The effects of pH adjustors in post Cu CMP cleaning solutions on particle adhesion and' removal

Abstract

The interaction force of silica and alumina particles on Cu wafer and effect of pH adjuster were theoretically and experimentally investigated in post Cu CMP cleaning solutions. The zeta potential of y-alumina significantly decreased when pH of solutions increased with TMAH (tetra methyl ammonium hydroxide), MEA (mono-ethanolamine) and EDA (ethylene diamine). However, the zeta potential of fumed silica particle was not changed much in these solutions. TMAH solution with higher alkaline pH was more desirable chemistry for cleaning Cu surfaces. The strongest repulsive force was calculated between abrasive particles and Cu surface in solution with addition of TMAH at pH 12. The higher pH, the more repulsive interaction forces between particles and Cu surfaces were calculated. © 2005 The Electrochemical Society.