Ion beam composite sputtering target assembly with diamond coated three-dimensional skeleton and method of manufacturing the same

Abstract

The application discloses an ion beam composite sputtering target assembly with a diamond coating three-dimensional skeleton and a preparation method thereof, which comprises a composite sputtering target, a cooling back plate and a transition layer, wherein the composite sputtering target comprises a three-dimensional skeleton with a diamond coating and a main sputtering material filled in the three-dimensional skeleton; the three-dimensional skeleton is a honeycomb structure or a net structure; and the transition layer is arranged between the composite sputtering target and the cooling back plate and is a Cu-Mo-Cu composite layer structure. Compared with the prior art, the application has better heat shock resistance and structural stability.

Description

Technical Field

[0001] This invention relates to the field of high-end laser optical coating, specifically to an ion beam composite sputtering target assembly with a diamond-coated three-dimensional framework and its preparation method. Background Technology

[0002] Ion beam sputtering (IBS), also known as ion beam deposition (IBD), is a physical vapor deposition (PVD) technique renowned for its ability to produce high-performance thin films. Thin films prepared using IBS typically exhibit high density, amorphous properties, excellent environmental stability, low optical absorption, and low scattering loss. Therefore, IBS technology is widely used in the fabrication of optical coatings with stringent performance requirements, such as those used in laser systems, precision optical components, and fiber optic communications.

[0003] In a typical IBS process, a high-energy, wide-beam ion source generates and guides an ion beam to bombard a solid target. The ion bombardment causes atoms or clusters of atoms on the target surface to be impacted and sputtered. These sputtered particles are then deposited onto a substrate in a vacuum environment to form a thin film. Some IBS systems also include a separate auxiliary ion source whose ion beam directly acts on the growing film to achieve densification or modification.

[0004] As a critical consumable component in this process, the material and properties of the target directly affect the film quality. In optical coating applications, targets are typically made of high-purity dielectric materials, such as oxides, nitrides, or fluorides, and are formed into a monolithic solid disk structure through hot pressing or sintering processes. The typical dimensions of such targets range from 100 mm to 500 mm in diameter and 5 mm to 25 mm in thickness.

[0005] However, existing monolithic dielectric targets have inherent technical drawbacks, primarily due to their low thermal conductivity. During sputtering, most of the ion beam's energy is converted into heat within the target. For example, an ion beam with 2keV energy and a 500mA current can inject up to 1 kilowatt of power into a localized area of ​​the target. Due to the target's low heat dissipation efficiency, the following problems arise:

[0006] 1. Target failure due to thermal stress: A significant thermal gradient forms between the working surface of the target subjected to ion bombardment and the back surface of the target, which is usually water-cooled. The thermal stress generated by this thermal gradient can easily cause brittle ceramic targets to crack or even shatter, resulting in process interruption and equipment downtime, and increasing production costs.

[0007] 2. Unstable and limited deposition rate: Local overheating of the target material can alter its sputtering yield, causing the film deposition rate to become unstable or uneven over time. Furthermore, to prevent target material from cracking due to thermal stress, the power density of the incident ion beam must be limited during operation, which directly restricts the improvement of the deposition rate.

[0008] 3. Arcing causes thin film defects: Since the target material is a dielectric, the charge of incident positive ions will accumulate on its surface. When the surface potential accumulates to the breakdown threshold, it will discharge instantaneously in the form of an electric arc. This process will eject macroscopic particles, which will deposit on the substrate and form defects in the optical coating, reducing product yield.

[0009] Existing technologies address these issues by improving the bonding layer between the target and the high thermal conductivity cooling backplate, or by using reactive sputtering with a metal target. However, even with these improvements, the fundamental problem of low bulk thermal conductivity of the material remains.

[0010] Therefore, existing ion beam sputtering targets need to be improved. Summary of the Invention

[0011] The first technical problem to be solved by the present invention is to provide an ion beam composite sputtering target assembly with a diamond-coated three-dimensional skeleton that has good thermal shock resistance and structural stability, in light of the above-mentioned technical status.

[0012] The second technical problem to be solved by the present invention is to provide a method for preparing an ion beam composite sputtering target assembly in light of the above-mentioned technical status.

[0013] The technical solution adopted by the present invention to solve the first technical problem mentioned above is: an ion beam composite sputtering target assembly with a diamond-coated three-dimensional framework, characterized in that it comprises:

[0014] A composite sputtering target includes a three-dimensional skeleton with a diamond coating and a main sputtering material filled in the three-dimensional skeleton; the three-dimensional skeleton has a honeycomb structure or a mesh structure.

