Slurry, and polishing method
A slurry containing abrasive grains and a liquid medium, in which the abrasive grains include first particles and second particles in contact with the first particles, a particle size of the second particles is smaller than a particle size of the first particles, the first particles contain cerium oxide, the second particles contain a cerium compound, and in a case where a content of the abrasive grains is 0.1% by mass, an absorbance for light having a wavelength of 380 nm in a liquid phase obtained when the slurry is subjected to centrifugal separation for 5 minutes at a centrifugal acceleration of 5.8×10 4 G exceeds 0.
1. A slurry comprising abrasive grains and a liquid medium, wherein
the abrasive grains include first particles and second particles in contact with the first particles,
a particle size of the second particles is smaller than a particle size of the first particles,
the first particles contain cerium oxide,
the second particles contain a cerium compound, and
in a case where a content of the abrasive grains is 0.1% by mass, an absorbance for light having a wavelength of 380 nm in a liquid phase obtained when the slurry is subjected to centrifugal separation for 5 minutes at a centrifugal acceleration of 5.8×10 4 G exceeds 0.
2. The slurry according to claim 1 , wherein the cerium compound contains cerium hydroxide.
3. The slurry according to claim 1 , wherein a content of the abrasive grains is 0.01 to 10% by mass.
4. The slurry according to claim 1 , wherein the slurry is used for polishing a surface to be polished containing silicon oxide.
5. A polishing method comprising a step of polishing a surface to be polished by using the slurry according to claim 1 .
6. The slurry according to claim 1 , wherein a particle size of the first particles is 100 nm or more.
7. The slurry according to claim 1 , wherein a particle size of the second particles is 30 nm or less.
8. The slurry according to claim 1 , wherein an average particle size of the abrasive grains is 120 nm or more.
9. The slurry according to claim 1 , wherein a content of cerium oxide in the abrasive grains is 50 to 95% by mass on the basis of the entire abrasive grains.
10. The slurry according to claim 1 , wherein a content of cerium hydroxide in the abrasive grains is 5 to 50% by mass on the basis of the entire abrasive grains.
11. The slurry according to claim 1 , wherein a content of the abrasive grains is 0.01 to 0.5% by mass.
12. The slurry according to claim 1 , wherein a light transmittance for light having a wavelength of 500 nm in a liquid phase obtained when the slurry is subjected to centrifugal separation for 5 minutes at a centrifugal acceleration of 5.8×10 4 G is 50%/cm or more.
13. The slurry according to claim 1 , wherein pH is 2.0 to 7.0.
14. The slurry according to claim 1 , wherein pH is 3.0 to 5.0.
15. The polishing method according to claim 5 , wherein the surface to be polished contains silicon oxide.