Highly Robust All-Oxide Transistors with Ultrathin In2O3 as Channel and Thick In2O3 as Metal Gate Towards Vertical Logic and Memory

In this work, we report for the first time atomic-layer-deposited (ALD) all-oxide transistors toward 3-D vertical integration, with thick ALD In2O3 as gate electrodes, and In2O3 itself as contact. The all-oxide thin-film transistors (TFTs) show an on/off ratio over 10⁶, high uniformity, and very robust reliability with a threshold voltage shift ($\Delta \mathrm{V}_{\text{TH}}$) of 5 mV and 50 mV in positive and negative bias stress (PBS and NBS) tests. The vertically all-oxide TFTs demonstrate good control from side wall with on/off ratio over 10⁵ and maximum current ($\mathrm{I}_{\max}$) over $160\ \mu\mathrm{A}/\mu\mathrm{m}$. And vertically all-oxide ferroelectric field-effect transistors (Fe-FETs) exhibit a memory window (MW) of 1.85 V, with an endurance and retention extended to 10¹² cycles and 10 years. This illustrates the vertically all-oxide device based on ALD oxide semiconductor (OS) is a good candidate toward future high-density integrated circuits.