Street credibility: SiC MOSFETs engineered to meet real automotive requirements

Electric mobility is defined by key system-level requirements: range, performance, and long-term reliability under real-world conditions. These requirements converge in one of the most critical drivetrain components: the traction inverter. It must operate efficiently under dynamic loads, ensure stable performance throughout the vehicle’s lifetime, and meet strict robustness criteria. For original equipment manufacturers (OEMs), this means specific requirements for their semiconductor components.

Silicon carbide (SiC) MOSFETs have earned their place in this demanding environment. Until recently, however, they were primarily viable in high-performance electric vehicles, where the superior efficiency and thermal behavior of the material translate directly into a longer range, higher drivetrain performance, and more durable operation. With its third generation of SiC chips, Bosch is taking the next step. The goal is not just to improve the chips, but also to provide a solution tailored to automotive applications that will enable scalable electric mobility across all vehicle segments.

The outcome: SiC Gen 3 offers clear performance and application advantages over previous generations, including smaller chips, greater efficiency, and easier application into inverter systems. Gen 3 is notable not only for its technical advancement, but also for its consistent alignment with OEM requirements, which is achieved by focusing on direct customer feedback throughout the development process.

From customer insight to device architecture

As Gen 1 and Gen 2 SiC chips proved themselves in demanding automotive environments, Bosch’s development teams maintained a continuous dialogue with OEM customers. This ongoing discussion about real-world inverter operation revealed where further optimization would be most valuable: precise and controllable switching behavior, high short-circuit robustness, and predictable long-term performance – combined with solutions that are easy to integrate into inverter designs.

This prompted the development team to concentrate on specific architectural advances: switching losses were reduced by around 10 percent; short-circuit withstand capability was increased by around 10 percent; and a new shield implant was introduced that eliminates electric field stress on the gate oxide during off-state operation, improving long-term gate oxide reliability. Combined with a body diode optimized for soft recovery behavior across the full automotive temperature range of -40 °C to 200 °C, Gen 3 provides stable and predictable performance for high-volume automotive applications while reducing the complexity of inverter design and calibration. For a detailed look at the architectural advances of Gen 3 MOSFETs, check out this story.

A system-level development approach

Bosch’s approach to developing Gen 3 SiC MOSFETs stands out thanks to its system-level logic spanning the entire value chain, from semiconductor design to power module integration and complete inverter validation.

For Gen 3, our semiconductor development teams collaborated closely and continuously with Bosch’s in-house inverter engineers. Inverter specialists validated critical performance metrics, including switching behavior and short-circuit robustness, under realistic conditions. This early validation simultaneously improved the controllability of the devices in real inverter environments, making Gen 3 significantly easier for OEMs to integrate.

Cross-functional alignment with the manufacturing and quality teams was equally important. This alignment ensured that new architectural features could be integrated into established production processes without adding complexity. For example, the additional shield implant characteristic of Gen 3 was realized by reusing the existing hard mask from the trench etching process – a direct result of designing for manufacturability from the start.

A stronger cost and performance profile at system level

For OEMs, the value of a semiconductor generation is ultimately measured at the system level. The cost of power electronics is not solely determined by the price of components; it is also shaped by cooling requirements, design complexity, module footprint, and manufacturing efficiency. Gen 3 improves all of these parameters.

Reducing the specific on-resistance by 20 percent enables higher power density at the same chip size. Alternatively, it allows for smaller chip designs with equivalent performance. Both options translate into more cost-efficient module layouts. Finally, Gen 3 is manufactured exclusively on 200 mm wafers, which increases die yield per wafer and supports scalable, high-volume production. This helps reduce the price.

Taken together, these advances shift the economic equation for silicon carbide in automotive applications. The performance-to-cost ratio improves substantially, establishing Gen 3 as a viable option for not only premium and high-performance vehicles, but also mid-range platforms and high-volume segments.

Semiconductors engineered for the real world

Gen 3 SiC MOSFETs are the result of a development philosophy that prioritizes the application: what is required by the OEM, how does the inverter perform under real-world conditions, and how can semiconductor design address those requirements with precision and cost-effectiveness? Through continuous communication with customers, collaboration between the semiconductor design, inverter engineering, and manufacturing teams, and rigorous system-level validation, Bosch has developed a generation of chips that addresses the OEM’s need for enhanced performance, robustness, and improved system cost. This is what it means to be engineered for the real world.

Five good reasons for Bosch’s Gen 3 SiC MOSFETs

• Eliminated gate oxide stress in off-state operation: The new shield implant below the trench removes electric field stress from the gate oxide during the off-state, improving long-term reliability.
• 20 percent lower specific on-resistance: Reduced R_onA at the same power level enables smaller chip areas and provides direct cost advantages for OEM inverter and power module designs.
• Reduced switching losses by 10 percent: Improved capacitance characteristics result in faster voltage commutation and more efficient switching behavior.
• Enhanced short-circuit and parasitic turn-on robustness: The two-zone JFET region and high gate threshold voltage contribute to a wider and more robust operating window for demanding automotive applications.
• Higher power density through reduced die thickness: Reducing die thickness by 40 percent improves thermal conductivity and heat dissipation, enabling more compact module designs and increased power density.