Augmented reality (AR) technologies that enable the overlay of digital information on the real world are widely anticipated to be the next wave of computing platforms. For a truly immersive AR experience, the AR glasses should be lightweight, comfortable, stylish, socially acceptable, and efficient that can be worn all day. Traditional optical devices are very bulky and are not suitable for head mounted displays (HMDs) for AR glasses. Hence, there is an increasing interest in developing nano-optics based devices that are significantly smaller and lighter than the conventional devices. Materials innovation is one of the key pillars that could enable the fabrication of such lightweight devices. In this talk, the impact of new materials like highly transparent, high refractive index (HRI) substrates, litho and patterning materials for device fabrication and permanent optical materials to develop all-day wearable AR glasses will be discussed.

The ability to control the specific adsorption and packing behaviors of biomedically important proteins by effectively guiding their preferred surface adsorption configuration and packing orientation on polymeric surfaces may have utility in many applications such as biomaterials, medical implants, and tissue engineering. Herein, we investigate the distinct adhesion configurations of fibrinogen (Fg) proteins and the different organization behaviors between single Fg molecules that are mediated by the changes in the periodicity and alignment of chemically alternating nanodomains in thin films of polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) block copolymer (BCP). Specifically, the adsorption characteristics of individual Fg molecules were unambiguously resolved on four different PS-b-PMMA templates of dsa PS-b-PMMA, sm PS-b-PMMA, com PS-b-PMMA, and PS-r-PMMA. By direct visualization through high resolution imaging, the distinct adsorption and packing configurations of both isolated and interacting Fg molecules were determined as a function of the BCP template-specific nanodomain periodicity, domain alignment (random versus fully aligned), and protein concentration. The three dominant Fg adsorption configurations, SP∥, SP⊥, and TP, were observed and their occurrence ratios were ascertained on each PS-b-PMMA template. During surface packing, the orientation of the protein backbone was largely governed by the periodicity and alignment of the underlying PS-b-PMMA nanodomains whose specific direction was explicitly resolved relative to the polymeric nanodomain axis. The use of PS-b-PMMA with a periodicity much smaller than (and comparable to) the length of Fg led to a Fg scaffold with the protein backbone aligned parallel (and perpendicular) to the nanodomain major axis. In addition, we have successfully created fully Fg-decorated BCP constructs analogous to two-dimensional Fg crystals in which aligned protein molecules are arranged either side-on or end-on, depending on the BCP template. Our results demonstrate that the geometry and orientation of the protein can be effectively guided during Fg self-assembly by controlling the physical dimensions and orientations of the underlying BCP templates. Finally, the biofunctionality of the BCP surface-bound Fg was assessed and the Fg/BCP construct was successfully used in the Ca-P nanoparticle nucleation/growth and microglia cell activation.

Directed self-assembly (DSA) with block-copolymers (BCP) is a promising lithography extension technique to scale below 30nm pitch with 193i lithography. Continued scaling toward 20nm pitch or below will require material system improvements from PS-b-PMMA. Pattern quality for DSA features, such as line edge roughness (LER), line width roughness (LWR), size uniformity, and placement, is key to DSA manufacturability. In this work, we demonstrate finFET devices fabricated with DSA-patterned fins and compare several BCP systems for continued pitch scaling. Organic-organic high chi BCPs at 24nm and 21nm pitches show improved low to mid-frequency LER/LWR after pattern transfer.

Orientation control of thin film nanostructures derived from block copolymers (BCPs) are of great interest for various emerging technologies like separation membranes, nanopatterning, and energy storage. While many BCP compositions have been developed for these applications, perpendicular orientation of these BCP domains is still very challenging to achieve. Herein we report on a new, integration-friendly approach in which small amounts of a phase-preferential, surface active polymer (SAP) was used as an additive to a polycarbonate-containing BCP formulation to obtain perpendicularly oriented domains with 19 nm natural periodicity upon thermal annealing. In this work, the vertically oriented BCP domains were used to demonstrate next generation patterning applications for advanced semiconductor nodes. Furthermore, these domains were used to demonstrate pattern transfer into a hardmask layer via commonly used etch techniques and graphoepitaxy-based directed self-assembly using existing lithographic integration schemes. We believe that this novel formulation-based approach can easily be extended to other applications beyond nanopatterning.

