Yoshihisa Yamashita

Bio: Yoshihisa Yamashita is an academic researcher from Panasonic. The author has contributed to research in topics: Layer (electronics) & Substrate (printing). The author has an hindex of 22, co-authored 107 publications receiving 2451 citations.

Low-temperature, high-performance solution-processed metal oxide thin-film transistors formed by a ‘sol–gel on chip’ process

Abstract: A low-temperature, solution-based preparation of amorphous, metal oxide semiconducting thin-films is reported. This ‘sol–gel on chip’ hydrolysis approach yields thin-film transistors with high field-effect mobilities, reproducible and stable turn-on voltages and high operational stability.

Electronic component built-in module and method of manufacturing the same

Abstract: An electronic component built-in module according to the present invention includes a pair of opposed circuit substrates, each of which includes a wiring pattern and an insulating base material containing a resin, an insulating layer that is placed between the pair of circuit substrates and contains an inorganic filler and a resin composition containing a thermosetting resin, an electronic component that is embedded in the insulating layer, and an inner via that is provided in the insulating layer so as to make an electrical connection between wiring patterns provided on different circuit substrates. A glass transition temperature Tg1 of the resin composition contained in the insulating layer and a glass transition temperature Tg2 of the insulating base material included in each of the circuit substrates satisfy a relationship Tg1>Tg2.

Transfer material, method for producing the same and wiring substrate produced by using the same

Abstract: A transfer material capable of transferring a fine wiring pattern to a substrate reliably and easily. The transfer material includes at least three layers of a first metal layer 101 as a carrier, a second metal layer 103 that is transferred to the substrate as a wiring pattern, and a peel layer 102 adhering the first and second metal layers releasably. On the surface portion of the first metal layer 101, a concave and convex portion corresponding to the wiring pattern is formed, and the peel layer 102 and the second metal layer 103 are formed on a region of the convex portions.

Magnetic sheet with stripe-arranged magnetic grains, RFID magnetic sheet, magnetic shielding sheet and method of manufacturing the same

Abstract: A water-repelling layer is formed on a resin film, and a stripe pattern region is formed so as to be positioned within a surface region of the water-repelling layer and so as to be relatively hydrophilic with respect to water repellency of the water-repelling layer. A magnetic stripe pattern is formed of needle-shaped magnetic grains oriented and aggregated in the stripe pattern region. The needle-shaped magnetic grains are arranged in a desirable state in a predetermined stripe pattern, with a high magnetic permeability and a magnetic sheet with stripe-arranged magnetic grains that is thin and flexible is obtained.

Flip chip mounting method and bump forming method

Abstract: A flip chip mounting method and a bump forming method which can be applied to next generation LSI flip chip mounting and have high productivity and reliability. In a state where a semiconductor chip (20) having a plurality of electrode terminals (12) is held to face a circuit board (21) having a plurality of connecting terminals (11) with a fixed space in between, the semiconductor chip (20) and the circuit board (21) are dipped for a prescribed time in dip bath (40) containing a molten resin (14) including a molten solder powder. In such dip step, as the molten solder powder is self-collected between the connecting terminal (11) of the circuit board (21) and the electrode terminal (12) of the semiconductor chip (20), a connecting body (22) is formed between the terminals. Then, the semiconductor chip (20) and the circuit board (21) are taken out from the dip bath (40), the molten resin (14) infiltrated in the space between the semiconductor chip (20) and the circuit board (21) is hardened, and a flip chip mounting body is completed.

Oxide Semiconductor Thin‐Film Transistors: A Review of Recent Advances

Abstract: Transparent electronics is today one of the most advanced topics for a wide range of device applications. The key components are wide bandgap semiconductors, where oxides of different origins play an important role, not only as passive component but also as active component, similar to what is observed in conventional semiconductors like silicon. Transparent electronics has gained special attention during the last few years and is today established as one of the most promising technologies for leading the next generation of flat panel display due to its excellent electronic performance. In this paper the recent progress in n- and p-type oxide based thin-film transistors (TFT) is reviewed, with special emphasis on solution-processed and p-type, and the major milestones already achieved with this emerging and very promising technology are summarizeed. After a short introduction where the main advantages of these semiconductors are presented, as well as the industry expectations, the beautiful history of TFTs is revisited, including the main landmarks in the last 80 years, finishing by referring to some papers that have played an important role in shaping transparent electronics. Then, an overview is presented of state of the art n-type TFTs processed by physical vapour deposition methods, and finally one of the most exciting, promising, and low cost but powerful technologies is discussed: solution-processed oxide TFTs. Moreover, a more detailed focus analysis will be given concerning p-type oxide TFTs, mainly centred on two of the most promising semiconductor candidates: copper oxide and tin oxide. The most recent data related to the production of complementary metal oxide semiconductor (CMOS) devices based on n- and p-type oxide TFT is also be presented. The last topic of this review is devoted to some emerging applications, finalizing with the main conclusions. Related work that originated at CENIMAT|I3N during the last six years is included in more detail, which has led to the fabrication of high performance n- and p-type oxide transistors as well as the fabrication of CMOS devices with and on paper.

