Qualitative and quantitative characterization of outgassing from SU-8

SU-8 is often used as a structural material in Microsystems. In this work, the outgassing characteristics from such cross-linked SU-8 layers are studied using mass spectrometry and gas-chromatography techniques. With these methods the composition of the released matter can be identified, also the outgassing rate can be quantitatively characterized. A qualitative estimate of outgassing from SU-8 is given for cross-linked layers. The effect of hard-bakes is studied in situ by measuring at typical hard-bake temperatures. These tests indicate that a hard-bake is needed to provide good performance in UHV environments. Using gas-chromatography the outgassing rate from SU-8 is determined. The total outgassing rate is inversely proportional with time which further illustrates the effect of a hard-bake step.