Recovery of forming gas damaged Pb(Nb, Zr, Ti)O-3 capacitors

We report on the recovery of fully integrated Pb(Nb, Zr, Ti)O-3 ferroelectr ic capacitors damaged during forming gas (4% H-2, balance N-2) annealing. T he capacitors were encapsulated using TiOx and SiO2 as interlevel dielectri cs to prevent any loss of oxygen or lead. Hydrogen, however, diffused into the ferroelectric film leading to the loss of ferroelectricity. To recover the properties of the capacitor, the fully integrated structure was anneale d in N-2 ambient to drive the hydrogen out. Raman scattering experiments pe rformed in the high frequency regime to detect the [OH-] stretching vibrati on mode confirmed the removal of hydrogen after annealing in N-2. The ferro electric properties, including polarization and resistivity of the capacito rs, were restored to their initial values prior to damage. This shows that the process of hydrogen damage is reversible with the time to recovery bein g dependent on the amount of hydrogen in the forming gas. (C) 2000 American Institute of Physics. [S0003-6951(00)03606-8].