Ultra-thin and conformal epitaxial NiSi_2 film on Si fins by barrier-induced phase modulation (BPM) technique

摘要

In this work, a barrier-induced phase modulation scheme to realize an ultra-thin and conformal epitaxial NiSi2 film for wrapped-around contact beyond the 7 nm technology node, is proposed and experimentally demonstrated. The 1 nm thick Al2O3 barrier inserted between the Ni film and the substrate can limit the amount of nickel diffusing into silicon and establish an initial Si-rich region consisted of only a few atomic layers during a rapid thermal annealing treatment, so that NiSi2 can grow epitaxially as the first phase at a temperature as low as 600 degrees C. Additionally, thanks to the barrier layer, a relatively thick (50 nm) Ni film can be used, which not only ensures the continuity of NiSi2 formed on sidewalls of three-dimensional structures, but also reduces the process complexity. As a result, a conformal 3.3 nm NiSi2 shell with Phi(Bn)=0.33 eV is successfully obtained on Si fins.