Improvement in electrical properties of high-κ film on Ge substrate by an improved stress relieved pre-oxide method

High-κ/Ge gate stack has recently attracted a great deal of attention as a potential candidate to replace planar silicon transistors for sub-22 generation. However, the desorption and volatilization of GeO hamper the development of Ge-based devices. To cope with this challenge, various techniques have been proposed to improve the high-κ/Ge interface. However, these techniques have not been developed perfectly yet to control the interface. Therefore, in this paper, we propose an improved stress relieved pre-oxide (SRPO) method to improve the thermodynamic stability of the high-κ/Ge interface. The x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) results indicate that the GeO volatilization of the high-κ/Ge gate stack is efficiently suppressed after 500 °C annealing, and the electrical characteristics are greatly improved. (paper)