Zinc-oxide (ZnO) and zirconia (ZrO2) metal oxides have been studied extensively in the past few decades with several potential applications including memory devices. In this work, a scalability study, based on the ITRS roadmap, is conducted on memory devices with ZnO and ZrO2 nano-islands charge trapping layer. Both nano-islands are deposited using atomic layer deposition (ALD), however, the different sizes, distribution and properties of the materials result in different memory performance. The results show that at the 32-nm node charge trapping memory with 127 ZrO2 nano-islands can provide a 9.4 V memory window. However, with ZnO only 31 nano-islands can provide a window of 2.5 V. The results indicate that ZrO2 nano-islands are more promising than ZnO in scaled down devices due to their higher density, higher-k, and absence of quantum confinement effects.