Chemistry | CMP: Slurry Measurements

Online monitoring of slurry properties in CMP processes provides real-time data to control the slurrys health and to detect changes in abrasive concentration. A stable slurry density within the specification limits guarantees the production of a high quality wafer surface.

Chemical mechanical planarization (CMP) is a critical production step during microcircuit manufacturing. The smaller the electronic components, the more sophisticated the CMP process. The customer goal is to have flat, smooth, polished wafers.

The polishing procedure is performed in clean room where the air contains less than one dust particle per cubic meter. Slurry containing mainly pure water, a chemical reagent and different polishing particles are used between the polishing pad and the wafer. A slurry's "health" depends on its stability and contamination level. Foreign particles, solved carbon dioxide and ionic contaminations can disturb the polishing process as well as slurry particle aggregates and agglomerates. A dynamic measurement of the slurry properties coupled with defined control limits can be used to determine a slurry health.

Especially multipart slurries used in the semiconductor industry lead to a quick separation. Even if the slurry particles are small, the particles will move down because of the higher density. Quasi homogeneous slurries are commonly delivered in concentrates and diluted with water on site.

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