Hitachi Chemical DuPont MicroSystems (HDMS) is a supplier of photosensitive negative-tone polyimides (PI) and positive-tone poly(benzoxazole)s (PBO) for use as protection layers in semiconductor ICs or as dielectrics for re-distribution layers in Fan-in or Fan-out wafer level packages. These materials offer an easy manufacturing process as well as ensuring high reliability in semiconductor packages. Recently, design rules and structures for next generation packages are advancing in order to achieve higher end multi-functionality. In accordance with this trend, next generation PIs and PBOs need to be developed to address new challenges that include lithographic properties, in-process compatibility and end-use properties and, in this paper, the latest material sets developed by HDMS will be introduced for advanced packaging applications. The 1^st material set is a low stress photosensitive PI designed especially as a protection layer in advanced process node semiconductor ICs where warpage reduction and better protection capability for fragile low-k layers are needed. The 2^nd and 3^rd material sets are designed as low temperature curable photosensitive PI and PBO for use as dielectrics in Fan-out wafer level package to provide good applicability with future device designs as well as high package reliability by improving resolution, cured film properties, adhesion, insulation reliability, and others.

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The soluble polyimides were synthesized from tetracarboxylic dianhydrides such as 3,4'-oxydiphthalic anhydride (3,4’-ODPA) and diamine monomers having various photoreactive groups, which are photo-oxidative groups, photoreaction groups based on photoresist technology, and photochromic groups. The thin films of obtained polyimides were irradiated by UV light (λ max; 254 nm or 365 nm), and the contact angles for the water decreased from near 100° (hydrophobicity) to minimum 20° (hydrophilicity) in proportion to irradiated UV light energy. The reversible wettability changes of the polyimides having photochromic groups by UV-Vis light irradiation were also investigated. Various surface analysis such as ATR, solid state refractive UV, XPS support above surface wettability changes of the polyimides.

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Laser based direct write exposure tool for advanced semiconductor packaging has been introduced into the market. The tool has unique features compared to existing high-pressure mercury lamp based exposure tools. The tool does not require any masks or reticles because it equips with state-of-the-art light valve called Grating Light Valve (GLV) along with high power laser unit producing wavelength of 355 nm. Minimum resolution that the tool is able to draw is 2μm lines/spaces with overlay accuracy of equal to or less than 1 μm at average plus 3σ, that satisfies most advanced packaging requirement as of today. In the paper, we will introduce the advantage of this type of exposure tool in the market and discuss about technical challenges.

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Photodeprotection of N-octyloxybenzyl aromatic polyamide film containing photo acid generator (PAG) was investigated. The photodeprotection was proceeded well under UV irradiation (5 J/cm²), followed by heating at 130 °C for 15 min in the presence of 25 wt% of PAG. Line pattern of 30 to 20 μm on Si wafer was obtained from the photosensitive film after dipping into acetone. It turned out that N-alkoxybenzyl aromatic polyamides serve as a new photosensitive material in the presence of PAG.

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Porous polyimide film is a promising substrate for high-frequency data transmission owing to its low dielectric constant and low attenuation of signal. In this study, lateral patterning of porous polyimide, consisting of porous and non-porous areas, was performed selectively using a photomask via a two-step UV irradiation method. The first UV irradiation polymerized the tertiary amine monomer that participates in the selective formation of pores with the photomask. The second UV irradiation was administered after the product was exposed to high-pressure CO₂. The porous structure was observed over the masked area; none or few pores existed over the exposed area. The optimal lateral pattern rate of the porous structure is 21% with an expansion ratio of 1.26 corresponding to porosity. Moreover, the mean diameter of isolated pores was measured at 2.7 μm. The technique used is a promising approach to draw electrical circuits arbitrarily while retaining the mechanical strength and electrical insulation.

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Ordering and orientation of high-molecular-weight (HMW) block copolymer (BCP) are challenging issues for recent technology to push the limit of nanoscopic size to hundreds-of-nanometers scale. HMW polystyrene-b-poly(methyl methacrylate)s (PS-b-PMMAs) were used to actualize larger feature sizes of giant lamellar and gyroid (GYR) nanostructures. The solvent vapor annealing (SVA) process was exploited to develop the long-range order nanostructures in the HMW BCP films. Directed orientation of nanostructures and the defect annihilation are discussed in terms of the interfacial interactions on the substrates and topographic trenches to design well-defined regular nanopatterns.

