2003 Fiscal Year Annual Research Report

強誘電体薄膜の物性制御と次世代メモリデバイスへの応用

Research Project

Project/Area Number	12134205
Research Institution	Osaka University
Principal Investigator	奥山雅則大阪大学, 基礎工学研究科, 教授 (60029569)
Co-Investigator(Kenkyū-buntansha)	金島岳大阪大学, 基礎工学研究科, 助手 (30283732) 山下馨大阪大学, 基礎工学研究科, 助手 (40263230) 野田実大阪大学, 基礎工学研究科, 助教授 (20294168) 上野智雄東京農工大学, 工学部, 助教授 (90223487) 舟窪浩東京工業大学, 総合理工学研究科, 助教授 (90219080)
Keywords	強誘電体 / 先端機能デバイス / 電子・電気材料 / 表面・界面物性 / メモリデバイス
Research Abstract	Pulsed Laser Deposition(PLD)法により製膜したSrBi_2Ta_2O_9(SBT)薄膜を用いたMetal-Ferroelectric-Insulator-Semiconductor(MFIS)構造においてRapid Thermal Annealing(RTA)を行うことにより良好な静電容量保持特性が得られており、このゲート形成プロセスを用いたMFIS-FETを新たに考案し試作を行った。試作したp-Channel FETのId-Vg特性において強誘電体分極ヒステリシスによって制御されたId-Vgヒステリシスが観測され、メモリウインドウは約1.5Vであった。IdのON/OFF比はSBT強誘電体薄膜を形成する以前のMOSFETと同等の7桁以上と非常に良好な特性が得られた。データ保持時間は10^3秒以上が確認された。一方、さらなる特性の向上を目指し、強誘電体膜成長中の拡散バリアとなり良好な表面チャネルキャリア移動度を与えるI層として酸窒化膜を採用し、その最適化を行った。Si基板上に3種類の窒化膜:1)N_2O雰囲気中での熱酸窒化膜、2)Cat-CVD法による表面窒化酸化膜、3)Plasma CVDによる表面窒化酸化膜、を形成し1)SiON/Si,2),3)SiON/SiO_2/Si構造を作製し評価した。その結果、Cat-CVD法による酸窒化膜は表面に窒素が偏在し、拡散バリア性の向上、リーク電流のプールフレンケル成分の低減、等が見られた。また、Plasma窒化法による酸窒化膜は比較的膜内部にも窒素が含有され、膜全体としてバリア性も高いと考察された。また窒化時間により表面付近窒素含有量を制御できた。これら窒化膜をI層として用いる場合のMFIS-FETプロセスフローも提案、検討した。さらに前年度から強誘電体-絶縁体界面伝導電流を利用した新構造ゲートFETメモリの提案、検討を進めており、強誘電体分極ヒステリシスに対応するId-Vgヒステリシス特性、IdのON/OFF比約2桁が得られた。本構造はSi以外の基板への応用が可能でありPt金属上でのヒステリシスも確認されている。

Research Products

(12 results)

All Other

All Publications (12 results)

[Publications] A.Shibuya etc.: "Natural-Superlattice-Structured Ferroelectric Bi_4Ti_3O_<12>-SrBi_4Ti_4O_<15> Thin Films Prepared by Pulsed Laser Deposition"Japanese Journal of Applied Physics. 42. 5986-5989 (2003)
[Publications] K.Y.Yun etc.: "Prominent ferroelectricity of BiFeO_3 thin films prepared by pulsed-laser deposition"Applied Physics Letters. 83. 3981-3983 (2003)
[Publications] M.Takahashi etc.: "Photoelectron Spectroscopic Studies of Bismuth-Excess Strontium Bismuth Tantalate Thin Films and their High-Pressure-O_2-Annealing Effects"Journal of Applied Physics. 94. 6729-6734 (2003)
[Publications] M.Takahashi etc.: "Photoyield and x-ray-photoelectron spectroscopic studies of O_2-annealing effects on SrBi_2Ta_2O_9 thin films prepared by pulsed laser deposition"Journal of Applied Physics. 94. 1912-1917 (2003)
[Publications] A.Shibuya etc.: "Preparation and basic properties of ferroelectric thin films having a superlattice structure of 2 Bi_3TiNbO_9 units-1 Bi_4Ti_3O_<12> unit"Applied Physics Letters. 83. 1411-1413 (2003)
[Publications] Z.Wei etc.: "A Very Low-Temperature Growth of BaTiO_3 Thin Film by Hydrothermal Treatment Following Sol-Gel Coating at 200 Degree Celsius"Integrated Ferroelectrics. 52. 111-118 (2003)
[Publications] Kwi-Young Yun etc.: "Effects of Annealing Atmosphere on Crystallization and Electrical Properties in BiFeO_3 Thin Films by Chemical Solution Deposition(CSD)"Journal of The Korean Physical Society. 42. S1153-S1156 (2003)
[Publications] M.Takahashi etc.: "X-ray Photoelectron and UV Photoyield Spectroscopy on Sr_xBi_yTa_2O_9 Films"Journal of The Korean Physical Society. 42. S1399-S1403 (2003)
[Publications] A.Shibuya etc.: "Oxygen Annealing Effects in Natural-Superlattice-Structured Bi_4Ti_3O_<12>-SrBi_4Ti_4O_<15> Ferroelectric Thin Films"Journal of The Korean Physical Society. 42. S1339-S1342 (2003)
[Publications] K.Saito etc.: "Structural characterization and 90° domain contribution to ferroelectricity of epitaxial Pb(Zr_<0.35>,Ti_<0.65>)O_3 thin films"Journal of Applied Physics. 93(1). 545-550 (2003)
[Publications] G.Asano etc.: "Good Ferroelectricity of Pb(Zr,Ti)O_3 Thin Films Fabricated by Highly Reproducible Deposition on Bottom Ir Electrode at 395℃"Japanese Journal of Applied Physics. 42(9AB). L1083-L1086 (2003)
[Publications] S.Yokoyama etc.: "Large piezoelectric response in (111)-oriented epitaxial Pb(Zr,Ti)O_3 films consisting of mixed phases with rhombohedral and tetragonal symmetry"Applied Physics Letters. 83(12). 2408-2410 (2003)

