2016 PST Awardees

The Outstanding Achievement Award

The Photopolymer Science and Technology Award No.161100

Takumi Ueno, Shinshu University

 

   The Photopolymer Science and Technology Award No.161100, the Outstanding Achievement Award 2016, was presented to Takumi Ueno (Shinshu University) for his outstanding achievements in photopolymer science and technology, “Development of new advanced photosensitive materials for microelectronics”.

   Takumi Ueno is Designated Professor for Shinshu University. He received Ph.D. (1979) degree in Chemistry from Tokyo Institute of Technology. He jointed Central Research Laboratories of Hitachi Limited in 1979, and began his career in resist materials for electron beam lithography and photolithography. He moved to Hitachi Research Laboratories of Hitachi Limited to start the research on photosensitive polyimides and package materials in 1995. He joined Hitachi Chemical Co. to research and develop photosensitive materials for microelectronics packaging and display in 2001. He joined for Hitachi Chemical DuPont Microsystems in 2003 to 2005 as a director of R&D. He is engaged both in the education for graduate students in university and industries at Shinshu University.

The Best Paper Award 2016

The Photopolymer Science and Technology Award 162100

Tatsuhiko Yajima1, Wenfeng Hai1, Tei Hi1, and Keita Shimizu1,

1. Saitama Institute of Technology

   The Photopolymer Science and Technology Award No. 162100, the Best Paper Award 2016, was presented to Tatsuhiko Yajima, Wenfeng Hai, Tei Hi and Keita Shimizu (Department of Applied Chemistry, Graduate School of Engineering, Saitama Institute of Technology) for their outstanding contribution published in Journal of Photopolymer Science and Technology, 28, (2015) 479-483, entitled “Preparation of a Super Hydrophilic Polytetrafluoroethylene Surface Using a Gaseous Ammonia-Water Low-Temperature Plasma”.

 

 

The Best Paper Award 2016

The Photopolymer Science and Technology Award 162200

Hiroki Takano1,  Lei Wang1,  Yuki Tanaka1,  Rina Maeda1,  Naoko Kihara2,  Yuriko Seino2,  Hironobu Sato2,  Yoshiaki Kawamonzen2,  Ken Miyagi2,  Shinya Minegishi2,  Tsukasa Azuma2,  Christopher K. Ober3, and Teruaki Hayakawa1,

1. Tokyo Institute of Technology, 2. EUVL Infrastructure Development Center, Inc, 3. Cornell University

   The Photopolymer Science and Technology Award No. 162200, the Best Paper Award 2016, was presented to Hiroki Takanoa,  Lei Wanga,  Yuki Tanakaa,  Rina Maedaa,  Naoko Kiharab,  Yuriko Seinob,  Hironobu Satob,  Yoshiaki Kawamonzenb,  Ken Miyagib,  Shinya Minegishib,  Tsukasa Azumab,  Christopher K. Oberc, and Teruaki Hayakawaa (1. Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2. EUVL Infrastructure Development Center, Inc, 3. Materials Science & Engineering, Cornell University) for their outstanding contribution published in Journal of Photopolymer Science and Technology, 28, (2015) 649-652, entitled “Vertical Oriented Lamellar Formation of Fluorine- and Silicon-containing Block Copolymers without Neutral Layers”.

 

 

Their achievements are described below.

The Outstanding Achievement Award

The Photopolymer Science and Technology Award No.161100

Takumi Ueno, Shinshu University

Prof. Takumi Ueno has been engaged in development of many resist materials and photosensitive polyimides for microelectronics and electronic package and contributed to the progress of photopolymer science and technology as described below.

 

1. In the 1979, at the time Dr. Ueno joined Central Research Labs of Hitachi Ltd., it had been recognized that there were controversial candidates for the next generation lithography of g-line reduction projection tool, such as multi-layer lithography especially two-layer resist system, dry development, contrast enhancement and i-line lithography, X-ray lithography and electron beam lithography, required by evolving integrated circuit designs. He and his colleagues have proposed several candidate materials for those lithography described below. He started with the resist of iodinated polystyrene for the direct writing electron beam techniques. Then Dr. Ueno and his colleagues started to apply non-swelling electron beam resists composed of combined with bisazide compounds and poly(hydoxystyrene) to electron beam resists.  This type of resists was developed by Dr. Iwayanagi as an alkali-developable non-swelling negative deep-UV resists.

