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Enhanced substrates and GaN pilot lines enabling compact power applications

Periodic Reporting for period 3 - PowerBase (Enhanced substrates and GaN pilot lines enabling compact power applications)

Reporting period: 2017-05-01 to 2018-06-30

PowerBase: Enhanced substrates and GaN pilot lines enabling compact power applications
Power Semiconductors are key drivers for the innovation capability of European industries, large and small, generating economic growth and supporting employment
PowerBase aims to setup and enhance power semiconductor manufacturing pilot lines in the area of wafer production and chip embedding in packages with special attention on compact power applications. Demonstrators and full-scale testing are essential building blocks of PowerBase meant to stepping up Europe's innovation capability by the development of technologies in the area of energy efficient systems. This will provide Europe with reinforced means to significantly raise its competitive edge across the economy and to address its key societal challenges. PowerBase aims to contribute to the industrial ambition of value creation in Europe and fully supports this vision by addressing key topics of both “Strategic Thrusts”, “Key applications”, “essential Technologies (capabilities)”.
Main goals of PowerBase (innovation action with focus on exploitation):
• Development of advanced carrier substrate technologies for improved GaN material quality and reliability for next generation GaN based power devices
• Setup of a qualified wide band gap GaN technology pilot line based on 200mm wafers for high performance normally off GaN power transistors including GaN-on-Silicon epitaxy with advanced process control, high manufacturing stability and yield
• Expanding the limits of today’s 300mm silicon based substrate materials for power semiconductors in two directions: First on the low ohmic substrates and second at high ohmic substrates by introduction of advanced doping materials and power device processes.
• Improving manufacturability in a high volume / high automated fab as being key for cost competitiveness: work on advanced automation
• Enhance system compatibility by introducing advanced packaging solutions out of a dedicated chip embedding pilot line
• Demonstrate results and reliability in leading compact power application domains
Project success:
• Development of next generation of energy efficient switches and prepared them for mass industrial use in communication servers, lighting and renewable systems, and many other applications
• Installed GaN pilot lines for volume production by 2018 ready to serve the high performance market
Objective 1: Innovation on advanced carrier wafer technologies for GaN devices (WP 1)
Fabrication of demonstrators on the different substrates and evaluate the merits of the concepts on device level and benchmarking with respect to the reference process has been fully met.
Several carriers were identified which offer benefits for GaN growth. Moreover, no current report in the literature has shown results on advanced carrier wafer technologies and we can thus claim that the results achieved in PowerBase are beyond state of the art.

Objective 2: Expand the limits in ON resistance of low ohmic power transistors (WP 2)
Improvement of stability and yield for the new 300mm very low resistance crystal growth process, enabling the process freeze for the final device qualification at Infineon. Substrate resistivity down to 1 mOhmcm were reached, and compared to 200mm a better thermal conductivity is realized. The 300mm-based low ohmic PowerMos transistor has shown superior matching with the 200mm state-of-the art device for voltage classes from 40V – 100V (reliability tests passed) - technology ready for commercialisation.

Objective 3: Provide reliability test methodologies and analysis tools for novel GaN power switches on advanced carrier substrates in new 3D integration (WP 6)
Succesful development of methodologies suitable for reliability evaluation in an industrial environment (evaluation of production-level GaN HEMT devices, identification of failure modes and mechanisms of PowerBase devices, development of reliability models)
• Methodology to assess yield loss minimizing test limits for high temperature operating life test (this was not available before PowerBase).
• Identification of leakage conduction mechanisms in conventional and engineered substrates
• Identification & Understanding of most dangerous failure modes and mechanisms of power GaN HEMTs: vertical drain-to-substrate time-dependent breakdown (TDDB), gate-stack time dependent breakdown, hot-electron degradation

Objective 4: Enable MtM solution for high variability (WP 4+5)
GaN packaging and assembly: Evaluation of different high thermal conductive mold compounds. Investigation of different levels of vacuum during molding process for process ability and void reduction. Development of pressure assisted Ag sintering including routine quality analysis methodology.
Heterogeneous 3D integration: Optimization/Integration of multiple single process steps of TSV- and optical filter technology in the 3D processing pilot line (Improved plasma etch and -cleaning processes, Pilot line production readiness of a TSV capping process)
Exploration of limits of wafer-level-molding technology to create sub-milimeter lens structures led to the production of demonstrator samples.

Objective 5: Setup a pilot line for normally-on and normally-off GaN power devices (WP3)
Full establishment of the pilot lines with corresponding processes, control concepts and electrical parameter tests for the manufacturing of pGaN normally-off power HEMTs in 150mm and normally-on Schottky RF power HEMTs in 200mm.
Process of fully integrated normally-off wafer lots in the industrial pilot line. Tested and packaged parts shipped to PowerBase partners for reliability testing and assembly in application demonstrators.
Evaluation of advanced substrates GaN-on-Si high-voltage (epitaxy grown on p+ Si substrates, corresponding wafers processed with full normally-off process in industrial pilot line).

Objective 6: Enhance the compliance of GaN in standard packages and modules (WP 5+4)
GaN process “pre-die” developed in the pilot line - installed in Regensburg (half-bridge device application demonstrator 2018)
Universal handler equipment concept was finished for future extension of the pilot line after PowerBase.
More than Moore 3D integration was demonstrated with the heterogeneous integration pilot line. The integration was shown on an active interposer design based on an existing optical sensor device.

Objective 7 & 8: Achieve benchmark size and significant improvement in energy management (WP 7)
Demonstrators developed, operating, performance tested - benefits and improvements evaluated for solar inverter, battery charger and power supplies for automation systems.
LED-lighting demonstrator based on PowerBase
Telcommunication application - high efficiency rectifier on the market, showing benchmark results in size and power efficiency under real field conditions
- PowerBase successfully developed the next generation of energy efficient switches and prepared them for mass industrial use in communication servers, lighting and renewable systems, and many other applications.
- PowerBase successfully installed GaN pilot lines for volume production by 2018 ready to serve the high performance market.
PowerBase applications are on the market proving reliability for the mass market. Stable and achievable volume production of GaN-Devices (reliable, good price performance ratioe) in and for Europe is available through the pilot-line.