The project established the trajectories of ENMs used in semiconductor fabrication and identified the operations of potential concern by a survey among the industrial safety professionals. The majority of the identified scenarios were related to chemical mechanical planarization and maintenance of deposition tools, which are processes particular to the semiconductor industry. However, no free ENM are present in the finished products. The potentials of exposure of personnel and release in the environment have been assessed for all trajectories. Encountered data gaps include (i) standard safety data sheets for chemical products do not contain information about the eventual presence of nanoforms and their characteristics and (ii) many generic nanotoxicity databases developed to date are not available for public use or the available data cover only a few materials, which are not used in the semiconductor device manufacturing. These gaps constitute a substantial impediment for assessing risks.
A large list of materials explored in semiconductor R&D pipeline has been also identified. By performing a thorough literature review, the consortium has identified some guiding principles in technological development for future technology nodes. ENMs are directly handled during the phase of lab-scale research where structures are produced in a bottom-up manner. This can pose occupational but not consumer or environmental risks. As the technology matures, the yield requirements lead to automation of wafer placement and thus direct handling of ENM is avoided. At this stage, free ENM may be present during some processing stages, but the consumer is not exposed during the intended use of the finished product. Finally, mature technologies for ultra-large-scale integration because of performance and yield requirements, lead to the deployment of nanopatterning approaches, compatible with the present planar technologies. That is, nanostructures are patterned in a top-down manner, which avoids direct exposure to the ENM and thus minimizes both occupational and consumer exposure. Therefore, top-down fabrication of nano-functionalized materials and devices is unlikely to add unanticipated hazards only because of the use of nanomaterials.
In a different task, tools for monitoring of occupational exposure, which are compatible with semiconductor clean rooms have been identified. Available guidelines and standards for exposure measurement have been compared and gaps in knowledge identified. It was established that monitoring of airborne nanoparticles is facilitated by the low emission backgrounds in the clean rooms and is attainable by some of the available instruments. On the other hand, measurements in clean rooms difficult to compare across sites. Therefore, the adoption of a harmonized measurement protocol is recommended in order to enable future standardization efforts. The consortium also recommends a detailed investigation of the composition of ENMs released in wastewater flows.
