Laser additive manufacturing method for high-performance pure silver sputtering target material

Abstract

The invention discloses a laser additive manufacturing method of a high-performance pure silver sputtering target material. The laser additive manufacturing method comprises the following steps: taking spherical gas atomization silver powder as a raw material; a PBF-LB / M system is used, laser additive manufacturing is conducted on the spherical gas atomization silver powder under inert atmosphere protection, the technological parameters include that the laser power is 400 W, the scanning speed v ranges from 900 mm / s to 1000 mm / s, the scanning interval h ranges from 0.09 mm to 0.13 mm, the powder layer thickness is 30 microns, meanwhile, the technological index that h / v = (0.9-1.3) * 10 <-4 > is met, and the pure silver sputtering target material is obtained. Based on the PBF-LB / M technology, the purposes of grain refinement, density improvement and surface performance improvement of the pure silver sputtering target material are achieved through parameter optimization and structure regulation and control, the film forming rate and uniformity in the thin film deposition process are improved, the service life of the target material is prolonged, and the method can be applied to the fields of OLED, capacitors, photoelectric films and other high-end electronic devices.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology, specifically relating to a laser additive manufacturing method for a high-performance pure silver sputtering target. Background Technology

[0002] Silver (Ag), as a precious metal, is widely used in the sputtering fabrication of thin films for high-end electronic devices, such as transparent electrodes, reflective films, and radiation-resistant layers, due to its excellent electrical conductivity, thermal conductivity, and optical reflectivity. The demand for Ag is further increasing, especially with the rapid development of artificial intelligence (AI). The performance of the sputtering target directly affects the uniformity, conductivity, and lifespan of the thin film; therefore, there is an urgent need to develop a high-density and high-stability silver sputtering target.

[0003] Currently, commercial silver sputtering targets mainly rely on multi-step machining processes such as ingot casting, forging, rolling, and annealing, which have problems such as complex processes, uneven grain size, long cycle time, and large waste of precious metals. In addition, the grain size of traditional targets is generally tens of micrometers, with few grain boundaries, which is not conducive to efficient and stable sputtering. In the existing technology, the production process of pure silver targets still has the following defects: (1) The heat treatment process easily makes the pure silver target grains coarse and has few grain boundaries, resulting in unstable initial sputtering; (2) Non-uniform etch pits (race tracks) are prone to appear on the target surface, reducing the life of the target; (3) The processing cycle is long, the forming process wastes materials, and it is difficult to meet the needs of small-batch customized preparation.

[0004] Patent document CN118926549A discloses an additive manufacturing and defect optimization method for pure silver blocks, comprising: polishing and cleaning a substrate to ensure the cleanliness of selected additive areas on the substrate surface; preparing pure silver powder using gas atomization powder preparation; using an infrared laser beam under argon protection to perform laser powder bed fusion treatment on the Ag powder in selected areas of the substrate according to a set sample size; controlling and reducing internal defects of the sample by adjusting process parameters to obtain a pure silver block; performing metallographic sample preparation on the pure silver block; and analyzing surface defects of the pure silver block using Image-J software. The method uses L-PBF to print pure silver material, improving the density of the printed product and reducing its defect content by optimizing and adjusting laser power, laser scanning speed, and scanning channel spacing. Simultaneously, the silver target is prepared using gas atomization powder preparation, reducing processing waste and improving target quality while lowering target production costs. However, the above technical solutions focus on solving defects such as low density and poor fusion of pure silver in the preparation of PBF-LB / M, and emphasize improving the forming quality by optimizing scanning speed and spacing under low energy consumption conditions. They do not involve the special performance control and application verification of pure silver sputtering targets, nor do they involve the optimization of indicators such as the microstructure and electrical properties of pure silver sputtering targets. Summary of the Invention

