U-Shaped Sloped Field Plate Edge Termination Structure in β-Ga₂O₃ Vertical SBD

In this work, we developed a β-Ga<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> Vertical Schottky barrier diode (SBD) device with a U-shaped Sloped field plate (U FP) and established its corresponding fabrication process flow. The deep mesa termination with a depth of approximately 5 μm serves as the basis for the entire termination structure. Next, a 100nm-thick Al<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> layer and BCB dielectric were deposited in the trench region. Using the associated "puddle development" technique, arc-shaped pits were fabricated. Subsequently, metal field plates connected to the anode were deposited in these pits to weaken and redistribute the electric field peak at the edge of the mesa termination structure. TCAD simulations demonstrated that the introduction of arc-shaped field plates effectively weakened and redistributed the original electric field peaks. Furthermore, annealing and wet chemical treatment were incorporated into the device fabrication process to address etching-induced defects and mitigate the sharp decline in forward current density post-etching. Currently, we have fabricated devices with an on-resistance of 9.5 mΩꞏcm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and a breakdown voltage of approximately 1.8 kV. This work will provide valuable insights for the development of high-voltage β-Ga<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> vertical diodes in kilovolt-class applications.