Investigations on mesa width design for 4H–SiC trench super junction Schottky diodes

Abstract

Mesa width (W M ) is a key design parameter for SiC super junction (SJ) Schottky diodes (SBD) fabricated by the trench-etching-and-sidewall-implant method. This paper carries out a comprehensive investigation on how the mesa width design determines the device electrical performances and how it affects the degree of performance degradation induced by process variations. It is found that structures designed with narrower mesa widths can tolerant substantially larger charge imbalance for a given BV target, but have poor specific on-resistances. On the contrary, structures with wider mesa widths have superior on-state performances but their breakdown voltages are more sensitive to p-type doping variation. Medium W M structures (∼ 2 µm) exhibit stronger robustness against the process variation resulting from SiC deep trench etching. Devices with 2-µm mesa width were fabricated and electrically characterized. The fabricated SiC SJ SBDs have achieved a breakdown voltage of 1350 V with a specific on-resistance as low as 0.98 mΩ•cm 2 . The estimated specific drift onresistance by subtracting substrate resistance is well below the theoretical one-dimensional unipolar limit of SiC material. The robustness of the voltage blocking capability against trench dimension variations has also been experimentally verified for the proposed SiC SJ SBD devices.

A Review: Inductively Coupled Plasma Reactive Ion Etching of Silicon Carbide

“…The ICP-RIE etching technology of structures entails the need to produce patterns in the form of vertical, smooth walls forming: holes, deep and narrow trenches or islands [ 23 , 24 ]—the so-called MESA structures (exemplary various etched patterns are shown in Figure 1 ). Etched parts are used, among others, for interconnections and insulation in integrated circuits, diffractive structures in optoelectronic systems, or for creation of complex MEMS.…”

Performance analysis of 4H-SiC super-junction devices: impact of trench angle and improvement with multi-epi structure

“…Such result is mainly due to the high electric field generated by the lateral depletion of the super-junction structure. The detailed discussion on the lateral depletion can be found in our previous work [26].…”