Preparation method of high-utilization-rate noble metal target material and noble metal target material

Abstract

This invention discloses a method for preparing a high-utilization precious metal target and the precious metal target itself. The preparation method includes obtaining the final shape of the etched area based on the etching pattern of the etched area on the sputtering target surface; designing the target material into an annular protrusion structure opposite to the final shape of the etched area according to the target holder specifications of the sputtering coating machine, obtaining a first target material structure; dividing the first target material structure into multiple parts to obtain a second target material structure; and fabricating the target material based on the second target material structure. The above preparation method, by targeting the annular grooves formed by the continuous etching of the sputtering target surface, sets the target surface into an inverted annular protrusion structure, allowing the sputtering process to target the protrusions, thereby significantly reducing the initial overall thickness of the target material. By dividing the target material into multiple parts and using a splicing structure, both the sputtering effect is ensured, and the amount of precious metal used is further significantly reduced, lowering the initial investment in the target material and thus significantly improving the utilization rate of the target material.

Description

Technical Field

[0001] This invention relates to the field of precious metal target technology, and in particular to a method for preparing a high-utilization precious metal target and the precious metal target itself. Background Technology

[0002] Vacuum magnetron sputtering is widely used for surface coating of products, offering advantages such as being environmentally friendly, producing excellent film performance, and allowing for a wide range of film types. Among these, precious metal sputtering coating is an important type of coating material, widely used in aerospace, information technology, electronics, biomedicine, and decorative industries. To date, sputtering coatings in the decorative field mostly utilize planar targets. During sputtering, argon gas is ionized by impact, and the argon ions, under bias voltage, bombard the target surface at high speed, forming an etching layer. Because electrons are confined near the target surface, forming a ring-shaped etching zone of a certain width, the deepest etching occurs at the center of the zone. The etching gradually decreases in depth towards both sides, forming a U-shaped etching groove resembling a wide, shallow pit. Other parts of the target surface are rarely etched. However, once the center of the etching groove is etched through, the target material becomes unusable. Therefore, the utilization rate of this planar target material is less than 30%, which also affects the coating quality.

[0003] For precious metals, this low utilization rate significantly increases coating costs. It requires peeling the target material from the copper backing plate, sending it to a specialized refining plant for purification and recycling, and then using pure precious metals and intermediate alloys to formulate the target material. These processing steps all involve the loss of precious metals and processing costs. Therefore, how to quickly repair the target surface with high quality without affecting the coating quality has become a pressing problem for the industry. A few researchers have conducted related research and achieved some results. For example, patent CN1608141A discloses a method for repairing discarded sputtering targets. It uses hot isostatic pressing or HIP technology to fill the loss area of ​​the target with new sputtering target material to repair the discarded sputtering target. The above technology mainly addresses the problem of repairing targets after use. Although it improves the utilization rate of targets to some extent, it still has the following problems: First, the initial investment in targets is large. Since the structure of the targets is a traditional planar target, the thickness of each part of the target is uniform. However, to obtain a longer service life, the initial thickness of the target cannot be too thin. This leads to a surge in the precious metal weight of the sputtering targets, significantly increasing the one-time investment and capital costs for enterprises. For the jewelry industry, which is dominated by small and medium-sized enterprises, such an excessive one-time investment is difficult to bear. Secondly, the repair rate of the sputtering targets is limited. Because each repair can only fill the etched groove area, and the volume of the etched area is already small, the cost-effectiveness of repair is not significantly better than that of making new sputtering targets, and it is even more complicated than making new sputtering targets. For example, it is necessary to accurately obtain the shape of the etched groove and make a repair body that perfectly matches it. This is a very difficult project because the etched grooves on the sputtering target are irregular after use, and processing a repair body with good correspondence requires a high level of skill.

[0004] Studies have shown that rotating targets can significantly improve target utilization. However, existing coating equipment is based on planar targets, and modifying it to a rotating target structure presents significant technical challenges and requires substantial investment. Furthermore, rotating targets are difficult to manufacture. Moreover, during sputtering, the entire target surface exhibits numerous glow rings, preventing the formation of continuous banded glow and affecting the uniformity of the film. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, one of the objectives of this invention is to provide a method for preparing a high-utilization precious metal sputtering target. Addressing the problems of existing precious metal sputtering target structures and utilization rates, this method improves the target surface morphology. Based on the formation rules of the sputtering etching zone, a raised structure opposite to the etching zone is pre-formed on the target surface. Simultaneously, the thickness of the target substrate is significantly reduced. Through other structural design, this method ultimately ensures sputtering effectiveness while significantly reducing the amount of precious metal used, lowering the initial investment in the target, and significantly improving the utilization rate of the target.

