Urban Forsberg, senior associate professor at Linköping University, is holding a small, rectangular plate between his thumb and index finger. His fingertips get blacker with every little move.
“This is pure graphite. 99.9995 percent carbon. Quite pure, in other words. But not pure enough, as graphite still needs a protective surface for what we want it for,” he says.
So, what does this small graphite rectangle have to do with international politics? Well, graphite is an important component in semiconductor material production. For the past few years, semiconductor materials and the shortage of these have been in focus for the tech sector and international industry.
The COVID-19 pandemic changed a lot, and its aftermath is still noticeable in many respects, for instance in the manufacturing industry. The longer the pandemic lasted, the more unreliable semiconductor material transports to Europe became. This was due to closed factories and cancelled international deliveries, mainly from Asia. Many electronics-heavy industries are still affected by this, such as the car industry, the energy sector, health care and not least the communications sector.The inside of one of the CVD-machines that the PhD-students get to use for practice. Photo credit Magnus Johansson
And on top of that, more than half of the world’s semiconductor material is produced by one single factory in Taiwan, sometimes referred to as the world’s most important factory. Increased tension between Taiwan and China has however led to increasing concerns about semiconductor production, and should anything happen to the factory in the event of armed conflict, the world would be facing a monumental challenge.
The EU has therefore decided to double its world share of semiconductor production from 10 to 20 percent until the year 2030. This is also when it is estimated that the market will have doubled, which means that the 20 percent increase will be even greater in absolute numbers.
Chemical vapor deposition
For this to happen, the EU has issued a call for proposals totalling approximately SEK 93 billion. In return, industry will contribute a further SEK 158 billion. The call for proposals invited European companies to apply for grants for research, development and production. One of the 56 chosen companies is the German SGL Carbon. We will return to them later.
One step in the process of making semiconductor materials is the creation of extremely thin films of for instance silicon, gallium nitride or silicon carbide. This is done in large furnaces called CVD machines. CVD is an abbreviation for chemical vapor deposition.
But what about graphite? Several parts inside the machines, such as heating elements and substrate holders, are made from graphite. But when graphite is heated to a couple of thousand degrees it will be attacked by gases created in the furnace and release unwanted compounds – no matter how pure it is. The golden plate is graphite coated in tantalcarbide. Photo credit Magnus Johansson As these compounds may create defects and impurities that destroy the semiconductor material, a diffusion barrier has to be applied to protect the surface of the graphite so as to avoid this.
“The inside of a CVD machine is one of the cleanest environments on earth. An operating theatre is filthy in comparison,” says Urban Forsberg.
Working close to industry
Also the encapsulation of the graphite parts can be done in a CVD machine, and this is exactly what SGL Carbon does. Silicon carbide is one of the compounds they use as protective coating, and the components are then sold to the semiconductor industry. But it takes research to come up with an encapsulation that can withstand enormously high temperatures, is three-dimensional and can be produced at a reasonable cost.
Linköping University has collaborated with SGL Carbon before. It all started seven years ago, when the company realised that more advanced coatings were necessary to keep up with developments in the semiconductor industry. Their hunt for an academic collaboration partner begun.
“They googled: ‘Who is the best in the world when it comes to silicon carbide?’ and Linköping University and Professor Erik Janzén came up. Unfortunately, he passed away in 2017, but up until then he built a productive research environment working close to industry,” says Urban Forsberg, who has taken on this work.
As SGL Carbon has been awarded the EU grant, they can now, together with LiU, build a research environment with a new lab, a new CVD machine and a number of researchers who will work on the project for five more years. This collaboration has so far resulted in one PhD researcher, one postdoc, a number of articles and also patents.
This ultimately makes LiU an even more important partner to SGL Carbon’s research activities. But in spite of this work being commissioned by a private company, academic freedom has been safeguarded.
“It’s a balancing act. This is almost commissioned research, or at least research very close to industry, but we must apply academic standards to it. SGL understands this, as they have many former academics in leading positions who understand what it takes,” says Urban Forsberg.Urban Forsberg, senior associate professor at the division of Thin Film Physics in the Department of Physics, Chemistry and Biology. Photo credit Magnus Johansson
The project at Linköping University is financed by SGL Carbon for five years. Urban Forsberg continues:
“Research close to industry is frowned upon by some. But Erik Janzén, with a background in ABB, understood early on that in addition to funding from the Swedish Research Council, Vinnova and so on, you need partners in industry to achieve a critical mass. This research is very expensive, so you have to invest in the right things. There’s room for this research also at the university, and that’s important.”
Purity is key
The LiU researchers currently focus mostly on silicon carbide and tantalcarbide. But silicon carbide is limited to certain applications, and tantalcarbide is expensive. So the long-term goal for the project is to find new sustainable and financially viable coatings for the graphite components.
Purity is key in the manufacturing of semiconductors that are to become for example power components in electric cars, controlling the flow of electricity between different parts of the engine.
“Improving material quality and reducing production cost is important. However, the semiconductor industry is very tied to tradition and it’s difficult to introduce new materials. You have to show that it works over time,” says Urban Forsberg.
The new lab will be built in 2024. But because of long delivery times in the wake of the COVID-19 pandemic, there is no saying when all parts for the CVD machine will have arrived. But once it is in place it will be possible to coat whole prototype parts with new types of coatings and materials.
“What we make in our lab we can send to partners in exchange for the results they get when using the product in their machines. But it’s important to remember that we’re not running a factory, it’s a research lab.”
The black plate is pure graphite and the golden one is coated in tantalcarbide. Photo credit Magnus Johansson
Metals lead electricity whereas isolators, such as plastic and glass, do not. Semiconductors are in between. They are good enough at leading electricity, which opens up for many uses. Silicon, germanium and silicon carbide are some common semiconductor materials. By adding other compounds to the material (doping) it can become a semiconductor material used in electronics. Common semiconductor components include LEDs, transistors and chips.