A method for welding a tungsten target material by chemical vapor deposition

Abstract

The application relates to the technical field of semiconductors, in particular to a tungsten target material welding method by chemical vapor deposition, which comprises the following steps: preparing a target blank, a solder and a back plate, the target blank is a columnar crystal structure tungsten plate prepared by chemical vapor deposition, the back plate is integrally configured as a flat plate, and a matching slot is formed on the surface of the back plate, and four solder pools are designed on the surface of the slot. The surface of the slot of the back plate and the welding surface of the target blank are respectively subjected to surface treatment, and a transition layer is formed on the welding surface of the target blank by coating. The back plate and the target blank are heated at a preset temperature, so that the solders respectively placed on the surfaces of the back plate and the target blank are melted. The surfaces of the slot of the back plate and the transition layer of the target blank are infiltrated with the molten solders, and the molten solders in the slot of the back plate are excessive. The transition layer of the target blank is embedded into the slot of the back plate and is pressed tightly, so that part of the solders overflow from the slot. Heating is stopped and cooling is carried out, and a welded target material is obtained. The back plate and the target blank are respectively infiltrated with the molten solders and then welded at a lower temperature, so that the risk of the target blank being crushed during the welding cooling process is reduced.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a method for welding tungsten targets using chemical vapor deposition. Background Technology

[0002] With the rapid development of third-generation semiconductor technology, the manufacturing process of integrated circuit chips is constantly evolving towards smaller feature sizes and higher integration levels. The preparation and supply of related materials have gradually become one of the key factors restricting the development of the industry. Tungsten materials have excellent thermal and electrical conductivity, low resistivity, and stable performance at high temperatures. Therefore, they are widely used in semiconductor devices as via filling materials, wire materials, and isolation layers between silicon and aluminum.

[0003] As semiconductor device dimensions continue to shrink and process precision requirements increase, higher demands are being placed on sputtering targets in terms of purity, relative density, and microstructure uniformity. Currently, tungsten target blanks are often prepared using powder metallurgy, but due to limitations in raw tungsten powder and sintering processes, it is difficult to consistently achieve a semiconductor target purity of 5N+, thus limiting chip yield. However, using tungsten plates prepared by chemical vapor deposition (CVD) as target blanks offers the advantage of extremely high purity (7N+) and extremely high density (greater than 19.20 g / cm³). 3 It also features a more uniform microstructure, making it suitable for sputtering targets in advanced processes above 5nm. Furthermore, the high-temperature, high-pressure chemical vapor deposition process exhibits a high deposition rate, effectively improving the preparation efficiency of tungsten targets.

[0004] However, chemical vapor deposition tungsten plates have a columnar crystalline structure along their thickness, resulting in high hardness, poor plasticity, and brittleness, making them more prone to cracking during welding. Traditional brazing methods have the following problems: the solder is usually placed between the target blank and the backing plate for co-heating, requiring the design of suitable solder guides, which complicates the process; to ensure that the solder fully melts and wets the surfaces of the target blank and the backing plate, high temperatures are usually required, leading to accelerated oxidation of the backing plate.

[0005] Meanwhile, due to residual stress after backplate machining, the backplate will bulge towards the fitting groove during welding heating and will remain bulging after cooling. When the thickness of the backplate is small or the diameter is large, the bulge caused by residual stress is large, resulting in a large distance between the target blank edge and the backplate. The solder cannot completely fill the gap between the backplate and the target blank. At this time, the connection force between the backplate and the target blank is small, and the target blank is prone to falling off. Summary of the Invention

[0006] The purpose of this invention is to provide a method for welding tungsten targets using chemical vapor deposition.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A method for welding tungsten targets using chemical vapor deposition includes: Prepare a target blank, solder and backplate. The target blank is a tungsten plate with a columnar crystal structure prepared by chemical vapor deposition. The backplate is made of copper alloy and has a flat plate structure. The surface of the backplate has a fitting groove that matches the target blank. A recessed solder pool is formed on the surface of the fitting groove. The surfaces of the fitting groove of the back plate and the welding surface of the target blank are respectively surface treated, and the welding surface of the target blank is coated to form a transition layer; The backplate and the target blank are heated at a preset temperature respectively, so that the solder placed on the surface of the backplate and the target blank respectively melts. The preset temperature is any value between 200°C and 250°C. The surface of the mating groove of the back plate and the surface of the transition layer of the target blank are respectively wetted with the solder in a molten state, and an excess of molten solder is added into the mating groove of the back plate; The target blank is at least partially embedded in the fitting groove of the back plate, with the transition layer facing the surface of the fitting groove, and the back plate and the target blank are pressed together, so that a portion of the solder overflows from the fitting groove; Stop heating and cool to room temperature to complete the welding.

