Copper contact coating process based on magnetron sputtering method

Abstract

The 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 pretreatment process of the copper contact is improved, and the surface of the copper contact is smooth and bright through mechanical polishing, solvent cleaning and acid pickling; the titanium nitride layer and the silver-iridium-cerium mixed metal layer are sequentially deposited on the surface of the copper contact, so that the hardness of the copper contact is improved; the process is few in procedure and high in efficiency, and the obtained plating layer is high in hardness and good in binding force.

Description

Technical Field

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

[0002] Copper metal is a common material for manufacturing electrical contacts due to its good electrical conductivity and relatively low cost. However, copper in the air will form copper oxide due to the arc during repeated connection and disconnection, which will reduce the contact resistance of the electrical contacts and shorten the service life of the electrical contacts. In order to ensure its high reliability, a protective film is usually plated on the contact part of the electrical contacts to reduce the contact resistance, prevent contact oxidation, and improve its conductivity.

[0003] Currently, the commonly used coating method is cyanide plating. Cyanide plating has good process stability, contact resistance, adhesion and other properties of the coating, but cyanide is highly toxic and can easily cause harm to the human body and pollute the environment.

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

[0005] However, silver has a low hardness. In actual use, especially when frequently plugged in or out or there is friction, the silver-plated layer is prone to wear, causing the silver layer to become thinner or even expose the base copper, affecting the performance of the product. Summary of the invention

[0006] The existing coating has the problem of low hardness. In order to solve this problem, the present invention provides a copper contact coating process based on a magnetron sputtering method.

[0007] In order to achieve the purpose of the present invention, the present invention adopts the following technical solutions: The present invention provides a copper contact coating process based on a magnetron sputtering method, comprising the following steps: (1) Pre-treating the surface of the copper contact substrate, wherein the pre-treatment includes mechanical polishing, solvent cleaning and pickling to obtain a pre-treated copper contact substrate; (2) transferring the pretreated copper contact substrate into a vacuum furnace, evacuating the furnace to a background vacuum, introducing argon gas and adjusting the gas pressure, and performing glow cleaning to obtain a glow-cleaned copper contact substrate; (3) evacuating the gas to a background vacuum, introducing argon gas, and using magnetron sputtering to deposit a titanium nitride layer on the surface of the glow-cleaned copper contact substrate to obtain a copper contact substrate on which a titanium nitride layer is deposited; (4) evacuating the gas to the background vacuum, introducing argon gas, and using magnetron sputtering to deposit a silver-iridium-cerium mixed metal layer on the surface of the copper contact substrate on which the titanium nitride layer was deposited, and then completing the deposition to obtain a sample; (5) The sample is annealed to obtain copper contacts.

[0008] Preferably, in step (1), the surface of the copper contact substrate is mechanically polished to a surface roughness Ra of 0.2 μm to 0.5 μm, then ultrasonically cleaned in an ethanol solvent for 5 to 10 min, then ultrasonically cleaned in a propanol solvent for 15 to 20 min, then immersed in an acid solution for 3 to 5 min, washed with water, and dried with nitrogen.

[0009] By adopting the above technical scheme, mechanical polishing can improve the surface flatness and smoothness of the copper contact substrate, reduce the surface roughness, and help to make the coating particles 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. Excessive pickling will cause the copper contact surface to be rough or cause excessive corrosion.

[0010] Preferably, the acid solution consists of the following components in parts by weight: 3~8 parts of hydrochloric acid, 8~15 parts of citric acid, 2~5 parts of hydroxyethylidene diphosphonic acid, 1~3 parts of ethylenediaminetetraacetic acid, 0.5~1 parts of thiourea, 0.1~0.2 parts of polyvinylpyrrolidone, and 45~55 parts of water.

[0011] By adopting the above technical solution, the component can ensure effective cleaning while protecting the copper contact substrate. Citric acid and hydrochloric acid form a composite acid solution, which provides an acidic environment and improves the ability to remove oxides and impurities on the surface of the copper contact substrate; hydroxyethylidene diphosphonic acid and ethylenediaminetetraacetic acid have good chelating properties, which can prevent other metal ions from re-depositing on the copper contact surface during the cleaning process to cause secondary pollution; thiourea can slow down the corrosion rate of acid on copper; polyvinyl pyrrolidone can prevent dirt particles from re-aggregating on the copper surface and improve the cleaning ability.

