Low Dielectric Loss Tangent, Highly Scandium Doped Aluminum Nitride Thin Film for Acoustic Devices

The lowest dielectric loss tangent (tanδ) reported so far for a scandium-doped aluminum nitride film with 40 % scandium atomic content (Sc
0.4
Al
0.6
N) was realized on a molybdenum electrode. The dielectric loss tangent was reduced down to 0.07 %, about one fourth of previously reported tanδ [1], using an annealing process.In addition, this low tanδ was applied to a piezoelectric microphone as an acoustic device, its noise level reached - 108 dBV(A), under one half of commercial piezoelectric microphones [2].