Compensation for imaging errors in EUV lithography

In this paper we will examine some of the fundamental imaging effects that must be considered with the intended implementation of Extreme Ultraviolet Lithography (EUVL). The paper will show how simulation can be used to examine issues such as image placement and the effect of mask dimension errors. We will show how the exact structure of an EUV mask need not be simulated, but the use of Fourier boundary conditions may be used as an accurate substitute, considerably speeding up computation time. Further, this technique is used to show the positional error that is inherent in an off-axis reflective optic design such as that proposed for EUV exposure tools. Any dimension error that is produced on the mask will not linearly transfer to the printed wafer, this is known as Mask Error Factor (MEF). We will present simulation data showing that the off-axis nature of the incident light leads to different rates of change of printed CD, at defocus, for features orientated perpendicular to each other. These effects must then be taken into account when we consider reticle error budget for EUVL technology.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.