Ultrathin Ni(Pt)Si Film Formation Induced By Laser Annealing

With complementary metal-oxide-semiconductor (CMOS) field effect transistor feature size continuously decreasing, silicide contact layers on source/drain and gate regions are also shrinking and thinning. The conventional lamp based two-step rapid thermal process (RTP) is more and more difficult to form these thin silicide layers. Laser spike annealing (LSA) is developing quickly with advantages such as very short annealing time and better thermal budget control. However, many special characteristics of LSA are still required to be explored considering LSA as a higly none equilibrium thermal process. In this paper, the following three parts are studied for Ni(Pt)Si film formation induced by LSA.1. The study of Ni(Pt)Si formation induced by LSA for Ni(Pt) film with various thickness on different kinds of substrates:Manufactured by industry 40nm standard CMOS process, Ni(Pt) films were deposited on different kinds of substrate including P+/N-Si, N+/P-Si, P+Poly, N+Poly, followed by RTP or LSA to form silicide film. By means of four-point probe method, micro-Raman scattering spectroscopy, SEM, AFM, the silicide formation characteristics are studied. The dependence of the optical property and resistivity of the Ni(Pt) film on its thickness is revealed. It was found that with the increasing of the silicide film thickness and the spike temperature for LSA, the sheet resistance of silicides decreases and the NiSi phase can be observed, but it was demonstrated that NiSi formation temperature highly depended on the type of the substrate.2. The study of ultra-thin Ni(Pt)Si film formation induced by LSA:For 50A Ni(Pt) film after single-step LSA, the formed silidie film sheet resistance is lowered and stabilized with a high thermal budget, which is very different from the conventional RTP. It is revealed that LSA at 900℃ (LSA900C) results in the formation of high quality NiSi and the NiSi/Si interface is smooth. While LSA at 700℃ only results in the formation of Ni2Si and NiSi mixture and the silicide/silicon interface is rough. Besides, even for LSA700C over silicidation is still observed at the interface of Si active region/STI. The reasons are discussed.3. The thermal stability study of the silicide induced by LSA:Silicidation based on one step LSA, LSA1+RTP2, RTP1+LSA2 and RTP1+RTP2 was respectively explored1. It is demonstrtated that RTP1+LSA2 results in the best process performance with approximate sheet resistance, NiSi phase and minimized over-silicidation. It is also revealed that a much improved thermal stability is observed for samples with Ni(Pt)Si formation induced by LSA. The reasons are attributed to the stress relief and Pt redistribution after LSA.