Polishing solution and polishing method
Polishing liquid comprising abrasive grains, a phosphonic acid compound having a molecular weight of 210 or more, and at least one selected from the group consisting of amino acids and amino acid derivatives, in which a silanol group density of the abrasive grains is 6.5 groups/nm 2 or less, and a degree of association of the abrasive grains is 1.5 or more.
1. A polishing liquid comprising:
abrasive grains;
a phosphonic acid compound having a molecular weight of 210 or more; and
at least one selected from the group consisting of amino acids and amino acid derivatives, wherein
a silanol group density of the abrasive grains is 6.5 groups/nm 2 or less,
a degree of association of the abrasive grains is 2.2 or more,
a pH is 6.0 or less, and
the polishing liquid has a property that, when used for polishing surfaces of silicon nitride and silicon dioxide, a ratio of polishing rate of silicon nitride with respect to a polishing rate of silicon dioxide is in a range of 0.80 to 1.20.
2. The polishing liquid according to claim 1 , wherein the abrasive grains contain colloidal silica.
3. The polishing liquid according to claim 1 , wherein a zeta potential of the abrasive grain is positive.
4. The polishing liquid according to claim 1 , wherein a pH is 2.0 to 5.0.
5. The polishing liquid according to claim 1 , wherein the polishing liquid is configured to be used for polishing a surface to be polished containing silicon dioxide, silicon nitride, and polysilicon.
6. The polishing liquid according to claim 1 , wherein the polishing liquid has a property that, when used for polishing surfaces of polysilicon and silicon dioxide, a ratio of polishing rate of polysilicon with respect to a polishing rate of silicon dioxide is in a range of 0.80 to 1.20.
7. The polishing liquid according to claim 6 , wherein a content of the abrasive grains is less than 3.0% by mass based on the total mass of the polishing liquid.
8. The polishing liquid according to claim 6 , wherein the phosphonic acid compound contains 2-phosphonobutan-1,2,4-tricarboxylic acid.
9. The polishing liquid according to claim 1 , wherein the polishing liquid has a property that, when used for polishing surfaces of silicon nitride, polysilicon and silicon dioxide, a ratio of polishing rates of silicon nitride and polysilicon with respect to a polishing rate of silicon dioxide is 0.80 or more and less than 1.20.
10. The polishing liquid according to claim 1 , wherein a content of the abrasive grains is less than 3.0% by mass based on the total mass of the polishing liquid.
11. The polishing liquid according to claim 1 , wherein the phosphonic acid compound contains 2-phosphonobutan-1,2,4-tricarboxylic acid.
12. A polishing method comprising a step of polishing a surface to be polished containing silicon dioxide, silicon nitride, and polysilicon using the polishing liquid according to claim 1 .