Interaction of hydrogen plasma with extreme low-k SiCOH dielectrics.

SiCOH (carbon-doped oxide) films with ultralow dielectric constants, prepared by plasma-enhanced chemical vapor deposition (PECVD), have been exposed to hydrogen plasmas on grounded or negatively biased substrates. The hydrogen plasma treatment was performed on either as-deposited or thermally annealed films. The treated films have been characterized after the different treatments by Fourier transform infrared (FTIR) spectroscopy, Rutherford backscattering and forward recoil elastic scattering analysis, and electrical measurements on metal-insulator-silicon structures. It was found that the hydrogen plasma removes CH3 fractions from the films, decreases the amounts of cage type SiO bonds, and densifies the films, thus increasing the dielectric constants. These effect were enhanced on films exposed to ion bombardment on the negatively biased substrates during the treatment in the hydrogen plasma.