After more than ten years of development, engineers have unveiled a new semiconductor etching method that could significantly speed up chip manufacturing while reducing its environmental impact.
The process, developed by Tokyo Electron Miyagi Ltd. and studied in collaboration with researchers at Nagoya University, can remove material from silicon wafers up to five times faster than conventional techniques.
The research explaining how this dramatic improvement works was published in the Chemical Engineering Journal.
Etching is a crucial step in making computer chips. During this process, tiny patterns are carved into a silicon wafer to create circuits and transistors.
Modern chips rely on extremely complex three-dimensional structures, such as gate-all-around transistors and 3D NAND memory, which are much deeper than they are wide.
As these structures become smaller and more intricate, it has become increasingly difficult to deliver etching chemicals deep into narrow spaces. This has slowed down manufacturing and reduced overall productivity.
The new approach tackles this problem by using hydrogen fluoride (HF) plasma at very low temperatures, around minus 60 degrees Celsius.
Unlike commonly used fluorocarbon gases, which are powerful greenhouse gases, hydrogen fluoride has a much lower global warming potential. This makes the process not only faster but also more environmentally friendly.
Earlier experiments had hinted that cooling silicon-based materials could dramatically speed up etching.
However, the reasons behind this effect were not well understood. To find out what was happening, the research team closely examined how HF plasma interacts with silicon dioxide, a material widely used in chip manufacturing.
They discovered that at ultra-low temperatures, both hydrogen fluoride and water molecules stick to the surface being etched. Surprisingly, the water does not slow the process down. Instead, it acts as a catalyst, making it much easier for chemical reactions to occur.
In fact, the presence of water lowers the energy barrier for etching to nearly zero, allowing the material to be removed extremely efficiently.
The team also found that when energetic ions from the plasma strike the surface, they help generate more water molecules. These water molecules attract even more hydrogen fluoride, creating a self-reinforcing cycle that rapidly accelerates the etching process. As a result, the etch rate increases exponentially with ion energy, far beyond what is seen in traditional methods.
Under optimized conditions, the researchers achieved an etching throughput for silicon dioxide films that was about 100 times higher than that of conventional room-temperature processes using low-energy ions. This means chip features can be carved much more quickly, which could translate into faster production and lower energy use in factories.
Equally important, replacing fluorocarbon gases with hydrogen fluoride removes a major source of carbon emissions from the etching step. According to the researchers, this could help chipmakers reduce the environmental footprint of advanced semiconductor manufacturing.
With successful tests carried out in equipment similar to real production tools, the team now aims to bring this technology into full-scale manufacturing lines, potentially reshaping how future computer chips are made.
