Effects of Capping Electrode on Ferroelectric Properties of Hf0.5Zr0.5O2 Thin Films

In this letter, effects of top electrodes (TEs) on ferroelectric properties of Hf-0.5 Zr-0.5 O-2 (HZO) thin films are examined systematically. The remnant polarization (P-r) of HZO thin films increases by altering TEs with lower thermal expansions coefficient (alpha). The largest 2P(r) value of 38.72 mu C/cm(2) is observed for W TE with alpha = 4.5 x 10(-6)/K, while the 2P(r) value is only 22.83 mu C/cm(2) for Au TE with alpha = 14.2x10(-6)/K. Meanwhile, coercivefield (E-c) shifts along the electric field axis and the offset is found to be dependent on the difference of workfunctions (WFs) between TE and TiN bottom electrode (BE). E-c shifts toward negative/positive direction, when theWF of TE is larger/smaller (Pt, Pd, Au/W, Al, Ta) than TiN BE. This letter provides an effective way to modulate HfO2-based device performance for different requirements in actual application.