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‘By choosing the right combination of materials and processing methods, there is so much more that can be done with polymers in semiconductor lithography, packaging and shielding,’ state ³¢²¹³¾²úè°ù³Ù&²Ô²ú²õ±è;±¹²¹²Ô&²Ô²ú²õ±è;µþ°ù±ð±ð³¾±ð²Ô and Ruth Cardinaels. The experienced researchers aspire to use their vast knowledge of polymer processing to help improve future chips.

‘Recently, the Casimir Institute organized a lecture in collaboration with Fraunhofer IZM about heterogeneous integration, focusing on novel packaging methods for chips. The lecture addressed the lack of knowledge in the semiconductor industry regarding working with thermoplastic composites. Research on semiconductor technologies and on polymer processing can benefit greatly from each other, but so far, they have mostly been living in two separate worlds,’ says ³¢²¹³¾²úè°ù³Ù&²Ô²ú²õ±è;±¹²¹²Ô&²Ô²ú²õ±è;µþ°ù±ð±ð³¾±ð²Ô, associate professor in the Processing and Performance of Materials group at the Department of Mechanical Engineering.

Manipulate materials toward desired properties

Together with Ruth Cardinaels, part-time professor in the same group and professor in the Chemical Engineering department at KU Leuven, he has extensive knowledge about processing polymers to achieve specific properties. Cardinaels: â€˜Our focus is on manipulating polymer-based materials to achieve certain physical properties. We conduct experiments, run simulations, and build models to predict properties and optimize the manufacturing process. We are not chemists; we don’t tinker with the molecular composition of the material. Instead, we start from existing materials and optimize their structure by carefully developing the processing technique.’ 

The group works on a wide variety of materials. Van Breemen: â€˜For example, I have worked on polycarbonate and polypropylene, but I also had a project on cheese, which is essentially a biopolymer.’ ‘And I have executed projects on dielectric properties of polymer nanocomposites, but also on the optimal composition of croquettes,’ Cardinaels adds with a laugh. 

From cheese and croquettes to semiconductor chips

When it comes to chip-related projects, both researchers have just taken their first steps into the field. Cardinaels is involved in a project on washing away unexposed photoresist in optical lithography. ‘I must admit that until recently, I was not aware that polymers were that important for semiconductor lithography.’  

Van Breemen is involved in multiple semiconductor projects: â€˜For example, I am working on a small project with the group of Andrea Fiore in the Applied Physics and Science Education department. It involves adding a polymer to a photonic chip, which is intended to serve as a kind of adhesive layer. In another project, Van Breemen and Cardinaels are collaborating with a partner in the semiconductor industry on a nanocomposite polymer that can be used as an optical coating to make lenses focus different wavelengths in the same focal point. This can be used for applications in metrology or imaging.’ 

For Van Breemen and Cardinaels, such a project typically starts by determining the minimum requirements for a system. â€˜We create an initial wish list and prioritize it, and then start with simple conditions that we gradually make more complex. With the same chemical formulation, you can use different processing techniques to create different microstructures and, with that, entirely different thermal, mechanical, optical, and electrical properties. For example, very strong flow conditions can cause extreme orientation of conductive carbon nanotubes in the polymer, which can lead to excellent electrical conductivity in one direction and zero in another.’

Toward the ultimate predictive model

Van Breemen likes the way his field of research is constantly evolving toward new sectors and applications. ‘As a group, we’re interested in anything that contains polymers, ranging from food and thermoplastics to opto-electronic applications. Initially, I worked on the wear and tear of various thin films. Over the years, I gradually shifted toward UV hardening polymers, which are much used in the semiconductor industry, for example in packaging, in conductive connections, and for shielding against radiation or heat. Certain polymers are often used for historical reasons, but with our latest knowledge, there are much better alternatives.’ ‘It is the cross-pollination between different applications that makes our work so interesting,’ Cardinaels adds. ‘Ultimately, we want to incorporate the insights we gain from various use cases into a model that will allow us to predict which combinations of materials and processing methods lead to which properties.’ 

To get there, the polymer experts need to overcome some hurdles first. Van Breemen: â€˜Polymers nowadays have a bad reputation â€“ think PFAS and microplastics. Plus, many people think we know everything and are done, but with new processing techniques, so much more is possible.’ â€˜Take 3D printing. This allows us to create different properties at different locations in the material, creating new behaviors and functionalities. This development, often referred to as metamaterials or nanopatterning, holds a lot of potential,’ Cardinaels adds. 

Both researchers see ample opportunities for groundbreaking collaborations within the Casimir Institute. Cardinaels: ‘For the semiconductor field, it can be hard to grasp that knowledge we have gained from cheese and croquettes can be highly relevant for them. The institute can help create a mutual understanding of each other’s work, not only amongst ºÚÁϸ£ÀûÍø researchers from different departments, but also of what is happening in industry. A major advantage of Eindhoven is that it is situated in the Brainport region, and as ºÚÁϸ£ÀûÍø, we have strong connections with the many tech companies in the region. This network makes it easier to actually implement the latest research results in industrial practices.’  

Van Breemen ends with a heartfelt call to action: ‘Come by, let’s talk. You can do a lot more with polymers than you think. And whatever challenge you are facing with the functionality of your chip, can inspire us to come up with innovative solutions.’