Photo: Olov Planthaber, Linköping University
In the first installment of Chipmetrics Profiles, we sit down with one of Sweden’s foremost ALD experts and discuss his experiences from using the PillarHall test chip.
In the ever-evolving landscape of semiconductor research, staying ahead requires innovative tools and groundbreaking approaches. Professor Henrik Pedersen of Sweden’s Linköping University, a world-renowned expert with two decades of experience in Chemical Vapor Deposition (CVD) and Atomic Layer Deposition (ALD), is breaking new ground in how we approach process control and material deposition on the atomic scale. His pioneering work with the Chipmetrics PillarHall test chip is setting new benchmarks for precision and efficiency in advanced semiconductor research and development.
A Lifelong Journey in CVD and ALD
Professor Pedersen has spent nearly 20 years exploring CVD and ALD processes, working with a diverse range of materials, from semiconductors and hard coatings to neutron detectors. “Our focus lies in the chemical reactions at the interface of gas and solid phases,” he explains. “By controlling surface chemistry, we can modify materials at the atomic level.” This meticulous attention to detail has enabled his team to achieve unparalleled control over material deposition – a critical factor for the next generation of devices.
The Role of Chipmetrics PillarHall in Process Control
Among the many tools in Professor Pedersen’s arsenal, the Chipmetrics PillarHall test chip stands out. Designed for process control and R&D in advanced semiconductors, this innovative chip provides researchers with a simple yet powerful way to measure and analyze deposition uniformity and step coverage deep inside complex structures. “PillarHall allows us to not only measure how far materials penetrate into a channel or trench, but also assess the quality of the material inside the trench,” Pedersen notes. “This was impossible to achieve with traditional methods.”
A Breakthrough with Heavy Gases
Perhaps the most exciting of Professor Pedersen’ recent discoveries involve the use of inert heavy gases to enhance material deposition in confined spaces. The inspiration came from a doctoral student’s observation: lowering the temperature to suppress gas-phase reactions improved deposition control but resulted in lower material density. This led to a revolutionary idea: introducing a heavy gas, such as xenon, to “push” source molecules deeper into microcavities without compromising temperature.
“We designed a series of experiments, and the results were astonishing,” Pedersen recounts. “Using xenon, we achieved significantly better step coverage at higher temperatures while maintaining uniform material quality. The heavy gas improved gas-phase collisions, spreading the reactants more uniformly and increasing deposition efficiency.”
Proving the Concept with PillarHall
The Chipmetrics PillarHall test chip played a pivotal role in validating these findings. “What makes PillarHall unique is its ability to open up and provide a clear view inside its channels,” Pedersen explains. “We conducted XPS analyses both inside and outside the channels and confirmed that the material properties remained consistent. This level of insight is unparalleled.” The results were so compelling that the research was published in Nature Communications after rigorous peer review.
Superconformal ALD: A New Frontier
Building on this breakthrough, Pedersen and his team explored how heavy gases could impact ALD. While conventional ALD excels in uniform material filling in deep trenches, the addition of a heavy inert gas led to a phenomenon called superconformal deposition. “We found that the gas facilitated faster growth at the bottom of the structure, filling it in a V-shaped manner,” the professor explains. “This approach, previously limited to CVD, is now achievable with ALD thanks to our method.”
The Road Ahead
As Professor Pedersen looks to the future, he envisions expanding this research into detailed atomic-level modeling and exploring its applications across a wider range of materials and structures. “Understanding the precise mechanisms at play will be key,” he says. “We’re already seeing how heavy gases and temperatures can revolutionize both CVD and ALD, but there’s so much more to uncover.”
Why PillarHall Matters
The Chipmetrics PillarHall test chip is more than just a tool; it’s a gateway to faster, more accurate data collection and analysis. It simplifies the process of evaluating material deposition inside confined spaces, enabling researchers to push the boundaries of what’s possible in semiconductor technology. “Before PillarHall, we couldn’t measure these effects as effectively,” Professor Pedersen emphasizes. “Now, we can unlock new levels of precision and innovation.”
Pedersen’s groundbreaking work highlights the transformative potential of combining expertise, creativity, and cutting-edge tools like Chipmetrics PillarHall. As the semiconductor industry continues to evolve, his contributions are paving the way for a future defined by unprecedented control and efficiency at the atomic scale.