APPARATUS AND METHOD FOR HIGH RATE UNIFORM COATING, INCLUDING NON-LINE OF SIGHT

摘要

A direct vapor deposition (DVD) apparatus and method is taught, that provides a carrier gas flow entraining vapor atoms for the coating of regions on a substrate that are not in line-of-sight. The degree of non line-of-sight (NLOS) coating, hence thickness uniformity around the substrate is a sensitive function of the flow conditions. For a fixed background pressure in the region of deposition, an increase in the uniformity of the coating thickness is accomplished as the flow velocity is reduced. This improvement in uniformity is a result of an increase in the fraction of vapor atoms which deposit in NLOS positions on the substrate such as backside (21) of fiber (65) as indicated by vapor streamlines (51). Vapor impact width (VIW) is the width of the vapor flux impacting on some area of the fiber. Front side coating (FSC) width is the vapor width of atoms impacting on the substrate frontside (22).