永井研究室では最先端のAPTやFIB、TEMといった機器を扱いながらさまざまな研究を行っています

● 研 究 紹 介 ●

３次元アトムプローブ法を用いて、シリコンやゲルマニウムなどの半導体を基盤とするトランジスタ構造の評価を行っています。 ３次元アトムプローブ法は固体材料中の原子１個１個を実空間且つ原子レベルで観測できる手法 であり、今後は多種多様な材料の評価が期待されています。この一連の研究を通じて、固体中の原子間の相互作用や不純物原子クラスター形成メカニズムなどの基礎的な物理現象の解明を目指しています。 最近では、半導体材料のみならず、これまで測定が難しいとされてきた絶縁体・セラミック材料の評価にも取り組んでいます。


半導体関連の３次元アトムプローブ評価の詳細は、解説論文：

• ３次元アトムプローブによる半導体ナノ構造の元素分布解析
  日本真空学会誌 解説　第56巻, 第9号, pp. 340-347 (2013).
  
• Industrial application of atom probe tomography to semiconductor devices
  Scripta Materialia, Vol. 148, pp. 82-90 (2018).

をご覧下さい。


● ニ ュ ー ス ●（2020.3.2更新）

【会議・研究会・セミナー】

• 第67回応用物理学会春季学術講演会（上智大学四谷キャンパス、2020.3.12-15開催）に参加予定でした。
• MRS Fall Meeting & Exhibit 2019（ボストン、米国、2019.12.1-6開催）にて発表しました。
• 第22回二次イオン質量分析国際会議（SIMS22）（みやこめっせ、京都、2019.10.20-25開催）にて発表しました。

【論文】

• 大阪市立大学との共同研究で、常温で直接接合した銅-ダイヤモンド界面のナノ構造評価（熱処理の効果）について、ACS Applied Nano Materials誌に掲載されました。
• 慶應義塾大学と東北大学国際集積エレクトロニクス研究開発センターとの共同研究で、酸化シリコンナノピラー中のシリコン自己拡散評価について、Journal of Applied Physics誌に掲載されました。
• 香港城市大学との共同研究で、FeCoNiCrTi_0.2の機械的特性およびアトムプローブ評価について、Acta Materialia誌に掲載されました。

☆ 書籍の紹介 ☆

● 職 歴 ●

• 2020.4- 2020.4東北大学 金属材料研究所 学術研究員
• 2010.4- 2020.3東北大学 金属材料研究所 材料照射工学研究部門 助教
• 2009.4- 2010.1Post-Doctoral Researcher
  Department of Metallurgy and Materials Engineering
  Katholieke Universiteit Leuven (Belgium) and IMEC vzw
• 2008.4- 2010.3独立行政法人日本学術振興会 特別研究員
• 2007.10- 2009.3慶應義塾大学大学院 グローバルCOE RA研究員

● 外 部 委 員 ●

• 2018.10- 現在Program Committee
  22nd International Conference on SIMS
• 2017.4- 現在システムデバイスロードマップ（SDRJ）委員会委員
  ワーキンググループ：Metrology
• 2016.6- 2017.8Local Program Sub-Committee (Materials Characterization)
  International Conference on Defects in Semiconductors
• 2014.4- 現在SIMS国際シンポジウム（SISS）幹事会委員
• 2014.6- 2016.3電子情報技術産業協会半導体技術ロードマップ専門委員会
  専門部会WG14（計測）特別委員

● 学 歴 ●

• 2006.4- 2009.3慶應義塾大学大学院 理工学研究科
  基礎理工学専攻 博士課程 ［博士（工学）］
• 2004.4- 2006.3慶應義塾大学大学院 理工学研究科 基礎理工学専攻 修士課程
• 2000.4- 2004.3慶應義塾大学 理工学部 学門1（物理情報工学科）

● 受 賞 ●

• 2017.4Poster Award／64th JSAP Spring Meeting 2017（筆頭：Yuan TU）
• 2016.6Best Poster Award／Atom Probe Tomography & Microscopy 2016
• 2013.5優秀ポスター賞／第125回2013年春季東北大学金属材料研究所講演会
• 2012.11MRS Outstanding Poster Award
  Materials Research Society (MRS) Fall Meeting 2012
• 2011.3MIRAI賞最優秀賞／次世代半導体材料・プロセス基盤プロジェクト
• 2009.3Distinguished Research Associate 2008／Keio G-COE Program
• 2008.3First Prize／Keio-Gent G-COE Joint Workshop for Future Network
• 2008.3First Prize／Final Report 2007 in Keio G-COE Program
• 2007.11Student Award／第16回二次イオン質量分析に関する国際会議
• 2006.8第20回応用物理学会講演奨励賞／第53回春季応用物理学関係連合講演会
• 2006.3専修主任賞／慶應義塾大学大学院理工学研究科 基礎理工学専攻 応用物理専修

● 競争的資金・助成金 ●



日本の研究.com

【代表者】
【分担者として参画】

● 招 待 講 演 ●

1. Dopant behavior in semiconductor materials and nanostructures analyzed by atom probe tomography
   第19回「イオンビームによる表面・界面解析」特別研究会
   京都大学宇治キャンパス, 2018年12月.
   
2. Atom probe study of silicon-based device structures
   Atom Probe Tomography and Microscopy (APT&M) 2018, NIST, Gaithersburg, Maryland, USA, June 2018.
   
3. ３次元アトムプローブ法を用いた材料解析：原理と応用
   日本学術振興会 結晶加工と評価技術 第145委員会 第156回研究会
   明治大学駿河台キャンパス グローバルフロント, 2017年12月.
   
4. Atom probe study of semiconductor-based nanostructure
   IUMRS-ICAM 2017, Kyoto University, August 2017.
   
5. Dopant detection in silicon nanostructures by atom probe tomography
   4th Bilateral Italy-Japan Seminar: Innovative Solutions for Single Atom Applications in Photonics and Nanoelectronics, Colico, Lago di Como, Italy, May 2017.
   
6. Atom probe tomography of semiconductor and oxide materials
   第26回日本MRS年次大会, 横浜, 2016年12月.
   
7. 先端デバイス開発のための３次元アトムプローブ分析技術の応用例
   カメカテクニカルセミナー2016 [プログラムPDF版]
   くるまプラザ（港区芝大門）, 2016年11月.
   
8. 先端ナノエレクトロニクス材料の元素分布分析
   第106回総研セミナー, 東京都市大学 総合研究所, 2016年4月.
   
9. 3D-APの半導体応用の現状と最近の話題
   日本学術振興会 ナノプローブテクノロジー 第167委員会 第81回研究会
   東京大学駒場キャンパス コンベンションホール, 2016年1月.
   
10. 半導体デバイス中のドーパント分布解析に向けた３次元アトムプローブの利用
    電子情報技術産業協会（JEITA）半導体技術ロードマップ専門委員会（STRJ）
    故障解析SWG 第62回会合, メルパルク京都, 2015年12月.
    
11. Panel Session: Dopant Visualization
    第35回ナノテスティングシンポジウム (NanoTS 2015)
    千里ライフサイエンスセンター, 2015年11月.
    
12. Elemental distributions in semiconductor-based device structures analyzed by atom probe tomography
    2015 International Symposium for Advanced Materials Research (ISAMR), Sun Moon Lake, Taiwan, August 2015.
    
