Improvement of interfacial layer reliability by incorporation of deuterium into HfAlOx formed by D2O-ALD

Deuterium was incorporated into the HfAlOx /SiON gate dielectric by the use of heavy water (D₂O) instead of H₂O in the atomic layer deposition (ALD) process of HfAlOx. The HfAlOx formed by D₂O-ALD acts as a deuterium reservoir, and the deuterium atoms are effectively incorporated into the SiON after full CMOS processing. It is clarified that the deuterium incorporation suppresses interfacial trap generation and interfacial SiON breakdown, while charge-trapping in the HfAlOx bulk traps is barely affected. The D₂O-ALD process is useful for improving the interfacial layer reliability under gate negative stress; therefore it is not only effective for HfAlOx, but also for high-κ/SiO₂(SiON) gate stacks with other high-κ materials such as HfO₂ or HfSiON.