• Castelan, Anne
• Rouger, Nicolas, C.
• Couret, Marine
• Letellier, Juliette
• Pernot, Julien
• Driche, Khaled

Abstract

International audience ; In the context of power semiconductor devices, ultra wide bandgap (UWBG) materials offer increased critical electric fields compared to wide-bandgap (WBG) materials [1]. It is the case of monocrystalline diamond which exhibits outstanding physical and thermal properties with, especially, a large critical electric field of 10MV.cm-1 [2] allowing to reach high breakdown voltages. This property combined to the reduced on-state resistance at high junction temperatures (typically 450K) makes diamond power devices a promising challenger to 4H-SiC and GaN based power devices [1]. Recently, a fabricated deep-depletion diamond (D3) MOSFET has reached a critical electric field of 5.4MV.cm-1 [3], far from the estimated 10MV.cm-1. Two-dimensional numerical simulations have pointed out an electric field crowding effect under the gate in both diamond and oxide (Al2O3) layers leading to a premature breakdown of the gate oxide at a drain-source bias of –175V. Consequently, in the view of achieving a 1kV breakdown voltage, specific designs are required to reduce the edge effects. One possible solution to reduce the electric-field crowding effect under the gate is the design of a field-plate, as proposed for Ga2O3 power devices [4]. In this work, a source-field plated diamond MOSFET is designed to match the requirement of 1kV breakdown voltage. The device architecture is based on the lateraldeep-depletion diamond MOSFETs which has been previously introduced [3]. Compared to this design, a passivation layer with Si3N4 is added underneath the field-plate to ensure a proper isolation of the active device. To quantify the capabilities of such design, two-dimensional device simulations are performed using Silvaco ATLAS to determine theoptimal sizing for the field-plate. Thereby, various field-plate extensions at the drain side, LFP, and field-plate heights, hFP, are investigated. Preliminary simulation results show a reduction of the peak electric field under the gate in both diamond and gate oxide layers, ...

Topics

• impedance spectroscopy
• simulation
• semiconductor
• two-dimensional