[0012] Preferably, the background vacuum is 1×10 -4 ~1×10 -5 Pa.

[0013] Preferably, in step (2), the flow rate of argon gas is 120-150 Sccm, the voltage of the bias power supply used in glow cleaning is -500-600 V, the duty cycle is 50%-70%, and the glow cleaning time is 10-20 min.

[0014] Preferably, in step (3), the flow rate of argon gas is 30-80 Sccm.

[0015] Preferably, in step (3), the deposition process of the titanium nitride layer is as follows: the target material for depositing the titanium nitride layer is a titanium nitride target material with a purity of 99.999%, the DC power supply power of the titanium nitride target material is 100-200 W, the deposition gas 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.

[0016] By adopting the above technical solution, the high-purity titanium nitride target can ensure that the coating surface is flat and free of obvious defects and impurities; the titanium nitride film produced within this parameter range is smooth and dense.

[0017] Preferably, in step (4), the flow rate of argon gas is 150-180 sccm.

[0018] Preferably, in the step (4), the deposition process of the silver-iridium-cerium mixed metal layer is as follows: the target materials for depositing the silver-iridium-cerium mixed metal layer are silver target, iridium target and cerium target, the DC power supply power of the silver target is 150~300W, the DC power supply power of the iridium target is 50~150W, the DC power supply power of the cerium target is 50~80W, the deposition gas pressure is 0.5~1Pa, the voltage of the bias power supply is -50~-150V, and the deposition time is 60~80min.

[0019] Preferably, the ratio of the number of silver targets, iridium targets and cerium targets is 3:1:1.

[0020] By adopting the above technical solution, the conductivity advantage of silver can be fully utilized under this ratio, and a small amount of iridium and cerium can improve the hardness and oxidation resistance of the contacts to a certain extent.

[0021] Preferably, in 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%” mean “20% by weight” and “80% by weight”.

[0022] By adopting the above technical solution, annealing in this atmosphere can make the crystal structure of the silver-iridium-cerium film more complete, reduce defects and lattice distortion, and make the copper contact have better conductivity.

[0023] In summary, the beneficial effects of the present invention are: (1) The present invention improves the pretreatment process of copper contacts, and makes the surface of the copper contacts smooth and bright through mechanical polishing, solvent cleaning and pickling; and sequentially deposits a titanium nitride layer and a silver-iridium-cerium mixed metal layer on the surface of the copper contacts, thereby improving the hardness of the copper contacts; the present invention has fewer process steps and high efficiency, and the obtained coating has high hardness and good bonding strength; (2) The compounded acid solution of the present invention can quickly remove dirt on the surface of the copper contact without excessively corroding the copper contact, has high cleaning efficiency, and can provide a uniform substrate for subsequent magnetron sputtering coating; (3) The present invention deposits a titanium nitride layer on the surface of the copper contact, which can form a good bond with the copper contact and provide a transition layer for the subsequent deposition of the silver-iridium-cerium mixed metal layer. Silver can form a good bond with the titanium nitride layer, so that the transition effect of the titanium nitride layer between copper and silver improves the overall bonding strength, reduces the bonding defects and weak points at the copper-silver interface, and avoids the problems of delamination and falling off during long-term use; (4) The present invention introduces iridium and cerium into the silver-plated layer. The addition of cerium can refine the silver grains, produce a solid solution strengthening effect, and make the microstructure of the coating more uniform and dense. Iridium has a high hardness, which can improve the hardness of the silver-plated layer and enhance the wear resistance of the copper contacts, making it less likely to deform, wear, and other problems during frequent use. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the appearance of the copper contact prepared in Example 1 of the present invention; Figure 2 This is a SEM morphology image of the copper contact prepared in Example 1 of the present invention; Figure 3 This is a SEM morphology image of the copper contact prepared in Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is explained in detail below with reference to several representative embodiments of the present invention.

[0026] Unless otherwise specified, the materials, reagents, etc. used in the following examples and comparative examples can be obtained from commercial sources.

[0027] 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%.

[0028] Example 1 The acid solution of this embodiment is composed of the following components: 3g hydrochloric acid, 10g citric acid, 3g hydroxyethylidene diphosphonic acid, 2g ethylenediaminetetraacetic acid, 0.8g thiourea, 0.1g polyvinylpyrrolidone, 45g water.

