Low Stiction PFR FFKM and Related Test Method
ABSTRACT
Perfluoroelastomers (FFKMs) are key raw materials for producing seal elements for applications in semiconductor manufacturing. Beside the required resistance to harsh chemical environments, typical of dry- and wet-etch chambers, and a high thermal rating, usually 300°C and beyond, FFKM-based seals are also expected to show no stiction especially when used for dynamic seals, i.e. gaskets of moving parts. Stiction is a term used for the unwanted tack or residual adhesion that can be shown by sealing elements. Damage to the seal from stiction events can lead to seal failure which results in yield loss and increased downtime. For example, etching applications in particular are based on a very precise dosing of different chemicals, which are fed through valves that open and close following an engineered time-profile. Stiction can interfere with the accuracy of this dosing profile by delaying the opening of a valve when an adhesion force to the mating surface is present. Downtime and yield loss can also occur in static sealing applications, whereas a seal breaks by sticking to the groove when opening the equipment.
Therefore, it was of interest, first, to introduce a test method capable of measuring, in a reproducible and accurate manner, the stiction exhibited by different seal elements; and second, to develop FFKM compounds that minimize such residual stiction to metal.
In this presentation, we will describe how Syensqo labs have developed test equipment, designed to be installed on commonly available dynamometers, and created a dedicated test method which ensures accurate and reproducible stiction values. This test is run on standard o-rings (e.g. AS568A-214 o-rings) and does not require special handling of the samples or additional safety measures.
With the help of this equipment and method, we were able to study the structure-property relationships of our Tecnoflon® PFR FFKM that define the stiction force of seals made thereof. This was the needed scientific background for the optimization work of compounds based on our new NFS FFKMs, that show a residual stiction below reference values and represent therefore an optimal solution for the Semicon industry. Indeed, ""low stiction"" (LS) PFR FFKMs can be offered to market as ready-to-use polymers with the added value of a reduced stiction, thanks to an engineered additive developed in our Bollate labs and formulated into the polymer as supplied. These LS PFR FFKMs showed a reduction between 60% and 40% of their reference stiction value without the proprietary LS additive. We have also demonstrated that outgassing properties and plasma resistance are not significantly affected by the LS technology.
BIOGRAPHY
Emmanuel Anim-Danso is a CTD Engineer at Syensqo, specializing in advanced materials for the electronics and industrial sector. Since joining the company he has led and contributed to multidisciplinary projects focused on high-performance polymers and innovative material solutions. Emmanuel holds a Ph.D. in Polymer Science from the University of Akron and a B.S. in Chemistry from Rutgers. His expertise includes polymer compounding, advanced materials characterization, fluoropolymers, and the development of novel test methods to optimize performance and reliability in demanding applications.