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 CH₄, H₂, NH₃ and He plasma on the properties of porous low-k material is studied. It is found that the H₂, He, NH₃ 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 CH₄ plasma can make low-k material more resist against moisture uptake and keep the k value and leakage current of low-k films stable.