Progress of Microstructure and Texture of High Purity Tantalum Sputtering Target

In recent years, the IC (integrated circuit) industry has developed rapidly and the chip process technology has developed in the direction of higher density. Because of its good chemical stability, tantalum is used as a sputtering coating material for the diffusion barrier in the copper interconnect process. The uniform microstructure of the tantalum target directly affects the sputtering performance. The fabrication of high-quality thin films requires the tantalum target to have fine and uniform crystal grains and random grain orientation distribution. However, due to the characteristics of tantalum, it is easy to form a microstructure with {100} (<100>//ND) orientation on the surface and {111} (<111>//ND) orientation on the core during cold working. During the fabrication of thin films, the sputtering rate varies with the thickness of the target, which affects the sputtering stability. To provide ideas for improving the uniformity of the microstructure of the tantalum target, this article reviews the preparation processes that affect the grain orientation and size of the high-purity tantalum target, including forging methods, rolling methods, recrystallization annealing, etc., analyze the law of texture evolution of tantalum and introduction the research status of cold working and recrystallization.