Toshiba Electronic Devices & Storage Corporation has developed a 6500 V-rated trench-type second-generation Injection Enhanced Gate Transistor (IEGT) chip featuring enhanced turn-off capability and short-circuit robustness. The company has also commercialized a new 6500 V press-pack IEGT (PPI) incorporating the technology for use in high-voltage applications, including HVDC transmission systems, STATCOM installations, and industrial motor drives.

The new device increases the voltage rating from the conventional 4500 V class to 6500 V, enabling a reduction in the number of power semiconductor devices connected in series for a given output voltage. According to Toshiba, this contributes to simpler system architectures and more compact power conversion equipment.

The development comes as the deployment of renewable energy continues to expand worldwide, increasing the need for efficient long-distance power transmission and advanced grid stabilization technologies. Since power generation sites and energy consumption centers are often geographically separated, high-voltage direct current (HVDC) transmission systems are becoming increasingly important. At the same time, the adoption of static synchronous compensators (STATCOMs) is growing to support grid stability.

In these high-voltage power conversion systems, multiple semiconductor devices are typically connected in series. Increasing the voltage rating of individual devices reduces the number of required components, helping lower system complexity and equipment size.

Toshiba has previously mass-produced 4500 V-class press-pack IEGTs. However, achieving reliable operation at 6500 V requires maintaining sufficient turn-off capability and short-circuit performance under significantly higher voltage conditions. This challenge is closely linked to the precise control of carrier transport within the semiconductor structure. In addition, variations in breakdown voltage observed during bias testing represented another technical hurdle.

To address these challenges, Toshiba developed a new 6500 V IEGT chip featuring a shorted dummy cell structure in the cell region, eliminating floating regions that can cause unstable potential distribution. The company also optimized the mesa width within the current conduction region and introduced an N-barrier layer beneath the P-base layer responsible for carrier transport control.

These structural enhancements improve carrier distribution and current flow throughout the device, resulting in more uniform current distribution during turn-off operation. Toshiba stated that this enables stable operation with sufficient turn-off capability and short-circuit performance under high-voltage conditions. The company also confirmed an improved trade-off between conduction losses and switching losses.

In the termination region, Toshiba adopted a structure incorporating guard rings and a semi-insulating layer to distribute the electric field more effectively. This design enables breakdown voltages exceeding 6500 V. Additionally, optimization of the interface process between the semi-insulating layer and silicon suppresses breakdown voltage variations observed under bias stress conditions, contributing to more stable device characteristics.

The newly developed chip has undergone turn-off and short-circuit testing at a voltage of 4500 V, confirming its suitability for high-voltage power applications.

Based on this technology, Toshiba has commercialized the ST2000JXH35A, a 6500 V / 2000 A press-pack IEGT. In HVDC transmission systems, the use of 6500 V devices can reduce the number of series-connected semiconductor devices by approximately 33% compared with 4500 V solutions, contributing to lower system size and weight.

Toshiba stated that it will continue developing press-pack IEGT technologies for high-voltage power conversion applications while expanding its product portfolio to support the advancement of power transmission and energy infrastructure systems.

The technology was presented at PCIM Europe 2026, held in Nuremberg, Germany, from June 9 to 11, 2026.

Original – Toshiba