In situ ellipsometry of porous low-dielectric constant films in supercritical carbon dioxide

This paper reports the results of in situ ellipsometric measurements on porous low-dielectric constant thin films being placed in a mixture of supercritical CO2 and an organic solvent, intending the detection of the pores. Different low-k films having a dielectric constant of 2.2–3.1 were examined at pressures of 10–14 MPa and temperatures of 40–100 °C. Large changes in ellipsometric parameters were observed upon the addition of the solvent, in any condition studied, when spin-on-dielectric films that have micropores were used. Measurement conditions for films with a smaller pore size were explored and the detection of supermicropores in plasma-enhanced chemical-vapor-deposited SiOCH was succeeded.