Disclosed are approaches for 3D NAND structure fabrication. One method may include providing a stack of layers comprising a first and second plurality of layers, and forming a plurality of trenches in the stack of layers, wherein each of the trenches includes a tiered sidewall. A first trench may be formed to a first depth, and a second trench may be formed to a second depth, which is greater than the first depth. The method may further include forming a liner within the trenches, wherein the liner is deposited at a non-zero angle of inclination relative to a normal extending perpendicular from the top surface of the stack of layers. The liner may have a first thickness along the tiered sidewall of the first trench and a second thickness along the tiered sidewall of the second trench, wherein the first thickness is greater than the second thickness.