[0006] One of the objectives of this invention is to provide a precious metal target material prepared using the above-mentioned method for preparing a precious metal target material with high utilization rate.

[0007] One of the objectives of this invention is achieved through the following technical solution:

[0008] A method for preparing a high-utilization precious metal target material includes the following preparation steps:

[0009] S1: Based on the etching pattern of the etched area on the sputtering target surface, the final shape of the etched area is obtained;

[0010] S2: Based on the target holder specifications of the sputtering coating machine, the target material is designed as an annular protrusion structure opposite to the final shape of the etched area, thus obtaining the first target material structure;

[0011] S3: Based on step S2, the first target structure is obtained. The first target structure is divided into multiple parts to obtain the second target structure.

[0012] S4: Based on step S3, obtain the second target structure and fabricate the target.

[0013] Further, in step S1, the specific operation steps are as follows: using an intercooled sputtering target, setting it into several segments, each segment having the same thickness and width, removing the target after a certain period of use, observing and detecting the morphology and contour of its surface using a laser confocal microscope, and stitching together the scanning results of each part to obtain the accurate morphology of the etched area, forming a dynamic evolution process of the etched groove morphology of the target surface under different usage times, that is, the etched pattern of the etched area on the sputtering target surface, which serves as the basis for target surface structure design and service life prediction, and obtaining the final shape of the etched area.

[0014] Furthermore, in step S2, the annular protrusion structure is designed with the highest point at the center of the sputtering trajectory, gradually transitioning towards the edge in a saddle shape. The remaining portion of the target material is flat, with the thickness of the flat portion controlled at 2–3 mm. The highest point of the target material is 5–10 mm higher than the flat portion. This design provides the target material with sufficient strength and resistance to deformation. In this step, the target surface morphology is improved. Based on the formation pattern of the sputtering etching zone, a protrusion structure opposite to the etching zone is pre-fabricated on the target surface. Simultaneously, the thickness of the target material base is significantly reduced, greatly decreasing the amount of precious metal used, thereby further reducing the initial investment in the target material.

[0015] Furthermore, the annular protrusion structure also includes: the back of the target material is designed to be flat, and it is completely in contact with the copper surface of the target holder of the sputtering coating machine. This design allows the cooling water in the target holder to cool the target material through the copper target, so that the target material does not change shape during the sputtering process.

[0016] Further, in step S3, the specific operation steps are as follows: the target material is set to indirect cooling, and the target material is divided into a top section, a bottom section, and several intermediate sections. The bottom surface of the target material and the joint surfaces between the various sections are milled flat using CNC. In the above design, due to the thermal stress generated by the target material during sputtering, in order to prevent warping deformation, the target material is divided into a top section, a bottom section, and several intermediate sections, each with the same thickness and width. By seamlessly splicing the various target material sections, a continuous target surface can be formed, which can form a continuous strip of glow during sputtering, ensuring the uniformity and quality of the coated film.

[0017] Furthermore, the number of intermediate segments is 6 to 12.

[0018] More preferably, step S3 further includes the following steps: using CNC to mill the surface of the copper backing plate flat, so that the bottom surface of the target segment is completely in contact with the surface of the copper backing plate, effectively ensuring the cooling effect of the target during sputtering, so as to further prevent deformation and warping. At the same time, the various segments of the target are seamlessly spliced ​​and firmly welded to the backing plate. In the end, the sputtering effect is guaranteed, the amount of precious metal used is greatly reduced, the initial investment of the target is reduced, and the utilization rate of the target is significantly improved.

[0019] Furthermore, in step S4, the target material is manufactured using a process of vacuum continuous casting, precision forging, vacuum annealing, precision molding, and precision milling.

[0020] More preferably, in step S4, the specific steps for manufacturing the target material are as follows:

[0021] (1) Preparation of molding mold

[0022] Forging dies for the top, bottom, and middle sections are made separately. The bottom of the die cavity of the top or bottom section is a concave arc ring, while the rest of the die is flat. The front of the middle section die has two parallel raised areas, while the rest of the die is flat, and the back of the die is flat.

