Hardmask layer for 3D NAND staircase structure in semiconductor applications

A method of forming a hardmask layer on a substrate comprises:

• forming a seed layer comprising boron on a film stack disposed on a substrate by supplying a seed layer gas mixture in a processing chamber, wherein the seed layer gas mixture comprises at least a boron containing gas and a nitrogen containing gas;
• forming a gradient transition layer comprising boron and tungsten on the seed layer by supplying a transition layer gas mixture in the same processing chamber, wherein the transition layer gas mixture is supplied to the processing chamber by ramping down a gas flow rate of the boron containing gas while maintaining a steady gas flow rate of the nitrogen containing gas to form the transition layer, and gradually ramping up a gas flow rate of a tungsten containing gas in the transition layer gas mixture;
• and
• forming a bulk hardmask layer comprising tungsten on the transition layer by supplying a deposition gas mixture in the same processing chamber, wherein the nitrogen containing gas is continuously supplied at the steady gas flow rate while forming the bulk hardmask layer.