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What is Soft Punch Through IGBT Technology?

SPT IGBT forward characteristics

The latest Trench Fine Pattern (TFP) IGBT chips are built on the developments in Soft Punch Through (SPT) chip design, delivering the lowest losses ever for IGBT switches. The progression of this technology is leading the way to a better IGBT.

SPT Technology

SPT technology features thinner silicon, combined with a highly-rugged planar cell-design platform. The technology substantially increases the cell latch-up immunity, achieving lower losses. IGBT and diode chips with SPT planar technology therefore have higher switching performance and reliability.

SPT+ and SPT++ Technology

IGBTs using Hitachi Energy’s advanced SPT+ technology benefit from a conduction loss reduction of 20 to 30% compared to earlier SPT technology.

Figure 1 shows the basic difference between SPT+ and SPT++. By introducing an N-enhancement layer surrounding the channel-P-well, the plasma concentration is improved on the emitter side, lowering the on-state losses. The introduction of the SPT++ allowed the N-enhancement layer profile to be optimised further with the main goal to make another step in conduction loss improvement. Together with thinner silicon, a reduction in VCE SAT of half a volt was possible.

Soft punch through planar profile

Figure 1 SPT+ planar IGBT enhanced carrier profile

Hitachi Energy’s SPT+ IGBT technology permitted the company to establish a new technology curve benchmark over the whole IGBT voltage range from 1200 V to 6500 V.

SPT technology VCE SAT

Figure 2 Vce sat for different IGBT cell technologies on SPT silicon at 125 °C

IGBT Characteristics and Losses

Figure 3 shows the on-state curves of the 6.5 kV SPT+ IGBT. The typical on-state voltage drop (VCE,on) at nominal current and Tj =125 °C is 4.0 V. The SPT+ IGBT shows a positive temperature coefficient of VCE,on, already starting at low currents. This enables a good current sharing capability between the individual chips in the module.

SPT IGBT forward characteristics

Figure 3 Forward characteristics of the 6.5 kV SPT+ IGBT

Figure 4 shows the turn-off waveforms of the 6.5 kV HiPak module measured under nominal conditions ie, at 750 A and 3600 V. Under these conditions, the fully integrated turn-off losses of the module amount to 5.2 J.

SPT IGBT turn-off waveforms

Figure 4 6.5 kV SPT+ IGBT turn-off under nominal conditions measured at module level

TFP Technology

IGBT chips based on a Trench Fine Pattern (TFP) technology build on the SPT++ N-enhancement technology by adding a very compact fine patterned trench cell to improve the conduction and switching losses by more than 30% compared to the SPT++ technology.

Hitachi Energy’s range of SPT+, SPT++ and TFP IGBT and diode chips is available at 1200 and 1700 V, ranging from 50 to 300 A. Contact us to find out more about Soft Punch Through technology and discuss your requirements.

Useful Links

IGBT and diode modules
Hitachi Energy Power Semiconductors

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