[0023] In this step, the cavity wall of the forging die is provided with a draft angle of 3 to 5 degrees.

[0024] (2) Ingredients

[0025] The corresponding metallic material is obtained by formulating the ingredients according to the required material type and composition of the target.

[0026] In this step, the specific material preparation steps are as follows: For targets plated with pure gold, pure silver, or other pure precious metals, high-purity precious metals with a purity of 99.99% to 99.999% are used as raw materials; for precious metal alloy materials plated with 23K gold, 22K gold, 20K gold, 18K gold, 16K gold, 14K gold, 980 silver alloy, 950 silver alloy, 925 silver alloy, or other precious metal alloys, high-purity precious metals with a purity of 99.99% to 99.999% and suitable intermediate alloys are used as raw materials. Taking into account the target material's color requirements and the melting and burning loss rate, the content of the main precious metal elements is calculated according to a positive deviation of 0.2 to 1.0 wt% to ensure that the final color of the target material meets the lower limit requirement. For example, when preparing an 18K gold alloy, the theoretical gold content is 75 wt%. When preparing the alloy, the gold content is calculated based on 75.3 to 75.8 wt%, and the amount of intermediate alloy added is 24.2 wt% to 24.7 wt%.

[0027] (3) Smelting and casting

[0028] The metal materials are smelted using a vacuum continuous casting machine and cast into continuously cast slabs with a thickness of 10-15 mm and a width of 50-60 mm.

[0029] The specific operating steps in this process are as follows: The raw materials are placed in the melting chamber, and a vacuum of 5–15 Pa is applied. Then, high-purity argon gas (99.999% purity) is introduced, and the initial pressure is controlled at -0.04–-0.02 MPa. Heating is initiated to melt the metal. Under electromagnetic stirring, the chemical composition and temperature of the molten metal become uniform. The temperature of the molten metal is adjusted to 50–100°C above its melting point, and the casting device is started to produce a continuously cast slab.

[0030] (4) Segment milling

[0031] The continuous casting slab is cut into several segments using an electrical discharge wire cutting device. The length and width of the segments are 0.2 to 0.5 mm smaller than the length and width of the mold cavity, respectively.

[0032] (5) Die forging

[0033] Graphite emulsion release agent is sprayed into the forging die cavity, and the blank is placed into the top section, bottom section and middle section forging die respectively, and forged in a forging press.

[0034] In this step, for materials with excellent ductility, such as pure gold and gold alloys with a purity of 18K or higher, cold forging is used directly. For high-strength alloy materials such as 16K gold and 14K gold, to ensure complete forming, the material is heated to 650–700℃ and then hot-forged. To reduce the degree of oxidation of the material during heating, heating is preferably carried out in an inert atmosphere such as pure argon or pure nitrogen, with a gas flow rate of 4–6 ml / min.

[0035] (6) Trimming

[0036] The flash of the die-forged target blank is punched off using a trimming die and a punching machine.

[0037] (7) Annealing

[0038] The forged target billet is annealed in a continuous non-oxidizing tunnel furnace at a temperature of 650–750°C. The tunnel chain mesh runs at a speed of 0.5–2 m / min and the ammonia flow rate is 6–10 ml / min. The ammonia flow rate is set at 2–4 ml / min at the inlet and outlet of the tunnel furnace.

[0039] In this step, the profiles are kept at a temperature below 150°C after exiting the tunnel furnace.

[0040] (8) CNC machining

[0041] After annealing, the forged target blank is milled on a CNC machine to control the surface roughness of the target surface to 0.8-1.6μm, the flatness of the target bottom surface to within 30μm, and the straightness of the joint surface of the target segments to within 20μm.

[0042] (9) Welding

[0043] The target material is positioned on a copper backing plate. Indium solder paste is applied to the back of the target material segments, which are then arranged in a close sequence. The solder paste is then heated to melt it, and after cooling, the target material segments are firmly soldered to the copper backing plate.

[0044] (10) Assembly

[0045] The copper backing plate is then assembled onto the target mount and tightened with countersunk bolts. Finally, the target mount is installed on the coating machine, and the target material is ready for use.

