Abstract: A method for cleaning a substrate of the present invention, in which a plurality of substrates are placed substantially parallel with each other are dipped into a cleaning solution to remove particles adhering to each of the substrates, includes the step of dipping the substrates into the cleaning solution at a speed (V) through a surface of the cleaning solution, wherein the speed (V) for dipping the substrates into the cleaning solution, a minimum distance (l) among distances between the substrates, a length (L) of the substrates measured in a dip direction thereof, and a speed (v) at which the particles are transferred along the surface of the cleaning solution in a vertical direction with respect to back faces of the substrates satisfy the expression: lV.gtoreq.vL.

Abstract: An apparatus for washing a wafer, having a wafer-washing tank holding a washing liquid and receiving a wafer, a washing-liquid inlet provided in a first part of the sidewall of the tank, a washing-liquid outlet provided in a second part of the sidewall of the tank opposite to the first part of the sidewall, and a device holding the wafer in the tank so that the wafer is parallel to the level of the washing liquid when the wafer is immersed into or positioned in the washing liquid in the tank, and a device producing an essentially horizontal flow of the washing liquid in the tank. A process for washing a wafer, having the steps of producing a horizontal flow of the washing liquid in the tank, immersing a wafer cassette holding the wafer into the washing liquid in the tank so that the wafer is parallel to the level of the washing liquid in the tank, and subsequently positioning the cassette in the washing liquid in the tank so that the wafer is parallel to the level of the washing liquid in the tank.