The disclosed technology generally relates to memory devices, and more particularly to memory devices having an intergate dielectric stack comprising multiple high k dielectric materials. In one aspect, a planar non-volatile memory device comprises a hybrid floating gate structure separated from an inter-gate dielectric structure by a first interfacial layer which is designed to be electrically transparent so as not to affect the program saturation of the device. The inter-gate structure comprises a stack of three layers having a high-k/low-k/high-k configuration and the interfacial layer has a higher k-value than its adjacent high-k layer in the inter-gate dielectric structure. A method of making such a non-volatile memory device is also described.