Method for depositing aluminum oxide coating at high speed through ultrahigh-temperature liquid target material high-power pulse magnetron sputtering technology

Abstract

The invention discloses a method for depositing an aluminum oxide coating at a high speed by a high-power pulse magnetron sputtering technology of an ultrahigh-temperature liquid target material, and relates to a method for depositing an aluminum oxide coating at a high speed. The invention aims to solve the problem that the sputtering rate of a target material is very low due to a target poisoning phenomenon in the existing aluminum oxide coating sputtering deposition process. The method comprises the following steps: 1, putting a sputtering target material into a target seat, and adjusting a gap between the target seat and a magnetron target cooling base; 2, forming high-power pulse magnetron sputtering discharge through a high-power pulse magnetron power supply until the surface of the target material is molten; and 3, O2 gas is introduced, and sputtering is carried out at high power and ultra-high temperature. The method is used for high-speed deposition of the aluminum oxide coating through the ultrahigh-temperature liquid target high-power pulse magnetron sputtering technology.

Description

Technical Field

[0001] The invention relates to a method for high-speed deposition of aluminum oxide coating. Background Art

[0002] Alumina (Al2O3) coatings are widely used in various insulating materials, wear-resistant coatings, catalytic materials and optical observation windows in industry due to their good insulation, chemical stability, high hardness and high optical transmittance. At present, plasma spraying technology is often used in industry to prepare aluminum oxide coatings, mainly because the deposition rate of plasma spraying is high, but the quality of the prepared coatings is poor, and there are a large number of pores and defects in the coatings. Therefore, the coating thickness needs to be as high as hundreds of microns to meet the application requirements, which greatly increases the preparation cost of the coating. Compared with plasma spraying technology, magnetron sputtering technology, especially reactive high-power pulsed magnetron sputtering technology, produces coatings of higher quality, and only 5 to 10 microns are needed to meet the application requirements. Therefore, this technology has received more and more attention.

[0003] However, for the sputtering deposition of aluminum oxide coating, reactive gas oxygen must be introduced during the deposition process, and oxygen diffuses to the surface of the aluminum target, which will inevitably cover the target surface sputtering track area with an insulating aluminum oxide film (i.e., target poisoning phenomenon). Since the secondary electron emission coefficient of aluminum oxide is high, most of the sputtering current is electron current, and the main energy of sputtering is used to generate secondary electrons rather than metal particles, resulting in a lower sputtering rate of the target material, which is generally about an order of magnitude lower than that of pure metal sputtering. Therefore, the deposition rate of aluminum oxide is low, generally only 0.1nm / min to 5nm / min. Therefore, how to improve the deposition rate of magnetron sputtering technology in the preparation process of aluminum oxide coating and reduce the actual use cost of this technology has become a problem that the industry urgently needs to solve. Summary of the invention

[0004] The present invention aims to solve the problem of target poisoning in the existing sputtering deposition process of aluminum oxide coating, which leads to a very low sputtering rate of the target material, and further provides a method for high-speed deposition of aluminum oxide coating by ultra-high temperature liquid target material high-power pulsed magnetron sputtering technology.

[0005] A method for high-speed deposition of aluminum oxide coating using ultra-high temperature liquid target material high-power pulsed magnetron sputtering technology, which is carried out in the following steps:

[0006] 1. Place the sputtering target in the target holder, adjust the gap between the target holder and the magnetron target cooling base, place the substrate on the sample table and suspend it directly above the sputtering target;

[0007] 2. Evacuate the vacuum chamber, then introduce Ar gas, and use a high-power pulsed magnetron power supply to form a high-power pulsed magnetron sputtering discharge to melt the target material to obtain a liquid target material;

[0008] 3. Keep Ar gas flowing, and at the same time, introduce 20sccm~100sccm of O2 gas, at a power density of 5W / cm 2 ~20W / cm 2 The sputtering is carried out under the conditions of a frequency of 1kHz to 10kHz, a pulse width of 10μs to 500μs and a liquid target temperature of 1500K to 3500K, that is, a method for high-speed deposition of an aluminum oxide coating using ultra-high temperature liquid target high-power pulsed magnetron sputtering technology is completed.

