fluoropolymers

The semiconductor industry must do far more to educate the electronics supply chain on the subtle differences among various fluoropolymers, 30 SEMI member companies learned in an October 13 webinar organized by SEMI to help maintain a unified voice on the critical importance of per- and polyfluoroalkyl substances (PFAS) in semiconductor manufacturing. At the same time, producers and customers of the substances used in chipmaking should work more closely together to steer clear of adopting policies that could limit the availability of safe fluoropolymers and the semiconductor industry’s ability to use them in the future.The insights were offered by representatives from the Performance Fluoropolymer Partnership – a group within the Washington, D.C.-based American Chemistry Council – on per- and poly-fluorinated substances including fluoropolymers. The Council is an industry trade association representing American chemical companies. Following are other key takeaways from the webinar. Fluorinated polymers and non-polymers are commonly found in components used in semiconductor manufacturing such as fittings, valves, tubes, O-rings, wafer carriers, filtration media, high purity air filters, greases and lubricants. The substances are ideal for use in corrosive chemicals, high temperatures and other harsh environments and are found in a variety of electro-technical components such as potentiometers, wiring, printed circuit boards and Lithium-ion batteries. Fluoropolymers are a diverse family of plastics also widespread in modern life, with applications ranging from food packaging and non-stick coatings on kitchen pans to rechargeable batteries for electric vehicles. The term PFAS (per- and poly-fluoroalkyl substances) covers more than 4,700 chemicals with diverse physical, chemical, environmental and biological properties and impacts. There are also significant differences among their chemical compositions. A careful appraisal of their risks and impacts should take into account any potentially hazardous properties, toxicity levels, their prevalence in the industry, and whether substitutes are readily available. Growing pressure from regulators worldwide threatens future access to fluorinated chemicals, increasing the importance of raising awareness on how to distinguish groups of chemicals and encouraging a measured approach towards eliminating only chemicals carrying the greatest risk. Fluoropolymer producers and opponents of the chemicals must look past their divergent interests to work together to voice common concerns to regulators. Various SEMI working groups respond to public consultations when opportunities to present the semiconductor industry’s position arise. Individual group members communicate both among each other regarding new regulatory developments and also with external constituents through SEMI about the importance of chemicals to chip manufacturing. As with other sectors, the semiconductor industry continuously seeks to “green” its manufacturing processes. SEMI believes the commitment of the supply chain to these efforts is crucial to protecting the industry’s interests and driving innovation.Olivier Corvez is senior manager of Environment, Health, Safety and Sustainability at SEMI.

On behalf of its global membership, SEMI is actively addressing a variety of environment, health and safety (EHS) dossiers impacting the semiconductor manufacturing supply chain. Together with its dedicated working groups (WGs), SEMI educates regulators globally on semiconductor manufacturing technology and advocates a balanced policy framework supporting innovation, growth and sustainability.Perfluorooctanoic acid and related compounds and salts (collectively known as PFOA) have been on the radar of the SEMI PFOA WG and EHS Advocacy Program for several years. PFOA is reported to cause severe and irreversible adverse effects to the environment and human health. PFOA is very stable and will last for years in the environment, and so it is considered a Persistent Organic Pollutant (POP). As such, PFOA is in scope of the Stockholm Convention and meetings to consider revisions to the Convention take place regularly. During these consultative meetings, Parties to the Convention are invited to provide observations and propose amendments. SEMI participated in the ninth meeting of the Conference of Parties (COP) in Geneva in late April and early May to provide the position of the semiconductor manufacturing industry.Among the many substances used to manufacture equipment components, fluoropolymers and fluoroelastomers (together known as fluoromaterials) have been produced sometimes with PFOA as a processing aid. To reduce hazardous effects to the environment and human health and to meet regulatory obligations, many (but not all) fluoromaterial manufacturers worldwide have been eliminating PFOA from their processes. Over