Deva Narayan Pattanayak

n-channel lateral insulated gate transistors: Part I—Steady-state characteristics

The basic physics of the steady-state characteristics of the lateral insulated gate transistor (LIGT) is discussed. Results from a tWo-dimensional computer simulation Of representative LIGT structures are presented. Several Structural and process enhancements to the basic LIGT structure to increase the current handling capability and suppress latchup are pointed out. Experimental results of the steady-state characteristics of a variety of LIGT test structures are presented and analyzed. The static latching aspect of LIGT is discussed insome detail. LIGT devices employing either a buried layer or surface shorts are shown to current limit rather than latching up.

Interaction between monolithic, junction-isolated lateral insulated-gate bipolar transistors

The static and dynamic interaction between monolithically integrated n- and p-channel, high-voltage lateral insulated-gate bipolar transistors (LGBTs) are studied. In the chosen system partition, three common-source, n-channel LIBGTs are monolithically integrated on one chip using junction isolation, while the p-channel counterparts are on a separate chip. Devices on lightly doped substrates, despite their higher forward drop and longer turn-off time than those on heavily doped substrates, exhibited a lesser degree of interaction with adjacent devices, and thus are preferable for power ICs. Even though the steady-state current that flows into the emitters of adjacent devices in the ON-state is small ( >

The effect of substrate doping on the performance of anode-shorted n-channel lateral insulated-gate bipolar transistors

The performance of n-channel lateral-insulated-gate bipolar transistors (n-LIGBTs) with anode shorts on p/sup -/ epi/p/sup +/ substrates is compared to that of anode-shorted n-LIGBTs on p/sup -/ substrates, as well as to that of conventional n-LIGBTs on either substrate. It is shown that both forward-voltage drop and turn-off time are better for anode-shorted devices fabricated on p/sup -/ epi/p/sup +/ substrate than for those on p/sup -/ substrates, due to a larger percentage component of vertical bipolar current and a lower collector resistance. Forward-voltage drops of 3.05 and 3.3 V at 133 A/cm/sup 2/ and turn-off times of 400 and 750 ns have been measured for devices on p/sup -/ epi/p/sup +/ and p/sup -/ substrates respectively. All the LIGBTs showed current limiting at two to four times the ON-state conduction current during dynamic switching.<<ETX>>

Latching in lateral insulated gate bipolar transistors

The maximum gate controllable current of several different lateral insulated gate bipolar transistor (LIGBT) structures have been investigated. It is shown that the turn-on gate resistance affects the latching current of LIGBTs because of the faster turn-on of the lateral current component than the vertical current component. Addition of p+ sinker, n+ buried layer and surface shorts on the cathode side to the basic LIGBT are found to increase the maximum controllable current but addition of surface anode shorts degrades it. The effect of using SIPOS and oxide as surface passivation layer on latching are compared. The maximum controllable current of LIGBTs is shown to decrease with increasing temperature, as expected, but the rate of decrease is slower than the vertical IGBTs. P-channel devices are worse in latching performance than the n-channel counterparts.

Counterdoping of MOS channel (CDC)-a new technique of improving suppression of latching in insulated gate bipolar transistors

A novel technique of improving suppression of latching in insulated-gate bipolar transistors (IGBTs) is proposed and experimentally verified. By counterdoping the channel of the DMOS cell, the doping of the p-base can be increased up to a factor of two. Dynamic latching improvement of 40-80%, corresponding to the p-base doping increase, has been obtained. The degradation in forward blocking voltage was observed when the counterdoping dosage exceeds about 2*10/sup 12/ cm/sup -2/ for 600-V devices.<<ETX>>

Lateral insulated gate transistors with improved latching characteristics

Lateral insulated gate transistors were fabricated to study their applicability for power integrated circuits. Three independent techniques for improving latching current are described in this paper. We obtained devices that latch at 510 A/cm2, significantly greater than previously reported. We have also demonstrated devices that current-limit at 475 A/cm2without latching. Several device configurations are compared in terms of performance and processing trade-offs. In addition, computer simulations suggest a device design improvement that could result in a 30% increase in current density.

Design of Current Sensors in IGBT's

Summary form only given. The operation of current sensors (or pilots) in IGBTs (insulated-gate bipolar transistors) is described experimentally and with two-dimensional simulations. Two different sensor structures are compared. In the most conventional structure, a small IGBT, separated from the main device by metallization only, is used as a current sensor (or pilot) and the emitter of this small IGBT is connected to ground via a resistor. As the voltage at the emitter of the current sensor increases due to increasing current flow, the forward drop across the current sensor decreases and the ratio between the main current and the sensor current decreases. Experimentally, the dependence of the normalized current sensor (or pilot) voltage on the main IGBT current of a 500-V, n-channel, asymmetric IGBT has been shown to be fairly linear, except when a small main current or a large pilot resistor is used. The main-to-pilot current ratio increases with increasing carrier lifetime and increasing distance from the main IGBT. >

Proton implantation in lateral IGBTs

The effect of proton implantation on the performance of n- and p-channel, 500-V lateral insulated gate bipolar transistors (LIGBTs) are studied. It is shown that proton implantation results in a better forward drop vs. turn-off time than conventional electron irradiation. Since proton damage is also more thermally stable than electron damage, proton implantation is a better choice in LIGBT optimization for minimum power loss.<<ETX>>

An adjunct tracking system for low altitude sector aircraft

This paper advances the concept of using slightly modified commercial ground broadcast TV signals to aid in tracking aircraft at low attitude near major airports. The modification of the TV signal is not major and will not affect normal TV operation. The resulting system should be of utility in augmenting air traffic control and could provide an important dual service role for commercial TV ground broadcast. >

Comparison of p-channel lateral insulated-gate bipolar transistors with and without collector shorts

The performances of p-channel lateral insulated-gate bipolar transistors (LIGBTs) with and without collector shorts on n/sup -/ epi/n/sup +/ substrates are compared. The collector-shorted devices have a 4* improvement in turn-off time but about 1-V higher forward drop, due to a substantially reduced vertical current component. The addition of a buried layer on the emitter side increases the forward drop and reduces the turn-off time slightly for both types of LIGBTs. The presence of the collector shorts significantly improves the breakdown voltage but increases the percentage of the lateral current component, leading to a lower maximum gate controllable current.<<ETX>>