Customized Chemical Compositions Adaptable for Cleaning Virtually all Post-Etch Residues

A post-etch residue cleaning formulation, based on balancing the aggressiveness of hydrofluoric acid with its well-known residue removal properties is introduced. In a series of investigations originally motivated by the cleaning challenge provided by high-k dielectric-based residues, a formulation platform is developed that successfully cleans residues resulting from the plasma patterning of tantalum oxide and similar materials while maintaining metal and dielectric compatibility. It is further shown that the fundamental advantages of this solution can be extended to the cleaning of other, more traditional post-etch residues, with no sacrifice in compatibility, as demonstrated by measurements on blanket films and through SEM data.

High Throughput Wet Etch Solution for BEOL TiN Removal

Sub-10 nm technology node manufacturing processes may require the use of thicker and denser TiN hard mask for patterning at the BEOL. The modified TiN, which tends to be more chemically robust, must be removed using a wet etch process, while maintaining typical throughput - no extension of typical wet etch process times. To satisfy these needs, a new TiN etching accelerator was found that enhanced the activity of peroxide-related species in a wet etch chemical formulation that achieved increased TiN etch rate relative to formulation without TiN etch rate accelerator (Sample 1), while also minimizing the damage to ultra-low-k inter layer dielectric (ILD) layer by a strong base, also present in the formulation. We report here the result of a solvent based formulation, which adopted the TiN etching accelerator. The formulation was able to maintain TiN etch rate and remove post-etch residue, while remaining selective to ultra-low-k ILD, Co and Cu. The TiN etch rate of the accelerator enhanced formulation can be further tuned by modifying the process temperature or the hydrogen peroxide to formulation mixing ratio and has the potential capability to process > 400 wafers.

Optimization of Cu/Low-k Dual Damascene Post-Etch Residue and TiN Hard Mask Removal

For advanced technology nodes TiN hard mask integration into Cu/low-k via/trench DD process requires the mask to be fully stripped after DD etching. The one-step H2O2 containing wet chemical clean aiming to removing TiN mask often failed to simultaneously clean etch residue. We developed more reliable two-step wet chemical process combining a solvent-based post-etch residue clean followed by a solvent/H2O2 mixture strip for TiN mask removal. Bath lifetime optimization was also demonstrated.