Gallium nitride (GaN) is now widely used in a variety of applications, including chargers and adapters for mobile phones where it delivers efficiency and power density benefits, as well as in other sectors such as automotive, data centres, LED drivers, renewable energy, consumer audio and phone handsets for example. Engineers have realised that GaN’s superior switching performance is suitable for countless applications, and they are growing increasingly confident in the ability of suppliers like Innoscience to deliver proven technology, rugged and qualified processes – not to mention massive capacity.
Innoscience is the world’s largest manufacturing company fully focused on 8-inch GaN-on-Si technology. From the very beginning, Innoscience management understood that for GaN technology to become ubiquitous in many markets, performance and reliability – whilst vital considerations – were only a starting point. Before GaN could become widely adopted, customers would have three additional key demands.
The first one is that GaN technology devices must be affordable, as the industry isn’t willing to pay a big premium. Secondly, a large manufacturing capacity is necessary in order to deliver large volumes and absorb demand fluctuations. And thirdly, customers require security of supply, allowing them to develop their products and systems using the new GaN devices safe in the knowledge there won’t be production discontinuations and shortages.
Innoscience executives understood that only by focusing on 8-inch GaN-on-Si technology, dramatically scaling-up GaN-on-Si device manufacturing and controlling its own production fabs, would it be possible to meet the requirements of the electronic industry (namely: price, volume and security of supply).
Let’s look at the technology Innoscience has developed together with its trusted international partners. Power semiconductor engineers demand devices that show a normally-off operation – i.e. no current conduction when the transistor’s gate is set at 0V. Since the natural form of GaN HEMTs (High Electron Mobility Transistors) is normally-on (so-called depletion mode), special drivers must be placed in a cascode package solutions to realize normally-off operation.
However, Innoscience’s GaN HEMTs are intrinsically normally-off (enhancement mode) devices. Normally-off operation is realized by growing a p-GaN layer on top of the AlGaN barrier, forming a Schottky contact with the p-GaN layer (Figure 1). This increases the potential in the channel at the equilibrium, resulting in normally-off/e-mode operation.
Figure 1: A p-GaN layer, grown on top of the AlGaN barrier, forms a Schottky contact with the p-GaN layer resulting in normally-off/e-mode operation.
Low specific RDS(on)
A key parameter for defining device performance is the specific RDS(on), the on-resistance per unit area. The lower the specific RDS(on), the smaller a device can be made, enabling more devices per wafer and lower device cost.
Innoscience developed a proprietary strain enhancement layer technology, which consists of the deposition of a specific layer after the gate stack definition. The stress modulation created by the strain enhancement layer induces additional piezoelectric polarizations which causes the 2DEG density to increase reducing the sheet resistance by 66%. Since the strain enhancement layer is deposited after the gate formation, it only affects the resistance in the access region and it does not impact other device parameters such as threshold and leakage etc.
Figure 2: Innoscience has developed a strain enhancement layer technology resulting in low RDS(on).
Therefore, Innoscience’s GaN-on-Si e-mode HEMTs show very low specific on-resistance. Because Innoscience has optimized both epitaxy as well as device process technology, the (dynamic) RDS(on) does not increase over the full temperature and voltage range, suiting it for power switching applications.
Figure 3: Innoscience’s GaN devices show no appreciable drift in RDS(on) over the full temperature and voltage range.
Today, Innoscience can produce more than 10,000 8-inch GaN-on-Si wafers every month; this is due to increase to 70,000 wafers per month by 2025. The first Innoscience fab is already qualified to ISO9001 and the IATF 16949:2016 certification for automotive use, and the GaN HEMTs are qualified to the JEDEC standard as well as Innoscience performs more advance reliability tests to test their devices.
Uniquely for a GaN company, Innoscience offers devices that cover low (30-150V) and high voltage (650V) range. Innoscience’s GaN HEMTs (InnoGaN) are available from 30-150V in chip scale packages (csp) measuring 2x2mm to 2.2×3.2mm with RDS(on) down as low as 5.5mΩ (typ). 650V parts in DFN and wafer scale feature RDS(on) levels as low as 106mΩ (typ). Innoscience GaN HEMTs are being used in USB-PD chargers up to 120W, and in LLC converters. They are to be found inside data centre power supply racks.
By combining world-class technology, state-of-the-art processing technology and the world’s largest 8-inch GaN-on-Si capacity, Innoscience is answering both engineering and commercial challenges, enabling designers working in all market sectors to benefit for the proven performance benefits with no cost penalty.
Innoscience is an Integrated Device Manufacturer (IDM) founded in December 2015 with main investment from CMBI, ARM, SK and CATL. With the development of new technologies, the electric power grid and power electronic systems across the world are undergoing a massive transformation. Our vision is to create an energy ecosystem with the most effective and low-cost Gallium-Nitride-on-Silicon (GaN-on-Si) power solutions. In November, 2017, Innoscience first established a mass production 8-inch wafer line for GaN-on-Si devices in Zhuhai. In order to fulfill the rapidly growing power demands, Innoscience has inaugurated a new facility in the Suzhou in September, 2020. As a cutting-edge GaN technology provider, Innoscience’s 1,400+ employees and over 300 R&D experts are dedicated to delivering high performance and high reliability GaN power devices that can be widely used in diverse applications including cloud computing, electric vehicles (EV) and automotive, portable devices, mobile phones, chargers and adapters. For more information, please visit http://www.innoscience.com.