Pulsed laser deposition of piezoelectric lead zirconate titanate thin films maintaining a post-CMOS compatible thermal budget

Abstract

Integration of lead zirconate titanate (Pb[Zrx,Ti1-x]O3 – PZT) thin films on complementary metal-oxide semiconductor substrates (CMOS) is difficult due to the usually high crystallization temperature of the piezoelectric perovskite PZT phase, which harms the CMOS circuits. In this work, a wafer-scale pulsed laser deposition tool was used to grow 1 μm thick PZT thin films on 150 mm diameter silicon wafers. Three different routes towards a post-CMOS compatible deposition process were investigated, maintaining a post-CMOS compatible thermal budget limit of 445 °C for 1 h (or 420 °C for 6 h). By crystallizing the perovskite LaNiO3 seed layer at 445 °C, the PZT deposition temperature can be lowered to below 400 °C, yielding a transverse piezoelectric coefficient e31,f of −9.3 C/m2. With the same procedure, applying a slightly higher PZT deposition temperature of 420 °C, an e31,f of −10.3 C/m2 can be reached. The low leakage current density of below 3 × 10−6 A/cm2 at 200 kV/cm allows for application of the post-CMOS compatible PZT thin films in low power micro-electro-mechanical-systems actuators.