No, these silicon wafers are not a truly collaborative product: at up to 40 µm, many wafers are thinner than a hair, have a diameter of 150 to 300 mm and are highly fragile. To turn these delicate silver wafers, which together can be worth the value of a mid-range car per protective cassette, into chips, they have to go through up to 1,200 process steps. And they have to be transported to a different automated processing station each time. A clear case for the use of robots.

At the Infineon site in Villach, power semiconductors of the kind used in cars, smartphones, refrigerators, server farms and locomotive drive units are produced. Infineon Austria, a subsidiary of the German Infineon Technologies AG, delivered 8.45 billion chips in the last 2020 financial year and generated a turnover of 3.1 billion euros. Pure future technology, which is also reflected in the research expenditure of 498 million euros, which makes the company one of the strongest research companies in Austria.

Extreme demands on cleanliness

In Hall 17 of the Villach plant, Infineon produces chips on the sensitive thin wafers in a Category 1 clean room environment, which means that no more than one dust particle is allowed in 28 liters of air. This is significantly less than is permitted in an operating theater. For comparison: in mountain air, which is considered to be particularly clean, there are around 100,000 particles buzzing around in such a volume. For employees, this means Access only in special, bright white full-body protective suits via a special airlock. Skin and hair must be completely covered so that no flakes can penetrate to the outside. Only a small viewing slit remains free. Laptops and other technical devices must be meticulously cleaned beforehand. Even pens and the sheets of paper for notes are specially manufactured to be particle-free.

"With these extremely sensitive production conditions for our thin wafers, we have to think very carefully about which transport technology we use here," explains Martin Moser, Team Leader Automation in the AMHS (Automated Material Handling System) department at Infineon Technologies Austria in Villach. "As various mobile units and people are always on the move in wafer production, only systems that are designed to be extremely sensitive for safe interaction between people and machines can be considered for use with robots. And without any protective fencing."

Mobile robots in semiconductor production

"In our search for this, we became aware of Kuka's lightweight robots at Automatica," reports the development engineer. Making them fit for the very special requirements in the cleanroom in accordance with ISO3 was an extremely intensive learning process in which the automation experts from Infineon worked hand in hand with their system partners. In addition to Kuka, these were primarily experts from Mechatronic Systemtechnik for the assembly, cabling and setup in production, as well as the programmers from Micado Automation for the system control.

"At the time, there was no blueprint for us for the mobile use of robots in semiconductor production. Together, we tailored the systems precisely to our needs. That was real pioneering work, both for us and for Kuka," reports Moser. This included making the lightweight robots cleanroom-compatible. This was still "uncharted territory" for the Kuka robots. "The constructive, solution-oriented cooperation of all those involved has contributed significantly to the fact that we now have an ideal transport solution for our automated chip production," says Moser.

Today, 17 LBR iiwa CR cleanroom robots are at work in several cleanrooms - around the clock, 365 days a year. "They are extremely agile, can handle payloads of up to 14 kg, work without vibrations and carry out work with millimeter precision with their gripper, even in the tightest of spaces," says Moser, explaining the advantages of the "Robis". In particular, their additional seventh axis allows them to perform sensitive and angled movements that are not possible with "conventional" 6-axis robots.

Positioning accurate to the millimeter

They quietly transport black cassettes full of valuable silicon wafers to the individual processing steps, feed them into the respective processing chambers with millimetre precision and then pick them up again. The mobile placement robots work closely with the Overhead Hoist Transport System, OHT for short. Suspended on rails under the almost 5 m high ceiling, the transport boxes float to the individual stations, where they are lowered using a belt hoist mechanism. There, they are picked up by one of the LBR iiwa robots according to the production algorithm and transported to the next processing step.

"Right from the start, we wanted a tailor-made solution for our production in Villach. Nothing else was an option for us," explains Martin Moser. "We therefore took on the integration of the systems ourselves. The direct exchange with the Kuka developers was very important to us - especially with regard to how we set up the overall system and how it continues to 'learn' afterwards."

Between feasible and necessary

As part of Martin Moser's team, Lisa Ebner has been involved in the integration of robots into the automated wafer production process from the very beginning. She has been part of the company for seven years and is the expert responsible for the placement systems. Lisa Ebner is a real fan of the mobile robots: "When I saw the LBR iiwa for the first time, back then as an operator, I was totally fascinated: I could have spent hours looking at the smooth, harmonious movements - a pure technical delight."

Ebner, an automation expert, is also studying mechatronics, systems engineering and management at the same time. She is constantly on the move in the production aisles, checking the systems at the control station and looking for further ways to perfect production. "When it comes to optimization, we have to find the right balance between what is technically and physically possible and what makes sense for our production purposes. The closer we get to 100% perfection, the greater the complexity and the number of interfaces. We always have to find the right balance for economical production."

Learning progress for the future of semiconductors

The automation team in Villach is clearly on the right track. "Everything we are learning now is taking us further - to the next level of automation in semiconductor production," says Bernd Steiner, Production Manager at Infineon Austria in Villach.

And time is pressing in Carinthia, as the shell of a new, fully automated chip factory is already standing next to the existing production halls. Infineon has big plans: the company is investing €1.6 billion in its Villach site, making it the largest private investment in Austria. Fully automated production of power semiconductors is set to begin here at the end of 2021. "Our aim is to deliver power precisely where it is needed in the smart factory," explains Steiner. "For the energy-saving chips of tomorrow, which are used in many everyday applications such as smartphones, household appliances and cars, but also in data servers, medical devices, solar and industrial systems. So that they make our lives easier, safer and more environmentally friendly."