200mm GaN-on-Si Wafers yield 650V dispersion free normally-off/e-mode power devices

June 13, 2017 // By Julien Happich
Claiming a world's first, research centre IMEC has developed 200V and 650V normally-off/enhancement mode (e-mode) switching power devices on 200mm GaN-on-Silicon wafers.

The power devices whose technology IMEC is ready to transfer and deliver for prototyping or customized low-volume production, achieve a very low dynamic R on dispersion below 20% up till 650 Volt over the full temperature range from 25°C to 150°C and state-of-the-art performance and reproducibility.

According to the researchers, stress tests have also shown a good device reliability.

IMEC’s GaN-on-Si device technology is Au-free and compatible with the wafer handling and contamination requirements for processing in a Si fab. A key component of the GaN device structure is the buffer layer, which is required to accommodate the large difference in lattice parameters and thermal expansion coefficient between the AlGaN/GaN materials system and the Si substrate.

IMEC achieved a breakthrough development in the buffer design (patent pending), allowing to grow buffers qualified for 650 Volt on large diameter 200mm wafers.

This, in combination with the choice of the Si substrate thickness and doping increased the GaN substrate yield on 200mm to competitive levels, enabling low-cost production of GaN power devices. Also, the cleaning and dielectric deposition conditions have been optimized, and the field plate design (a common technique for achieving performance improvement) has been extensively studied.

The very low dynamic R on dispersion means that there is almost no change in the transistor on-state after switching from the off-state, a challenge typical for GaN technology.

IMEC – www.imec.be