Silicon nitride, a high potential dielectric for 600 V integrated RC-snubber applications

Abstract

Monolithically integrated RC-snubbers were realized by metal-insulator-semiconductor capacitors on a silicon substrate also serving as a series resistor. These devices provide a promising alternative to passive surface-mounted device components that are commonly used for snubber applications in power electronic circuits. The surface area of the substrate was enlarged with circular trench structures to increase the integration level of the capacitor, and a silicon nitride layer with a thickness of 1.05 μm was deposited on top of a 20 nm-thin silicon oxide layer as a potential dielectric for applications up to 600 V. With the trench geometry, a capacitance per surface area of 0.6 nF/mm2 was achieved, which is more than ten times the capacitance of a planar device using the same dielectric layers. However, combining the thick silicon nitride layer with the trench geometry caused an excessive wafer bow of nearly 800 μm, so deposition and structuring of a surface passivation layer, such as polyimide, was not feasible. Therefore, inert oil had to be used as a surface passivation for high voltage measurements. The silicon nitride dielectric exhibits a leakage current density lower than 0.3 nA/mm2 at the requested 600 V operating voltage, while dielectric breakdown of the devices is observed at 1050 V. A low deviation in capacitance and series resistance across the wafer and a high yield regarding the high voltage stability is achieved because of the good quality and homogeneity of the silicon nitride dielectric layer.

Effect of microstructures on dielectric breakdown strength of sintered reaction‐bonded silicon nitride ceramics

“…calculated the theoretical DBS of Si 3 N 4 as 1020 kV/mm from the physical parameters. In addition, the DBS of Si 3 N 4 thin film (<1 μm), which is Si 3 N 4 containing no grain boundary phase, was higher than 100 kV/mm 29–33 . Therefore, it is considered that Si 3 N 4 grains having a sufficiently high DBS were not the defects for the dielectric breakdown.…”

“…In addition, the DBS of Si 3 N 4 thin film (<1 μm), which is Si 3 N 4 containing no grain boundary phase, was higher than 100 kV/mm. [29][30][31][32][33] Therefore, it is considered that Si 3 N 4 grains having a sufficiently high DBS were not the defects for the dielectric breakdown. With respect to grain boundary phase, the grain boundary had the amorphous structure like a glass.…”

Switching SiC Devices Faster and More Efficient Using a DBC Mounted Terminal Decoupling Si-RC Element

“…The Si-RC Element Technology. The Si-RC network that was integrated in the power module is based on a 600 V chip design, which was demonstrated at [7], as the 1200 V version is still under development. The composition of the device is in Figure 7, which shows a cross-section image of the capacitor structure recorded with a scanning electron microscope.…”