Selective deposition of SiN on horizontal surfaces

Methods and apparatuses for selectively depositing silicon nitride (SiN) via high-density plasma chemical vapor deposition (HDP CVD) to form a SiN pad on an exposed flat surface of a nitride layer in a 3D NAND staircase structure with alternating oxide and nitride layers are provided. In some embodiments, selective etching is performed to remove undesirable buildup of SiN on sidewalls of the oxide layers of the staircase structure. Nitride layers of the staircase structure are replaced with tungsten (W) to form tungsten wordlines, while the SiN pads are replaced with tungsten to from landing pads, which prevent punchthrough of the tungsten wordlines on the staircase structure by interconnects extending thereto.