13. 3D atomic-scale-analysis of elemental distribution in silicon nanoelectronics
    3rd Bilateral Italy-Japan Seminar: Silicon Nanoelectronics for Advanced Applications, Campus Plaza Kyoto, Japan, June 2015.
    
14. ３次元アトムプローブを用いた材料中の元素分布評価 ～半導体を例に～
    一般財団法人 材料科学技術振興財団, 2015年2月.
    
15. ３次元アトムプローブを用いた材料解析例
    電子顕微鏡解析技術分科会フォーラム [プログラムPDF版］, 時之栖, 2014年8月.
    
16. Assessment of tooth composition by atom probe tomography
    Student Chapter Research Meeting
    Tokyo Medical and Dental University, June 2014.
    
17. ３次元アトムプローブによる半導体材料・デバイス中の元素分布評価～アトムプローブの標準化活動を念頭に～
    表面化学分析技術国際標準化委員会（JSCA）WG
    東京八重洲ホール, 2013年12月.
    
18. ３次元アトムプローブによる半導体ナノ構造中の元素分布評価例
    カメカテクニカルセミナー2013 [プログラムPDF版]
    くるまプラザ（港区芝大門）, 2013年11月.
    
19. ３次元アトムプローブによる半導体デバイス中のドーパント分布解析
    日本学術振興会 材料の微細組織と機能性 第133委員会 第218回研究会
    東京工業大学キャンパス イノベーションセンター, 2013年10月.
    
20. Elemental distribution analysis in semiconductor-based MOS devices with atom probe tomography
    2013 JSAP-MRS Symposia
    Doshisha University, Kyoto, Japan, September 2013.
    
21. 半導体デバイスの３次元アトムプローブ解析
    第29回分析電子顕微鏡討論会, 幕張メッセ国際会議場, 2013年9月.
    
22. Dopant analysis of semiconductor devices with atom probe tomography
    15th International Symposium on SIMS and Related Techniques Based on Ion-Solid Interactions at Seikei University (SISS-15)
    Tokyo, Japan, April 2013.
    
23. ３次元アトムプローブによる半導体デバイス中の元素分布解析
    電子情報技術産業協会（JEITA）半導体技術ロードマップ専門委員会（STRJ）
    WG14専門部会（メトロロジ：計測WG）, JEITA会議室, 2013年1月.
    
24. 三次元アトムプローブによるシリコンMOSデバイス材料の評価
    カメカテクニカルセミナー2011, くるまプラザ（港区芝大門）, 2011年11月.
    
25. Characterization of three-dimensional dopant distribution in MOSFETs by atom probe
    1st Annual World Congress of Nano-S&T
    The Dalian World Expo Center, Dalian, China, October 2011.
    
26. 3D-AP法によるSi-MOSFET中不純物分布解析
    日本学術振興会 ナノプローブテクノロジー 第167委員会 第63回研究会
    慶應義塾大学日吉キャンパス, 2011年7月.
    
27. CMOS process monitoring using silicon isotopes
    Companion Workshop "Impact of METROLOGY on TCAD" in 2008 International Conference on Simulation of Semiconductor Processes and Devices, Hakone, Japan, September 2008.
    

● 論 文 ●

更新日： 2020年4月2日
| Publons | ORCID | ResearchGate | Scopus | Google Scholar | researchmap | Dimensions |

- 2020 -



1. Characterization of nanoscopic Cu/diamond interfaces prepared by surface activated bonding: Implications for thermal management
   J. Liang, Y. Ohno, Y. Yamashita, Y. Shimizu, S. Kanda, N. Kamiuchi, S.-W. Kim , K. Koyama, Y. Nagai, M. Kasu, and N. Shigekawa
   ACS Applied Nano Materials, Vol. 3, Issue 3, pp. 2455-2462 (2020).
   
   The microstructures of Cu/diamond interfaces prepared by surface-activated bonding at room temperature are examined by cross-sectional scanning transmission electron microscopy (STEM). A crystalline defect layer composed of Cu and diamond with a thickness of approximately 4.5 nm is formed at the as-bonded interface, which is introduced by irradiation with an Ar beam during the bonding process. No crystalline defect layer is observed at the 700 ^oC-annealed interface, which is attributed to the recrystallization of the defect layer due to the high-temperature annealing process. Instead of the defect layer, a mating interface layer and a copper oxide layer are formed at the interface. The mating interface layer and the copper oxide layer play a role in relieving the residual stress caused by the different thermal expansion coefficients of diamond and Cu. The thermal boundary resistance (TBR) of the as-bonded interface is measured to be 1.7±0.2×10^-8 m²K/W by the time domain pulsed-light-heating thermoreflectance technique. These results indicate that the direct bonding of diamond and Cu is a very effective technique for improving the heat-dissipation performance of power devices.
   
   
2. Oxidation-enhanced Si self-diffusion in isotopically modulated silicon nanopillars
   R. Kiga, S. Hayashi, S. Miyamoto, Y. Shimizu, Y. Nagai, T. Endoh, and K. M. Itoh
   Journal of Applied Physics, Vol. 127, Issue 4, 045704 (2020) (6 pages).
   
   
   Silicon (Si) self-diffusivity in a Si nanopillar under dry oxidation was quantitatively evaluated by atom probe tomography of Si isotope heterostructure interfaces. Dry oxidation of a nanopillar with 200 nm in diameter at 920 ^oC for 4 hours revealed that the Si self-diffusivity was the same as the one measured for the standard planar oxidation despite the fact that the diffusion region probed in the pillar was surrounded by ∼7 times more oxidation interface areas than the simple planar oxidation case. This finding can be understood by considering the large diffusion length ∼300 µm of the interstitials for our thermal oxidation condition. The excess interstitials injected by the pillar oxidation as well as those injected by the oxidation of the base (100) plane can easily diffuse through the sample, including interiors of the pillars, making the concentration of the excess interstitials practically equal to those injected for the (100) planar oxidation case.
   
   
3. Impact of focused ion beam on structural and compositional analysis of interfaces fabricated by surface activated bonding
   Y. Ohno, H. Yoshida, N. Kamiuchi, R. Aso, S. Takeda, Y. Shimizu, Y. Nagai, J. Liang, and N. Shigekawa
   Japanese Journal of Applied Physics, Vol. 59, No. SB, SBBB05 (2020) (5 pages).
   
   
   We have shown that the structural and compositional properties of semiconductor interfaces fabricated by surface activated bonding (SAB) would be modified during focused ion beam (FIB) processes operated at room temperature (RT), especially for wide band-gap materials, and such a modification can be suppressed by FIB processes operated at lower temperatures. During FIB processes operated at RT, SAB-fabricated Si/Si and GaAs/GaAs interfaces are amorphized along the interfaces, even at the internal locations deeper than the penetration depth of the FIB, and the impurity distribution across the interfaces is modified. This phenomenon is presumably due to the atomic diffusion assisted by the point defects that are introduced by FIB irradiation. By using FIB processes operated at -150 ^oC, the FIB-induced atomic diffusion would be ignored for Si/Si interfaces. Meanwhile, the diffusion would be still effective for GaAs/GaAs interfaces, presumably due to the effects of recombination-enhanced defect motion under FIB irradiation.
   
   
4. Fabrication of diamond/Cu direct bonding for power device applications
   S. Kanda, Y. Shimizu, Y. Ohno, K. Shirasaki, Y. Nagai, M. Kasu, N. Shigekawa, and J. Liang
   Japanese Journal of Applied Physics, Vol. 59, No. SB, SBBB03 (2020) (5 pages).
   
