Infineon Silicon Carbide MOSFET Technology

Infineon is one of the earliest manufacturers to explore silicon carbide (SiC) materials, with a 20-year history of mass-producing SiC devices.

They offer a range of products including SiC diodes, SiC MOSFETs, and SiC modules. During the process of transitioning from SiC material to SiC power semiconductors, reliability issues with the gate oxide layer inevitably arise

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The gate oxide layer, composed of SiO2, serves to provide insulation between the drain and source, while also enabling the formation of a reverse channel when the gate voltage exceeds the threshold voltage (Vgs.th).

The high energy bandgap of SiC material results in high tunneling current, which ultimately affects the reliability of the gate oxide layer. Prolonged operation of the SiC gate SiC/SiO2 interface leads to ion migration and high defect density in the channel region. To address this, it is necessary to increase the gate drive voltage or reduce the oxide layer thickness. However, increasing the gate drive voltage and reducing the oxide layer thickness also present reliability lifespan issues.

In 2015, Infineon proposed a vertical trench structure [1] that facilitates meeting performance requirements without compromising the reliability of the gate oxide layer, as shown in Figure 1. Infineon conducted a series of reliability experiments, such as HTGS, on SiC devices [2], demonstrating that this architecture can achieve a 20-year operational lifespan under +15V/+18V gate voltages and 150°C environments. This gives them the confidence to promote mass-market adoption [3].

Furthermore, through destructive testing of gate overvoltage stress, it can be observed that Infineon’s SiC devices exhibit exceptionally high robustness. In addition to considering gate reliability, Infineon’s SiC MOSFETs offer the following advantages: 1) high threshold voltage to prevent false triggering, 2) short-circuit capability, and 3) controllability of dv/dt. These unique characteristics make Infineon’s SiC MOSFETs more user-friendly.