Effect of La Spatial Uniformity on Ferroelectric Properties of HfO2 Films Deposited by Atomic Layer Deposition Method

Abstract

In this study, the effect of supercycle scheme for La‐doping in HfO2 films by atomic layer deposition (ALD) on their ferroelectric properties is investigated along with the variation of La distribution in HfO2 films. La is doped into HfO2 films by two ALD supercycle methods: metal‐oxidant‐dopant‐oxide (MODO) and metal‐dopant‐oxidant (MDO). Secondary ion mass spectrometry analys is shows that the MDO supercycle method results in a uniform distribution of La in the depth direction, while the MODO supercycle method results in depth‐dependent segregation of La in the HfO2 film. For similar La concentrations, HfO2 films doped with La by the MDO supercycle show a higher percentage of orthorhombic phase with higher oxygen vacancy concentrations than films by the MODO supercycle. For 3% La, the HfO2 film by MDO shows a remanent polarization (2Pr) of ≈31 μC cm−2 at ± 4 MV cm−1, which is twice as large as the remanent polarization of 15 μC cm−2 for the HfO2 film by MODO. In addition, the La‐doped HfO2 film by MDO with a larger fraction of orthorhombic phase shows a smaller wake‐up effect than the La‐doped HfO2 film by MODO.