Surface Control: High-x Block Copolymers for Microelectronics

Microelectronic device features continue to decrease in size,
pushing the limits of photolithography and therefore requiring increasingly
expensive multi-patterning techniques to achieve production of next generation
devices. An alternative bottom-up approach to higher resolution patterning uses
self-assembly of block co-polymers to increase the frequency of a pre-pattern image
created with traditional photolithography. We have developed silicon containing
block co-polymers as high-chi (χ) materials that allow production
of smaller features. This work focuses on a block co-polymer of poly(4-pentamethyldisilyl styrene)-b-poly(2-vinylpyridine)
(PDSS-P2VP) that was produced by anionic polymerization. This polymer has excellent
etching selectivity under both oxidative and reductive reaction ion-etching
conditions.^1,2 The χ value for PDSS-P2VP was
estimated by measuring the order-disorder transition temperature of the polymer
and found to be significantly higher than a block co-polymer that can create 10
nm patterns. Neutral top and bottom surfaces were identified by the island and hole
technique previously reported, and the block co-polymer was thermally annealed
between these layers.³ Different processing conditions, such
as O₂ plasma etch time, were adjusted to demonstrate production of
oriented 10nm lamellae.

¹ Bates C. M., et al. Science (2012), 338(6108), 775.

² Azarnouchea,
L., et al. J. Vac. Sci. Technol. B
(2016) 34 (6), 061602/1-061602/10.

³ Maher, M. J., et al. Chemistry
of Materials (2014), 26(3), 1471-1479.