Study on spin-on hardmask for quad-layer application

Quad-layer and tri-layer systems have been widely used as stack integration schemes for fine patterning. Compared to tri-layer system, the quad-layer system includes an additional layer of silicon oxynitride (SiON), which requires higher curing temperature (300~400 °C) for its deposition. However, the quad-layer system has several advantages in patterning process. The quad-layer system is more efficient in reflectivity control including pitch dependency than tri-layer system. Besides, it demonstrates excellent pattern fidelity after etch without wiggling. In this paper, we present the benefits of the quad-layer system, and demonstrate well-defined sub-20 nm patterns obtained with carbon-based spin-on hard mask (C-SOH) at high temperature in quad-layer application by multiple patterning process.