2003 Fiscal Year Annual Research Report

強誘電体薄膜の物性制御と次世代メモリデバイスへの応用

Principal Investigator

奥山 雅則 大阪大学, 基礎工学研究科, 教授 (60029569)

Research Products

[Publications] A.Shibuya etc.: "Natural-Superlattice-Structured Ferroelectric Bi_4Ti_3O_<12>-SrBi_4Ti_4O_<15> Thin Films Prepared by Pulsed Laser Deposition"Japanese Journal of Applied Physics. 42. 5986-5989 (2003)

[Publications] K.Y.Yun etc.: "Prominent ferroelectricity of BiFeO_3 thin films prepared by pulsed-laser deposition"Applied Physics Letters. 83. 3981-3983 (2003)

[Publications] M.Takahashi etc.: "Photoelectron Spectroscopic Studies of Bismuth-Excess Strontium Bismuth Tantalate Thin Films and their High-Pressure-O_2-Annealing Effects"Journal of Applied Physics. 94. 6729-6734 (2003)

[Publications] M.Takahashi etc.: "Photoyield and x-ray-photoelectron spectroscopic studies of O_2-annealing effects on SrBi_2Ta_2O_9 thin films prepared by pulsed laser deposition"Journal of Applied Physics. 94. 1912-1917 (2003)

[Publications] A.Shibuya etc.: "Preparation and basic properties of ferroelectric thin films having a superlattice structure of 2 Bi_3TiNbO_9 units-1 Bi_4Ti_3O_<12> unit"Applied Physics Letters. 83. 1411-1413 (2003)

[Publications] Z.Wei etc.: "A Very Low-Temperature Growth of BaTiO_3 Thin Film by Hydrothermal Treatment Following Sol-Gel Coating at 200 Degree Celsius"Integrated Ferroelectrics. 52. 111-118 (2003)

[Publications] Kwi-Young Yun etc.: "Effects of Annealing Atmosphere on Crystallization and Electrical Properties in BiFeO_3 Thin Films by Chemical Solution Deposition(CSD)"Journal of The Korean Physical Society. 42. S1153-S1156 (2003)

[Publications] M.Takahashi etc.: "X-ray Photoelectron and UV Photoyield Spectroscopy on Sr_xBi_yTa_2O_9 Films"Journal of The Korean Physical Society. 42. S1399-S1403 (2003)

[Publications] A.Shibuya etc.: "Oxygen Annealing Effects in Natural-Superlattice-Structured Bi_4Ti_3O_<12>-SrBi_4Ti_4O_<15> Ferroelectric Thin Films"Journal of The Korean Physical Society. 42. S1339-S1342 (2003)

[Publications] K.Saito etc.: "Structural characterization and 90° domain contribution to ferroelectricity of epitaxial Pb(Zr_<0.35>,Ti_<0.65>)O_3 thin films"Journal of Applied Physics. 93(1). 545-550 (2003)

[Publications] G.Asano etc.: "Good Ferroelectricity of Pb(Zr,Ti)O_3 Thin Films Fabricated by Highly Reproducible Deposition on Bottom Ir Electrode at 395℃"Japanese Journal of Applied Physics. 42(9AB). L1083-L1086 (2003)

[Publications] S.Yokoyama etc.: "Large piezoelectric response in (111)-oriented epitaxial Pb(Zr,Ti)O_3 films consisting of mixed phases with rhombohedral and tetragonal symmetry"Applied Physics Letters. 83(12). 2408-2410 (2003)

奥山雅則大阪大学, 基礎工学研究科, 教授 (60029569)