[0029] The copper contact coating process based on the magnetron sputtering method of this embodiment has the following specific steps: (1) Pre-treating the surface of the copper contact substrate, mechanically polishing the surface of the copper contact substrate to a surface roughness Ra of 0.3 μm, and then washing the copper contact substrate in an ethanol solvent for 10 minutes under ultrasonic conditions, and then washing it in a propanol solvent for 18 minutes under ultrasonic conditions, and then soaking it in an acid solution for 3 minutes, taking it out and rinsing it with deionized water for 20 minutes, and drying it with nitrogen gas to obtain a pre-treated copper contact substrate; (2) The pretreated copper contact substrate is transferred into a vacuum furnace, and a titanium nitride target, three silver targets, an iridium target, and a cerium target are placed in the sputtering chamber, and the sputtering chamber is evacuated to a background vacuum of 1×10 -4 Pa, 130 Sccm of argon gas was introduced, the voltage of the bias power supply was set to -550 V, the duty cycle was set to 50%, and the glow cleaning time was set to 15 min, and the copper contact substrate after glow cleaning was obtained; (3) After the copper contact substrate is glow cleaned, the vacuum furnace is evacuated to a background vacuum of 1×10 -4 Pa, 30 sccm of argon gas was introduced, the gas pressure was adjusted to 0.8 Pa, the rotating speed of the rotating frame was 3 r / min, the power of the DC sputtering power supply of the titanium nitride target was controlled to be 150 W, the voltage of the bias power supply was -100 V, and a titanium nitride layer was deposited on the copper contact substrate after glow cleaning for 10 minutes to obtain a copper contact substrate with a titanium nitride layer deposited thereon; (4) After the titanium nitride layer is formed, stop depositing the titanium nitride target; evacuate the vacuum furnace to a background vacuum of 1×10 -4 Pa, introduce 150sccm of argon gas, adjust the gas pressure to 0.5Pa, the rotating speed of the turret to 3r / min, control the DC power supply power of the silver target to 150W, the DC power supply power of the iridium target to 100W, and the DC power supply power of the cerium target to 60W, deposit a silver-iridium-cerium mixed metal layer on the copper contact substrate deposited with the titanium nitride layer for 60min, and terminate the deposition to obtain a sample; (5) The sample was placed in a tubular furnace for annealing treatment. The annealing atmosphere was 20 wt % hydrogen and 80 wt % argon. The heating rate was 5 ° C / min, the annealing temperature was 400 ° C, and the annealing time was 3 h. After cooling to room temperature in the furnace, a copper contact was obtained. The surface of the copper contact was smooth and dense. The appearance diagram of the copper contact is shown in FIG. Figure 1 , SEM morphology of copper contacts is shown in Figure 2 ;from Figure 2 It can be seen that the film layer prepared in Example 1 is relatively smooth and flat, and almost no obvious particle structure can be seen, indicating that the atoms are evenly spread during the deposition process to form a smooth and dense surface morphology.

[0030] Example 2 The acid solution of this embodiment is composed of the following components: 5g hydrochloric acid, 12g citric acid, 2g hydroxyethylidene diphosphonic acid, 1g ethylenediaminetetraacetic acid, 0.6g thiourea, 0.2g polyvinylpyrrolidone, 55g water.

