Controlling Work Function and Damaging Effects of Sputtered RuO₂ Gate Electrodes by Changing Oxygen Gas Ratio during Sputtering

Abstract

RuO₂ metal gates were fabricated by a reactive sputtering method under different O₂ gas ratios. For the given sputtering power of 60 W, a ∼13% O₂ ratio was the critical level below or over which RuO₂ film has hyperstoichiometric and stoichiometric compositions, which resulted in a difference in the effective work function by ∼0.2 eV. The stoichiometric RuO₂ film imposes almost no damaging effect to the underlying SiO₂ and HfO₂ gate dielectrics. The RuO₂ gate decreased the equivalent oxide thickness by ∼0.5 nm and leakage current by around two orders of magnitude compared to the Pt-gated samples.

Ferroelectric properties and switching endurance of Hf0.5Zr0.5O2 films on TiN bottom and TiN or RuO2 top electrodes

“…The sample, however, showed an even more distorted P – E loop, which might have resulted from the space‐charge layer at the RuO 2 /HZO interface. In fact, the process of TE sputtering is well known as a source of interfacial defects 13. It is surprising to note that an Ru peak can be observed even for the GAXRD spectra of RuO/PDA, meaning that RuO 2 is partly reduced during the sputtering process of RuO 2 even without any thermal treatment.…”

“…The TiN TE samples were annealed at 500 °C for 30 s in a N 2 atmosphere after TE deposition (TiN/PMA). The details of the optimized RuO 2 deposition condition were reported elsewhere 13. For the RuO 2 TE samples, on the other hand, the following three annealing conditions were adopted: (1) postmetallization‐annealing (RuO/PMA) – annealing at 500 °C for 30 s in a N 2 atmosphere after TE deposition; (2) postdeposition‐annealing (RuO/PDA) – annealing at 500 °C for 30 s in a N 2 atmosphere before TE deposition; and (3) PDA + curing (RuO/curing) – annealing the PDA samples at 400 °C for 30 min in an air atmo‐sphere after TE deposition.…”

Activation Energy Distribution of Dynamical Structural Defects in RuO2 Films

“…This theoretical estimate is reasonably close to our peak value of ~0. 8 [50]. Besides, TLSs can generate frequency noise, namely, random fluctuations of the resonance frequency, in a small mechanical resonator.…”

Nonvolatile Random Access Memory and Energy Storage Based on Antiferroelectric Like Hysteresis in ZrO2

“…According to the developed model, atop of the previously discussed ZrO 2 /TiN capacitor stack, a ruthenium oxide (RuO x ) top electrode was deposited by means of PVD. RuO x is a material characterized by a very high work function of 5.3 eV that is about 0.8 eV higher than the work function of the TiN bottom electrode. In this manner, the work function asymmetry introduced into a 10 nm stack resulted in a strong internal bias field in the order of 1 MV cm −1 .…”