Overview of High Voltage SiC Power Semiconductor Devices: Development and Application

Research on high voltage(HV)silicon carbide(SiC)power semiconductor devices has attracted much attention in recent years.This paper overviews the development and status of HV SiC devices.Meanwhile,benefits of HV SiC devices are presented.The technologies and challenges for HV SiC device application in converter design are discussed.The state-of-the-art applications of HV SiC devices are also reviewed.

Recent developments in superjunction power devices

Superjunction(SJ)is one of the most innovative concepts in the field of power semiconductor devices and is often referred to as a"milestone"in power MOS.Its balanced charge field modulation mechanism breaks through the strong dependency between the doping concentration in the drift region and the breakdown voltage V_(B)in conventional devices.This results in a reduction of the trade-off relationship between specific on-resistance R_(on,sp)and V_(B)from the conventional R_(on,sp)∝V_(B)^(2.5)to R_(on,sp)∝W·V_(B)^(1.32),and even to R_(on,sp)∝W·V_(B)^(1.03).As the exponential term coefficient decreases,R_(on,sp)decreases with the cell width W,exhibiting a development pattern reminiscent of"Moore's Law".This paper provides an overview of the latest research developments in SJ power semiconductor devices.Firstly,it introduces the minimum specific on-resistance R_(on,min)theory of SJ devices,along with its combination with special effects like 3-D depletion and tunneling,discussing the development of R_(on,min)theory in the wide bandgap SJ field.Subsequently,it discusses the latest advancements in silicon-based and wide bandgap SJ power devices.Finally,it introduces the homogenization field(HOF)and high-K voltage-sustaining layers derived from the concept of SJ charge balance.SJ has made significant progress in device performance,reliability,and integration,and in the future,it will continue to evolve through deeper integration with different materials,processes,and packaging technologies,enhancing the overall performance of semiconductor power devices.

A review of manufacturing technologies for silicon carbide superjunction devices

Superjunction technology is believed to reach the optimal specific on-resistance and breakdown voltage trade-off.It has become a mainstream technology in silicon high-voltage metal oxide semiconductor field effect transistor devices.Numerous efforts have been conducted to employ the same concept in silicon carbide devices.These works are summarized here.

Analysis and Optimization of the Characteristics of a New IEC-GTO Thyristor

Based on a short anode GTO structure （SA-GTO）,a novel GTO structure called an injection efficiency controlled gate turn off thyristor （IEC-GTO） is proposed,in which the injection efficiency can be controlled via an additional thin oxide layer located in the short anode contact region. The forward blocking, conducting, and switching characteristics are analyzed and compared with an SA-GTO and conventional GTO. The results show that the IEC-GTO can obtain a better trade-off relation between on-state and turn-off characteristics. Additionally,the width of the oxide layer covering the anode region and the doping concentration of the anode region are optimized, the process feasibility is analyzed, and a realization scheme is given. The results show that the introduction of an oxide layer would not increase the complexity of process of the IEC-GTO.

Design Concept for Key Parameters of Reverse Conducting GCT

Presented is design concept for key parameters o f the reverse conducting gate commutated thyristor (RC-GCT),such as the thickness and concentration of n-base region and the transparent anode region,and the wi dth of separation region between asymmetric GCT and PIN diode.A structure model of the RC-GCT is set up based on the design concept and its characteristics are analyzed.The simulation results show the design concept is reasonable.

High current pulse forming network switched by static induction thyristor

A high-current pulse forming network (PFN) has been developed for applications to artificial solar-wind generation. It is switched by staticinduction thyristor (SIThy) and is capable of generating pulsed current of ~9.7 kA for a time duration of ~1 ms. The SIThy switch module ismade that it can be controlled by an optical signal and it can be operated at elevated electrical potential. The experiments reported in this paperused two switch modules connected in series for maximum operating voltage of 3.5 kV. The experimental results have demonstrated a pulsedhigh-current generator switched by semiconductor devices, as well as the control and operation of SIThy for pulsed power application.

Concept and design of super junction devices

The super junction（SJ） has been recognized as the ＂milestone＂ of the power MOSFET, which is the most important innovation concept of the voltage-sustaining layer（VSL）. The basic structure of the SJ is a typical junction-type VSL（J-VSL） with the periodic N and P regions. However, the conventional VSL is a typical resistance-type VSL（R-VSL） with only an N or P region. It is a qualitative change of the VSL from the R-VSL to the JVSL, introducing the bulk depletion to increase the doping concentration and optimize the bulk electric field of the SJ. This paper firstly summarizes the development of the SJ, and then the optimization theory of the SJ is discussed for both the vertical and the lateral devices, including the non-full depletion mode, the minimum specific on-resistance optimization method and the equivalent substrate model. The SJ concept breaks the conventional＂silicon limit＂ relationship of R_（on）∝V_B^（2.5）, showing a quasi-linear relationship of R_（on）∝V_B^（1.03）.

Review of Technologies for High-Voltage Integrated Circuits

High-Voltage power Integrated Circuits(HVICs) are widely used to realize high-efficiency power conversions(e.g., AC/DC conversion), gate drivers for power devices and LED lighting, and so on. The Bipolar-CMOS-DMOS(BCD) process is proposed to fabricate devices with bipolar, CMOS, and DMOS modes, and thereby realize the single-chip integration of HVICs. The basic integrated technologies of HVICs include High-Voltage(HV) integrated device technology, HV interconnection technology, and isolation technology. The HV integrated device is the core of HVICs. The basic requirements of the HV integrated device are high breakdown voltage, low specific on-resistance,and process compatibility with low-voltage circuits. The REduced SURFace field(RESURF) technology and junction termination technology are developed to optimize the surface field of integration power devices and breakdown voltage. Furthermore, the ENhanced DIelectric layer Field(ENDIF) and REduced BULk Field(REBULF) technologies are proposed to optimize bulk fields. The double/triple RESURF technologies are further developed, and the superjunction concept is introduced to integrated power devices and to reduce the specific on-resistance. This work presents a comprehensive review of these technologies, including the innovation technologies of the authors’ group,such as ENDIF and REBULF, substrate termination technology prospective integrated technologies and HVICs in wide band gap semiconductor materials are also discussed.

An analysis of the dynamic avalanche mechanism of an improved FCE diode with a deep p^+ adjusting region

An improved field charge extraction （FCE） diode with a deep p＋ adjusting region at the cathode side is studied. The reverse recovery mechanism and electric field gradient are thoroughly analyzed and validated using ISE simulation results. The results show that, based on the premise of ensuring the static characteristics, the improved FCE diode can clearly improve the softness and effectively suppress the peak electric field of the nnjunction at the cathode side during reverse recovery, and thus has a high dynamic avalanche capability compared with conventional FCE diodes.