Effect of fabrication processes before atomic layer deposition on β-Ga2O3/HfO2/Cr/Au metal–oxide–semiconductor capacitors.

As β-Ga₂O₃ becomes a popular semiconductor material for high-power electronic devices, researchers are presenting innovative device structures and fabrication processes to achieve high performance and enhanced reliability of these devices. In many cases, these fabrication processes involve the formation of mesas, trenches, and other structures by plasma etching of β-Ga₂O₃ with Cl₂ and/or BCl₃. This paper looks at the effects of photoresist patterning and BCl₃ plasma etching prior to atomic layer deposition of HfO₂ dielectric to form metal–oxide–semiconductor capacitors. The β-Ga₂O₃/HfO₂ interface is critical for controlling device characteristics such as flat-band voltage and maximum capacitance under accumulation and can be greatly affected by roughness and chemical residues. Capacitance-voltage data and atomic force microscope (AFM) scans indicate that photoresist and BCl₃ residues are not adequately removed with acetone/IPA/DIW cleaning but are removed using piranha (H₂O₂/H₂SO₄) cleaning before deposition of the dielectric. [ABSTRACT FROM AUTHOR]