[0008] Optionally, the difference between the total thickness of the back plate and the depth of the fitting groove is taken as a first value, and the ratio of the diameter of the fitting groove to the first value is any value between 20 and 35.

[0009] Optionally, the solder pool is an annular structure concentrically arranged with the fitting groove, and the ratio of the first value to the depth of the solder pool is any value between 30 and 50, the outer diameter of the solder pool is the same as the diameter of the fitting groove, and the ratio of the width of the solder pool to the diameter of the fitting groove is any value between 0.05 and 0.1.

[0010] Optionally, the solder pool includes a first annular solder pool and a second annular solder pool, wherein the first annular solder pool and the second annular solder pool are arranged radially at intervals along the interlocking groove and the distance between the first annular solder pool and the second annular solder pool is any value between 60mm and 80mm, the centers of the first annular solder pool, the second annular solder pool and the interlocking groove coincide, the ratio of the first value to the depth of the solder pool is any value between 30 and 50, and the cross-sectional width of the solder pool is any value between 25mm and 40mm.

[0011] Optionally, the solder pool is a spiral groove formed at the bottom of the fitting groove. The spiral groove extends outward from the central region of the fitting groove along a spiral line, and the spiral center of the spiral groove coincides with the center of the fitting groove. The ratio of the first value to the depth of the solder pool is any value between 30 and 50. The radial distance between adjacent rings of the spiral groove is any value between 20mm and 50mm. The cross-sectional width of the solder pool is any value between 25mm and 40mm.

[0012] Optionally, the solder pool includes a plurality of square grooves arranged in an array, the spacing between two adjacent square grooves is any value between 25mm and 40mm, the groove width of the square groove is any value between 20mm and 50mm, and the ratio of the first value to the depth of the square groove is any value between 30 and 50.

[0013] Optionally, the preset temperature is any value between 200℃ and 250℃.

[0014] Optionally, the material of the transition layer includes at least one of aluminum, nickel, titanium, vanadium, and their alloys.

[0015] Optionally, when the transition layer is composed of a titanium alloy, the mass percentage of titanium in the transition layer is any value between 85% and 95%.

[0016] Optionally, the surface treatment includes sandblasting and degreasing / deoxidizing cleaning.

[0017] Optionally, the particle size of the sand used for sandblasting is any one of #16, #20, #24, #30, #36, #46, and #60, and the roughness after sandblasting is any one of 3μm to 7μm.

[0018] Optionally, the solder includes one or more of indium, tin, and tin-silver-copper alloys.

[0019] The beneficial effects of this invention are as follows: By providing a solder pool in the fitting groove, this application increases the capacity of the fitting groove to hold liquid solder, thereby reducing the risk of gaps between the target blank edge and the back plate, and simultaneously increasing the contact area between the solder and the back plate. This reduces the problem of difficulty in connecting the target blank edge and the back plate due to the protrusion in the middle of the back plate, and helps to improve the welding quality.

[0020] Heating the target blank and backplate separately melts the solder placed on their surfaces before bonding them together. This helps reduce the temperature of the target blank and backplate during bonding and alleviates the problem of backplate oxidation during heating.

[0021] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0022] Figure 1 This is a flowchart of the chemical vapor deposition tungsten target welding method shown in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the back plate structure shown in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the back plate structure shown in Embodiment 2 of the present invention; Figure 4 This is a schematic diagram of the back plate structure shown in Embodiment 3 of the present invention; Figure 5 This is a schematic diagram of the back plate structure shown in Embodiment 4 of the present invention; Figure 6 This is an ultrasonic testing image of the tungsten target obtained by welding in Comparative Example 7 of the present invention.

