Patent ID: 6153044
Filing Date: 2000-11-28
Classification: G03F

Abstract:
An apparatus for protecting a surface from particle deposition, comprising:a) a thermophoretic pellicle contained within a system chamber, said thermophoretic pellicle having walls comprising a material having a high electrical and thermal conductivity, and provided with at least one gas inlet means and at least one aperture that controls the rate of outflow of a gas to maintain a region of locally high pressure within said thermophoretic pellicle relative to a lower and sub-atmospheric pressure maintained in a secondary chamber by pumping means;b) a substrate contained within said thermophoretic pellicle, said substrate having a surface to be protected from particle deposition, wherein the aperture provides line of sight access to the surface of the substrate from the system chamber, and wherein the gas inlet means and aperture are located to provide a flow of gas substantially parallel to and away from the surface of the substrate; andc) means for establishing and maintaining a temperature gradient between the surface of the substrate and the walls of said thermophoretic pellicle, wherein the surface of said substrate is warmer than the walls.