Apparatus for drying batches of wafers

Abstract

Liquid is removed from batches of substrates by apparatus and methods for drying substrates that have been wet in an elongated liquid bath. The substrates are moved relative to the bath and an elongated gas-filled volume at rates of movement selected according to the location of the batches of substrates in the bath or the volume. As an example, the substrates and the bath are separated at a controlled rate to form a thin layer of liquid on each substrate as each substrate enters the gas-filled volume. The gas-filled volume is defined by an elongated hot chamber and hot gas directed into the volume and across the substrates and out of the volume continuously transfers thermal energy to the substrates. The flow rate of the gas into the volume is related to introduction of the substrates into the bath to avoid disturbing the liquid in the bath. The thermal energy transferred to the substrates in the volume evaporates the thin layer from the substrates without decreasing the rate of separation of the substrates and the bath below the maximum rate of such separation at which a meniscus will form between the bath and the surface of one of the substrates during such separation. Relative humidity in the volume is controlled by sensing the relative humidity and regulating the speed of a fan that draws gas from the volume.