D.W. Green

Realizing high-voltage junction isolated LDMOS transistors with variation in lateral doping

High-voltage lateral diffused metal-oxide semiconductor (LDMOS) transistors with a variation in the lateral doping (VLD) of drift regions are demonstrated in junction isolation technology using a fully implanted CDMOS process. The VLD profile is realized by using an analytical approach reported previously. The analytical model is verified through simulations and experiment. Results indicate that higher breakdown voltages can be achieved for a given drift length using a VLD profile in comparison to uniform doping while offering a good tradeoff between breakdown voltage and specific on-resistance.

Anode Engineering for the Insulated Gate Bipolar Transistor—A Comparative Review

Significant effort has been placed in anode engineering for the insulated gate bipolar transistor (IGBT) as a method to enhance the on-state/switching loss tradeoff. For the first time, we have taken a comprehensive selection of these designs and individually implemented them all into a 1200 V vertical structure. It is shown that all passive anode engineering structures lie on or above a forward voltage drop/inductive turn-off loss tradeoff curve which can also be generated through changing the emitter (anode) Gummel number of a conventional IGBT. Tradeoff enhancement can be achieved through the use of active anode structures. Such structures incorporate an additional gate at the anode and are considered in the study. The influence of lifetime on the tradeoff is considered and it is shown that optimum device performance can be achieved through both control of the lifetime and the emitter Gummel number/anode engineering. The relative shift in the tradeoff curve is also considered for optimum device design. Furthermore, the effect of the tradeoff curve on the total power loss with varying switching frequency and duty cycle is also discussed. high temperature operation, it is shown that the shift must be carefully considered for optimum device design. Furthermore, the effect of the tradeoff curve on the total power loss with varying switching frequency and duty cycle is also discussed.

Performance analysis of the segment npn anode LIGBT

The performance of a high-voltage lateral insulated gate bipolar transistor (LIGBTs) with segmented n+p/n anode fabricated in junction isolation technology is experimentally investigated at both room and elevated temperatures. Detailed two dimensional numerical modeling of a vertical representation of the structure shows that significant electron current passes through the n/sup +/p/n segment of the anode region during the on-state and when devices are subjected to clamped inductive switching. It is shown that the magnitude of electron current can be controlled by modifying the p-base charge which enables enhancement of the turn-off loss/forward voltage drop tradeoff in comparison to conventional LIGBTs.

Design and analysis of multichannel LIGBTs in junction isolation technology

Performance of multichannel lateral insulated gate bipolar transistors (MC-LIGBTs) fabricated in a cost-effective, fully implanted, CDMOS-compatible process in junction isolation technology is reported. Due to the presence of additional MOS cathode cells, the MC concept enables a reduction in the forward voltage drop. Furthermore, the MC concept is combined with the segmented N/sup +/P/P/sup +/ anode (SA-NPN) concept in an LIGBT structure. The SA-NPN anode concept reduces turnoff losses due to a reduction in injection of holes and from the collection of electrons by the narrow base-collector shorted NPN bipolar transistor formed at the anode. It is shown that combining the MC and the SA-NPN Anode concepts creates a device that exhibits both low on-state and turnoff losses and thus best placed for use in power IC applications.

Fully Isolated High Side and Low Side LIGBTs in Junction Isolation Technology

It is well known that the operating conditions of adjacent LIGBTs is greatly restricted in JI technology due to severe cross-talk limitations. Extensive investigations reveal that grounded guard rings are ineffective to prevent such cross-talk. To overcome this problem, a new isolation technique is proposed herein. It is shown that cross-talk suppression can be achieved through using a combination of deep oxide filled trenches made through the back of the wafer and a single grounded guard ring. It is shown that the width and depth of the oxide trenches are quite tolerant to dimensional fluctuations. Furthermore, the solution is shown to be easily extendable to realise compact, monolithic integration of both low-side and high-side LIGBTs in junction isolation technology

Analysis of lateral IGBT with a variation in lateral doping drift region in junction isolation technology

This brief demonstrates the measured and simulated performance of a high-voltage junction-isolated lateral insulated-gate bipolar transistor (LIGBT) with a variation in lateral doping (VLD) drift region. Both experimental and simulation results show that significant advancements in breakdown voltages (BVs) and latch-up current densities can be obtained using this technology without compromising the forward voltage drop. The results validate that a VLD drift region can achieve the required BV with smaller drift region lengths, in comparison to conventional LIGBTs using uniform drift region technology, and that the VLD drift region technology enhances the safe operating area

Transient substrate currents in junction-isolated lateral IGBT

In this brief, experimental results of transient substrate currents that occur during clamped inductive switching of a junction-isolated lateral insulated gate bipolar transistor are analyzed. The transient substrate current peak at turn off is broader and higher than the value at turn on. The peak substrate current increases with increasing anode voltage, and anode injection efficiency significantly influences the characteristics of the transient currents. Two-dimensional numerical simulations are used to evaluate the internal dynamics of the device. It is shown that the Kirk effect is responsible for the transient currents during the switching of a lateral insulated gate bipolar transistor.

Interaction between monolithically integrated JI-LIGBTs under clamped inductive switching

Due to the increasing demand for multi-functionality in power integrated circuits, consideration must be given as to how multiple, adjacent, monolithically integrated, high voltage lateral power devices interact with each other when operated independently of one another. For the first time, we demonstrate through extensive experiments and simulations that the breakdown, on-state, switching and safe operating area performance of LIGBT are all significantly affected by the operating conditions of an adjacent LIGBT in junction isolation technology.

RESURFed Quasi Lateral IGBT Structure for High Current PICs

In this paper a new power device architecture is proposed. The concept is shown to significantly enhance the current carrying capability of devices suitable for integration in power integrated circuits (PICs). The concept combines the advantages of the RESURF principle under blocking conditions to yield a compact device and uses multiple MOSFET cathode cells, formed on the backside of the wafer to yield a high level of vertical current modulation in the on-state. The new architecture is shown to significantly enhance the forward bias safe operating area and also the forward voltage drop by more than 50%. Critically, it is also shown that the additional backside cathode cells have a minimal effect on the turn-off losses in comparison to a conventional lateral IGBT.