[0023] Legend: 1-backplate, 11-fitting groove, 12-solder pool, 121-first annular solder pool, 122-second annular solder pool, 123-square groove. Detailed Implementation

[0024] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] Figure 1 This is a flowchart of the chemical vapor deposition tungsten target welding method shown in Embodiment 1 of the present invention. Figure 2 This is a schematic diagram of the backplate structure shown in Embodiment 1 of the present invention. Figure 3 This is a schematic diagram of the back plate structure shown in Embodiment 2 of the present invention. Figure 4 This is a schematic diagram of the back plate structure shown in Embodiment 3 of the present invention. Figure 5 This is a schematic diagram of the back plate structure shown in Embodiment 4 of the present invention. Figure 6 This is an ultrasonic testing image of the tungsten target obtained by welding in Comparative Example Six of the present invention.

[0029] like Figure 1 As shown, this invention application protects a method for welding tungsten targets using chemical vapor deposition, comprising: S1. Prepare the target blank, solder and backplate 1. The target blank is a tungsten plate with columnar crystal structure prepared by chemical vapor deposition. The backplate 1 is made of copper alloy and has a flat plate structure. The surface has a fitting groove 11 that matches the target blank. The bottom part of the fitting groove 11 is recessed to form a solder pool 12.

[0030] S2. Surface treatment is performed on the surface of the fitting groove 11 of the back plate 1 and the welding surface of the target blank, and a coating is applied to the welding surface of the target blank to form a transition layer.

[0031] S3. Heat the backplate 1 and the target blank at a preset temperature respectively, so that the solder placed on the surface of the backplate 1 and the target blank respectively melts.

[0032] S4. The surface of the mating groove 11 of the backplate 1 and the surface of the transition layer of the target blank are respectively wetted with molten solder, and an excess of molten solder is added into the mating groove 11 of the backplate 1.

[0033] S5. The target blank is at least partially embedded in the fitting groove 11 of the back plate 1, so that the transition layer faces the surface of the fitting groove 11, and the back plate 1 and the target blank are pressed together, so that some solder overflows from the fitting groove 11.

[0034] S6. Stop heating and cool to obtain the target material.

[0035] It should be noted that the surface of the backplate 1 has residual stress caused by mechanical cutting. Under the action of residual stress, the middle part of the backplate 1 will bulge towards the fitting groove 11 after heating, and will remain bulging after cooling. When the thickness of the backplate 1 is small or the diameter is large, the bulge caused by residual stress is large, resulting in a large distance between the edge of the target blank and the backplate 1. The solder cannot completely fill the gap between the backplate 1 and the target blank. At this time, the connection force between the backplate 1 and the target blank is small, and the target blank is prone to falling off. Setting the solder pool 12 will further reduce the thickness of the middle part of the backplate 1, but since the depth of the solder pool 12 is small, the effect on the degree of bulging in the middle part of the backplate 1 is negligible.

[0036] In this embodiment, by providing a solder pool 12, the capacity of the fitting groove 11 to hold liquid solder is increased, thereby reducing the risk of gaps between the target blank edge and the back plate 1. Simultaneously, the contact area between the solder and the back plate 1 is increased, improving the bonding strength between the back plate 1 and the target blank. In some embodiments, the target blank is at least partially embedded in the fitting groove 11 of the back plate 1, and the fitting groove 11 is filled with molten solder. By providing excess solder, sufficient solder filling is ensured between the back plate 1 and the target blank, which helps to guarantee the connection strength.

[0037] In addition, surface treatment is performed on the target blank and back plate 1 respectively to form a transition layer on the surface of the target blank, which is not easy to wet, and sufficient wetting is performed before bonding, which helps to improve the connection strength between the target blank and back plate 1. The target blank and back plate 1 are heated separately to melt the solder placed on the surface of the target blank and back plate 1 respectively, and then the target blank and back plate 1 are bonded together, which helps to reduce the temperature of the target blank and back plate 1 during bonding. In conventional brazing methods, the solder is usually sandwiched between the target blank and back plate 1 and heated together. In order to ensure sufficient wetting of the solder, a temperature much higher than the melting point of the solder is usually required. In this invention, the target blank and back plate 1 are heated separately and wetting treatment is performed to improve the connection ability of the solder with the target blank and back plate 1, thereby reducing the preset temperature required by the heater and alleviating the oxidation problem in the back plate welding process.

