Oxide electrodes as barriers to hydrogen damage of Pb(Zr,Ti)O3-based ferroelectric capacitors

Abstract

The ferroelectric properties of Pb(Zr,Ti)O3 films are known to degrade when subjected to forming gas anneals. In an earlier publication we established that although there may be loss of oxygen and lead during forming gas anneal, the primary mechanism for loss of ferroelectricity is the incorporation of hydrogen and subsequent formation of [OH]−1 bonds between the ionized hydrogen and oxygen ions along the polarization axis in the octahedra. In this study, we show that (La,Sr)CoO3 oxide electrodes can act as a diffusion barrier to hydrogen during forming gas anneals. Forming gas anneal at lower temperatures such as 200 and 300 °C does not lead to a measurable loss of polarization. There is some loss of polarization during forming gas anneals at 450 °C for 12 h, however the capacitors still exhibit ferroelectric properties. The capacitors show no fatigue up to 1011 cycles, no imprint, good logic state retention characteristics, and similar slopes for the pulse width dependent polarization values before and after forming gas anneal in the measured range. More importantly, we have demonstrated that even a bare La0.5Sr0.5CoO3 top electrode can prevent the complete loss of ferroelectricity during forming gas treatment.

Analysis of the degradation of BaTiO3 resistivity due to hydrogen ion incorporation: Impedance spectroscopy and diffusion analysis

“…Furthermore, the perovskite oxides (ABO 3 ) coated on a silicon wafer should be annealed at 450°C in the reductive atmosphere, containing hydrogen gas, to prevent SiO 2 formation at the interface [8]. One concern is that hydrogen ions may diffuse to the perovskite layer and degrade its resistivity [9].…”

The Effect of Hydrogen on the Fracture Properties of 0.8(Na1/2Bi1/2)TiO3-0.2(K1/2Bi1/2)TiO3 Ferroelectric Ceramics

“…[1][2][3][4][5][6][7][8][9][10][11] Moreover, hydrogen also affects the mechanical properties of ferroelectric ceramics. Hydrogen fissures initiate and grow along grain boundaries in PZT ceramics during hydrogen charging in a solution under load-free conditions once the hydrogen concentration in the sample exceeds a critical value.…”

Effect of humidity and hydrogen on the promotion of indentation crack growth in lead-free ferroelectric ceramics

“…Hydrogen, which enters ferroelectric ceramics during gas formation or in the electroplating process, can induce severe degradation of physical properties including an increase in the leakage current, a reduction of the remnant polarization and degradation of polarization hysteresis characteristics [11][12][13][14][15][16][17][18]. Hydrogen-induced cracking (HIC) of an alumina ceramic during dynamical charging with various current densities were investigated using constant load specimens [19].…”