Disclosed are 3-D DRAM devices and methods of forming 3-D DRAM devices. One method may include forming a stack of DRAM device layers, forming a MOS substrate directly atop the stack of alternating DRAM device layers, and forming a trench through the MOS substrate and the stack of DRAM device layers. The method may further include depositing a protection layer over the MOS substrate, wherein the protection layer is deposited at a non-zero angle of inclination relative to a vertical extending from a top surface of the MOS substrate.