This paper gives an overview about different failure mechanisms which limit the safe operating area of power devices. It is demonstrated how the device internal processes can be investigated by means ...of device simulation. For instance, the electrothermal simulation of high-voltage diode turn-off reveals how a backside filament transforms into a continuous filament connecting the anode and cathode and how this can be accompanied with a transition from avalanche-induced into thermally driven carrier generation. A similar current destabilization may occur during insulated-gate bipolar transistor turn-off with a high turn-off rate, when the channel is closed quickly leading to strong dynamic avalanche. It is explained how the current filamentation depends on substrate resistivity, device thickness, channel width, and switching conditions (gate resistor and overcurrent). Filamentation processes during short-circuit events are discussed, and possible countermeasures are suggested. A mechanism of a periodically emerging and vanishing filament near the edge of the chip is presented. Examples on current destabilizing effects in gate turn-off thyristors, integrated gate-commutated thyristors, and metal-oxide-semiconductor field-effect transistors are given, and limitations of current device simulation are discussed.
Evolution of thyristor technology and the design concepts, which brought and maintain the phase control thyristor (PCT) at the top of a power pyramid, are discussed. The state-of-the-art device ...concepts like electrically triggered thyristor and light triggered thyristor are described for voltage classes up to 8.5 kV and maximal on-state rated current of 6 kA. Main focus is laid on the PCTs for high-voltage direct current transmission, the enabler of power transmission beyond the 10-GW level.
Progress in IGBT development Niedernostheide, Franz-Josef; Schulze, Hans-Joachim; Laska, Thomas ...
IET power electronics,
04/2018, Letnik:
11, Številka:
4
Journal Article
Recenzirano
Recent progress in insulated gate bipolar transistor (IGBT) development is reviewed. Highlighted issues range from technological aspects such as special processes suitable for thin-wafer-processing, ...through the advanced cell and vertical concepts to approaches for improved IGBT ruggedness. Latest advancements regarding thermal management in both modules and discrete chips are also addressed.
Up to now the vast majority of insulated gate bipolar transistors (IGBTs) has been produced on silicon (Si) wafers out of the float-zone (FZ) process. FZ crystals can easily be used for this ...application, but are only available with a diameter of up to 200 mm. However, the use of wafer substrates with a diameter of 300 mm offers a significant increase in productivity and is therefore the diameter of choice for the high-volume production of CMOS devices. In order to benefit from this advantage also for the manufacturing of IGBTs, material out of the magnetic Czochralski process, which is available in 300 mm, had to be adapted. Key issues include crystal originated particles, dopant segregation along the crystal axis, and the higher concentration of oxygen. In particular, the implementation of the field-stop zone by the implantation of protons will lead to the additional formation of hydrogen-decorated CIOI complexes which can act electrically as donors. However, by an appropriate adjustment of the processing parameters the electrical characteristics of IGBTs on FZ substrates can be well reproduced.
This work investigates modification on the top-side aluminium (Al) metallisation of 1.2 kV insulated-gate bipolar transistors (IGBTs) under repetitive short-circuit (SC) type-I measurements for two ...different parasitic inductances of 45 and 380 nH. The presence of current–density filaments starting at the collector side during SC leads to local temperature increase of the emitter metallisation and thus to modification of the top Al surface in the pattern of the current filaments. Here, two techniques thermo-reflectance microscopy, which can detect the surface temperature during repetitive short circuits directly and Al modifications after repetitive SC with analysis under optical microscope after the test have been considered. At 45 nH, with different DC-link voltages from 300 to 600 V, the Al modification pattern is non-uniform and it becomes uniform for VDC>600 V. However, for 380 nH parasitic inductance and for DC-link voltages 300 and 400 V, the Al reconstruction shows a non-uniform pattern and becomes uniform for VDC≥500 V. The SC simulations were performed by using a simplified front-side IGBT structure using variable DC-link voltages and inductances to reproduce the filament behaviour.