[0009] The beneficial effects of the present invention are:

[0010] The present invention proposes a method for high-speed deposition of high-quality alumina coatings through ultra-high temperature liquid targets. This method combines the advantages of liquid target sputtering and high-power pulsed magnetron sputtering (HiPIMS), namely, liquid target HiPIMS technology. Compared with conventional liquid target sputtering deposition methods, the temperature of the liquid target in the present invention is far higher than its melting point. Even in the pulse-off stage, the temperature of the liquid target surface is still maintained at a high level, so that the evaporation process of the target particles can continue. The high particle flux in the runway area of ​​the target surface is maintained, and a strong gas rarefaction effect is formed, which effectively blocks the diffusion of active gas oxygen to the sputtering runway area and avoids the formation of insulating Al2O3 on the target surface. When the pulse is turned on, a large number of metal particles are ionized at the same time by high-power discharge and high-speed sputtering of the target, which significantly increases the density of metal ions in the plasma in the sputtering area, and effectively improves the quality of the coating through the bombardment effect of the incident ions. This method overcomes the limitation of traditional HiPIMS technology that the deposition process cannot be sustained during the pulse off period. It maintains a high particle flux during the pulse off period by evaporating the liquid target particles, and produces a high-density plasma and high ionization rate when the discharge pulse is turned on. This combined effect effectively alleviates the target poisoning phenomenon, not only maintaining a high ionization rate, but also significantly improving the deposition rate, so that the deposition rate of stoichiometric aluminum oxide (Al2O3) reaches 48.3nm / min.

[0011] Attached Notes

[0012] Figure 1 The photographs of the target material state changes in Example 1, a is that the target material is not melted, b is that the target material remains in a liquid state, and c is that the target material runway area remains in a liquid state when the aluminum oxide coating is deposited;

[0013] Figure 2 The discharge characteristics of solid and liquid target materials are compared in Example 1 and the comparative experiment. a is the sputtering ion flow of the solid target in the comparative experiment, and b is the sputtering ion flow of the liquid target in Example 1;

[0014] Figure 3This is a SEM surface morphology of the aluminum oxide coating deposited at high speed using ultra-high temperature liquid target high-power pulsed magnetron sputtering technology in Example 1;

[0015] Figure 4 This is a SEM cross-sectional morphology of the aluminum oxide coating deposited at high speed using ultra-high temperature liquid target high-power pulsed magnetron sputtering technology in Example 1;

[0016] Figure 5 This is the XPS spectrum of the aluminum oxide coating deposited at a high speed by the ultra-high temperature liquid target high-power pulsed magnetron sputtering technology in Example 1, a is the total spectrum, b is the O spectrum, and c is the Al spectrum;

[0017] Figure 6 The optical transmittance curves of the SiO2 substrate coated with aluminum oxide coating prepared in Example 1 and the SiO2 substrate without deposition coating. DETAILED DESCRIPTION

[0018] Specific implementation method 1: This implementation method is a method for high-speed deposition of aluminum oxide coating using ultra-high temperature liquid target material high-power pulsed magnetron sputtering technology, which is carried out in the following steps:

[0019] 1. Place the sputtering target in the target holder, adjust the gap between the target holder and the magnetron target cooling base, place the substrate on the sample table and suspend it directly above the sputtering target;

[0020] 2. Evacuate the vacuum chamber, then introduce Ar gas, and use a high-power pulsed magnetron power supply to form a high-power pulsed magnetron sputtering discharge to melt the target material to obtain a liquid target material;

[0021] 3. Keep Ar gas flowing, and at the same time, introduce 20sccm~100sccm of O2 gas, at a power density of 5W / cm 2 ~20W / cm 2 The sputtering is carried out under the conditions of a frequency of 1kHz to 10kHz, a pulse width of 10μs to 500μs and a liquid target temperature of 1500K to 3500K, that is, a method for high-speed deposition of an aluminum oxide coating using ultra-high temperature liquid target high-power pulsed magnetron sputtering technology is completed.