[0038] In some embodiments, the difference between the total thickness of the back plate 1 and the depth of the fitting groove 11 is used as a first value, and the ratio of the diameter of the fitting groove 11 to the first value is any value between 30 and 35, for example, any value among 30, 31, 32, 33, 34, and 35. By constraining the ratio of the thickness corresponding to the fitting groove 11 to the diameter of the back plate 1, it helps to prevent excessive deformation caused by residual stress due to the thickness corresponding to the fitting groove 11 being too small, thus affecting the welding quality.

[0039] like Figure 2As shown, in some embodiments, the solder pool 12 is an annular structure concentrically arranged with the fitting groove 11, and the ratio of the first value to the depth of the solder pool 12 is any value between 30 and 50, for example, any value among 30, 35, 40, 45 and 50. The outer diameter of the solder pool 12 is the same as the diameter of the fitting groove 11, and the ratio of the width of the solder pool 12 to the diameter of the fitting groove 11 is any value between 0.05 and 0.1, for example, any value among 0.05, 0.06, 0.07, 0.08, 0.09 and 0.1.

[0040] In this embodiment, by setting the solder pool 12 as a circular annular structure concentric with the fitting groove 11, and making the outer diameter of the solder pool 12 the same as the diameter of the fitting groove 11, the supplementary solder can be preferentially arranged in the edge area of ​​the fitting groove 11. This allows for targeted soldering at locations where the target edge deformation is greater and the interface gap is more likely to increase during welding, thereby reducing problems such as incomplete soldering, missing solder, or decreased bonding strength in the edge area. Simultaneously, the circular solder pool 12 structure has a simple processing path and stable forming, which can reduce the overall solder usage while ensuring the edge repair welding effect, avoiding overflow, inclusions, or increased costs caused by excessive solder application across the entire area.

[0041] like Figure 3 As shown, in some embodiments, the solder pool 12 includes a first annular solder pool 121 and a second annular solder pool 122. The first annular solder pool 121 and the second annular solder pool 122 are arranged radially at intervals along the fitting groove 11, and the distance between the first annular solder pool 121 and the second annular solder pool 122 is any value between 60mm and 80mm, for example, any value between 60mm, 70mm and 80mm. The centers of the first annular solder pool 121, the second annular solder pool 122 and the fitting groove 11 coincide. The ratio of the first value to the depth of the solder pool 12 is any value between 30 and 50, for example, any value between 30, 35, 40, 45 and 50. The width of the solder pool 12d cross-section is any value between 25mm and 40mm, for example, any value between 25mm, 30mm, 35mm and 40mm.

[0042] In this embodiment, by setting a first annular solder pool 121 and a second annular solder pool 122 arranged radially at intervals and concentric with the interlocking groove 11, graded solder replenishment areas can be formed at different radial positions of the interlocking groove 11. This allows the solder to be replenished to the surrounding interface from multiple annular storage areas during the welding heating and pressure process, adapting to the deformation gradient and interface gap differences that exist from the center to the edge of the back plate 1. The distance between the first annular solder pool 121 and the second annular solder pool 122 is controlled within the range of 60mm-80mm, which can avoid solder accumulation caused by excessively dense solder pools 12, and can also avoid insufficient local replenishment caused by excessively large spacing, thereby improving the radial welding uniformity of the welding interface and the overall bonding reliability.

[0043] like Figure 4 As shown, in some embodiments, the solder pool 12 is a spiral groove formed at the bottom of the fitting groove 11. The spiral groove extends outward from the central region of the fitting groove 11 along a spiral line, and the spiral center of the spiral groove coincides with the center of the fitting groove 11. The ratio of the first value to the depth of the solder pool 12 is any value between 30 and 50, for example, any value between 30, 35, 40, 45 and 50. The radial spacing between adjacent spiral grooves is any value between 20mm and 50mm, for example, any value between 20mm, 30mm, 40mm and 50mm. The cross-sectional width of the solder pool 12 is any value between 25mm and 40mm, for example, any value between 25mm, 30mm, 35mm and 40mm.

