A method for high-speed deposition of aluminum oxide coating using ultra-high temperature liquid target high-power pulsed magnetron sputtering technology

Abstract

A method for high-speed deposition of aluminum oxide coatings using high-power pulsed magnetron sputtering technology on ultra-high temperature liquid target materials, which relates to a method for high-speed deposition of aluminum oxide coatings. The present invention aims to solve the problem of target poisoning in the existing sputtering deposition process of aluminum oxide coatings, which leads to a very low sputtering rate of the target material. Method: 1. Place the sputtering target material in the target seat, and adjust the gap between the target seat and the magnetron target cooling base; 2. Form a high-power pulsed magnetron sputtering discharge through a high-power pulsed magnetron power supply until the surface of the target material melts; 3. Introduce O2 gas and perform sputtering at high power and ultra-high temperature. The present invention is used for high-speed deposition of aluminum oxide coatings using high-power pulsed magnetron sputtering technology on ultra-high temperature liquid target materials.

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

[0003] However, for the sputtering deposition of aluminum oxide coatings, reactive oxygen gas must be introduced during the deposition process. As oxygen diffuses into the aluminum target surface, it will inevitably cover the target surface with an insulating aluminum oxide film in the sputtering runway area (i.e., target poisoning). Due to the high secondary electron emission coefficient of aluminum oxide, most of the sputtering current is electron current. 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, generally about an order of magnitude lower than that of pure metal sputtering. Therefore, the deposition rate of aluminum oxide is relatively 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 coatings and reduce the actual cost of using this technology has become a difficult problem that needs to be solved urgently in the industry. 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 using ultra-high temperature liquid target material and high-power pulsed magnetron sputtering technology.

[0005] A method for high-speed deposition of aluminum oxide coating using ultra-high temperature liquid target high-power pulsed magnetron sputtering technology 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] Second, the vacuum chamber is evacuated, and then Ar gas is introduced. A high-power pulsed magnetron sputtering discharge is generated by a high-power pulsed magnetron power supply to melt the target material and obtain a liquid target material;

[0008] 3. Keep the Ar gas flowing in, and at the same time, introduce 20 sccm to 100 sccm of O2 gas, at a power density of 5W / cm 2 ~20W / cm 2 Sputtering is performed 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.

[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 conventional HiPIMS technology, which prevents the deposition process from continuing during the pulse-off period. By evaporating the liquid target particles during the pulse-off period, it maintains a high particle flux and generates a high-density plasma with a high ionization rate when the discharge pulse is turned on. This combined effect effectively mitigates target poisoning, maintaining a high ionization rate while significantly increasing the deposition rate, achieving a deposition rate of 48.3nm / min for stoichiometric aluminum oxide (Al2O3).

[0011] Appendix

[0012] Figure 1 These are photos of the target material state changes in Example 1, where a is the target material not melted, b is the target material remaining liquid, and c is the target material runway area remaining liquid during the deposition of the aluminum oxide coating;

[0013] Figure 2 The discharge characteristics of solid and liquid targets 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 an SEM surface morphology of the aluminum oxide coating deposited at high speed using ultra-high temperature liquid target and high-power pulsed magnetron sputtering technology in Example 1;

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

[0016] Figure 5 This is the XPS spectrum of the aluminum oxide coating deposited at high speed using ultra-high temperature liquid target and 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 These are the optical transmittance curves of the SiO2 substrate coated with aluminum oxide prepared in Example 1 and the SiO2 substrate without the aluminum oxide coating. DETAILED DESCRIPTION

[0018] Specific embodiment 1: This embodiment 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] Second, the vacuum chamber is evacuated, and then Ar gas is introduced. A high-power pulsed magnetron sputtering discharge is generated by a high-power pulsed magnetron power supply to melt the target material and obtain a liquid target material;

[0021] 3. Keep the Ar gas flowing in, and at the same time, introduce 20 sccm to 100 sccm of O2 gas, at a power density of 5W / cm 2 ~20W / cm 2 Sputtering is performed 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.

[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 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 conventional HiPIMS technology, which prevents the deposition process from continuing during the pulse-off period. By evaporating the liquid target particles during the pulse-off period, it maintains a high particle flux and generates a high-density plasma with a high ionization rate when the discharge pulse is turned on. This combined effect effectively mitigates target poisoning, maintaining a high ionization rate while significantly increasing the deposition rate, achieving a deposition rate of 48.3nm / min for stoichiometric aluminum oxide (Al2O3).

[0024] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the sputtering target in step 1 is an Al target. Other aspects are the same as specific embodiment 1.

[0025] Specific embodiment 3: This embodiment differs from specific embodiment 1 or 2 in that the gap width in step 1 is 1 mm to 20 mm. Other aspects are the same as specific embodiment 1 or 2.

