Influence of CMP Chemicals on the Properties of Porous Silica Low-k Films

This paper describes the influence of the chemical mechanical polishing (CMP) process on the degradation in the leakage currents and dielectric constants of porous silica low- films. It is found that the leakage current and dielectric constant increased by post-CMP cleaning solution due to the increase of and bonds according to Fourier transform infrared (FTIR) absorption. This is because the surfactant in the post-CMP cleaning solution permeated into the porous silica. The permeated surfactant in the porous silica can be removed by rinsing with 2-propanol or ethanol after the CMP process. Degradations of the leakage current density and dielectric constant can be recovered by ethanol rinse and subsequent 1,3,5,7-tetramethyl- cyclo -tetrasiloxane vapor treatment, which makes the pore wall surfaces hydrophobic.