Substrate processing apparatus, substrate processing method and substrate processing liquid

A substrate processing method comprising:

• processing a substrate in a substrate processing bath by wet etching with a substrate processing liquid comprising phosphoric acid, water, ketone, and an oxidizing agent. wherein the ketone is liquid at 20° C., has vapor pressure of 30 mmHg or less at 20° C., and has viscosity of 1.0 cP or less at 20° C.;
• discharging the substrate processing liquid from the substrate processing bath to a circulating flow channel, heating the substrate processing liquid flowing through the circulating flow channel at a temperature between 50° C. and 90° C., and supplying the substrate processing liquid again from the circulating flow channel to the substrate processing bath to circulate the substrate processing liquid under heating;
• and
• purifying the heated substrate processing liquid with a filter in a purifying module provided on the circulating flow channel, wherein
• a concentration of the phosphoric acid in the substrate processing liquid is 50 to 95 wt %,
• a concentration of the water in the substrate processing liquid is 4 to 49.5 wt %,
• a concentration of the ketone in the substrate processing liquid is 0.5 to 15 wt %, and
• a concentration of the oxidizing agent in the substrate processing liquid is 0.1 to 10 wt %.