By dipping in a silanisation solution, a hydrophobic self-organized nanomolecular film (SOM) was successfully grown on the surface of dry-etched porous methyl silsesquioxane (DE-PMSQ). The reaction was spontaneous at room temperature. The moisture adsorption on the DE-PMSQ was avoided and the surface of the SOM/DE-PMSQ was rather smooth. Leakage current and dielectric constant measurements of DE-PMSQ and SOM/DE-PMSQ samples also showed consistent behavior. As a result, it is promising to use the low-k PMSQ as an inter-metal dielectric with hydrophobic SOM grown on DE-PMSQ. (C) 2003 The Electrochemical Society.