METHOD AND APPARATUS FOR HIGH-SPEED THICKNESS MAPPING OF PATTERNED THIN FILMS

摘要

An apparatus or method captures reflectance spectrum for each of a plurality of spatial locations on the surface of a patterned wafer. A spectrometer system having a wavelength-dispersive element receives light reflected from the locations and separates the light into its constituent wavelength components. A one-dimensional imager scans the reflected light during translation of the wafer with respect to the spectrometer to obtain a set of successive, spatially contiguous, one-spatial dimension spectral images. A processor aggregates the images to form a two-spatial dimension spectral image. One or more properties of the wafer, such as film thickness, are determined from the spectral image. The apparatus or method may provide for relatively translating the wafer at a desired angle with respect to the line being imaged by the spectrometer to enhance measurement spot density, and may provide for automatic focusing of the wafer image by displacement sensor feedback control. The spectrometer system may include an Offner optical system configured to twice pass light reflected from the wafer and received by the imager.