Comparison of O2 Plasma Treatment on Porous Low Dielectric Constant Material in Sidewall and Bottom of Trench Structure

The degradation induced by oxygen (O₂) plasma irradiation to the porous low dielectric constant materials (low-k; k=2.5) has been investigated in this study. The impact in the sidewall and bottom of the trench was compared by designing a special structure to simulate the real trench structure. From the experimental results, the low-k films in both sidewall and bottom of the new-designed trench structure shows a worse electrical performance and reliability after performing O₂ plasma treatment. Moreover, the low-k films in the sidewall of the trench structure suffer a less damage in comparison to those samples in the bottom. Furthermore, as the width of the trench is scaled-down, the O₂ plasma damage on the sidewall low-k films can be alleviated due to a reduced flux of oxygen active species. While the plasma damage on the bottom low-k films have no impact for trench width effect. Therefore, the scaled trench geometry would not cause more serious degradation for the low-k films under O₂ plasma treatment with an identical treatment condition. The blanket film can be used to monitor the plasma damage for the next technology generation since the bottom low-k films have the worse impact under plasma treatment. Furthermore, this new-designed trench structure can easily analyses the low-k material degradation in the sidewall of the trench structure.