[0022] The beneficial effects of this embodiment are:

[0023] This embodiment proposes a method for high-speed deposition of high-quality alumina coatings through ultra-high temperature liquid targets. This method combines the advantages of liquid target sputtering and high-power pulsed magnetron sputtering (HiPIMS), namely liquid target HiPIMS technology. Compared with conventional liquid target sputtering deposition methods, the temperature of the liquid target in this embodiment is far higher than its melting point. Even in the pulse off stage, the temperature of the liquid target surface remains at a high level, so that the evaporation process of the target particles can continue. The high particle flux in the runway area of ​​the target surface is maintained, and a strong gas rarefaction effect is formed, which effectively blocks the diffusion of active gas oxygen to the sputtering runway area and avoids the formation of insulating Al2O3 on the target surface. When the pulse is turned on, a large number of metal particles are ionized at the same time by high-power discharge and high-speed sputtering of the target, which significantly increases the density of metal ions in the plasma in the sputtering area, and effectively improves the quality of the coating through the bombardment effect of the incident ions. This method overcomes the limitation of traditional HiPIMS technology that the deposition process cannot be sustained during the pulse off period. It maintains a high particle flux during the pulse off period by evaporating the liquid target particles, and produces a high-density plasma and high ionization rate when the discharge pulse is turned on. This combined effect effectively alleviates the target poisoning phenomenon, not only maintaining a high ionization rate, but also significantly improving the deposition rate, so that the deposition rate of stoichiometric aluminum oxide (Al2O3) reaches 48.3nm / min.

[0024] Specific implementation method 2: This implementation method is different from specific implementation method 1 in that the sputtering target material in step 1 is an Al target. The rest is the same as specific implementation method 1.

[0025] Specific implementation method 3: This implementation method is different from specific implementation method 1 or 2 in that the gap width in step 1 is 1 mm to 20 mm. The rest is the same as specific implementation method 1 or 2.

[0026] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that the substrate described in step 1 is aluminum alloy, silicon negative electrode, 316L stainless steel or copper. The rest is the same as specific embodiments 1 to 3.

[0027] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that: in step 1, the substrate is placed on the sample table and suspended 50 mm to 300 mm above the sputtering target. The rest is the same as specific embodiments 1 to 4.

[0028] Specific implementation method 6: This implementation method is different from the specific implementation methods 1 to 5 in that: in step 2, the vacuum chamber is evacuated to 1×10 -2 Pa or less. Other aspects are the same as those of the first to fifth embodiments.

[0029] Specific embodiment 7: This embodiment differs from specific embodiments 1 to 6 in that: in step 2, 10 sccm to 200 sccm of Ar gas is introduced, and the pressure in the vacuum chamber is adjusted to 0.1 Pa to 10 Pa. The rest is the same as specific embodiments 1 to 6.

[0030] Specific embodiment eight: This embodiment differs from specific embodiments one to seven in that: in step two, under the conditions of a discharge voltage amplitude of 0.1 kV to 2.0 kV, a discharge power of 0.6 kW to 5 kW, a frequency of 1 kHz to 10 kHz, and a pulse width of 10 μs to 500 μs, a high-power pulsed magnetron sputtering discharge is formed by a high-power pulsed magnetron power supply to melt the surface of the target material, and the discharge voltage amplitude is adjusted to maintain the discharge power of 0.6 kW to 5 kW until the target material is melted to obtain a liquid target material. The rest is the same as specific embodiments one to seven.

[0031] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that the discharge voltage amplitude is adjusted to maintain the discharge power at 0.6 kW to 5 kW until the target material is melted by 80% to 100%. The rest is the same as specific embodiments 1 to 8.

[0032] Specific embodiment 10: This embodiment differs from specific embodiments 1 to 9 in that: in step 3, Ar gas is kept introduced with a flow rate of 50 sccm to 100 sccm, 20 sccm to 100 sccm of O2 gas is introduced at the same time, and the pressure in the vacuum chamber is adjusted to 0.3 Pa to 1.0 Pa. The rest is the same as specific embodiments 1 to 9.

[0033] The following examples are used to verify the beneficial effects of the present invention:

[0034] Embodiment 1:

[0035] A method for high-speed deposition of aluminum oxide coating using ultra-high temperature liquid target material high-power pulsed magnetron sputtering technology, which is carried out in the following steps:

[0036] 1. Place the sputtering target in the target holder, adjust the gap between the target holder and the magnetron target cooling base to 5 mm, place the substrate on the sample table and suspend it 150 mm above the sputtering target;

[0037] The sputtering target is an Al target; the substrate is a SiO2 substrate;