[0015] Cooling backplate; and

[0016] A transition layer is disposed between the composite sputtering target and the cooling backplate, and is a Cu–Mo–Cu composite layer structure.

[0017] Preferably, the cooling back plate is provided with a cooling channel that spirals from the central region of the cooling back plate to the edge region, and is provided with a water inlet and a water outlet, the water inlet being located in the central region and the water outlet being located in the edge region.

[0018] Preferably, the main sputtering material is a dielectric optical material.

[0019] Preferably, the main sputtering material is one or more of silicon dioxide, tantalum pentoxide, or hafnium dioxide.

[0020] Preferably, the composite sputtering target further includes a dense coating layer covering the three-dimensional skeleton.

[0021] For ease of connection, preferably, a metal bonding layer is provided between the composite sputtering target and the transition layer, and between the transition layer and the cooling backplate.

[0022] To balance thermal conductivity and sputtering uniformity, the three-dimensional framework is preferably a conductive structure extending from the target surface to the cooling backplate. The cooling backplate is equipped with an external grounding interface for connecting the charge discharged from the three-dimensional framework to the ground. The grounded diamond-coated conductive framework provides a rapid dissipation channel for the positive ion charge accumulated on the target surface, effectively preventing excessive accumulation of surface potential. This significantly reduces the frequency and intensity of arcing events, thereby greatly reducing thin film defects caused by macroscopic particles and significantly improving the yield of optical components.

[0023] The technical solution adopted by the present invention to solve the second technical problem mentioned above is: a method for preparing an ion beam composite sputtering target assembly, characterized by comprising the following steps:

[0024] S1. A three-dimensional skeleton is formed by laser sintering, and a diamond coating is formed on the surface of the three-dimensional skeleton.

[0025] S2. Fill the three-dimensional skeleton covered with diamond coating with main sputtering material powder, and form a composite target structure by molding and hot isostatic pressing processes.

[0026] S3. Connect the composite target structure with the transition layer and the cooling backplate to form an integrated ion beam composite sputtering target assembly.

[0027] Compared with existing technologies, the advantages of this invention are as follows: A composite sputtering target is formed by integrating a three-dimensional skeleton with a highly thermally conductive diamond coating with the main sputtering material. The three-dimensional skeleton serves as an efficient internal heat conduction channel, rapidly dissipating the localized high temperatures generated during sputtering. This heat is then transferred through a transition layer and finally to a cooling backplate, where it is efficiently carried away. This complete, low-stress heat dissipation path from the internal three-dimensional skeleton to the external cooling backplate enhances the target's thermal shock resistance and structural stability, enabling it to withstand power densities far exceeding those of traditional targets. This results in a more stable and efficient sputtering process, leading to higher deposition rates and superior film quality. When this composite target assembly is installed in an ion beam sputtering system, it can withstand power densities >10 W / cm², exhibiting robustness, durability, and high power handling capability. The significant increase in power allows for a multiplied increase in film deposition rates, effectively shortening the single coating cycle and greatly improving the unit-time output value of expensive coating equipment while reducing the manufacturing cost per unit product. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the heat dissipation path in Example 1;

[0029] Figure 2 This is a schematic diagram of the electrical grounding path in Example 1;

[0030] Figure 3 This is a schematic diagram of the three-dimensional skeleton of Example 1;

[0031] Figure 4 This is a schematic diagram of the spiral cooling channel in Example 1. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0033] Example 1

[0034] This embodiment demonstrates an ion beam composite sputtering target assembly with a diamond-coated three-dimensional framework.

[0035] like Figure 1 As shown, the target assembly, from top to bottom, includes a composite sputtering target, a Cu-Mo-Cu transition layer 13, and a cooling backplate 15 with internal cooling channels. The composite sputtering target and the transition layer 13, as well as the transition layer 13 and the cooling backplate 15, are connected by a metal bonding layer 14. The composite sputtering target is composed of a main sputtering material 11 and a centrally recessed molybdenum three-dimensional framework 12 serving as a support structure.

