| 摘要 |
Method of determining stray radiation, Lithographic Projection Apparatus A method of determining a stray radiation condition of a projection system, with numerical aperture NA, of a lithographic projection apparatus comprises the steps of providing a detector with a detector aperture coincident with the image plane of the projection system, performing a measurement of a reference parameter in accordance with the projection beam intensity, performing a measurement of a stray radiation parameter of an image of an isolated feature, formed by the projection system; and calculating a coefficient, representative of the stray radiation condition of the projection system, on the basis of the measured stray radiation parameter and the reference parameter, whereby the extent of the detector aperture fits within the extent of a notional shape which is defined by first scaling down the shape of said feature by the magnification factor of the projection system, and by subsequently displacing each line element constituting the edge of the scaled down shape, parallel to itself, over a distance of at least NA in a direction perpendicular to that line element, and by further comprising a positioning step whereby the detector aperture is positioned within the image of the isolated feature.
|
