Investigation of CH4, NH3, H2 and He plasma treatment on porous low-k films and its effects on resisting moisture absorption and ions penetration

This paper investigates the influence of CH4, NH3, H2 and He plasma on properties of porous low-k film and its effects on resisting moisture absorption during CMP and ions penetration from sputtering. It is found that the H2, He, NH3 plasma can cause aggressive carbon depletion in the porous low-k films and change the low-k surface from hydrophobic to hydrophilic, which will induce moisture uptake into the low-k material during the CMP process, and result in increase of the k value and leakage current density. The CH4 plasma can make low-k material more resist against moisture uptake and keep the k value stable and a good electrical property of the low-k films.

After the H2, NH3 and He plasma treatments, the leakage current density of the low-k samples are all increased. After dipping into the CMP slurry, the leakage current density increases further. While for the sample after the CH4 plasma treatment, the leakage current density is almost the same as that of the original sample, and is still stable after dipping into the CMP slurry. Our experimental results reveal that CH4 plasma treatment can make low-k film more resistant against the moisture uptake and keep the electrical property of the low-k films stable.Figure optionsDownload as PowerPoint slide