1997 Fiscal Year Annual Research Report

スピン偏極電子トンネル型大容量・高速ランダムアクセスメモリー

Research Project

Project/Area Number	09305024
Research Category	Grant-in-Aid for Scientific Research (A)
Research Institution	Tokyo Institute of Technology
Principal Investigator	直江正彦東京工業大学, 工学部, 教授 (40016465)
Co-Investigator(Kenkyū-buntansha)	松下伸広東京工業大学, 工学部, 助手 (90229469) 金田久美子東京工業大学, 工学部, 助手 (10108227) 中川茂樹東京工業大学, 工学部, 助教授 (60180246)
Keywords	スピン偏極電子 / スピンバルブ / トンネル効果 / 不揮発性メモリー / Si_3N_4絶縁層 / 反強磁性層 / 交換バイアス磁界
Research Abstract	本研究ではスピン偏極電子トンネル型のスピンバルブ素子の作製法を確立し、これを大容量で超高速の不揮発性ランダムアクセスメモリーへ応用することを目指している。本年度はトンネル型スピンバルブ素子の中間絶縁層としてSi_3N_4窒化物絶縁膜を提案しロセスの再現性、素子動作の安定性、高性能化を目指した。また、交換バイアス磁界印加のための反強磁性層の作製条件の最適化を行った。 (1)強磁性層および中間絶縁層の作製条件の最適化二枚の強磁性層(NiFe層)と極薄絶縁層によるサンドイッチ構造は、本メモリー素子の基本構造となる。中間絶縁層としてはこれまで極薄Al膜の自然酸化膜などが用いられてきたが、信頼性・再現性の低下を招くと考えられる。本研究ではSi_3N_4窒化物膜を中間絶縁層として採用することを試みた。トンネル電流は膜面垂直方向の電流を測定することになるため、フォトリソグラフィー技術を用いて測定用デバイスの試作を行った。この結果、膜の垂直方向への電流-電圧特性を測定することで、約1nmのSi_3N_4膜がトンネル障壁を有する絶縁層として機能していることが確かめられた。 (2)反強磁性層の最適化交換バイアスによりフリー層の磁化をピン止めするためには、反強磁性層の作製条件の最適化が必要である。反強磁性層としてはFeMn層を用いた。Ni-Fe層上にFeMn層を堆積して交換バイアス印加を実現するためには、γ-FeMnの(111)配向膜を得る必要があるが、このためにはNi-Fe層の(111)配向を向上させることが必要となる。Si_3N_4膜上では良好な(111)面配向は得られなかったが、Siスパッタ膜上では良好な(111)配向膜が得られることを見出した。そこで1nmのSi_3N_4膜と0.5nmの極薄のSi層と組み合わせた絶縁層を採用することで上部に堆積するNi-Fe層の(111)面配向を促進し、さらにその上部に堆積されるFe-Mn反強磁性層の(111)面配向を促進され、100Oe程度の大きな交換バイアス磁界が再現性良く得られることを見出した。また、このような構造を持つデバイスの試作を行い、交換バイアスとトンネル電流が同時に観測されていることが確認できた。

Research Products

(29 results)

All Other

All Publications (29 results)

