Study of Tungsten-Doped Carbon Hard Mask Etch Process Using NF3/O2 Based Chemistry

Tungsten-doped carbon (WDC) materials have been investigated as a hard mask material because of high etching resistance in via and contact holes manufacture integration. This article studied the etching process of WDC in O
2
based plasma with an added reactant source such as Cl
2
or NF
3
chemistry. A series of orthogonal design of experiment (DOE) was utilized to analyze the etch rate data. The results showed that the NF
3
addition can significantly enhance WDC etch rate, compared to Cl
2
addition. The etch selectivity of WDC to silicon oxide (SiO
2
) mask is increased as using synchronic pulsed RF powers, adding BCl
3
and reducing ESC temperature.