[0044] In this embodiment, by setting the solder pool 12 as a spiral groove extending outward from the central region of the interlocking groove 11, a continuous solder storage and flow path can be formed within the interlocking groove 11. This allows the solder to gradually spread along the spiral path and replenish different radial regions under the action of welding pressure and temperature, reducing the problem of discontinuous replenishment caused by isolated local distribution of solder. The limitation of the radial spacing and cross-sectional width of adjacent rings can take into account both solder storage capacity and flow resistance, ensuring sufficient solder compensation at the interface gap while avoiding excessive concentrated flow of solder, thereby improving the continuity of solder distribution, sufficient interface filling, and consistent welding bonding.

[0045] like Figure 5 As shown, in some embodiments, the solder pool 12 includes a plurality of square grooves 123 arranged in an array. The spacing between two adjacent square grooves 123 is any value between 25mm and 40mm, for example, any value among 25mm, 30mm, 35mm and 40mm. The groove width of the square groove 123 is any value between 20mm and 50mm, for example, any value among 20mm, 30mm, 40mm and 50mm. The ratio of the first value to the depth of the square groove 123 is any value between 30 and 50, for example, any value among 30, 35, 40, 45 and 50.

[0046] In this embodiment, by setting the solder pool 12 as a plurality of square grooves 123 arranged in an array, multiple discrete and uniformly distributed local material storage units can be formed within the fitting groove 11. This allows each area to receive solder replenishment nearby during the welding pressure process, improving the problem of local missing solder caused by local flatness errors, uneven pressure, or small gaps. The spacing and width of adjacent square grooves 123 are controlled within a preset range, which can limit the amount of solder stored in a single groove while ensuring the solder replenishment coverage rate, reducing the risk of large-scale solder flow, accumulation, or overflow, thereby improving the local filling ability of the welding interface and the overall welding uniformity.

[0047] In this embodiment, by constraining the ratio of the thickness of the interlocking groove 11 to the depth of the solder pool 12, it prevents the solder pool 12 from being too deep, causing solder waste, or even excessive deformation of the middle of the backplate 1, and also prevents the solder pool 12 from being too shallow, resulting in insufficient buffering capacity. In some embodiments, the preset temperature is any value between 200℃ and 250℃, for example, any value among 200℃, 210℃, 230℃, and 250℃. Combining the size ratio of the backplate and the target blank, by selecting a preset temperature that matches the thermal expansion coefficients of tungsten and copper, the pressure of the sidewall of the interlocking groove 11 on the sidewall of the target blank is reduced. This pressure is sufficient to achieve mechanical interlocking between the backplate 1 and the target blank, but does not reach the limit that would cause the columnar crystal structure of the tungsten plate to break. This helps to apply the tungsten plate prepared by CVD to the preparation of the target material, thereby obtaining a tungsten film with higher purity and improving the quality of microelectromechanical devices.

[0048] In some embodiments, when the transition layer is composed of a titanium alloy, the mass percentage of titanium in the titanium alloy is any value between 85% and 95%, that is, the mass percentage of titanium in the titanium alloy can be 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, or 95%, or any other value between 85% and 95%. In a preferred embodiment, the mass percentage of titanium in the titanium alloy is 90%.

[0049] In some embodiments, the surface treatment includes sandblasting and degreasing / deoxidation cleaning. Sandblasting roughens the surface, which helps increase the contact area and improve the connection strength.

[0050] In some embodiments, the particle size of the sand used for blasting is any value among #16, #20, #24, #30, #36, #46, and #60, and the roughness after blasting is any value among 3μm to 7μm, for example, any value among 3μm, 4μm, 5μm, 6μm, and 7μm.

[0051] In some embodiments, the solder comprises one or more of indium, tin, and tin-silver-copper alloys.

[0052] Please refer to the following examples for details.

[0053] Example 1: Please see Figure 1 The preferred embodiment of this application shows a chemical vapor deposition tungsten target welding method, which includes: S1. Prepare the target blank, solder and backplate 1. The target blank is a tungsten plate with columnar crystal structure prepared by chemical vapor deposition. The backplate 1 is made of copper alloy and has a flat plate structure. The surface has a fitting groove 11 that matches the target blank. The bottom part of the fitting groove 11 is recessed to form a solder pool 12.

