Recent Progress in E-Beam Lithography for SEM Patterning

An improved e-beam lithography technique has been developed to generate a high quality micro/nano-scale random speckle pattern on various specimens for metrology and characterization of specimens using Scanning Electron Microscope (SEM) images with Digital Image Correlation (DIC) for image analysis. In this application, a mathematical algorithm has been integrated into the e-beam control system to greatly reduce the time for etching a dual-layer photo-resist coating to obtain a random distribution with optimal size distribution in the resulting pattern. It was determined that the thickness of photo-resist must be carefully controlled to obtain the desired pattern spot size after completing the development process. The resulting beam lithography technique has been employed by the authors to obtain high quality Au random pattern ranging from 150nm to 500nm on Al and Si specimens.

In addition to the local application of high quality random pattern, the authors developed a marker-placement methodology so that the local pattern area could be readily located through specimen translations. Extension of the approach to the production of high quality 50nm pattern on silicon wafer using various metals (e.g., Al, Ti, Ni, Cu, Zn, W, Ag, Pt) is in progress.