ToF-SIMS profiling of HfO2/Si stacks: influence of sputtering condition of profile shape

Due to its numerous advantages ToF-SIMS profiling has often been used in the analysis of high-k dielectrics. However, profiling high-k gate stacks induces a number of artifacts such as preferential sputtering, tailing of the metal peak in the substrate, interfacial peaks, etc. In this work, we investigated a number of sputtering conditions (Ar, Xe, Ga, energy ranging from 350 eV to 15 keV) in order to determine the most favorable sputtering condition which minimizes these artifacts. The results show that the tail of the Hf in the Si is only marginally dependent on the sputtering conditions suggesting another mechanism than collisional mixing. It also shows that even if the influence on the tail is limited, Xe profiling is far superior to Ar profiling in terms of depth resolution for the rest of the profile. Finally, this work also shows that partially oxidizing sputtering conditions lead to heavily distorted profiles. # 2004 Elsevier B.V. All rights reserved.