Thermal Vacuum Analysis and Identification of Contaminant Outgassing from Polymer Seals
ABSTRACT
Organic outgassing from polymeric materials, particularly elastomer seals and o-rings used in high-vacuum process equipment, remains a critical source of Airborne Molecular Contamination (AMC)1. These contaminants lead to detrimental device defects and reduced yields in advanced semiconductor manufacturing nodes2. While single quadrupole residual gas analyzers (RGA) are commonly utilized for real-time process monitoring and thermal desorption spectroscopy (TDS), they possess inherent limitations in mass resolution3333. Standard RGA tools cannot distinguish between key chemical fragments that share the same nominal mass, such as the fluorinated CF3+ (m/z 68.9952), the alkyl C5H9+ (m/z 69.0704), and the oxidized C4H5O+ (m/z 69.0340). This ambiguity hinders the development of effective contamination control strategies, as the origin and risk of these distinct species vary significantly.
This study presents a synergistic analytical approach that combines the real-time monitoring capabilities of Ultrahigh vacuum (UHV) RGA-TDS with the high-resolution quantitative mass separation of Solid Phase Microextraction-Gas Chromatography–Quadrupole-Time of Flight (SPME-GC-qTOF) mass spectrometry. By applying a linear heating profile to 120°C followed by an isothermal hold, elastomer materials were characterized in environments representative of actual processing conditions. While TDS analysis confirmed water (m/z 18) as the dominant outgassing species, it also highlighted the necessity for higher resolution to characterize trace species fluctuating near the detection limit.
The SPME-GC-qTOF analysis successfully resolved thirteen distinct chromatographic peaks, categorized as ""medium boilers"" based on a C6 to C28 alkane standard, where elution was greater than C10, but less than or equal to C20. The exact mass separation allowed for the precise identification of various fragments at the nominal m/z 69 position10. Significant findings revealed that Peak 1 was the primary contributor to specific problematic ions CF3+ and C5H9+, despite accounting for only 8% of the total integrated area. Conversely, Peak 8 contributed the majority of the total outgassing (18%) but showed much lower contributions to these specific critical fragments than anticipated. These results demonstrate that total outgassing levels can be a misleading metric for assessing specific contamination risks. By providing structural elucidation and exact mass data, this complementary technique offers semiconductor manufacturers the critical reliability physics data needed to qualify next-generation low-outgassing materials and implement focused contamination reduction strategies.
This research is ongoing, and we expect to have more results such as running the same samples and more structural elucidation. Please see attached supplementary info for the data so far.
BIOGRAPHY
Dr. Allen Chan is an R&D Scientist at Balazs NanoAnalysis. His current projects include development of new sampling methods and techniques for liquids, air, and solid outgassing for the Semiconductor Industry. Allen received his B.S. in Chemistry from the University of California, San Diego and his Ph.D. in Organic Chemistry from the University of California, Riverside.