Silicon carbide powering the energy revolution

"The display in my electric car didn't work this morning; there was probably something wrong with a semiconductor," Ascatron co-founder Christian Vieider says with a chuckle. 

Semiconductors are found in almost all electronics, in everything from refrigerators to cars. Silicon is the most common semiconductor material. Over two thousand silicon chips are required to enable the energy conversion in an electric car. As more features are introduced in vehicles, such as self-driving, even greater numbers of chips in more energy-efficient materials are needed. The next generation of silicon carbide semiconductors consumes less energy and has more transistors. 

Christian walks up the spiral staircase at Isafjordsgatan 22 in Kista. It leads to the Electrum lab, a test bed for nanoconductor and semiconductor technology operated by RISE in close collaboration with KTH (Royal Institute of Technology). This is where Ascatron's journey began ten years ago. At the time, Christian was working with the commercialization of RISE technology for energy-efficient silicon carbide. 

In 2011, Ascatron was formed by four employees from Acreo, now part of RISE Research Institutes of Sweden. Ascatron has been owned by II-VI (two-six) since 2020, and they now mainly manufacture silicon carbide wafers, a key technology in many power electronics applications. 

Commercialization of silicon carbide – from material development to components 

Christan turns in towards the corridor on the fifth floor. There, Ascatron and RISE researchers are working side by side in the Electrum lab. He walks into a meeting room and sits down. 

At the Electrum lab, Christian and the research team manufacture the epitaxial layer of the semiconductor, that is, the active layer in the component that determines how much voltage it can withstand. This technology laid the foundation for Ascatron, which was spun off from RISE in 2011.  

"The market was ready," says Christian, leaning back in his chair. "There was a demand for silicon carbide, and RISE already had customers buying this semiconductor material. The initial idea was to build a factory to scale up the manufacturing technology and then form a company. The next step was to find investors." 

Ascatron was early in creating larger epitaxial wafers and went from making wafers of 100 millimeters to wafers of 150 millimeters. It enabled twice as many components per wafer, and the company gained an advantageous position in the market. Ascatron initiated collaboration with major component manufacturers, such as ABB.  

"We had come as far as we could with material manufacturing, and in 2015, we started developing silicon carbide components on our epitaxial wafer," continues Christian. "The components should not only be efficient and have as little energy loss as possible in their electricity conversion, but they also have to be reliable and robust."  

Silicon carbide – an enabler for the fossil-free society 

Society's transition from fossil fuels to electricity is expected to create a sharp rise in electricity use, according to the Swedish Energy Agency, forecasting that electricity use will double by 2050. But to achieve a fossil-free society, energy also needs to be used efficiently, which is why Sweden aims to reach 50 percent more efficient energy use by 2030. 

"The electrification of our society will create new demands on what power electronics need to be able to handle," says Christian. "We are facing a huge challenge in the energy revolution now underway. If Sweden is to increase its electricity production, this type of component is needed to convert the electricity." 

Conversion of electricity causes losses of up to ten percent. When the power from an electrical outlet reaches, for example, an electric car, about ten percent of the energy has already been lost. But components built with the next generation semiconductor materials are more energy efficient. 

"With silicon carbide, you save power and remove about two-thirds of the energy loss compared to silicon chips," he explains. "This means, for example, that you can drive ten to twenty percent longer with your electric car or save the same amount on battery usage. It makes our technology very attractive to the electric car market."  

Electronics giant II-VI invests in Ascatron's silicon carbide technology 

"After a decade, we had come as far as we could with our own development operations," says Christian. "We needed a long-term owner to develop commercial products. It also had to be an established player to be of interest to potential customers such as Volvo or Volkswagen."  

Ascatron's advanced epitaxy wafers in silicon carbide attracted the interest of US semiconductor manufacturer II-VI. The electric car market had taken off. With the acquisition of Ascatron in 2020, II-VI could lift itself into the value chain and offer wafers and components in silicon carbide to manufacturers of electric vehicles.  

