Damage-Free Cryogenic Aerosol Clean Processes

Cryogenic aerosol clean processes have been successful for cleaning of blanket films and robust device structures. As the line width becomes smaller and aspect ratios (ARs) become higher, they have either been eliminated or used with caution due to line damage. Theoretical line damage modeling indicates that collision induced stress in line structures is a function of the AR of line cross section. Theoretical analysis also shows that smaller and lighter cryogenic aerosol crystal is desired to avoid line damage. Nitrogen cryogenic aerosol processes have been evaluated for damage-free cleaning on 90 and 65 nm technologies at the IBM 300 mm manufacturing line. Process results on the 90 nm technology at the post spacer nitride deposition clean have shown no damage and particle removal efficiency (PRE) greater than 92%. Implementation of the same nitrogen only aerosol process at the post cobalt silicide probe test clean on 90 nm high AR gate structures has shown significant improvement over the previous process of record argon/nitrogen-based aerosol. Evaluation at the post nickel silicide probe test clean on 65 nm device technology with low AR gate structures has shown the process is damage-free with particle removal efficiency greater than 95%. This nitrogen only aerosol process has been implemented in the 65 nm technology flow and has been proven to be damage-free in volume manufacturing