[0031] The copper contact coating process based on the magnetron sputtering method of this embodiment has the following specific steps: (1) Pretreating the surface of the copper contact substrate, mechanically polishing the surface of the copper contact substrate to a surface roughness Ra of 0.5 μm, and then washing the copper contact substrate in an ethanol solvent for 10 minutes under ultrasonic conditions, and then washing it in a propanol solvent for 20 minutes under ultrasonic conditions, and then soaking it in an acid solution for 3 minutes, taking it out and rinsing it with deionized water for 20 minutes, and drying it with nitrogen gas to obtain a pretreated copper contact substrate; (2) The pretreated copper contact substrate is transferred into a vacuum furnace, and a titanium nitride target, three silver targets, an iridium target, and a cerium target are placed in the sputtering chamber, and the sputtering chamber is evacuated to a background vacuum of 1×10 -4 Pa, 120 Sccm of argon gas was introduced, the voltage of the bias power supply was set to -600 V, the duty cycle was set to 70%, and the glow cleaning time was set to 20 min, and the copper contact substrate after glow cleaning was obtained; (3) After the copper contact substrate is glow cleaned, the vacuum furnace is evacuated to a background vacuum of 1×10 -4 Pa, 80 sccm of argon gas was introduced, the gas pressure was adjusted to 0.3 Pa, the rotating speed of the rotating frame was 3 r / min, the power of the DC sputtering power supply of the titanium nitride target was controlled to 100 W, the voltage of the bias power supply was -150 V, and a titanium nitride layer was deposited on the copper contact substrate after glow cleaning for 15 minutes to obtain a copper contact substrate with a titanium nitride layer deposited thereon; (4) After the titanium nitride layer is formed, stop depositing the titanium nitride target; evacuate the vacuum furnace to a background vacuum of 1×10 -4 Pa, introduce 150sccm of argon gas, adjust the gas pressure to 0.6Pa, the rotating speed of the turret to 3r / min, control the DC power supply power of the silver target to 300W, the DC power supply power of the iridium target to 150W, and the DC power supply power of the cerium target to 80W, deposit a silver-iridium-cerium mixed metal layer on the copper contact substrate deposited with the titanium nitride layer for 80min, and terminate the deposition to obtain a sample; (5) The sample was placed in a tubular furnace for annealing. The annealing atmosphere was 20 wt % hydrogen and 80 wt % argon. The heating rate was 5 ° C / min, the annealing temperature was 350 ° C, and the annealing time was 2 h. After cooling to room temperature in the furnace, a copper contact was obtained.

[0032] Example 3 The acid solution of this embodiment is composed of the following components: 3g hydrochloric acid, 8g citric acid, 5g hydroxyethylidene diphosphonic acid, 3g ethylenediaminetetraacetic acid, 0.5g thiourea, 0.2g polyvinylpyrrolidone, 50g water.

[0033] The copper contact coating process based on the magnetron sputtering method of this embodiment has the following specific steps: (1) Pretreating the surface of the copper contact substrate, mechanically polishing the surface of the copper contact substrate to a surface roughness Ra of 0.2 μm, and then cleaning the copper contact substrate in an ethanol solvent for 5 minutes under ultrasonic conditions, and then cleaning it in a propanol solvent for 15 minutes under ultrasonic conditions, and then soaking it in an acid solution for 4 minutes. After taking it out, rinse it with deionized water for 20 minutes, and blow dry it with nitrogen to obtain a pretreated copper contact substrate; (2) The pretreated copper contact substrate is transferred into a vacuum furnace, and a titanium nitride target, three silver targets, an iridium target, and a cerium target are placed in the sputtering chamber, and the sputtering chamber is evacuated to a background vacuum of 1×10 -5 Pa, 150 Sccm of argon gas was introduced, the voltage of the bias power supply was set to -500 V, the duty cycle was set to 60%, and the glow cleaning time was set to 15 min, and the copper contact substrate after glow cleaning was obtained; (3) After the copper contact substrate is glow cleaned, the vacuum furnace is evacuated to a background vacuum of 1×10 -5 Pa, introduce 50 sccm of argon gas, adjust the gas pressure to 0.6 Pa, the rotating speed of the turret to 3 r / min, control the power of the DC sputtering power supply of the titanium nitride target to 200 W, the voltage of the bias power supply to -50 V, and start to deposit a titanium nitride layer on the glow-cleaned copper contact substrate for 5 minutes to obtain a copper contact substrate with a titanium nitride layer deposited thereon; (4) After the titanium nitride layer is formed, stop depositing the titanium nitride target; evacuate the vacuum furnace to a background vacuum of 1×10 -5 Pa, introduce 180sccm of argon gas, adjust the gas pressure to 0.8Pa, the rotating speed of the turret to 3r / min, control the DC power supply power of the silver target to 250W, the DC power supply power of the iridium target to 80W, and the DC power supply power of the cerium target to 80W, deposit a silver-iridium-cerium mixed metal layer on the copper contact substrate deposited with a titanium nitride layer for 80 minutes, and terminate the deposition to obtain a sample; (5) The sample was placed in a tubular furnace for annealing. The annealing atmosphere was 20 wt % hydrogen and 80 wt % argon. The heating rate was 5 ° C / min, the annealing temperature was 550 ° C, and the annealing time was 4 h. After cooling to room temperature in the furnace, a copper contact was obtained.