   
   Direct bonding of diamond and Cu was successfully fabricated by surface activated bonding (SAB) method at room temperature. The interfacial structure of the diamond/Cu bonding interface was investigated by transmission electron microscope (TEM) and electron energy-loss spectroscopy (EELS). The effect of heat treatment temperature on the interface structure was also investigated. 4-nm-thick damaged layer was formed at the as-bonded interface, the damaged layer thickness decreased with annealing temperature rise. It was found that the atomic ratio of sp² bonding in the bonding interface was larger than that of the diamond separated from the interface by approximately 50 nm, which indicated that the damaged layer was composed of the amorphous or graphite and diamond. After annealing at 700 ^oC, a composite layer of about 2 nm thick was observed at the interface. There were no nanovoids and micro-cracks observed at the interface with annealing at a temperature as high as 700 ^oC. These results indicated that the diamond/Cu bonding interface has high thermal stability and can withstand the temperature rise of power devices during operating.
   
   
   

   - 2019 -

   
   
5. Atom probe tomography of GaAs homointerfaces fabricated by surface-activated bonding
   Y. Shimizu, N. Ebisawa, Y. Ohno, J. Liang, N. Shigekawa, K. Inoue, and Y. Nagai
   Proceedings of 2019 6th International Workshop on Low Temperature Bonding for 3D Integration (LTB-3D), p. 56, ISBN: 978-4-9047-4307-2
   
   
6. Artifacts in the structural analysis of SAB-fabricated interfaces by using focused ion beam
   Y. Ohno, H. Yoshida, N. Kamiuchi, R. Aso, S. Takeda, Y. Shimizu, N. Ebisawa, Y. Nagai, J. Liang, and N. Shigekawa
   Proceedings of 2019 6th International Workshop on Low Temperature Bonding for 3D Integration (LTB-3D), p. 55, ISBN: 978-4-9047-4307-2
   
   
7. Outstanding tensile properties of a precipitation-strengthened FeCoNiCrTi_0.2 high-entropy alloy at room and cryogenic temperatures
   Y. Tong, D. Chen, B. Han, J. Wang, R. Feng, T. Yang, C. Zhao, Y. L. Zhao, W. Guo, Y. Shimizu, C. T. Liu, P. K. Liaw, K. Inoue, Y. Nagai, A. Hu, and J. J. Kai
   Acta Materialia, Vol. 165, pp. 228-240 (2019).
   
   
   A FeCoNiCrTi_0.2 high-entropy alloy strengthened by two types of coherent nano-precipitates but with the same composition was fabricated, and its tensile properties at room (293 K) and cryogenic temperatures (77 K) and the corresponding defect-structure evolution were investigated. Compared with the single-phase FeCoNiCr parent alloy, the precipitation-strengthened FeCoNiCrTi_0.2 high-entropy alloy exhibits a significant increase in yield strength and ultimate tensile strength but with little sacrifice in ductility. Similar to the single-phase FeCoNiCr high-entropy alloy, the deformation behavior of this precipitation-strengthened FeCoNiCrTi_0.2 high-entropy alloy shows strong temperature dependence. When the temperature decreases from 293 K to 77 K, its yield strength and ultimate tensile strength are increased from 700 MPa to 860 MPa and from 1.24 to 1.58 GPa, respectively, associated with a ductility improvement from 36% to 46%. However, different from the single-phase FeCoNiCr high-entropy alloy with a twinning-dominant deformation mode at 77 K, multiple-layered stacking faults with a hierarchical substructure prevail in the precipitation-strengthened FeCoNiCrTi_0.2 high-entropy alloy when deformed at 77 K. The mechanism of twinning inhibition in this precipitation-strengthened high-entropy alloy is the high energy barrier for twin nucleation in the ordered γ' nano-particles. Our results may provide a guide for the design of tough high-entropy alloys for applications at cryogenic temperatures through combining precipitation strengthening and twinning/stacking faults.
   
   
   

   - 2018 -

   
   
8. Effect of carbon on boron diffusion and clustering in silicon: Temperature dependence study
   Y. Tu, Y. Shimizu, Y. Kunimune, Y. Shimada, T. Katayama, T. Ide, M. Inoue, F. Yano, K. Inoue, and Y. Nagai
   Journal of Applied Physics, Vol. 124, Issue 15, 155702 (2018) (8 pages).
   
   
   Atom probe tomography and secondary ion mass spectrometry were used to investigate the effects of carbon (C) co-implantation and subsequent annealing at 600 to 1200 ^oC on the behavior of implanted boron (B) atoms in silicon. When B alone was implanted, annealing at 600 to 800 ^oC caused it to form clusters in the peak region (10²⁰ cm^-3) of the concentration profile, and diffusion only occurred in the low-concentration tail region (< 10¹⁸ cm^-3), which is thought to be the well-known transient enhanced diffusion. However, when co-implantation with C was performed, this diffusion was almost completely suppressed in the same annealing temperature range. In the absence of C implantation, annealing at 1000 ^oC caused B clusters to begin to dissolve and B to diffuse out of the peak concentration region. However, this diffusion was also suppressed by C implantation because C atoms trapped B atoms in the kink region found at the B concentration level of 2×10¹⁹ cm^-3. At 1200 ^oC, B clusters were totally dissolved and strong B diffusion occurred. In contrast to lower annealing temperatures, this diffusion was actually enhanced by C implantation. It is believed that Si interstitials play an important role in the interaction between B and C. This kind of comprehensive investigation yields important information for optimizing ion implantation and annealing processes.
   
   
9. Industrial application of atom probe tomography to semiconductor devices
   A. D. Giddings, S. Koelling, Y. Shimizu, R. Estivill, K. Inoue, W. Vandervorst, and W. K. Yeoh
   Scripta Materialia, Vol. 148, pp. 82-90 (2018).
   Viewpoint set
   
   
   Advanced semiconductor devices offer a metrology challenge due to their small feature size, diverse composition and intricate structure. Atom probe tomography (APT) is an emerging technique that provides 3D compositional analysis at the atomic-scale; as such, it seems uniquely suited to meet these challenges. However, the semiconductor industry has demanding requirements against which the techniques in use are evaluated. This article explores the use of APT in the semiconductor industry, showing the potential of the technique, the obstacles that occur in practise, and possible future developments.
   
   
10. Composition evolution of gamma prime nanoparticles in the Ti-doped CoFeCrNi high entropy alloy
    B. Han, J. Wei, Y. Tong, D. Chen, Y. Zhao, J. Wang, F. He, T. Yang, C. Zhao, Y. Shimizu, K. Inoue, Y. Nagai, A. Hu, C.-T. Liu, and J.-J. Kai
    Scripta Materialia, Vol. 148, pp. 42-46 (2018).
    
    
    The composition evolution of γ' nanoparticles as a function of aging duration in the Ti-doped CoFeCrNi high entropy alloy was studied by atom probe tomography (APT) and first-principle calculations. The APT results indicate that the evolution behaviors of Co, Fe, and Cr in the Ni₃Ti-type γ' nanoparticles are significantly different. Co saturates to a stable concentration in the γ' nanoparticles rapidly in the initial stage of the precipitation, whereas Fe and Cr atoms are incorporated into the γ' nanoparticles during the coarsening. The APT results are supported by the first-principle calculations from the perspective of the electronic state.
    
