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Research for GaN technologies, devices, packages and applications to address the challenges of the future GaN roadmap

Periodic Reporting for period 3 - UltimateGaN (Research for GaN technologies, devices, packages and applications to address the challenges of the future GaN roadmap)

Reporting period: 2021-05-01 to 2022-10-31

UltimateGaN, a highly ambitious ECSEL project, aligned 26 partners from 9 European countries to achieve significant improvement in digitizing the European industry by means of GaN Electronic Components and Systems being used in applications, information highways and data centers in order to overcome the challenges of today’s society. With a clear focus on the next generation of GaN technology, the consortium addressed six major objectives along and across the entire vertical value chain of power and RF electronics, focusing on research and innovation in the fields of technology, packaging, reliability and application:

• Research on vertical power GaN processes and devices pushing performance beyond current state-of-the-art
• Research on lateral GaN technologies and devices to achieve best in class power density and efficiency while optimizing cost vs. performance
• Bringing GaN on Silicon RF performance close to GaN on Silicon Carbide thus enabling an affordable 5G rollout
• Breaking the packaging limits – size, electrical and thermal constraints - for high performance GaN power products
• Close the reliability and defect density gap for most innovative GaN devices
• Demonstrate European leadership in high performance power electronics and RF application domains

In the course of UltimateGaN, valuable and innovative results were achieved and all initial objectives could be reached. The project thus enables highest efficiencies in the chosen applications and will lead to a significant reduction of the CO2 footprint of digitalisation, smart grids and smart mobility.
WP1 "Vertical Power GaN" investigated technologies for vertical GaN device manufacturing, a technology suited for high voltage applications. The focus was on the carrier substrate choice for reduced device production cost. Two technologies for manufacturable vertical devices on large scale diameter were investigated – Si substrates and QST® (engineered substrate with a poly-AIN core). For Si substrates we successfully could model the possibility of 10-12 µm thick drift layers on 200-mm-diameter. For GaN on QST® 12 µm could be already demonstrated and a full device-manufacturing circle with 8 µm+ stacks on 200 mm-diameter substrates was performed without wafer breakage. Both technologies still need further investigation.

WP2 "Benchmark Lateral Power GaN" aimed for or the next levels of performance and cost improvement for lateral GaN power technologies. Ultra-compact and best-in-class 100V and 600V normally-off GaN power HEMTs have been realized on 200mm Silicon substrates resulting in a substantial productivity increase compared to state-of-the-art 150mm technologies. We successfully developed the underlying 200mm GaN-on-Si epitaxial processes, including design optimization of reactor hardware and reached optimum 100V and 600V device designs for advanced interconnect and packaging schemes, allowed improved epitaxy as well as device processes, and ensured the matching of requirements and device performance for the different use cases.

WP3 "GaN on Silicon RF Break Through" went for a „GaN on Silicon RF Break Through” an area where after 20 years of research still a lack of performance limits the possible success. Based on an existing RF-GaN on Si technology as the baseline, a novel transistor concept was implemented to push the gain-performance (enabling higher efficiencies) beyond state-of-the art. The research focused on improving substrates, epi and transistor processing. The feasibility of a GaN on Si RF-transistor with characteristics close to GaN on SiC could be shown.

WP4 "Assembly and Packaging of high speed and high frequency GaN on Si devices" focused on harvesting the advantageous properties (increased power densities and high switching frequencies for low loss energy conversion) of GaN FETs, by achieving lowest parasitic impedance in the electronic package. For the applications in the use-cases, WP4 was able to provide plateable mold packages for lowest Rdson through customized laser treatment of the mold body´s surface. Furthermore, PCB embedded GaN realized with Central Core Embedding (CCE) allowed the production of miniaturized RF power amplifiers modules, outperforming surface mounted MCM SiPs. A System in Package for shortpulse LiDAR in ADAS, taking into account the special needs of the laser diodes, was developed using flip chip configurations.

WP5 "GaN Reliability and Defect Research" aligned forces on GaN reliability and defect research to analyze performance- and reliability mechanisms in advanced GaN devices along the full value chain from the development of new methodologies for reliability, to material-level analysis, from device-level investigation, to system-level evaluation. Research results are ready to be exploited by the partners, in the fields of advanced methodologies for reliability, of defect/reliability interpretation, and of reliability-oriented system design.

WP6 "GaN RF and Power Applications" was dedicated to reach benchmark achievements of GaN devices developed and to demonstrate different RF and power applications in 6 use-cases:
UC1: Rectifiers with GaN technology for telecom & data centers – demonstrator achieved 97.8 % efficiency
UC2: GaN power amplifiers for RF frontends for 5G and radar – 5G RF amplifier (Doherty) demonstrator measured with GaN-Si devices. Top-level efficiency of 45% was achieved with higher bandwidth.
UC3: Nano-Second-Pulsed-Laser Driver for LiDAR – demonstrated 40 A in less than 5 ns following a low parasitic inductance approach.
UC4: Battery Charger for PHEV/EV – achieved reliable demonstrators for contact on-board charger (high-efficient, high-power-density) and for a wireless battery charger with a peak efficiency of 96% (best available industrial systems between 90% and 93%).
UC5: Single-phase PV Inverter – resulted in a fully GaN 10kW single-phase photovoltaic inverter demonstrator based on new GaN modules (increased power-density, reduced cost of the system)
UC6: Isolated GaN power converters for native DC microgrids – demonstration of an integrated DC microgrid to interconnect different renewable energy sources (loads and energy storage systems).
In times of energy shortage being a threat for society it becomes ever more true that the only way to save energy is not to use it. UltimateGaN demonstrated efficiency gains through GaN devices in all applications – photovoltaic, communication and smart grid – just to mention the most relevant.
The average loss reduction in all investigated applications is about 25%: Only for server power supplies, this sums up for about 1% of efficiency increase, compared to state of the art. When efficiencies are multiplied, about 10 TWhs will be saved by the new technology.

To sum up, UltimateGaN
- achieved a new world record in efficiency for a commercially available (SoP early 2023) server power supply with 97.8%.
- The project showed a remarkable area reduction potential for the next Power-GaN generation.
- The partners demonstrated a novel concept of Multi-2DEG with clear impact on the long-term roadmap for Power-GaN – this is the door-opener for a wider market of energy-saving GaN devices.

After 3.5 years the envisioned impact of UltimateGaN becomes reality as market prediction is transferred into real available market data for GaN power devices with a market of $274,2M in 2022 and a further prediction of $2B in 2027 (YOLE on GaN Power, Report 2022).
WP3: Small signal gain MAG versus frequency
WP5: Example of database of defects in GaN
WP1: 200 mm GaN-on-QST®, with processed trench gate MOSFET devices
UltimateGaN project logo
WP6: RF and Power applications of the Use Cases
UltimateGaN final meeting
WP2: 600V pGaN HEMT wafer in 200mm
WP4: Plate layers