Vertical Nanowire Transistor Technology from Lund
Transistors based on nanowires handle higher frequencies and are more energy efficient than today’s CMOS components. This technology, first commercialized by NordAmps, a spinout of University of Lund, can be integrated into silicon CMOS processes. The company announced it received additional seed capital in December 2019. The funding will go primarily toward the development of two prototype circuits,one LNA and one PA design with relatively simple topology, targeted for 5G applications. The circuits will be completed this year.
“We conducted discussions with potential customers, especially semiconductor manufacturers and 5G technology providers. It is also conceivable that those who manufacture process equipment for semiconductor manufacturing would become customers as well,” said Lars Tilly, CEO and co-founder of NordAmps.
Development of the NordAmps Transistor
The transistors were developed within the framework of the three-year EU project, Insight, which was completed in the summer of 2019. The work was carried out by Professor Lars-Erik Wernersson’s group in Lund, together with colleagues in Europe. The team developed theoretical models for the transistors and manufactured functional components.
This project was so successful that a second project, Sequence, received funding of approximately SEK 50 million for another three years. Funding from Vinnova’s program, Smarter Electronic Systems, was also awarded to NordAmps and Lund University to verify manufacturability of transistors.
“The nanowires are made of indium gallium arsenide (InGaAs) a III-V material, which means the electron mobility is significantly higher than that of silicon, which leads to faster transistors” said Prof. Wernersson.
Just as for CMOS processes, channel lengths and associated scaling of nanowire dimensions can gradually decrease as well. Today they are around 100nm long, but the researchers have shown gate length as short as 20nm.
“The nanowire forms vertical channels. The gate is wound all around the nanowire, which makes it possible to control the current from all directions and thus obtain a much higher gain and transconductance,” explained Tilly.
The transistors work for applications of at least 100 GHz. The initial products include a low noise amplifier for 28 GHz and a power amplifier with an output power of 20 dB. These are targeted for amplifiers and other RF blocks for high-speed 5G and eventually also 6G products.
“At this stage, it’s not about getting the world’s highest speed but showing that the components work in a predictable and reproducible way,” added Tilly. “The next step will be to start joint development projects with customers in the coming one to two years.”
The long-term plan calls for developing a transistor that can also be used in high performance digital logic. The company has the highest level of maturity with N-transistors, but for digital logic, P-transistors are also under development. However, NordAmps has no plans to become a component supplier. The idea is to develop models of the transistor and a recipe for manufacturing. The former idea includes design and layout libraries linked to commercial EDA tools. This allows potential customers to design, for example, amplifiers based on the transistors. The latter is a prerequisite for manufacturing circuits.
“It is possible to grow the nanowires directly on silicon, which is a big advantage. By means of ordinary lithographic processes, you can define surfaces with nanowires exactly where you want them in the same way as you make today’s CMOS transistors,” noted Prof. Wernersson. “Nanowire transistors made of III-V material are included in the ITRS roadmap for 2025.
NordAmps has its own patents and patent applications for the nanowire transistor. In addition, Lund researchers, including Professor Lars Samuelsson, hold many basic patents on nanowire technology.
“We are well-positioned in the market,” said Wernersson. “The company currently has five employees, with plans to hire another. With this first external financing, we can step on the gas properly.”