Characterizing high-k and low-k dielectric materials for semiconductors: Progress and challenges

SIMS has been applied to the characterization of high-k and low-k materials used in the semiconductor manufacturing process. Profiles of thin high-k films, particularly HfO2 and HfSiO, exhibit preferential sputtering that affects ion yields and sputter rates in the films as well as in the Si substrate. These artifacts make it difficult to quantify major constituents and dopants in the films and substrate. The ion yields of B were observed to vary by as much as 3 as a function of Si content in HfSiO films, while As ion yield variations are not as great. Evidence for B penetration from a highly-doped Si substrate into the high-k films was also observed and quantified. First generation low-k films are not as susceptible to charging as the newer, porous materials. Backside SIMS was used to show Ti migration into the open pores of a low-k film during the metal deposition step.