Almost every production stage in the semiconductor industry is characterized by the demand for the highest possible cleanliness and particle freedom of the working environment and all the media used in it. As semiconductor products become steadily smaller and more efficient, the fabrication of wafer surfaces is carried out in dimensions of 1 µm and below. Any disturbing particle can make a chip useless. Therefore most of production processes are carried out in cleanrooms, using ultrapure water. Here, our filter elements are used for de-dusting in supply air and exhaust air ducts, mostly as pre-filters prior to HEPA filtration. Our products are also used as pre-filters In the production of the process water prior to further treatment steps like ion exchange or reverse osmosis. In addition, there are other important applications in the filtration of liquid and gaseous media.
Filter units for printers
Wax ink filtration is an important example of filter application in chip production. The separation of conductive and insulated regions on the surface of chips and the embedding of electrical resistances at clearly defined places is is done by ink jet printers. Here again, filtration is needed to remove any disturbing particles (gel particles, agglomerates) so as to prevent blockage of the ink jets.
Filtration of operating media
Effective utilization of filter elements is extremely important in the filtration of operating media. The ability to maintain operating times for as long as possible without process interruptions minimizes the whole costs of a production plant. The high level of cleanability and durability of our filter elements are also decisive for the efficiency of subsequent process steps.
Ultrapure water is an important operating medium. It is produced on-site by means of several different treatment stages Here, particle filtration is decisive for separating colloidal silicic acid and other ultra-fine particles in order to protect subsequent systems like ion exchangers or reverse osmosis systems. High-grade system components used in water treatment must be protected against abrasive particles. Such components include high-grade magnetic valves, electrically or pneumatically driven valves, and sensitive sensors for pressure or flow measurement.
In the semiconductor industry, important raw materials are supplied as gases, e.g. for coating from the gaseous phase as in plasma processes or with chemical vapour deposition (CVD). Large amounts of carrier gases (e.g. nitrogen) are needed for this. The safe separation of particles and droplets from all process gases is indispensable.
Furthermore, many processes produce hot and chemically aggressive gases, which sometimes have to be treated directly at the point of origin. Here, our particle filters provide important services for direct gas filtration, as well as for the treatment and recycling of waste waters emerging from gas scrubbing systems, in which gaseous pollutants are transferred to solid precipitants.
Recovery of valuable substances
Our cleanable, stainless steel filter systems can be used to recover valuable materials from exhaust gas and waste water flows. These materials can be transferred to further treatment stages or returned directly back into the production process. With most nonwoven filters, particles enter the fibre matrix and cannot be removed. When a certain pressure loss is reached, the filters have to be replaced and disposed of as waste.
Process water treatment and subsequent reuse in the process provides an essential contribution to sustainable and resource-saving production processes. One example is the treatment of abrasive pastes (CMP-slurries), which are used for polishing raw silicon wafers. The filter retains all suspended solids and the water can be reused in the polishing process.