Densification of polycrystalline alumina with dense dislocation arrays via stainless steel sealed powder metallurgy hot isostatic press

Aluminum oxide (alumina, Al₂O₃) is one of the most widely used ceramic materials owing to its excellent dielectric, chemical resistance, and low cost. In contemporary semiconductor fabrication processing, in particular, Al₂O₃ plays a key role in high-value processing components, such as an electrostatic chuck. Here, we report for the first time a novel densifying technique for Al₂O₃ that can be referred to as the powder metallurgy hot isostatic press (PM-HIP) process. Unlike the conventional HIP process, our PM-HIP process can directly convert Al₂O₃ powders into fully densified ceramics via a one-step process. More importantly, during the PM-HIP process, thermomechanical energy can easily be transferred to each of the particles simultaneously, which facilitates the sinter process (i.e., necking and diffusion) and the clipping of lattice planes. As a result, highly dense dislocation arrays are embedded within the entire volume of the sintered body. This correlates with unique material properties-processing relationships in the Al₂O₃ ceramics sintered via PM-HIP. The Al₂O₃ ceramics sintered by PM-HIP exhibited unique mechanical and electrical properties, highlighting its potential for use in electrostatic chucks.