There is a difference between the cooling water temperature used in production and the actual water temperature of the coating line, which leads to the formation of cracks in the target material during use. In general, minor cracks will not have a big impact on coating production. However, when the target has obvious cracks, the charge is easily concentrated on the edge of the crack, resulting in abnormal discharge on the surface of the target. Discharge will lead to slag falling, abnormal film formation, and increased product scrap.
Influencing factors of target crack formation
Crack formation usually occurs in ceramic sputtering targets (eg oxides, carbides, nitrides, etc.) and brittle material sputtering targets (eg chromium, antimony, bismuth, etc.).
Ceramic or brittle material targets always contain intrinsic stress. These internal stresses are generated during the target manufacturing process. Furthermore, these stresses cannot be completely eliminated by the annealing process, as it is an inherent property of these materials. During sputtering, the bombarding gas ions transfer their momentum to the target atoms, giving them enough energy to break free from the lattice. This exothermic momentum transfer increases the temperature of the target, possibly up to 1,000,000 degrees Celsius at the atomic level. These thermal shocks multiply the internal stresses already present in the target many times over. In this case, the target may develop cracks if proper heat dissipation is not taken care of.
Target crack formation prevention measures
To prevent crack formation in the target, an important consideration is heat dissipation. On the one hand, the water cooling mechanism is used to remove the unnecessary heat energy in the target material, and on the other hand, the power is considered to be increased. Increasing the power in a short period of time will also bring thermal shock to the target. Furthermore, it is recommended to bond these targets to the backing plate, which not only provides support for the targets, but also promotes better heat exchange between the targets and the water. If the target is cracked and supported by a backing plate, it can still be used without problems.
The above are the reasons for the formation of sputtering target cracks, if you have any questions, please send us an inquiry. The experienced team of Xinkang New Materials will provide a satisfactory solution for your project. Xinkang New Materials Co., Ltd. has been a global sputtering target coating manufacturer since 2014. For more information, please visit https://www.xk-sputteringtarget.com/.