p-Type Oxide Thin-Film Transistor with Unprecedented Hole Field-Effect Mobility for an All-Oxide CMOS CFET-like Inverter Suitable for Monolithic 3D Integration

Abstract

The lack of low temperature processable, high-performance p-type oxide thin-film transistors (TFTs) limits their implementation in monolithically integrated back-end-of-line (BEOL) CMOS circuitries. In this work, we demonstrate a reactive magnetron-sputtered SnO_<i>x</i> TFT with unprecedented hole field-effect mobility (μ_{<i>FE-hole</i>}) of 38.7 cm²/V·s, as well as an on/off current ratio (<i>I</i>_{<i>on/off</i>}) of 2.5 × 10³ and lower subthreshold swing (SS) of 240.9 mV/dec when compared to reported works on p-type oxide-based TFTs. Material characterization correlated with the SnO_<i>x</i> TFTs' electrical behavior elucidated the performance to the structural and compositional phase modulation of the SnO_<i>x</i> thin films, modulated by O₂ partial pressure during deposition and post-encapsulation annealing. By integrating the SnO_<i>x</i> TFT with an IGZO TFT in both planar and stacked complementary FET-like form, we demonstrated a true oxide-based CMOS inverter, achieving one of the highest voltage gains of 57 and the lowest static power consumption down to 34 pW for both on and off states.