The challenge was that TARCs need fluorinated materials like PFOS to achieve a very low refractive index, but these new materials need to behave like PFOS and be environmentally friendly. Following the US Environmental Protection Agency’s announced interest in seeking PFOS-free materials, we set out to develop a TARC platform that avoided the use of PFOS acids, so that the semiconductor industry could continue to use advanced TARC technology without concerns about their environmental impact.
By 2005, the EMD Performance Materials project team in Japan had identified a perfluoropolymer that avoided the use of both PFOS and PFOA (perfluro-octanoic acid – a close relative of PFOS that also has undesirable environmental effects) polymers. After a robust testing programme which evaluated a number of TARC formulations with the broad range of advanced photoresists used in manufacturing, and with an eye to the future materials which might come into practice for the next IC nodes, the AZ team completed an optimised formulation which would accomplish the performance as well as the environmental goals.
The key challenge now was how to take this new product into commercial production. For this we worked in close partnership with a key supplier in Japan, who was also an expert in fluoropolymer manufacturing. Our supplier capably scaled-up our new polymer design into a commercial process, achieving the critical batch-to-batch quality and consistency necessary for electronic-grade commercial products, and completing the exercise well within the timeframe needed to meet the regulatory requirements which were fast approaching the semiconductor industry.
As a result, AZ® Aquatar®-VIII Coating was launched, based upon the EMD Performance Materials-designed, key supplier-made polymer and over the next four years nearly all of our customers, as well as new customers, converted to the new material from the PFOS TARCs.
Today, the semiconductor industry continues to rely on TARC processes for the commercial manufacture of integrated circuits, using the innovation developed by our R&D teams and commercialised through our partnership in innovation with our qualified supply chain partner.