The Active Role of Etch Products in Particle Removal by SC-1 Solutions

摘要

According to the conventional model for particle removal van-der-Waals bonded Si_3N_4 particles should be easily removed by conventional SC-1. With a thin water layer between particles and substrate they are already perfectly undercut and electrostatic repulsion should lead to particle removal. However, this forecast is in strong contrast to the experimental results presented here. Only in the presence of silica etch products in the SC-1 mixture can these particles be detached. To cause this effect the van-der-Waals force between Si_3N_4 particle and the silica surface has to be lowered by some kind of adaptation layer. That the wafer etch products could act in this way is consistent with very low van-der-Waals interactions of silica in water [3]. Therefore the particle removal model in alkaline solutions has to be extended by the active role of the wafer-etch products for lowering van-der-Waals forces.