Effect of the diamond nucleation process on freestanding AIN/diamond SAW filter characteristics

Abstract

In this work, the effect of diamond nucleation process on freestanding AIN/diamond SAW device performances were studied. Before diamond deposition, silicon substrates were mechanically nucleated, using an ultrasonic vibration table with sub-micron diamond slurry, and bias enhanced nucleated (BEN). Freestanding diamond layers obtained on mechanically scratched Si substrates exhibit a surface roughness of R-MS=13nm whereas very low surface roughness (as low as R(MS)less than or equal to1 nm) can be achieved on BEN diamond layer. Propagation losses (a) and electromechanical coupling coefficient (K-2) have been measured as a function of the operating frequency and the normalized AN film thickness (kh(AlN)=21pih(AIN)/lambda). Experimental results show that the propagation losses strongly depend on nucleation technique while the electromechanical coupling coefficient slightly depends on nucleation technique.