Imec Develops 200mm GaN-on-Si Wafers for Power Electronics

Imec, a research and innovation hub for nano-electronics and digital technology in Leuven, Belgium, announced that it has developed 200V and 650V normally-off/enhancement mode (e-mode) on 200mm/8-inch GaN-on-Silicon wafers. According to Imec, the GaN-on-Silicon wafers achieve a very low dynamic Ron dispersion (below 20 percent) and offer state-of-the-art performance and reproducibility. Also, stress tests have also revealed the good device reliability. Imec says that this new technology is ready for prototyping, customized low-volume production, and technology transfer.

With faster switching for power devices, higher breakdown voltage, and lower on-resistance than silicon, GaN technology can serve as an ideal material for advanced power electronic components.

Imec Technology Compatible with Silicon Fab Processing

The research center’s gold-free GaN-on-Si device technology is compatible with a silicon fab’s wafer handling and contamination requirements for processing. In the GaN device structure, the buffer layer accommodates the large lattice mismatch and the differences in thermal expansion coefficient between the AlGaN/GaN materials system and the Si substrate.

Imec reports that it developed a new patent pending buffer design that allows the growth of buffers qualified for 650 Volt on large diameter 200mm wafers. According to Imec, this new buffer, combined with the choice of thickness for the Si substrate and doping increases the GaN substrate yield on 200mm to competitive levels, thus, enabling low-cost production of GaN power devices.

Also, the research center says it optimized the cleaning and dielectric deposition conditions and extensively studied the field plate design (a common method for improving performance).

As a result, the devices exhibit dynamic Ron dispersion below 20% at up to 650 Volt across the full temperature range from 25°C to 150°C. This dispersion translates to virtually no change in the transistor on-state after switching from the off-state, a typical challenge for GaN technology.

Stefaan Decoutere, program director for GaN technology at imec said, “Next to enhancement mode power device switches, imec also provides lateral Schottky diodes for power switching applications. ”