[0036] The preparation method of the ion beam composite sputtering target assembly is as follows:

[0037] ① Preparation of composite sputtering targets:

[0038] S1. Three-dimensional framework 12: Molybdenum metal powder with a purity ≥99.95% is used to fabricate a hexagonal honeycomb array three-dimensional framework 12 using laser sintering technology. The upper surface of the three-dimensional framework 12 is raised around the edges. Through process control, the porosity, pore size, and rib wall thickness of the framework can be adjusted to simultaneously meet the requirements of sputtering uniformity and high thermal conductivity. Subsequently, a diamond coating layer with a thickness of 50–200 µm is uniformly deposited on the surface of the framework ribs using chemical vapor deposition (CVD). This CVD method is known to those skilled in the art and will not be described in detail here. Figure 3 As shown, the three-dimensional skeleton 12 is composed of regular hexagonal units, arranged in a periodic and orderly manner. In the figure, (a) shows the planar arrangement, (b) shows the interlayer stacking arrangement, and (c) shows the three-dimensional skeleton 12 of the overall three-dimensional structure (the concave part in the middle is not shown).

[0039] (a) Within a single layer, the skeleton units are arranged in a honeycomb pattern with hexagons as the basic repeating units. Adjacent units are connected by edges in the plane to form a two-dimensional periodic structure.

[0040] (b) In the direction perpendicular to the plane, each two-dimensional honeycomb layer is stacked in layers along the normal direction, and there is a regular misalignment between adjacent layers, so that the upper hexagonal unit is not completely located directly above the lower layer, but is translated laterally, thus forming a stable three-dimensional skeleton frame.

[0041] (c) After multi-layer stacking, the three-dimensional skeleton 12 forms a through-hole structure in three-dimensional space. This arrangement enhances the spatial connectivity and mechanical stability of the structure while maintaining high porosity.

[0042] S2. Target material composite: In the pores of the three-dimensional skeleton 12 covered with diamond layer, silica powder with a purity of ≥99.99% as the main sputtering material 11 is filled; then, a co-densification treatment is carried out by molding hot isostatic pressing sintering process, so that silica and three-dimensional skeleton 12 form a highly dense and firmly bonded integrated composite structure.

[0043] S3. Dense Covering Layer: On one side of the sputtering surface of the composite target, an additional dense covering layer formed of pure silicon dioxide is provided to cover the three-dimensional skeleton 12. This dense covering layer does not contain a metal skeleton and is integrally solidified with the lower composite target through hot pressing sintering. The main sputtering material 11 fills the pore structure of the three-dimensional skeleton 12 and covers the three-dimensional skeleton 12 to ensure the purity of the film in the early sputtering stage.

[0044] ② Preparation of transition layer 13 and cooling backplate 15:

[0045] The transition layer 13 is made of Cu-Mo-Cu sandwich composite material. The transition layer 13 is prepared as a whole by rolling diffusion welding process. Its thermal expansion coefficient shows a gradient continuous transition between the composite sputtering target and the cooling back plate 15, so it can effectively absorb the thermal stress between the two.

[0046] Preparation of cooling backplate 15: Cooling backplate 15 is made of oxygen-free copper material with a purity ≥99.995%, such as... Figure 4 As shown, it has an internal spiral single-loop cooling channel with a rectangular cross-section. The inlet 41 is located at the center of the cooling back plate 15, and the outlet 42 is located at the edge of the cooling back plate 15. This complex three-dimensional flow channel is directly milled into the copper billet using CNC precision machining technology, ensuring dimensional accuracy and surface quality. During operation, deionized cooling water with a temperature controlled at 20±1°C is introduced into the channel for continuous circulation and heat exchange.

[0047] ③ The composite sputtering target, transition layer 13, and cooling backplate 15 are all connected by low-temperature brazing using high-purity indium solder with a melting point of approximately 157°C in a vacuum environment, thereby forming a metal bonding layer 14. This low-temperature process avoids thermal damage to the material structure of each layer.

[0048] The working mechanism of the ion beam composite sputtering target assembly in this embodiment is as follows:

[0049] Heat dissipation path: Sputtering heat is first concentrated on the dense silica coating layer on the surface of the composite sputtering target, and then quickly captured by the highly thermally conductive molybdenum three-dimensional skeleton 12 below. The honeycomb-shaped three-dimensional skeleton 12 not only rapidly diffuses heat in-plane to prevent local overheating, but also efficiently conducts heat flow downwards in the vertical direction through diamond-coated ribs. After being smoothly transferred through the Cu-Mo-Cu transition layer 13, the heat is finally absorbed by the oxygen-free copper cooling backplate 15 and continuously carried away by the circulating cooling water in the internal spiral cooling channel, thereby ensuring the stability of the target's operating temperature.

