Particle adsorption behaviors during solvent cleaning containing NH4F

• We clarified particle adsorption behaviors on metal lines during cleaning with a solvent containing NH4F.
• EDX analysis detected metallic particles, and polymeric particles on the metal line after the solvent clean.
• IPA rinse prevented the metallic particle adsorption, but it enhanced the polymeric particle adsorption.
• Importance of a flow of liquid during rinsing was discussed.
• Ionized Cu in an aqueous solution and electrically-charged polymeric particle could be adsorbed.

Particle adsorption behaviors on to metal lines during cleaning with a solvent containing ammonium fluoride (NH4F) were studied. In this experiment, a conventional batch spin wet tool was used for the cleaning process after dry etching of metal line patterning. Energy dispersive X-ray spectroscopy (EDX) analysis detected metallic particles showing a strong Cu signal (Cu particle) at the wafer center area, and also detected polymeric particles showing strong fluorine and carbon signals (FC particle) at the wafer edge area after solvent clean. Both types of particle were found on the metal lines. An isopropyl alcohol (IPA) rinse prevented the Cu particle growth, but enhanced the FC particle adsorption.

Figure optionsDownload as PowerPoint slide