As the semiconductor chip size continues to decrease, extreme ultra violet lithography (EUVL) is becoming a vital technology to achieve the high resolution patterning required for sub-7 nm node technologies. The patterning resolution of EUVL is highly dependent on the performance of EUV photoresists (PR) which can lead to variations in the patterning process and affects the overall quality of the semiconductor. Although there are several traditional methods to determine a patterning performance of PR, it becomes more challenging as scale tighten. To this end, we develop a new analysis method, named ‘W-curve’, defining EUV PR resolution using ADI SEM images, that visualizes micro-bridge and -break defect cliffs and local CD uniformity at the same time. Using W-curve method, 3 different PR performance at 36 nm-pitch line/space pattern was clearly distinguished. Also, the obtained result was well correlated with time-series trend data and electric test data. Therefore, we believe that W-curve method could provide a new insight for understanding EUV PR performance and improve patterning performance in a facile and versatile manner.
For many years traditional 193i lithography has been extended to the next technology node by means of multi-patterning techniques. However recently such a 193i technology became challenging and expensive to push beyond the technology node for complex features that can be tackled in a simpler manner by the Extreme UltraViolet Lithography (EUVL) technology. Nowadays, EUVL is part of the high-volume manufacturing device landscape and it has reached a critical decision point where one can push further the single print on 0.33NA full field scanner or move to a EUV double patterning technology with more relaxed pitches to overcome current 0.33NA stochastic limits. In this work we have selected the 28nm pitch dense line-space (P28) as critical decision check point. We have looked at the 0.33NA EUV single print because it is more cost effective than 0.33NA EUV double patterning. In addition, we have conducted a process feasibility study as P28 in single print is close to the resolution limit of the 0.33NA EUV full field scanner. We present the process results on 28nm dense line-space patterning by using Inpria’s metal-oxide (MOx) EUV resist. We discuss the lithographic and etching process challenges by looking at resist sensitivity, unbiased line edge roughness (LER) and nano patterning failures after etching (AE), using broad band plasma (BBP) and e-beam (EB) defectivity inspection tools. To get further understanding on the P28 single patterning capability we have integrated the developed EUV MOx process in a relevant iN7 technology test vehicle by developing a full P28 metallization module with ruthenium. In such a way we were able to carry on electrical tests on metallized serpentine, fork-fork and tip-to-tip structures designed with a purpose of enabling further learning on pattern failures through electrical measurements. Finally, we conclude by showing the readiness of P28 single exposure using Inpria’s MOx process on a 0.33NA EUV full field scanner.
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