Plasma decomposition of ferrocene

Ferrocene [Fe(C5H5)2 or FeCp2] is a well-known precursor molecule for iron in vapor deposition of iron containing films by, e.g., chemical vapor deposition (CVD) processes. CVD processes often use the energy in plasma discharges to decompose precursor molecules, which allows lowering the substrate temperature for deposition on sensitive materials. Herein, we studied the plasma decomposition of ferrocene in a plasma CVD reactor using in situ optical emission spectroscopy and quadrupole mass spectrometry, coupled with in silico quantum chemical modeling. We suggest a plasma chemical decomposition model under medium vacuum conditions where FeCp2 is likely to undergo neutral decomposition, detaching both Cp ligands from the iron center, followed by fragmentation via C2H2- and C3H3 to C2, CH, H2, and H.