Low-temperature Preparation and Evaluation of Ferroelectric Thin Films for FeRAM by Chemical Solution Process

化学溶液法FeRAM铁电薄膜的低温制备与评价

• 批准号: 11650702
• 负责人: HAYASHI Takashi
• 金额: $ 2.43万
• 依托单位: Shonan Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11650702/
• 关键词: Chemical Process; FeRAM; SrBi_2Ta_2O_9; Thin Films; Excimer UV; Spin-Coating; Metal Alkoxide; 化学溶液法; 強誘電性; ビスマス層状化合物; 低温プロセシング; エキシマレーザー; ゾル・ゲル法; ビスマス系; ゾル・ゲル

Recently, Bi-layered perovskite thin films such as Bi_4Ti_3O_<12>, SrBi_2Ta_2O_9 and SrBi_2Nb_2O_9 have been attracting much attention for use in nonvolatile random access memory (NvRAM) devices. Among them, SrBi_2Ta_2O_9 (SBT) thin films have an especially high potential for NvRAM applications, because SBT has superior fatigue-free properties and small coercive fields, Ec. SBT thin films have been fabricated predominantly by Sol-Gel method with metal alkoxides. It is very important to control the structure and crystallinity of SBT thin films in order to obtain the excellent ferroelectric properties. Low-temperature preparation of SBT thin films is desired for the application to silicon device. In this work, we focussed on the preparation and properties of SBT thin films using Excimer UV irradiation. Thin films of SBT gels were prepared on Pi (200nm)/Ti (50nm)/SiO_2/Si substrates by a spin-coating technique from alkoxide solutions of SBT precursors. The gel thin films were irradiated using Xe excimer UV lamp at various temperatures for 5min. The UV-processed films were calcined at 500℃ for 30min, and then annealed at 750℃ for 1h in an O_2 atmosphere. The SBT thin films exhibited random orientation with strong (115) orientation. The microstructure of the films consisted of fine grains of 0.1〜0.2μm. Strong IR absorption assigned to C-H group was observed in SBT gel films with Excimer UV irradiation in N_2 atmosphere, in contrast with the irradiation in O_2 atmosphere. The crystallinity of the prepared films was improved by the UV irradiation at 200℃. SBT thin films showed well-saturated P-E hysteresis curve with a remanent polarization of 4.1μC/cm^2 and coercive field of 88.7kV/cm. SBT thin films showed a dense microstructure with grain sizes of 500〜600nm

近年来，双层钙钛矿薄膜如Bi_4Ti_3O_<12>、SrBi_2Ta_2O_9和SrBi_2Nb_2O_9在非易失性随机存取存储器（NvRAM）器件中的应用备受关注。其中，SrBi_2Ta_2O_9 （SBT）薄膜具有优异的无疲劳性能和小矫顽场等优点，在NvRAM应用中具有很高的潜力。SBT薄膜主要采用溶胶-凝胶法制备。控制SBT薄膜的结构和结晶度是获得优异铁电性能的关键。低温制备SBT薄膜是应用于硅器件的必要条件。本文主要研究了准分子紫外辐照制备SBT薄膜及其性能。以SBT前驱体醇盐溶液为原料，采用旋涂技术在Pi (200nm)/Ti (50nm)/SiO_2/Si衬底上制备了SBT凝胶薄膜。用Xe准分子紫外灯在不同温度下照射凝胶薄膜5min。将紫外光处理膜在500℃下煅烧30min，然后在O_2气氛下750℃退火1h。SBT薄膜表现出随机取向，具有强（115）取向。薄膜的微观结构为0.1 ~ 0.2μm的细晶粒。在N_2气氛下，准分子紫外辐照下，SBT凝胶膜对C-H基团有较强的红外吸收，而在O_2气氛下则相反。在200℃的紫外照射下，制备的薄膜结晶度得到了改善。SBT薄膜的P-E滞回曲线饱和良好，剩余极化为4.1μC/cm^2，矫顽力场为88.7kV/cm。SBT薄膜微观结构致密，晶粒尺寸为500 ~ 600nm

项目成果

Hisao SUZUKI: "Orientation Control of Low-Temperature Processed Pb(Zr,Ti)O_3 Thin Films"Trans.Mater.Res.Soc,Jpn. 24. 39-42 (1999)

Hisao SUZUKI：“低温处理的 Pb(Zr,Ti)O_3 薄膜的取向控制”Trans.Mater.Res.Soc，Jpn。

T.Hayashi: "Preparation and Dielectric Properties of SrBi_2Ta_2O_9 Thin Films by Sol-Gel Method"J.Europ.Ceram.Soc.. 19. 1497-1500 (1999)

T.Hayashi：“溶胶-凝胶法制备SrBi_2Ta_2O_9薄膜及其介电性能”J.Europ.Ceram.Soc.. 19. 1497-1500 (1999)

Takashi HAYASHI: "Low-Temperature Sintering of PZT Powders Coated with Pb_5Ge_3O_<11> by Sol-Gel Method"J.Europ.Ceram.Soc.. 19. 999-1002 (1999)

Takashi HAYASHI：“通过溶胶-凝胶法低温烧结涂有 Pb_5Ge_3O_<11> 的 PZT 粉末”J.Europ.Ceram.Soc.. 19. 999-1002 (1999)

Takashi HAYASHI: "Preparation and Properties of Nb-Coated Barium Titanate Composite Particles by Surface Modification with Nb alkoxide in Hydrophobic Solvent"J.Sol-Gel Sci.and Tech.. 16. 159-164 (1999)

Takashi HAYASHI：“在疏水性溶剂中用铌醇盐进行表面改性制备铌包覆的钛酸钡复合颗粒及其性能”J.Sol-Gel Sci.and Tech.. 16. 159-164 (1999)

T.Hayashi: "Preparation and Properties of Nb-Coated Barium Titanate Composite Particles by Surface Modification with Nb Alkoxide in Hydrophobic Solvent"J.Sol-Gel Sci. and Tech.. 16. 159-164 (1999)

T.Hayashi：“在疏水性溶剂中用铌醇盐进行表面改性制备铌包覆的钛酸钡复合颗粒及其性能”J.Sol-Gel Sci。