Highly selective etch of silicon dioxide with tungsten hard mask deposited by PVD process

摘要

The tungsten (W) film deposited by physical vapor deposition (PVD) is a option of hard mask on SiO₂ film for nano-patterning. To enhance deep etching of SiO₂, hard masks are widely used for its high selectivity. We studied different parameters in SiO₂ reactive ion etch (RIE) process such as power, gas chemistries (CHF₃/Ar/O₂) and pressure that influence the selectivity of SiO₂/W. It is revealed that with the increase of RF power, the etching rate of SiO₂ and the selectivity increase continually. With the increase of work pressure, the selectivity decreases greatly. Ar and O₂ play important roles in the process. And a selectivity of SiO₂ film to W hard mask of 78:1 is realized in this work, which shows great potential of W as a hard mask in application.