A chemical solution spraying method for spraying a chemical solution onto canvas K1 has a loop shape in a side view while reciprocating nozzle device S along rail L extending in a width direction of canvas K1 with respect to canvas K1, in which time period Tc during which canvas K1 is in contact with wet paper X is 0.03 seconds or more, time period Tn required for nozzle device S to one-way move is 0.2 to 20 minutes, traveling speed Vp of canvas K1 is 500 m/min or more, length K of canvas K1 is 20 to 80 m, a number of times of contact N of any point on a surface of canvas K1 with wet paper X during time period Tn, time period Tn, traveling speed Vp, and length K satisfy a relationship of N=(Tn.Math.Vp)/K, under predetermined conditions.

Embodiments relate to surface treating a substrate, spraying precursor onto the substrate using supercritical carrier fluid, and post-treating the substrate sprayed with the precursor to form a layer with nanometer thickness of material on the substrate. A spraying assembly for spraying the precursor includes one or more spraying modules and one or more radical injectors at one or more sides of the spraying module. A differential spread mechanism is provided between the spraying module and the radical injectors to inject spread gas that isolates the sprayed precursor and radicals generated by the radical injectors. As relative movement between the substrate and the spraying assembly is made, portions of the substrate is exposed to first radicals, sprayed with precursors either one of the spraying modules or both spraying modules using supercritical carrier fluid, and then exposed to second radicals again.