When circuits are formed on wafers during semiconductor manufacturing, circuit patterns are transferred by applying the same mechanisms used by cameras when exposing and developing film. All residual cleaning solvents are collected at our manufacturing sites in Japan, distilled and refined by an outside contractor, and then reused.
At Kioxia Corporation’s Yokkaichi Plant, hydrofluoric acid used in wafer cleaning and circuit shape processing is also collected and processed at an artificial fluorite production facility. By recovering the calcium fluoride (artificial fluorite), the amount of sludge containing hydrofluoric acid is reduced by approximately 30%. The recovered calcium fluoride is used as a fluorine-based material by fluorine-based product manufacturers as an alternative to fluorite, an imported natural resource, helping to curb imports of this scarce mineral.
In addition, polyimide, used as a film-forming material for wafers, used to be disposed of after use, but as a result of a reevaluation of its potential value following a change in composition, it can now be reused. After recovery, it is distilled and refined and used mainly as a raw material for paints.