Amazing diffusion depth of ultra-thin hafnium oxide film grown on n-type silicon by lower temperature atomic layer deposition

• Published in: Materials letters 2016-04, Vol.169, p.164-167
• Main Authors: Lu, Qihai, Huang, Rong, Lan, Xiaoling, Chi, Xiaowei, Lu, Chao, Li, Cheng, Wu, Zhiguo, Li, Jun, Han, Genliang, Yan, Pengxun
• Format: Article
• Language: English
• Subjects: Deposition; Diffusion; Diffusion depth; Diffusion layers; Hafnium; Hafnium oxide; Hafnium silicate; Hafnium silicide; HfO2; Silicides; Silicon; Tunnel contact; X-ray photoelectron spectroscopy
• ISSN: 0167-577X; 1873-4979
• DOI: 10.1016/j.matlet.2016.01.087

Hafnium diffusion from ultra-thin high-k gate dielectric HfO2 deposited on n+-Si substrate by atomic layer deposition at lower temperature of 150°C was investigated by using x-ray photoelectron energy spectra (XPS) analysis. The surface is the complete oxidation of HfO2, and Hf and O diffusion into Si substrate with different depths during atomic layer deposition process. Hf and O incorporation into silicon forms silicates accompany with silicides and further silicides only, respectively. An empirical formula was deduced to calculate the diffusion depth of the Hf element to 33nm. The Ni80Fe20/HfO2/Si contact resistance was dominated by tunneling current for the thicker HfO2 but limited by Schottky barrier height for the thinner HfO2 by setting 1.5nm as a watershed. [Display omitted] •Hf and O of HfO2 films spread into silicon forming silicates and further silicides.•An empirical formula was deduced to calculate the diffusion depth of Hf into Si to about 33nm.•The NiFe/HfO2/Si contact resistance was mutational by setting 1.5nm as a watershed.