Dethard Peters

Charge Pumping Measurements on Differently Passivated Lateral 4H-SiC MOSFETs

This paper shows a successful transfer of the charge pumping (CP) method, which is extensively applied on silicon (Si) transistors, to Si carbide (SiC) lateral MOSFETs to characterize the quality of the SiC/SiO2 interface near the conduction and valence band edges. In particular, the constant base technique provides more accuracy and flexibility with respect to the most commonly used constant amplitude technique. Anomalous phenomena previously reported in literature, such as the so-called geometric component, are absent if the measurements are performed on transistors with optimized geometry and if the parameters of the applied CP gate pulses are carefully chosen. Furthermore, interface properties of gate oxides subjected to different postoxidation treatments are compared using this technique and the influence of the measurement parameters and temperature on the resulting CP signal is discussed.

Interface defects in SiC power MOSFETs - An electrically detected magnetic resonance study based on spin dependent recombination

This study presents electrically detected magnetic resonance (EDMR) measurements on a silicon carbide (SiC) MOSFET having the structure of a double-diffused silicon MOSFET (DMOS). The resonance pattern of a SiC DMOS was measured by monitoring the change of the recombination current between the source/body and the drain. The amplitude of the response has a maximum when the device is biased in depletion due to the equal concentrations of electrons and holes at the interface resulting in the most efficient recombination. The measured anisotropic g-tensor has axial symmetry with g∥ = 2.0051(4) (B ‖ c-axis), and g⊥ = 2.0029(4) (B⊥ c-axis) and the pattern shows several hyperfine (HF) peaks. We tentatively identify the observed defect as a silicon vacancy located directly at the interface.

Electrically detected magnetic resonance of carbon dangling bonds at the Si-face 4H-SiC/SiO2 interface

SiC based metal-oxide-semiconductor field-effect transistors (MOSFETs) have gained a significant importance in power electronics applications. However, electrically active defects at the SiC/SiO2 interface degrade the ideal behavior of the devices. The relevant microscopic defects can be identified by electron paramagnetic resonance (EPR) or electrically detected magnetic resonance (EDMR). This helps to decide which changes to the fabrication process will likely lead to further increases of device performance and reliability. EDMR measurements have shown very similar dominant hyperfine (HF) spectra in differently processed MOSFETs although some discrepancies were observed in the measured g-factors. Here, the HF spectra measured of different SiC MOSFETs are compared, and it is argued that the same dominant defect is present in all devices. A comparison of the data with simulated spectra of the C dangling bond (PbC) center and the silicon vacancy (VSi) demonstrates that the PbC center is a more suitable can...

Performance and ruggedness of 1200V SiC — Trench — MOSFET

This paper describes a novel SiC trench MOSFET concept. The device is designed to balance low conduction losses with Si-IGBT like reliability. Basic features of the static and dynamic performance as well as short circuit capability of the 45mΩ/1200 V CoolSiC™ MOSFET are presented. The favorable temperature behavior of the on-state resistance combined with a low sensitivity of the switching energies to temperature simplify the design-in. Long-term gate oxide tests reveal a very low extrinsic failure rate well matching the requirements of industrial applications.

Influence of Oxide Processing on the Defects at the SiC-SiO2 Interface Measured by Electrically Detected Magnetic Resonance

Anneals in nitrogen (N) containing atmosphere have been proven as efficient means of improving the channel mobility of SiC MOSFETs. It has been demonstrated that simultaneously the density of interface traps is reduced. However, this process is not yet fully understood. In this study we show a comparison of MOSFETs annealed in different atmospheres and compare their electrically detected magnetic resonance (EDMR) spectra with electrical parameters. We find hints for the N incorporation not only passivating but also creating or transforming defects.

1200V SiC Trench-MOSFET optimized for high reliability and high performance

A detailed analysis of the typical static and dynamic performance of the new developed Infineon 1200V CoolSiCTM MOSFET is shown which is designed for an on-resistance of 45 mΩ. In order to be compatible to various standard gate drivers the gate voltage range is designed for-5 V in off-state and +15 V in on-state. Long term gate oxide life time tests reveal that the extrinsic failure evolution follows the linear E-model which allows a confident prediction of the failure rate within the life time of the device of 0.2 ppm in 20 years under specified use condition.

MOS Interface Characteristics of In Situ Ge-Doped 4H-SiC Homoepitaxial Layers

We report on the electrical characterization of the Metal-Oxide-Semiconductor (MOS) interfacerealized on in-situ Ge-doped n-type 4H-SiC epilayers grown by Chemical Vapour Deposition(CVD). In order to study the relevance of this novel material for MOSFET technology, and in particularwhether the Ge presence deteriorates the SiC/SiO2 interface, we investigated the electrical propertiesof MOS capacitors realized on this novel substrate. Capacitance-Voltage measurements, performedto determine the quality of the SiC/SiO2 interface, show that the interface traps concentration is notincreased by the Ge content. The current through the oxide layer, monitored to study the bulk oxidequality and the tunneling mechanisms, indicates that Fowler-Nordheim conduction occurs and that thesubstrate-to-oxide barrier for electrons is comparable to the reported values for the SiC/SiO2 system.