An object is to provide a semiconductor device of which a manufacturing process is not complicated and by which cost can be suppressed, by forming a thin film transistor using an oxide semiconductor film typified by zinc oxide, and a manufacturing method thereof. For the semiconductor device, a gate electrode is formed over a substrate; a gate insulating film is formed covering the gate electrode; an oxide semiconductor film is formed over the gate insulating film; and a first conductive film and a second conductive film are formed over the oxide semiconductor film. The oxide semiconductor film has at least a crystallized region in a channel region.

Semiconductor device, and manufacturing method thereof

http://hotstreamer.deanostoybox.com/temp/Ciappa_paper.pdf

Selected failure mechanisms of modern power modules

A power semiconductor device includes trenches disposed in a first base layer of a first conductivity type at intervals to partition main and dummy cells, at a position remote from a collector layer of a second conductivity type. In the main cell, a second base layer of the second conductivity type, and an emitter layer of the first conductivity type are disposed. In the dummy cell, a buffer layer of the second conductivity type is disposed. A gate electrode is disposed, through a gate insulating film, in a trench adjacent to the main cell. A buffer resistor having an infinitely large resistance value is inserted between the buffer layer and emitter electrode. The dummy cell is provided with an inhibiting structure to reduce carriers of the second conductivity type to flow to and accumulate in the buffer layer from the collector layer.

Power semiconductor device

This paper reviews recent trends in power semiconductor device technology that are leading to improvements in power losses for power electronic systems. In the case of low voltage ( 100 V) power rectifiers, the silicon P-i-N rectifier continues to dominate but significant improvements are expected by the introduction of the silicon MPS rectifier followed by the GaAs and SiC based Schottky rectifiers. Equally important developments are occurring in power switch technology. The silicon bipolar power transistor has been displaced by silicon power MOSFETs in low voltage ( 100 V) systems. The process technology for these MOS-gated devices has shifted from V-MOS in the early 1970s to DMOS in the 1980s, with more recent introduction of the UMOS technology in the 1990s. For the very high power systems, the thyristor and GTO continue to dominate, but significant effort is underway to develop MOS-gated thyristors (MCTs, ESTs, DG-BRTs) to replace them before the turn of the century. Beyond that time frame, it is projected that silicon carbide based switches will begin to displace these silicon devices.

Trends in power semiconductor devices

A review of the basic mechanisms affecting the stability of the threshold voltage in response to a bias-temperature stress is presented in terms of the charging and activation of near-interfacial oxide traps. An activation energy of approximately 1.1 eV was calculated based on new experimental results. Implications of these factors, including the recovery of some bias-temperature stress-activated defects, for improved device reliability testing are discussed.

Basic Mechanisms of Threshold-Voltage Instability and Implications for Reliability Testing of SiC MOSFETs

An overview on the history of the development of insulated gate bipolar transistors (IGBTs) as one key component in today’s power electronic systems is given; the state-of-the-art device concepts are explained as well as an detailed outlook about ongoing and foreseeable development steps is shown. All these measures will result on the one hand in ongoing power density and efficiency increase as important contributors for worldwide energy saving and environmental protection efforts. On the other hand, the exciting competition of more maturing Si IGBT technology with the wide bandgap successors of GaN and SiC switches will go on.

IGBT History, State-of-the-Art, and Future Prospects

An insulated gate thyristor includes a first-conductivity-type base layer having a high resistivity, first and second second-conductivity-type base regions formed in a surface layer of the first-conductivity-type base layer, a first-conductivity-type source region formed in a surface layer of the first second-conductivity-type base region, and a first-conductivity-type emitter region formed in a surface layer of the second second-conductivity-type base region. The thyristor further includes a gate electrode formed through an insulating film on the first second-conductivity-type base region, an exposed portion of the first-conductivity-type base layer and the second second-conductivity-type base region, a first main electrode that contacts both the first second-conductivity-type base layer and first-conductivity-type source region, a second-conductivity-type emitter layer formed on the first-conductivity-type base layer, a second main electrode that contacts the second-conductivity-type emitter layer, and an insulating film covering entire areas of surfaces of the second second-conductivity-type base region and first-conductivity-type emitter region. The second second-conductivity-type base region has a diffusion depth that is greater than a larger one of diffusion depths of the first second-conductivity-type base region and a second-conductivity-type well region included in the first second-conductivity-type base region.

Insulated gate thyristor

The mechanisms of destructive failure of an insulated gate bipolar transistor (IGBT) at short-circuit state are discussed. Results from two-dimensional numerical simulation of p-channel and n-channel IGBTs are presented. It is found that there are two types of destructive failure mechanisms: a secondary breakdown and a latchup. Which type is dominant in p-channel and n-channel IGBTs depends on an absolute value of forward voltage mod V/sub CE/ mod . At moderately low mod V/sub CE/ mod , the p-channel IGBT is destroyed by secondary breakdown, and the n-channel IGBT, by latchup. This is due to the difference of a type of flowing carrier crossing a base-collector junction of wide base transistor and ionization rates of electrons and holes. >

Numerical analysis of short-circuit safe operating area for p-channel and n-channel IGBTs

A new 600 V vertical Insulated Gate Bipolar Transistor (IGBT) structure with monolithically integrated over-current, over-voltage, and over-temperature sensing and protecting functions has been developed to exploit an extremely excellent trade-off characteristic between an on-state voltage drop and turn-off time for the first time. This device can be easily made by the conventional IGBT fabrication process. An accurate and a real-time device temperature detection, as well as a high withstand capability against over-current and over-voltage conditions (short circuit immunity of 30 /spl mu/sec, clamped collector voltage of 640 V), have been achieved. Furthermore, an excellent trade-off characteristic of 1.40 V as an on-state voltage drop and of 0.18 /spl mu/sec as a fall time is also obtained. >

A new vertical IGBT structure with a monolithic over-current, over-voltage, and over-temperature sensing and protecting circuit

A new IGBT structure with a monolithic overcurrent sensing and protection circuit has been developed. The feature of this device is a novel integration of a sensing and protection circuit which consists of a sensing IGBT, lateral n-MOSFET, polycrystalline silicon diode and resistor with an IGBT structure. The conventional IGBT fabrication process is available to this device with only one more photomask. Comparison of not only a short circuit safe operating area but both a trade-off characteristics between an on-state voltage drop and a turn-off loss and reverse biased safe operating area with a conventional IGBT has been investigated. Since exhibiting a large short circuit safe operating area without deterioration of any other device characteristics, this device can be applied to not only a soft switching application like voltage resonant circuit but a hard switching application like snubberless inductive load circuit.

Noriyuki Iwamuro

Papers

IGBT History, State-of-the-Art, and Future Prospects

Insulated gate thyristor

Numerical analysis of short-circuit safe operating area for p-channel and n-channel IGBTs

A new vertical IGBT structure with a monolithic over-current, over-voltage, and over-temperature sensing and protecting circuit

A new IGBT with a monolithic over-current protection circuit