This paper describes discrete metal compounds that are soluble in commonly known ester and alcohol organic solvents such as PGMEA and PGME. These metal-containing compositions (RX4) can form homogeneous films in varying film thickness in the range of nanometers to micrometers with excellent film thickness uniformity of less than 300 Å. RX4 films are photosensitive and can form negative tone patterns under multiple exposure conditions. RX4 films demonstrate tunable optical and electrical properties. Furthermore, such films act as useful patternable hard mask due to their excellent etch selectivity against organic layers and silicon oxide. High density of RX4 films renders them exceptionally resistant to high power ion beams in applications involving ion implantation.
In the present study, photo-curing of polypyrrole decorated graphene oxide nanoparticle (PPy-GO) filled SU-8 photoresist and its effect on the electrical and mechanical properties of nanocomposite were investigated at different loading level of PPy-GO. Chemical structure of SU-8 and its nanocomposites before and after UV irradiation have been characterized using infrared spectroscopy. A significant increase of electrical conductivity was observed as a function of filler content in the nanocomposites confirming the conducting nature of the polymeric coating with incorporation of PPy-GOs. The real permittivity was observed to increase with increasing the PPy-GOs nanofiller loading, and the enhanced permittivity was interpreted by the interfacial polarization. The mechanical properties analysis demonstrated that the hardness has increased 2 time and SEM observations indicated well dispersion of PPy-GO nanoparticles within the cured SU-8 resin matrix.
Directed Self-Assembly (DSA) is one of the candidates for scaling feature sizes beyond 10 nm node. DSA has shown the capability for pitch reduction, contact hole (CH) shrinks and improvement in pattern profile and pattern collapse margin. Defectivity is one of the critical criteria for implementation of DSA as a technically viable approach. However, only few defectivity studies of DSA shrink in various topography have been reported. In this paper, we investigated wafer-level defectivity of DSA shrink at various stages of the DSA patterning process. The contribution from each process step and materials are partitioned and categorized. The DSA defectivity was reduced by optimizing the material quality, surface treatment and pattern transfer processes. Systematic defect sources over the wafer map have been reduced. Finally, an outlook as to the guidelines and challenges to DSA CH shrinkage process will be discussed.
The problem of stochastics in photoresist patterning is gaining increased attention. Understanding this problem requires new modeling methods. Here we describe the use of the Multivariate Poisson Propagation Model (MPPM) to study the relative importance of a variety of stochastic terms in both chemically amplified and non-chemically amplified resists. The results show that for the chemically amplified case, materials stochastic effects are on par with photon stochastics effects. The model is used to study both line-width roughness (LWR) impacts as well as contact size variations (CDU). As one might expect, contact CDU follows the same trends as LWR, but places even more sever constraints on the stochastic terms when considering the same feature size. Noting the contact patterning challenge, we also describe a phase-shift mask patterning method enabling the photon effect to be greatly reduced. At equivalent CDU, we demonstrate an effective 7x reduction in required source dose when patterning 25-nm half pitch contacts.
Nanostructured polypyrrole (PPy) was successfully prepared via template-free emulsion polymerization method. In this paper, we discuss the influence of polymerization conditions such as the types of doping agent, the reaction time, the reaction temperature, the types of oxidant, and the oxidant-pyrrole molar ratio on the yield and resistance of doped PPy. The results revealed that these factors had an important effect on yield and resistance properties of the doped PPy. When synthesized under the optimal reaction condition at 0 oC, the yield and resistance of the doped PPy were 66% and 0.12 Ω, respectively. In addition, the crystallinity, chemical structure and morphology of the doped nanostructured PPy under the optimal polymerization condition and the undoped PPy were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscope. The results demonstrated that doped polypyrrole has the morphology of interconnected spherical structure and higher crystallinity.
The suppression of line width roughness (LWR) is the most difficult task in the development of resist materials used for sub-10 nm fabrication. We have investigated the feasibility of the fabrication of line-and-space patterns with 7 nm quarter-pitch (7 nm space width and 28 nm pitch) with a chemically amplified resist process, assuming electron beam (EB) lithography. In this study, we investigated the requirement for suppressing LWR to 10 and 20% critical dimension (CD), using the simulation on the basis of the reaction mechanisms of chemically amplified EB resists. The simulation results suggested that the suppression of LWR to 20% CD is feasible, while 10% CD LWR is away from the current status of chemically amplified resists.
