4-312 The thermal effects of platinum bottom electrodes on PZT sputtered thin films used in MEMS devices A. Koochekzadeh 1,2 , E. Keshavarz Alamdari 1,2 , A.G. Barzegar 3 , G. Rezazadeh 4 1 Materials and Energy Research Center (MERC), P.O.Box. 14155-4777, Tehran, Iran 2 Department of Mining and Metallurgical engineering, Amirkabir University of Technology P.O.Box.15875-4413, Tehran, Iran 3 Department of Material Science, Shiraz University, Shiraz, Iran 4 Department of Mechanical Engineering, University of Urmia, Urmia, Iran E-mail add: A.koochak@gmail.com alamdari@aut.ac.ir barzegar@shirazu.ac.ir g.rezazadeh@mail.urmia.ac.ir Abstract For the achievement of MEMS devices such as microactuators and microsensors based on piezoelectric thin films a Si/Ti/Pt bottom electrode is widely used. This paper shows temperature dependent of surface morphology of both platinum bottom electrode and piezoelectric Lead titanate zirconate (PZT) thin films. Ti (10nm) and Pt (100nm) thin films have been deposited on silicon substrate by thermal evaporation and electron beam respectively without vacuum breaking. After annealing treatment, the Pt film exhibited (111) preferred orientation. Finally a 0.8 micron thick PZT (54/46) film were deposited by r.f. magnetron sputtering at room temperature in pure Ar followed by a conventional post annealing treatment on silicon substrate. The XRD measurements have shown the provskite structure of PZT films with (100) preferred orientation growth. The roughness of platinum film measured by AFM test shows the continues smooth of platinum surface for different annealing temperatures. The SEM test results demonstrate that whatever the annealing temperature increases, recrystallization of platinum and nano-size holes on Pt surface occures. The latter causes to accelerate of out-diffusion titanium atoms through Pt layer and reach to the other side of surface. The surface state of Pt thin film is very important as it can strongly influence the PZT surface morphology so the existence of bubbles and depression on PZT surface are increased with both recrystallization of Pt grains and nano-size holes on Pt film surface when the annealing temperature increased. Keywords: MEMS, PZT, Diffusion, Annealing treatment 1. Introduction The ceramic lead zirconate titanate Pb(Zr x ,Ti 1-x )O3 (PZT) films near the morphotropic phase boundary fabricated by RF magnetron sputtering ,are successfully integrated into silicon-based microelectromechanical systems (MEMS), especially for application in microsensors and actuators [1]. One of the most important problems is the bottom electrode material and its influence on the PZT properties. Platinium layer is the most widely chosen bottom electrode for Si-based devices because of its high thermal conductivity, good stability in oxidizing atmospheres, its relatively low crystallisation temperature and its lattice parameter that is close to that of PZT [2, 3]. The Ti layer is necessary to promote the adhesion of Pt to underlying Silicon but unfortunately the diffusion of Ti atoms through Pt layer during the annealing treatment and reach to the other side of surface occurred and cause to formation of Titanium oxide TiO x [3] so the annealing temperature must be carefully controlled. After deposition of sputtered PZT on bottom electrode, a post annealing treatment is necessary to transform the phase of PZT from amorphous to perovskite. The bubbles and hillocks occures