[Publications] S.Nakagawa: "Preparation of Soft Magnetic and Thermally stable Fe-Co-Ta:N/Ti mulilayered films by sputter deposition" Journal of Applied Physics. 81[8]. 3782-3784 (1997)
[Publications] K.Noma: "Effects of composition control on crystallographic and magnetic characteristics of Ba ferrite films sputtered with the mixture of Xe, Kr, Ar and O_2 for recording media" Journal of Applied Physics. 81[8]. 4377-4379 (1997)
[Publications] Takayuki Ichihara: "Improvement of micromagnetism of Ni-Fe/Co67Cr33 multilayers for backlayers of perpendicular magnetic recording media" IEEE Trans. on Magn.33,[5]. 3004-3006 (1997)
[Publications] Shigeki Nakagawa: "Distribution of Coercivity and Anisotropy through Thickness Direction in Sputtered Co-Cr Films and its Relationship to Noise Characteristics in Perpendicular Magnetic Recording." IEEE Trans. on Magn.33,[5]. 3091-3093 (1997)
[Publications] Yasuyoshi Miyamoto: "MR characteristics of Ni_<81>Fe_<19>/Cu multilayers deposited by Kr sputtering with Ar ion bombardment on interfaces" IEEE Trans. on Magn.33,[5]. 3523-3525 (1997)
[Publications] K.Noma: "Study on S-and R-block construction with additional spinel blocks in sputter deposited Ba ferrite films" IEEE Trans. on Magn.33,[5]. 3637-3639 (1997)
[Publications] Shigeki Nakagawa: "Improvement of Soft Magnetic Properties of Ferro Magnetic Fe-Co-Ta:N/M Films Multilayered with Paramagnetic Ti, Co_<67>Cr_<33> and Fe_<82>Co_9Ta_9:N Interlayers" IEEE Trans. on Magn.33,[5]. 3805-3807 (1997)
[Publications] N.Matsushita: "Ferromagnetic Characteristics of a Perovskite Type of (La, Sr) MnO_3 Films Deposited by Kr Sputtering," Proc. of 7th International Conference on Ferrites (ICF 7). 629-630 (1997)
[Publications] K.Noma: "Increase of Saturation Magneization of Ba Ferrite Films Deposited by Adding Xe into Sputtering Gas Mixture" Proc. of 7th International Conference on Ferrites (ICF 7). 487-488 (1997)
[Publications] M.Naoe: "Sputter Deposition of Ferrite Films and Application for High Density Rigid Disk Media in Contact Mode" Proc. of 7th International Conference on Ferrites (ICF 7). 735-738 (1997)
[Publications] M.Naoe: "″Crystallographic and Magnetic Characteristics of Ba Ferrite Sputtered Films for High Density Magnetic Recording Disks" Proc. of 7th International Conference on Ferrites (ICF 7). 749-750 (1997)
[Publications] T.Ichihara: "Preparation of Very Soft Magnetic Ni-Fe/Co_<67>Cr_<33> Multilayers by Facing Targets Sputtering with External Magnetic Field" Proc. of 4^<th> Inter. Symp. on Sputtering and Plasma Processing (ISSP′97). 111-116 (1997)
[Publications] N.Matsushita: "Diagnosis of Mixture Gas Discharge in Damage-Free Sputtering Apparatus and Deposition of Ba Ferrite Films at Low Substrate Temperature" Proc. of 4^<th> Inter. Symp. on Sputtering and Plasma Processing (ISSP′97). 117-122 (1997)
[Publications] Y.Miyamoto: "Giant Magnetoresistance of Ni_<81>Fe_<19>/Cu Multilayers Deposited by Dual Ion Beam Sputtering" Proc. of 4^<th> Inter. Symp. on Sputtering and Plasma Processing (ISSP′97). 123-128 (1997)
[Publications] S.Nakagawa: "Control of Nano-Structure of the Initial Growth Layers of Co-Cr Thin Films Deposited by Facing Targets Sputtering" Proc. of 4^<th> Inter. Symp. on Sputtering and Plasma Processing (ISSP′97). 151-156 (1997)
[Publications] Y.Miyamoto: "Effects of Ion Bombardment to Interfaces on Residual Internal Stress and Crystalline Structures on Multilayered Films" Proc. of 4^<th> Inter. Symp. on Sputtering and Plasma Processing (ISSP′97). 245-250 (1997)
[Publications] T.Ichihara: "Analysis of Stray Magnetic Field at The Substrate and Effect of Applying External Magnetic Field in Facing Targets Sputtering" Proc. of 4^<th> Inter. Symp. on Sputtering and Plasma Processing (ISSP′97). 251-256 (1997)
[Publications] M.Naoe: "Ion Beam Deposition Method Using Facing Targets Sputtering Ion Source As a New Reactive Deposition Method" Proc. of 4^<th> Inter. Symp. on Sputtering and Plasma Processing (ISSP′97). 411-420 (1997)
[Publications] 中川茂樹: "Co-Cr薄膜の保磁力と磁気異方性の膜厚方向分布と記録再生特性" 日本応用磁気学会誌. 21,[S1]. 29-33 (1997)
[Publications] 松下伸広: "酸化物磁性薄膜による等方性磁気ディスクの作製と記録再生特性" 日本応用磁気学会誌. 21,[S1]. 34-37 (1997)
[Publications] 市原貴幸: "磁界印加堆積法によるNi-Fe/Co_<67>Cr_<33>多層膜の透磁率向上" 日本応用磁気学会誌. 21,[4-2]. 485-488 (1997)
[Publications] 宮本泰敬: "Ni-Fe/Cu多層膜における界面へのイオン照射" 日本応用磁気学会誌. 21,[4-2]. 565-568 (1997)
[Publications] 中川茂樹: "垂直磁気記録媒体・ヘッド用軟磁性層の特性改善" 日本応用磁気学会誌. 21,[6]. 983-988 (1997)
[Publications] Tomoyosi Siosawa: "Crystallographic and Magnetic Characteristics of c-axis Oriented Ba Ferrite Layer Deposited on Pt(111) Underlayer" Journal of Magnetics Society of Japan. 21,[S2]. 73-76 (1997)
[Publications] Kentaro Watanabe: "Investigation of the Exchange Coupling Field between Ni_<81>Fe_<19>/Fe_<50>Mn_<50> Bilayers in Spin Valve Devices by Ion Bombardment to Interfaces" Journal of Magnetics Society of Japan. 21,[S2]. 379-382 (1997)
[Publications] Masaru Hatakeyama: "Effect of Paramagnetic Co_<67>Cr_<33> Intermediate Layer on Longitudinal Recording Media with Ferromagnetic Co_<83>Cr_<17>/Cr Bilayered Film" Journal of Magnetics Society of Japan. 21,[S2]. 537-540 (1997)
[Publications] Hiroaki Matsumiya: "Preparation of Soft Magnetic Films of Nanocrystalline Fe-Cu-Nb-Si-B Alloy for Low Noise Backlayers" Journal of Magnetics Society of Japan. 21,[S2]. 549-552 (1997)
[Publications] Y.Kitamoto: "Sputter-Deposition of Co-Cr-Ta Alloy Layers on Ni-Zn Ferrite Plated Underlayers" IEEE Trans. on Magn.33,[5]. 3085-3087 (1997)
[Publications] Y.Kitamoto: "Compact Sputtering Apparatus for Depositing Co-Cr Alloy Thin Films in Magnetic Disks" Proc. of 4^<th> Inter. Symp. on Sputtering and Plasma Processing (ISSP′97). 519-522 (1997)

