Target Bonding Service
Introduction to the bonding method and process of sputtering target materials
Sputtering target material is a physical vapor deposition technique. It is the process in which ions generated by an ion source accelerate and aggregate in vacuum to form a high-speed ion beam, bombarding the solid surface. The ions exchange kinetic energy with the atoms on the solid surface, causing the atoms on the solid surface to leave the solid and deposit on the substrate surface. The integrity and combination rate of target material and backboard bonding can determine the performance and cost of the target material, so the requirements for target material bonding are relatively high. So how should we bind it? Below, Kejin Ultrasonic Equipment Factory will introduce the bonding method and process of target materials.
The main bonding modes of the target material
- Adhesive Combination01
- Silver adhesive bonding is a low-cost technology. The method is to use a special thermal conductive epoxy resin to bond the target material onto the back panel. This technology requires treatment of the surface and backplate of the target material. The adhesive target material has low residual stress and is easy to rework. Its tangential thermal resistance is relatively high, which limits the power density and deposition rate of the sputtering target material. This method is not effective.
- Solder Bonding02
- Compared to silver adhesive bonding, solder bonding has lower thermal resistance and can therefore operate at a higher deposition rate. The common solder filler is indium, which has high thermal conductivity, relatively low melting point and elastic modulus, and can reduce residual stress after bonding. Its low melting point also simplifies the rework of bonding and allows for the reuse of backboards. However, due to the difficulty of indium metal penetrating the copper backplate and inside the target material, it is easy to fall off the target. Therefore, ultrasonic waves need to be used to penetrate the metal indium into the backplate and inside the target material.
- High Temperature Welding03
- High temperature welding is a technology that combines brazing and diffusion welding. It needs to be operated above 500 ℃ and requires a vacuum or controllable atmosphere oven. Brazing is achieved by melting the brazing alloy at the joint to form the joint. Welding does not use fillers, but rather achieves bonding by heating the backing plate under high pressure to a temperature where it diffuses with the target material. This structure has low thermal resistance, usually close to or lower than the thermal resistance of the parent alloy, and allows for higher power density.
Notes on the use of bound target materials
- ● The sputtering temperature should not be too high
- ● The current needs to slowly increase
- ● The circulating cooling water should be below 35 degrees Celsius
- ● Appropriate target density
Uneven thermal conductivity can cause uneven sputtering of the target material (uneven film formation), as well as surface nodulation and discharge phenomena, which can cause uneven film formation. The color of the film layer shows differences, and the differences in the three silver products that affect the change of the dielectric layer are more significant, leading to an increase in the scrap rate of the coating. Therefore, the bonding quality of the target material has a significant impact on its application. In general, because the target material generates a large amount of heat during the sputtering process, but the heat dissipation of ceramic targets is relatively poor. If the bonding shows a large area with poor bonding, it is easy to show local heat accumulation during the sputtering process, and low melting point bonding data indium melts, leading to cracking or even falling of the target material.
The role of target material bonding
- ● Prevent uneven fragmentation of the target material due to heating. For example, brittle targets such as ITO, SiO2, ceramics, and sintered targets are prone to simple fragmentation when heated;
- ● Save costs and prevent deformation. If the target material is too expensive, it can be made thinner and bound to the back target to prevent deformation.
The bonding of target materials and the quality of lining tubes are crucial for target coating, which not only requires team awareness but also professionalism. Only in this way can a good film be plated.
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