Optimizing Polymer Brush Coverage To Develop Highly Coherent Sub-5 nm Oxide Films by Ion Inclusion

Abstract

Area-selective deposition is a promising technique for positional self-alignment of materials at a prepatterned surface. Critical to this is the development of molecular systems that have selective surface binding and can act as templates to material growth. This paper reports how end functionalized polymers can be used to create oxide films through a grafting method. Here, we detail a facile approach for rapid grafting (in seconds) of polymer brush films with complete coverage over large areas with high uniformity (pinhole free). Subsequent conversion to an oxide (∼3−4 nm thickness) is performed via liquid-phase metal ion infiltration. Exposing the covalently grafted polymer brush (P2VP-OH) to a metal salt-solvent solution (using the Al 3+ ion as a model species) swells the polymer, facilitating ion inclusion. Early results suggest that a solvent-mediated approach to polymer film infiltration can be used to develop inorganic films in a facile process. While data shows inclusion into both large-area and patterned films, the mechanism and understanding of these have been limited. In particular, the solution-mediated process described here shows the precise tailoring of nanometer-thin polymer films that are pinhole-free and that can be activated to create semiconductor-compatible oxide films that are parallel in quality to ALD-or CVD-derived processes. A surface deactivation strategy is also realized using a hydroxyl-terminated polystyrene (PS-OH) brush that prevents the deposition of ions. We consider this strategy as a means to prevent electromigration of ions as well as the possibility of coating ALD layers.

Green Nanofabrication Opportunities in the Semiconductor Industry: A Life Cycle Perspective

“…Presently BCPs and polymer brushes are selected based on their ability to produce high quality patterned substrates for specific applications such as in the semiconductor industry. To enable the transition of BCPs and polymer brushes from “lab to fab” research efforts have focused on finding suitable BCPs with controllable ordination of the phase separated domains and long-range alignment and polymer brushes with high uniformity (pinhole free) complete coverage over large areas and tuneable thickness [ 18 , 69 ]. However, it is worth considering the importance of green polymer chemistry and the potential of this new technology to be environmentally friendly if toxic moieties are substituted for biocompatible materials.…”

“…It is the chemical incompatibility of the BCP blocks that enables self-assembly into a variety of morphologies [ 13 , 14 , 15 ]. The molecular mechanisms of ASD and DSA technologies must be better understood before these techniques can be integrated into semiconductor manufacturing processes [ 11 , 16 , 17 , 18 ].…”

Analysing trimethylaluminum infiltration into polymer brushes using a scalable area selective vapor phase process

“…Samples were prepared as outlined in the work published by R. Lundy and P. Yadav et al and summarized here. 21 Native oxide silicon substrates were placed in a tetrahydrofuran (THF) bath and ultrasonicated for 20 minutes before being oxygen plasma treated for -OH group termination. The polymer powders were dissolved into a solution (THF for P2VP and P4VP, toluene for PS) of 0.2 wt.%.…”

“…The substrate temperature was additionally kept below the polymer degradation temperature (P2VP ≈ 320 °C, P4VP ≈ 290 °C PS ≈ 260 °C). 21 All depositions (with the exception of P4VP in part of experiment 4) took place above the bulk glass transition temperature (T g ) of the polymers (P2VP ≈ 100 °C, P4VP ≈ 150 °C, PS ≈ 100 °C). 51,52 The chamber was kept pumped in such a way that the pressure was maintained at 26.7 Pa (200 mTorr) for this stage.…”

“…PS systems are well established for achieving area deactivation to prevent material growth in ASD/BCP processes in ALD and other infiltration methods. 16,20,21 Thorough discussion of the practicalities of pyridine based polymers as infiltration media are described elsewhere, [21][22][23][24][25][26] however, to summarize, both P2VP and P4VP have favourable characteristics for use as area activation media in ASD and BCP lithography. Due to the nitrogen lone pair located in the pyridine ring ( Figure 1a), both poly-vinyl pyridines (PVPs) can facilitate metal coordination bonding.…”