[0046] The second objective of this invention is achieved by the following technical solution:

[0047] A precious metal target material, characterized in that it is prepared by the above-described method for preparing a high-utilization precious metal target material.

[0048] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0049] The high-utilization precious metal target preparation method of the present invention, through the process of continuously etching the annular groove formed on the sputtering target surface, sets the target surface into an inverted annular protrusion structure according to the degree of etching of different parts, so that the sputtering process is excited at the protrusion, thereby significantly reducing the initial overall thickness of the target material. At the same time, the target material is set into multiple parts, and through the splicing structure, the sputtering effect is guaranteed, and the amount of precious metal used is further significantly reduced, reducing the initial investment of the target material, thereby significantly improving the utilization rate of the target material. Attached Figure Description

[0050] Figure 1 The morphology of a local etched area on the target surface in Example 1;

[0051] Figure 2 The etching morphology of section 1 in Example 1;

[0052] Figure 3 for Figure 2 The etching profile of section 1 shown;

[0053] Figure 4 The etching morphology of cross section 2 in Example 1;

[0054] Figure 5 for Figure 4 The etching profile of section 2 shown;

[0055] Figure 6 The etching morphology of section 3 in Example 1;

[0056] Figure 7 for Figure 6 The etching profile of section 3 shown;

[0057] Figure 8 The etching morphology of section 4 in Example 1;

[0058] Figure 9 for Figure 8 The etching profile of section 4 shown;

[0059] Figure 10 The etching morphology of section 5 in Example 1;

[0060] Figure 11 for Figure 10 The etching profile of section 5 is shown. Detailed Implementation

[0061] The present invention will now be further described in conjunction with specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0062] Example 1: Preparation of a Hard Gold Sputtering Target

[0063] 1. Determine the etching pattern and final shape of the etched area on the sputtering target surface.

[0064] The morphology and contour of the target surface were observed using a laser confocal microscope, and the scan results of each part were stitched together to obtain the accurate morphology of the etched area. For example... Figure 1The image shows the morphology of a local etched area on the target surface. To more clearly demonstrate the morphology of the etched area on the target surface, five cross-sectional images of the etched morphology and their corresponding contours were taken, as shown below. Figures 2-11 As shown.

[0065] 2. Design the target shape

[0066] Based on the target holder specifications of the sputtering coating machine, the target material is designed as a ring-shaped protrusion with a morphology opposite to that of the sputtering etching. The highest point is located at the center of the sputtering trajectory, gradually transitioning towards the edge in a saddle shape. The remaining parts of the target material are flat, with a thickness controlled at 3mm. The highest point of the target material is 10mm higher than the flat surface of the target. The target material possesses sufficient strength and resistance to deformation. The back side of the target material is designed as a flat surface, completely fitting the copper surface of the target holder. Cooling water inside the target holder cools the target material through the copper target, ensuring that the target material remains unchanged during the sputtering process.

[0067] 3. Design of target installation structure

[0068] To reduce the initial investment in precious metal materials, the target material is designed for indirect cooling. Due to the thermal stress generated during sputtering, the target is divided into a top section, a bottom section, and eight intermediate sections to prevent warping. CNC milling is used to flatten the bottom surface of the target and the mating surfaces between the sections. Seamless splicing of the target sections creates a continuous target surface, resulting in continuous banded glow during sputtering and ensuring the uniformity and quality of the coated film. CNC milling of the copper backing plate ensures complete contact between the bottom surface of the target sections and the copper backing plate, effectively guaranteeing cooling during sputtering and preventing warping.

[0069] 4. Target material preparation

[0070] (1) Preparation of molding mold

[0071] Separate forging dies are made for the top (bottom) section and the middle section. The bottom of the die cavity of the top (bottom) section is a concave arc ring, while the rest is flat. The front of the middle section die has two parallel concave areas, while the rest is flat, and the back of the die is flat. The die cavity wall has a 5° draft angle.

[0072] (2) Ingredients

[0073] Using 99.999% pure gold and commercially available 5G hard gold powder as raw materials, the mixture is prepared in a ratio of 99.93:0.07 for high-purity gold and 5G hard gold powder to ensure that the final color of the target material meets the requirements of 999 gold plating.

