AN OPTICAL FOCUS SENSOR, AN INSPECTION APPARATUS AND A LITHOGRAPHIC APPARATUS

摘要

An optical focus sensor, an inspection apparatus and a lithographic apparatus is provided to generate the focus error signal which generates at the location of the substrate about the focal plane of the objective lens by utilizing the optics focus sensor. The scatterometer comprises the detector(18) detecting the reflected spectrums and the radiation projector(2) reflecting on the substrate(W). The detector communicates with the processing unit(PU). The radiation source is focused through the interference filter and polarizer(17). The reflected radiation is focused through the objective lens(15) on the top of substrate. The reflected radiation is transferred to the detector through the semi-reflective surface. The reflected radiation is imaged on the detector. The beam splitter sends the light beam portion of the reflected radiation beams by the optics focus sensor. The optics focus sensor generates the output signal(S) provided to the control unit adjusting the location of the substrate about the objective lens.