Abstract A mechanism of alkaline flooding to improve recovery for viscous oils was found to be related to the transition of emulsions from low viscosity and low water-oil-ratios (WORs) to high viscosity and high WORs. Distinct behaviors of emulsions formed by alkaline brines and acidic, viscous oils were experimentally observed by mixing alkaline brines and oils at different WOR. Depending on the oil type and the brine formulation, different transition behaviors of the emulsions were observed. In some cases, low viscosity oil-in-water (O/W) emulsions were observed at low WOR while high viscosity water-in-oil (W/O) emulsions were observed at high WOR. This transition of emulsion type and properties was associated with significant uplift in recovery by alkaline flooding over water flooding as observed in sandpack floods. Meanwhile, when the emulsions did not exhibit transitional behaviors and remained the same type with varying WOR, the incremental recovery by alkaline flooding was very small, regardless of whether the viscosities of the emulsions were high or low. A novel mechanism associated with flow re-direction and sweep efficiency improvement was proposed and validated using micromodel experiments. Results of this work lead to new opportunities and screening criteria to apply alkaline flooding for viscous, acidic oils.

Shales spanning a range of thermal maturity (~0.6 to >4.5%Re) were examined by high resolution transmission electron microscopy (HRTEM) in order to characterize the occurrence of turbostratic carbon nanostructures. Such structures, termed Basic Structural Units (BSU), were found in both demineralized and whole-rock samples. Highly aromatic turbostratic nanostructures found in a pre-oil window shale were verified by electron energy loss spectroscopy (EELS). Turbostratic nanostructures increase in abundance with increasing thermal maturity with their greatest frequency occurring in high maturity (>3.6%R), natural and artificially matured organic rich shales that exhibit anomalously high electrical conductivity in well logs. We hypothesize that these turbostratic carbon nanostructures initially form upon oil generation, increase in frequency with increasing thermal maturation, and eventually become numerous enough to establish mutual contact, either directly or through graphene-like sheets, so that the shale becomes conductive on a macroscopic scale.

Reverse-tone Step and Flash Imprint Lithography (S-FIL/R) requires materials that can be spin coated onto patterned substrates with significant topography and that are highly-planarizing. Ideally, these planarizing materials must contain silicon for etch selectivity, be UV or thermally curable, have low viscosity, and low volatility. One such novel material in particular, a branched and functionalized siloxane (Si-12), is able to adequately satisfy the above requirements. This paper describes a study of the properties of epoxy functionalized Si-12 (epoxy-Si-12) as a planarizing layer. An efficient synthetic route to epoxy-Si-12 was successfully developed, which is suitable and scalable for an industrial process. Epoxy-Si-12 has a high silicon content (30.0 %), low viscosity (29 cP @ 25 °C), and low vapor pressure (0.65 Torr @ 25 °C). A planarizing study was carried out using epoxy-Si-12 on trench patterned test substrates. The material showed excellent planarizing properties and met the calculated critical degree of planarization (critical DOP), which is a requirement for a successful etch process. An S-FIL/R process using epoxy-Si-12 was demonstrated using, an ImprioR 100 (Molecular Imprints Inc., USA) imprint tool. The results indicate that epoxy-Si-12 works very well as a planarizing layer for S-FIL/R.

One of the major concerns with nanoimprint lithography is defecivity. One source of process specific defects is associated with template separation failure. The addition of fluorinated surfactants to the imprint resist is an effective way to improve separation and template lifetime. This study focuses on the development of new reactive fluorinated additives, which function as surfactants and also have the ability to chemically modify the template surface during the imprint process and thereby sustain a low surface energy release layer on the template. Material screening indicated that the silazane functional group is well suited for this role. The new reactive surfactant, di-(3,3,4,4,5,5,6,6,7,7,8,8,8- tridecafluorooctyl)silazane (F-silazane) was synthesized and tested for this purpose. The material has sufficient reactivity to functionalize the template surface and acceptable stability (and thus shelf-life) in the imprint formulation. Addition of F-Silazane to a standard imprint resist formulation significantly improved template release performance and allowed for significantly longer continuous imprinting than the control formulation. A multiple-imprint study using an Imprio® 100 tool confirmed the effectiveness of this new additive.

The use of conventional thermally cross-linked materials in advanced lithography and nano-imprinting techniques, such as negative photo resist, anti reflective coatings and planarizing layers, does not guarantee that a high degree of planarization will be obtained. Additionally, iso-dense thickness biases can create problems by narrowing process latitudes. This presentation focuses on the correlation between simulated and experimental analyses and how planarization is affected. The factors we have identified that influence a material's planarizing capability are; coating spin speed, spin time and the relationship between the solvent concentration of the material and it's via filling properties. Through optimization of these factors, an appreciable reduction in via topography was achieved. Based on our results, novel, UV cross-linkable materials have been developed and optimized for improving planarity in via applications.

This study focuses on the correlation between simulation and experiment using UV curable gap fill materials for global planarization in advanced lithographic and nanoimprinting techniques. A novel gap fill material has been optimized and developed for global planarization properties. Gap fill materials planarize irregular substrates such as patterned steps, vias, and trenches to increase depth of focus and patterning resolution. After planarizing the substrate surface, the gap fill materials provide dry etching selectivity to the under-layer to avoid damaging the dielectric materials. In the characterization of UV curable gap fill materials, two key factors were identified. The factors were the specific dependence of planarization on the spin speed and film thickness. By optimizing these factors, an appreciable reduction in via topography was realized. An array of 1.1 μm deep, 300 nm diameter holes was planarized to 10 nm thickness bias with a 380 nm thick planarizing film. In addition of global planarization, a final design consideration was to reduce the amount of outgassing during the process. UV curable gap fill material was optimized for sublimate reduction resulting in a defect-free coating. The sublimate produced from the developed gap fill material during baking was significantly decreased when compared with that produced from a thermal curable material. And, the third evaluation of UV curable gap fill materials was reported, to avoid resist poisoning issues in an advanced via-first dual damascene process. The resist poisoning properties in UV curable gap fill material were observed better performance than that of thermal curable material. The resulting UV curable gap fill materials based on this study will be extremely useful for lithographic and nanoimprinting techniques.