[0074] (3) Smelting and casting

[0075] Hard metal is smelted using a vacuum continuous casting machine and continuously cast into slabs with a thickness of 15 mm and a width of 60 mm. Raw materials are placed in the melting chamber, a vacuum of 15 Pa is drawn, and then high-purity argon gas (99.999% purity) is introduced, with the initial pressure controlled at -0.03 MPa. Heating is initiated to melt the metal, and the molten metal is stirred electromagnetically to homogenize its chemical composition and temperature. The temperature of the molten metal is adjusted to 80°C above its melting point, and the casting device is activated to produce continuously cast slabs.

[0076] (4) Segment milling

[0077] The continuous casting slab was cut into 12 segments by wire electrical discharge machining. The length and width of the segments were 0.4 mm smaller than the length and width of the mold cavity.

[0078] (5) Die forging

[0079] Graphite emulsion release agent is sprayed into the die cavity of the forging die. The blank is then placed into the top (bottom) section forging die and the middle section forging die, and forged in a forging press.

[0080] (6) Trimming

[0081] The flash of the die-forged target blank is punched off using a trimming die and a punching machine.

[0082] (7) Annealing

[0083] The forged target billet was continuously annealed in a non-oxidizing tunnel furnace at a temperature of 700℃. The tunnel chain mesh running speed was 1 m / min, and the ammonia flow rate was 8 ml / min. The ammonia flow rate was set at 3 ml / min at both the inlet and outlet of the tunnel furnace. After exiting the tunnel furnace, the profile temperature was below 150℃.

[0084] (8) CNC machining

[0085] After annealing, the forged target blank is milled on a CNC machine to control the surface roughness of the target surface to 1.6μm, the flatness of the target bottom surface to within 28μm, and the straightness of the joint surface of the target segments to within 18μm.

[0086] (9) Welding

[0087] The target material is positioned on a copper backing plate. Indium solder paste is applied to the back of the target material segments, which are then arranged in a close sequence. The solder paste is then heated to melt it, and after cooling, the target material segments are firmly soldered to the copper backing plate.

[0088] (10) Assembly

[0089] Assemble the copper backing plate onto the target mount and tighten it with countersunk bolts. Install the target mount onto the coating machine, and the target material is ready for use.

[0090] Example 2: Preparation of 18K Gold Target Material

[0091] 1. Determine the etching pattern and final shape of the etched area on the sputtering target surface.

[0092] The morphology and contour of the target surface were observed using a laser confocal microscope, and the scanning results of each part were stitched together to obtain the accurate morphology of the etched area.

[0093] 2. Design the target shape

[0094] Based on the target holder specifications of the sputtering coating machine, the target material is designed as a ring-shaped protrusion with a morphology opposite to that of the sputtering etching. The highest point is located at the center of the sputtering trajectory, gradually transitioning towards the edge in a saddle shape. The remaining parts of the target material are flat, with a thickness controlled at 2.5 mm. The highest point of the target material is 8 mm higher than the flat surface of the target. The target material possesses sufficient strength and resistance to deformation. The back side of the target material is designed as a flat surface, completely fitting the copper surface of the target holder. Cooling water inside the target holder cools the target material through the copper target, ensuring that the target material remains unchanged during the sputtering process.

[0095] 3. Design of target installation structure

[0096] To reduce the initial investment in precious metal materials, the target material is designed for indirect cooling. Due to the thermal stress generated during sputtering, the target is divided into a top section, a bottom section, and ten intermediate sections to prevent warping. CNC milling is used to flatten the bottom surface of the target and the mating surfaces between the sections. Seamless splicing of the target sections creates a continuous target surface, resulting in continuous banded glow during sputtering and ensuring the uniformity and quality of the coated film. CNC milling of the copper backing plate ensures complete contact between the bottom surface of the target sections and the copper backing plate, effectively guaranteeing cooling during sputtering and preventing warping.

[0097] 4. Target material preparation

[0098] (1) Preparation of molding mold

[0099] Separate forging dies are made for the top (bottom) section and the middle section. The bottom of the die cavity of the top (bottom) section is a concave arc ring, while the rest is flat. The front of the middle section die has two parallel concave areas, while the rest is flat, and the back of the die is flat. The die cavity wall has a 4° draft angle.

