3D Metrology of sub-60 nm Isolated Lines Using TSOM Optical Method

R. Attota, R.G. Dixson
NIST, US

Keywords: nanometrology, TSOM, nanocharacterization, optical microscope, through-focus

Summary:

In the current world of nanotechnology, fast and reliable 3D measurement of nanoscale features is extremely useful. Furthermore, it if the analytical tools used are cost effective and have high throughput–such as optics-based tools. In this paper we utilize a novel optical technique called the TSOM (through-focus scanning optical microscope) method that produces sub-nanometer scale dimensional measurement sensitivity using a conventional optical microscope–by analyzing images obtained at different focus positions–enabling 3D analysis of isolated lines. Using this method we have experimentally demonstrated nanometer scale sensitivity to sidewall angle variations of isolated lines using a conventional optical microscope with 546 nm illumination wavelengths. In addition we could also experimentally identify a difference of 0.8 nm in the linewidth of isolated lines. This methodology has potential utility for a wide range of target geometries and application areas, including nanotechnology, biotechnology, nanomanufacturing, and semiconductor process control. In the current paper using both simulations and experiments we present size and shape (3D) evaluation of isolated nanoscale lines using the TSOM method.