Supercritical CO/sub 2/ for ULK/Cu integration

Supercritical CO/sub 2/ (SC CO/sub 2/) processing was investigated for porous ultra low-k dielectric (ULK) and copper for successful Back End Of Line (BEOL) integration. The introduction of specific additives into a SC CO/sub 2/ and careful control of the process parameters lends this technique to a wide range of applications: 1. Stripping: Potentially able to replace both dry ash and wet clean steps to give a single fully compatible process for ULK/Cu. The main current limitation is the removal of resins hardened during dielectric etch. 2. Cleaning: SC CO/sub 2/ is a unique candidate for a dry-in/dry-out process able to clean surface and pores of ULK materials. The removal of Cu rich residues was demonstrated with a chelating agent dissolved in SC CO/sub 2/. 3. Curing of ULK: Contamination by water and organics can significantly damaged ULK material and these can be eliminated by processing in SC CO/sub 2/. Furthermore, by introducing a suitable additive, hexamethyldisilazane (HMDS), subsequent uptake of water was prevented.