Comprehensive Investigation On Cf4/O-2-Plasma Treating The Interfaces Of Stacked Gate Dielectric In Mos2 Transistors

CF4/O-2-plasma is used to treat the interfaces of gate stacks (MoS2/Al2O3/ZrO2/p(+)-Si), and its effects on the electrical performance of the few-layered MoS 2 transistors have been investigated. Experimental results show that excellent electrical properties have been achieved for the MoS2 transistors with CF4/O-2-plasma treated stacked gate dielectric, especially for the F-treated ZrO2 device: high mobility of 53.7 cm(2)/Vs, small subthreshold swing of 117 mV/dec and high on/off ratio of 2.7 x 10(7). The involved main mechanisms lie in the facts that: (i) the MoS2/dielectric interface is improved through the F- passivation on the oxygen vacancies in the dielectric, decreasing the dangling bonds and surface roughness of the dielectric; (ii) the dielectric constant (k) of the gate stack dielectric is increased because of suppressed growth of low-k Zr-silicate interlayer and improved dielectric quality by forming Zr-F and Al-F bonds; (iii) CF4/O-2-plasma treatment on the Zr0 2 surface can result in F incorporation in both ZrO2 and Al2O3, thus giving the best passivation effects on oxygen vacancies and oxide traps near/at the MoS2/dielectric interface. These results indicate that CF4/O-2-plasma treatment is an effective way for improving the bulk and interface qualities of gate dielectrics and thus the electrical properties of MoS2 FETs.