    
11. Blocking of deuterium diffusion in poly-Si/Al₂O₃/Hf_xSi_1-xO₂/SiO₂ high-k stacks as evidenced by atom probe tomography
    Y. Tu, B. Han, Y. Shimizu, Y. Kunimune, Y. Shimada, T. Katayama, T. Ide, M. Inoue, F. Yano, K. Inoue, and Y. Nagai
    Applied Physics Letters, Vol. 112, Issue 3, 032902 (2018) (5 pages).
    
    
    Hydrogen (H) plays an important role in determining the reliability and performance of HfO₂- and Al₂O₃-based high-k dielectric electronic devices. In order to understand H behavior, deuterium (D), an isotope of H, was introduced into the poly-Si cap of Al₂O₃/Hf_xSi_1-xO₂/SiO₂ high-k stacks by ion implantation. Atom probe tomography was used to image the D distribution in samples annealed under different conditions. The results clearly demonstrated that the D atoms were trapped at the interface of poly-Si and Al₂O₃ after annealing at 900 K for 10 min. Thus, it is possible that Al₂O₃ blocks the H atoms at the surface, preventing them from diffusing into the high-k dielectrics during the H₂ annealing process in current fabrication technology. The current work also exhibits an example of investigating H behavior in semiconductors by atom probe tomography.
    
    
    

    - 2017 -

    
    
12. Nanoscopic analysis of oxygen segregation at tilt boundaries in silicon ingots using atom probe tomography combined with TEM and ab initio calculations
    Y. Ohno, K. Inoue, K. Fujiwara, K. Kutsukake, M. Deura, I. Yonenaga, N. Ebisawa, Y. Shimizu, K. Inoue, Y. Nagai, H. Yoshida, S. Takeda, S. Tanaka, and M. Kohyama
    Journal of Microscopy, Vol. 268, Issue 3, pp. 230-238 (2017).
    
    
    We have developed ananalyticalmethod to determine the segregation levels on the same tilt boundaries (TBs) at the same nanoscopic location by a joint use of atom probe tomography and scanning transmission electron microscopy, and discussed the mechanism of oxygen segregation at TBs in silicon ingots in terms of bond distortions around the TBs. The three-dimensional distribution of oxygen atoms was determined at the typical small- and large-angle TBs by atom probe tomography with a low impurity detection limit (0.01 at.% on a TB plane) simultaneously with high spatial resolution (about 0.4 nm). The three-dimensional distribution was correlated with the atomic stress around the TBs; the stress at largeangle TBs was estimated by ab initio calculations based on atomic resolution scanning transmission electronmicroscopy data and that at small-angle TBs were calculated with the elastic theory based on dark-field transmission electron microscopy data. Oxygen atoms would segregate at bond-centred sites under tensile stress above about 2 GPa, so as to attain a more stable bonding network by reducing the local stress. The number of oxygen atoms segregating in a unit TB area N_GB (in atoms nm^-2) was determined to be proportional to both the number of the atomic sites under tensile stress in a unit TB area nbc and the average concentration of oxygen atoms around the TB [O_i] (in at.%) with N_GB ∼50n_bc[O_i].
    
    
13. 1.54 μm photoluminescence from Er:O_x centers at extremely low concentration in silicon at 300 K
    M. Celebrano, L. Ghirardini, M. Finazzi, Y. Shimizu, Y. Tu, K. Inoue, Y. Nagai, T. Shinada, Y. Chiba, A. Abdelghafar, M. Yano, T. Tanii, and E. Prati
    Optics Letters, Vol. 42, Issue 17, pp. 3311-3314 (2017).
    arXiv: 1702.00331
    
    
    The demand for single photon sources at λ = 1.54 μm, which follows from the consistent development of quantum networks based on optical fiber technologies, makes Er:Ox centers in Si a viable resource, thanks to the optical transition of Er³⁺: ⁴I_13/2 → ⁴I_15/2. Yet, to date, the implementation of such system in applications remains hindered by its extremely low emission rate. In this Letter, we explore the room-temperature photoluminescence (PL) at the telecomm wavelength from very low implantation doses of Er:O_x in Si. The emitted photons, excited by a λ = 792 nm laser in both large areas and confined dots of diameter down to 5 μm, are collected by an inverted confocal microscope. The lower-bound number of optically active emission centers detectable within our diffraction-limited illumination spot is estimated to be of the order of 10², corresponding to a higher-bound value for the emission rate per individual ion of about 10⁴ s^-1.
    
    
14. Atom probe tomographic assessment of the distribution of germanium atoms implanted in a silicon matrix through nano-apertures
    Y. Tu, B. Han, Y. Shimizu, K. Inoue, Y. Fukui, M. Yano, T. Tanii, T. Shinada, and Y. Nagai
    Nanotechnology, Vol. 28, No. 38, 385301 (2017) (7 pages).
    
    
    Ion implantation through nanometer-scale apertures (nano-apertures) is a promising method to precisely position ions in silicon matrices, which is a requirement for next generation electronic and quantum computing devices. This paper reports the application of atom probe tomography (APT) to investigate the three-dimensional distribution of germanium atoms in silicon after implantation through nano-aperture of 10 nm in diameter, for evaluation of the amount and spatial distribution of implanted dopants. The experimental results obtained by APT are consistent with a simple simulation with consideration of several effects during lithography and ion implantation, such as channeling and resist flow.
    
    
15. Revisiting room-temperature 1.54 μm photoluminescence of ErO_x centers in silicon at extremely low concentration
    E. Prati, M. Celebrano, L. Ghirardini, P. Biagioni, M. Finazzi, Y. Shimizu, Y. Tu, K. Inoue, Y. Nagai, T. Shinada, Y. Chiba, A. Abdelghafar, M. Yano, and T. Tanii
    Proceedings of 2017 Silicon Nanoelectronics Workshop (SNW), pp. 105-106, ISSN 2161-4644
    
    
16. Atom probe study of erbium and oxygen co-implanted silicon
    Y. Shimizu, Y. Tu, A. Abdelghafar, M. Yano, Y. Suzuki, T. Tanii, T. Shinada, E. Prati, M. Celebrano, M. Finazzi, L. Ghirardini, K. Inoue, and Y. Nagai
    Proceedings of 2017 Silicon Nanoelectronics Workshop (SNW), pp. 99-100, ISSN 2161-4644
    
    
17. Impact of local atomic stress on oxygen segregation at tilt boundaries in silicon
    Y. Ohno, K. Inoue, K. Fujiwara, K. Kutsukake, M. Deura, I. Yonenaga, N. Ebisawa, Y. Shimizu, K. Inoue, Y. Nagai, H. Yoshida, S. Takeda, S. Tanaka, and M. Kohyama
    Applied Physics Letters, Vol. 110, Issue 6, 062105 (2017) (5 pages).
    
    
    Using the atom probe tomography, transmission electron microscopy, and ab initio calculations, we investigate the three-dimensional distributions of oxygen atoms segregating at the typical largeangle grain boundaries (GBs) (Σ3{111}, Σ9{221}, Σ9{114}, Σ9{111}/{115}, and Σ27{552}) in Czochralski-grown silicon ingots. Oxygen atoms with a covalent radius that is larger than half of the silicon’s radius would segregate at bond-centered positions under tensile stresses above about 2 GPa, so as to attain a more stable bonding network by reducing the local stresses. The number of oxygen atoms segregating in a unit GB area N_GB (in atoms/nm²) is hypothesized to be proportional to both the number of the tensilely-stressed positions in a unit boundary area n_bc and the average concentration of oxygen atoms around the boundary [O_i] (in at. %) with N_GB ∼50n_bc[O_i]. This indicates that the probability of oxygen atoms at the segregation positions would be, on average, fifty times larger than in bond-centered positions in defect-free regions.
    
