Silica conversion of polysilazanes by low-temperature plasma jet generated from Ar and water-vapor mixed gas

What is it about?

We have succeeded in forming SiO₂ thin films with a quality comparable to thermal oxide films formed at around 1000℃ using a low-temperature process at 52℃. This technology has the potential to contribute to the creation of new electronics fields, such as flexible electronics, and to promote the fusion of technologies across fields. Silicon dioxide (SiO₂) thin films can be formed on various substrates under non-vacuum, atmospheric pressure conditions using a precursor solution of perhydropolysilazane (PHPS). PHPS (SiH₂NH), which forms inorganic films, reacts with H₂O in the air to form a SiO₂ film through a hydrolysis reaction when heated at 450°C for more than one hour. If it becomes possible to convert to silica at a low temperature of around 50°C, which is the temperature that plastic film can withstand, it is expected to have a wide range of applications in next-generation flexible electronics and the creation of new electronics fields. We have succeeded in developing a technology to convert PHPS to silica at 52°C using our own approach to this issue.

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Photo by Onur Binay on Unsplash

Photo by Onur Binay on Unsplash

Why is it important?

If it becomes possible to form high-quality thermally oxidized SiO₂ films, which are used as gate insulating films in semiconductor devices, at low temperatures of around 50°C, which plastic films can withstand, and at high speeds, then revolutionary progress can be expected in many of the cutting-edge fields listed below. ‣ Application as gate insulating films in high-performance flexible TFTs (thin-film transistors) ‣ Application as insulating layers in flexible ICs and LSIs ‣ Application as foundational layers for transparent electronics ‣ Application as gas barrier layers Additionally, because plastic films are lightweight and cost-effective to produce, combining them with SiO₂ films could lead to the development of new eco-friendly electronic products, thereby contributing to sustainable technology. We successfully converted PHPS into an SiO₂ film comparable in quality to thermal oxide films at the low temperature of 52°C and elucidated the silica conversion mechanism using real-time FT-IR measurements. Understanding this mechanism is expected to lead to further technological innovations that enable even lower-temperature and faster silica conversion. Additionally, since SiO₂ films can be created at atmospheric pressure without a vacuum system, this technology can simplify production, reduce costs, and enhance scalability.

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