[0005] The purpose of this invention is to propose a laser additive manufacturing method for high-performance pure silver sputtering targets. Based on the laser powder bed melting (PBF-LB / M) process, through parameter optimization and structural control, the method achieves grain refinement, density improvement, and surface performance enhancement of the pure silver sputtering target, thereby improving the film deposition rate, uniformity, and target lifespan during the thin film deposition process. This solves the problems of coarse grains, uneven sputtering, film quality fluctuations, and serious processing waste in the traditional pure silver target preparation process.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A laser additive manufacturing method for a high-performance pure silver sputtering target includes the following steps:

[0008] (1) Use spherical gas-atomized silver powder as raw material;

[0009] (2) The spherical gas-atomized silver powder was laser-additively manufactured using a PBF-LB / M system under an inert atmosphere. The process parameters for laser additive manufacturing included: laser power (P) of 400W, scanning speed (v) of 900–1000 mm / s, scanning spacing (h) of 0.09–0.13 mm, and powder layer thickness (t) of 30 μm, while simultaneously satisfying h / v = (0.9–1.3) × 10⁻⁶. -4 By controlling the process parameters, pure silver sputtering targets were obtained.

[0010] Preferably, in step (1), the spherical atomized silver powder has a particle size of 20-63 μm and a purity of not less than 99.99%.

[0011] Preferably, in step (2), the wavelength of the PBF-LB / M system is 1070nm.

[0012] Preferably, in step (2), the inert gas is argon.

[0013] Preferably, in step (2), the relative density of the pure silver sputtering target is greater than 99.5%.

[0014] Preferably, in step (2), the grain size of the pure silver sputtering target is less than 4 μm.

[0015] Preferably, in step (2), the surface roughness of the pure silver sputtering target is less than 12 μm.

[0016] Preferably, in step (2), the hardness of the pure silver sputtering target is 52.4 HV.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] I. This invention improves the density and grain uniformity of pure silver targets by adjusting the scanning speed-to-pitch ratio (h / v) instead of the traditional Ev parameter, achieving multiple objectives such as grain refinement, increased density, and improved surface properties. When the h / v value is close to 10... -4 At that time, pure silver sputtering targets had high density, with a relative density greater than 99.5%, grain size less than 4μm, surface roughness less than 12μm, and hardness increased by more than 40%. The superior sputtering rate and film performance were verified. The superior film formation rate and film performance were verified through magnetron sputtering experiments. The film formation rate could be stably reached 31.8nm / min, the sputtering runway area was uniform, the groove depth was 202.1μm, and there were no obvious defects. This provides a technical approach for the industrial customization of precious metal sputtering targets.

[0019] Second, this invention shifts from "additive manufacturing of bulk materials" to the preparation and performance integration of "functional sputtering targets". For the first time, it realizes a closed-loop process chain of parameter control, structural optimization and sputtering performance improvement. The integrated forming of the target material is completed with less than 500g of silver powder, which significantly saves materials and costs. The pure silver sputtering target material has high density and stability and can be applied to high-end electronic devices such as OLEDs, capacitors and optoelectronic films. Attached Figure Description

[0020] Figure 1 The images shown are photographs of the pure silver sputtering target at different stages in the embodiment; a: CAD model; b: before sputtering; c: after sputtering.

[0021] Figure 2 The following are verification results of the factors affecting the relative density of the pure silver sputtering target prepared in the examples: (a) Effect of energy input density on the relative density of Ag, where black dots represent v = 400, 500, 600, and 700 mm / s; red dots represent v values ​​of 500 mm / s, 600 mm / s, and 700 mm / s; blue dots represent h = 0.09, 0.11, 0.13, 0.15, and 0.18 mm; purple dots represent h = 0.09, 0.11, and 0.13 mm; and green dots represent h = 0.09, 0.11, and 0.13 mm; (b) Effect of hatch spacing / scanning speed (h / v) on relative density.

[0022] Figure 3 The surface roughness test results of the pure silver sputtering target prepared by the PBF-LB / M process in the examples are as follows: (a) P = 400 W, v = 1000 mm / min, h = 0.09 mm; (b) P = 400 W, v = 700 mm / min, h = 0.2 mm.

