Improvement of ferroelectric random access memory manufacturing margin by employing Pt/AlOx bottom electrode for the La-doped Pb(Zr,Ti)O3 ferroelectric capacitor

Abstract

In our previous works on La-doped Pb(Zr,Ti)O3 (PLZT) growth on a Pt/Ti bottom electrode, the O2 content in postdeposition annealing (PDA) was found to play an important role in obtaining good electrical characteristics and high manufacturing yield of ferroelectric random access memory (FeRAM). The optimal O2 content of around 2% inhibits the growth of randomly oriented La-doped Pb(Zr,Ti)O3 (PLZT) grains near the PLZT surface, resulting in the growth of highly {111}-oriented PLZT. We found that the Pt bottom electrode grown on an AlOx layer can further suppress the formation of randomly oriented PLZT grains near the PLZT surface and increases the optimal O2 content range from 2 to 50%, which can enlarge the manufacturing process margin of PDA. It is proven that the AlOx layer blocks the diffusion of lead oxides (PbOx) from PLZT to SiO2 interlayers through Pt and promotes pyrochlore-perovskite transformation near the bottom electrode during PDA.