ABSTRACT
Scaling of a field effect transistor (FET) has been the major driving force behind the continuous improvements of the silicon-based semiconductor chips for achieving higher packaging density, higher speed, and lower power consumption/dissipation. With the mass scale production technology node reaching 45 nm and below, there was an urgent requirement of oxide thickness of less than 1.2 nm. Such an ultra-thin gate oxide led to direct tunneling resulting in an exponential increase of gate leakage current which was unacceptable due to the huge power consumption [1,2]. So, a hafnium-based high-κ dielectric constant was adopted, which replaced the traditional SiO2 due to its relatively high dielectric constant and wideband gap. But hafnium-based gate dielectric materials posed new problems such as an increase in scattering for carriers, a lower effective mobility, and an increase in the interface-state density [4]. The continuous and aggressive scaling of the transistor further leads to a demand for new and better high-κ gate dielectric stacks to overcome the problem [1,2]. Lathanum incorporated in hafnium seems to be one of the promising new approaches to overcome the issues related to the hafnium-based high-κ dielectric stacks. There are many reports of attempts to incorporate La2O3 into HfO2 film, and improvements in oxide-charge density (Q ox) as well as D it have been reported [4,5].
