Published online by Cambridge University Press: 10 February 2011
Recent studies have shown that extremely dilute HCl mixtures can offer considerable cost savings and improved particle performance relative to traditional SC2 formulations. This work indicates, however, that extreme levels of dilution are not necessary to secure many of the benefits suggested for dilute HCI. Significant benefit can be attained by pursuing moderate concentration and temperature alterations. In this study, an intermediate dilution and temperature reduction are evaluated to assess potential production advantage. Comparison of a 1:1:20 formulation at 60 C is made to a more traditional 1:1:6 mixture at 85 C. The impact of the chemistry and temperature alteration on peroxide decomposition rate is shown to be dramatic. While initial pour-up ratios suggest that the dilute recipe could require 1/3 as much peroxide as the traditional chemistry, chemical savings are significantly more dramatic due to the ability of the solution to maintain concentration over time. An additional benefit associated with the alternative pour-up is a marked reduction in particle levels on silicon surfaces; particle levels on thermal oxide wafers have not shown the same trend. VPD-ICPMS measurements are used in this study to illustrate that the recipe change results in comparable metallic removal efficiency.