[0054] S2. Surface treatment is performed on the surface of the fitting groove 11 of the back plate 1 and the welding surface of the target blank, and a coating is applied to the welding surface of the target blank to form a transition layer.

[0055] S3. Heat the backplate 1 and the target blank at a preset temperature respectively, so that the solder placed on the surface of the backplate 1 and the target blank respectively melts.

[0056] S4. The surface of the mating groove 11 of the backplate 1 and the surface of the transition layer of the target blank are respectively wetted with molten solder, and an excess of molten solder is added into the mating groove 11 of the backplate 1.

[0057] S5. The target blank is at least partially embedded in the fitting groove 11 of the back plate 1, so that the transition layer faces the surface of the fitting groove 11, and the back plate 1 and the target blank are pressed together, so that some solder overflows from the fitting groove 11.

[0058] S6. Stop heating and cool to obtain the target material.

[0059] In step S1, the target blank is prepared by CVD and cut into a smooth tungsten plate. In this embodiment, the solder used is 3N indium solder, which is purchased, and the backplate 1 is cut from oxygen-free copper blank.

[0060] Please see Figure 2 The backplate 1 has an overall circular plate structure with a diameter of 404 mm and a total thickness of 11 mm. A circular fitting groove 11 is formed on one side surface of the backplate 1. The fitting groove 11 is coaxial with the backplate 1, has a diameter of 336 mm, and a depth of 0.5 mm. The bottom surface of the fitting groove 11 is partially recessed, forming a concentric annular solder pool 12 coaxial with the fitting groove 11. The solder pool 12 has an outer diameter of 336 mm, a depth of 0.3 mm, and a width of 21 mm.

[0061] In step S2, the surface treatment includes sandblasting and degreasing / oxidation cleaning.

[0062] The degreasing and deoxidation cleaning of the target blank includes the degreasing and deoxidation cleaning of the back plate 1, which includes soaking in a special cleaning agent, soaking in isopropanol, and dehydration and drying.

[0063] The sandblasting process for both the target blank and the back plate 1 was identical, using 16-mesh white corundum abrasive grains, with a roughness controlled to approximately 5 μm. The transition layer was composed of a titanium alloy, with titanium comprising approximately 90% by mass, aluminum approximately 6% by mass, and vanadium approximately 4% by mass.

[0064] In step S3, the back plate 1 and the target blank are heated using a heating table. The back plate 1 and the target blank are placed with the fitting groove 11 and the welding surface facing upwards, respectively. 200g of solder is added to the fitting groove 11, and 180g of solder is placed on the surface of the transition layer. In this embodiment, the heating temperature of the heating table, i.e., the preset temperature, is set to 200℃, and the heating is continued until the solder melts.

[0065] In step S4, molten solder is applied to the surface of the fitting groove 11 of the back plate 1 and the surface of the transition layer of the target blank, respectively, so that the solder fully wets the surface of the fitting groove 11 and the surface of the transition layer. Solid solder is then added to the fitting groove 11 and melted, so that the fitting groove 11 is filled with molten solder and the surface of the solder liquid bulges slightly.

[0066] In step S5, the target blank is embedded into the fitting groove 11 with the transition layer facing downward, and a pressure block with a mass of about 50 kg is placed on top of the target blank to press it down. At this time, some solder overflows from the fitting groove 11.

[0067] In step S6, the heating stage is turned off, allowing the backplate 1, target blank, and solder to cool naturally to room temperature, thus obtaining the target material. Since the surface of the target material is not wetted by solder, the solid solder formed by the cooling and solidification of the overflowing liquid solder can be separated by simple mechanical means and can be reused. Ultrasonic testing of the welding rate of the target material obtained in this embodiment showed a welding rate of approximately 99%, which meets the requirements for target material use.

[0068] The target blank obtained in this experiment has a relatively flat side surface, and the middle of the side surface of the back plate 1 is slightly convex and arc-shaped. It can be mechanically polished and shaped into a circular piece with flat surfaces on both sides before being applied to magnetron sputtering, or it can be directly applied to magnetron sputtering.