[0034] Example 4 The acid solution of this embodiment is composed of the following components: 8g hydrochloric acid, 15g citric acid, 2g hydroxyethylidene diphosphonic acid, 1g ethylenediaminetetraacetic acid, 1g thiourea, 0.1g polyvinylpyrrolidone, 55g water.

[0035] The copper contact coating process based on the magnetron sputtering method of this embodiment has the following specific steps: (1) Pre-treating the surface of the copper contact substrate, mechanically polishing the surface of the copper contact substrate to a surface roughness Ra of 0.3 μm, and then cleaning the copper contact substrate in an ethanol solvent for 8 minutes under ultrasonic conditions, and then cleaning it in a propanol solvent for 15 minutes under ultrasonic conditions, and then soaking it in an acid solution for 5 minutes. After taking it out, rinse it with deionized water for 20 minutes, and blow dry it with nitrogen to obtain a pre-treated copper contact substrate; (2) The pretreated copper contact substrate is transferred into a vacuum furnace, and a titanium nitride target, three silver targets, an iridium target, and a cerium target are placed in the sputtering chamber, and the sputtering chamber is evacuated to a background vacuum of 1×10 -5 Pa, 135 Sccm of argon gas was introduced, the voltage of the bias power supply was set to -600 V, the duty cycle was set to 60%, and the glow cleaning time was set to 10 min, and the copper contact substrate after glow cleaning was obtained; (3) After the copper contact substrate is glow cleaned, the vacuum furnace is evacuated to a background vacuum of 1×10 -5 Pa, 50 sccm of argon gas was introduced, the gas pressure was adjusted to 1 Pa, the rotating speed of the rotating frame was 3 r / min, the power of the DC sputtering power supply of the titanium nitride target was controlled to 100 W, the voltage of the bias power supply was -100 V, and a titanium nitride layer was deposited on the copper contact substrate after glow cleaning for 20 minutes to obtain a copper contact substrate with a titanium nitride layer deposited; (4) After the titanium nitride layer is formed, stop depositing the titanium nitride target; evacuate the vacuum furnace to a background vacuum of 1×10 -5 Pa, introduce 180sccm of argon gas, adjust the gas pressure to 1Pa, the rotating speed of the turret to 3r / min, control the DC power supply power of the silver target to 200W, the DC power supply power of the iridium target to 120W, and the DC power supply power of the cerium target to 50W, deposit a silver-iridium-cerium mixed metal layer on the copper contact substrate deposited with the titanium nitride layer for 60min, and terminate the deposition to obtain a sample; (5) The sample was placed in a tubular furnace for annealing. The annealing atmosphere was 20 wt % hydrogen and 80 wt % argon. The heating rate was 5 ° C / min, the annealing temperature was 500 ° C, and the annealing time was 4 h. After cooling to room temperature in the furnace, a copper contact was obtained.

[0036] Example 5 The acid solution of this embodiment is composed of the following components: 7g hydrochloric acid, 8g citric acid, 4g hydroxyethylidene diphosphonic acid, 3g ethylenediaminetetraacetic acid, 1g thiourea, 0.2g polyvinylpyrrolidone, 50g water.

