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

The tungsten (W) film deposited by physical vapor deposition (PVD) is a option of hard mask on SiO
2
film for nano-patterning. To enhance deep etching of SiO
2
, hard masks are widely used for its high selectivity. We studied different parameters in SiO
2
reactive ion etch (RIE) process such as power, gas chemistries (CHF
3
/Ar/O
2
) and pressure that influence the selectivity of SiO
2
/W. It is revealed that with the increase of RF power, the etching rate of SiO
2
and the selectivity increase continually. With the increase of work pressure, the selectivity decreases greatly. Ar and O
2
play important roles in the process. And a selectivity of SiO
2
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.