[0069] Example 2: The only difference between this embodiment and Embodiment 1 is that, in this embodiment, the backplane solder pool structure in step S1 is solder pool 12 (see...). Figure 3 The concentric circle trajectory spacing on the bottom surface of the fitting groove 11 is 70mm, and the width of the rectangular groove of the solder pool is 40mm. The target welding rate obtained in this embodiment is approximately 99%, similar to that in Embodiment 1.

[0070] Example 3: The only difference between this embodiment and Embodiment 1 is that, in this embodiment, the backplane solder pool structure in step S1 is solder pool 12 (see...). Figure 4 The bottom surface of the solder pool in the fitting groove 11 has a spiral pitch of 20 mm and a width of 40 mm. The target welding rate obtained in this embodiment is approximately 99%, similar to that in Embodiment 1.

[0071] Example 4: The only difference between this embodiment and Embodiment 1 is that, in this embodiment, the backplane solder pool structure in step S1 is solder pool 12 (see...). Figure 5 The bottom surface of the fitting groove 11 has a solder pool with a grid-like distribution of rectangular grooves. The grid is square with a side length of 30 mm, and the width of the rectangular groove of the solder pool is 40 mm. The target welding rate obtained in this embodiment is approximately 99%, similar to that in Embodiment 1.

[0072] Comparative Example 1: The only difference between this comparative example and Example 1 is that in step S1 of this comparative example, the back plate 1 surface is not provided with solder pool 12, which leads to unstable bonding between the target blank and the back plate 1 in step S5. The gap between the edge of the target blank and the back plate 1 is large, and the obtained target welding rate is about 73%, less than 95%. Moreover, the separation area is concentrated at the edge of the target blank, which does not meet the requirements for the use of the target material.

[0073] Comparative Example 2: The only difference between this comparative example and Example 1 is that the depth of the solder pool 12 of the backplate 1 in step S1 of this comparative example is 0.8 mm. The target bonding rate obtained in this comparative example is about 98%, similar to that of Example 1, but more solder is used than in Example 1, resulting in solder waste.

[0074] Comparative Example 3: The only difference between this comparative example and Example 1 is that the depth of the solder pool 12 of the back plate 1 in step S1 of this comparative example is 0.1 mm. Due to the small depth of the solder pool 12, the deformation buffering capacity is limited, resulting in unstable bonding between the target blank and the back plate 1 in step S5. The gap between the edge of the target blank and the back plate 1 is large, and the obtained target welding rate is about 93%, which is less than 95%. Moreover, the separation area is concentrated at the edge of the target blank, which does not meet the requirements for the use of the target material.

[0075] Comparative Example 4: The only difference between this comparative example and Example 1 is that in step S1 of this comparative example, no solder pool 12 is formed on the surface of the back plate 1. During the cooling process in step S6, the tungsten target material deforms significantly due to welding stress, and insufficient solder results in a target material welding rate of only 87%, which does not meet the requirements for target material use.

[0076] Comparative Example 5: The only difference between this comparative example and Example 1 is that in this example, no pressure block is used to press the target blank in step S5. During the cooling process in step S6, there is no vertical load restriction, which causes the target material to deform, requiring an additional shaping step, reducing efficiency, and introducing a machining step, which increases the risk of cracking of the tungsten target blank.

[0077] Comparative Example 6: The only difference between this comparative example and Example 1 is that in step S4 of this example, only wetting is performed, and no additional solder is added to the fitting groove 11. The tungsten target material obtained by welding in this comparative example was subjected to ultrasonic non-destructive testing; the test results can be found in [link to relevant documentation]. Figure 6 As can be seen in the image, there are large white areas, which are the areas where welding was not completed. This indicates that there are obvious air bubbles on the weld surface. Analysis shows that the weld success rate is only 80%, indicating poor welding quality that does not meet the requirements. The air bubbles are caused by insufficient solder in the solder pool 12 during the cooling process in step S6, which leads to the introduction of gas during welding and the formation of air bubbles, thus resulting in a decrease in the weld success rate.

