The applications of wet chemical cleaning at the ‘back-end’ of Integrated Circuit (IC) or Metal-Oxide Semiconductor (MOS) fabrication are reviewed from chemical, environmental and cost perspectives. The various classes of commercially available “solvents” and “cryogenic” cleans are reviewed from the perspective of process suitability, impact on device yield and waste management. Strategies for minimizing processing concerns, as well as alternatives to organic solvent based wet chemical processing will also be discussed. Bulk photoresist (PR) stripping, post metal definition-, and post window etch cleaning are used to illustrate the discussion.
The use of radiotracing as a diagnostic tool in understanding the mechanism for metallic contamination during solvent cleans is also discussed. Data suggesting how the chemistry and solvent composition affects alkali metal (for example, sodium) contamination of dielectric- and barrier films during IC processing will also be presented.