A Frequency Multiplication Technique Based on EUV Near-Field Imaging

摘要

We present a simulation study of the near-field Extreme Ultraviolet (EUV) imaging technique to break the diffraction limit of conventional lithography for spatial frequency multiplication. Rigorous electromagnetic simulations are performed to investigate the near-field EUV imaging performance and its process capability. An optical index, depth of thickness fluctuation (DOT) is defined to characterize the tolerable variation of the imaging-layer thickness, which plays a key role in evaluating the feasibility of this lithography technology. High sensitivity of the near-field image (profile and amplitude) to both absorber CD and propagation depth is found in transverse-electric (TE) and transverse-magnetic (TM) illumination modes. Despite the attractive prospect of applying this near-field imaging technique for semiconductor manufacturing, technical challenges from its optical performance and process control are non-trivial.