Reducing Thicknesses of PbZrₓTi₁₋ₓO₃ Films in Capacitors

A document describes experiments performed to determine effects of reducing the thicknesses of films of lead zirconate titanate (PbZrxTi1-xO3, wherein 0<x<1) used as ferroelectric dielectric layers in some capacitors. The fabrication of specimen capacitors for the experiments involved numerous steps, including spin-coating of PbZrxTi1-xO3-precursor sol-gel solutions onto bottom Pt electrode layers on silicon substrates, heat treatments to covert the sol-gel coats to PbZrxTi1-xO3, and deposition of top Pt electrode layers on the PbZrxTi1-xO3 layers. Various spin rates and solution compositions were used to obtain various PbZrxTi1-xO3- film thicknesses and compositions. Current responses of specimens to applied voltage waveforms were measured to characterize the specimens in terms of capacitance, hysteresis, and polarization. It was concluded that thicknesses of PbZrxTi1-xO3 films could be reduced to between 1,800 and 2,200 A while retaining ferroelectric performance adequate for a proposed development in which nanoelectromechanical switches containing PbZrxTi1-xO3 films would be integrated with complementary metal oxide/semiconductor transistors. One of the sol-gel solutions, characterized by x = 0.45 and a molarity of 0.367, was found to be the most promising for further work to improve performance at thicknesses < 1,800 A.