Ferroelectric integrated circuit devices, such as memory devices, are formed on an integrated circuit substrate. Ferroelectric capacitor(s) are on the integrated circuit substrate and a further structure on the integrated circuit substrate overlies at least a part of the ferroelectric capacitor(s). The further structure includes at least one layer providing a barrier to oxygen flow to the ferroelectric capacitor(s). An oxygen penetration path contacting the ferroelectric capacitor(s) is interposed between the ferroelectric capacitor(s) and the further structure. The layer providing a barrier to oxygen flow may be an encapsulated barrier layer. Methods for forming ferroelectric integrated circuit devices, such as memory devices, are also provided.