imec announces first power devices on 200mm cmos compatible GaN on Si

With these wafers, functional GaN metal insulator semiconductor HEMTs (MISHEMTs) were processed using standard cmos tools. According to imec, the wafers are a major breakthrough in the cost effective production of power devices in high productivity 200mm fabs. GaN's performance is beyond what is possible with silicon and by using 200mm wafers, brings processing in reach of regular high productivity 200mm fabs. This enables cost reductions compared to processing smaller wafers on dedicated processing lines. imec recently succeeded in producing 200mm GaN-on-Si wafers with crack free surfaces and a bow of less than 50µm. The wafers were made using an advanced MOCVD system from Applied Materials. The power devices can be fabricated with processes compatible with standard cmos processes and tools. Imec proved this by processing its GaN-on-Si wafers using standard cmos tools, yielding functional GaN MISHEMTs. All equipment was verified for its capability to handle the wafers and required only minimal adjustments in software and hardware. Conventionally, gold is used for ohmic contacts and gate structures in power devices, but it makes GaN processing incompatible with conventional cmos processing. To overcome this, imec based the ohmic contact formation on an Au-free metallisation system and modified the Schottky gate to a gate dielectric based gold free metal insulator semiconductor structure. According to imec, this introduction of the MISHEMT structure had the added advantage of reducing the high leakage current of conventional HEMTs. Caption: Imec processes first power devices on 200mm CMOS-compatible GaN-on-Si