Novel Cathode Design to Improve the ESD Capability of 600 V Fast Recovery Epitaxial Diodes

Abstract

Abstract:Silicon power diodes are used to design different types of electrical energy systems. Their performance has been improved substantially, as a result of a concentrated research efforts that have taken place in the last two decades. They are considered immune to electrostatic discharge (ESD) failures, since usually they withstand an avalanche energy one order of magnitude higher than that of the ESD. Consequently, few works consider this aspect. However, it was observed that during the mounting of power diodes in automotive systems (e.g., with operators touching and handling the devices), ESD events occur and devices fail. In this paper the ESD capability of 600 V fast recovery epitaxial diode (FRED) is analyzed by means of Technology Computer-Aided Design (TCAD) simulations, theoretical analyses and experimental characterization. Two doping profiles are investigated in order to improve the ESD robustness of a standard device and an optimized doping profile is proposed. The proposed design exhibits a higher ESD robustness and this is due to its superior capability in keeping the current distribution uniform in the structure in a critical condition such as the impact ionization avalanche effect. Both experimental and numerical results validate the proposed design.

Development of an HBM-ESD tester for power semiconductor devices

“…Therefore, the setup board design was carried out with very low parasitic capacitance and inductance. However, the DUT itself may be the origin of the oscillations and their evolution may give information about the current distribution into DUT, as reported in [2]. In Fig.…”

“…Numerical results in highlight as the higher di/dt occurring during the HBM-ESD test leads to the occurrence of failures different from that of UIS. As reported in [2], unexpected effects as current filamentation may occur during the ESD test, leading to premature failure. Typically, the current filamentation leads to a strong variation of the Cathode voltage.…”

“…1a). However, the last requirements in the field of automotive concern about the reliability in terms of HBM-ESD [2] (A sketch of the UIS test schematic is reported in Fig. 1b).…”

“…Typically, the HBMESD event is not considered detrimental for power diodes. However, recent studies highlight as power diodes may fail under electrostatic discharge [2], unexpectedly. The HBM-ESD capability concerns the reliability in handling procedures for mounting discrete power diodes is automotive applications, such as DC-DC converters or inverters.…”

“…The main disadvantage of the commercial ESD tester is the impossibility to measure the current and voltage waveforms occurring at the terminals of the DUT during the test. Results in [2] show as the cathode voltage waveform during the HB-ESD test gives important information about the current distribution over the time. In this work we present an HBM-ESD tester capable to measure the electrical waveforms, with a consequent gain in the comprehension of the failure events.…”