Marina Antoniou

The Superjunction Insulated Gate Bipolar Transistor Optimization and Modeling

In this paper, we present a detailed analysis and optimization of the superjunction (SJ) insulated gate bipolar transistor (IGBT). The SJ IGBT is a new device that breaks the IGBT limits, i.e., it delivers performance that is dramatically better. More specifically, we demonstrate here that the optimized SJ IGBT can deliver turn-off losses that are at least 50% lower than those of the state-of-art IGBT while maintaining a similarly low on-state performance, both at room temperature and at higher temperatures. The presence of alternating p- and n-pillars in the drift region gives rise to unique characteristics that when optimized can deliver superior performance. This paper also presents a SPICE model of the SJ IGBT under optimized conditions. Its results are in good agreement with the DESSIS simulation results under direct current conditions. This model consists of an intrinsic MOSFET and a parallel combination of wide- and narrow-base p-n-p bipolar junction transistors.

Optimisation of SuperJunction Bipolar Transistor for ultra-fast switching applications

In this work we present a thorough optimisation of the superjunction bipolar transistor based on a new modelling approach. The superjunction bipolar transistor was first proposed in (F. Bauer 2004), but its potential against the most advanced IGBT structures such as field stop (FS), light punch-through or trench IGBTs, has only been briefly discussed. For the first time we report here on the impact of varying the net doping of the n and p drift layer pillars to deliver the best trade-off between the on-state and switching performance. This is carried out both at room temperature and high temperatures. In essence the doping charge in the n & p pillars changes the ratio between bipolar and unipolar conduction in the drift region and therefore alters very significantly the speed and on-state performance of the device. This is a unique effect, un-characteristic to any other power devices known in the field. We demonstrate here through extensive numerical simulations that an optimised superjunction IGBT can lower the turn-off losses by a factor of 2 (or more) when compared to a state-of-the-art field stop (soft punch through) IGBT while maintaining a similarly low on-state voltage drop. We also show here that the SJ concept can deliver significantly improved overall performance when compared to a FS IGBT at lower drift dopings, where the use of charge balance results in lower drift lengths and at high doping levels, where the effect of unipolar conduction at the cathode side of the drift region leads to better on-state/switching trade-off. However there is a middle range of doping levels where the use of the SJ drift region is in fact detrimental to the plasma distribution in the device leading to worse performance than a FS IGBT.

The Soft

The aim of this paper is to demonstrate the application of the superjunction (SJ) design in an insulated gate bipolar transistor (IGBT). Bipolar conduction is present and enhanced at the cathode side of the device, while the p-pillars collect the plasma deep from the anode side, thus significantly enhancing its turn-off speed. The disconnected soft punchthrough + (SPT+) SJ IGBT is similar to the SJ IGBT, which we have previously reported, but the drift region pillars do not extend up to the cathode contact. Instead, the upper part of this device is similar to the SPT+ IGBT, i.e., it features an n+ injector around the p-well and the n-drift region that is lightly doped. The improvement in the overall performance is impressive (25% lower ON-state losses and 30% lower switching losses) and can indeed justify the technology cost associated with the SJ technology. We also demonstrate how this technology can be used to form a snapback-free reverse conducting IGBT.

\hbox{Punchthrough}+

This letter presents a novel lateral superjunction lateral insulated-gate bipolar transistor (LIGBT) in partial silicon-on-insulator (SOI) technology in 0.18-μm partial-SOI (PSOI) high-voltage (HV) process. For an n-type superjunction LIGBT, the p-layer in the superjunction drift region not only helps in achieving uniform electric field distribution but also contributes to the on-state current. The superjunction LIGBT successfully achieves a breakdown voltage (BV) of 210 V with an <i>R</i>_dson of 765 mΩ·mm². It exhibits half the value of specific on-state resistance <i>R</i>_dson and three times higher saturation current (<i>I</i>_dsat) for the same BV, compared to a comparable lateral superjunction laterally diffused metal-oxide-semiconductor fabricated in the same technology. It also performs well in higher temperature dc operation with 38.8% increase in <i>R</i>_dson at 175 ^°C, compared to the room temperature without any degradation in latch-up performance. To realize this device, it only requires one additional mask layer into X-FAB 0.18-μm PSOI HV process.

