Measurements on both serpentine and fork-fork metallized structures showed good electrical yield, indicating of a low number of stochastic defects, according to imec. The e-test results confirmed the capability of the High NA EUV lithography scanner and its surrounding ecosystem to pattern lines/spaces at such a small dimension.
Last year imec was the first to present industry-relevant logic and DRAM structures patterned in a single High NA EUV lithography exposure step. As a next step, imec is now showing that metallized line structures of 20nm pitch, obtained after single High NA EUV patterning using metal oxide (MOR) negative tone resist, exhibit more than a 90% yield.
This metric was obtained on two different test structures, i.e., serpentine (or meander) structures and fork-fork structures, designed to reveal information on stochastic defectivity.
Commenting Steven Scheer, senior vice president R&D at imec, said, “This is the first ever electrical yield demonstration of 20nm pitch metal lines obtained with single High NA EUV patterning. These results represent an initial validation of the capabilities of High NA EUV lithography and its surrounding ecosystem, including advanced resists and underlayers, photomasks, metrology techniques, (anamorphic) imaging strategies, optical proximity correction (OPC), as well as integrated patterning and etch techniques.
“We will continue working with our patterning ecosystem on processes to drive further yield improvement and transfer of these technologies to our manufacturing partners.”
The imec-ASML High NA EUV ecosystem includes partners such as leading chip manufacturers, material and resist suppliers, mask suppliers, and metrology experts, all working together to develop and optimise High-NA EUV lithography for next-generation semiconductor manufacturing at the sub-2 nm node.
“E-testing is a key step in High-NA EUV validation,” added Philippe Leray, director of the advanced patterning department at imec. “These e-test results also show us the way forward. When combined with e-beam inspection, conductivity measurements of metallized serpentine and fork-fork structures give information on the stochastic defects (i.e., breaks and bridges, respectively) that lead to reduced yield. These insights support our ecosystem partners in the development of strategies to mitigate stochastic defects.
“One of our ongoing efforts is focused on optimising resist performance in terms of dose-to-yield reduction with minimal impact on stochastic failures, an effort we are making in close collaboration with the resist community.”
