US Patent 7100306 Wafer guides for processing semiconductor substrates

A wafer guide includes a horizontal support panel and at least three vertical panels attached on one surface of the support panel. Each of the vertical panels has a vertical body panel and a plurality of protrusions upwardly extended from a top surface of the vertical body panel. Gap regions between the protrusions act as slots for holding wafers. Sidewalls of the slots have a convex shaped profile when viewed from a top view, and bottom surfaces of the slots also have a convex shaped profile when viewed from a cross sectional view that crosses the vertical panels.