[0100] (2) Ingredients

[0101] The ingredients are formulated according to the required material type and composition of the target material. High-purity gold with a purity of 99.99%, pure silver with a purity of 99.99%, and pure copper with a purity of 99.99% are used as raw materials. Taking into account the target material's purity requirements and the melting and burning loss rate, the purity is calculated based on a gold content of 75.5 wt%. Pure silver and pure copper are used as intermediate alloys, with a total addition of 24.5 wt%, and the weight ratio of silver to copper is 1:1.

[0102] (3) Smelting and casting

[0103] Pure gold, pure silver, and pure copper are smelted in a vacuum continuous casting machine and continuously cast into slabs 15 mm thick and 55 mm wide. The raw materials are placed in the melting chamber, evacuated to 10 Pa, and then filled with 99.999% pure argon gas, with the initial pressure controlled at -0.04 MPa. Heating is initiated to melt the metal, and the molten metal is stirred electromagnetically to homogenize its chemical composition and temperature. The temperature of the molten metal is adjusted to 50°C above its melting point, and the casting device is activated to produce continuously cast slabs.

[0104] (4) Segment milling

[0105] The continuous casting slab was cut into 8 segments by wire electrical discharge machining. The length and width of each segment were 0.2 mm smaller than the length and width of the mold cavity.

[0106] (5) Die forging

[0107] Graphite emulsion release agent is sprayed into the die cavity of the forging die. The blank is then placed into the top (bottom) section forging die and the middle section forging die, and forged in a forging press.

[0108] (6) Trimming

[0109] The flash of the die-forged target blank is punched off using a trimming die and a punching machine.

[0110] (7) Annealing

[0111] The forged target billet was continuously annealed in a non-oxidizing tunnel furnace at a temperature of 650℃. The tunnel chain mesh running speed was 0.5 m / min, and the ammonia flow rate was 6 ml / min. The ammonia flow rate was set at 2 ml / min at both the inlet and outlet of the tunnel furnace. After exiting the tunnel furnace, the profile temperature was below 120℃.

[0112] (8) CNC machining

[0113] After annealing, the forged target blank is milled on a CNC machine to control the surface roughness of the target surface to within 0.8μm, the flatness of the target bottom surface to within 20μm, and the straightness of the joint surface of the target segments to within 13μm.

[0114] (9) Welding

[0115] The target material is positioned on a copper backing plate. Indium solder paste is applied to the back of the target material segments, which are then arranged in a close sequence. The solder paste is then heated to melt it, and after cooling, the target material segments are firmly soldered to the copper backing plate.

[0116] (10) Assembly

[0117] Assemble the copper backing plate onto the target mount and tighten it with countersunk bolts. Install the target mount onto the coating machine, and the target material is ready for use.

[0118] Example 3: Preparation of 14K Gold Target Material

[0119] 1. Determine the etching pattern and final shape of the etched area on the sputtering target surface.

[0120] The morphology and contour of the target surface were observed using a laser confocal microscope, and the scanning results of each part were stitched together to obtain the accurate morphology of the etched area.

[0121] 2. Design the target shape

[0122] Based on the target holder specifications of the sputtering coating machine, the target material is designed as a ring-shaped protrusion with a morphology opposite to that of the sputtering etching. The highest point is located at the center of the sputtering trajectory, gradually transitioning towards the edge in a saddle shape. The remaining parts of the target material are flat, with a thickness controlled at 2mm. The highest point of the target material is 5mm higher than the flat surface of the target. The target material possesses sufficient strength and resistance to deformation. The back side of the target material is designed as a flat surface, completely fitting the copper surface of the target holder. Cooling water inside the target holder cools the target material through the copper target, ensuring that the target material remains unchanged during the sputtering process.

[0123] 3. Design of target installation structure

[0124] To reduce the initial investment in precious metal materials, the target material is designed for indirect cooling. Due to the thermal stress generated during sputtering, the target is divided into a top section, a bottom section, and six intermediate sections to prevent warping. CNC milling is used to flatten the bottom surface of the target and the mating surfaces between the sections. Seamless splicing of the target sections creates a continuous target surface, resulting in continuous banded glow during sputtering and ensuring the uniformity and quality of the coating. CNC milling of the copper backing plate ensures complete contact between the bottom surface of the target sections and the copper backing plate, effectively guaranteeing cooling during sputtering and preventing warping.

