Silica-based composite fine-particle dispersion, method for producing same, and polishing slurry including silica-based composite fine-particle dispersion

1. A dispersion liquid of a silica-based composite particle, containing a silica-based composite particle that has a core particle mainly composed of amorphous silica, and bound thereto a ceria particle mainly composed of crystalline ceria, the ceria particle further having on the surface thereof a silica film, the silica-based composite particle having an average particle size of 50 to 350 nm, and having features [1] to [4] below:

[1] the silica-based composite particle has a mass ratio of silica and ceria of 100:60 to 316;

[2] the silica-based composite particle when measured by X-ray diffractometry allows detection of a crystal phase of ceria only;

[3] the silica-based composite particle when measured by X-ray diffractometry is found to have a crystallite size of crystalline ceria on the (111) plane of 10 to 25 nm; and

[4] the silica-based composite particle is partially covered with the silica film,

wherein the dispersion is designed to give a streaming potential curve when subjected to cation colloidal titration, from which ratio (ΔPCD/V) of the amount of change of streaming potential (ΔPCD), and the amount of consumption (V) of a cation colloidal titrant at a knick, given by Equation (1) below, is determined to be −110.0 to −15.0:

Δ PCD/V =( I−C )/ V   Equation (1)

where,

C: streaming potential (mV) at knick; and

I: streaming potential (mV) at start point of streaming potential curve; and

V: amount of consumption (ml) of cation colloidal titrant at knick.

2. The dispersion liquid of a silica-based composite particle of claim 1 , wherein the silica-based composite particle, when determined by energy dispersive X-ray spectroscopy (EDS) measurement that selectively irradiates electron beam on the silica film observable under a transmission electron microscope, is found to have a ratio of Si atomic percentage relative to Ce atomic percentage (Si atomic percentage/Ce atomic percentage) of 0.9 or larger.

3. The dispersion liquid of a silica-based composite particle of claim 2 , wherein the silica-based composite particle contains impurities whose content rates satisfy (a) and (b) below:

(a) the content rate of each of Na, Ag, Al, Ca, Cr, Cu, Fe, K, Mg, Ni, Ti, Zn and Zr is 100 ppm or below; and

(b) the content rate of each of U, Th, Cl, NO 3 , SO 4 and F is 5 ppm or below.

4. The dispersion liquid of a silica-based composite particle of claim 2 , showing a negative streaming potential before being titrated, when kept within the range from pH 3 to 8.

5. A polishing slurry comprising the dispersion liquid of a silica-based composite particle described in claim 2 .

6. The dispersion liquid of a silica-based composite particle of claim 1 , wherein the silica-based composite particle contains impurities whose content rates satisfy (a) and (b) below:

(a) the content rate of each of Na, Ag, Al, Ca, Cr, Cu, Fe, K, Mg, Ni, Ti, Zn and Zr is 100 ppm or below; and

(b) the content rate of each of U, Th, Cl, NO 3 , SO 4 and F is 5 ppm or below.

7. The dispersion liquid of a silica-based composite particle of claim 6 , showing a negative streaming potential before being titrated, when kept within the range from pH 3 to 8.

8. A polishing slurry comprising the dispersion liquid of a silica-based composite particle described in claim 6 .

9. The dispersion liquid of a silica-based composite particle of claim 1 , showing a negative streaming potential before being titrated, when kept within the range from pH 3 to 8.

10. A polishing slurry comprising the dispersion liquid of a silica-based composite particle described in claim 9 .

11. A polishing slurry comprising the dispersion liquid of a silica-based composite particle described in claim 1 .

12. The polishing slurry of claim 11 , designed to be used for planarizing a semiconductor substrate having a silica film formed thereon.

13. A method of manufacturing a dispersion liquid of a silica-based composite particle, the method comprising Step 1 to Step 3 below:

Step 1: keeping a silica particle dispersion liquid, having a silica particle dispersed in a solvent, stirred at a temperature of 5 to 98° C., and at a pH of 7.0 to 9.0, and adding thereto a metal cerium salt in a continuous or intermittent manner, to thereby obtain a precursor particle dispersion liquid containing a precursor particle;

Step 2: drying the precursor particle dispersion liquid, followed by calcination at 400 to 1,200° C., subjecting the obtained calcined product to treatment (i) below, to thereby obtain a dispersion liquid of the disintegrated calcined product:

(i) wet disintegration/grinding under addition of a solvent, conducted at pH 8.6 to 10.8,

and,

Step 3: centrifuging the dispersion liquid of the disintegrated calcined product at a relative centrifugal acceleration of 300 G or larger, and removing a precipitated component, to thereby obtain a dispersion liquid of a silica-based composite particle.

14. The method of manufacturing a dispersion liquid of a silica-based composite particle of claim 13 , wherein the silica-based composite particle contains impurities whose content rates satisfy (a) and (b) below:

(a) the content rate of each of Na, Ag, Al, Ca, Cr, Cu, Fe, K, Mg, Ni, Ti, Zn and Zr is 100 ppm or below; and

(b) the content rate of each of U, Th, Cl, NO 3 , SO 4 and F is 5 ppm or below.