[0078] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0079] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for welding tungsten targets using chemical vapor deposition, characterized in that, include: Prepare a target blank, solder and backplate (1). The target blank is a tungsten plate with columnar crystal structure prepared by chemical vapor deposition. The backplate (1) is made of copper alloy, has a flat plate structure, and has a fitting groove (11) on its surface that fits the target blank. A recessed solder pool (12) is formed at the bottom of the fitting groove (11). The surfaces of the fitting groove (11) of the back plate (1) and the welding surface of the target blank are respectively surface treated, and the welding surface of the target blank is coated to form a transition layer; The backplate (1) and the target blank are heated at a preset temperature respectively, so that the solder placed on the surface of the backplate (1) and the target blank respectively melts; The surface of the fitting groove (11) of the back plate (1) and the surface of the transition layer of the target blank are respectively wetted with the solder in a molten state, and an excess of molten solder is added into the fitting groove (11) of the back plate (1); The target blank is at least partially embedded in the fitting groove (11) of the back plate (1), with the transition layer facing the surface of the fitting groove (11), and the back plate (1) and the target blank are pressed together, so that a portion of the solder overflows from the fitting groove (11); Stop heating and cool to room temperature to obtain the target material.

2. The chemical vapor deposition tungsten target welding method as described in claim 1, characterized in that, The difference between the total thickness of the back plate (1) and the depth of the fitting groove (11) is taken as the first value, and the ratio of the diameter of the fitting groove (11) to the first value is any value between 20 and 35.

3. The chemical vapor deposition tungsten target welding method as described in claim 2, characterized in that, The solder pool (12) is a circular annular structure concentrically arranged with the fitting groove (11), and the ratio of the first value to the depth of the solder pool (12) is any value between 30 and 50. The outer diameter of the solder pool (12) is the same as the diameter of the fitting groove (11), and the ratio of the width of the solder pool (12) to the diameter of the fitting groove (11) is any value between 0.05 and 0.

1.

4. The chemical vapor deposition tungsten target welding method as described in claim 2, characterized in that, The solder pool (12) includes a first annular solder pool (121) and a second annular solder pool (122). The first annular solder pool (121) and the second annular solder pool (122) are arranged radially at intervals along the fitting groove (11), and the distance between the first annular solder pool (121) and the second annular solder pool (122) is any value between 60mm and 80mm. The centers of the first annular solder pool (121), the second annular solder pool (122) and the fitting groove (11) coincide. The ratio of the first value to the depth of the solder pool (12) is any value between 30 and 50. The width of the rectangular groove of the solder pool (12) is any value between 25mm and 40mm.

5. The chemical vapor deposition tungsten target welding method as described in claim 2, characterized in that, The solder pool (12) is a spiral groove formed on the bottom surface of the fitting groove (11). The spiral groove extends outward along a spiral line from the central area of ​​the fitting groove (11), and the spiral center of the spiral groove coincides with the center of the fitting groove (11). The ratio of the first value to the depth of the solder pool (13) is any value between 30 and 50. The radial distance between adjacent rings of the spiral groove is any value between 20 mm and 50 mm. The cross-sectional width of the solder pool (12) is any value between 25 mm and 40 mm.

6. The chemical vapor deposition tungsten target welding method as described in claim 2, characterized in that, The solder pool (12) includes a plurality of square grooves (123) arranged in an array. The distance between two adjacent square grooves (123) is any value between 25mm and 40mm. The groove width of the square groove (123) is any value between 20mm and 50mm. The ratio of the first value to the depth of the square groove (123) is any value between 30 and 50.

7. The chemical vapor deposition tungsten target welding method as described in claim 1, characterized in that, The preset temperature is any value between 200℃ and 250℃.

8. The chemical vapor deposition tungsten target welding method according to any one of claims 1-7, characterized in that, The material of the transition layer includes at least one of aluminum, nickel, titanium, vanadium, and their alloys; When the transition layer is composed of a titanium alloy, the mass percentage of titanium in the titanium alloy is any value between 85% and 95%.

9. The chemical vapor deposition tungsten target welding method as described in claim 1, characterized in that, The surface treatment includes sandblasting and degreasing and deoxidation cleaning, and the roughness after sandblasting is any value between 3μm and 7μm.

10. The chemical vapor deposition tungsten target welding method as described in claim 1, characterized in that, The solder includes one or more of indium, tin, and tin-silver-copper alloys.

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