Abstract: The inventive substrate treatment apparatus includes a spin chuck which horizontally holds and rotates a wafer; a heater which is disposed in opposed relation to a lower surface of the wafer held by the spin chuck and heats the wafer from a lower side; a phosphoric acid nozzle which spouts a phosphoric acid aqueous solution to a front surface (upper surface) of the wafer held by the spin chuck; and a suspension liquid nozzle which spouts a silicon suspension liquid to the front surface of the wafer held by the spin chuck. The wafer is maintained at a higher temperature on the order of 300° C. and, in this state, a liquid mixture of the phosphoric acid aqueous solution and the silicon suspension liquid is supplied to the front surface of the wafer.