Wet Cleaning of Ru Semi-Damascene 18 MP Structures

Cleaning of semi-damascene structures after direct metal etch (DME) are becoming more challenging as the size of features are getting smaller and number of materials increase in advanced nodes. Typical DME residues in-between Ru lines, generated during/after semi-damascene patterning by DME, mainly consist of Ti-based residues whereas there are TiN layers present as etch stop layer (ESL) below the SiN HM and underneath Ru lines. Wet cleaning of Ti-based residues selective to TiN and Ru in a decent process time is necessary. Undercut of TiN during wet cleaning results in collapsing of the SiN HM and/or Ru lines. We present a novel FOTOPUR ® R solution designed to clean Ti-based residues selective to Ru and TiN. Moreover, the new chemistry can further extend the process window without collapsing the Ru lines.