1997 Fiscal Year Annual Research Report

スピン偏極電子トンネル型大容量・高速ランダムアクセスメモリー

Principal Investigator

直江 正彦 東京工業大学, 工学部, 教授 (40016465)

Research Products

[Publications] S.Nakagawa: "Preparation of Soft Magnetic and Thermally stable Fe-Co-Ta:N/Ti mulilayered films by sputter deposition" Journal of Applied Physics. 81[8]. 3782-3784 (1997)

[Publications] K.Noma: "Effects of composition control on crystallographic and magnetic characteristics of Ba ferrite films sputtered with the mixture of Xe, Kr, Ar and O_2 for recording media" Journal of Applied Physics. 81[8]. 4377-4379 (1997)

[Publications] Takayuki Ichihara: "Improvement of micromagnetism of Ni-Fe/Co67Cr33 multilayers for backlayers of perpendicular magnetic recording media" IEEE Trans. on Magn.33,[5]. 3004-3006 (1997)

[Publications] Shigeki Nakagawa: "Distribution of Coercivity and Anisotropy through Thickness Direction in Sputtered Co-Cr Films and its Relationship to Noise Characteristics in Perpendicular Magnetic Recording." IEEE Trans. on Magn.33,[5]. 3091-3093 (1997)

[Publications] Yasuyoshi Miyamoto: "MR characteristics of Ni_<81>Fe_<19>/Cu multilayers deposited by Kr sputtering with Ar ion bombardment on interfaces" IEEE Trans. on Magn.33,[5]. 3523-3525 (1997)

[Publications] K.Noma: "Study on S-and R-block construction with additional spinel blocks in sputter deposited Ba ferrite films" IEEE Trans. on Magn.33,[5]. 3637-3639 (1997)

[Publications] Shigeki Nakagawa: "Improvement of Soft Magnetic Properties of Ferro Magnetic Fe-Co-Ta:N/M Films Multilayered with Paramagnetic Ti, Co_<67>Cr_<33> and Fe_<82>Co_9Ta_9:N Interlayers" IEEE Trans. on Magn.33,[5]. 3805-3807 (1997)

[Publications] N.Matsushita: "Ferromagnetic Characteristics of a Perovskite Type of (La, Sr) MnO_3 Films Deposited by Kr Sputtering," Proc. of 7th International Conference on Ferrites (ICF 7). 629-630 (1997)

[Publications] K.Noma: "Increase of Saturation Magneization of Ba Ferrite Films Deposited by Adding Xe into Sputtering Gas Mixture" Proc. of 7th International Conference on Ferrites (ICF 7). 487-488 (1997)

[Publications] M.Naoe: "Sputter Deposition of Ferrite Films and Application for High Density Rigid Disk Media in Contact Mode" Proc. of 7th International Conference on Ferrites (ICF 7). 735-738 (1997)

[Publications] M.Naoe: "″Crystallographic and Magnetic Characteristics of Ba Ferrite Sputtered Films for High Density Magnetic Recording Disks" Proc. of 7th International Conference on Ferrites (ICF 7). 749-750 (1997)

[Publications] T.Ichihara: "Preparation of Very Soft Magnetic Ni-Fe/Co_<67>Cr_<33> Multilayers by Facing Targets Sputtering with External Magnetic Field" Proc. of 4^<th> Inter. Symp. on Sputtering and Plasma Processing (ISSP′97). 111-116 (1997)