[0125] 4. Target material preparation

[0126] (1) Preparation of molding mold

[0127] Separate forging dies are made for the top (bottom) section and the middle section. The bottom of the die cavity of the top (bottom) section is a concave arc ring, while the rest is flat. The front of the middle section die has two parallel concave areas, while the rest is flat, and the back of the die is flat. The die cavity wall has a 3° draft angle.

[0128] (2) Ingredients

[0129] Using 99.99% pure gold and H152R commercial master alloy as raw materials, taking into account the target material's color requirements and smelting loss rate, the gold content was calculated with a positive deviation of 0.7wt%, i.e., based on a gold content of 59wt%, and the amount of master alloy added was 41wt%.

[0130] (3) Smelting and casting

[0131] The metallic material is melted and continuously cast into slabs with a thickness of 10 mm and a width of 50 mm using a vacuum continuous casting machine. The raw materials are placed in the melting chamber, evacuated to 5 Pa, and then filled with high-purity argon gas (99.999%), with the initial pressure controlled at -0.02 MPa. Heating is initiated to melt the metal, and the molten metal is stirred electromagnetically to homogenize its chemical composition and temperature. The temperature of the molten metal is adjusted to 100°C above its melting point, and the casting device is activated to produce continuously cast slabs.

[0132] (4) Segment milling

[0133] The continuous casting slab is cut into several segments by wire electrical discharge machining. The length and width of the segments are 0.5 mm smaller than the length and width of the mold cavity.

[0134] (5) Die forging

[0135] The billet is placed in a furnace filled with pure nitrogen and heated at a nitrogen flow rate of 5 ml / min and a heating temperature of 700℃. Graphite emulsion release agent is sprayed into the die cavity. The red-hot billet is then placed into the top (bottom) section forging die and the middle section forging die, and forged in a forging press.

[0136] (6) Trimming

[0137] The flash of the die-forged target blank is punched off using a trimming die and a punching machine.

[0138] (7) Annealing

[0139] The forged target billet was continuously annealed in a non-oxidizing tunnel furnace at a temperature of 720℃. The tunnel chain mesh running speed was 2 m / min, and the ammonia flow rate was 10 ml / min. The ammonia flow rate was set at 4 ml / min at both the inlet and outlet of the tunnel furnace. After exiting the tunnel furnace, the profile temperature was below 100℃.

[0140] (8) CNC machining

[0141] After annealing, the forged target blank is milled on a CNC machine to control the surface roughness of the target surface to within 0.8μm, the flatness of the target bottom surface to within 20μm, and the straightness of the joint surface of the target segments to within 15μm.

[0142] (9) Welding

[0143] The target material is positioned on a copper backing plate. Indium solder paste is applied to the back of the target material segments, which are then arranged in a close sequence. The solder paste is then heated to melt it, and after cooling, the target material segments are firmly soldered to the copper backing plate.

[0144] (10) Assembly

[0145] Assemble the copper backing plate onto the target mount and tighten it with countersunk bolts. Install the target mount onto the coating machine, and the target material is ready for use.

[0146] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for producing a high-utilization noble metal target material, characterized by, The preparation steps include the following: S1: Based on the etching pattern of the etched area on the sputtering target surface, the final shape of the etched area is obtained; S2: Based on the target holder specifications of the sputtering coating machine, the target material is designed as an annular protrusion structure opposite to the final shape of the etching area, resulting in the first target material structure; the annular protrusion structure is as follows: the highest point is set at the center of the sputtering trajectory, gradually transitioning to the edge in a saddle shape, and the rest of the target material is flat. The thickness of the flat part of the target material is controlled at 2-3 mm, and the highest point of the target material is 5-10 mm higher than the flat part of the target material. S3: Based on step S2, the first target structure is obtained. The first target structure is divided into multiple parts to obtain the second target structure. The specific operation steps are as follows: the target is set to indirect cooling mode. The target is divided into a top section, a bottom section and several middle sections. The bottom surface of the target and the joint surface between the various sections of the target are milled flat using CNC. S4: Based on step S3, obtain the second target structure and fabricate the target.

2. The method for preparing a high-utilization precious metal target material according to claim 1, characterized in that, In step S1, the specific operation steps are as follows: an intercooled sputtering target is used and it is set into several segments, each with the same thickness and width. The target is removed after a certain period of use, and its surface morphology and contour are observed and detected using a laser confocal microscope. The scanning results of each part are stitched together to obtain the accurate morphology of the etched area. The target surface etching results under different usage times form a dynamic evolution process of the etch groove morphology, which serves as the basis for target surface structure design and service life prediction, and the final shape of the etched area is obtained.

