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

Highlights: •A simple trench structure was designed in this study. •O₂ plasma irradiation on porous low-k dielectrics in the trench structure was studied. •O₂ plasma-induced damage on bottom porous low-k films was larger than that on sidewall films. •Plasma damage on sidewall porous low-k films can be mitigated by decreasing the trench width. •Plasma damage evaluation using the blanket film is a feasible method. -- Abstract: 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.