Papers by Author: Marie Laure Locatelli

Abstract: This paper presents OBIC measurements performed at near breakdown voltage on two devices with different JTE doses. Overcurrent has been measured either at the JTE periphery or at the P⁺ border. Such overcurrent is present due to the electric field enhancement near the breakdown voltage. This hypothesis is proved by the electroluminescence. TCAD simulation of two different JTE doses yielded similar results to the OBIC measurements.

Abstract: A polyimide (PI) has been used for the passivation of maximum 7.8 kV 4H-SiC P+N–N+ (PiN) diodes with a 60 µm-thick base epilayer and a junction termination extension (JTE) periphery protection. The dielectric strength of PI films is studied versus area and temperature. The reverse electrical characterization of the PI–passivated PiN diodes is presented for different natures of the environmental atmosphere. The results are compared to those obtained from same devices passivated with a deposited SiO2 thick film. The highest experimental breakdown voltages are obtained for PI–passivated PiN diodes immersed in PFPE oil, with a 5-6 kV typical value, and a 7.3 kV maximum value. Experimental observations are discussed in correlation with the insulating film properties.

Abstract: Characterizations of Al/Polyimide/Al capacitors in a temperature range extended up to 400°C are presented. The aim is to determine the retained BPDA/PPD polyimide (PI) intrinsic dielectric and conduction properties, as a first stage in the evaluation of its ability to be applied as a passivation material for high temperature operating silicon carbide power devices. The dielectric constant, dielectric loss factor, and the static leakage current of the “as-prepared” Al/PI/Al structures are strongly affected above 175°C, reaching critical values at 400°C with regard to the aimed application. However, an evolution of these characteristics after the sample exposure at high temperature is observed, resulting in a very good and stabilized electrical behavior even at 400°C.

Abstract: Silicon carbide (SiC) is a wide bandgap semiconductor suitable for high-voltage, highpower and high-temperature applications [1]. However, and among other issues, the production of advanced SiC power devices still remains limited due to some shortcomings of the dielectric properties of the passivation layer [2]. Due to their supposed high operating temperature and dielectric strength [3], spin coated polyimide materials appear as a possible candidates for SiC device passivation and insulation purposes. As a matter of fact, they are already used in current commercial SiC devices allowing a maximum junction temperature of 175 °C. The aim of this paper is to study the ability of polyimide (PI) coatings to be used for a Tjmax up to 300 °C. Therefore, the main electrical properties (dielectric permittivity, leakage current and breakdown field) at different temperatures of a high temperature commercially available polyimide material (from HD Microsystems) in both Metal-Insulator-Semiconductor (MIS) and Metal-Insulator-Metal (MIM) structures are presented and discussed.