Pulsed laser deposition of multilayer TiN/Pb(Zr xTi 1− x)O 3 for piezoelectric microdevices

Abstract

Multilayer Pb(ZrTi)O 3 (PZT)/TiN/Si structures were grown by two subsequent laser ablation processes in reactive atmosphere. First, a fcc-oriented TiN film was deposited by laser ablation of a Ti target in high-purity nitrogen reactive gas. Subsequently, a crystalline, piezoelectric PZT film was grown by reactive ablation of a PZT target in oxygen atmosphere. Both deposition processes were conducted at quite low Si(100) substrate temperature: 350°C for TiN and 370°C for PZT, in the same experimental setup (Nd-YAG laser, λ=1060 nm, energy/pulse 0.3 J, t FWHM=10 ns). TiN film properties were analyzed by XRD and electric measurements. After the deposition of the PZT layer, the obtained structure was first characterized by XRD, SEM and SIMS techniques. Testing measurements performed after the deposition by thermal evaporation of an Al layer as top electrode on the PZT/TiN/Si structure confirm that they can be used as sensor transducer element. The TiN (as high conductive nitride) layer replaces the former Au layer used as bottom electrode. In this way, the Au diffusion inside the Si substrate, as well as in the deposited layer, is avoided, as could be observed from a comparative study of the SIMS spectra recorded for PZT/TiN/Si and PZT/Au/Si configurations.