Highly Dispersed Fe3+-Substituted Colloidal Silica Nanoparticles for Defect-Free Tungsten Chemical Mechanical Planarization

作者：Kim Kijung; Seo Jihoon; Lee Myeongjae; Moon Jinok; Lee Kangchun; Yi Dong Kee^*; Paik Ungyu

来源：ECS Journal of Solid State Science and Technology, 2017, 6(7): P405-P409.

DOI：10.1149/2.0171707jss

Silica nanoparticles (NPs) are used as abrasives for tungsten chemical mechanical planarization (CMP) at acidic pH. However, the use of silica NPs at pH near their isoelectric point remains a problem because agglomeration due to low surface charge leads to defects on the tungsten surface during CMP. Herein, we report a simple strategy to increase the surface charge of silica NPs at acidic pH for defect-free tungsten CMP. The isomorphic substitution of Si4+ by Fe3+ ions on the surface of silica NPs by hydrothermal reaction led to a pH-independent permanent negative surface charge, which increased as the concentration of substituted Fe3+ ions increased. At acidic pH, the increased negative surface charge of Fe3+-substituted silica (Fe-silica) NPs resulted in a reduction in the number of agglomerated large particles relative to that of pure silica NPs. As a result, highly negatively-charged Fe-silica NPs showed high performance in the reduction of defect count on the tungsten surface after CMP.

• 出版日期2017