Negative Tone Imaging Process and Materials for EUV Lithography

The advantages of NTI process in EUV is demonstrated by optical simulation method for 0.25NA and 0.33NA illumination system with view point of optical aerial image quality and photon density. The extendablity of NTI for higher NA system is considered for further tight pitch and small size contact hole imaging capability. Process and material design strategy to NTI were discussed with consideration on comparison to ArF NTI process and materials, and challenges in EUV materials dedicated to NTI process were discussed as well. A new polymer was well designed for EUV-NTD process, and the resists formulated with the new polymer demonstrated good advantage of resolution and sensitivity in isolated trench imaging, and 24 nm half pitch resolution at dense C/H, with 0.3NA MET tool.