Figure 5
From: Lens-free reflective topography for high-resolution wafer inspection
Surface height evaluation using a high-resolution phase image. (a) Optical microscope image of the home-made resolution test target, exhibiting patterns with bar spacing values in the range 19 − 2.4 μm. (b) and (c) Reconstructed phase images in the absence and presence of speckle illumination, respectively. (d) Line plot graphs of the positions indicated by the white dotted lines in (b) and (c). (e) Cross sectional layout of the prepared resolution test target. A line-space structure with a height \(h\) of 100 nm is etched and a layer of SiO2 with a thickness of \(2h\) is deposited on an Si substrate. (f) 3D surface plot reconstructed using the high-resolution phase image of c. For the structure with a spacing of 4.8 μm, the obtained height values are in 92.5% agreement with the reference values.
