Analysis on Threshold Energy of Particle Removal in Spray Cleaning Technology

In the manufacturing of semiconductor devices, the reduction in the physical strength of device structures due to scaling has caused the problem of pattern collapse by the physical force required for removing particles. A novel advanced spray technology has been developed to accurately and tightly control the droplet size and velocity. The influence of droplet characteristics on particle removal was quantitatively investigated using this technology. It was observed that the amount of removed particles was linked to the droplet energy density on the wafer. The threshold energy to remove particles was analyzed and the relationship between particle removal and pattern damage generation was determined. Finally the process window, which is a particle removable area without pattern collapse, was clearly revealed by the gap between the particle removal and the damage threshold curves.