| 摘要 |
Applicants have discovered that if scattered light from an etched workpiece is measured over many orders of diffraction, important characteristics of the etched workpiece can be correlated with the principal component content of the intensity characteristic. An etched workpiece (10) is inspected by exposing the workpiece to a beam of coherent light (31) measuring the intensity of the light (33) scattered from the workpiece over a range of spatial frequencies corresponding to a plurality of diffraction orders, determining the principal component content of the intensity envelope of the tested workpiece and accepting or rejecting the workpiece in accordance with whether or not the principal component content satisfies predetermined criteria. In preferred embodiments the principal components are determined in relation to a plurality of reference measurements by singular value decomposition. <IMAGE> |