[0038] 2. Evacuate the vacuum chamber to 5×10 -3Pa, then 100 sccm of Ar gas is introduced, the gas pressure in the vacuum chamber is adjusted to 0.5 Pa, and then a high-power pulsed magnetron sputtering discharge is formed by a high-power pulsed magnetron power supply under the conditions of a discharge voltage amplitude of 1.0 kV, a discharge power of 2 kW, a frequency of 1 kHz and a pulse width of 300 μs to melt the surface of the target material, and the discharge voltage amplitude is adjusted to maintain the discharge power at 1.5 kW until the target material is melted 100%, thereby obtaining a liquid target material;

[0039] 3. Keep Ar gas flowing in at a flow rate of 100 sccm, and at the same time, flow in 50 sccm of O2 gas, adjust the pressure in the vacuum chamber to 0.5 Pa, and at a power density of 5 W / cm 2 Sputtering was carried out for 30 minutes under the conditions of a frequency of 1 kHz, a pulse width of 300 μs and a liquid target temperature of 1500K~3500K to obtain an alumina coating deposited at a high speed by ultra-high temperature liquid target high-power pulsed magnetron sputtering technology, that is, a SiO2 substrate covered with an alumina coating.

[0040] In this embodiment, since the sputtering zone of the liquid target material always remains in liquid state, it can be seen from the phase diagram that the temperature of the liquid phase zone of the liquid metal is a range of values ​​higher than the melting point of the metal, so the specific temperature value during sputtering cannot be accurately determined.

[0041] Comparative experiment: The difference between this comparative experiment and Example 1 is that in step 1, the target holder is adjusted to fit closely with the magnetron target cooling base, step 2 is omitted, and step 3 uses solid target material for sputtering, and temperature limitation is omitted. The rest is the same as Example 1.

[0042] Figure 1 The target material state change photos in Example 1, a is the target material is not melted, b is the target material remains liquid, c is the target material racetrack area remains liquid when the aluminum oxide coating is deposited; in the initial stage of discharge, the target material is solid, such as Figure 1 As shown in a, as the sputtering energy continues to accumulate, the target surface gradually melts and maintains a liquid state, as shown in Figure 1 When the aluminum oxide coating is deposited, the target surface is transformed into a solid state except for the sputtering runway area due to the introduction of oxygen. However, due to the extremely high density of metal particles in the sputtering plasma in the runway area, the diffusion of oxygen to the runway area is effectively blocked, effectively alleviating the target poisoning phenomenon, as shown in Figure 2. Figure 1 As shown in c.

[0043] Figure 2The discharge characteristics of solid and liquid target materials are compared in Example 1 and the comparative experiment. a is the solid target sputtering ion flow in the comparative experiment, and b is the liquid target sputtering ion flow in Example 1. The substrate ion flow is collected by collecting the ion current reaching the substrate position, which can characterize the number of ions and energy received by the substrate during the coating deposition process. Therefore, the substrate ion flow is proportional to the coating deposition rate. When using traditional solid target materials for sputtering deposition of aluminum oxide coatings, due to the low energy efficiency and the relatively small content of target metal particles in the plasma, the detected substrate ion flow is also relatively low. Figure 2 Compared with solid targets, due to the evaporation and large-scale ionization of liquid metal ions, the content of metal particles in the discharge plasma is higher than that of solid targets, and the ion flow increases by 2 to 3 times, as shown in Fig. Figure 2 As shown in b.

[0044] Figure 3 This is a SEM surface morphology of the aluminum oxide coating deposited at high speed using ultra-high temperature liquid target high-power pulsed magnetron sputtering technology in Example 1; Figure 4 This is a SEM cross-sectional morphology of the aluminum oxide coating deposited at high speed using ultra-high temperature liquid target high-power pulsed magnetron sputtering technology in Example 1; Figure 5 This is the XPS spectrum of the aluminum oxide coating deposited at a high speed by the ultra-high temperature liquid target high-power pulsed magnetron sputtering technology in Example 1, a is the total spectrum, b is the O spectrum, and c is the Al spectrum; Figure 6 Optical transmittance curves of the SiO2 substrate coated with aluminum oxide coating and the SiO2 substrate without deposition coating prepared in Example 1; since liquid target magnetron sputtering can maintain a higher plasma density, provide a higher substrate ion flow, and effectively block the diffusion of active gas to the surface, the deposition rate and deposition quality of the aluminum oxide coating are improved. Figures 3 to 6 Given at 5W / cm 2 The microstructure characterization results of the aluminum oxide coating deposited for 30 minutes under discharge power. Figures 3 to 6 The test results show that the alumina coating obtained by liquid target magnetron sputtering deposition is smooth and dense, with a coating thickness of 1.45μm, a deposition rate of 48.3nm / min, a chemical composition close to the ideal stoichiometric ratio of 1.5, and a full-band optical transmittance of the coating close to that of the SiO2 substrate, and the coating has excellent optical properties.

