Precursor chemists tailor precursor molecules
“I’m one of the first links in the chain,” says precursor chemist Timo Hatanpää. He innovates, designs, and synthesizes new precursors for atomic layer deposition (ALD) at the Thin Films and Nanostructured Materials research group of the Department of Chemistry, University of Helsinki.

Precursor synthesis and development are part of basic research aimed at developing processes for atomic layer deposition. The work is most often motivated by an actual application that relies on thin films

Films produced through atomic layer deposition are almost ubiquitously used in products manufactured by the electronics industry. This technology, developed 45 years ago by Tuomo Suntola in Finland, is based on chemical reactions that can be used to create coatings from different materials.

When a new atomic layer deposition process utilising new precursors is developed, it is possible that the process will eventually end up being employed by the industry for manufacturing consumer products. However, those who initially developed the precursors and the process may never get to know that

A record in patents

“Companies are not telling us what they are using in their manufacturing processes. Sometimes, we may find out these things by accident,” Hatanpää notes. That is not something Hatanpää seems to mind, as he is aware of his value. After all, he has already more than a dozen patents in his portfolio, as well as some 70 scientific publications – and, now, also a doctoral hat.

Hatanpää’s doctoral dissertation, approved in September, is an exception. For his article-based work, the researcher had chosen 10 articles published in scientific journals quite some time ago. “Why not put them to use? The more current topics are discussed by other younger doctoral candidates.”

Feedback received by the precursor chemist, however, originates close to him, that is in other materials chemistry specialists who try to use the synthesized precursors to grow thin films in the ALD research group at the University. Successes are celebrated within the research group, while the entire ALD community cheers when results are published in scientific articles.

“There are plenty of failures along the way, but we have also developed a number of well-functioning processes,” Hatanpää states modestly. “What I find the most pleasing is discovering a functional precursor and process.”

Hatanpää lists requirements that are vital to the precursors used in atomic layer deposition: volatility, thermal stability and reactivity with the other precursor used in the process. Hatanpää is tasked with designing the precursor molecules with which these requirements are met.

Hatanpää’s workplace is a synthesis laboratory. In his investigations on the structure and characteristics of the compounds he manufactures, Hatanpää is utilising a variety of research equipment owned by the Department of Chemistry, such as a thermogravimeter, various spectrometers and an X-ray diffractometer. On the basis of these measurements, the most promising compounds are selected for ALD testing, where their functionality is conclusively determined.

Research for businesses

“The connections between the discipline of materials chemistry at the University of Helsinki and the industry are close, thanks to a cooperation agreement concluded with ASM Microchemistry Oy, a company operating in the same facilities,” says Professor Mikko Ritala. This collaboration was already established more than 15 years ago.

When the company makes a request, precursor experiments are carried out by mutual consent. Usually, Hatanpää’s solid expertise is needed to assess and come up with sensible precursors.

Such new precursors are needed for manufacturing novel thin film materials and improving materials already in use.

“You might be looking for a reaction working at lower temperatures, or if dusting of the solid precursor poses a problem in the manufacturing process, you can develop and experiment with a liquid precursor,” says Hatanpää.