IMEC, Europe’s leading independent nanoelectronics and nanotechnology research institute, has demonstrated the growth of low-sheet-resistivity AlGaN/GaN high-electron mobility transistors (HEMTs) on 150mm silicon (Si) wafers. The process paves the way to low-cost GaN power devices for high-efficiency/high-power systems beyond the silicon limits.
The high-quality AlGaN and GaN layers were grown in IMEC’s new 150mm metal-organic chemical vapor-phase epitaxy (MOVPE) system. This infrastructure extension allows IMEC to offer access to its AlGaN/GaN epiwafers in a service mode to laboratories and partner companies.
For the first time ever, excellent uniformity results have been obtained for the growth of HEMTs on 150mm Si wafers. HEMT structures with a sheet resistivity as low as 272±5 O/square and a standard deviation as small as 1.9% (edge excluded) have been demonstrated.
The process overcomes current problems associated with the growth of high-quality epitaxial GaN layers on Si. These problems result from the high lattice mismatch and the large difference in thermal expansion coefficient between Si and GaN. An AlGaN buffer layer has been successfully introduced to provide compressive stress in the top GaN layer. This, in combination with an IMEC proprietary in-situ Si3N4 passivation layer, results in superb HEMT devices on Si.
Due to the lack of commercially available GaN substrates, GaN heterostructures are nowadays grown mainly on sapphire and silicon carbide (SiC). Si is a very attractive alternative due to its very low cost compared to sapphire and SiC. Other benefits include the acceptable thermal conductivity of Si (half of that of SiC) and its availability in large quantities and large wafer sizes.
The high-quality epitaxial AlGaN and GaN layers were grown in IMEC’s new 150mm metal-organic chemical vapor-phase epitaxy Thomas Swan Close-Coupled Showerhead reactor (MOVPE) system, in the framework of an European Space Agency (ESA) project called Epi-GaN.
Marianne Germain, director of IMEC’s Efficient Power Program: “This reactor is a very valuable extension of our existing 3×2″ system, as it increases both growth capacity and wafer size (up to 150 mm). The infrastructural extension allows IMEC to offer access to its AlGaN/GaN epiwafers in a service mode to laboratories and partner companies involved for the development of their GaN device applications. The results proof the capability of IMEC to grow HEMT epiwafers with excellent quality, good uniformity and high reproducibility.”
Specifications on epiwafer characteristics available through this service can be obtained at IMEC on demand. AlGaN/GaN HEMT epiwafers can be grown on sapphire, SiC or Si substrates.
Gallium nitride (GaN) has outstanding capabilities for power, low-noise, high-frequency, high-temperature operations, even in harsh environment (radiation), extending considerably the application field of solid-state devices.
IMEC is a world-leading independent research center in nanoelectronics and nanotechnology. Its research focuses on the next generations of chips and systems, and on the enabling technologies for ambient intelligence. IMEC’s research bridges the gap between fundamental research at universities and technology development in industry. Its unique balance of processing and system know-how, intellectual property portfolio, state-of-the-art infrastructure and its strong network of companies, universities and research institutes worldwide position IMEC as a key partner for shaping technologies for future systems.
As an expansion of its wireless autonomous microsystems research, IMEC has created a legal entity in the Netherlands. Stichting IMEC Nederland runs activities at the Holst Centre, an independent R&D institute that develops generic technologies and technology platforms for autonomous wireless transducer solutions and systems-in-foil.
IMEC is headquartered in Leuven, Belgium, and has representatives in the US, China and Japan. Its staff of more than 1450 people includes more than 500 industrial residents and guest researchers. In 2005, its revenue was EUR 197 million.