A roller cover and associated pair of cams attachable to opposite ends of the roller cover. Each of the cams has an outer diameter extending radially outwardly beyond an outer diameter of the roller cover a predetermined distance for maintaining the outer diameter of the roller cover a corresponding distance from the surface being coated during rotational movement of the roller cover over the surface to act as a thickness gauge for the coating being applied to the surface.

The present disclosure provides a method for roller-coating a liquid material, including roller-coating the liquid material on a silicon wafer with a liquid coating roller, and controlling a thickness of the liquid material carried on the liquid coating roller with a liquid taking roller, where a liquid retaining structure is provided at two ends of the liquid coating roller and/or two ends of the liquid taking roller, and the liquid retaining structure is configured to prevent the liquid material from flowing out from the two ends of the liquid coating roller and the two ends of the liquid taking roller.

The present disclosure provides a method for roller-coating a liquid material, including roller-coating the liquid material on a silicon wafer with a liquid coating roller, and controlling a thickness of the liquid material carried on the liquid coating roller with a liquid taking roller, where a liquid retaining structure is provided at two ends of the liquid coating roller and/or two ends of the liquid taking roller, and the liquid retaining structure is configured to prevent the liquid material from flowing out from the two ends of the liquid coating roller and the two ends of the liquid taking roller.