Linear Fine-Tuning VFB and Improved Interface via Novel Al₂O₃ Atomic in-situ Dipole Buffer Layer (DBL) in ALD La₂O₃ Dipole-First Stack

In this letter, a novel Al2O3 atomic in-situ dipole buffer layer (DBL) technique is proposed for achieving VFB linear fine-tunability and interface improvement in La2O3 dipole-first gate stack. 10 VFB levels with minimum 9 mV linear fine-tuning step in 400 mV range are achieved by manipulating sub-5-Å Al2O3 between SiO2 interfacial layer (IL) and La2O3 dipole layer in metal-oxide-semiconductor capacitors (MOSCAPs). Furthermore, the Si/SiO2 interface is improved with more than 60.3% interface trap density (Dit) decrease by suppressing La-Si interdiffusion with Al-DBL. A mechanism of La-dipole fine-tuning is proposed and indicates that the Al-DBL is one of the promising techniques for multi-VT integration in future NS GAA-FETs.