088] Table 1 Components of the acid solution

[0089]

[0090] Comparative Example 2

[0091] The difference from Example 1 is that in this comparative example, a titanium oxide target is used to replace the titanium nitride target, and the rest are the same as in Example 1.

[0092] Comparative Example 3

[0093] The difference from Example 1 is that in this comparative example, a titanium target is used to replace the titanium nitride target, introduce 30 sccm of argon gas and 20 sccm of nitrogen gas to replace introducing 30 sccm of argon gas, and the rest are the same as in Example 1. The SEM morphology diagram of the copper contact prepared in Comparative Example 3 is shown in Figure 3 .

[0094] Comparative Example 4

[0095] It is different from Example 1 in that the deposition of the titanium nitride layer is not carried out in this comparative example, and the rest is the same as in Example 1.

[0096] Comparative Example 5

[0097] It is different from Example 1 in that a silver metal layer is deposited on the titanium nitride layer of the copper contact matrix in this comparative example, and the rest is the same as in Example 1.

[0098] Comparative Example 6

[0099] It is different from Example 1 in that a silver-iridium mixed metal layer is deposited on the titanium nitride layer of the copper contact matrix in this comparative example, and the rest is the same as in Example 1.

[0100] Comparative Example 7

[0101] It is different from Example 1 in that a silver-cerium mixed metal layer is deposited on the titanium nitride layer of the copper contact matrix in this comparative example, and the rest is the same as in Example 1.

[0102] Comparative Example 8

[0103] It is different from Example 1 in that an indium target is used to replace the iridium target in this comparative example, and the rest is the same as in Example 1.

[0104] Related performance tests

[0105] Perform related performance tests on the copper contacts prepared in Examples 1 - 5 and Comparative Examples 1 - 8: Resistivity test: Calculate the resistivity of the copper contacts using the four-probe method; Adhesion test: Place each copper contact in a high-temperature and high-humidity environment for 48 h, stick the tape on the surface of each copper contact and then tear off the tape to check the peeling situation; Hardness test: Use a nano-indentation instrument to test the nano-hardness of the samples, measure each copper contact 5 times, and take the average value; The test results are shown in Table 2.

[0106] Table 2 Test results

[0107]

[0108] It can be seen from the comparison between Comparative Example 1 and Example 1 that Comparative Example 1 changed the components of the acid solution, but the performance of the prepared copper contacts deteriorated, indicating that the components and dosage ratios of the acid solution in the present invention have been optimized.

[0109] It can be seen from the comparison between Comparative Example 2 and Example 1 that the resistivity of titanium oxide is relatively high, and when used as a transition layer, it will increase the overall resistance of the contacts to a certain extent; while when titanium nitride is used as a transition layer, the influence on the overall resistivity of the contacts is relatively small.

[0110] It can be seen from the comparison between Comparative Example 3 and Example 1 that Comparative Example 3 changed the deposition method of the titanium nitride thin film; combined with Figure 3 it can be known that the film layer prepared in Comparative Example 3 has no obvious defects, but shows a relatively rough texture and there are many tiny particle structures, indicating that atomic clusters aggregate during the deposition process. The quality of the titanium nitride thin film formed by depositing with a metal titanium target in a nitrogen and argon atmosphere is uneven and the surface is rough; the rough film surface and particle structures increase electron scattering, affecting the conductivity of the copper contact. At the same time, the rough particles are prone to stress concentration when subjected to external forces, resulting in a decrease in the adhesion and hardness of the film layer. Therefore, the performance of the copper contact prepared is inferior to that of the copper contact directly deposited using a titanium nitride target.

[0111] It can be seen from the comparison between Comparative Example 4 and Example 1 that the presence of the titanium nitride layer has little effect on the resistivity, but the titanium nitride layer can improve the hardness of the contact; at the same time, as a transition layer, it can improve the overall bonding force.

[0112] It can be seen from the comparison between Comparative Examples 5, 6, 7 and Example 1 that the compounding among the three elements of silver, iridium and cerium makes the performance of the copper contact reach the best.

[0113] It can be seen from the comparison between Comparative Example 8 and Example 1 that the addition of indium has little effect on the resistivity, but indium has a lower hardness compared with iridium. Therefore, the improvement of the hardness of the copper contact by the addition of indium is limited.

