Enhancing the Oxygen Plasma Resistance of Low-k Methylsilsesquioxane by H2 Plasma Treatment

The organic silsesquioxane, methylsilsesquioxane (MSQ), has a low dielectric constant because of its low film density compared to thermal oxide. However, the quality of the MSQ film is degraded by the damage caused by oxygen plasma and hygroscopic behavior during photoresist stripping. In this work, we have studied the ability of H2 plasma treatment to improve the quality of MSQ. The leakage current of MSQ decreases as the H2 plasma treatment time is increased. The dielectric constant of treated samples remains constant (∼2.7). In addition, the thermal stability of MSQ film is significantly promoted. The H2 plasma treatment can provide additional hydrogen to passivate the inner structure of porous MSQ film, and reduce the probability of moisture uptake. Therefore, H2 plasma treatment can improve the quality of low-k MSQ film and reduce the issue of photoresist stripping in the integrated process.