Repair of plasma-damaged p-SiOCH dielectric films in supercritical CO2

The silylation of plasma-damaged p-SiOCH low-k dielectric films was investigated with trimethychlorosilane (TMCS), hexamethyldisilazane (HMDS) and dimethyldichlorosilane (DMDCS) dissolved in supercritical CO2 (scCO(2)) and the effect of thermal pre-treatment on the repair performance was also studied. The surface hydrophobicity was rapidly recovered by silylation and the order of recovery efficiency was HMDS (85.4 degrees) > DMDCS (83.4 degrees) > TMCS (75.0 degrees). The FTIR analyses revealed that the restoration to the original state was not achieved over various reaction conditions (up to 31 MPa, 85 degrees C, and 3 h reaction time). After pre-treatment in a vacuum cell at 250 degrees C, the Si-O-Si peak intensity increased slightly, and the surface hydrophobicity was partially recovered to 54.4 degrees due to the removal of physically adsorbed H2O molecules as well as some extent of dehydration of neighboring surface silanol groups. The hydrophobicity increased to 84.4 degrees after subsequent treatment with HMDS in scCO(2). From DSIMS, the carbon concentration did not increase in bulk region after silylation of thermally pre-treated low-k films. (C) 2009 Elsevier B.V. All rights reserved.