[0023] Figure 4 The results show the surface hardness test results of pure silver sputtering targets prepared by conventional and laser additive manufacturing processes in the examples.

[0024] Figure 5 The images shown are SEM and AFM images of the silver film at different sputtering times in the examples; a: 5 min, b: 10 min, c: 15 min.

[0025] Figure 6 The following are the variations of the silver film thickness, resistivity, and surface roughness with sputtering time in the examples: (a) variation of thickness with sputtering time; (b) variation of resistivity and surface roughness with sputtering time. Detailed Implementation

[0026] To more fully understand and demonstrate the technical solutions, objectives, and advantages of the present invention, the technical effects produced by the present invention will be further described in detail and completely below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. It should be noted that other embodiments obtained by those skilled in the art without departing from the concept of the present invention are all within the protection scope of the present invention.

[0027] Example 1

[0028] 1. Material preparation

[0029] Spherical gas-atomized silver powder with a particle size of 20–63 μm and a purity of not less than 99.99% is used as raw material.

[0030] 2. Additive manufacturing equipment

[0031] Using a PBF-LB / M system with a wavelength of 1070 nm, the above-mentioned spherical gas-atomized silver powder was subjected to laser additive manufacturing under argon protection to obtain a pure silver sputtering target. The process parameters are as follows:

[0032] The laser power P is 400W;

[0033] The scanning speed v is 900–1000 mm / s;

[0034] The scanning interval h is 0.09–0.13 mm;

[0035] The powder layer thickness t is 30 μm;

[0036] It is also proposed to control the ratio of scanning interval to scanning speed (h / v) within (0.9~1.3)×10 -4 Within a certain range, it serves as a key process control indicator, replacing the traditional volumetric energy density (Ev) parameter.

[0037] The pure silver sputtering target sample prepared in Example 1 was densified and its structure characterized, such as... Figures 1 to 6As shown, the prepared target material has a relative density greater than 99.5%, a grain size of 3.7 μm, a surface roughness of less than 12 μm, and a hardness increased to 52.4 HV. Magnetron sputtering verified that the film deposition rate of the target material can stably reach 31.8 nm / min, with uniform sputtering raceway area, a groove depth of 202.1 μm, and no obvious defects.

[0038] like Figure 2 As shown in Figure a, within the data regions indicated by the two yellow dashed boxes, the relative densities of green point 1 (v = 1000 mm / s, h = 0.09 mm) and purple point 1 (v = 900 mm / s, h = 0.09 mm) are approximately 15% higher than those of black point 3 (v = 600 mm / s, h = 0.2 mm) and red point 2 (v = 600 mm / s, h = 0.2 mm), despite their similar energy densities. This indicates that simultaneously increasing the scanning speed and decreasing the scanning spacing can significantly improve the relative density of Ag sputtering target samples prepared by PBF-LB / M.

[0039] According to the formula for calculating volumetric energy density (Ev) E v = P / vht, where P is the laser power (W), v is the scanning speed (mm / s), h is the scanning distance (mm), and t is the powder layer thickness (μm). When other variables remain constant, increasing the scanning speed will correspondingly increase the energy density. For example... Figure 4 As shown in the red area, when P = 400 W and h = 0.2 mm, adjusting the scanning speed causes the energy density to increase from 95.2 J / mm². 3 Increased to 166.7 J / mm 3 The relative density increased from 77.6% to 85.7%, corresponding to an increase in energy density of 75.1% (ΔE = 71.5 J / mm). 3 The relative density only increased by 8.1% when P = 370 W and h = 0.2 mm. Similarly, when P = 370 W and h = 0.2 mm, the energy density increased from 88.1 J / mm². 3 Increased to 123.3 J / mm 3 The relative density increased from 77.9% to 86.5%, and the energy density increased by 39.9% (ΔE = 35.2 J / mm²). 3 The relative density increased by 8.6%.

