By Will Soutter
An innovative technique for measuring the retention of particles less than 10 nm in dimensions was presented by Entegris at the 11th International Symposium on Ultra Clean Processing of Semiconductor Surfaces (UCPSS) held from September 16 to 19, 2012 at Ghent in Belgium.
Entegris supplies a vast range of products for protection, purification and transportation of materials used in the semiconductor industry. The method devised by Entegris employs fluorescent quantum dots of Cadmium Selenide (CdSe) to accurately measure the retention capability of advanced filters used in semiconductor device manufacturing.
The manufacturing process for next generation semiconductor-based devices incorporates new filter membranes with capability to eliminate particle contaminants that measure less than 10 nm in size. The filter membrane performance is chiefly characterized by the pore size which is typically represented as average pore diameter. Since particles of such small dimensions cannot be measured owing to the lack of precise metrology tools, it has been difficult to measure the pore size of such fine filters.
The new technique devised by engineers at Entegris can be used to measure retention capability of ultra-high molecular weight polyethylene membranes measuring 3 nm, 5 nm and 10 nm in pore diameter. Quantum dots are minuscule nanocrystals which emanate light of various fluorescent colors corresponding to the size of quantum dot.
A technical paper presentation on the use of quantum dot technology in applications pertaining to photolithography filtration is scheduled to be delivered by Entegris at the SPIE Advanced Lithography conference to be held at San Jose in California in February 2013.