Superjunction Insulated Gate Bipolar Transistor: A High Speed Structure With Enhanced Electron Injection

In this letter, we report Eoff-versus- Vce tradeoff curves for vertical superjunction insulated-gate bipolar transistors (SJ IGBTs), exhibiting unusual inverse slopes dEoff/dVce >;0 in a transition region between purely unipolar and strongly bipolar device behaviors. This effect is due to the action of p-pillar hole current when depleting the drift layer of SJ IGBTs during turnoff and the impact of current gain on the transconductance. Such SJ IGBTs surpass by a very significant margin their superjunction MOSFET counterparts in terms of power-handling capability and on-state and turnoff losses, all at the same time.

200-V Lateral Superjunction LIGBT on Partial SOI

In this letter, we propose a new device, the Semi-Superjunction (SJ) (Semi-SJ) insulated-gate bipolar transistor (IGBT) (Semi-SJ IGBT). The device offers significant improvement in the on state and switching tradeoff compared with the state-of-the-art FieldStop Trench IGBT (FS IGBT). Furthermore, when compared with a full SJ IGBT, the device has a considerably simpler process of manufacturing as the existing fabrication process for the “CoolMOS” could be used. The Semi-SJ IGBT offers better robustness against cosmic rays compared with an FS IGBT; the failure-in-time per surface area (FIT/A) of the device levels are up to two orders of magnitude lower. Alternatively, by changing the structure parameters, one can improve dramatically the on state versus switching tradeoff while maintaining the same FIT/A levels.

Superjunction IGBT Filling the Gap Between SJ MOSFET and Ultrafast IGBT

This paper focuses on the causes that lead to the final destruction in standard gate-commutated thyristor (GCT) devices. A new 3-D model approach has been used for simulating the GCT which provides a deep insight into the operation of the GCT in extreme conditions. This allows drawing some conclusions on the complex mechanisms that drive these devices to destruction, previously impossible to explain using 2-D models.

The Semi-Superjunction IGBT

The termination design of superjunction (SJ) structures has always been a conceptual and technological challenge. In this letter, we propose new, optimized, elegant, and cost-efficient solutions toward the realization of the first 1.2-kV rated SJ insulated-gate bipolar transistor. The design is based on the utilization of existing layers in the device fabrication line, hence resulting in no extra complexity or cost increase. The proposed design effectiveness is confirmed through extensive numerical simulations.

The Destruction Mechanism in GCTs

This paper evaluates the technique used to improve the latching characteristics of the 200 V n-type superjunction (SJ) lateral insulated-gate bipolar transistor (LIGBT) on a partial silicon-on-insulator. SJ IGBT devices are more prone to latch-up than standard IGBTs due to the presence of a strong pnp transistor with the p layer serving as an effective collector of holes. The initial SJ LIGBT design latches at about 23 V with a gate voltage of 5 V with a forward voltage drop (VON) of 2 V at 300 A/cm2. The latch-up current density is 1100 A/cm2. The latest SJ LIGBT design shows an increase in latch-up voltage close to 100 V without a significant penalty in VON. The latest design shows a latch-up current density of 1195 A/cm2. The enhanced robustness against static latch-up leads to a better forward bias safe operating area.

Towards Achieving the Soft-Punch-Through Superjunction Insulated-Gate Bipolar Transistor Breakdown Capability

In this paper we propose novel designs that enhance the plasma concentration across the Field Stop IGBT. The “p-ring” and the “point-injection” type devices exhibit increased cathode side conductivity modulation which results in impressive IGBT performance improvement. These designs are shown to be extremely effective in lowering the on-state losses without compromising the switching performance or the breakdown rating. For the same switching losses we can achieve more than 20% reduction of the on state energy losses compared to the conventional FS IGBT.