Improving uniformity of 3-level High Aspect Ratio Supervias

High aspect-ratio (AR) 3-level Supervias (SV), with a minimum bottom CD of 12.1 nm, AR = 9.4 and with > 93 % electrically active SV are successfully integrated in a Back-End of Line (BEOL) test vehicle with Metal Pitch 36. 3-level SV directly connects M
x
with M
X+3
metal layers, without connecting to the intermediate two metal layers and is a potential scaling booster for future technology nodes. An SiOCH material (low-k) is chosen as the main dielectric layer, and barrierless Ru as metal. Supervias are patterned following a SV-first, dual damascene integration flow. In this work, the effect of the trench etch in the already patterned SV is explored, and an improved dual damascene process is proposed. The goal is to enhance the electrical yield while keeping high aspect ratios with low bottom CD, to keep Supervias relevant for future advanced nodes.