Self-assembly of polystyrene-block-poly(4-vinylpyridine) block copolymer on molecularly functionalized silicon substrates: fabrication of inorganic nanostructured etchmask for lithographic use

Abstract

Block copolymers (BCPs) are seen as a possible cost effective complementary technique to traditional lithography currently used in the semiconductor industry. This unconventional approach has received increased attention in recent years as a process capable of facilitating the ever decreasing device size demanded. Control over microdomain orientation and enhancing long range order are key aspects for the utility of BCPs for future lithographic purposes. This paper provides an efficient route for the fabrication of highly ordered nanostructures suitable for such application. We investigate the significant effect of surface treatment regarding the self-assembly process of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) by employing an ethylene glycol layer, producing well defined perpendicular P4VP cylinders with long range order over large surface areas. Nanopores are generated through surface reconstruction using a preferential solvent, which allows for the incorporation of an inorganic moiety. Treatment of this pattern with UV/Ozone leads to formation of well-ordered iron oxide nanodots with a pitch of $26 nm. Furthermore, high aspect ratio silicon nanopillars result following pattern transfer (using Ar/O 2).

Formation of sub-7 nm feature size PS-b-P4VP block copolymer structures by solvent vapour process

“…Immersing the thin film in ethanol leads to form nanoporus film in hexagonal nanodot arrays 34 . For lamellar structure, the reconstruction cause swelling of lamella and eventually may hamper the structure.…”

Strategies for Inorganic Incorporation using Neat Block Copolymer Thin Films for Etch Mask Function and Nanotechnological Application

“…[ 129 ] Of late, hemispherical Fe 3 O 4 nanodots were utilized as catalysts for germanium nanowire growth that possessed coherent twin boundaries perpendicular to the nanowire growth direction. [ 157 ] Thus far, Fe 3 O 4 , [ 129,138,139 ] CeO 2 , [ 128,131 ] CuO, [ 128 ] and Al 2 O 3 [ 139,140 ] patterning of nanodot and nanowire features have been developed using the metal salt inclusion methodology and have been shown to be effective on-chip etch masks on silicon (see examples in Figure 13 and Table 2 ). Fe 3 O 4 inclusion has been shown to be effective in a low molecular weight lamellar PS-b -P4VP system for line space features with a pitch of ≈10 nm.…”

“…In initial works, iron oxide(s) (Fe 3 O 4 and Fe 2 O 3 ) nano dot arrays were created over large areas following spin coating of a metal nitrate ethanolic solution. [ 126,138 ] Following deposition of the metal salt precursors by spin coating, ultraviolet/ozone treatment is carried out to remove the remaining polymer matrix material and oxidize the nitrate precursors to form metal oxide features as shown in Figure 12 d-f. Others have recently adopted a similar approach to form oxides and then thermally annealed fi lms post metal precursor deposition to remove the polymer template. [ 156 ] In 2008, Park et al [ 142 ] demonstrated silica nanodots and nanowires following spin-coating of a PDMS precursor in selective solvents on surface reconstructed PS-b -P4VP fi lms.…”

“…[ 158 ] Silicon nanopillars of 500 nm in height can be obtained following ICP etching of metal oxide nanodot patterns. [ 127,129,138 ] Additionally, nanowires were developed in the same way for both BCP systems, PS-b -PEO and PS-b -P4VP, resulting in highly uniform Fe 3 O 4 nanowires with 42 nm (PS-b -PEO) [ 134 ] and 32 nm (PS-b -P4VP) [ 139 ] periodicity. We have also integrated the metal-salt inclusion technique in graphoepitaxy schemes with similar effi cacy in PS-b -P4VP for patterning aligned Si and Ge nanofi ns as shown in Figure 14 .…”

Parallel Arrays of Sub-10 nm Aligned Germanium Nanofins from an In Situ Metal Oxide Hardmask using Directed Self-Assembly of Block Copolymers

“…[17][18][19] Likewise, metal oxide inclusion has been reported to significantly enhance 2 "activated" PS-b-PEO and PS-b-P4VP BCP systems for Si nanofeature fabrication. [20][21][22][23] In order to extend the relentless dimensional scaling of semiconductor features (i.e. Moore's Law) to the deep nanoscale regime (< 10 nm), employing DSA of BCP nanopatterns has emerged as a cost-effective route to controllably fabricate device-relevant features on a wafer scale level.…”