    
18. Weak-beam scanning transmission electron microscopy for quantitative dislocation density measurement in steels
    K. Yoshida, M. Shimodaira, T. Toyama, Y. Shimizu, K. Inoue, T. Yoshiie, K. J. Milan, R. Gerard, and Y. Nagai
    Microscopy, Vol. 66, Issue 2, pp. 120-130 (2017).
    EDITOR'S CHOICE
    
    
    To evaluate dislocations induced by neutron irradiation, we developed a weak-beam scanning transmission electron microscopy (WB-STEM) system by installing a novel beam selector, an annular detector, a high-speed CCD camera and an imaging filter in the camera chamber of a spherical aberration-corrected transmission electron microscope. The capabilities of the WB-STEM with respect to wide-view imaging, real-time diffraction monitoring and multi-contrast imaging are demonstrated using typical reactor pressure vessel steel that had been used in an European nuclear reactor for 30 years as a surveillance test piece with a fluence of 1.09×10²⁰ neutrons cm^-2 The quantitatively measured size distribution (average loop size = 3.6±2.1 nm), number density of the dislocation loops (3.6×10²² m^-3) and dislocation density (7.8×10¹³ m m^-3) were carefully compared with the values obtained via conventional weak-beam transmission electron microscopy studies. In addition, cluster analysis using atom probe tomography (APT) further demonstrated the potential of the WB-STEM for correlative electron tomography/APT experiments.
    
    
19. Influence of laser power on atom probe tomographic analysis of boron distribution in silicon
    Y. Tu, H. Takamizawa, B. Han, Y. Shimizu, K. Inoue, T. Toyama, F. Yano, A. Nishida, and Y. Nagai
    Ultramicroscopy, Vol. 173, pp. 58-63 (2017).
    
    
    The relationship between the laser power and the three-dimensional distribution of boron (B) in silicon (Si) measured by laser-assisted atom probe tomography (APT) is investigated. The ultraviolet laser employed in this study has a fixed wavelength of 355 nm. The measured distributions are almost uniform and homogeneous when using low laser power, while clear B accumulation at the low-index pole of single-crystalline Si and segregation along the grain boundaries in polycrystalline Si are observed when using high laser power (100 pJ). These effects are thought to be caused by the surface migration of atoms, which is promoted by high laser power. Therefore, for ensuring a high-fidelity APT measurement of the B distribution in Si, high laser power is not recommended.
    
    
    

    - 2016 -

    
    
20. Boron distributions in individual core-shell Ge/Si and Si/Ge heterostructured nanowires
    B. Han, Y. Shimizu, J. Wipakorn, K. Nishibe, Y. Tu, K. Inoue, N. Fukata, and Y. Nagai
    Nanoscale, Vol. 8, Issue 47, pp. 19811-19815 (2016).
    
    
    Ge/Si and Si/Ge core-shell nanowires (NWs) have substantial potential for application in many kinds of devices. Because the impurity distributions in Ge/Si and Si/Ge core-shell NWs strongly affect their electrical properties, which in turn affect device performance, this issue needs urgent attention. Here we report an atom probe tomographic study of the distribution of boron (B), one of the most important impurities, in two kinds of NWs. B atoms were doped into the Si regions of Ge/Si and Si/Ge core-shell NWs. It was found that B atoms randomly distributed in the Si shell of the Ge/Si core-shell NWs. In the Si/Ge core-shell NWs, on the other hand, the B distributions depended on the growth temperature and the B₂H₆ flux. With higher growth temperature and increased B₂H₆ flux, B atoms piled up in the outer region of the Si core. However, B atoms were observed to be randomly distributed in the Si core after decreasing both the growth temperature and the B₂H₆ flux.
    
    
21. Recombination activity of nickel, copper, and oxygen atoms segregating at grain boundaries in mono-like silicon crystals
    Y. Ohno, K. Kutsukake, M. Deura, I. Yonenaga, Y. Shimizu, N. Ebisawa, K. Inoue, Y. Nagai, H. Yoshida, and S. Takeda
    Applied Physics Letters, Vol. 109, Issue 14, 142105 (2016) (4 pages).
    
    
    Three-dimensional distribution of impurity atoms was determined at functional Σ5{013} and smallangle grain boundaries (GBs) in as-grown mono-like silicon crystals by atom probe tomography combined with transmission electron microscopy, and it was correlated with the recombination activity of those GBs, C_GB, revealed by photoluminescence imaging. Nickel (Ni), copper (Cu), and oxygen atoms preferentially segregated at the GBs on which arrays of dislocations existed, while those atoms scarcely segregated at Σ5{013} GBs free from dislocations. Silicides containing Ni and Cu about 5 nm in size and oxides about 1 nm in size were formed along the dislocation arrays on those GBs. The number of segregating impurity atoms per unit GB area for Ni and that for Cu, N_Ni and N_Cu, were in a trade-off correlation with that for oxygen, N_O, as a function of C_GB, while the sum of those numbers was almost constant irrespective of the GB character, C_GB, and the dislocation density on GBs. C_GB would be explained as a linear combination of those numbers: C_GB (in %)∼400 (0.38N_O+N_N+N_Cu) (in atoms/nm²). The GB segregation of oxygen atoms would be better for solar cells, rather than that of metal impurities, from a viewpoint of the conversion efficiency of solar cells.
    
    
22. Predoping effects of boron and phosphorous on arsenic diffusion along grain boundaries in polycrystalline silicon investigated by atom probe tomography
    H. Takamizawa, Y. Shimizu, K. Inoue, Y. Nozawa, T. Toyama, F. Yano, M. Inoue, A. Nishida, and Y. Nagai
    Applied Physics Express, Vol. 9, No. 10, 106601 (2016) (4 pages).
    
    
    The effect of P or B predoping on As diffusion in polycrystalline Si was investigated by atom probe tomography. In all samples, a high concentration of As was found at grain boundaries, indicating that such boundaries are the main diffusion path. However, As grain-boundary diffusion was suppressed in the B-doped sample and enhanced in the P-doped sample. In a sample codoped with both P and B, As diffusion was somewhat enhanced, indicating competition between the effects of the two dopants. The results suggest that As grain-boundary diffusion can be controlled by varying the local concentration of P or B.
    
    
23. Quantitative analysis of hydrogen in SiO₂/SiN/SiO₂ stacks using atom probe tomography
    Y. Kunimune, Y. Shimada, Y. Sakurai, M. Inoue, A. Nishida, B. Han, Y. Tu, H. Takamizawa, Y. Shimizu, K. Inoue, F. Yano, Y. Nagai, T. Katayama, and T. Ide
    AIP Advances, Vol. 6, Issue 4, 045121 (2016) (7 pages).
    
    
    We have demonstrated that it is possible to reproducibly quantify hydrogen concentration in the SiN layer of a SiO₂/SiN/SiO₂ (ONO) stack structure using ultraviolet laser-assisted atom probe tomography (APT). The concentration of hydrogen atoms detected using APT increased gradually during the analysis, which could be explained by the effect of hydrogen adsorption from residual gas in the vacuum chamber onto the specimen surface. The amount of adsorbed hydrogen in the SiN layer was estimated by analyzing another SiN layer with an extremely low hydrogen concentration (<0.2 at.%). Thus, by subtracting the concentration of adsorbed hydrogen, the actual hydrogen concentration in the SiN layer was quantified as approximately 1.0 at.%. This result was consistent with that obtained by elastic recoil detection analysis (ERDA), which confirmed the accuracy of the APT quantification. The present results indicate that APT enables the imaging of the three-dimensional distribution of hydrogen atoms in actual devices at a sub-nanometer scale.
    