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DSA lithography is a chemical assisted patterning approach, which has attracted a great deal of interest due to its potential high resolution and low cost. Researchers around the world discovered some sub-5 nm high resolution DSA materials, and all these materials required high annealing temperature or long annealing time. In this study, we design and synthesize some PS-typed and PMMA-typed fluoro-containing BCPs. The finest half pitch of these BCPs is less than 5 nm. And the thermal annealing time of PS-typed BCPs is optimized to 1 min, which has been the highest assembly speed for sub-5 nm nanopatterning. The self-assembly speed of PMMA-typed BCPs is much slower than the PS-typed. We further exhibit that ordered nanopatterns are assembled to appear straight 10 nm lines in the silicon template.

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The curing behavior of the type II photoinitiator package based on different weight ratios of o-Cl-HABI (hydrogen acceptor)/NPG (hydrogen donor) systems (where o-Cl-HABI is a 2-chlorohexaaryl biimidazole, NPG is an N-phenylglycine) was investigated through FT-IR, gel-fraction, electron spin resonance (ESR) and photoluminescence (PL) methodologies. As the amount of NPG increasing, the faster curing speed occurred. However, the curvature photo-reactivity phenomenon was observed as the amount of o-Cl-HABI at 0.5, 1 and 2 wt%, respectively. In addition, the radical transfer mechanism in the presence of air and nitrogen atmospheres was also discussed in this study.

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Most of the photosensitive materials are based on photoradical and/or photocationic polymerization, because many photoradical and photoacid generators, monomers, and oligomers are commercially available. Although photosensitive materials based on base-catalyzed reactions have merit in preventing erosion of metallic substrates, Photobase generators (PBGs) generally have lower quantum yields when compared to photoradical initiators (PIs) and photoacid generators (PAGs). We report here novel PBGs based on a benzoin structure. This PBG can liberate radicals as well as bases with high efficiency by i-line irradiation, so that a homogeneous organic-inorganic hybrid film can be formed. As a result, the hardcoating materials based on the organic-inorganic hybrid show high pencil-hardness (4H), transparency, and scratch resistance compared to coating materials using conventional PIs and PBGs.

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Radical UV curable resin commonly shrinks during photopolymerization, which is difficult to avoid. This study developed an apparatus to measure the degree of shrinkage under nitrogen and air atmospheres. The apparatus consisted of a laser displacement sensor to detect the height of the spun-cast resin on a sapphire plate, two fused silica windows, a nitrogen purging line, and a UV light source. The initial and final thickness of a mixture of diurethane dimethacrylate/1-hydroxycyclohexyl phenyl ketone showed a linear relationship between 50 and 140 μm. The linear relationship was used to calculate the degree of shrinkage assuming an initial film thickness of 80 μm. The degree of shrinkage in nitrogen atmosphere was 1.3% greater than that in air. The relationship between the degree of shrinkage and UV intensity in the nitrogen atmosphere exhibited a single linear relation, while that in air showed two lines. UV intensities lower than 15 mW/cm² exerted a more significant influence on the degree of shrinkage.

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We have developed the crosslinked films of diphenyl- or dinaphthylfluorene having acryl units with polymethylphenylsilane in the presence of a photoradical initiator upon irradiation at 405 nm with thermal treatments at around 100 ^oC. The photopolymerization of the acrylates effectively enhanced by the photo-thermal dual curing technique. Polysilane moieties were incorporated into the film by the termination reaction between the acrylate radicals and Si radicals generated by the slight photo-decomposition of the Si-Si bonds. We have successfully fabricated the films with high refractive indices (n_D: 1.62) and the refractive index values were tunable by irradiation at 254 nm by the effective decomposition of the Si-Si bonds of the polysilanes. The reaction mechanism is discussed based on real-time FT-IR measurements. The prepared films have a high thermal stability (temperature for 5% weight loss, T_d5: 300 ^oC).

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Photoremovability of cross-linked polyperoxides was investigated considering the application to dismantlable adhesives. Applying lap-shear stress on the glass joints bonded by the cross-linked polyperoxides, i.e., the alternating copolymer of 2-hydroxyethyl sorbate and oxygen cross-linked by tolylene 2,4-diisocyanate, resulted in the failure of the glass adherend. UV irradiation on the bonded glass joints more than 19 J/cm² resulted in a significant decrease in the lap-shear adhesion strength due to the photodegradation of the cross-linked polyperoxides, and the bonded glass joints were successfully debonded without breaking the glass adherends. The failure mode was the cohesive failure of the adhesive and the residue of the cross-linked polyperoxides heavily adhered on the both debonded glass adherends. The additional photoirradiation on the debonded glass adherends in tetrahydrofuran resulted in the significant removal of the adhered cross-linked polyperoxide due to the further photodegradation. After 150 J/cm² irradiation, the adhesive residues were completely wiped off from the glass adherends.