2. He and his colleagues involved in development of two-layer resists, since the high resolution and high aspect-ratio patterns were demonstrated by three-layer resist system and there was strong demand for materials of simpler process compared to three-layer resist system. Dr. Ueno found the iodine compound show oxygen plasma resistance in the course of the study of oxygen plasma resistance for various polymers. This was attributed to the iodine oxide formation during oxygen plasma treatment which led to design the alkali-developable positive resists containing iodine phenol for two-layer resist system. They also proposed alkali-developable positive resists containing silicon containing resist (ASTRO) with high-resistance to oxygen RIE. For the contrast enhancement layer (CEL), he and his colleagues proposed the diazonium salts as photobleaching material. He and his colleagues analyzed the behavior of CEL during light exposure which led to proper material selection.

3. He and Prof. Bargon’s colleagues at Institute of Physical Chemistry of Bonn University proposed the patterning of conducting polymers during his stay there. He found the decrease in the conductivity of the

synthesized film when the prepared solution of FeCl3 was exposed to UV light in the course of the vapor phase synthesis of poly(pyrrole) on the poly(vinyl chloride) film with Fe(III)-salts. This is considered to be the direct patterning of the conducting polymers.

4. In late 1980s he and his collaborators started to develop the chemical amplification resist systems. Co-working with Dr. Hesp and Mr. Hayashi, they proposed the system composed of tetrahydropyranyl (THP) and furanyl protected poly(hydroxystyrene) with an acid generator. THP and furanyl groups are deprotected under acid catalyzed reaction and the exposed region increases the dissolution in alkali aqueous developer. This type of system had been extended to acetal type resist by Dr. Hattori. Dr. Ueno proposed a new type of acid generator of sulfonates. These acid generators show efficient acid generation capability. This high efficiency is attributed to the sensitization by phenolic resins under light exposure, which was clarified by the series of studies of reaction mechanism as well as the measurement of quantum yield of acid generation in film state. Dr. Schlegel and he also proposed the measurement method of acid diffusion length in chemical amplification resists using the resist dissolution of acid diffused region in alkali-aqueous developer. This type of method is now utilized for measurement of acid diffusion in general. His group also has proposed various positive and negative chemical amplification resist systems.

5. In late 1980’s and early 1990s, Central Research Labs of Hitachi Ltd. began a serious effort to develop i-line phase shift lithography. The phase shift lithography was one of the candidates for the next generation of i-line lithography before the KrF lithography was utilized. This effort led to the negative resists for phase-shift lithography composed of phenolic resin and azide compounds. The chemical amplified i-line negative resist systems were also proposed. These negative resists stimulated the progress of the development of the phase-shift lithography.

6. In early 1990s, his group focused on positive and negative electron beam resists utilizing chemical amplification systems for direct writing of electron beam lithography. The positive system composed of THP protected poly(vinylphenol) (THP-M) as dissolution inhibitor in novolak resin and an acid generator was proposed. Several acid catalyzed negative systems have been proposed. Dr. Uchino and Dr. Ueno proposed new base-labile compounds which induce a polarity-change from water repellant to hydrophilic compounds during aqueous base development. This unique approach led to the dramatic improvement in resolution.  

7. In middle 1990’s he joined Hitachi Research Laboratories of Hitachi Ltd. and started to develop photosensitive polyimide with his colleagues.

8. He moved to Research Center of Hitachi Chemical. Co. in 2001 and involved in R&D of the photosensitive materials for display and packaging of microelectronics. He joined Hitachi Chemical DuPont Microsystem Corporation as Director of R&D from 2002 to 2005. He oversaw the introduction of several new technology/product platforms including the positive poly(benzoxyazole) (PBO), low-temperature curable positive PBO and low coefficient of thermal expansion (CTE) photosensitive polyimides.

9. He also contributed the research and development of resist materials in writing review articles and books.

 

Prof. Takumi Ueno performed a pioneering work on advanced photosensitive materials for microelectronics. He has been devoting himself to the progress of photopolymer science and technology. He has published many publications and patents in the area of microlithography and microelectronic packaging. Furthermore, his important research results have been presented at the annual Conference of Photopolymer Science and Technology and his many papers have been published in Journal of Photopolymer Science and Technology. As described above, the photosensitive materials such as the resist materials and photosensitive polyimides with whose development he is most closely associated has been the mainstay of the photosensitive material industry for over 30 years. 