Semiconductor device, and manufacturing method thereof

Abstract: An object is to provide a semiconductor device of which a manufacturing process is not complicated and by which cost can be suppressed, by forming a thin film transistor using an oxide semiconductor film typified by zinc oxide, and a manufacturing method thereof. For the semiconductor device, a gate electrode is formed over a substrate; a gate insulating film is formed covering the gate electrode; an oxide semiconductor film is formed over the gate insulating film; and a first conductive film and a second conductive film are formed over the oxide semiconductor film. The oxide semiconductor film has at least a crystallized region in a channel region.

Lab-on-Skin: A Review of Flexible and Stretchable Electronics for Wearable Health Monitoring

Abstract: Skin is the largest organ of the human body, and it offers a diagnostic interface rich with vital biological signals from the inner organs, blood vessels, muscles, and dermis/epidermis. Soft, flexible, and stretchable electronic devices provide a novel platform to interface with soft tissues for robotic feedback and control, regenerative medicine, and continuous health monitoring. Here, we introduce the term “lab-on-skin” to describe a set of electronic devices that have physical properties, such as thickness, thermal mass, elastic modulus, and water-vapor permeability, which resemble those of the skin. These devices can conformally laminate on the epidermis to mitigate motion artifacts and mismatches in mechanical properties created by conventional, rigid electronics while simultaneously providing accurate, non-invasive, long-term, and continuous health monitoring. Recent progress in the design and fabrication of soft sensors with more advanced capabilities and enhanced reliability suggest an impending t...

Metal oxides for optoelectronic applications

Abstract: Optical transparency, tunable conducting properties and easy processability make metal oxides key materials for advanced optoelectronic devices. This Review discusses recent advances in the synthesis of these materials and their use in applications. Metal oxides (MOs) are the most abundant materials in the Earth's crust and are ingredients in traditional ceramics. MO semiconductors are strikingly different from conventional inorganic semiconductors such as silicon and III–V compounds with respect to materials design concepts, electronic structure, charge transport mechanisms, defect states, thin-film processing and optoelectronic properties, thereby enabling both conventional and completely new functions. Recently, remarkable advances in MO semiconductors for electronics have been achieved, including the discovery and characterization of new transparent conducting oxides, realization of p-type along with traditional n-type MO semiconductors for transistors, p–n junctions and complementary circuits, formulations for printing MO electronics and, most importantly, commercialization of amorphous oxide semiconductors for flat panel displays. This Review surveys the uniqueness and universality of MOs versus other unconventional electronic materials in terms of materials chemistry and physics, electronic characteristics, thin-film fabrication strategies and selected applications in thin-film transistors, solar cells, diodes and memories.

Oxygen vacancies confined in ultrathin indium oxide porous sheets for promoted visible-light water splitting.

Abstract: Finding an ideal model for disclosing the role of oxygen vacancies in photocatalysis remains a huge challenge. Herein, O-vacancies confined in atomically thin sheets is proposed as an excellent platform to study the O-vacancy–photocatalysis relationship. As an example, O-vacancy-rich/-poor 5-atom-thick In2O3 porous sheets are first synthesized via a mesoscopic-assembly fast-heating strategy, taking advantage of an artificial hexagonal mesostructured In-oleate complex. Theoretical/experimental results reveal that the O-vacancies endow 5-atom-thick In2O3 sheets with a new donor level and increased states of density, hence narrowing the band gap from the UV to visible regime and improving the carrier separation efficiency. As expected, the O-vacancy-rich ultrathin In2O3 porous sheets-based photoelectrode exhibits a visible-light photocurrent of 1.73 mA/cm2, over 2.5 and 15 times larger than that of the O-vacancy-poor ultrathin In2O3 porous sheets- and bulk In2O3-based photoelectrodes.