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Photo-induced polymerization and degradation processes provide drastic physical changes of monomeric and polymeric systems. Herein we demonstrate three multifunctional methacryloyloximes composed of core aromatic rings and photolabile O-acyloxime units, including newly prepared truxenone tris(O-methacryloyl)trioxime. These molecules afforded covalently crosslinked copolymers by free-radical polymerization. The methacryloyloximes also worked as photoinitiators that release free-radicals on irradiation with near UV light. Furthermore, resulting polymers degraded on irradiation due to the cleavage of covalent bonds. These results indicate that the methacryloyloximes played multiple roles in the formation and degradation of networked polymeric materials.

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In recent years, mechanical properties of flexible materials have attracted much attention for the development of stretchable electronic devices, flexible sensors and wearable biointegrated devices that would support the future ‘Internet of things’ (IoT) and ‘information technology’ (IT). For designing advanced soft devices, there is a strong demand to quantitatively analyze the deformation behavior of soft materials. Recently, a surface labeled grating method has been developed as a new tool to quantitatively measure the bending behavior of flexible films. In this study, we investigated the effect of hardness of the film to be measured on the surface strain evaluated by this method.

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A new star-shaped azobenzene chromophore was synthesized to form micrometer-sized spheres exhibiting stable photoswitching ability. The light-sensitive microspheres were prepared by the spherical assembly of the star-shaped azobenzene chromophores. UV-visible absorption spectroscopy and optical microscopy (OM) experiments were employed to investigate repeated light-induced molecular conformational changes of star-shaped azobenzene molecules in the microspheres and the resulting morphological stability. Photoswitching was repeated stably more than 14 times without any appreciable deterioration in the absorption spectra under repeated UV and visible light irradiation.

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There is an urgent need to develop new methods for assessing strain in polymers without damaging the material’s intrinsic properties. The disadvantages of current methods include: high costs; impregnation of the polymer with bulky mechanical devices; inability to measure in several dimensions; and interaction with electromagnetic radiation. In this paper, a method to detect strain in elastic polymers that is based on energy transfer between two fluorophores is presented. By incorporating donor and acceptor dyes in poly(dimethylsiloxane) (PDMS) and monitoring the change in emission spectral profile, evidence of strain is gathered. We first demonstrate the successful doping of the elastomer with the dyes fluorescein and rhodamine B by using different optical techniques. PDMS strips containing the two dyes are fabricated and their emission spectral profile upon stretching is analyzed using a spectrometer. As the strip is extended, the distance between donor and acceptor molecules increases, resulting in a decline in energy transfer efficiency. This is manifested by intensification of emission from fluorescein, accompanied by a decline in emission from rhodamine B. The effect of dye incorporation on the polymer’s elastic properties is explored with an extensometer. Next, strain in samples is visualized using a simple digital camera and basic image-processing methods. Finally, a gradual flexibility PDMS is manufactured and the nonuniform distribution of strain in it is charted.

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Thickness of 193 immersion photoresist (PR) has been continuously reduced to achieve smaller critical dimension (CD) beyond 1x nm nodes. As a result, faster etch rate (E/R) bottom antireflective coating (BARC) is required to maintain appropriate PR thickness as a mask for pattern transfer and small CD bias after dry etch process of BARC. The etch rate of BARC can be theoretically predicted by Ohnishi Parameter (O.P.); faster etch rate can be obtained by high O.P. with increase in number of hydrophilic heteroatoms, such as nitrogen (N) or oxygen (O). However, poor solubility of high polar resin is the major technical barrier in development of faster E/R BARC. We have designed novel polarity-switchable BARC (PS-BARC) with enhanced solubility via hydrophobic protecting groups while maintaining fast etch rate. In this paper, details of BARC new fast E/R immersion BARC for 193 nm lithography will be discussed.

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In the recent of the semiconductor manufacturing process, variety of properties (narrow gap-filling and planarity etc.) are required to organic BARC in addition to the conventional requirements. Moreover, SC-1 resistance is also needed because BARC is often used as a wet etching mask when TiN processing. But conventional BARC which include crosslinker does not have enough SC-1 resistance, and we found that it is also difficult to obtain good gap-filling and good planarity because of outgassing and film shrinkage derived from the crosslinker. In this study, we have developed the new self-crosslinking BARC. The new crosslinking system shows low outgassing and film shrinkage because of not including crosslinker. So, novel BARC has better gap filling property and planarity and over 3 times higher SC-1 resistance than that of conventional BARC. Moreover, by adding the low molecular weight additive which has high adhesive unit to TiN surface, the novel BARC has over 10 times higher SC-1 resistance than that of conventional BARC. And this novel BARC can be applied both ArF & KrF lithography process because of broad absorbance, high etching rate, chemical resistance (SC-1, SC-2, DHF, and others) and good film thickness uniformity. In this paper, we will discuss the detail of new self-crosslinking BARC in excellent total performance and our approach to achieve high chemical resistance.

