Microwave Plasma Assisted Aerosol Deposition (μ-PAD) for Ceramic Coating Applications

To improve plasma and chemical resistance on various vacuum components used for semiconductor manufacturing equipment, various ceramic coating techniques have been applied. Among these methods for ceramic coating, the well-known atmospheric plasma spray (APS) is advantageous for providing thick film (100 µm or more) deposition. However, there are problems associated with the phase transition of the coating film and poor film quality due to formation of voids. To solve these problems, the aerosol deposition (AD) method has been developed. This method provides nice ceramic film quality. However, the coating rate is quite slow and has difficulty producing thick films (>30 µm). To overcome these limitations, microwave plasma-assisted aerosol deposition (μ-PAD) is applied at low vacuum conditions without the AD nozzle. This method uses a microwave plasma source during the AD process. After enduring a long-term durability test, as a trial run, μ-PAD has been applied on the actual process site. With the Al2O3 powder, μ-PAD shows a coating rate that is 12 times higher than the AD method. In addition, the formation of a thicker film (96 µm) deposition has been demonstrated. On the other hand, the coating film hardness, porosity, adhesion, and withstand voltage characteristics were confirmed to be less than the AD method.