In the semiconductor industry, large quantities of ultra pure water are used for production and rinsing processes. At the same time an equvalent , a lot of waste water is produced, which is contaminated in many different ways. These waste water streams are separated according to contamination and collected separately. Low-loaded partial streams, for example from the last rinsing steps of the wafers, can be recovered. This is especially true if they have very low TOC concentrations. The more heavily polluted waste water is treated in a tailored manner. In both cases, the treatment plant is individually adapted to the respective waste water composition.
HF waste water treatment for semiconductor and solar cell production
Large quantities of hydrofluoric acid (HF) are required for the etching processes during production and are later found in the waste water. Before waste water can be discharged or reused, hydrofluoric acid and its salts must be removed. The waste water is treated by precipitation and flocculation. The fluoride contained is precipitated as calcium fluoride by the addition of lime milk or calcium chloride. This process step produces calcium fluoride sludge, which is dewatered and disposed of.
CMP waste water treatment for semiconductor production
During planarization of the wafer surfaces, waste water is generated that contains grinding aids and mostly copper ions from the removed copper coatings. The used slurries and auxiliaries lead to high concentrations of solid particles in the waste water. In order to be able to discharge the waste water later, the copper ions contained in it are removed by means of precipitation and flocculation. The metal-containing sludge which is produced must then be dewatered and disposed of. The downstream selective ion exchangers remove the copper up to the prescribed discharge limits.
Neutralisation for semiconductor and solar cell production
As a rule, the waste water from the aforementioned partial flow treatments still exceeds the pH range permissible for discharge. Therefore, this waste water, together with other slightly contaminated rinsing waters, undergoes a multi-stage neutralisation process in order to meet the legal requirements for discharge be discharged into the sewer system. Depending on the throughput and the site-specific wastewater composition, we optimise the concept and design of your plants to your individual requirements and wishes.