 

The Best Paper Award 2016

The Photopolymer Science and Technology Award 162100

Tatsuhiko Yajima1, Wenfeng Hai1, Tei Hi1, and Keita Shimizu1,

1. Saitama Institute of Technology

    Polytetrafluoroethylene (PTFE) is a material of great technological interest because of its low dielectric constant, high thermal stability, thermoplastic properties and chemical inertness. It is an excellent candidate for many applications, particularly in the microelectronics industry, but its chemical inertness make it difficult to adhere to other materials. Therefore, surface pretreatment is essentially needed before adhesion.
     Plasma treatment is widely used for such an object since plasma modifications can be achieved without changing bulk properties of materials. A number of studies concerning the plasma modification of surfaces of polymers have already been published. Recently the surface modification of PTFE by plasma treatment using a mixture of gases has attracted a great deal of attention. Argon and ammonia plasma was very efficient in modifying the PTFE surface.
     In the present article, the authors found the low-temperature plasma with a mixture of gases of argon, ammonia and water was very effective to super-hydrophilization on the inert surface of PTFE. Adding water vapor to an argon ammonia plasma or oppositely adding ammonia to an argon water plasma decreased the contact angle of PTFE dramatically and eventually they could turn superhydrophilic surfaces of PTFE films with the smaller contact angle than 4°.
     This study aimed to develop a new method for modifying the PTFE surface, making it more wettable, that is, lowering its contact angle and improving its mechanical property such as the peel strength through low-temperature radio-frequency (RF) plasma treatment.
     The authors conducted to modify PTFE specimens by RF inductively coupled plasma using various gases: oxygen (O2), oxygen with water vapor (O2/H2O), argon (Ar), argon with water vapor (Ar/H2O) and argon with ammonia and water vapor (Ar/NH3-H2O). The contact angle of the as-received PTFE film was 118°, while the surfaces modified by O2 and Ar plasmas exhibited 112 and 110° contact angles. It is conceivable that these slight decreases in the contact angle resulted from a decreased fluorine density at the surface due to fluorine elimination by plasma-activated species. The surface chemical properties thus appeared to change following treatment and become closer to those of graphite, which has a water drop contact angle of ca. 90°, because of the elimination of fluorine atoms from the PTFE surface by the O2 or Ar plasma. The addition of water vapor to those plasmas (the O2/H2O and Ar/H2O plasmas) had little effect in terms of lowering the contact angle. However, the addition of ammonia to the Ar/H2O plasma or the addition of water vapor to the Ar/NH3 plasma (the Ar/NH3-H2O plasma) significantly reduced the contact angle to give a super hydrophilic surface exhibiting contact angles of 4° or less using the Ar/NH3-H2O plasma with the following conditions: Ar flow rate = 63.9 cm3 min-1 SATP (2.61 mmol min-1); ammonia water reservoir temperature = 25 °C; NH3 flow rate = 0.43 mmol min-1; H2O flow rate = 0.04 mmol min-1; total gas pressure = ca. 80 Pa; rotation speed of reactor tube = 130 rpm; net RF power = 100 W; RF irradiation time = 15 min.
     Detail surface analyses by X-ray photoelectron spectroscopy and scanning electron microscopy, it was revealed that the fluorine elimination was occurred from PTFE surface contacting with Ar/NH3-H2O plasma and hydrophilic functional groups containing oxygen and nitrogen atoms such as OH and NH2, respectively, bonded to the PTFE film surface, and at the same time the surface morphology was dramatically changed to get an effective roughness.

    Improved wettability is desirable with regard to increasing the adhesive properties of a polymer surface. According to the Wenzel model which defines a rough surface adhering closely to liquid phase, the wetting properties of a material are determined by two factors, the surface energy and the surface roughness, and so wettability can be tuned by controlling these characteristics. In this study, they found that an Ar/NH3-H2O plasma can provide this tuning, simultaneously generating a hydrophilic chemical structure and effective morphological roughness on PTFE surfaces and thus readily changing the highly hydrophobic surface to super-hydrophilic. As described above, the authors have demonstrated comprehensive fundamental research on a methodology for preparing a superhydrophilic
surface of polymer material using PTFE. These important research results were presented at the Annual Conference of Photopolymer Science and Technology in 2015 and the paper was published in the Journal of photopolymer Science and Technology. These contributions also give the fundamental aspects to create surface functional polymer materials including surface conductive, biocompatible, and
so forth.