Claims

1. A method for high-speed deposition of aluminum oxide coating using ultra-high temperature liquid target high-power pulsed magnetron sputtering technology, characterized in that It is carried out in the following steps:

1. Place the sputtering target in the target holder, adjust the gap between the target holder and the magnetron target cooling base, place the substrate on the sample table and suspend it directly above the sputtering target; 2. Evacuate the vacuum chamber, then introduce Ar gas, and use a high-power pulsed magnetron power supply to form a high-power pulsed magnetron sputtering discharge to melt the target material to obtain a liquid target material; 3. Keep Ar gas flowing, and at the same time, introduce 20sccm~100sccm of O2 gas, at a power density of 5W / cm 2 ~20W / cm 2 The sputtering is carried out under the conditions of a frequency of 1kHz to 10kHz, a pulse width of 10μs to 500μs and a liquid target temperature of 1500K to 3500K, that is, a method for high-speed deposition of an aluminum oxide coating using ultra-high temperature liquid target high-power pulsed magnetron sputtering technology is completed.

2. The method for high-speed deposition of aluminum oxide coating by ultra-high temperature liquid target high-power pulsed magnetron sputtering technology according to claim 1 is characterized in that The sputtering target material described in step 1 is an Al target.

3. The method for high-speed deposition of aluminum oxide coating by ultra-high temperature liquid target high-power pulsed magnetron sputtering technology according to claim 1 is characterized in that The gap width described in step 1 is 1 mm to 20 mm.

4. The method for high-speed deposition of aluminum oxide coating by ultra-high temperature liquid target high-power pulsed magnetron sputtering technology according to claim 1 is characterized in that The substrate described in step 1 is aluminum alloy, silicon negative electrode, 316L stainless steel or copper.

5. The method for high-speed deposition of aluminum oxide coating by ultra-high temperature liquid target high-power pulsed magnetron sputtering technology according to claim 1 is characterized in that In step 1, the substrate is placed on the sample stage and suspended 50 mm to 300 mm above the sputtering target.

6. The method for high-speed deposition of aluminum oxide coating by ultra-high temperature liquid target high-power pulsed magnetron sputtering technology according to claim 1 is characterized in that In step 2, the vacuum chamber is evacuated to 1×10 -2 Below Pa.

7. The method for high-speed deposition of aluminum oxide coating using ultra-high temperature liquid target high-power pulsed magnetron sputtering technology according to claim 1 is characterized in that In step 2, 10 sccm to 200 sccm of Ar gas is introduced, and the pressure in the vacuum chamber is adjusted to 0.1 Pa to 10 Pa.

8. The method for high-speed deposition of aluminum oxide coating using ultra-high temperature liquid target high-power pulsed magnetron sputtering technology according to claim 1 is characterized in that In step 2, under the conditions of a discharge voltage amplitude of 0.1 kV to 2.0 kV, a discharge power of 0.6 kW to 5 kW, a frequency of 1 kHz to 10 kHz and a pulse width of 10 μs to 500 μs, a high-power pulsed magnetron sputtering discharge is formed by a high-power pulsed magnetron power supply to melt the surface of the target material, and the discharge voltage amplitude is adjusted to maintain the discharge power at 0.6 kW to 5 kW until the target material is melted to obtain a liquid target material.

9. The method for high-speed deposition of aluminum oxide coating using ultra-high temperature liquid target high-power pulsed magnetron sputtering technology according to claim 8, characterized in that The discharge voltage amplitude is adjusted to maintain the discharge power at 0.6 kW to 5 kW until the target material is melted by 80% to 100%.

10. The method for high-speed deposition of aluminum oxide coating using ultra-high temperature liquid target high-power pulsed magnetron sputtering technology according to claim 1, characterized in that In step 3, Ar gas is kept flowing in, and the Ar gas flow rate is 50 sccm to 100 sccm, and 20 sccm to 100 sccm of O2 gas is introduced at the same time, and the pressure in the vacuum chamber is adjusted to 0.3 Pa to 1.0 Pa.

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