3. The method for preparing a high-utilization precious metal target material according to claim 1, characterized in that, The annular protrusion structure also includes: the back of the target material is designed as a flat surface, which is completely in contact with the copper surface of the target holder of the sputtering coating machine.

4. The method for preparing a high-utilization precious metal target material according to claim 1, characterized in that, The number of middle sections is 6 to 12.

5. The method for preparing a high-utilization precious metal target material according to claim 1, characterized in that, Step S3 also includes the following step: using CNC to mill the surface of the copper backing plate flat, so that the bottom surface of the target segment is completely attached to the surface of the copper backing plate.

6. The method for preparing a high-utilization precious metal target material according to claim 1, characterized in that, In step S4, the specific steps for fabricating the target material are as follows: (1) Preparation of molding mold Forging dies for the top, bottom, and middle sections are made separately. The bottom of the die cavity of the top or bottom section die is a concave arc ring, while the rest of the die is flat. The front of the middle section die has two parallel raised areas, while the rest of the die is flat, and the back of the die is flat. (2) Ingredients The corresponding metallic material is obtained by formulating the materials according to the required material type and composition of the target. (3) Smelting and casting The metal materials are smelted using a vacuum continuous casting machine and cast into continuous casting slabs with a thickness of 10-15 mm and a width of 50-60 mm. (4) Segment milling The continuous casting slab is cut into several segments using an electrical discharge wire cutting device. The length and width of the segments are 0.2 to 0.5 mm smaller than the length and width of the mold cavity, respectively. (5) Die forging Graphite emulsion release agent is sprayed into the forging die cavity, and the blank is placed into the top section, bottom section and middle section forging die respectively, and forged in a forging press. (6) Trimming The flash of the die-forged target blank is punched off using a trimming die and a punching machine. (7) Annealing The forged target billet is annealed in a continuous non-oxidizing tunnel furnace at a temperature of 650–750°C, with a tunnel chain running speed of 0.5–2 m / min and an ammonia flow rate of 6–10 ml / min. An ammonia flow rate of 2–4 ml / min is set at the tunnel furnace inlet and end outlet. (8) CNC machining After annealing, the forged target blank is milled on a CNC machine to control the surface roughness of the front side of the target material to 0.8-1.6μm, the flatness of the bottom side of the target material to within 30μm, and the straightness of the joint surface of the target material segment to within 20μm. (9) Welding The target material is positioned on a copper backing plate. Indium solder paste is applied to the back of the target material segments, which are then arranged in a close sequence. The solder paste is then heated to melt it, and after cooling, the target material segments are firmly soldered to the copper backing plate. (10) Assembly The copper backplate is assembled onto the target mount and tightened with countersunk bolts.

7. The method for preparing a high-utilization precious metal target material according to claim 6, characterized in that, In step (1), the cavity wall of the forging die is provided with a draft angle of 3-5°; in step (2), the specific material preparation steps are as follows: for the target material plated with pure gold or pure silver, high-purity precious metals with a purity of 99.99%-99.999% are used as raw materials; for precious metal alloy materials plated with 23K gold, 22K gold, 20K gold, 18K gold, 16K gold, 14K gold, 980 silver alloy, 950 silver alloy, and 925 silver alloy, high-purity precious metals with a purity of 99.99%-99.999% and suitable intermediate alloys are used as raw materials. The content of the main element is calculated according to a positive deviation of 0.2 to 1.0 wt% to ensure that the final color of the target material meets the lower limit requirement. In step (3), the specific operation steps are as follows: put the raw material into the melting chamber, evacuate to 5 to 15 Pa, then fill with high-purity argon gas with a purity of 99.999%, control the initial gas pressure to -0.04 to -0.02 MPa, start heating to melt the metal, and make the chemical composition and temperature uniform under the action of electromagnetic stirring. Adjust the temperature of the metal liquid to 50 to 100°C above the melting point, start the billet pulling device, and make a continuous casting slab.

8. A precious metal target material, characterized in that, It is prepared using the high-utilization precious metal target material preparation method as described in any one of claims 1-7.

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