Sidewall restoration of porous ultra low-k dielectrics for sub-45nm technology nodes

Plasma ashing and etching integration steps on porous ultra low-k (ULK) have been investigated and are found to damage the porous dielectric structural and electrical properties, leading to weak performance and reliability. In order to overcome these integration issues, an ULK restoration step is proposed. This work discuss the effect of hexamethyldisilazane (HMDS: (CH"3)"3-Si-NH-Si-(CH"3)"3) based treatment performed on a porous ULK material. The treatment reveals a beneficial effect on the sidewalls restoration as well as a gain in the IMD electrical performances after integration.