    
24. Suppression of segregation of the phosphorus δ-doping layer in germanium by incorporation of carbon
    M. Yamada, K. Sawano, M. Uematsu, Y. Shimizu, K. Inoue, Y. Nagai, and K. M. Itoh
    Japanese Journal of Applied Physics, Vol. 55, No. 3, 031304 (2016) (5 pages).
    
    
    The successful formation of abrupt phosphorus (P) δ-doping profiles in germanium (Ge) is reported. When the P δ-doping layers were grown by molecular beam epitaxy (MBE) directly on Ge wafers whose surfaces had residual carbon impurities, more than a half the phosphorus atoms were confined successfully within a few nm of the initial doping position even after the growth of Ge capping layers on the top. On the other hand, the same P layers grown on Ge buffer layers that had much less carbon showed significantly broadened P concentration profiles. Current-voltage characteristics of Au/Ti/Ge capping/P δ-doping/n-Ge structures having the abrupt P δ-doping layers with carbon assistance showed excellent ohmic behaviors when P doses were higher than 1×10¹⁴ cm^-2 and the capping layer thickness was as thin as 5 nm. Therefore, the insertion of carbon around the P doping layer is a useful way of realizing ultrashallow junctions in Ge.
    
    
25. Impact of carbon co-implantation on boron distribution and activation in silicon studied by atom probe tomography and spreading resistance measurements
    Y. Shimizu, H. Takamizawa, K. Inoue, F. Yano, S. Kudo, A. Nishida, T. Toyama, and Y. Nagai
    Japanese Journal of Applied Physics, Vol. 55, No. 2, 026501 (2016) (5 pages).
    
    
    The impact of carbon (C) co-implantation on boron (B) activation in crystalline silicon was investigated. The detailed distribution of B and C atoms and B activation ratios dependent on the C ion-implantation energies were examined based on three-dimensional spatial mappings of B and C obtained by atom probe tomography and from depth profiles of their concentrations from secondary ion mass spectrometry and depth profiles of carrier concentrations with spreading resistance measurements. At all C implantation energies (8, 15, and 30 keV), B out-diffusion during activation annealing was reduced, so that more B atoms were observed in the C co-implanted samples. The carrier concentration was decreased throughout the entire implanted region for C implantation energies of 15 and 30 keV, although it was only increased at greater depths for C co-implantation at 8 keV. Two different effects of C co-implantation, (I) reduction of B out-diffusion and (II) influence of B activation, were confirmed.
    
    
26. Evolution of shape, size, and areal density of a single plane of Si nanocrystals embedded in SiO₂ matrix studied by atom probe tomography
    B. Han, Y. Shimizu, G. Seguini, E. Arduca, C. Castro, G. Ben Assayag, K. Inoue, Y. Nagai, S. Schamm-Chardon, and M. Perego
    RSC Advances, Vol. 6, Issue 5, pp. 3617-3622 (2016).
    
    
    Single planes of Si nanocrystals (NCs) embedded in a SiO₂ matrix were synthesized by annealing SiO₂/SiO/SiO₂ multilayer structures deposited on Si (100) substrates by e-beam evaporation. The dependence of the shape, size, and areal density of Si NCs on the thickness of the initial SiO layer was investigated using atom probe tomography and validated by energy filtered transmission electron microscopy. Three kinds of samples were prepared with SiO layer thicknesses of 4, 6, and 10 nm. The size of Si NCs enlarged with increasing SiO layer thickness. The shape of Si NCs was mainly extended spheroid in all three kinds of samples. In the sample with the 4 nm-thick SiO layer, the Si NCs were more prolate than those in the other two samples. Moreover, many rod-shaped Si NCs appeared in the sample with the 10 nm-thick SiO layer. These rod-shaped Si NCs were found to be connected by small Si NCs. The areal densities of Si NCs were in the order of 10¹² NCs per cm² in all samples.
    
    
    

    - 2015 -

    
    
27. Elemental distributions in multilayer systems by laser-assisted atom probe tomography with various analysis directions
    M. Kubota, H. Takamizawa, Y. Shimizu, Y. Nozawa, N. Ebisawa, T. Toyama, Y. Ishida, K. Yanagiuchi, K. Inoue, and Y. Nagai
    Microscopy and Microanalysis, Vol. 21, Issue 6, pp. 1373-1378 (2015).
    
    
28. Characterization and process development of CVD/ALD‐based Cu(Mn)/Co(W) interconnect system
    K. Shima, Y. Tu, B. Han, H. Takamizawa, H. Shimizu, Y. Shimizu, T. Momose, K. Inoue, Y. Nagai, and Y. Shimogaki
    Proceedings of Advanced Metallization Conference (AMC) 2015 [Open Access], ISBN 978‐3‐944640‐97‐6
    
    
29. Diffusivity and solubility of Cu in a reactor pressure vessel studied by atom probe tomography
    M. Shimodaira, T. Toyama, F. Takahama, N. Ebisawa, Y. Nozawa, Y. Shimizu, K. Inoue, and Y. Nagai
    Materials Transactions, Vol. 56, No. 9, pp. 1513-1516 (2015).
    
    
30. Phosphorus and boron diffusion paths in the polycrystalline silicon gate of a trench-type three-dimensional metal-oxide-semiconductor field-effect transistor investigated by atom probe tomography
    B. Han, H. Takamizawa, Y. Shimizu, K. Inoue, Y. Nagai, F. Yano, Y. Kunimune, M. Inoue, and A. Nishida
    Applied Physics Letters, Vol. 107, Issue 2, 023506 (2015) (4 pages).
    
    
31. Three-dimensional evaluation of gettering ability for oxygen atoms at small-angle tilt boundaries in Czochralski-grown silicon crystals
    Y. Ohno, K. Inoue, K. Fujiwara, M. Deura, K. Kutsukake, I. Yonenaga, Y. Shimizu, K. Inoue, N. Ebisawa, and Y. Nagai
    Applied Physics Letters, Vol. 106, Issue 25, 251603 (2015) (4 pages).
    
    
32. Nanoscopic mechanism of Cu precipitation at small-angle tilt boundaries in Si
    Y. Ohno, K. Inoue, K. Kutsukake, M. Deura, T. Ohsawa, I. Yonenaga, H. Yoshida, S. Takeda, R. Taniguchi, H. Otubo, S. R. Nishitani, N. Ebisawa, Y. Shimizu, H. Takamizawa, K. Inoue, and Y. Nagai
    Physical Review B, Vol. 91, Issue 23, 235315 (2015) (5 pages).
    
    
33. Microstructural evolution of RPV steels under proton and ion irradiation studied by positron beam spectroscopy
    J. Jiang, Y. C. Wu, X. B. Liu, R. S. Wang, Y. Nagai, K. Inoue, Y. Shimizu, and T. Toyama
    Journal of Nuclear Materials, Vol. 458, pp. 326-334 (2015).
    
