Image quality and pattern transfer in directed self assembly with block-selective atomic layer deposition
(Color online) Schematic cross-sectional views of the block-selective infiltration process. (a) Self-assembled PS-b-PMMA block copolymer film. Repeated (b) TMA and (c) water precursor exposures form alumina within PMMA domains. (d) Oxygen plasma strip of organic material. (e) Plasma etch transfer to underlying substrate. (f) Chemical removal of alumina mask.
(Color online) Top–down SEM images of (a) 41 nm pitch and (b) 27 nm pitch self-assembled PS-b-PMMA lamellar patterns. (i) and (iii) PS-b-PMMA films infiltrated with alumina using 1, 3, 5, and 7 TMA/water cycles and (ii) and (iv) remaining alumina patterns formed using 1, 3, 5, and 7 cycles after O2 plasma removal of organic material.
(Color online) (a) Plot of pattern CD (in units of L 0) vs number of TMA/water infiltration cycles for (blue circles) 41 nm pitch and (green squares) 27 nm pitch patterns. Dashed line represents the critical dimension of the initial polymer pattern. (b) and (c) Circularly averaged power spectral density of (b) 41 nm pitch and (c) 27 nm pitch self-assembled patterns after 0, 1, 3, 5, and 7 TMA/water infiltration cycles. Curves are offset intentionally for clarity. The arrows above the 7-cycle curve in (c) point to an increase in amplitude at frequencies not present in the original pattern. These broad features reflect the merged lines observed after polymer removal.
(Color online) 80° angle cross-sectional SEM images of aluminum oxide patterns formed by infiltrating 41 nm (left side) and 27 nm pitch (right side) PS-b-PMMA patterns. (a) 1 TMA/water cycle, (b) 3 TMA/water cycles, (c) 5 TMA water cycles. (d) Plot of alumina pattern thickness vs number of TMA/water cycles for (blue circles) 41 nm and (green squares) 27 nm pitch patterns.
(Color online) (a) and (b) TEM cross sections of 27 nm pitch PS-b-PMMA pattern after (a) 1 cycle and (b) 3 cycles TMA/water exposure. (c)Elemental map of aluminum content during lateral scan along 27 nm pitch PS-b-PMMA pattern after 3 cycles TMA/water exposure. (d) Elemental scan of aluminum (green squares), Pt (solid circles), and Si (open circles) content traversing film thickness.
(a) 80° angle cross-sectional SEM images after (a)plasma etch transfer to silicon and (b) after wet etch removal of remaining aluminum oxide mask. (c) Top–down and (d) 80° angle cross-sectional SEM images of electron-beam directed assembly and pattern transfer to silicon.
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