Embodiments of the present disclosure describe techniques and configurations for a memory device comprising a memory array having a plurality of wordlines disposed in a memory region of a die. Fill regions may be disposed between respective pairs of adjacent wordlines of the plurality of wordlines. The fill regions may include a first dielectric layer and a second dielectric layer disposed on the first dielectric layer. The first dielectric layer may comprise organic (e.g., carbon-based) spin-on dielectric material (CSOD). The second dielectric layer may comprise a different dielectric material than the first dielectric layer, such as, for example, inorganic dielectric material. Other embodiments may be described and/or claimed.