Low-Cost and Self-Formed Vertical Nanowires with Aspect Ratio >100x in Deep Si-Trenches for Future 3D-LSI/IC Applications

Attempt has been made to form nanoc (NCy)ylinder structures inside Si trench and via in LSI chips by advanced directed-self-assembly. For the PS:PMMA ratio of 2:1 in PS(57k)-b-PMMA(25k) diblock-copolymer (DBC), the directed self-assembly reaction inside Si trench lead to the formation of 20 nm-width NCys and are running parallel > 6 m. It is inferred that upon increasing the molecular weight of PS to 140k from 57k, the width of NCy can be increased from 20 nm to ~70-80 nm. A ~100 nm-width metal interconnects were formed inside the ~500 nm-width vias of the bonded 3D-ICs, respectively for In metal. 2D simulation results reveal that the metal particles can be attached to PMMA of DBC and and forms cylinder. A resistance value of few tens of ohm was extracted from the I-V measurement data for In nanowires formed inside the 0.5 m vias between the flip-chip bonded LSI chips by DSA.