The
full form of IGBT is Insulated gate Bipolar Transistor. It is a three terminal
power semiconductor device basically used as an electronic switch which can
maintain high efficiency during fast switching. It has been utilized in many
recent appliances: Electric cars, trains, variable-frequency drives (VFDs),
variable speed refrigerators, air-conditioners, stereo systems with switching
amplifiers and even lamp ballasts and vacuum cleaners.
The
IGBT is a hybrid device obtained by the integration of a BJT and a MOSFET in a
Darlington
configuration. The IGBT allows a great reduction of conduction losses even for
high voltage rating (low on-state resistance), low power gate drive losses
(insulated grid) and it can switch today in of less than 100 ns, whereas only 3
μs about 20 years ago. In addition, the current density of IGBT is 20 times
larger as compared to MOSFET and 5 times as compared to BJT. The IGBT is,
basically, a horizontal channel and vertical current MOSFET cell (VDMOS),
except for the N+ Drain layer, which is substituted by a P+
layer
at the collector.
The
IGBT is a semiconductor device with four variable tiers (P-N-P-N) that are
handled by a metal-oxide-semiconductor (MOS) gate structure without resurgent
operation. This way of action was first introduced by Yamagami in his Japanese
patent S47-21739, which was filed in 1968. This method of action was initially
reported as an experiment in the lateral four layer device (SCR) by B.W. Scharf
and J.D. Plummer in 1978. This method of operation was also experimentally
revealed in vertical device in 1979 by B. J. Baliga. Plummer filed a patent
application for IGBT mode of operation in the four layer device (SCR) in 1978.
USP No.4199774 was issued in 1980 and B1 Re33209 was reissued in 1995 for the
IGBT mode operation in the four layer device (SCR).
An
identical device was invented by Hans W. Becke and Carl F. Wheatley for which
they filed a patent application in 1980, and which they referred to as
"power MOSFET with an anode region". This patent has been called
"the seminal patent of the insulated gate bipolar transistor."
Hands-on
devices susceptible of operating over an extended current extent were first
reported by Baliga et al. in 1982. An alike paper was also presented by
J.P. Russel et al. to IEEE Electron Device Letter in 1982. The applications for
the device were initially regarded by the power electronics community to be
severely restricted by its slow switching speed and latch-up of the parasitic
thyristor structure inherent within the device. However, it was demonstrated by
Baliga and also by A.M. Goodman et al. in 1983 that the switching speed could
be adjusted over a broad range by using electron irradiation. This was followed
by demonstration of operation of the device at elevated temperatures by Baliga
in 1985.
Complete
suppression of the parasitic thyristor action and the resultant non-latch-up
IGBT operation for the entire device operation range was achieved by A.
Nakagawa et al. in 1984. Today, IGBT modules are available with the capability
of handling over 1000-amperes and sustaining more than 5000-volts.
The
performance of IGBT advances gradually with the development of technology as it
is a fairly modern invention. In power applications, bipolar transistor has
already been replaced completely by IGBT; a power module is within reach in
which several IGBT devices are attached in parallel, making it compatible for
power levels up to few megawatts, which thrusts farther the limit at which
thyristors and GTOs turn out to be the only option. According to its working
principle, an IGBT is a bipolar transistor primarily, guided by a power MOSFET;
it has the benefits of being a minority carrier device (satisfactory
performance in the on-condition, even for high voltage apparatuses), with the high
input impedance of a MOSFET (a very small volume of power can operate it on or
off).
Nowadays,
IGBTs are extensively used in industrial, medical, consumer, transportation,
financial, aircraft and renewable power generation sectors of the economy.
This lead to increased ease, favor and standard of life for billions of
people all over the world. Over the last 20 years, the growing influence of the
advanced efficiency of IGBT-powered applications have been a total worth saving
of $ 2.7 Trillion for U.S. customers and $ 15.8 Trillion for global customers.
Besides this, the promoted effectiveness generated by IGBT-powered applications
has produced an aggregate diminution in carbon dioxide emissions by 35 Trillion
pounds in the United States and 78 Trillion pounds globally by the last 20
years. We can’t deny the role of IGBT to make a viable worldwide society with
uplifted living norms along with alleviating the environmental influence.
At
this moment, few manufacturers are the major product providers for the global
market of IGBT. Infineon (Formerly Eupec), Fuji Electric, Mitsubishi, Powerex,
Semikron, Toshiba etc companies are leading the IGBT world now.