[0114] The above has made an exemplary description of the present invention. It should be noted that without departing from the core of the present invention, any simple deformation, modification or equivalent replacement that can be made by those skilled in the art without creative labor falls within the protection scope of the present invention.

Claims

1. A copper contact coating process based on a magnetron sputtering method, characterized in that, It includes the following steps: (1) Pretreat the surface of the copper contact substrate, and the pretreatment includes mechanical polishing, solvent cleaning and pickling to obtain the pretreated copper contact substrate; (2) Transfer the pretreated copper contact substrate into a vacuum furnace, evacuate to the background vacuum degree, introduce argon and adjust the air pressure, and perform glow cleaning to obtain the copper contact substrate after glow cleaning; (3) Evacuate to the background vacuum degree, introduce argon, and deposit a titanium nitride layer on the surface of the copper contact substrate after glow cleaning by magnetron sputtering to obtain the copper contact substrate deposited with the titanium nitride layer; (4) Evacuate to the background vacuum degree, introduce argon, deposit a silver-iridium-cerium mixed metal layer on the surface of the copper contact substrate deposited with the titanium nitride layer by magnetron sputtering, and end the deposition to obtain a sample; (5) Anneal the sample to obtain a copper contact; In the step (1), after the surface of the copper contact substrate is mechanically polished to a surface roughness Ra of 0.2 μm to 0.5 μm, it is placed in an ethanol solvent for ultrasonic cleaning for 5 to 10 minutes, then placed in a propanol solvent for ultrasonic cleaning for 15 to 20 minutes, and then placed in an acid solution for soaking for 3 to 5 minutes, washed with water, and dried with nitrogen; The acid solution is composed of the following components in parts by mass: 3 to 8 parts of hydrochloric acid, 8 to 15 parts of citric acid, 2 to 5 parts of hydroxyethylidene diphosphonic acid, 1 to 3 parts of ethylenediaminetetraacetic acid, 0.5 to 1 part of thiourea, 0.1 to 0.2 part of polyvinylpyrrolidone, and 45 to 55 parts of water; In the step (3), the target for depositing the titanium nitride layer is a titanium nitride target.

2. The copper contact coating process based on the magnetron sputtering method according to claim 1, wherein, In the step (2), the flow rate of argon is 120 to 150 sccm; the voltage of the bias power supply used for glow cleaning is -500 to -600 V, the duty cycle is 50% to 70%, and the glow cleaning time is 10 to 20 minutes.

3. A copper contact coating process based on a magnetron sputtering method according to claim 1, characterized in that, In the step (3), the flow rate of argon is 30 to 80 sccm.

4. A copper contact coating process based on a magnetron sputtering method according to claim 1, wherein In the step (3), the deposition process of the titanium nitride layer is: the target for depositing the titanium nitride layer is a titanium nitride target with a purity of 99.999%, the DC power of the titanium nitride target is 100 to 200 W, the deposition air pressure is 0.3 to 1 Pa, the voltage of the bias power supply is -50 to -150 V, and the deposition time is 5 to 20 minutes.

5. A copper contact plating process based on a magnetron sputtering method according to claim 1, characterized in that, In the step (4), the flow rate of argon is 150 to 180 sccm.

6. A copper contact plating process based on a magnetron sputtering method according to claim 1, characterized in that, In the step (4), the deposition process of the silver-iridium-cerium mixed metal layer is: the targets for depositing the silver-iridium-cerium mixed metal layer are a silver target, an iridium target and a cerium target, the DC power of the silver target is 150 to 300 W, the DC power of the iridium target is 50 to 150 W, and the DC power of the cerium target is 50 to 80 W; the deposition air pressure is 0.5 to 1 Pa, the voltage of the bias power supply is -50 to -150 V, and the deposition time is 60 to 80 minutes.

7. A copper contact coating process based on a magnetron sputtering method according to claim 6, characterized in that The number ratio of the silver target, the iridium target and the cerium target is 3∶1∶1.

8. A copper contact plating process based on a magnetron sputtering method according to claim 1, characterized in that, In the step (5), the annealing atmosphere is 20% hydrogen and 80% argon, the annealing temperature is 350 to 550 °C, and the annealing time is 2 to 4 h.

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