Outgassing characterization of elastomeric seals used in semiconductor wafer processing

High or ultra-high vacuum (UHV) processes for integrated circuit manufacturing require close control of vacuum levels and uniform gas composition in the chamber in order to insure optimum process efficiency, product uniformity and product consistency. Outgassing from elastomeric seals can affect both vacuum level and consistency. A test methodology has been developed using a residual gas analyzer to measure the outgassing properties of elastomers. This paper compares the outgassing characteristics of three different types of elastomeric seals (perfluo-roelastomers, fluoroelastomers and silicones) typically used in semiconductor wafer processing using this test method. Data on outgassing rate as a function of time and temperature are presented. While perfluoroelastomers as a material class exhibit the lowest outgassing rate at elevated temperatures, there are some performance variations depending on formulation and compounding.