[Publications] N.Matsushita: "Diagnosis of Mixture Gas Discharge in Damage-Free Sputtering Apparatus and Deposition of Ba Ferrite Films at Low Substrate Temperature" Proc. of 4^<th> Inter. Symp. on Sputtering and Plasma Processing (ISSP′97). 117-122 (1997)

[Publications] Y.Miyamoto: "Giant Magnetoresistance of Ni_<81>Fe_<19>/Cu Multilayers Deposited by Dual Ion Beam Sputtering" Proc. of 4^<th> Inter. Symp. on Sputtering and Plasma Processing (ISSP′97). 123-128 (1997)

[Publications] S.Nakagawa: "Control of Nano-Structure of the Initial Growth Layers of Co-Cr Thin Films Deposited by Facing Targets Sputtering" Proc. of 4^<th> Inter. Symp. on Sputtering and Plasma Processing (ISSP′97). 151-156 (1997)

[Publications] Y.Miyamoto: "Effects of Ion Bombardment to Interfaces on Residual Internal Stress and Crystalline Structures on Multilayered Films" Proc. of 4^<th> Inter. Symp. on Sputtering and Plasma Processing (ISSP′97). 245-250 (1997)

[Publications] T.Ichihara: "Analysis of Stray Magnetic Field at The Substrate and Effect of Applying External Magnetic Field in Facing Targets Sputtering" Proc. of 4^<th> Inter. Symp. on Sputtering and Plasma Processing (ISSP′97). 251-256 (1997)

[Publications] M.Naoe: "Ion Beam Deposition Method Using Facing Targets Sputtering Ion Source As a New Reactive Deposition Method" Proc. of 4^<th> Inter. Symp. on Sputtering and Plasma Processing (ISSP′97). 411-420 (1997)

[Publications] 中川茂樹: "Co-Cr薄膜の保磁力と磁気異方性の膜厚方向分布と記録再生特性" 日本応用磁気学会誌. 21,[S1]. 29-33 (1997)

[Publications] 松下伸広: "酸化物磁性薄膜による等方性磁気ディスクの作製と記録再生特性" 日本応用磁気学会誌. 21,[S1]. 34-37 (1997)

[Publications] 市原貴幸: "磁界印加堆積法によるNi-Fe/Co_<67>Cr_<33>多層膜の透磁率向上" 日本応用磁気学会誌. 21,[4-2]. 485-488 (1997)

[Publications] 宮本泰敬: "Ni-Fe/Cu多層膜における界面へのイオン照射" 日本応用磁気学会誌. 21,[4-2]. 565-568 (1997)

[Publications] 中川茂樹: "垂直磁気記録媒体・ヘッド用軟磁性層の特性改善" 日本応用磁気学会誌. 21,[6]. 983-988 (1997)

[Publications] Tomoyosi Siosawa: "Crystallographic and Magnetic Characteristics of c-axis Oriented Ba Ferrite Layer Deposited on Pt(111) Underlayer" Journal of Magnetics Society of Japan. 21,[S2]. 73-76 (1997)

[Publications] Kentaro Watanabe: "Investigation of the Exchange Coupling Field between Ni_<81>Fe_<19>/Fe_<50>Mn_<50> Bilayers in Spin Valve Devices by Ion Bombardment to Interfaces" Journal of Magnetics Society of Japan. 21,[S2]. 379-382 (1997)

[Publications] Masaru Hatakeyama: "Effect of Paramagnetic Co_<67>Cr_<33> Intermediate Layer on Longitudinal Recording Media with Ferromagnetic Co_<83>Cr_<17>/Cr Bilayered Film" Journal of Magnetics Society of Japan. 21,[S2]. 537-540 (1997)

[Publications] Hiroaki Matsumiya: "Preparation of Soft Magnetic Films of Nanocrystalline Fe-Cu-Nb-Si-B Alloy for Low Noise Backlayers" Journal of Magnetics Society of Japan. 21,[S2]. 549-552 (1997)

[Publications] Y.Kitamoto: "Sputter-Deposition of Co-Cr-Ta Alloy Layers on Ni-Zn Ferrite Plated Underlayers" IEEE Trans. on Magn.33,[5]. 3085-3087 (1997)

[Publications] Y.Kitamoto: "Compact Sputtering Apparatus for Depositing Co-Cr Alloy Thin Films in Magnetic Disks" Proc. of 4^<th> Inter. Symp. on Sputtering and Plasma Processing (ISSP′97). 519-522 (1997)

直江正彦東京工業大学, 工学部, 教授 (40016465)