When processed correctly, PTFE easily meets increasing fluid handling requirements in the semiconductor industry.

The many advancements that have been made in electronics over the recent decades have driven the price of electronics down and reduced device size while increasing processing speeds. These advancements can primarily be attributed to the semiconductor manufacturers’ ability to reduce the size of features that are etched on silicon wafers. As these feature sizes have been reduced, processing fluid purity requirements and reactivity have increased. This combination of cleanliness requirements and chemical reactivity present many challenges to fluid handling component materials. Polytetrafluoroethylene (PTFE) is one material that, when processed correctly, easily meets increasing fluid handling requirements in the semiconductor industry.

High purity chemicals and ultra pure water are two common fluids that are used to etch features on silicon wafers. As feature line widths decrease, semiconductors become more sensitive to any impurities that are contained in these fluids. To maintain purity, fluid handling materials must not react with these fluids or release contaminates. Furthermore, they must be able to be cleaned to accommodate new chemicals as technologies advance.

To achieve these requirements, wetted surfaces must be made of materials that are non-reactive with a wide variety of chemicals, do not contain impurities that can be released into the fluid stream, and will not absorb contaminates. Introduction of a pollutant into the wafer manufacturing process could cause the loss of millions of dollars worth of product, not to mention the downtime to identify the source of the contaminant and re-commission the process.

PTFE was discovered by accident in 1938 when DuPont chemist, Roy Plunkett, found a white powdery substance inside a cylinder that had been previously filled with tetrafluoroethylene (TFE) gas. Testing revealed that the material was PTFE. The key advantages of this newly discovered material were its low coefficient of friction, compatibility with other chemicals, and high melting point. PTFE was first used in military applications, but over the years many other uses have been found for it. PTFE is commonly used in ultra high purity fluid storage, transport, monitoring, and control. Skived PTFE material can be used to line tanks and transport vessels. Machined PTFE is used to make components such as manifolds, pumps, valves, seals, wafer carriers, heat exchangers, and fittings.

PTFE is an ideal material for semiconductor fluid handling. It is inherently inert because it is composed of only carbon and fluorine atoms. The carbon fluorine bond is one of the strongest known. The strength of these bonds prevents PTFE from being degraded by chemicals or absorbing them. These bonds also permit PTFE to withstand temperatures ranging from -270ºC to 260ºC.