High-k lithium phosphorous oxynitride thin films

Lithium phosphorous oxynitride (Lipon) thin films have been fabricated onto $n-Si$ substrate at room temperature by nitrogen plasma-assisted deposition of electron-beam reactive evaporated $Li3PO4.$ The capacitance–voltage $(C–V)$ and $I–V$ characteristics of Al/Lipon/Si capacitors were measured. The accumulation, depletion, and inversion phenomena in the $C–V$ curves of the as-deposited Lipon thin film could be clearly observed. The isothermal transient ionic current of Al/Lipon/Al as a function of time during voltage stepping from 0 to 3 V exhibits a large current response due to dipole orientation. The dielectric constant of Lipon thin films is found to be 16.6, and the leakage current density at an applied electric field of 5 kV/cm is about $6.0×10−7 A/cm2.$ These results suggest that lithium phosphorous oxynitride thin films are high-$k$ materials. The incorporation of N into amorphous of $Li3PO4$ could significantly increase the dielectric constant of Lipon thin films.