Extraction of Cu diffusivities in dielectric materials by numerical calculation and capacitance-voltage measurement

A rigorous method of obtaining the Cu diffusivities in various SiO2-based dielectric materials is proposed. The diffusion profile of Cu ions in a dielectric material is first simulated and the resulting flatband voltage shift (ΔVFB) is compared with the experimental results obtained by C-V measurements after bias-temperature stressing (BTS). The evolution of the Cu concentration in dielectric materials is evaluated using a one-dimensional finite differential method with two unknown parameters, the diffusivity, and the maximum solid solubility of Cu ions in the dielectric material. C-V measurements are conducted at 1MHz to measure the ΔVFB value of Cu∕SiO2∕Si capacitors before and after BTS at an electric field of +1.0MV∕cm and in the temperature range between 200 and 275°C. With this process, the Cu diffusivities in thermally grown SiO2, oxynitride and SiO2 deposited by plasma-enhanced chemical vapor deposition, and methyl-doped SiO2 are found to be 2.22×10−3exp(−1.54eV∕kT), 3.09×10−5exp(−1.34eV∕kT), 2.59×10−5exp(−1.18eV∕kT), and 6.07×10−9exp(−0.71eV∕kT), respectively.