Si (100)-GaN/Si (111) low temperature wafer bonding process for 3D power supply on chip

In this paper, we describe the wafer bonding technology Si (100) substrate and GaN/Si (111) substrate using surface activated bonding at room temperature and the removal technique for Si (111) substrate underneath the GaN and buffer layers for 3D power-supply on chip.9th IEEE CPMT Symposium Japan (ICSJ2019), 18-20 November, 2019, Kyoto University, Kyoto, Japa

Numerical predictions of a novel 3D stacked power-SoC structure based on hexagonal-BN

Recently, power-SoC has been attracting attentions because it can realize ultimate miniaturization of power supply. The silicon-on-insulator (SOI) technology is one of the promising candidates for realizing power-SoC because this technology is suitable for high frequency switching, that is resulting from its smaller parasitic capacitance. However, the conventional SOI structure has a problem of self-heating because of low thermal conductivity of SiO2. In such situations, hexagonal-BN(h-BN) is attractive for the buried insulator layer of SOI because it has higher thermal conductivity with atomically flat surface (Ra of h-BN < 0.25 nm). In this paper, we evaluate the thermal performance of a 3D stacked power SoC utilizing h-BN as an insulator and thermal interface material through numerical simulations. We also discuss the impact of the through-silicon-via (TSV) for heat dissipation.Integrated Power Conversion and Power Management (PwrSoc 2018), October 17-19, 2018, Hsinchu, Taiwa

Design consideration of a 3D stacked power supply on chip

In recent years, miniaturization and thinning of the power supply are attracted attentions. In this paper, we discuss the structure for the on-chip inductor and assembly technology suitable for 3D power SoC, which stacks GaN power device, passive devices, control circuit, and driver, based on wafer direct bonding technology and clarified the potential of the high frequency switching applications. We also propose the optimum structure and technology according to the switching frequency based on simulations.2018 IEEE 68th Electronic Components and Technology Conference (ECTC), 29 May-1 June 2018, San Diego, CA, US

Impact of the semiconductor on hexagonal-BN structure for power-supply on chip applications

This paper evaluates the semiconductor on hexagonal-BN (h-BN) structure for power-supply on chip applications based on numerical simulations. Hexagonal-BN is used as an insulator of semiconductor -on-insulator (SOI) structure. Hexagonal-BN based SOI structure with through-silicon-via(TSV) shows higher heat dissipation performance without degrading electrical characteristics compared with the conventional SOI structure.2018 International Conference on Solid State Devices and Materials(SSDM2018), September9-13, 2018, Hongo Campus, The University of Tokyo, Tokyo, Japa

Demonstration of periodic nanostructure formation with less ablation by double-pulse laser irradiation on titanium

By pairing femtosecond laser pulses (duration ∼40 fs and central wavelength ∼810 nm) at an appropriate time interval, a laser-induced periodic surface structure (LIPSS) is formed with much less ablation than one formed with a single pulse. On a titanium plate, a pair of laser pulses with fluences of 70 and 140 mJ/cm² and a rather large time interval (>10 ps) creates a LIPSS with an interspace of 600 nm, the same as that formed by a single pulse of 210 mJ/cm², while the double pulse ablates only 4 nm, a quarter of the ablation depth of a single pulse

Fluorescence and chemiluminescence behavior of distyrylbenzene bearing two arms of dipicolylaminomethyl groups: Interactions with zinc ion and ATP

Available online 31 January 2018.The absorption and fluorescence spectral study of the distyrylbenzene bearing two arms of the dipicolylaminomethyl groups, the effective ligands for Zn2+, was studied in the presence of Zn2+ and ATP. Upon complexation of the distyrylbenzene with zinc ions in acetonitrile, enhancement of the fluorescence intensity was observed due to inhibition of intramolecular PET (photo-induced electron transfer) quenching, but no effect was found in aqueous media because the equilibrium laid to the free form of the ligands. In contrast, the addition of ATP disodium salt was effective to enhance the fluorescence intensity of the combination of the distyrylbenzne and Zn2+ in aqueous media. This assembly was applied to the peroxyoxalate chemiluminescence system and a significant increase in the intensity was observed, which provides a potential detection for ATP by chemiluminescence. (C) 2018 Elsevier B.V. All rights reserved.ArticleSPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY. 195:223-229 (2018)journal articl