    
    

    - 2014 -

    
    
34. Role of W and Mn for reliable 1X nanometer-node ultra-large-scale integration Cu interconnects proved by atom probe tomography
    K. Shima, Y. Tu, H. Takamizawa, H. Shimizu, Y. Shimizu, T. Momose, K. Inoue, Y. Nagai, and Y. Shimogaki
    Applied Physics Letters, Vol. 105, Issue 13, 133512 (2014) (5 pages).
    
    
35. The diffusivity and solubility of copper in ferromagnetic-iron at lower temperatures studied by atom probe tomography
    T. Toyama, F. Takahama, A. Kuramoto, H. Takamizawa, Y. Nozawa, N. Ebisawa, M. Shimodaira, Y. Shimizu, K. Inoue, and Y. Nagai
    Scripta Materialia, Vol. 83, pp. 5-8 (2014).
    
    
36. Effects of post-irradiation annealing and re-irradiation on microstructure in surveillance test specimens of the Loviisa-1 reactor studied by atom probe tomography and positron annihilation
    T. Toyama, A. Kuramoto, Y. Nagai, K. Inoue, Y. Nozawa, Y. Shimizu, Y. Matsukawa, M. Hasegawa, and M. Valo
    Journal of Nuclear Materials, Vol. 449, Issues 1-3, pp. 207-212 (2014).
    
    
37. Depth analysis of Ta/NiFe/Ta/CoFeB/Ta/NiFe multilayer thin films: Comparison of atom probe tomography and Auger electron spectroscopy
    M. Kubota, Y. Ishida, K. Yanagiuchi, H. Takamizawa, Y. Nozawa, N. Ebisawa, Y. Shimizu, T. Toyama, K. Inoue, and Y. Nagai
    Journal of Surface Analysis, Vol. 20, No. 3, pp. 207-210 (2014).
    
    
38. Behavior of phosphorous and contaminants from monolayer doping combined with a conventional spike annealing method
    Y. Shimizu, H. Takamizawa, K. Inoue, F. Yano, Y. Nagai, L. Lamagna, G. Mazzeo, M. Perego, and E. Prati
    Nanoscale, Vol. 6, Issue 2, pp. 706-710 (2014).
    
    
    

    - 2013 -

    
    
39. New applications in atom probe tomography
    D. J. Larson, J. W. Valley, T. Ushikubo, M. K. Miller, H. Takamizawa, Y. Shimizu, L. M. Gordon, D. Joester, A. D. Giddings, D. A. Reinhard, T. J. Prosa, D. P. Olson, D. F. Lawrence, P. H. Clifton, R. M. Ulfig, I. Y. Martin, and T. F. Kelly
    Microscopy and Microanalysis, Vol. 19 (Supplement 2), pp. 1022-1023 (2013).
    
    
40. Three-dimensional evaluation of gettering ability of Σ3{111} grain boundaries in silicon by atom probe tomography combined with transmission electron microscopy
    Y. Ohno, K. Inoue, Y. Tokumoto, K. Kutsukake, I. Yonenaga, N. Ebisawa, H. Takamizawa, Y. Shimizu, K. Inoue, Y. Nagai, H. Yoshida, and S. Takeda
    Applied Physics Letters, Vol. 103, Issue 10, 102102 (2013) (4 pages).
    
    
41. Three-dimensional characterization of deuterium implanted in silicon using atom probe tomography
    H. Takamizawa, K. Hoshi, Y. Shimizu, F. Yano, K. Inoue, S. Nagata, T. Shikama, and Y. Nagai
    Applied Physics Express, Vol. 6, No. 6, 066602 (2013) (3 pages).
    
    
42. Three-dimensional dopant characterization in actual metal-oxide-semiconductor devices of 65 nm node by atom probe tomography
    K. Inoue, H. Takamizawa, Y. Shimizu, T. Toyama, F. Yano, A. Nishida, T. Mogami, K. Kitamoto, T. Miyagi, J. Kato, S. Akahori, N. Okada, M. Kato, H. Uchida, and Y. Nagai
    Applied Physics Express, Vol. 6, No. 4, 046502 (2013) (4 pages).
    
    
43. Atomic-scale characteriation of germanium isotopic multilayers by atom probe tomography
    Y. Shimizu, H. Takamizawa, Y. Kawamura, M. Uematsu, T. Toyama, K. Inoue, E. E. Haller, K. M. Itoh, and Y. Nagai
    Journal of Applied Physics, Vol. 113, Issue 2, 026101 (2013) (3 pages).
    
    
44. 陽電子消滅および3次元アトムプローブによる原子炉圧力容器鋼の照射脆化機構に関する研究 -フィンランド・ロビーザ炉監視試験片を例として-
    外山健, 蔵本明, 野沢康子, Matti Valo, 清水康雄, 井上耕治, 長谷川雅幸, 永井康介
    日本陽電子科学会会報 陽電子科学 「最近の研究から」 第1号（通算 第5巻, 第2号）, pp. 41-46 (2013).
    
    
45. ３次元アトムプローブによる半導体ナノ構造の元素分布解析
    清水康雄, 井上耕治, 高見澤悠, 矢野史子, 永井康介
    日本真空学会（Journal of the Vacuum Society of Japan）誌 解説
    第56巻, 第9号, pp. 340-347 (2013).
    
    
    

    - 2012 -

    
    
46. Correlation between threshold voltage and channel boron concentration in silicon-based negative-type metal-oxide-semiconductor field-effect transistors studied by atom probe tomography
    H. Takamizawa, Y. Shimizu, K. Inoue, T. Toyama, F. Yano, A. Nishida, T. Mogami, N. Okada, M. Kato, H. Uchida, K. Kitamoto, T. Miyagi, J. Kato, and Y. Nagai
    Applied Physics Letters, Vol. 100, Issue 25, 253504 (2012) (3 pages).
    
    
47. Dopant characterization in self-regulatory plasma doped fin field-effect transistors by atom probe tomography
    H. Takamizawa, Y. Shimizu, Y. Nozawa, T. Toyama, H. Morita, Y. Yabuuchi, M. Ogura, and Y. Nagai
    Applied Physics Letters, Vol. 100, Issue 9, 093502 (2012) (3 pages).
    
    
48. Investigation of the factors determining the SIMS depth resolution function in silicon-isotope multiple layers
    M. Tomita, K. Koike, H. Akutsu, S. Takeno, Y. Kawamura, Y. Shimizu, M. Uematsu, and K. M. Itoh
    Journal of Vacuum Science & Technology B, Vol. 30, Issue 1, 011803 (2012) (12 pages).
    
    
49. レーザー３次元アトムプローブによる半導体材料中のドーパント分布解析
    井上耕治, 清水康雄, 高見澤悠
    日本物理学会誌「最近の研究から」 第67巻, 第9号, pp. 645-649 (2012).
    
    
    

    - 2011 -

    
    
50. Three-dimensional elemental analysis of commercial 45 nm node device with high-k / metal gate by atom probe tomography
    K. Inoue, H. Takamizawa, K. Kitamoto, J. Kato, T. Miyagi, Y. Nakagawa, N. Kawasaki, N. Sugiyama, H. Hashimoto, Y. Shimizu, T. Toyama, Y. Nagai, and A. Karen
    Applied Physics Express, Vol. 4, No. 11, 116601 (2011) (3 pages).
    
    
51. Origin of characteristic variability in metal-oxide-semiconductor field-effect transistors revealed by three-dimensional atom imaging
    H. Takamizawa, Y. Shimizu, K. Inoue, T. Toyama, N. Okada, M. Kato, H. Uchida, F. Yano, A. Nishida, T. Mogami, and Y. Nagai
    Applied Physics Letters, Vol. 99, Issue 13, 133502 (2011) (3 pages).
    