An analysis of the plasma front velocities during turnoff of a power diode is used to explain the differences between the formation and the behavior of cathode-side and anode-side filaments. Device ...simulations show, how cathode-side filaments may trigger a thermal runaway at the end of a reverse-recovery period of diodes turned off with extremely high current rates operating the diode in a regime far away from the safe operating area. From the transient voltage curve, the analysis of the reverse-recovery charge as a function of the dc-link voltage and an analysis of the turnoff transients in the current-voltage phase space, it is, however, deduced that the appearance of a cathode-side filament by itself does not necessarily lead to diode destruction. The transformation of the initially avalanche-generated filaments into filaments that are essentially driven by thermal mechanism seems to be a further important condition for device destruction.
The use of silicon wafer substrates with a diameter of 300 mm for the manufacturing of electronic devices strongly increases the overall productivity of a device manufacturing line. However, ...float‐zone (FZ) silicon, which is traditionally used for insulated gate bipolar transistors (IGBTs), is not available for wafer diameters exceeding 200 mm. Therefore, a silicon material fabricated by the magnetic Czochralski (m:Cz) method has to be used for IGBT production on 300 mm wafers. Critical issues of this material are the so‐called crystal originated particles (COPs) and the strong axial variation of the doping level along the crystal. Furthermore, the m:Cz material contains a relatively high concentration of oxygen so that the influence of carbon/oxygen complexes has to be considered. CIOI complexes can be decorated with hydrogen atoms, resulting in donor‐like complexes. In particular, the application of proton irradiation for the doping of the field‐stop zone results in a relatively high concentration of interstitial carbon, which is continuatively associated with the generation of undesired donors. It is shown that the electrical behavior of IGBTs fabricated on FZ substrates can be well reproduced using the m:Cz material if the parameters of the hydrogen implantation are adjusted appropriately.
The use of 300 mm silicon wafers strongly increases the productivity of a manufacturing line for insulated gate bipolar transistors. However, 300 mm float‐zone silicon is not available, so that the Czochralski material is required. For this, several critical issues have to be solved: crystal originated particles, the axial‐doping variation along the crystal, and the minimization of the concentration of CIOIH complexes.
Defect engineering for modern power devices Job, Reinhart; Laven, Johannes G.; Niedernostheide, Franz-Josef ...
Physica status solidi. A, Applications and materials science,
10/2012, Letnik:
209, Številka:
10
Journal Article
Recenzirano
Radiation‐induced defects are a common tool in the manufacturing of modern power semiconductor devices. Hydrogen‐related doping is a feasible method to introduce deep doping profiles with a low ...thermal budget. The hydrogen‐related donors (HDs) require radiation damage and hydrogen, which can be induced by different methods, e.g., proton implantation, helium and proton co‐implantation, or an implantation followed by a hydrogen‐plasma step. The choice of these methods significantly affects the introduction efficiency of the donors and the necessary post‐implantation thermal budget. By controlling the hydrogen‐to‐damage ratio, the manufacturing process of the HD profiles may be moved on a trade‐off between the activation efficiency and the necessary thermal budget. A low hydrogen‐to‐damage ratio leads to an increased activation of the HDs, whereas a high hydrogen‐to‐damage ratio reduces the necessary diffusion time of the hydrogen during the post‐implantation anneal. For the technical usage of hydrogen‐related doping, knowledge of an efficient process window is desirable. In this paper, we consider proton implantation, helium and proton co‐implantation, and a proton implantation followed by a hydrogen‐plasma step as different introduction methods of HD profiles with regard to the activation efficiency of the HDs and the necessary thermal budget.
The surge-current ruggedness of free-wheeling diodes can be improved by implementing the self-adjusting p emitter efficiency diode concept (SPEED). Simulations indicate that the switching ruggedness ...is reduced because of the occurrence of cathode-side filaments during reverse-recovery. Experiments confirm the weak switching performance of such a diode in comparison to a conventional diode. By implementing the controlled injection of backside holes concept cathode-side filaments can be suppressed. However, this measure is not sufficient to regain the switching ruggedness of a conventional diode. It is also necessary to fully embed the p+-areas of the SPEED anode in the low-doped p-type area to avoid high electrical field strengths at the p+p-junction and pinning of anode-side filaments. However, anode-side adjustments for improving the switching ruggedness can reduce the benefit of the SPEED concept regarding the surge-current capability.
