Silicon dioxide particle dispersion for grinding and grinding composition

Abstract

This invention aims to provide a silicon dioxide particle dispersion, a grinding composition, and a grinding method for use in CMP polishing of wafers, which maintains a high polishing speed while suppressing the formation of scratches. The invention provides a silicon dioxide particle dispersion comprising silicon dioxide particles and water, characterized in that the silicon dioxide particles exhibit a weight loss rate of 2.5% or less at 200°C to 700°C, and the number of spherical foreign objects with an equivalent circular diameter of 0.48 μm or more and a shape factor SF1LP of less than 1.50, as measured by either method A or method B, is 25 or less. Method A involves adding pure water to the aforementioned dispersion and diluting it to a silica concentration of 0.1% by mass (30g). The solution is then filtered through a filter with an absolute pore size of 0.4 μm (filtration area 1.8 cm²). This filter is then observed using a scanning electron microscope (SEM) at 5000x magnification (area 448 μm²) for 20 fields of view. The equivalent circle diameter of the aforementioned spherical foreign object is calculated using image analysis. Furthermore, the length of the longest straight line connecting any two points on the contour line of the spherical foreign object (LLP), representing the particle's maximum diameter, is used as the basis for determining the shape factor SF1LP. The ratio of the area of ​​the circle with this diameter to the projected area SLP of the aforementioned spherical foreign object (LLP² × π / 4) / SLP is defined as the shape factor SF1LP. Method B involves adding pure water to the aforementioned dispersion and diluting it to a silicon dioxide concentration of 0.03% by mass (30g). After filtering through a filter with an absolute pore size of 0.4μm (filtration area of ​​1.8cm2), the filter is magnified to 5000x field of view (area of ​​448μm2) using a scanning electron microscope (SEM). When observing 67 fields of view, the equivalent circle diameter of the aforementioned spherical foreign object is calculated using image analysis. Furthermore, the length of the longest straight line connecting any two points on the contour line of the spherical foreign object, i.e., the maximum diameter LLP of the particle, is used as the ratio of the area of ​​the circle with the diameter to the projected area SLP of the aforementioned spherical foreign object (LLP2×π / 4) / SLP, which is defined as the shape factor SF1LP.

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