The polishing liquid according to the embodiment comprises abrasive grains, an additive and water, wherein the abrasive grains satisfy either or both of the following conditions (a) and (b). (a) Producing absorbance of at least 1.50 for light with a wavelength of 400 nm in an aqueous dispersion with a content of the abrasive grains adjusted to 1.0 mass %, and also producing light transmittance of at least 50%/cm for light with a wavelength of 500 nm in an aqueous dispersion with a content of the abrasive grains adjusted to 1.0 mass %. (b) Producing absorbance of at least 1.000 for light with a wavelength of 290 nm in an aqueous dispersion with a content of the abrasive grains adjusted to 0.0065 mass %, and also producing light transmittance of at least 50%/cm for light with a wavelength of 500 nm in an aqueous dispersion with a content of the abrasive grains adjusted to 1.0 mass %.

The polishing liquid according to the embodiment comprises abrasive grains, an additive and water, wherein the abrasive grains satisfy either or both of the following conditions (a) and (b). (a) Producing absorbance of at least 1.50 for light with a wavelength of 400 nm in an aqueous dispersion with a content of the abrasive grains adjusted to 1.0 mass %, and also producing light transmittance of at least 50%/cm for light with a wavelength of 500 nm in an aqueous dispersion with a content of the abrasive grains adjusted to 1.0 mass %. (b) Producing absorbance of at least 1.000 for light with a wavelength of 290 nm in an aqueous dispersion with a content of the abrasive grains adjusted to 0.0065 mass %, and also producing light transmittance of at least 50%/cm for light with a wavelength of 500 nm in an aqueous dispersion with a content of the abrasive grains adjusted to 1.0 mass %.

The polishing liquid according to the embodiment comprises abrasive grains, an additive and water, wherein the abrasive grains include a tetravalent metal element hydroxide, and produce a liquid phase with a nonvolatile content of 500 ppm or greater when an aqueous dispersion with a content of the abrasive grains adjusted to 1.0 mass % has been centrifuged for 50 minutes at a centrifugal acceleration of 1.5910.sup.5 G.

The polishing liquid according to the embodiment comprises abrasive grains, an additive and water, wherein the abrasive grains include a tetravalent metal element hydroxide, and produce a liquid phase with a nonvolatile content of 500 ppm or greater when an aqueous dispersion with a content of the abrasive grains adjusted to 1.0 mass % has been centrifuged for 50 minutes at a centrifugal acceleration of 1.5910.sup.5 G.

A polishing liquid includes abrasive grains, an additive and water, wherein the abrasive grains include a tetravalent metal element hydroxide, and produce a liquid phase with a nonvolatile content of 500 ppm or greater when an aqueous dispersion with a content of the abrasive grains adjusted to 1.0 mass % has been centrifuged for 50 minutes at a centrifugal acceleration of 1.5910.sup.5 G.

A polishing liquid includes abrasive grains, an additive and water, wherein the abrasive grains include a tetravalent metal element hydroxide, and produce a liquid phase with a nonvolatile content of 500 ppm or greater when an aqueous dispersion with a content of the abrasive grains adjusted to 1.0 mass % has been centrifuged for 50 minutes at a centrifugal acceleration of 1.5910.sup.5 G.

A polishing liquid includes abrasive grains, an additive and water, wherein the abrasive grains include a tetravalent metal element hydroxide, and produce a liquid phase with a nonvolatile content of 500 ppm or greater when an aqueous dispersion with a content of the abrasive grains adjusted to 1.0 mass % has been centrifuged for 50 minutes at a centrifugal acceleration of 1.5910.sup.5 G.

A polishing liquid includes abrasive grains, an additive and water, wherein the abrasive grains include a tetravalent metal element hydroxide, and produce a liquid phase with a nonvolatile content of 500 ppm or greater when an aqueous dispersion with a content of the abrasive grains adjusted to 1.0 mass % has been centrifuged for 50 minutes at a centrifugal acceleration of 1.5910.sup.5 G.

An etching gas composition includes at least two C.sub.3 or C.sub.4 organic fluorine compounds and niobium fluoride, and the at least two C.sub.3 or C.sub.4 organic fluorine compounds are isomers.

An etching gas composition includes at least two C.sub.3 or C.sub.4 organic fluorine compounds and niobium fluoride, and the at least two C.sub.3 or C.sub.4 organic fluorine compounds are isomers.