Branched polymers with tunable branching densities are prepared by TEMPO-mediated radical polymerization. Thus, styrene is copolymerized with 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO methacrylate) by using 2,2′-azobis(2-methylpropionitrile) (AIBN) as initiator at 125 ℃. The method is based on the use of TEMPO methacrylate as branching unit that possessing a nitroxyl stable radical moiety as propagation radical trap and a polymerizable methacrylate group. Depending on the concentration of TEMPO methacrylate and polymerization time, hyperbranched polymers with different branching densities are obtained.
Reliability of a laser-via formation process for Fan-Out Wafer Level Packaging (FOWLP) technology was evaluated using Minimal Fab (MF) that is cleanroom-less and uses a half inch wafer. After a die-bonding and a compression molding process of a half-inch Si wafer, the laser-vias were formed with a diameter of 150 μm by irradiation of an ultra-violet (UV) pulsed laser beam. The measured thickness of the epoxy mold compound (EMC) was 93.9 μm of average with 1.9% of the variation at 1 σ in the half-inch wafer. The bottom diameter of the vias was 51.8 μm and 9.0% of the variation at 1 σ. In order to evaluate the contact-resistance of the vias, Cross-Bridge Kelvin Resistor (CBKR) test-structures were fabricated by the die-bonding the Si wafer with Al or Cu/Ti pads to a 42 alloy substrate, the compression molding, the laser-via, and the redistribution layer (RDL) formation. In case of the Al pads, the via conduction was obtained only in the outer peripheral area. On the other hand, in case of the Cu/Ti pad, the all via conductions were obtained. The high-yield via-interconnections were achieved by using Cu/Ti pads.
A type of reactive phosphorus based flame retardant, hydroxy(4-hydroxyphenyl)methyl)diphenylphosphine oxide (DPO-H), was synthesized and characterized by Fourier Transform Infrared (FTIR) and Nuclear Magnetic Resonance (NMR) spectroscopies. 4,4′-Diaminodiphenylsulfone (DDS) was used as the curing agent and DPO-H was used as the reactive flame retardant and co-curing to prepare the flame-retardant epoxy resins with different P contents. It can be observed that the introduction of DPO-H could enhance the transparency of epoxy resin. Flame-retardant epoxy resin samples were investigated by limit oxygen index (LOI) test, vertical burning (UL-94) testing, cone calorimetry test and thermogravimetric analysis (TGA). The results indicated that DPO-H can increase the flame retardation and carbon formation of epoxy resin. The flame-retardant epoxy resin sample with P content of 0.5 wt% can reach UL-94 V-0 rate, and LOI value increased to 29.6%. The flame-retardant mechanism of the DPO-H modified flame-retardant epoxy resin was analyzed by thermogravimetry-infrared combination (TG-IR), pyrolysis gas chromatography mass spectrum (PY/GC-MS) and scanning electron microscope (SEM). The results showed that the introduction of DPO-H can inhibit the pyrolysis of epoxy resin effectively. Epoxy resin modified by DPO-H had evident flame-retardant effect both in gas phase and condensation phase.
Linewidth Roughness (LWR) remains a difficult challenge for improvement in all resist materials. In previous work we focused on the impact of key components of LWR by analyzing the Power Spectral Density (PSD) curves which can be obtained using Fractilia’s MetroLER computational software. By measuring the unbiased PSD (with SEM image noise removed), accurate assessment of PSD(0) (the low-frequency limit of the PSD) and correlation length (the length scale of the transition from white to correlated noise) is possible. We showed there was an important relationship between ArF resist frequency components and LWR through lithographic process (before and after a resist trim step) as a function of resist formulation. In this paper we will study how key frequency components such as PSD(0) and correlation length change as we vary basic resist properties such as photoacid diffusion. The impact of aerial image on LWR and its frequency components will also be studied with particular attention to how correlation length affects LWR as feature size decreases. We will also look at the impact of photoacid diffusion or resist blur on PSD(0) as a function of aerial image Normalized Image Log-Slope (NILS). Understanding the relationship between PSD(0) and correlation length and how to manipulate these variables to minimize LWR for different features is crucial for more rapid LWR improvement at different nodes.
Application of a polyimide porous membrane having a three dimensional homogeneous structure to a photopolymer filter for semiconductors was examined. When polymer solution was passed through the polyimide porous membrane, there was no change in the molecular weight of the nonpolar polystyrene, but the high molecular weight molecules of the polar ArF model photopolymer T001 were selectively removed. Smaller pores and greater specific surface area in the polyimide porous membrane improve the adsorption efficiency, and the high molecular weight polar polymer removal property was promoted. Filtering photopolymers with the polyimide porous membrane suppressed the increase in defects that occurs with aging.
