High temperature performance of dielectrically isolated LDMOSFETs, LIGBTs and dual channel LESTs with a breakdown voltage of 500 V are compared. The device parameters measured between 25/spl deg/C and 200/spl deg/C include the on-state current, threshold voltage, transconductance and the switching characteristics. The high temperature performance of the LIGBT is found to be superior to the LEST in terms of on-state current at a given forward bias, the parasitic thyristor latching current density, and the turnoff times. The effect of anode shorting and hybrid Schottky anode structures, for both the LIGBT and LEST, on the tradeoff curves are reported for different operating temperatures.< >
Thin film properties of niobium silicide sputtered from a slightly silicon‐rich , cold‐pressed alloy target onto , , and n+ doped poly‐Si have been investigated. The structural and compositional properties were examined with x‐ray diffraction, Rutherford backscattering spectrometry (RBS), and secondary ion mass spectrometry (SIMS). X‐ray diffraction revealed that was the predominant silicide phase present, unlike those films reported previously, which contained significant amounts of an intermediate silicide phase . These films had a Si/Nb ratio of 2.1 as determined from RBS and contained lower levels of common contaminants (such as , , and carbon). Isochronal and isothermal annealing showed that the major decrease in resistivity occurred in the first 5 min, and a resistivity value of ∼70 μΩ‐cm was obtained after annealing at 1000°C. During annealing, phosphorus was found to diffuse through rapidly, similar to other refractory silicides.
The floating base thyristor (FBT) is a new thyristor structure in which its p-base region, containing a p+ region, is not shorted to the n+ emitter. Using the DMOS process, an n-channel and a p-channel MOSFET are integrated with the thyristor structure. The device operates in the thyristor mode with a low ON-state voltage drop at even high current densities when a positive bias is applied to both gates. When a negative bias is applied to the OFF gate, the device operates in the IGBT mode with the saturated current controlled by the positive bias applied to the ON gate.
Abstract : Theoretical and experimental studies were performed to investigate the feasibility for the formation of fusible links by using thin Aluminum films. The results of this research indicate that, by using the Aluminum films of 100 to 200 angstroms in thickness, it is possible to obtain links with fusing currents on the order of 10 milliamperes. These values may be acceptable for the fabrication of large area MOS-gated power devices.
The advent of the SiC Bidirectional FET (BiDFET), a monolithic 1.2 kV bidirectional switch, has rendered the single-stage three-phase AC/DC converter topology a promising approach for implementing AC/DC converters. This topology, which integrates a full-bridge converter with a single-phase to three-phase matrix converter via a high-frequency transformer, is particularly suitable for applications requiring galvanic isolation, buck-boost functionality, and bidirectional power flow. The single-stage design eliminates the need for bulky and unreliable electrolytic capacitors, and utilizes a single magnetic component for power transfer. In the matrix converter, bidirectional switches, which were traditionally implemented using combinations of multiple semiconductor devices such as MOSFETs, IGBTs, and diodes, can now be realized using the single-chip solution, BiDFET. This advancement leads to a lower switch count, compact converter implementation, with lower inductance commutation cells, thereby enhancing the overall efficiency and compactness of the system. The paper presents a unified model of the converter, considering all control parameters, including the duty cycles and phase shift of transformer voltages. Detailed expressions for power transfer, transformer currents, and currents at AC and DC ports are provided. Additionally, the paper outlines the conditions necessary for soft-switching of all switches and the commutation schemes required for the practical implementation of the matrix converter modulation scheme. A hardware prototype of a 10 kW, 480 V RMS, LL / 800 V AC/DC system has been developed, and experimental results are presented to demonstrate its performance.
This paper compares experimentally obtained electrical characteristics of a novel Octagonal (Oct) cell topology for 1.2 kV-rated 4H-SiC JBSFETs with the Linear and Hexagonal (Hex) cell topologies for the first time. The various cell topologies were fabricated using the same process flow at a 6-inch foundry. The third quadrant on-state voltage drop for the JBS diode in the Oct JBSFET was matched with the Linear cell design by using adequate JBS diode area within the cell. Experimental results demonstrate that the Oct JBSFET has 1.7× and 2.2× better HF-FOM [ Ron×Qgd] compared with the Linear and Hex cell JBSFETs, respectively. In addition, the Oct JBSFETs have a much superior [C iss /C rss ] ratio to suppress shoot through currents during high frequency switching.
This paper aims to establish an intuitive model to determine the chip size of 1200V SiC MOSFET for a particular current rating. In order to provide the direction of next generation SiC MOSFETs, the most vital device parameters were investigated, and their quantitative influences are given. Cost analysis, based on the proposed method, shows that it is feasible to achieve the price parity to Silicon IGBTs by concurrent efforts such as improvements on the device innovation, advanced packaging technology, and reduced processing cost by leveraging high volume commercial 150 mm Si Foundries in US.
A new IGT process which implements a self-aligned short is proposed and demonstrated experimentally. The salient feature of the new process is the placement of a poly-Si plug to define the diffusion window of the P+ short. Similar forward conduction characteristics and tradeoffs with turn-off time were obtained for these self-aligned short IGT's when compared to conventional IGT's with nonself-aligned shorts. With a resistive load and no external gate resistor, dynamic latching current was seen to increase with increasing P+ diffusion depth and electron dosage.
In this paper, we report successful fabrication of the first large area, monolithic, 1.2 kV 4H-SiC Bi-Directional FETs (BiDFETs) with integrated JBS diodes in a 6-inch commercial foundry for use in matrix converters. The fabricated BiDFETs support high voltage (>1.2 kV) in the first and third quadrants. They exhibit very low on-resistance of 50 mΩ in the on-state in both quadrants when the 20 V gate bias is applied to both gates, allowing conduction of 20 A with 1 V drop. Fully gate voltage controlled output characteristics are also confirmed in both quadrants.
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