the past several years, the WG has been studying equipment components – as well as related supply chains – that might contain fluoromaterials made with PFOA. The WG has learned that if PFOA is present in fluoromaterials, it is only as an unintentional contaminant or impurity. The WG has also confirmed that PFOA serves no intended purpose or performance function in the fluoromaterial-containing components that might be present in semiconductor manufacturing equipment. Although more testing is needed, the WG also believes PFOA that might be present in fluoromaterials does not move freely out of the material into the surrounding environment. In this light, the WG reviewed a draft of exemption recommendations from the Persistent Organic Pollutants Review Committee (POPRC) to the full Stockholm Convention. The exemptions in the draft recommendations addressed new and legacy equipment, fabrication plant-related infrastructure and related refurbishment parts for the manufacture of semiconductors and related electronic devices, and it imposed a commitment to remove any ‘PFOA residue’ from equipment components in five years (10 years for legacy equipment and refurbishment parts). Additionally, there was also an exemption in the draft for PFOA related to photo-lithography and etch processes, which the WG fully supported to maintain, as the presence of PFOA in process chemicals is fairly well understood, but viable substitutes have not yet been found for some applications.The outcome of the WG review was a concern because the equipment-focused exemptions introduced the concept of a ‘PFOA residue,’ and the Stockholm Convention already contains an exemption for ‘Unintentional Trace Contaminants’ (UTCs). The WG concluded that the existing UTC exemption was already sufficient. Additionally, although the WG does have spot information that PFAO can be present in fluoromaterial components, there is no comprehensive data about PFOA presence throughout the deep and complex equipment component supply chain, particularly regarding older parts in storage.Additionally, the WG has seen that very low levels of PFOA can be unintentionally created by some fluoromaterial post-processing steps such as processes intended to control PTFE polymer chain length in fluoro-lubricants that unintentionally create small quantities PFOA (note that PFOA is roughly a very short PTFE chain with a ‘carboxyl’ ending). Also, the WG has learned that PFOA can, in some cases, be accidentally created from fluoropolymers, adding to doubts as to whether ‘PFOA free’ can be determined or achieved. Therefore, the commitment contained in the draft exemption to have all ‘PFOA residues’ removed in five or 10 years was not based on a well-defined action timeline.Therefore, the WG in its discussions with governments around the world, prior to and during the Stockholm Convention COP meetings, requested the removal of specific exemptions related to equipment used in semiconductor manufacturing. The WG also requested that the specific exemption related to photolithography or etch processes be maintained. SEMI appreciates that its recommendations were accepted by the COP. This will help avoid country-specific regulations based on the Convention that are not fit-for-purpose. SEMI and its WG will continue to study PFOA and its elimination from the semiconductor manufacturing supply chain, and educate regulators globally on semiconductor manufacturing technology, underpinning sustainability, innovation and growth in a balanced manner.

IntroductionStarting July 4, 2022, PFOA (Perfluorooctanoic acid) levels in semiconductor manufacturing and related equipment (SMRE), including replacement parts, entering the European Union (EU) will be restricted to 25 ppb per component (or any part thereof). Semiconductor equipment components (and the parts thereof) of particular concern include fluid tubing and fittings, pipe/seal tape, wire and cable insulation, filters, valves, tanks, panels, reaction vessels and o-rings; if they are made from fluoropolymers or fluoroelastomers.When PFOA is used as an aid to the manufacture fluoropolymers such as PTFE, PFA, PVDF or fluoroelastomers such as FKM and FFKM (collectively referred to as fluoromaterials), an unintended PFOA residue can be trapped within the fluoromaterial. Buyers of components used in SMRE are usually unaware of the processing method used for any fluoromaterials they may contain, and, as a consequence, the potential for PFOA residue. This lack of information about potential PFOA residues could result in regulatory enforcement actions and restricted market access, particularly in the EU.The impact of restrictions on fluoromaterials used in SMRE has been introduced in previous SEMI articles ‘Fluorinated Compound Restrictions May Trigger Costly Equipment Changes’ and ‘Fluorinated Substance Restrictions Triggers Costly Equipment Changes.’PFOA and