SRAM, NAND, DRAM contact hole patterning using block copolymer directed self-assembly guided by small topographical templates

Sublithographic patterning using Directed Self-Assembly (DSA) is demonstrated for practical circuits with non-periodic features. The DSA of irregularly distributed contact holes is guided by small topographical templates patterned by immersion 193 nm optical lithography. We experimentally demonstrate flexible and precise DSA control of 25 nm contact holes (centroid deviation∼1 nm) guided by 66 nm guiding templates for industry-standard 22-nm SRAM cells. Solution are also proposed to pattern contact holes (CD∼15 nm, Pitch∼40 nm, σ∼2 nm) for 15-nm NAND with two-hole templates and 2×-nm DRAM with three-hole templates. DSA is a low-cost, high-throughput extension of the double-patterning technique.