Comparison of O2 plasma treatment on porous low dielectric constant material at sidewall and bottom of trench structure

The degradation induced by oxygen (O2) plasma irradiation to the porous SiCOH materials with a dielectric constant of 2.56 (porous low-k) has been investigated in this study. The plasma damage on porous low-k films at the sidewall and bottom of the trench structure was compared by the design of a simple trench structure. Experimental results indicated that O2 plasma irradiation degrades the electrical characteristics and reliability of porous low-k films at the sidewall and bottom of a trench structure. Porous low-k films at the bottom of the trench structure suffer more from O2 plasma irradiation than those at the sidewall. As the width of the trench structure is reduced, O2 plasma induced-damage on the porous low-k films at the bottom remains unchanged, while that damage on those at the sidewall is mitigated owing to a reduction of the flux of active oxygen species. Therefore, O2 plasma-induced damage on porous low-k films is not increased as the trench structure is miniaturized. Finally, a blanket film can be feasibly used to monitor plasma damage on porous low-k films because a plasma process has a detrimental effect on low-k films at the bottom of a trench structure.