Abstract: A rail is provided for use as a support in an apparatus for holding a plurality of semiconductor wafers. The rail has a plurality of teeth arranged in a vertical column, such that the space between a top surface of one tooth and a bottom surface of the next higher adjacent tooth forms a slot for receiving a portion of a semiconductor wafer. A support structure for supporting the wafer is located on the top surface of substantially all teeth that form the bottom of a slot, the support structure having sidewalls and an upper surface spaced from the top surface. On each support structure, a radius is formed at each intersection of the sidewalls and the upper surface. The support structure extends for at least approximately 50% of the length of each tooth.