 

The Best Paper Award 2016

The Photopolymer Science and Technology Award 162200

Hiroki Takano1,  Lei Wang1,  Yuki Tanaka1,  Rina Maeda1,  Naoko Kihara2,  Yuriko Seino2,  Hironobu Sato2,  Yoshiaki Kawamonzen2,  Ken Miyagi2,  Shinya Minegishi2,  Tsukasa Azuma2,  Christopher K. Ober3, and Teruaki Hayakawa1,

1. Tokyo Institute of Technology, 2. EUVL Infrastructure Development Center, Inc, 3. Cornell University

    To keep up with the demands in the microelectronics industry for smaller devices with increased pattern densities, the ability to fabricate nanopatterns in the sub-10 nm scale beyond conventional optical/EUV lithography is vital. The self-assembled nanostructures of block copolymers (BCPs) hold the key for the development of next-generation nanolithography technologies, and particularly vertically oriented lamellar structures are crucial for the fabrication of high resolution line and space (L/S) patterns in microelectronic devices.
     BCP materials are essential for the fabrication of thin films with vertically oriented lamellar structures with sub-10 nm feature sizes. To realize vertically oriented lamellar structures by BCP materials, controlling the balance between the surface segregation and the thermodynamic incompatibility of the blocks is important. Strongly segregating BCPs tend to avoid forming vertically oriented lamellae as a result of the large difference in the surface free energies between the blocks, whereas highly incompatible blocks are necessary to achieve smaller feature sizes. In general, there is a trade-off between increased block incompatibility and an increased tendency for the formation of vertically oriented lamellae.

     Prof. Hayakawa, Dr. Maeda, Dr. Azuma, Prof. Ober and their groups proposed a novel class of fluorine- and silicon-containing BCPs as a solution to the above trade-off problems. Based on earlier work done by the group, in this paper, a series of poly(methacrylate polyhedral oligomeric silesequioxane)-blockpoly(trifluoroethyl methacrylate) (PMAPOSS-b-PTFEMA) BCPs with a silicon-containing PMAPOSS block and a fluorine-containing PTFEMA block (γPTFEMA = 2 5.1 m J m -2) were
developed for the fabrication of vertically oriented lamellar structures without the use of a special
neutral layer.
     Two samples of PMAPOSS-b-PTFEMA were successfully obtained via anionic polymerization and the purification of the resulting products with recycling preparative size exclusion chromatography. The BCPs used in this study had molecular weights of 32,000 g mol-1 and 22,000 g mol-1, with narrow polydispersity indices of 1.06 and 1.07, respectively. Subsequently, morphological characterization of the bulk sample was carried out by preparing samples from solvent evaporation in chloroform and analyzed with transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). The TEM images obtained clearly showed a line-like lamellar morphology and the peaks of the SAXS profile
obtained were characteristic to lamellae.
     Further studies were conducted in the thin film via atomic force microscopy (AFM). The BCP dissolved in chloroform was spin-casted onto silicon wafers to obtain a thin film with a thickness of approximately 30 nm. After optimizing the thermal annealing conditions to 150 °C for 1 min under air ambient conditions, AFM analyses were conducted that showed lines with a contrast between the PMAPOSS and PTFEMA domains. This is considered to be due the similar surface free energy between the two blocks. Oxygen plasma reactive ion etching was carried out on the annealed thin films and a trench line pattern of line width ca. 10 nm was obtained.
     Interestingly, the vertically oriented lamellae could be obtained on various substrates such as silicon wafers, glass plates and plastics without the use of a special neutral layer. The relatively short annealing time of one minute in air ambient conditions is favorable for the mass production of nano-patterns. Therefore, PMAPOSS-b-PTFEMA, with its characteristic sub-10 nm scale selfassembly and good etching contrast, can be one of the new candidates for next-generation sub-10 nm BCP nanolithography.

     As described above, the authors have demonstrated comprehensive fundamental research on a methodology for preparing BCPs for selfassembled nanostructures without special neutral layers. These interesting research results were presented at the Annual Conference of Photopolymer Science and Technology in 2015 and the paper was published in the Journal of photopolymer Science and Technology. This paper contributes to the understanding of the fundamental aspects to form self-assembled nanostructures.