High-transmission attenuated PSM: benefits and limitations through a validation study of 33%, 20%, and 6% transmission masks

Abstract

Simulations indicate high transmission attenuated phase shift mask to improve resolution, reduce line end shortening, corner rounding and provide process window enhancements for some pitches. They also indicate that as the transmission is increased for line features, the Normalized image log slope (NILS) increases for all pitches. In this work the performance of33% and 20% attenuated masks has been compared against 6% and binary masks.Imaging results were obtained for l6Onm features at various pitches with a O.6NA 248nm SVGL MSIII with conventional and annular illumination. Performance ofhigh transmission in terms ofDepth ofFocus, Overlapping process windows (ODOF), Exposure latitude and Proximity effects with the various % transmissions. Critical issues such as manufacturing oftri-tone masks, Inspection, Repair and material availability for High transmission (HiT) masks will be addressed.

Application of pixel-based mask optimization technique for high transmission attenuated PSM

“…To handle these issues, we employ practical techniques based on the geometrical simplification procedure which is briefly described in [4]. The geometrical simplification approximates the raw pixel inversion results using orthogonal angles and/or octagonal angles, i.e.…”

“…Detailed experimental investigation on the application of inverse lithographical techniques for Quasar illumination with 6% as well as 30% AttPSM background was also conducted recently using AIMS TM -45 [3]. Potential benefits of high transmission schemes, such as lower mask error enhancement factor (MEEF) at dense pitches, have been well known for many years [4], but practical application of the high transmission schemes for random logic designs have been challenging, due to side-lobe printing issues. This paper will present further results of the application of pixel-based optimization technology to insert SRAF's to achieve intensity level uniformity, as well as to suppress sidelobe printing, for high transmission schemes.…”

Model-based SRAF insertion through pixel-based mask optimization at 32nm and beyond

“…The 30% case's threshold is lower than the background intensity of 0.3. The high transmission attenuated PSM schemes usually result in better exposure latitude, but do not necessarily improve depth-of-focus (DOF) [8]. Figure-5 shows the pixel inversion results for the 6% attenuated PSM case and the 30% case.…”

Lithography technology for advanced devices and introduction to integrated CAD analysis for hotspot detection

“…MoSi 2 with 6% transmission) then it is called attenuated phase shift, att-PSM. Studies show that high-transmission att-PSM help mostly in resolving dense structures [31,32]. With advanced design nodes below 45 nm the mask 3D effects have become more pronounced.…”