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The contentious issue in ArF lithography is to reduce cost with multi-patterning process. To achieve low defectivity is required at high speed scanner for increasing throughput. Especially, demand of applying top-coat (TC) less process is being increasing recent year at using high speed scanner. The hydrophobic film surface is preferred because less immersion defect is caused without remaining water droplet in exposure. For positive-tone development (PTD) by using alkaline developer, the polarity-change property function of film surface from hydrophobic to hydrophilic after alkaline development process is key to reduce defectivity. High alkaline-responsive materials which were not only polymer additives but also copolymers as main component of resist have good potential to defectivity reducing. Additionally, to suppress swelling is one of very impotent factor to improve bridge type defect mode.

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In order to create a new stimuli-responsible emitting system, we have investigated the thermal phase behaviors and emitting properties of the film of 1-acetylaminopyrene (AAPy) dispersed in poly(vinyl acetate) (PVAc). By heating the amorphous film obtained by spin-coating method, crystallization took place at ca. 130 ^oC followed by melting and/or resolution to recover the homogeneous film over 200 ^oC. Both crystalline and amorphous phases could be reversibly obtained at room temperature by annealing the film at 130 ^oC and 245 ^oC, respectively. Such phase transition to control the state of the film at room temperature allowed the reversible fluorescence color change of the film due to the difference of emission spectra between amorphous and crystalline phases.

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In this communication, we report on the disappearance of reflection color by photopolymerization of an acrylate monomer in lyotropic cholesteric liquid crystals from a cellulose derivative for color image applications. When a hydroxypropyl cellulose (HPC) derivative possessing propionyl side chains (HPC-Pr) was homogeneously dissolved in a liquid monomer of 4-hydroxybutyl acrylate (4HBA), we obtained lyotropic cholesteric liquid crystals (HPC-Pr_4HBA) with a Bragg reflection peak in the visible wavelength range. Such reflection wavelength was controllable by not only temperature, but also concentration of HPC-Pr in 4HBA. We found that Bragg reflection peak of lyotropic HPC-Pr_4HBA mixture disappears by photopolymerization of 4HBA, thereby leading to the fabrication of a photolithographic color image. This report provides promising clues to fabricate intriguing photonic devices adopted with cellulose derivatives by utilizing such Bragg reflection characteristics.

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Fiber-oriented film was prepared by electrospinning method using polyvinyl alcohol with stylbazol quaternized group (PVA-SbQ), and the formation behavior of polyiodine complex in fibers was investigated. From the UV-vis spectra and the Raman spectra, it was revealed that PVA-I₅‾ was formed in the fiber orientated film after staining. It is presumed that in the fiber oriented film, the iodine complexes are aligned in one direction. It is considered that the polyiodine complex is inductively arranged with respect to the orientation of fibers, which contributes to the development of dichroism.

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During the nanoimprinting process, transfer failure is caused by the presence of air between mold and substrate or the gas generated from the resist material. Therefore, a gas permeable metal plate was prepared, and a plant-derived material containing 50 wt% acetone, was used as the imprinting mold. The gas permeability of the metal plate was evaluated. The results reveal that no gas pool comprising volatilized acetone was found on the surface of the mold material. Thus, the use of gas permeable metal plates can reduce the transfer defects occurring in imprint lithography.

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Lithography using siloxane polymers is reasonable for process reduction compared to mask etching process. Generally, crosslinkable groups, such as acrylates and epoxides, and protecting groups are added to siloxane polymers for lithography. We synthesized polydiphenylsilane without those functional groups, and the thermal behavior of that was observed with TG-DSC-MS. The thermal elimination of phenyl group from polydiphenylsilane was observed and the thermal weight loss until 500 °C was under 3%. The polysilane film was directly imaged with EB nano melting apparatus (ENF-3500) and line width of pattern was 12.9 μm. The film thicknesses before and after development were same. The partial heating by EB irradiation caused oxidation of polydiphenylsilane after elimination reaction of phenyl group and cleavage of Si-Si bond by XPS analysis.

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