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Keep your chamber clean

: Riva, M.; Pittroff, M.; Schwarze, T.; Oshinowo, J.; Wieland, R.

EuroAsia Semiconductor 30 (2008), Nr.7, S.20-26
ISSN: 1751-1135
ISSN: 0265-6027
Fraunhofer IZM ()

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, C 2F6 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 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 excellen t etch non uniformities values, of ±3% (lsigma) on SiO2 and of ±8% (lsigma) on Si3N4, respectively. Also amorphous Silicon (a-Si) was etched completely and uniformly. The particle performance data showing in average just 14 particle adders (0.25m), indicating that no significant particle contamination was induced by the process and Ar/N 2/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.