The use of thin capping layers that are inserted between the gate metal and dielectric layers have been shown to simultaneously cause a negative flatband voltage (Vfb) shift and to stabilize low threshold voltage (V TH). A major challenge with capping layers is to achieve adequate effective work function shifts without large increases in equivalent oxide thickness (EOT) (EOT). In this work, the effects of La2O3 cap layers prepared by different ALD Lanthanum precursors, La(fAMD)3 and La(thd)3, on flatband voltage tuning and EOT scaling in TiN/HfO2/"SiO"2/Si metal oxide semiconductor (MOS) structures was investigated. Experimental results showed that V fb and EOT as high as 0.45 V and 0.055 nm, caused by dipoles at the lower interface between HfO2 and "SiO"2 interlayer and the diffusion of La and Hf atoms to the "SiO" 2 interlayer, were achieved by a 1 nm thick La2O 3 capping layer using a La(fAMD)3 precursor, while a relatively smaller Vfb and EOT of -0.7 V and 1.27 nm were obtained from the noncap TiN/HfO2/"SiO"2/Si MOSCAP sample. The use of a La(fAMD)3 precursor for the La2O 3 capping layer deposition has been shown being much superior to La(thd)3 due to lower atomic layer deposition (ALD) process temperature and shorter O3 oxidant pulse duration.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry