GaN takes on SiC with imec breakthrough

Technology News | April 29, 2021

By Nick Flaherty

Automotive Power Management Materials & processes

Research lab imec in Belgium has demonstrated a breakthrough gallium nitride (GaN) process on 200mm wafer that can take on silicon carbide (SiC) in high power 1200V designs for the first time.

Working with German semiconductor equipment maker Aixtron, imec has grown thicker epitaxial GaN buffer layers for lateral transistors for 1200V applications on 200mm QST substrates, with a hard breakdown exceeding 1800V.

The key is the parts can be built on a CMOS-compatible process in high volume, low cost 200mm fabs, dramatically reducing the cost compared to SiC devices. imec is also looking at moving from lateral devices to a vertical structure will also reduce costs as more devics can be made on a single wafer. This has been the strategy of other GaN chip providers: CEO Interview: The next generation of power ICs

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GaN devices were previously only suitable up to 650V or 800V, and SiC was used for voltages above this in applications such as electric cars and solar panel inverters at 800v and 1200V.

“GaN can now become the technology of choice for a whole range of operating voltages from 20V to 1200V. Being processable on larger wafers in high-throughput CMOS fabs, power technology based on GaN offers a significant cost advantage compared to the intrinsically expensive SiC-based technology,” said Denis Marcon, Senior Business Development Manager at imec.

The key to the high breakdown voltage is the careful engineering of the complex epitaxial material stack in combination with the use of 200mm QST substrates that were developed in the IIAP programme with Qromis. These wafers have a thermal expansion that closely matches the thermal expansion of the GaN/AlGaN epitaxial layers, paving the way for thicker buffer layers for the higher voltage operation.

“The successful development of imec’s 1200V GaN-on-QST epi-technology into Aixtron’s MOCVD reactor is a next step in our collaboration with imec,” said Dr. Felix Grawert, CEO and President of Aixtron. “Having installed the G5+C at imec’s facilities, imec’s proprietary 200mm GaN-on-Si materials technology was qualified on the high-volume manufacturing platform, targeting for example high-voltage power switching and RF applications and enabling our customer to achieve a rapid production ramp-up by pre-validated available epi-recipes. With this new achievement, we will be able to jointly tap into new markets.”