"What distinguishes our technology is that we have developed materials that can withstand really high voltages," Christian says. "With this technology, you can develop components that can handle over ten kilovolts, which makes us unique in the market."  

II-VI now has 22 employees in Kista who work with silicon carbide power components and epitaxy production as part of the company's development department. The next step is to continue growing. 

"We will scale up our production in Kista, and we will be able to move from pilot production to delivering on a large scale to our customers. We are now determining where the volume production will be based, but I hope some will be in Sweden, and we can create more jobs here."  

II-VI collaboration with RISE at the Electrum lab 

The fluorescent tubes cast a cold light on the computer screens, microscopes, and machines that line the walls of the Electrum Lab's 1,300 square meter cleanroom. The equipment is used to grow the epitaxial layer of the semiconductor wafers and to process components. Bright yellow pillars and an azure blue epitaxy reactor break with the white and metal grey ISO-certified cleanroom environment. The international standard ensures high quality for the industrial production of semiconductor materials. II-VI collaborates with RISE and KTH experts, clad in ice blue overalls. The protective clothing ensures that the clean manufacturing environment never exceeds ten thousand particles per cubic meter. It can be compared to a typical office with an equivalent volume of millions of particles. 

The power electronics lab, run by RISE, is one floor above the cleanroom. Here, II-VI tests its prototypes with the support of experts from RISE for testing and electrical characterization of its power electronics components. 

After the processed wafer has been cut down into chips, the pieces are encapsulated in, for example, metal oxide semiconductor field effect transistors (MOSFET). The experts test the transistors to measure the properties of the components and how well they work when under load. Klas Brinkfeldt is a unit manager at RISE and is responsible for the tests: 

"We provide expertise in the entire chain, from manufacturing and characterizing components to reliability tests, simulations, and material analysis," says Klas. "We're unique in Sweden in being able to offer a complete package and are thus helping with the development of the next generation of power electronics systems."      

RISE's long-term development of wafer manufacturing and fault analysis is now further accelerating in an extended collaborative agreement with II-VI. 

"We hope that we will have even closer collaboration with II-VI in the development and testing of the next-generation silicon carbide components," continues Klas. "We also see that it can create rings in the water and strengthen the entire ecosystem in Kista, thus helping to provide a larger arena for fault analysis of electronic components."  

Christian Vieider explains that collaboration with RISE has been essential for the company's success: 

"The collaboration with RISE has been a crucial success factor for us as our technology is based on 20 years of research at RISE. Access to customers, expertise, and equipment helped us to enter the market quickly."  

"The development of functional and reliable components based on new semiconductor materials is important for us in being able to conserve energy in the power electronics systems of the future," says Klas Brinkfeldt. "New materials such as silicon carbide require in-depth knowledge and new building methods. It will change the electronics industry and how we design, build, and produce wafers and circuits." 

RISE, II-VI, and the South Korean research Institute KATECH (Korea Automotive Technology Institute) have initiated research collaboration in semiconductor technology. The project will increase the efficiency of electric vehicles' power electronics systems.  

"We will manufacture components based on our fundamental technology and jointly design them with RISE," says Christian Vieider. "In the project, we will receive direct feedback from an end customer about how our components work in their application. This collaborative arrangement is invaluable in developing better products." 

Possibilities for the EU's independent semiconductor production 

Since 2021, there has been a shortage of semiconductors, which has crippled the production of electronic products, not least among electric vehicle manufacturers. The semiconductor shortage is expected to ease, but forecasts indicate that the problem will continue for years. The European Commission presented the European Chips Act, a proposal for measures to secure the European innovation and production capacity of semiconductors. 

"It is essential for Europe to become independent in semiconductor production," says Christian. "The production is knowledge-intensive. An example of this is that half of our staff are doctoral researchers. We have a high level of expertise in Europe, which creates good conditions for a European semiconductor manufacturing industry, and our operations can contribute to local silicon carbide production. This morning, my electric car didn't work, probably because there was something wrong with a semiconductor. This tells me the important role semiconductors play in our everyday lives."