Characterization of transparent quarter micron lines by spectral measurements with visible light

The spectral response of transparent quarter micron lines in opaque Chromium layers has been studied with visible light. These lines are design elements of binary components used in advanced optical systems for microlithography. In the current fabrication process lines of 200nm line width and more than 20 μm length are fabricated by electron beam lithography. The geometric parameters of these lines, e.g. width, length and the microstructural quality are controlled by scanning electron microscopy (SEM). In this work want to report about a new possibility to control the optical properties of quarter micron lines with respect to line width and microstructure. We have performed spectral resolved measurements with a tuneable light source in a spectral range between 450nm and 1600nm. Due to the dimensions of the quarter micron lines polarization depend transmission properties are expected. By performing polarization sensitive optical measurements we are able to distinguish quarter micron lines with different widths below the resolution limit of the classical microscopy with visible light.