    
52. Impact of carbon coimplantation on boron behavior in silicon: Carbon-boron coclustering and suppression of boron diffusion
    Y. Shimizu, H. Takamizawa, K. Inoue, T. Toyama, Y. Nagai, N. Okada, M. Kato, H. Uchida, F. Yano, T. Tsunomura, A. Nishida, and T. Mogami
    Applied Physics Letters, Vol. 98, Issue 23, 232101 (2011) (3 pages).
    
    
53. Channel dopant distribution in metal-oxide-semiconductor field-effect transistors analyzed by laser-assisted atom probe tomography
    H. Takamizawa, K. Inoue, Y. Shimizu, T. Toyama, F. Yano, T. Tsunomura, A. Nishida, T. Mogami, and Y. Nagai
    Applied Physics Express, Vol. 4, No. 3, 036601 (2011) (3 pages).
    
    
54. Depth and lateral resolution of laser-assisted atom probe microscopy of silicon revealed by isotopic heterostructures
    Y. Shimizu, Y. Kawamura, M. Uematsu, M. Tomita, T. Kinno, N. Okada, M. Kato, H. Uchida, M. Takahashi, H. Ito, H. Ishikawa, Y. Ohji, H. Takamizawa, Y. Nagai, and K. M. Itoh
    Journal of Applied Physics, Vol. 109, Issue 3, 036102 (2011) (3 pages).
    
    
    

    - 2010 -

    
    
55. Critical displacement of host-atoms for amorphization in germanium induced by arsenic implantation
    Y. Kawamura, Y. Shimizu, H. Oshikawa, M. Uematsu, E. E. Haller, and K. M. Itoh
    Applied Physics Express, Vol. 3, No. 7, 071303 (2010) (3 pages).
    
    
    

    - 2009 -

    
    
56. Quantitative evaluation of germanium displacement induced by arsenic implantation using germanium isotope superlattices
    Y. Kawamura, Y. Shimizu, H. Oshikawa, M. Uematsu, E. E. Haller, and K. M. Itoh
    Physica B: Condensed Matter, Vol. 404, Issues 23-24, pp. 4546-4548 (2009).
    
    
57. Atom probe microscopy of three-dimensional distribution of silicon isotopes in ²⁸Si/³⁰Si isotope superlattices with sub-nanometer spatial resolution
    Y. Shimizu, Y. Kawamura, M. Uematsu, K. M. Itoh, M. Tomita, M. Sasaki, H. Uchida, and M. Takahashi
    Journal of Applied Physics, Vol. 106, Issue 7, 076102 (2009) (3 pages).
    
    
58. Probing the behaviors of point defects in silicon and germanium using isotope superlattices
    M. Uematsu, M. Naganawa, Y. Shimizu, K. M. Itoh, K. Sawano, Y. Shiraki, and E. E. Haller
    ECS Transactions, Vol. 25, Issue 3, pp. 51-54 (2009).
    
59. Behaviors of neutral and charged silicon self-interstitials during transient enhanced diffusion in silicon investigated by isotope superlattices
    Y. Shimizu, M. Uematsu, K. M. Itoh, A. Takano, K. Sawano, and Y. Shiraki
    Journal of Applied Physics, Vol. 105, Issue 1, 013504 (2009) (6 pages).
    
    
    

    - 2008 -

    
    
60. Silicon isotope superlattices: Ideal SIMS standards for shallow junction characterization
    Y. Shimizu, A. Takano, and K. M. Itoh
    Applied Surface Science, Vol. 255, Issue 4, pp. 1345-1347 (2008).
    
    
61. Film thickness determinating method of the silicon isotope superlattices by SIMS
    A. Takano, Y. Shimizu, and K. M. Itoh
    Applied Surface Science, Vol. 255, Issue 4, pp. 1430-1432 (2008).
    
    
62. Charge states of vacancies in germanium investigated by simultaneous observation of germanium self- and arsenic diffusion
    M. Naganawa, Y. Shimizu, M. Uematsu, K. M. Itoh, K. Sawano, Y. Shiraki, and E. E. Haller
    Applied Physics Letters, Vol. 93, Issue 19, 191905 (2008) (3 pages).
    
    
63. Accurate determination of the intrinsic diffusivities of boron, phosphorus, and arsenic in silicon: The influence of SiO₂ films
    M. Naganawa, Y. Kawamura, Y. Shimizu, M. Uematsu, K. M. Itoh, H. Ito, M. Nakamura, H. Ishikawa, and Y. Ohji
    Japanese Journal of Applied Physics, Vol. 47, No. 8R, pp. 6205-6207 (2008).
    
    
64. Quantitative evaluation of silicon displacement induced by arsenic implantation using silicon isotope superlattices
    Y. Shimizu, M. Uematsu, K. M. Itoh, A. Takano, K. Sawano, and Y. Shiraki
    Applied Physics Express, Vol. 1, No. 2, 021401 (2008) (3 pages).
    
    
    

    - 2007 -

    
    
65. Simultaneous observation of the behavior of impurities and silicon atoms in silicon isotope superlattices
    Y. Shimizu, A. Takano, M. Uemtasu, and K. M. Itoh
    Physica B: Condensed Matter, Vols. 401-402, pp. 597-599 (2007).
    
    
66. Defect studies for the development of nano-scale silicon diffusion simulators
    M. Uematsu, Y. Shimizu, and K. M. Itoh
    Physica B: Condensed Matter, Vols. 401-402, pp. 511-518 (2007).
    
    
67. Experimental evidence of the vacancy-mediated silicon self-diffusion in single-crystalline silicon
    Y. Shimizu, M. Uematsu, and K. M. Itoh
    Physical Review Letters, Vol. 98, Issue 9, 095901 (2007) (4 pages).
    
    
68. Self-diffusion of Si at low temperatures revealed by annealing and Raman spectroscopy of Si isotope superlattices
    Y. Shimizu and K. M. Itoh
    AIP Conference Proceedings, 28th International Conference on the Physics of Semiconductors, Vol. 893, pp. 205-206 (2007).
    
    
    

    - 2006 -

    
    
69. Observation of Si emission during thermal oxidation of Si(001) with high-resolution RBS
    S. Hosoi, K. Nakajima, M. Suzuki, K. Kimura, Y. Shimizu, S. Fukatsu, K. M. Itoh, M. Uematsu, H. Kageshima, and K. Shiraishi
    Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Vol. 249, Issues 1-2, pp. 390-393 (2006).
    
    
70. Growth and characterization of short-period silicon isotope superlattices
    Y. Shimizu and K. M. Itoh
    Thin Solid Films, Vol. 508, Issues 1-2, pp. 160-162 (2006).
    
    

● 著 書 ●

1. 試料分析講座 半導体・電子材料分析
   井上耕治, 清水康雄, 永井康介（第6章 三次元アトムプローブ（pp. 71-92））
   ISBN 978-4-621-08700-8, 日本分析化学会編, 丸善出版, 2013年7月刊行

● 知 的 財 産 権 ●

1. 半導体装置およびその製造方法
   特開2012-238760
   西田彰男, 矢野史子, 永井康介, 清水康雄, 高見澤悠


2. イオン照射効果評価方法，プロセスシミュレータ及びデバイスシミュレータ
   特許第5004072号
   伊藤公平, 清水康雄