[0037] The copper contact coating process based on the magnetron sputtering method of this embodiment has the following specific steps: (1) Pre-treating the surface of the copper contact substrate, mechanically polishing the surface of the copper contact substrate to a surface roughness Ra of 0.5 μm, and then cleaning the copper contact substrate in an ethanol solvent for 5 minutes under ultrasonic conditions, and then cleaning it in a propanol solvent for 20 minutes under ultrasonic conditions, and then soaking it in an acid solution for 5 minutes. After taking it out, rinse it with deionized water for 20 minutes, and blow dry it with nitrogen to obtain a pre-treated copper contact substrate; (2) The pretreated copper contact substrate is transferred into a vacuum furnace, and a titanium nitride target, three silver targets, an iridium target, and a cerium target are placed in the sputtering chamber, and the sputtering chamber is evacuated to a background vacuum of 1×10 -5 Pa, 140 Sccm of argon gas was introduced, the voltage of the bias power supply was set to -500 V, the duty cycle was set to 70%, and the glow cleaning time was set to 20 min, and the copper contact substrate after glow cleaning was obtained; (3) After the copper contact substrate is glow cleaned, the vacuum furnace is evacuated to a background vacuum of 1×10 -5 Pa, introduce 60 sccm of argon gas, adjust the gas pressure to 0.5 Pa, the rotating speed of the turret 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 to deposit a titanium nitride layer on the glow-cleaned copper contact substrate for 20 minutes to obtain a copper contact substrate with a titanium nitride layer deposited thereon; (4) After the titanium nitride layer is formed, stop depositing the titanium nitride target; evacuate the vacuum furnace to a background vacuum of 1×10 -5 Pa, introduce 150sccm of argon gas, adjust the gas pressure to 0.8Pa, the rotating speed of the turret to 3r / min, control the DC power supply power of the silver target to 220W, the DC power supply power of the iridium target to 90W, and the DC power supply power of the cerium target to 70W, deposit a silver-iridium-cerium mixed metal layer on the copper contact substrate deposited with the titanium nitride layer for 70min, terminate the deposition, and obtain a sample; (5) The sample was placed in a tubular furnace for annealing. The annealing atmosphere was 20 wt % hydrogen and 80 wt % argon. The heating rate was 5 ° C / min, the annealing temperature was 450 ° C, and the annealing time was 3 h. After cooling to room temperature in the furnace, a copper contact was obtained.

[0038] Comparative Example 1 The difference from Example 1 is that the components of the acid solution are adjusted in this comparative example, as shown in Table 1, and the rest are the same as Example 1.

[0039] Table 1 Acid composition

[0040] Comparative Example 2 The difference from Example 1 is that the titanium oxide target is used to replace the titanium nitride target, and the rest is the same as Example 1.

[0041] Comparative Example 3 The difference from Example 1 is that the titanium target is used to replace the titanium nitride target, and 30 sccm of argon and 20 sccm of nitrogen are used to replace 30 sccm of argon. The rest is the same as Example 1. The SEM morphology of the copper contact prepared in Comparative Example 3 is shown in FIG. Figure 3 .

[0042] Comparative Example 4 The difference from Example 1 is that the titanium nitride layer is not deposited in this comparative example, and the rest is the same as Example 1.

[0043] Comparative Example 5 The difference from Example 1 is that in this comparative example, a silver metal layer is deposited on the titanium nitride layer of the copper contact substrate, and the rest is the same as Example 1.

[0044] Comparative Example 6 The difference from Example 1 is that in this comparative example, a silver-iridium mixed metal layer is deposited on the titanium nitride layer of the copper contact substrate, and the rest is the same as Example 1.

[0045] Comparative Example 7 The difference from Example 1 is that in this comparative example, a silver-cerium mixed metal layer is deposited on the titanium nitride layer of the copper contact substrate, and the rest is the same as Example 1.

[0046] Comparative Example 8 The difference from Example 1 is that this comparative example uses indium target material to replace iridium target material, and the rest is the same as Example 1.

[0047] Related performance tests The copper contacts prepared in Examples 1 to 5 and Comparative Examples 1 to 8 were subjected to relevant performance tests: Resistivity test: the resistivity of the copper contacts was calculated using the four-probe method; Adhesion test: each copper contact was placed in a high temperature and high humidity environment for 48 hours, a tape was attached to the surface of each copper contact and then the tape was removed to check for shedding; Hardness test: the nanohardness of the sample was tested using a nanoindenter, and each copper contact was measured 5 times to take the average value; The test results are shown in Table 2.

[0048] Table 2 Test results

[0049] By comparing Comparative Example 1 with Example 1, it can be seen that the components of the acid solution in Comparative Example 1 are changed, but the performance of the copper contact obtained is deteriorated, which shows that the components and dosage ratio of the acid solution in the present invention have been optimized.

[0050] From the comparison between Comparative Example 2 and Example 1, it can be seen that the resistivity of titanium oxide is relatively high. When used as a transition layer, it will increase the overall resistance of the contact to a certain extent; while when titanium nitride is used as a transition layer, it has little effect on the overall resistivity of the contact.

[0051] By comparing Comparative Example 3 with Example 1, it can be seen that Comparative Example 3 changes the deposition method of the titanium nitride film; Figure 3 It can be seen that the film layer prepared in Comparative Example 3 has no obvious defects, but exhibits a relatively rough texture and the presence of many tiny granular structures, indicating that atomic clusters aggregate during the deposition process, and the titanium nitride film deposited with metal titanium as a target in a nitrogen and argon atmosphere is uneven in quality and has a rough surface; the rough film surface and granular structure 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 force, resulting in reduced adhesion and hardness of the film layer. Therefore, the performance of the copper contact obtained is not as good as that obtained by directly depositing the titanium nitride target.

