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 <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> based plasma with an added reactant source such as Cl <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> or NF <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> chemistry. A series of orthogonal design of experiment (DOE) was utilized to analyze the etch rate data. The results showed that the NF <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> addition can significantly enhance WDC etch rate, compared to Cl <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> addition. The etch selectivity of WDC to silicon oxide (SiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> ) mask is increased as using synchronic pulsed RF powers, adding BCl <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> and reducing ESC temperature.