[0040] In contrast, with a fixed laser power and scanning speed (P = 400 W, v = 800 mm / s), adjusting the scanning spacing increased the energy density from 92.6 J / mm². 3 Increased to 185.2 J / mm 3 The relative density increased from 94.5% to 97.9%, although the energy density increased by 100% (ΔE = 92.6 J / mm²). 3However, the relative density only increased by 3.4%. These results indicate that the energy density increase brought about by adjusting the scanning spacing has a relatively weak effect on improving the relative density of Ag samples; in contrast, the effect of increasing energy density by optimizing the scanning speed on relative density is more significant. Therefore, in the PBF-LB / M process, the density of Ag sputtering target samples is more sensitive to changes in scanning speed than to adjustments in the scanning spacing.

[0041] In the experimental data of P = 400W, h / v was selected as the independent variable, and its relationship with the relative density of Ag was plotted, as shown below. Figure 2 As shown in b. The scatter plot shows that when the h / v value is high (2.5E-04 to 4.0E-04), the relative density of the Ag sample is low (<85%); when the h / v value decreases to about 1.0E-04, the relative density of the sample increases significantly, approaching 100%. By performing linear fitting on the data, the following regression equation is obtained ( Figure 2 (b, red line):

[0042] y = -8.13E-04x + 107.67 (1)

[0043] Where y is the relative density and x is the h / v value. The fitting correlation coefficient R0 2 =0.81, indicating a good linear fit. According to this formula, reducing the h / v value to approximately 1.0E-04 increases the relative density to nearly 100%, which is consistent with... Figure 2 The trend in a is consistent, thus verifying the rationality and scientific validity of the proposed h / v value as one of the key parameters for regulating the Ag target density.

[0044] The surface morphology of the Ag target sample was characterized using confocal microscopy, and the results are as follows: Figure 3 As shown, with increasing scanning speed and decreasing scanning spacing, the surface roughness of the silver sample increased from 6.31 μm to 11.53 μm. The main reason for the increase in roughness is the increase in energy density (from 95.2 J / mm²). 3 Rising to 148.1 J / mm 3 This is caused by the fact that, at higher energy densities, some spherical particles melt and adhere to the surface, reducing the overall surface quality, such as... Figure 3 As shown in Figure a. In contrast, under lower energy density conditions, the laser energy is mainly concentrated within the scanning trajectory, without affecting the powder outside the trajectory, thus forming a smoother surface, such as... Figure 3 As shown in b. Although increasing the scanning speed and decreasing the scanning spacing increases surface roughness, the surface of the Ag sample remains relatively smooth compared to other PBF-LB / M prepared metallic materials. However, under this combination of parameters, the relative density of the Ag sample decreases to 77.6%, accompanied by the appearance of more unfused defects.

[0045] Figure 4 The Vickers microhardness of Ag sputtering target samples prepared by different processes was compared. The results showed that the silver sample prepared by PBF-LB / M achieved a hardness of 52.4 HV, which is 85.8% and 45.1% higher than that of the conventionally cold-rolled (CR, 28.2 HV) and annealed cold-rolled (CA, 36.1 HV) samples, respectively, fully verifying the grain refinement strengthening effect brought about by laser additive manufacturing.

[0046] To evaluate the sputtering performance of Ag targets prepared by PBF-LB / M, this invention systematically characterizes the microstructure and properties of the sputtered Ag thin films, as well as the structural changes of the target material itself before and after sputtering. SEM and AFM were used to analyze the surface morphology and microstructure of the Ag thin films to ensure the reliability and comprehensiveness of the results. Figure 5 SEM and AFM images of silver films at different sputtering times are shown. The results show that with the extension of sputtering time, the surface particle size and micro-undulations of the Ag film gradually increase, and the surface roughness (Ra) increases from 2.1 nm at 5 minutes to 3.6 nm at 10 minutes, and further increases to 4.0 nm at 15 minutes, showing a continuous upward trend.

