Superior etch performance of Ar/N2/F2 for PECVD chamber clean

F₂ gas mixtures offer ideal properties to be employed as chamber cleaning gas: low dissociation energy and high reactivity, which leads to superior efficiency and ease of abatement. In this work, a new F₂ gas mixture was used with a combination ratio of 10% Ar, 20% F₂ and 70% N₂ in order to obtain a maximum of 20% fluorine in inert gases. This novel Ar/N₂/F₂ gas mixture has been evaluated as a candidate to replace conventional cleaning gases, like NF₃, C₂F₆ and CF₄ in an industrial AMAT P5000 CVD chamber tool. Standard equipment has been used, showing complete compatibility with the new gas. The tested Ar/N₂/F₂ mixture shows improvements in both parameters, cleaning at a faster rate (up to more 27%), even requiring a lower amount of gas (minus 96% versus NF₃). The higher etching rate and the lower gas consumption assure a sensible CoO (Cost of Ownership) advantage to any potential user. The superior etch rate performance of the Ar/N₂/F₂ gas mixture was combined with excellent etch non uniformities values, of deg3% (1sigma) on SiO₂ and of deg8% (1sigma) on Si₃N₄, respectively. Also amorphous Silicon (a-Si) was etched completely and uniformly. The particle performance data showing in average just 14 particle adders (0.25 mum), indicating that no significant particle contamination was induced by the process and Ar/N₂/F₂ can be used as a highly clean and efficient etching gas as well as an ideal drop-in replacement for the conventional cleaning gases.