[0026] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that the substrate in step 1 is aluminum alloy, silicon negative electrode, 316L stainless steel or copper. Other aspects are 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 stage and suspended 50 mm to 300 mm above the sputtering target. Other steps are the same as specific embodiments 1 to 4.

[0028] Specific embodiment 6: This embodiment differs from the specific embodiments 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 in 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. Other steps are the same as specific embodiments 1 to 6.

[0030] Specific embodiment 8: This embodiment differs from Specific embodiments 1 to 7 in that, in step 2, a high-power pulsed magnetron sputtering discharge is generated by a high-power pulsed magnetron power supply 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 to melt the target surface. The discharge voltage amplitude is adjusted to maintain the discharge power at 0.6 kW to 5 kW until the target melts, thereby obtaining a liquid target. Other aspects are the same as Specific embodiments 1 to 7.

[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 0.6kW to 5kW until the target material is melted 80% to 100%. Other aspects are 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 flowing at a flow rate of 50 sccm to 100 sccm, while 20 sccm to 100 sccm of O2 gas is simultaneously introduced, and the pressure in the vacuum chamber is adjusted to 0.3 Pa to 1.0 Pa. Other aspects are the same as specific embodiments 1 to 9.

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

[0034] Example 1:

[0035] A method for high-speed deposition of aluminum oxide coating using ultra-high temperature liquid target high-power pulsed magnetron sputtering technology 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 5mm, place the substrate on the sample table and suspend it 150mm 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 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 100% melted to obtain a liquid target material;

[0039] 3. Keep Ar gas flowing in at a flow rate of 100 sccm and 50 sccm of O2 gas at the same time. Adjust the pressure in the vacuum chamber to 0.5 Pa and the power density to 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 to 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, the phase diagram shows that the temperature of the liquid phase zone of the liquid metal is within a range higher than the melting point of the metal, so the specific temperature value during sputtering cannot be accurately determined.

[0041] Comparative Experiment: This comparative experiment differs from Example 1 in that, in step 1, the target holder is adjusted to fit tightly against the magnetron target cooling base, step 2 is omitted, and in step 3, a solid target is used for sputtering, and the temperature limit is omitted. Other aspects are the same as Example 1.

[0042] Figure 1 The target material state changes in Example 1 are shown in Figures a and b. The target material remains liquid. The target material racetrack area remains liquid during the deposition of the aluminum oxide coating. In the initial stage of discharge, the target material is solid. 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 As shown in Figure b. When depositing the aluminum oxide coating, the target surface turns 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, the content of target metal particles in the plasma is relatively small, so 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 Figure 2. Figure 2 As shown in b.

[0044] Figure 3 This is an SEM surface morphology of the aluminum oxide coating deposited at high speed using ultra-high temperature liquid target and high-power pulsed magnetron sputtering technology in Example 1; Figure 4 This is an SEM cross-sectional morphology of the aluminum oxide coating deposited at high speed using ultra-high temperature liquid target and high-power pulsed magnetron sputtering technology in Example 1; Figure 5 This is the XPS spectrum of the aluminum oxide coating deposited at high speed using ultra-high temperature liquid target and 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 These are the optical transmittance curves of the SiO2 substrate coated with an aluminum oxide coating and the SiO2 substrate without a 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 gases 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, indicating excellent optical properties of the coating.

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 50mm to 300mm above the sputtering target; The gap width is 1mm to 20mm; 2. The vacuum chamber is evacuated, and then Ar gas is introduced. Under the conditions of a discharge voltage amplitude of 0.1kV to 2.0kV, a discharge power of 0.6kW to 5kW, a frequency of 1kHz to 10kHz, and a pulse width of 10μs to 500μs, a high-power pulse magnetron sputtering discharge is formed by a high-power pulse magnetron power supply to melt the surface of the target material. The discharge voltage amplitude is adjusted to maintain the discharge power at 0.6kW to 5kW until the target material is melted to obtain a liquid target material.

3. Keep Ar gas flowing and introduce 50sccm of O2 gas at the same time. 2 Sputtering is performed 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.

2. 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 The sputtering target material described in step 1 is an Al target.

3. 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 The substrate described in step 1 is aluminum alloy, silicon negative electrode, 316L stainless steel or copper.

4. 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, the vacuum chamber is evacuated to 1×10 -2 Below Pa.

5. 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.

6. 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 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%.

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 3, Ar gas is kept flowing in at a flow rate of 50 sccm to 100 sccm, while 20 sccm to 100 sccm of O2 gas is introduced, and the pressure in the vacuum chamber is adjusted to 0.3 Pa to 1.0 Pa.

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