Improved electrical and interfacial performance of HfO2-based gate stack on Si with Ga2O3-induced dipole dominated effect via laser spike annealing

In this work, metal–oxide–semiconductor (MOS) capacitors with a HfO2/Ga2O3/SiO2/p-Si structure were fabricated and treated with laser spike annealing (LSA) at 650, 850, and 1050 °C in order to investigate the effects on the electrical and interfacial performance of the devices. The p-type dipole dominated effect is demonstrated, although a fixed-charge contribution cannot be fully excluded. The Ga2O3 layer introduces a p-type dipole at the interface, resulting in a 1.03 V flatband voltage (VFB) shift with only a minor increase in equivalent oxide thickness. LSA can further strengthen this dipole dominated effect while improving the gate-stack quality by reducing the trap/detrap electron density (Not) and the interface trap density (Dit) at the same time. The time zero dielectric breakdown test indicates 850 °C as the optimal LSA temperature, yielding the highest breakdown voltage and operational stability. The physical mechanism is directly validated by x-ray photoelectron spectroscopy, which correlates the VFB modulation with a systematic shift in the valence band offset. Our work indicates that the synergistic integration of a Ga2O3 dipole layer with LSA provides a promising strategy for large VFB adjustment and reliability enhancement in advanced MOS technologies.