1-(2-Naphthyl)-2-(1-pyrrolidinyl)ethanone (MPY) was synthesized as a photoinitiator for free radical polymerization and the structure was characterized by spectral analysis. MPY has ability to initiate the polymerization of methyl methacrylate (MMA) monomer in air upon irradiation. Absorption and fluorescence properties of this initiator are investigated and the singlet excited-state energy value calculated in dichloromethane. According to the results, MPY acts as a type 2 photoinitiator.
This contribution summarizes advanced lithographic methods for polymeric 3D topographies based on the modification of the polymer molecular weight and applying thermal polymer reflow. Initial structures realized with grayscale electron beam and multi-photon lithography were reshaped due to thermal annealing close to the glass transition temperature following high-energy radiation. This allowed for new topographical functionalities such as aspheric and ultra-smooth freeform micro and nano-optics. The covered methods have in common that they exploit a specific contrast in molecular weight that enables post-processing and thus a transformation of the initial pattern by polymer reflow into a new surface topography or shape. Also, simulation methods are quickly summarized.
We examined the synthesis and resist properties of tellurium-containing molecular resist materials. By the condensation reaction of anisol, phenol, and 2-phenylphenol with tellurium tetrachloride (TeCl4), dichloro di(4-hydroxyphenyl) telluride (CHPT), dichloro di(4-hydroxy-3-phenylbenz) telluride (CHBT), di(4-hydroxyphenyl) telluride (HPT), and di(4-hydoxy-3-phenylbenz) telluride (HBT) were synthesized. These were reacted with 2-methyl-2-adamantyl bromo acetate, yielding corresponding compounds CHPT-AD, CHBT-AD, HPT-AD, and HBT-AD, respectively. By the examination of resist properties (thickness loss property, resist sensitivity, and etching durability), CHBT-AD could be good candidate for higher resolution EUV resist material.
Owing to the paradigm shift in energy systems from petroleum to electricity to realize sustainable society, the development of high-performance electrical devices has become increasingly important. The development of insulating materials with thermal stability and facile electrodeposition is essential for the production of high-performance next-generation electric devices because such electric devices cannot be coated with a conventional dip coating method. There are few reports on the development of polyimides with electrodeposition ability. Thus, we have reported that anionic electrodeposition coating was successfully performed using poly(amide acid) (PAA) nanoparticles that can be converted to polyimides (PI) upon thermal annealing. A hybrid coating using polyimide/bentonite with an inorganic filler was also produced, and the resulting electrodeposition films were thermostable at temperatures higher than 450 ℃. However, PAAs are usually subjected to hydrolysis, and so their pot life is not long. In this study, we developed cationic electrodeposition materials with solvent-soluble PIs with pendant epoxy groups. The developed materials served as good insulation coatings on substrates and exhibited excellent thermostability.
The directed self-assembly (DSA) behavior of block copolymers (BCPs) has recently been widely studied because of its potential application to the nanofabrication of semi-conductors. In this study, a novel molecular design based on the A-B-C triblock copolymer was developed: polystyrene-b-poly(dimethyl siloxane)-b-poly(substituted siloxane) (PS-b-PDMS-b-PMSCXOH, where X = 3 or 6). The high χ parameter between the PS and PDMS segments was expected to effectively reduce line edge roughness (LER) and resulted in a smooth interface with a lamellar nanostructure. The high etching resistance of Si-containing blocks also facilitates the potential pattern transfer to Si substrate. Small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) were used to reveal the self-assembly morphologies of A-B-C triblock copolymers, which are more complex compared to commonly studied binary system of A-B diblock copolymer. The reduced interface roughness in the microphase-separated nanostructures that can lead to reducing LER of patterns observed in bulk.
Cinnamoyl-modified methacrylate, 2-cinnamoyloxyethyl methacrylate (CEMA), was synthesized from 2-hydroxyethyl methacrylate (HEMA) and cinnamoyl chloride. Copolymers with various cinnamoyl contents were synthesized by random copolymerization of HEMA and CEMA at different feed ratios. Thus three copolymers with different CEMA contents were synthesized, and the monomer composition ([HEMA]:[CEMA]) in the copolymers ranged from 75:25 to 0:100. The coating films of copolymers on glass plates were prepared by the dip-coating method. Photo-induced dimerization of the cinnamoyl groups in the copolymers was confirmed by the ultraviolet-visible (UV-Vis) spectral changes. The cell proliferation on the photocrosslinked copolymers was tested using 3T3 Swiss albino mouse embryo fibroblasts. The results of the cell proliferation assay revealed that the photocrosslinked copolymers carrying more cinnamoyl groups promoted the cell proliferation compared with the photocrosslinked copolymers carrying less cinnamoyl groups. According to the results in the present study and our previous studies on cinnamoyl-modified trehalose and cinnamoyl-modified hydroxypropyl cellulose, it is presumable that the photodimerized cinnamoyl groups existing on the surface of materials at high density have some preferable effect on promoting fibroblast cell adhesion.