Utilizing Porous Low-k Dielectrics for Self-Monitoring of Vacuum Chamber Contamination

Contamination within vacuum chambers poses a persistent challenge, negatively impacting the reliability of materials used in integrated circuits. To mitigate this issue, a self-monitoring sensor system employing porous low-k dielectric films as witness samples was developed for in-situ contamination detection within vacuum environments. Porous films offer distinct advantages, primarily due to their high internal specific surface area, which facilitates enhanced adsorption of organic compounds. The efficacy of this system was investigated using porous low-k methyl-terminated organosilica glass (OSG) and ethylene-bridged periodic mesoporous organosilica (PMO) films, subjected to a range of simulated chamber conditions: vacuum exposure, N2 purging, UV irradiation, and H2 plasma treatment via capacitively coupled plasma (CCP). This approach provides a sensitive and real-time method for evaluating chamber cleanliness, critical for accurate processing and subsequent analysis. After exposure, the samples are analyzed by FTIR spectroscopy and ellipsometric porosimetry. Detection of hydrocarbon absorption bands by FTIR or changes in porosity measured by ellipsometric porosimetry indicates the presence of residual hydrocarbons within the chamber. Combining FTIR (chemical fingerprinting) with porosimetry (structural access) on witness samples enables the detection of contamination that alters dielectric properties and pore accessibility, providing a sensitive and real-time method for evaluating chamber cleanliness, critical for accurate processing and subsequent analysis.