Solid State Phenomena Vols. 103-104

Abstract: This paper summarizes the process development of TiN barrier etching in presence of copper, for a thick copper level in BICMOS technology. In an industrial context, we have chosen to use a SC1 chemistry in a spin etch single wafer tool. The SC1 composition and therefore the pH level allows - the barrier to be etched with no metallic residues, ( if not clear this can be a source for shorts) - control of the selectivity between copper and TiN - control of lateral etching under copper lines, the possible source of open chains by W attack during TiN etch. The electrical results show a robust process according to current specifications, in terms of leakage and via resistance with a fresh chemistry approach. In fact, the recirculation of SC1 is not possible due to substantial concentration changes during processing, high evaporation rate of Ammonia and high decomposition rate of Peroxide in the presence of copper on surface wafer.

Abstract: Corrosion on specific Cu patterns was evaluated during Cu CMP. The corrosion was observed at isolated patterns and outer edge area of pad surrounded by oxide field after polishing and showed dependency on process. Two different commercial slurries were chosen and used for polishing after characterizing electrochemical and frictional properties. Stress simulations were conducted on these patterns. Higher stress was calculated on these patterns. The process temperature and friction behavior of Cu affected the magnitude of corrosion on Cu on these patterns.

Abstract: This paper described the development of two types of Advanced Aqueous Cleaners (AAC™) for Aluminium (Al) Post Etch Residue (PER) removal. The first approach was developed to address a need for cleaning chemistries with a smaller environmental footprint that were also able to clean at significantly lower process times and temperatures than conventional wet chemical cleans. A broad screening experiment was undertaken during which it was highlighted it was possible to clean Al lines in an acidic region though this technology was not extendable to cleaning via features. However, the study emphasised the need to use a selective alkaline reducing formulation to maintain a high cleaning efficiency for the more complex residues formed during via etch. The novel Back End Of Line (BEOL) PER cleaners presented in this paper were optimised using a statistical Design Of Experiment (DOE) to perform at lower temperatures and shorter process times and were Fluoride and organic solvent free while containing a minimum of 80%wt water.

Abstract: A Post-Etch-Residue (PER) removal process for tank and spray tools has been developed using a new inorganic aqueous based chemistry. The performance of this new type of polymer remover, Inosolv 400 Fotopur®, on process wafers is compared with other inorganic chemistries such as DSP (Dilute Sulphuric acid hydrogen Peroxide) and DSP+, containing traces of HF. Inosolv 400 Fotopur® has improved polymer removal capabilities. Furthermore Inosolv 400 Fotopur® does not show any attack of the metal or dielectric layers and is inorganic based and thus environmentally friendly.