The term nanoimprint lithography (NIL) describes a number of processes used to form nanoscale structures by molding or embossing. Step and flash imprint lithography (S-FIL, a trademark of Molecular Imprints, Inc.) is a variant of NIL that can be performed at room temperature and low pressure. In S-FIL, a low-viscosity liquid imprint material is hardened in a patterned template by exposure to UV light. S-FIL is ideally suited to integrated-circuit device fabrication. Materials development for S-FIL has progressed significantly since its introduction in 1999. We discuss the status of materials development, with specific emphasis on the imprint material and functional materials, template fabrication and release layers, and S-FIL process variations.

Reverse-tone step and flash imprint lithography (SFIL-R) shows promise as a cost-efficient, high-resolution patterning technique; however, the generation of satisfactory patterns requires the successful application of a planarizing topcoat over topography through spincoating. Photopolymerizable nonvolatile fluids are ideal topcoat materials because they planarize better than volatile fluids during spincoating and can continue to level after spincoating. Fluid mechanics analyses indicate that complete planarization using capillary force is slow. Therefore, defining the acceptable or critical degree of planarization (DOPcrit) becomes necessary. Finite difference simulation of the spincoat and post-spin leveling processes was used to determine the planarization time for various topographic and material property combinations. A new material, Si-14, was designed to have ideal planarization characteristics (low viscosity-15.1 cP; low shrinkage-5.1%) and satisfy SFIL-R processing requirements (oxygen etch resistance-33 wt% silicon, photocurable) and was used to validate our models through profilometry and interferometry experiments. During spincoating, minimizing the spin speed generates more planar films; however, this increases the spin time. To rectify this problem, a two-stage spincoating process-a first step with high spin speeds to achieve the target thickness quickly and a second step with low spin speeds to improve planarization-was proposed and experimentally demonstrated. (c) 2008 Society of Photo-Optical Instrumentation Engineers.

The step-and-flash imprint lithography process requires the clean separation of a quartz template from a polymer, and the force required to create this separation must be minimized to prevent the generation of defects. Fluorinated surfactant additives to the imprint fluid address this problem by migrating to the template-polymer interface and forming a local layer with ideal properties for adhesive fracture. Tensile and four-point bend fracture experiments show that surfactants lower the modulus of the imprint polymer and decrease the fracture energy. The fracture energy is further decreased by using a nonreactive, liquid surfactant versus a surfactant that reacts with the polymer matrix. Angle-resolved X-ray photoelectron spectroscopy results indicate that surfactant migration is more effective with a fluorinated surface treatment compared to an untreated quartz surface. This result shows that the use of fluorinated surfactants must be accompanied by a surface treatment that produces a similar energy or polarity to induce migration and lower the adhesive strength.

The step and flash imprint lithography (SF-.(L) process requires the clean separation of a quartz template from a polymer imprint, and the force required to create this separation must be minimized to prevent the generation of defects. According to fracture mechanics principles, decreasing both the imprint polymer modulus and the interfacial fracture energy are beneficial for reducing the separation force. Adjusting the crosslinker concentration in the imprint formulation decreases the modulus but does not significantly impact the facture energy. On the other hand., fluorinated surfactant additives to the imprint fluid lower the modulus of the imprint polymer and decrease the fracture energy. The fracture energy is further decreased by using a nonreactive, liquid surfactant versus a surfactant that reacts with the polymer matrix. Angle-resolved X-ray photoelectron spectroscopy (XPS) results indicate that surfactant migration is more effective with a fluorinated surface treatment compared to an untreated quartz surface. This result shows that the use of fluorinated surfactants must be accompanied by a surface treatment that produces a similar energy or polarity to induce migration and lower the adhesive strength.

Step and flash imprint lithography (SFIL) is low cost, high resolution patterning process and has found its way into a multitude of front end of the line (FEOL) and back end of the line (BEOL) applications. SFIL-R, a reverse tone variant of SFIL, and imprintable dielectrics are examples of such applications, and both require the design of specialized, silicon-based materials. Polyhedral oligomeric silsesquioxane (POSS) liquids were modified through a dual functionalization strategy to introduce photosensitive acrylate and thermally curable benzocyclobutane (BCB) groups to the molecule. The optimal functional group ratio was observed to be 3:5 acrylate to BCB, and the result was an imprintable dielectric with good mechanical properties and minimal post-exposure shrinkage. Thermal gravimetric analysis (TGA) revealed good thermal stability with minimal mass loss under annealing conditions of 400°C for 2 hours. Si-14 was designed to be a non-volatile, etch-resistant planarization layer for SFIL-R application. A polydimethylsiloxane (PDMS) derivative was modified to introduce acrylate functional groups and side branching for photosensitivity and low viscosity, respectively. Characterization of the material showed ideal planarization characteristics - low volatility (0.77 Torr at 25°C), low viscosity (15.1 cP), and minimal post-exposure shrinkage (5.1%).