10nm 2^nd generation BEOL technology with optimized illumination and LELELELE

10-nm 2nd-generation BEOL technology is described with an optimized illumination system and multi-patterning lithography. While the optimized illumination system offered a possibility to pattern reduced metal pitches in the preferred orientation, difficulties of T-T and T-S patterning still remained. It was overcome by increasing the number of available multi-patterning colors from 2 to 4. First-ever implementation of LELELELE with tight inter-color misalignment control increased scalability up to 17.1% and was demonstrated with SRAM 128 Mb yield.