Electron-Beam Patterning of the Low-Loss (High-Q) Ferrimagnetic Coordination Compound V[TCNE]_x~2 (Vanadium Tetracyanoethylene)

Integrating patterned, low-loss magnetic materials into silicon-based devices and circuits presents many difficulties, from lattice matching requirements to extreme deposition conditions for traditional ferrite materials. Here we present the deposition, patterning, and characterization of the low-loss (α = 3.94 x 10^-5), room-temperature ferrimagnetic coordination compound vanadium tetracyanoethylene, (V[TCNE]_x~2). Patterning of V[TCNE]_x~2 thin films from 100 nm to 1 µm thick is performed via electron-beam lithographic patterning using a poly(methyl methacrylate), poly(methyl methacrylate-methacrylic acid 8.5%) copolymer bilayer (PMMA/P(MMA-MAA)) on sapphire and silicon, and this process can be trivially extended to most inorganic substrates. The V[TCNE]_x~2 is deposited on the patterned PMMA/P(MMA-MAA) via chemical vapor deposition (CVD) at 30 mTorr and 50°C in an argon atmosphere. V[TCNE]_x~2 patterned in this method retains its low-loss characteristics down to feature sizes of 10s of µm, below which a non-conformal deposition regime leads to a non-trivial geometry. These results establish the versatility and potential of V[TCNE]_x~2 to be incorporated in future silicon-based electronic devices.