Open-label clinical trial of bezafibrate treatment in patients with fatty acid oxidation disorders in Japan

IntroductionFatty acid oxidation disorders (FAODs) are rare diseases caused by defects in mitochondrial fatty acid oxidation (FAO) enzymes. While the efficacy of bezafibrate, a peroxisome proliferator-activated receptor agonist, on the in vitro FAO capacity has been reported, the in vivo efficacy remains controversial. Therefore, we conducted a clinical trial of bezafibrate in Japanese patients with FAODs.Materials and methodsThis trial was an open-label, non-randomized, and multicenter study of bezafibrate treatment in 6 patients with very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency and 2 patients with carnitine palmitoyltransferase-II (CPT-2) deficiency (median age, 8.2 years; ranging from 5.8 to 26.4 years). Bezafibrate was administered for 6 months following a 6-month observation period. The primary endpoint was the frequency of myopathic attacks, and the secondary endpoints were serum acylcarnitines (ACs, C14:1 or C16 + C18:1), creatine kinase (CK) levels, degree of muscle pain (VAS; visual analog scale) during myopathic attacks, and quality of life (QOL; evaluated using validated questionnaires).ResultsThe frequency of myopathic attacks after bezafibrate administration decreased in 3 patients, increased in 3, and did not change in 2. The CK, AC, and VAS values during attacks could be estimated in only three or four patients, but a half of the patients did not experience attacks before or after treatment. Changes in CK, AC, and VAS values varied across individuals. In contrast, three components of QOL, namely, physical functioning, role limitation due to physical problems (role physical), and social functioning, were significantly elevated. No adverse drug reactions were observed.ConclusionIn this study, the frequency of myopathic attacks and CK, AC, and VAS values during the attacks could not be evaluated due to several limitations, such as a small trial population. Our findings indicate that bezafibrate improves the QOL of patients with FAODs, but its efficacy must be examined in future investigations

Proton beam therapy for bone sarcomas of the skull base and spine: A retrospective nationwide multicenter study in Japan

We conducted a retrospective, nationwide multicenter study to evaluate the clinical outcomes of proton beam therapy for bone sarcomas of the skull base and spine in Japan. Eligibility criteria included: (i) histologically proven bone sarcomas of the skull base or spine; (ii) no metastases; (iii) ≥20 years of age; and (iv) no prior treatment with radiotherapy. Of the 103 patients treated between January 2004 and January 2012, we retrospectively analyzed data from 96 patients who were followed-up for >6 months or had died within 6 months. Seventy-two patients (75.0%) had chordoma, 20 patients (20.8%) had chondrosarcoma, and four patients (7.2%) had osteosarcoma. The most frequent tumor locations included the skull base in 68 patients (70.8%) and the sacral spine in 13 patients (13.5%). Patients received a median total dose of 70.0 Gy (relative biological effectiveness). The median follow-up was 52.6 (range, 6.3–131.9) months. The 5-year overall survival, progression-free survival, and local control rates were 75.3%, 49.6%, and 71.1%, respectively. Performance status was a significant factor for overall survival and progression-free survival, whilst sex was a significant factor for local control. Acute Grade 3 and late toxicities of ≥Grade 3 were observed in nine patients (9.4%) each (late Grade 4 toxicities [n = 3 patients; 3.1%]). No treatment-related deaths occurred. Proton beam therapy is safe and effective for the treatment of bone sarcomas of the skull base and spine in Japan. However, larger prospective studies with a longer follow-up are warranted