The reliability of a power converter depends mainly on the endurance of its main component, the power semiconductor. Therefore, particular attention is paid in this chapter to understand the models that allow the identification of features and early indicators of problems that establish the groundwork for early fault diagnosis in inverters. The two major switch technologies that control the market are field-effect transistors (FETs) and insulated gate bipolar transistors (IGBTs), which are bipolar devices integrating concepts from bipolar junction transistors (BJTs; IGBTs) which are bipolar devices integrating concepts from BJTs and FETs. From the beginning of power electronics, silicon-based semiconductors have been the undisputed king, but modern silicon-based power semiconductors are being challenged by silicon carbide (SiC) and more recently by gallium nitride (GaN). Regardless of the semiconductor material, early diagnostics in semiconductors are based not only on the understanding of the failure mechanisms but also on the “parasitic structures” that are intrinsically associated with the fabrication of the device. The identification and characterization of these “parasitic or associated structures” allow for the development of unified models with general characteristics across different materials and structures of power semiconductors. The aging effects are, in general, reflected in the parasitic structures early in the process of degradation, creating an ideal approach for understanding failure propagation. Fortunately, semiconductor devices share a similar structure, and a standard model across all power semiconductors is used in this chapter to understand aging and to enable early diagnostics.

Chapter Contents:

• 2.1 Introduction
• 2.1.1 Power device stress factors
• 2.1.2 Silicon power MOSFET structure and parasitics
• 2.1.3 SiC power MOSFET structure and parasitics
• 2.1.4 GaNs structure and parasitics
• 2.1.5 IGBT structure and latch-up
• 2.2 Switching process in semiconductors
• 2.2.1 Field distortion acceleration model
• 2.3 Relevant indicators in power semiconductors
• 2.3.1 Voltage Vth and capacitance shift
• 2.3.1.1 Fundamental equations and modeling of Vth displacement and capacitance change by aging
• 2.3.2 Ringing characterization and turn-on delay
• 2.3.3 Detachment and wire bond fatigue
• 2.3.3.1 Detachment in GANs
• 2.3.3.2 Wire bond and solder bond fatigue
• 2.3.3.3 Present and future in life estimation models
• 2.3.4 Junction temperature of power semiconductor
• 2.3.4.1 Observer based for junction temperature estimation
• 2.3.4.2 Device selection observer
• References

Inspec keywords: semiconductor device reliability; failure analysis; power bipolar transistors; gallium compounds; semiconductor device models; power MOSFET; ageing; III-V semiconductors; wide band gap semiconductors; silicon compounds; power semiconductor devices; insulated gate bipolar transistors; invertors; fault diagnosis; power convertors

Other keywords: insulated gate bipolar transistors; power electronics; FET; aging effects; silicon-based power semiconductors; bipolar devices; MOSFET; IGBT; GaN; failure propagation; BJT; SiC; inverters; power converter reliability; fault diagnosis; power semiconductors diagnosis; failure mechanisms; gallium nitride; silicon carbide; bipolar junction transistors; field-effect transistors; power semiconductors model; parasitic structures; degradation process

Subjects: Power semiconductor devices; Reliability; Bipolar transistors; DC-AC power convertors (invertors); Semiconductor device modelling, equivalent circuits, design and testing; Insulated gate field effect transistors; Power electronics, supply and supervisory circuits