[0047] Figure 6 This demonstrates the relationship between sputtering time and the thickness, resistivity, and surface roughness of the silver film. For example... Figure 6 As shown in Figure a, the film thickness increases linearly with deposition time, and the sputtering rate remains stable at 31.8 nm / min within the 5 to 15 minute interval. The empirical relationship can be expressed as:

[0048] T = 31.8t + 2.93 (2)

[0049] Where T and t represent the film thickness (nm) and sputtering time (min), respectively. This linear relationship is consistent with literature reports, indicating that under isothermal substrate conditions, film growth is controlled by a stable surface diffusion process. Figure 6 b further reveals the evolution of thin film resistivity and surface roughness with sputtering time: as deposition time increases, surface roughness continuously increases, while resistivity gradually decreases. This trend indicates that although increased roughness leads to enhanced electron scattering, the overall electrical conductivity is still improved with increased film thickness and reduced porosity defects.

[0050] During thin film growth, internal stress is triggered by a complex coupling effect between composition, thickness, and deposition conditions. For high-mobility metals such as Au, Pd, and Ag, the nucleation and growth process typically follows the Volmer-Weber three-dimensional island model. Initially, the deposited atoms form isolated clusters on the substrate, creating a three-dimensional island structure. As deposition continues, these clusters merge into a continuous thin film. This transformation enhances conductivity, changing the film from an insulating state to a conductive state.

[0051] In summary, the laser additive manufacturing method for high-performance pure silver sputtering targets of this invention can not only significantly improve the microstructure and surface quality of Ag targets, but also effectively reduce the amount of precious metals used and production costs. It has significant technical advantages and engineering application potential, providing theoretical basis and practical reference for the additive manufacturing of high-performance precious metal targets, and laying the foundation for subsequent industrialization and application in high-end electronic devices such as OLEDs, capacitors, and optoelectronic films.

[0052] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A laser additive manufacturing method for a high-performance pure silver sputtering target, characterized in that, Includes the following steps: (1) Use spherical gas-atomized silver powder as raw material; (2) The spherical gas-atomized silver powder was laser-additively manufactured using a PBF-LB / M system under an inert atmosphere. The process parameters for the laser additive manufacturing included: laser power of 400W, scanning speed v of 900–1000 mm / s, scanning spacing h of 0.09–0.13 mm, and powder layer thickness of 30 μm, while simultaneously satisfying h / v = 0.9 × 10⁻⁶. -4 ~1.3×10 -4 By controlling the process parameters, pure silver sputtering targets were obtained.

2. The laser additive manufacturing method for the high-performance pure silver sputtering target according to claim 1, characterized in that, In step (1), the spherical atomized silver powder has a particle size of 20-63 μm and a purity of not less than 99.99%.

3. The laser additive manufacturing method for the high-performance pure silver sputtering target according to claim 1, characterized in that, In step (2), the wavelength of the PBF-LB / M system is 1070nm.

4. The laser additive manufacturing method for the high-performance pure silver sputtering target according to claim 1, characterized in that, In step (2), the inert gas is argon.

5. The laser additive manufacturing method for the high-performance pure silver sputtering target according to claim 1, characterized in that, In step (2), the relative density of the pure silver sputtering target is greater than 99.5%.

6. The laser additive manufacturing method for the high-performance pure silver sputtering target according to claim 1, characterized in that, In step (2), the grain size of the pure silver sputtering target is less than 4 μm.

7. The laser additive manufacturing method for the high-performance pure silver sputtering target according to claim 1, characterized in that, In step (2), the surface roughness of the pure silver sputtering target is less than 12 μm.

8. The laser additive manufacturing method for the high-performance pure silver sputtering target according to claim 1, characterized in that, In step (2), the hardness of the pure silver sputtering target is 52.4 HV.

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