Pb(Zr,Ti)O3-silicon heterostructures fabricated by direct wafer bonding

Abstract

Pb(Zr, Ti)O3(PZT)-Silicon heterostructures were fabricated by employing the direct wafer bonding method. PZT thin films were deposited on 3 in. Pt-coated Si wafers by chemical solution deposition (CSD). The PZT films were crystallized by a rapid thermal annealing at 700°C for 60 s and characterized by measuring their ferroelectric properties. The thin films were polished by chemical-mechanical polishing (CMP) and then bonded to plain silicon wafers using a micro-cleanroom setup. The room temperature bonded wafers were annealed for 12 hours at temperatures ranging from 200°C to 450°C. The bonding energy increases from 100 mJ/cm2 after room temperature bonding to 1.4 J/cm2 after a 450°C annealing. Metal-ferroelectric-silicon (MFS) structures were obtained by thinning down and etching away the Pt-coated Si wafer. The MFS structures were electrically characterized by capacitance-voltage and current-voltage characteristic measurements.