Aqueous dispersion comprising inorganic particles
Inorganic particles comprised in an aqueous dispersion according to the present invention consist of agglomerates of crystalline and amorphous microparticles, and exhibit spherical and smooth surfaces. The spherical appearance, low crystallinity, and narrow particle size distribution of the inorganic particles are further advantageous in reducing scratch defects in a CMP process. In addition, since the microparticles on the inorganic particle surfaces provide more active sites and thus the removal rate is high, the inorganic particles may be advantageous as next-generation CMP polishing materials. In addition, the aqueous dispersion according to the present invention further comprises an amino acid, and the amino acid may be adsorbed on a surface of a silicon oxide wafer to strengthen electrostatic attraction between the silicon oxide wafer and the inorganic particles, resulting in an effect of further improving the removal rate.
1 . An aqueous dispersion comprising inorganic particles formed by agglomeration of a plurality of elementary particles, wherein the elementary particle has a mixed phase of a crystalline phase and an amorphous phase and has a crystallinity of 90% or less, wherein the elementary particle has a particle diameter of 1 to 50 nm.
2 . The aqueous dispersion of claim 1 , further comprising an amino acid.
3 . The aqueous dispersion of claim 2 , wherein, based on a total weight of the aqueous dispersion, a content of the amino acid is 0.01 to 5% by weight, and a content of the inorganic particles is 0.01 to 5% by weight.
4 . The aqueous dispersion of claim 2 , wherein a weight ratio of the inorganic particles and the amino acid is 100:50 to 200.
5 . The aqueous dispersion of claim 2 , wherein the amino acid is one or more selected from the group consisting of tyrosine, phenylalanine, and tryptophan.
6 . The aqueous dispersion of claim 1 , wherein the inorganic particles have a density of 3.0 to 5.0 g/ml, an average particle diameter of 30 to 1000 nm, and a standard deviation of the particle diameter of 20 or less.
7 . The aqueous dispersion of claim 1 , wherein the inorganic particles have an isoelectric point of pH 5 to 7, and pH of the aqueous dispersion is 3 to 7.
8 . The aqueous dispersion of claim 1 , wherein the inorganic particles have a surface charge of +30 to +50 mV or −30 to −50 mV of zeta potential in an aqueous dispersion state of pH 4.
9 . The aqueous dispersion of claim 1 , wherein the inorganic particles are formed of oxides of one or more elements selected from the group consisting of Ga, Sn, As, Sb, Ce, Si, Al, Co, Fe, Li, Mn, Ba, Ti, Sr, V, Zn, La, Hf, Ni, and Zr.
10 . The aqueous dispersion of claim 1 , wherein the inorganic particles are CeO 2 particles, and a Ce 3+ /Ce 4+ ion ratio is 5 to 60.
11 . The aqueous dispersion of claim 1 , wherein the aqueous dispersion is a slurry for CMP.
12 . The aqueous dispersion of claim 1 , wherein the inorganic particles are prepared by a method comprising:
(a) dissolving a self-assembling surfactant in water or a mixed solvent of water and a solvent compatible with water;
(b) preparing an inorganic precursor solution by dissolving or dispersing an inorganic precursor in the solvent before, after, or simultaneously with step (a); and
(c) forming elementary particles having a mixed phase of a crystalline phase and an amorphous phase in a shell formed by the surfactant through a self-assembly reaction of the inorganic precursor and the surfactant, and forming inorganic particles by aggregation of a plurality of the elementary particles.
13 . The aqueous dispersion of claim 12 , wherein the inorganic particles contained in the aqueous dispersion are inorganic particles of which surface charge is controlled by further comprising treating the inorganic particles obtained in step (c) with an acid and a base.
14 . The aqueous dispersion of claim 12 , wherein the self-assembling surfactant is one or more selected from the group consisting of cationic surfactants, anionic surfactants, and amphoteric surfactants having a charge capable of binding to the inorganic precursor, and has a functional group capable of condensation reaction or crosslinking reaction.
15 . The aqueous dispersion of claim 12 , wherein the functional group capable of condensation reaction or crosslinking reaction is one or more selected from the group consisting of an amide group, a nitro group, an aldehyde group, and a carbonyl group.
16 . The aqueous dispersion of claim 12 , wherein the self-assembling surfactant has a structure of the following Formula 1:
wherein, in Formula 1, R 1 and R 3 are independently hydrogen atoms, C 1 -C 10 alkyl groups, or alkoxy groups, R 2 is a substituent of Formula 2 below, and n is a number of 2 or more:
wherein, in Formula 2, R 4 and R 5 are independently hydrogen atoms, C 1 -C 10 alkyl groups, or alkoxy groups, R 6 is a C 1 -C 10 alkylene group or a single covalent bond, and * represents a connection site.
17 . An inorganic particle formed by agglomeration of a plurality of elementary particles wherein the elementary particle has a mixed phase of a crystalline phase and an amorphous phase, which satisfies one or more of (i) to (v) below:
(i) the elementary particles have a crystallinity of 90% or less;
(ii) an aspect ratio (minor axis/major axis) of the inorganic particle is 0.8 or more;
(iii) a particle diameter of the elementary particle is 20 nm or less;
(iv) a standard deviation of a particle diameter of the inorganic particle is 20 nm or less;
(v) the inorganic particle is CeO 2 particle, and a Ce 3+ /Ce 4+ ion ratio is 40 or more.