Surface treatment method, method for producing semiconductor substrate including the surface treatment method, composition for surface treatment, and system for producing semiconductor substrate including the composition for surface treatment
The present invention provides a means capable of sufficiently removing a residue containing inorganic oxide abrasive grains present on the surface of a polished object to be polished containing silicon nitride. One aspect of the present invention relates to a surface treatment method for reducing a residue containing inorganic oxide abrasive grains on a surface of a polished object to be polished containing silicon nitride using a composition for surface treatment, wherein the composition for surface treatment contains a zeta potential adjusting agent having a negatively charged functional group and having a viscosity of an aqueous solution having a concentration of 20% by mass at 25° C. of 10 mPa·s or more and a dispersing medium, and the surface treatment method includes controlling a zeta potential of the silicon nitride and a zeta potential of the inorganic oxide abrasive grains each to −30 mV or less using the composition for surface treatment.
1. A surface treatment method for reducing a residue comprising inorganic oxide abrasive grains on a surface of a polished object to be polished comprising silicon nitride using a composition for surface treatment, wherein
the composition for surface treatment comprises a zeta potential adjusting agent having a negatively charged functional group and having a viscosity of an aqueous solution having a concentration of 20% by mass at 25° C. of 10 mPa·s or more and a dispersing medium, and
the surface treatment method comprises controlling a zeta potential of the silicon nitride and a zeta potential of the inorganic oxide abrasive grains each to −30 mV or less using the composition for surface treatment.
2. The surface treatment method according to claim 1 , wherein the inorganic oxide abrasive grains comprise cerium oxide abrasive grains, and a zeta potential of the cerium oxide abrasive grains is controlled to −30 mV or less using the composition for surface treatment.
3. The surface treatment method according to claim 1 , wherein the residue further comprises polyurethane, and the surface treatment method further comprises controlling a zeta potential of the polyurethane to −10 mV or less using the composition for surface treatment.
4. The surface treatment method according to claim 1 , wherein the zeta potential adjusting agent is a polymer having an anionic group and having a weight average molecular weight of 1,000 or more.
5. The surface treatment method according to claim 4 , wherein the polymer having an anionic group has at least one functional group selected from the group consisting of a sulfonic acid (salt) group, a sulfuric acid (salt) group, a phosphonic acid (salt) group, a phosphoric acid (salt) group, and a carboxylic acid (salt) group.
6. The surface treatment method according to claim 1 , wherein the composition for surface treatment further comprises a pH adjusting agent.
7. The surface treatment method according to claim 1 , wherein a pH value of the composition for surface treatment is 2 or more and less than 5.
8. The surface treatment method according to claim 1 , wherein the surface treatment method is a rinse polishing treatment method or a cleaning treatment method.