[0050] Charge Discharge Path: The silica capping layer on the sputtering target surface is an insulator, but the molybdenum metal three-dimensional framework 12 embedded beneath it serves as an internal conductive channel, constructing a continuous three-dimensional discharge network from top to bottom. Charge accumulated during the process is conducted downwards through this three-dimensional discharge network, via the Cu-Mo-Cu transition layer 13, and finally reaches the highly conductive oxygen-free copper cooling backplate 15. Grounding holes pre-set on the side edge of the cooling backplate 15 can be connected to the equipment grounding system, achieving efficient charge discharge and preventing discharge breakdown caused by surface charge accumulation.

[0051] Example 2

[0052] This embodiment demonstrates an ion beam composite sputtering target assembly with a diamond-coated three-dimensional framework; its overall structure and connection method are the same as those in Embodiment 1, the main difference being the different material selection for the composite target.

[0053] The method for preparing an ion beam composite sputtering target assembly includes the following steps:

[0054] ① Preparation of composite sputtering targets:

[0055] S1, Three-dimensional framework 12: Tungsten metal powder with a purity of ≥99.95% is selected and laser sintered to prepare a hexagonal honeycomb-shaped concave three-dimensional framework 12 with a structure similar to that in Example 1, and a diamond coating of the same specifications is deposited.

[0056] S2, Target material composite: Hafnium dioxide powder with a purity of ≥99.99% is filled into the skeleton as the main sputtering material 11, and a high-density composite is formed by the same molding and hot isostatic pressing sintering process.

[0057] S3, Dense Covering Layer: On one side of the sputtering surface of the composite target, a dense covering layer formed by pure silicon dioxide main sputtering material 11 is provided to cover the three-dimensional skeleton 12, and is integrally solidified by hot pressing sintering.

[0058] ② Preparation of transition layer 13 and cooling back plate 15: Same as in Example 1, Cu-Mo-Cu transition layer 13 is prepared by rolling diffusion welding and oxygen-free copper spiral cooling back plate 15 is formed by CNC precision machining.

[0059] ③ The layers are connected by vacuum low-temperature brazing with high-purity indium solder to form a metal bonding layer 14.

Claims

1. An ion beam composite sputtering target assembly with a diamond-coated three-dimensional framework, characterized in that: include: The composite sputtering target includes a three-dimensional skeleton (12) with a diamond coating and a main sputtering material (11) filled in the three-dimensional skeleton (12); the three-dimensional skeleton (12) is a honeycomb structure or a mesh structure. Cooling backplate (15); and A transition layer (13) is disposed between the composite sputtering target and the cooling backplate (15), and is a Cu–Mo–Cu composite layer structure.

2. The ion beam composite sputtering target assembly with a diamond-coated three-dimensional framework according to claim 1, characterized in that: The cooling back plate (15) is provided with a cooling channel that spirals from the central region of the cooling back plate (15) to the edge region and is provided with a water inlet (41) and a water outlet. The water inlet (41) is located in the central region and the water outlet is located in the edge region.

3. The ion beam composite sputtering target assembly with a diamond-coated three-dimensional framework according to claim 1, characterized in that: The main sputtering material (11) is a dielectric optical material.

4. The ion beam composite sputtering target assembly with a diamond-coated three-dimensional framework according to claim 3, characterized in that: The main sputtering material (11) is one or more of silicon dioxide, tantalum pentoxide, or hafnium dioxide.

5. The ion beam composite sputtering target assembly with a diamond-coated three-dimensional framework according to claim 1, characterized in that: The main sputtering material (11) also includes a dense covering layer located on top of the three-dimensional skeleton (12) and covering the three-dimensional skeleton (12).

6. The ion beam composite sputtering target assembly with a diamond-coated three-dimensional framework according to claim 1, characterized in that: Metal bonding layers (14) are provided between the composite sputtering target and the transition layer (13), and between the transition layer (13) and the cooling backplate (15).

7. The ion beam composite sputtering target assembly with a diamond-coated three-dimensional framework according to claim 1, characterized in that: The three-dimensional skeleton (12) is a conductive structure and extends from the surface of the target material to the cooling back plate (15); the cooling back plate (15) is provided with an external grounding interface for connecting the charge exported by the three-dimensional skeleton (12) to the ground.

8. A method for preparing an ion beam composite sputtering target assembly according to any one of claims 1-7, characterized in that: Includes the following steps: S1. A three-dimensional skeleton (12) is formed by laser sintering, and a diamond coating is formed on the surface of the three-dimensional skeleton (12); S2. Fill the three-dimensional skeleton (12) covered with diamond coating with main sputtering material (11) powder, and form a composite target structure by molding and hot isostatic pressing process; S3. Connect the composite target structure with the transition layer (13) and the cooling backplate (15) to form an integrated ion beam composite sputtering target assembly.

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