Surface modification of porous low-k material by plasma treatment and its application on reducing the damage from sputtering and CMP process

The influence of CH
₄
, H
₂
, NH
₃
and He plasma on the properties of porous low-k material is studied. It is found that the H
₂
, He, NH
₃
plasma can cause huge carbon depletion in the porous low-k material, 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 results in the increase of the k value and leakage current. The CH
₄
plasma can make low-k material more resist against moisture uptake and keep the k value and leakage current of low-k films stable.