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NANOmaterials: STRategies for Safety Assessments in advanced Integrated Circuits Manufacturing

Periodic Reporting for period 2 - NanoStreeM (NANOmaterials: STRategies for Safety Assessments in advanced Integrated Circuits Manufacturing)

Reporting period: 2017-07-01 to 2018-12-31

Nanoelectronics is a key enabler of global economic growth and development. A growing variety of engineered nanomaterials (ENM) is used in the development of integrated circuits, as companies seek to further improve devices’ performance to meet market demand. In some manufacturing processes, ENMs enable superior yields and performance of the final devices. Understanding the properties of such advanced materials and nanoforms and how they interact with living systems and the environment, often comes years after the materials have been introduced in manufacturing. Such an inherent uncertainty brings about multiple challenges in the governance of the occupational and environmental risks. This is a common situation for many technology-intensive sectors, and it requires a systematic risk reduction approach. This understanding was the driving force behind the NanoStreeM project. The objectives of the project were to
(i) build inventories of materials and research directions, relevant for nanomaterial use and exposure in nano-electronics manufacturing;
(ii) identify gaps in knowledge and methodologies to assess the risk of engineered or accidentally produced nanomaterials and
(iii) to inform stakeholders in order to support decision making and governance of the risks related to the use of nanomaterials and nanoforms in the semiconductor fabrication process.
The NanoStreeM consortium combines unique expertise throughout the research and development chain: from the academic labs via technology development through semiconductor application side. The companies represented in the consortium have some of the largest fabrication facilities in Europe and are globally representative. The consortium included leading centra of semiconductor research and academic institutions.
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.
NanoStreeM partners designed a tiered risk-assessment approach applying the principle of “safe-by-design”. The approach allows for the use of different, even sector-specific tools, in combination with emission field studies. The NanoStreeM approach includes the following tiers:
• Tier 0: Use of risk banding approaches to categorize risk: the ISO Standard ISO/TS 12901-2:2014 or StoffenManager Nano.
• Tier 1: Use of (semi) quantitative tools to give exposure estimated: NanoSafer, Consexpo, and ART
• Tier 2: Use of detailed emission measurement data to check the conclusions of Tier 1.
Finally, definite needs for competences development were established in terms of informing about the physicochemical properties of nanomaterials, a dedicated nanotoxicology knowledge base, and about the limitations of the traditional occupational chemical risk assessment. To meet these needs, the project composed three nanosafety training packages, as one of its major outcomes:
• An induction training package for technical personnel - first-time users nanomaterials with no prior experience.
• A training package for safety professionals to aid in their formative education concerning the properties of nanomaterials and available risk assessment methodologies.
• “Train the trainer” guideline for deployment of the training.
Developed training packages will be used by the semiconductor industry and the partnering institutions after the end of the project.
Project results were disseminated on a number of technical and policy-making fora. Notably, NanoStreeM organized three dedicated workshops. The workshop "Nanomaterial Risk Assessments and communication of their findings” presented the training strategy towards the internal stakeholder communities: researchers, technicians, trade unions and management. The workshop “Governance of emerging nano-risk in semiconductor industry” was co-organized with the caLIBRAte project. It was geared towards the external stakeholders from the public authorities and the European institutions. The emphasis was on the generic approaches in the risk assessment and governance, which can be employed also by other industries having rapid technological turnover and innovation. The workshop “Novel materials and nano-risk in semiconductor industry” presented the findings of work package 1. Public findings are also disseminated using YouTube and LinkedIn channels.
Risk assessment and control methodology
Increasing process complexity