Novel 600-V trench high-conductivity IGBT (trench HiGT) with short-circuit capability

Emitter
Side
Collector Side
A
.*
c -
1 TrenchHiGT
. . I
E
? i
3
0
C
- -=
L?
Conventional Trench IGBT
Depth
Fig. 3 Hole concentration at different cross section lines. saturation current by discovering the IGBT scalingrulel). Moreover, the planer HiGT had drastically lower on-state voltage, keeping saturation current low, by placing a hall barrier around the p-channel region. This development increased the excess camer stored in it2).Our new trench HiGT is based on the HiGT concept, which has a lower on-state voltage and a suppressed saturation current with a tough short circuit capability. Figure 2 @) shows the our trench HiGT with punchthrough structure. It has a narrow emitter region, a wide p-floating region and a trench gate placed at its end. The figure also shows the hole density distribution, and the black lines represent the hole current flows.
Introduction
I
Fine Pattern IGBT (Conventional Trench IGBT)
Collector-Emitter Voltage (VI Fig. 1 Basic concept of HiGT
HiGT concept
Figure 1 shows the basic concept of our HiGT1)2). The conventional IGBT (planer IGBT) offers lower saturation current. However, it also has t h e
IGBTs which are being developed as the nextgeneration IGBTs. Although the trench IGBT offers
h e disadvantage of higher on-state voltage. Although t
fine-pattern IGBT (conventional trench IGBT) offers the advantage of low on-state voltage, it has the disadvantage of high saturation current. In contrast, our HiGT has both a lower on-state voltage and a suppressed saturation current. This results in low power dissipation and high short-circuit capability. Therefore, this HiGT does not need an additional protection circuit to reduce saturation current. Using the HiGT concept, we have been continuously developing high performance IGBTs. With the planer IGBT, we achieved low power dissipation and low 417
A B
(b) Trench HiGT
Experimental Results
Fig. 2 Hole distribution.
Figure 4 shows a photograph of the trench HiGT chip, The rated current is 12 A at 200 Alcm2.
/Gate,
Emitter
Figure 3 shows the hole concentrations at cross sections A, B, and C from figure 2 . In the conventional trench IGBT, the hole concentration is lowest at the shallowest depth, and line C decreases gradually from the collector to the emitter. In the trench HiGT, the concentration at cross section B also decreases gradually, contrary to previous reports3H). At cross section A, near the floating-p layer, the hole concentration is higher. The electrons are injected from the trench gate wall of the
the advantage of low on-state voltage, it also has the
disadvantage of not having the short-circuit capability of the planer IGBT. To overcome this disadvantage, we have previously proposed an HiGP) with a plane gate structure, a low on-state voltage, and a low saturation current. In this paper, we describe a 600-V high-conductivity IGBT (trench HiGT) with a trench gate structure that has a lower on-state voltage than a conventional trench IGBT and a better short-circuit capability with no additional protection circuits.
K.Oyama,Y.Kohno, J. Sakano, J. Uruno,I)K. Ishizaka, z)D.Kawase and M. Mori
Hitachi Research LaboratoIy, Hitachi L t d . 7-1-1 Omika-cho Hitachi-shi Ibaraki-ken 3 19-1292, Japan. Phone: +81-294-52-7592, Fax: +81-294-52-7949, E-mail: koyama@hrl.hitachi.co.jp 1)h4ulti-PurposeSemiconductor Business Div., Hitachi Ltd. 2Bower& Industrial Systems Div., Hitachi Ltd.
ate
I
(a) Conventional trench IGBT
c
wii Emitter
floating p-layer side, that is activated by hole current potential flowing from the floating-p layer. This provides the high conductivity of the trench HiGT.
55
voltage (1.55 V) than that of the trench IGBT, with saturation current under 842 A/cm2 This level is the same as that of the planer IGBT. This low saturation current allows the trench HiGT to have a short-circuit capability of 10 p s without a protection circuit, as shown
Abstract
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This paper describes new 600-V trench highconductivity IGBTs (trench HiGTs) that have lower onstate voltages of 1.42 and 1.55 V at 200 NcmZ and tough short-circuit capabilities of 5 and 10 LL s, respectively. These HiGT have a better trade-off between turn-off losses and on-state voltages than conventional trench IGBTs, even better than planar IGBTs. They also offer a lower reverse transfer capacitances (-5PA) than the planar IGBT. The input capacitance obtained were lower (-30% to -60%) than that of a conventional trench IGBT.