Cylinder-forming Polystyrene-block-polycarbonate (PS-b-PC) high-chi block copolymers (BCP) were developed to extend the scaling beyond the most widely used BCP, poly(styrene-b-poly(methyl methacrylate) (PS-b-PMMA). In this work, two PC-containing BCPs, poly(styrene-b-trimethylene carbonate (PS-b-PTMC) and poly(styrene-b-methyl 5-methy1-2-oxo-1,3-dioxane-5-carboxylate) (PS-b-PMTC-Me) were synthesized using ring opening polymerization (ROP) of the cyclic carbonyl monomers from hydroxy-functional polystyrene (PS-OH) with diazabicyclo[5.4.0]undec-7-ene (DBU) as the base catalyst. Resulting BCPs were purified by fractionating in methanol:acetonitrile (MeOH:MeCN) solvent mixture to afford clean BCPs that are needed for thin-film applications. Thin-film morphologies and the orientation of the purified BCPs were determined using atomic force microscopy (AFM) analysis by coating the BCP solution on neutral underlayer modified substrates followed by short thermal annealing. It was observed that while the PS-b-PTMC domains oriented parallel to the surface, the PS-b-PMTC-Me BCP domains oriented perpendicular to the surface at similar thermal annealing temperatures without the use of topcoat or additives.

Block-copolymers (BCPs) offer the potential to meet the demands of next generation lithographic materials as they can self-assemble into scalable and tailorable nanometer scale patterns. In order for these materials to find wide spread adoption many challenges remain, including reproducible thin film morphology, for which the purity of block copolymers is critical. One of the sources of impurities are reaction conditions used to synthesize block copolymers that may result in the formation of homopolymer as a side product, which can impact the quality and the morphology of self-assembled features. Detection and characterization of these homopolymer impurities can be challenging by traditional methods of polymer characterization. We will discuss an alternate NMR-based method for the detection of homopolymer impurities in block copolymers – contrast enhanced diffusion ordered spectroscopy (CEDOSY). This experimental technique measures the diffusion coefficient of polymeric materials in the solution allowing for the ‘virtual’ or spectroscopic separation of BCPs that contain homopolymer impurities. Furthermore, the contrast between the diffusion coefficient of mixtures containing BCPs and homopolymer impurities can be enhanced by taking advantage of the chemical mismatch of the two blocks to effectively increase the size of the BCP (and diffusion coefficient) through the formation of micelles using a cosolvent, while the size and diffusion coefficient of homopolymer impurities remain unchanged. This enables the spectroscopic separation of even small amounts of homopolymer impurities that are similar in size to BCPs. Herein, we present the results using the CEDOSY technique with both first generation BCP system, poly(styrene)-b-poly(methyl methacrylate), as well as a second generation high-χ system.

To extend the scaling beyond the most widely used block copolymer (BCP), poly(styrene)-block-poly(methyl methacrylate) (PS-b-PMMA), a new organic high-chi BCP based was developed. Polystyrene-b-polytrimethylene carbonate (PS-b-PTMC) BCP was synthesized using ring opening polymerization (ROP) of trimethylene carbonate from hydroxy-functional polystyrene (PS-OH) with diazabicyclo[5.4.0]undec-7-ene (DBU) as the base catalyst. The resulting BCP was characterized by H-1 nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC) to confirm the complete chain extension of the polystyrene macroinitiator. For the DBU catalyzed BCP, the GPC trace revealed a trimodal distribution indicating the presence of coupling product and homo-PTMC impurity. Using purification techniques, homo-PTMC impurity was isolated to afford purified BCP. Thin-film morphologies of the non-purified and the purified BCPs on poly(methyl methacrylate) (PMMA) coated substrates followed by short thermal annealing were characterized using atomic force microscopy (AFM) analysis. The non-purified BCP showed island morphology with a step-height of 17 nm whereas the purified PS-b-PTMC showed a flat film with parallel cylinders of 16.4 nm pitch row-to-row distance. The ability for the PS-b-PTMC to self-assemble below 20-nm pitch resolution confirms the high interaction parameter, chi, between the PS and PTMC blocks and is a promising candidate as a high-chi BCP for directed self-assembly (DSA) application.

