| POLYMERS Vol.67 No.9 |
| >> Japanese | >> English |
COVER STORY
Polymers Support Electronic Devices |
| COVER STORY: Highlight Reviews |
| Toward Realization of Next-Genration Patterning with Directed Self-Assembly | Kenji YOSHIMOTO |
| <Abstract> In order to manufacture even more compact and powerful electronic devices, new technology that enables to build semiconductor integrated circuits with the minimum half pitch of 10 nm or less is required in the near future. Primary candidates for next-generation patterning technology include extremely ultraviolet lithography, nanoimprint, multi e-beam, and directed self-assembly (DSA). In this report, we briefly introduce DSA and explain the prospect for practical applications. DSA utilizes the microphase separation of block copolymers as a template for microfabrication. The period of the phase-separated domains is ～25-30 nm for the commonly used, lamella-forming PS-b-PMMA, which is far beyond the resolution limit of the state-of-art immersion lithography (～80 nm). The placement and orientation of the phase-separated domains is controlled by the pre-patterned surface, which is referred to as guide. One of the remaining challenges is the reduction of defects asscociated with the self-assembled structure. Due to a large number of parameters that may affect the defect formation, simulation is an effective tool for exploring the optimal conditions to suppress the defect level. By facilitating the development of new DSA materials (e.g., high-χ) and processes with the use of computer simulations, it is expected that DSA be a viable option for sub-10 nm patterning. Keywords: Directed Self-Assembly / Lithography / Micro/Nano Fabrication / Block Copolymer |
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| Simulation of Polymer Resist Film | Hiromasa YAGYU |
| <Abstract> A photolithography step consisting of coating of polymer resist, exposure and development is utilized for producing a nano-micropattern in a manufacturing process of electronics and MEMS (Micro Electro Mechanical Systems). A polymer resist film as the basis in the photolithography step, is selectively used according to its applications and degree of fineness. Process optimization and high precision patterning in photolithography requires a simulation technique because the process parameters such as molecular structure of resist, exposure and development step sensitively influence the produced pattern. There is two type of simulation methods, numerical analysis and molecular dynamics, and the appropriate method is used depending on the analysis scale. Several attempts of newly developed coarse-grained molecular dynamics models for chemically-amplified resist by the author are described together with recent progress in the simulation of polymer resist in this review. Keywords: Photolithography / MEMS / Molecular Dynamics / Photoresist / Exposure / Development |
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| COVER STORY: Topics and Products |
| Flexible Print Cable of Porous Polyimide Film | Kentaro TAKI |
| <Abstract> Porous polyimide film is a promising substrate for high-frequency data transmission owing to its low dielectric constant and low attenuation of signal. This paper reviews a series of studies about the production of porous polyimide film and subsequent attempts of production of flexible print cables. The porous polyimide film was created by newly developed zwitterion-induced phase separation of tertiary amine methacrylate and high-pressure CO2 and subsequent UV-induced photopolymerization. This process forms uniform porous structures and is applied to create the flexible print cables. Keywords: Porous Polyimide / Flexible Print Cable |
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| Evaluation and Analysis of Resin Shrinkage for PKG Substrate Warpage | Shinichiro ABE |
| <Abstract> Market of portable device has been growing. With the miniaturizing of mobile device as smart-phones and tablet PCs, semiconductor packages are demanded to be thinner and higher in density. However, thinner PKG tends to warp at the assembly process and cause the decrease in the connection reliability. Therefore core materials with low CTE(coefficient of thermal expansion) and high elastic modulus have been needed as a key solution for the reduction of the warpage for thinner PKG. We have newly developed core materials by reducing the resin shrinkage. In this paper, we reported analyzing the shrinkage mechanism and resin design. Keywords: Package / Shrinkage / Warpage / Simulation / Solubility |
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| LCD and Alignment Film | Fumitaka SUGIYAMA, Junji YOSHIZAWA |
| <Abstract> Liquid crystal displays (LCD) are used in TV, mobile device, PC, and etc. Many kind of polymer materials are used in LCDs. An alignment film that controls the direction of the liquid crystal (LC) is an essential material for high resolution, high transmittance, and low power consumption. A variety of properties such as anchoring the energy of the LC, inducement of the LC pretilt angle, voltage holding ratio, heat resistance, formation of thin film, and etc. are required in the alignment film. LCDs were, originally, commercialized with Twisted Nematic (TN) mode that fabric roll rubbs surface of alignment film to realize homogeneos alignment. As a second generation, in-plane switching (IPS) mode and vertical alignment (VA) mode are comercialized to overcome narrow viewing angle of TN mode. However, higher transmittance is still required for high quality LCDs. Photo alignment is a new technique for high transmittance to enable alignment of LCs by polarized ultra-violet (UV) exposure, and has been widely applied in both IPS and VA mode. Keywords: Liquid Crystal / Display / Alignment Film / Polyimide / Photo Reaction |
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| Mold Release Films of Semiconductors | Seigo KOTERA, Takatoshi YAOITA |
| <Abstract> We introduce encapsulating technique using mold release films for semiconductor devices which grow more than ever in the IoT era. Methods of the encapsulation by epoxy molding compounds (EMC) are divided into two main types, such as transfer and compression moldings. Taking advantage of its low-stress process, the compression molding plays a key role especially in memory market. Release films must combine easy release from the molded EMC and adequate flexibility to follow the shape of the mold. Ethylene-tetrafluoroethylene (ETFE) copolymer film is a best example which is able to satisfy both of above requirements even at high temperature. Typical data of those properties between ETFE and polyester films are shortly presented. Keywords: Release Film / Encapsulation / Molding / Semiconductor / Epoxy Molding Compounds (EMC) / Ethylene-Tetrafluoroethylene (ETFE) |
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| Polymer Science and I: A Personal Account |
| New Discoveries in Existing Fields | Takashi MORIOKA |
| <Abstract> This short essay describes what I am keeping in mind about research from the experience, and the reason I became a researcher. We cannot always explore new fields of research. Even in known fields, I believe that new discoveries are possible, and I will be working on such research. |
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| Front-Line Polymer Science |
| Control of the Crystalline Structure of Poly(vinilydene fluoride) (PVDF) | Hideo HORIBE |
| <Abstract> We obtained PVDF (form Ⅰ) by heat treatment at 185 and 190℃ after blending PVDF/PMMA 70/30 wt%(F70). The samples produced under other heat treatment and blend ratio conditions indicated PVDF (form Ⅱ). Results of DSC, polarized light micrography and light transmittance indicated that F70 heat-treated at 185 and 190℃ exhibited high compatibility between PVDF and PMMA. In contrast, PVDF (form Ⅱ) samples obtained in other conditions indicated lower compatibility. The PVDF crystalline structure of the original starting material changed into the structure of the PVDF (form Ⅰ) according to decrease of the crystallization rate by the highest compatibility. We quantified the solvent evaporation rate in the production of three PVDF crystalline structures using the solvent casting method. The results indicated that the crystalline structures of forms Ⅰ, Ⅱ and Ⅲ of PVDF were obtained when the solvent evaporation rates were <0.0001, >0.28 and between 0.02 and 0.03 g/min, respectively. It was established that the crystalline structure of PVDF from solvent casting is predominantly determined by the solvent evaporation rate. Keywords: Crystalline Structure of PVDF / PVDF/PMMA / Compatibility / Heat Treatment / Residual Solvent / Dipole Moment Solvent / Solvent Evaporation Rate |
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