[0052] From the comparison between Comparative Example 4 and Example 1, it can be seen 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 strength.

[0053] By comparing Comparative Examples 5, 6 and 7 with Example 1, it can be seen that the combination of the three elements of silver, iridium and cerium makes the copper contact performance reach the best.

[0054] From the comparison between Comparative Example 8 and Example 1, it can be seen that the addition of indium has little effect on the resistivity, but the hardness of indium is lower than that of iridium, so the addition of indium has limited effect on the improvement of the hardness of the copper contact.

[0055] The above is 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 done by other technicians in this field without expending creative labor falls within the protection scope of the present invention.

Claims

1. A copper contact coating process based on magnetron sputtering method, characterized in that: The steps include: (1) Pre-treating the surface of the copper contact substrate, wherein the pre-treatment includes mechanical polishing, solvent cleaning and pickling to obtain a pre-treated copper contact substrate; (2) transferring the pretreated copper contact substrate into a vacuum furnace, evacuating the furnace to a background vacuum, introducing argon gas and adjusting the gas pressure, and performing glow cleaning to obtain a glow-cleaned copper contact substrate; (3) evacuating the gas to a background vacuum, introducing argon gas, and using magnetron sputtering to deposit a titanium nitride layer on the surface of the glow-cleaned copper contact substrate to obtain a copper contact substrate on which a titanium nitride layer is deposited; (4) evacuating the gas to the background vacuum, introducing argon gas, and using magnetron sputtering to deposit a silver-iridium-cerium mixed metal layer on the surface of the copper contact substrate on which the titanium nitride layer was deposited, and then completing the deposition to obtain a sample; (5) The sample is annealed to obtain copper contacts.

2. The copper contact coating process based on magnetron sputtering method according to claim 1, characterized in that: In the step (1), the surface of the copper contact substrate is mechanically polished to a surface roughness Ra of 0.2 μm to 0.5 μm, then ultrasonically cleaned in an ethanol solvent for 5 to 10 min, then ultrasonically cleaned in a propanol solvent for 15 to 20 min, then immersed in an acid solution for 3 to 5 min, washed with water, and dried with nitrogen.

3. The copper contact coating process based on magnetron sputtering method according to claim 2, characterized in that: The acid solution is composed of the following components in parts by mass: 3~8 parts of hydrochloric acid, 8~15 parts of citric acid, 2~5 parts of hydroxyethylidene diphosphonic acid, 1~3 parts of ethylenediaminetetraacetic acid, 0.5~1 parts of thiourea, 0.1~0.2 parts of polyvinylpyrrolidone, and 45~55 parts of water.

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

5. The copper contact coating process based on magnetron sputtering method according to claim 1, characterized in that: In the step (3), the flow rate of argon gas is 30-80 Sccm.

6. The copper contact coating process based on magnetron sputtering method according to claim 1, characterized in that: In the step (3), the deposition process of the titanium nitride layer is as follows: the target material for depositing the titanium nitride layer is a titanium nitride target material with a purity of 99.999%, the DC power supply power of the titanium nitride target material is 100-200W, the deposition gas pressure is 0.3-1Pa, the voltage of the bias power supply is -50--150V, and the deposition time is 5-20min.

7. The copper contact coating process based on magnetron sputtering method according to claim 1, characterized in that: In the step (4), the flow rate of argon gas is 150-180 sccm.

8. The copper contact coating process based on 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 as follows: the target materials for depositing the silver-iridium-cerium mixed metal layer are silver target, iridium target and cerium target, the DC power supply power of the silver target is 150-300W, the DC power supply power of the iridium target is 50-150W, and the DC power supply power of the cerium target is 50-80W; the deposition gas pressure is 0.5-1Pa, the voltage of the bias power supply is -50--150V, and the deposition time is 60-80min.

9. The copper contact coating process based on magnetron sputtering method according to claim 8, characterized in that: The number ratio of silver target, iridium target and cerium target is 3:1:

1.

10. The copper contact coating process based on 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 350-550° C., and the annealing time is 2-4 hours.

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