Keywords: LaOx, lanthanum oxide, metal gate NMOSFET, flat–band voltage rolling off, ALD, EOT, capping layer, EMF, 28 nm CMOS technology, modelling, flat–band roll–off behaviour, capping layers, high–K gated NMOSFET, nanotechnology
Modelling and characterisation of flat–band roll–off behaviours in LaOx capped high–K/metal–gate NMOSFET with 28 nm CMOS technology
In this paper, we model and characterise the lanthanum oxide (LaOx) capping layer induced flat–band voltage (VFB) roll–off behaviours in a high–K/metal–gate n–MOSFET prepared with a foundry's state of the art 28 nm CMOS technology. As the interface layer EOT down to 1 nm, the VFB rolling–off caused by the 10 cycles (∼5 Å) and 20 cycles (∼10 Å) ALD LaOx capping layers are high, up to ∼282–mV and 550–mV, respectively. The significant VFB rolling–off behaviours were investigated by the measurements of gate C/V, gate I/V and VFB vs. EOT. The phenomena were modelled and explained comprehensively with a schematic diagram.