Embodiments described herein generally relate to methods of manufacturing an oxide/polysilicon (OP) stack of a 3D memory cell for memory devices, such as NAND devices. The methods generally include treatment of the oxide and/or polysilicon materials with precursors during PECVD processes to lower the dielectric constant of the oxide and reduce the resistivity of the polysilicon. In one embodiment, the oxide material is treated with octamethylcyclotetrasiloxane (OMCTS) precursor. In another embodiment, germane (GeH4) is introduced to a PECVD process to form SixGe(1-x) films with dopant. In yet another embodiment, a plasma treatment process is used to nitridate the interface between layers of the OP stack. The precursors and plasma treatment may be used alone or in any combination to produce OP stacks with low dielectric constant oxide and low resistivity polysilicon.