Etching, ashing and cleaning are very essential processes in semiconductor manufacturing. During these processes porous low dielectric constant (low-k) materials can be heavily damaged with a concomitant increase in dielectric properties. Fourier transform infrared spectroscopy (FTIR) measurements of the nanoporous films exposed to these manufacturing processes show that the methyl groups in these films were replaced by the silanol group during the plasma process. The highly polar silanol group increases the film's dielectric constant and makes the film more hydrophilic. In this work, supercritical carbon dioxide (SCCO2) with hexamethyldisilazane (HMDS) is used as a potential treatment to fix the plasma-damaged porous low-k films. Comparing the FTIR spectra for the films before and after SCCO2/HMDS treatment shows that it was successful in replacing silanol groups with methyl groups. The dielectric constant of the films was measured before and after the plasma treatment, as well as before and after the SCCO2/HMDS treatment, using CV measurements on a metal/insulator/semiconductor (MIS) structure. The dielectric constant of the plasma-damaged films was 3.71. When the sample was treated with SCCO2/HMDS, the dielectric constant decreased to 2.49. The dielectric constant and the FTIR measurements of the SCCO2/HMDS treated samples are comparable to those of the undamaged films.
B. Lahlouh, Dr. T. Rajagopalan, Lubguban, J., Biswas, N., Gangopadhyay, S., Sun, J., Huang, D. H., Simon, S. L., Toma, D., and Butler, R., “Supercritical Carbon Dioxide/Hexamethyldisilazane Treatment of Plasma-Damaged Low Dielectric Constant Films”, in APS Meeting Abstracts, 2003.