Direct-write 3D printing enables the fabrication of three-dimensional objects via the extrusion from a nozzle. Stimuli responsive materials that shear-thin are well-suited as inks for these 3D printing systems. Poly(isopropyl glycidyl ether)-block-poly(ethylene oxide)-block-poly(isopropyl glycidyl ether) ABA triblock copolymers were synthesized using controlled ring-opening polymerization to afford dual stimuli-responsive polymers that respond to both shear forces and temperature. These polymers were demonstrated to form hydrogels in water. The gels were observed to be thermoreversible-driven by the lower critical solution temperature of the poly(isopropyl glycidyl ether) block which helps facilitate loading of the ink into the printer syringe. Rheological studies demonstrated that the gels had a rapid and reversible modulus response to shear stress. Thus, these materials were suitable as inks for direct-write 3D printing, as they were easily extruded during printing and maintained sufficient mechanical integrity which was necessary to support the next printed layer. Printed structures of high aspect ratio pillars and stacked layers were successfully demonstrated. These types of 3D hydrogel structures may ultimately have an impact in the biomedical field for applications such as tissue engineering.

High quality block copolymers are needed for thin film self-assembly and directed self-assembly applications.

To extend scaling beyond poly(styrene-b-methyl methacrylate) (PS-b-PMMA) for directed self-assembly (DSA), high quality organic high-x block copolymers (HC series) were developed and applied to implementation of sub-10 nm L/S DSA. Lamellae-forming block copolymers (BCPs) of the HC series showed the ability to form vertically oriented polymer domains conveniently with the in-house PS-r-PMMA underlayers (AZEMBLY EXP NLD series) without the use of an additional topcoat. The orientation control was achieved with low bake temperatures (≤200 °C) and short bake times (≤5 min). Also, these process-friendly materials are compatible with existing 193i-based graphoepitaxy and chemoepitaxy DSA schemes. In addition, it is notable that 8.5 nm organic lamellae domains were amenable to pattern development by simple dry etch techniques. These successful demonstrations of high-x L/S DSA on 193i-defined guiding patterns and pattern development can offer a feasible route to access sub-10 nm node patterning technology.

A novel thin film composite (TFC) membrane featuring a polyamide bilayer was prepared on a porous polysulfone support using sequential interfacial polymerization. A conventional polyamide membrane prepared using m-phenylenediamine (MPD) in water and trimesoyl chloride (TMC) in hexane via interfacial polymerization was subsequently immersed into an alkaline aqueous solution of a hexafluoroalcohol (HFA)-containing aromatic diamine (HFA-MDA) to form an HFA-substituted aromatic polyamide layer (HFAPA) on the surface of the conventional (or reference) polyamide layer (REFPA). Water contact angle (θw) measurements indicated that the surface of the membrane becomes much more hydrophobic (θw≅140°) after forming the additional HFAPA layer onto REFPA (θw≅78°) although cross-sectional TEM images showed no significant increment in film thickness. The HFAPA-on-REFPA bilayer membrane, which features a more hydrophobic surface than the conventional REFPA membrane, exhibited improved salt rejection (ca. 50% reduction in salt passage) with a small loss in water flux (ca. 8% reduction) compared to the REFPA membrane, resulting in an excellent combination of salt rejection and water flux. Moreover, higher boron rejection was also achieved using the bilayer membrane (HFAPA-on-REFPA) compared to the REFPA membrane.