T-series and U-series IGBT
Modules (600 V)
Seiji Momota
Syuuji Miyashita
Hiroki Wakimoto
1. Introduction
for the above new IGBT modules. This paper presents
these device techniques and the product series.
The IGBT (insulated gate bipolar transistor) mod-
ule is the most popular power device in power electron-
ics fields such as motor control applications. The
reason for the IGBT’s popularity is the market values
of its excellent reliability due to reduction of generated
loss and increase of withstand capability, etc., in
addition to the fact that it can be easily driven. The
600 V IGBT modules play an especially important role
as key devices in a wide market area including the
Japanese domestic market where 220 V industrial
power supplies are used and overseas such as in
Europe where 200 V public power supplies are used as
general-purpose power supplies.
Under these circumstances, Fuji Electric has also
been developing a 600 V IBGT module product series,
and has continued to improve their characteristics ever
since first developing the series in 1988. In 2001, the
development of thin wafer processing technology en-
abled NPT (non-punch through) structure to be applied
to 600 V devices. This made possible the development
of T-series IGBTs, having low switching loss and being
especially suitable for high frequency applications.
While development of NPT technology mainly
involved by development of the structure at the back of
the chip, improvements of the chip’s front structure
have also been implemented since 2002. By applying
trench-gate-structure, increase in channel density and
elimination of the unnecessary voltage-drop component
was achieved, thereby enabling the reduction of on-
state loss. This made the development of U-series
IGBTs successful, as the device having the smallest
loss among products of its class, and at present, we are
in the process of producing various rated current series
and sample modules.
2. T-series IGBT Modules
2.1 Features and challenges of T-series IGBT modules
The cell structure of an NPT-type IGBT and the
unit cell of PT (punch-through)-type device are shown
in Fig. 1. Their features are as follows:
(1) Since injection from the collector-side can be
suppressed, lifetime control is unnecessary and
the switching loss does not increase even at a high
temperature.
(2) Because the temperature dependence of output
characteristics is positive (the saturation voltage
increases at higher temperatures), these devices
are well suited for parallel applications.
(3) Withstand capability including load short-circuit
capacity are higher than those of a PT-type device.
(4) Use of an FZ (floating zone) wafer makes the price
cheap and the reliability high owing to its low
crystal defects.
The challenge is to establish a thin wafer process-
ing technique. It is important for NPT-type devices to
suppress saturation voltage while maintaining the
collector-emitter (CE) forward blocking voltage. This
Fig.1 Comparison of unit cell structures
G
E
G
E
n
-
n
-
n+
p+
C
p+
For the FWD (free wheeling diode) packed in IGBT
modules, enhanced soft-recovery characteristics as well
as decreased loss is demanded. These demands are not
only for the sake of preventing equipment malfunction,
but also to preventing possible ill effects of noise
emission on the surrounding equipment and on the
human body. To satisfy these requirements, FWDs
having a new structure were developed and adopted
C
(a) PT-type IGBT
(b) NPT-type IGBT
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Vol. 48 No. 4 FUJI ELECTRIC REVIEW