TaN(x) thin films deposited through various flow ratios of N(2)/Ar for copper barrier properties

Abstract

To optimize copper diffusion barriers, TaN(x) thin films for diffusion barriers were prepared by using radio frequency sputtering with various flow ratios of N(2)/Ar as the reactive gas. The component transformed from Ta(2)N to TaN as observed from deposition rates, and N/Ta ratios as N(2)/Ar flow ratios from 0.075 to 0.3. Furthermore, the structural transformations from body- centered cubic through face- centered cubic to nanocrystalline for TaN(x) thin film demonstrated under increase of N2/Ar flow rate, induced three- step stages for formation of TaN(x) films in the sputtering process. The thermal stabilities of the TaN(x) thin film in Cu/TaN(x)/n(+) np(+) diodes suggest that increasing flow ratio of N(2)/Ar from 0.075 to 0.3 enhanced the thermal stabilities from 450 to 550 degrees C under leakage current conditions below 3 mu A. The observation deduces that N2/Ar flow ratios dominated predominantly properties of TaN(x) films through crystal structure for barrier. c 2008 The Electrochemical Society.