P. Brosselard

Accelerated test for reliability analysis of SiC diodes

The purpose of this work is the analysis of reliable wire bonding schemes for power SiC diodes working at high temperature. The surge current and the power cycling behavior of different wire bonding technologies are analyzed. A dedicated test bench was developed for the surge current and the power cycling reliability tests [1], [2], [3], [4]. It allows an accelerated reliability test, 105 cycles takes just 3 hours. The 10ms half-sinusoidal current pulse test allows observing the effect of the diodes self-heating. The power cycling capability was analyzed using a new concept [1] of observing the evolution of the dissipated energy per pulse, whose increase under constant current test pulse indicates the degradation of the device. These tests were helpful for chosen an enhanced bonding technology able to work at Tjunctio=300°C.)

Novel structures of 3.3kV 4H-SiC BJTs to reduce the Stacking Faults expansion

4H-SiC BJTs have been manufactured on a Norstel epitaxied N⁺/P/N⁻/N⁺ substrate with a combination of mesa and JTE as edge termination. A breakdown voltage of 3.3 kV has been measured at 1µA regardless the active area (0.16 and 1.4 mm²). A current gain of 20 was extracted at 10V-25°C. 70% of the BJTs did not exhibit a current shift, after a 50 hours DC-stress (25°C).

Electrothermal simulations of silicon carbide current limiting devices

SiC is a semiconductor material that could satisfy the requirements of electrical protective devices. This work presents two devices as current limiters for serial protection application. The first device structure is a vertical power MOSFET-like with an existing N channel. The second is a LVJET with buried p-wells and an additional gate electrode. Their electrical performances were simulated with ISE TCAD tools. A study of their electrothermal behavior is presented, demonstrating the SiC superiority over silicon with regards to this field.