Plasma-enhanced atomic-layer deposition of a HfO2 gate dielectric

Hafnium oxide (HfO2) films deposited by using both the conventional atomic-layer deposition (ALD) and the plasma-enhanced ALD (PEALD) techniques using Hf(NEt2)(4) were investigated as a potential replacement for SiO2 gate dielectrics. HfO2 films deposited with oxygen plasma showed lower impurity contents than those of films deposited with oxygen gas. HfO2 films showed a randomly oriented polycrystalline structure with the relatively smooth amorphous characteristics of an interfacial layer. The interfacial layer of the HfO2 films deposited with oxygen plasma showed silicate (or SiOx) characteristics. HfO2 films showed almost negligible hysteresis with a positive flat band shift. They also showed a leakage current of about similar to10(-9) A/cm(2). Post annealing significantly changed the characteristic of the HfO2 films. HfO2 films deposited with oxygen plasma showed generally improved film qualities compared to the films deposited with oxygen gas.