its related compounds, such as the ammonium salt APFO (collectively called PFOA in this article), are recognized internationally as hazardous chemicals and are now targeted for regulatory restriction in the U.S., Taiwan, Canada and the EU. The UN Stockholm Convention on Persistent Organic Pollutants (POPs) is also considering listing PFOA, which could lead to additional international restrictions.The SEMI EHS Division PFOA Compliance Working Group has been working to understand: The likelihood of PFOA residue entering the supply chain of new components The residual level of PFOA in fluoromaterials produced prior to the phase out of PFOA by some manufacturers The impact of PFOA residue on the secondary equipment market This SEMI resource page, ‘Elimination of PFOA from the Equipment Supply Chain,’ and the supporting FAQ contain the Working Group’s key findings and conclusions.PFOA in the Fluoromaterial Supply ChainSignatories to the U.S. EPA Stewardship Program, which include FluoroCouncil members, eliminated PFOA from their manufacturing processes by 2013. However, other fluoromaterial manufactures – particularly in China, Russia and India – might still use PFOA and pose a significant risk to the worldwide supply chain.China, the world’s largest fluoromaterial producer, accounts for 53 percent of global production of PTFE and 38 percent of worldwide production of PVDF, FEP and FKM. An estimated 75 percent to 85 percent of fluoromaterials are manufactured using PFOA in China. Fully 25 percent of these fluoromaterials are exported, primarily to the U.S, Japan, EU and India. What’s more, finished goods made from or containing fluoromaterials that might be used as components in SMRE are exported from China.Documentation that traces fluoromaterials through the supply chain back to the original fluoromaterial manufacturer is key to meeting the PFOA regulatory requirements. This traceability can be straightforward in cases when an SMRE manufacturer directly specifies the use of a fluoromaterial in a custom-fabricated fluoromaterial component. However, for off-the-shelf components (e.g., cable ties, wiring insulation, tubing) or the components assembled from these components (e.g., controllers), the complexity and dynamics of the supply chain makes traceability back to the original fluoromaterial producer almost impossible.Residual PFOA Levels If, or how much, PFOA/APFO residue is contained in a fluoromaterial depends on the manufacturing process. Details of the manufacturing processes are proprietary and vary widely. Post manufacturing thermal treatments, such as sintering, extrusion, and molding, can result in the rapid thermal decomposition of APFO above 250C, but PFOA is significantly more stable. The temperature and time of thermal treatments is also proprietary and varies depending on the type of fluoromaterial and what is being made.This variability makes it impossible to estimate the likely level of trapped PFOA or APFO in a finished component or a part thereof. It is unwise to use data on the level of residue made known for one case to extrapolate the level of residue across the fluoromaterial industry. However, an industry-wide range on the order of 1ppm-10ppm (nearly 1000 times the EU limit) is suspected. Testing for the presence of PFOA/APFO at 25ppb in components is also problematic as there is no standard test method, and results among the custom methods developed in each test lab may vary.Given this uncertainty in test methods, a system of supplier declarations warrants consideration.Impact on Secondary (Used) EquipmentThe EU REACH restrictions apply to SMRE and replacement parts placed on the market at any time (not just initial placement – known as “first placing on the market”). For fluoromaterial components manufactured prior to 2013, there is a higher likelihood of residual PFOA/APFO levels exceeding the 25ppb limit of EU REACH. In principle all the SMRE components containing fluoromaterials should be investigated, and those containing PFOA above 25ppb must be replaced before the SMRE can be legally placed again on the EU market. Companies (e.g., semiconductor manufacturers) in the EU who wish to sell used equipment within the EU will be required to demonstrate the used equipment is in compliance. Selling older used equipment would likely be unprofitable after necessary investigations and component replacements are completed.Next StepsWhile the EU semiconductor manufacturing industry heavily depends on the secondary (used) equipment market, EU regulators may be unaware of the PFOA restriction’s damaging impact to this market. The EHS Division PFOA Working Group, in conjunction with SEMI Europe, is now considering how to bring this concern to the attention of regulators and to collaborate and lobby for effective changes including possible modifications to the EU Persistent Organic Pollutants (POPs) regulation.