Over the last decade, the company’s researchers have published various papers on the growth of silicon dioxide films directly on a silicon substrate through UV irradiation in a pure or highly concentrated ozone environment, but surface temperature reached several hundred degrees celsius.
According to a Nikkei’s news report, for the first time, the company was able to form such oxide films in a controllable manner at room temperature by chemically combining ozone (O3) and ethylene to produce hydroxyl radicals, which then reacted with tetraethylorthosilicate (SiC8H20O4, TEOS gas) to decompose into silicon dioxide, carbon dioxide, water and oxygen. Once the resulting water and gas by-products are removed as impurities, the SiO2 precipitates onto the substrate, forming a high-purity SiO2 film. With the new technology, a film can be formed on a plastic film at a room temperature of 30°C, a world’s first according to the company, noting that today’s low-temperature alternatives rely on plasmas, raising the temperature to between 100 and 150°C.
With the new process, the thickness of film is tuneable from 5nm to 780nm so as the film’s composition, by changing the gas mix to obtain other metal oxide films such as aluminium oxide films and high dielectric films. The company claims that multi-layered films could be formed by changing the gas mix in the reaction chamber, while cutting processing costs through better overall energy efficiency.
Since the oxide films exhibit excellent scratch resistance, bendability and barrier properties, they could be used in the manufacture of flexible displays.
Meidensha – www.meidensha.com