Influence of the watermark in immersion lithography process

Evaporation of water droplets on photoresist surfaces – An experimental study of contact line pinning and evaporation residues

“…[41][42][43] showed that no watermark defects occur, if droplets are removed by airjet blowing before complete evaporation, which indicates that the terminal phase of the evaporation process is the detrimental one. 44 Near complete evaporation, any dissolved components that have been leached from the photoresist [15][16][17]19,45,46 during the lifetime of the droplet are strongly enriched in concentration. Ishibashi et al performed a TOF-SIMS analysis of the drying residues of water droplets on immersion resists and found a significant enhancement of the PAG concentration.…”

Advances in Patterning Materials for 193 nm Immersion Lithography

“…Prior to exposure, water may penetrate the topcoat (often through small pinholes) and form circular blisters or induce swelling of the resist . The blister or swelling causes a lensing defect during exposure, which is exhibited by a circular region with narrower pitch. ,,,, The topcoat blister defect was predominantly observed with early base-soluble topcoats, and improvements in topcoat materials have largely eliminated this type of defect. , …”

Studies on immersion defects using mimic immersion experiments

“…Using alkaline developer soluble type top coat material, that enable to meet the leaching and the sliding angle specifications required from exposure tool suppliers, enhancement of depth-of-focus and generation of few immersion specific bubble related circular defects were observed. However, increase in bridging type and slimming type defects commonly observed in ArF dry lithography have been reported on ArF immersion lithography with top coat [7][8] and the measures for them are required.…”