Investigation of adhesion mechanism and pore-sealing layer between tantalum barrier layer and porous SiLK

Abstract

The structure of SiLK was determined by comparing the predicted properties with experimental values. Quantitative structure-property relationship (QSPR) was used to predict the properties of polymers from three kinds of possible repeating units, the structure with the predicted properties most close to experimental values was determined as the repeating unit in real SiLK. With this repeating unit, mechanism of Ta adhesion on SiLK was investigated. Density functional theory (DFT) was employed to calculate the total energy and partial density of states (DOS) of the systems with Ta atoms adhered on different position over SiLK. Phenylene was found to play a major role and the adjacent semi-benzene rings also contribute significantly to Ta adhesion on SiLK. Based on above understanding, pore-sealing layer for p-SiLK was developed. Two groups of aniline based copolymer were synthesized by plasma enhanced chemical vapor deposition (PECVD), and their properties were investigated with SEM, SIMS and AFM analysis. Surface roughness of pore-sealing layer was found to be one of the most important factors to determine the support to Ta barrier layer. However, only preliminary results were described here. Further extensive study is needed.