The TMAH developer (2.38 wt% aqueous solution) intrusion into a resist film is analyzed by the typical current-voltage (C-V) method. As well known device structure, Metal / Insulator / Semiconductor (MIS) structure is employed, and a resist film (novolak resin base) is adopted to an insulator material. During the TMAH developer dropping on the Au mesh electrode, an increase of the capacitance and a parallel shift towards a negative gate bias voltage region in a C-V curve can be clearly observed. At the first stage of dropping, these signal changes in C-V curve are relatively large. Refractive index of the resist film slightly increases after the TMAH developer dropping, which reflects the condensation of polymer resin due to the TMAH developer intrusion. A contact angle decrease of the TMAH developer after dropping is also monitored. A spreading coefficient cS of TMAH developer decreases gradually as the time elapse. Particularly, the capacitance change clearly indicates the intrusion of the TMAH developer as the function of a time elapses. These dynamic measurements of the intrusion will be effective to analyze the liquid intrusion mechanisms into polymer materials.
Photodynamic therapy (PDT) has drawn wide attention in intensive preclinical and clinical cancer therapy due to its noninvasive nature. A simple and facile synthesis of highly efficient delivery system for photosensitizers (PS) with visualized tumor environment is hence critical. Herein, a simple, safe and promising fluorescent probe, star-shaped poly(glutamic acid) with a porphyrin core (SPPLGA) was synthesized via ring-opening polymerization of β-benzyl-L-glutamate N-carboxyanhydride monomer with 5, 10, 15, 20-tetrakis-(4-aminophenyl)-21H, 23H-porphyrine (TAPP) as the initator, followed by the deprotection of benzyl groups on poly(benzyl-L-glutamate). The structure of this novel polymer was thoroughly studied by Nuclear magnetic resonance spectroscopy(NMR), Gel permeation chromatography (GPC) and Fourier transform infrared spectroscopy (FT-IR). Such star-shaped poly(glutamic acid) with porphyrin core could self-assemble into micelles in aqueous solution and exhibit pH-sensitive critical micelleconcentration. It was observed that with the decrease in pH, the fluorescence intensity of the SPPLGA increased. On the other hand, the incorporation of poly(glutamic acid) not only improved solubility of porphyrin in water, but also enhanced the production efficiency of the singlet oxygen (about double that of porphyrin). Those results suggest that these polymer, as promising pH-responsive and tumor-selective photosensitizers, are very promising for PDT and can potentially be used as ″theranostics″ for future cancer prognosis and therapeutic planning.
V- and T-shaped junctions of microchannel were formed by photolithography. It is clarified that the sub-pattern is effective to control the liquid flow in the channel junction by ESEM observation. These results will contribute to smooth flow at the channel junction in avoid of some trapping factors such as bubble formation.
Roll-to-roll UV nanoimprint lithography (R2RUVNIL) is a promising technology for fabricating nanostructures on flexible films, but its application requires finding feasible operating conditions to peel-off the UV resin from the mold. Furthermore, to achieve the required nanostructure, conversion of the UV resin needs to be precisely optimized in terms of the UV intensity and line speed. In this study, (1,6-bis(acryloyloxy)hexane) resin was cured by roll-to-roll UV-curing while monitoring its conversion and surface elasticity by Fourier transform infrared spectroscopy and a nano indenter, respectively. It was found that the conversion increases by up to 85% with a decrease in line speed and increase in UV intensity. The effect of varying the distribution of UV light on the roller mold was also investigated, which revealed that a sharp distribution of UV light is effective in increasing the surface elastic modulus from 0.2 to 1.0 GPa at 0.6 conversion.
Biocompatible photocrosslinked poly(vinyl alcohol) nanofibrous Scaffolds were successfully prepared by electrospinning and consequent photopolymerization. The nanofibrous membranes were subjected to detailed analysis by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). SEM images showed that morphology and diameter of the nanofibers were mainly affected by degree of substitute of metharyloyl group. XRD and DSC demonstrated form of a larger fraction of amorphous phase due to destroyed hydrogen bonding through methacrylation. Water stability test showed that the nanofibrous membranes improved its water stability with crosslinking degree increased. The indirect cytotoxicity assessments of the nanofibers were studied. And the result indicated the nanofibers was nontoxic to the L929 cells. This novel electrospun matrix would be used as potential wound dressing for skin regeneration.
This paper describes the invention of the molded mask method in the 1970s, which is considered to be the origin of current nanoimprint lithography. The molded mask method was proposed and developed in order to fabricate fine patterns and three-dimensional structures by combining molding technology and dry etching technology. The concept was the same as the technology now called nanoimprint lithography. In the 1970s, we had the idea that even very fine patterns (as small as ten nanometers across) could be fabricated by the molded mask method based on the similarity of this approach with specimen preparation for electron microscopy. How the molding mask method was born, the results of demonstration experiments, and studies conducted in the 1970s to solve technical problems are described in this paper. Recent progress in and applications of current nanoimprint lithography are also discussed with reference to the molded mask method.