射频磁控溅射制备PZT铁电薄膜的工艺研究

在SiO2/Si基片上采用直流对靶溅射技术制备出Pt/Ti底电极;应用射频磁控溅射方法,利用快速热处理(RTA)工艺,制备出了具有良好铁电性能的Pb(Zr0.52Ti0.48)O3铁电薄膜.将样品进行10min快速热退火处理,退火温度700℃.测试分析表明:薄膜厚度比较均匀、表面基本平整、没有裂纹和孔洞、致密性好、薄膜样品的矫顽场强(Ec)为28.6kV/cm,剩余极化强度(Pr)为18.7μC/cm2,自发极化强度(Ps)为37.5μC/cm2,是制备铁电薄膜存储器的优选材料.     

Pb用量对锆钛酸铅薄膜微观结构和铁电性能的影响

在Pt/Ti/SiO2/Si基片上,通过多次匀胶旋涂-预热处理工艺制备了PbTiO3(PT)无机薄层夹心的锆钛酸铅(lead zirconate titanate,PZT)薄膜,然后经650℃退火处理得到了所需的具有钙钛矿结构的PZT铁电薄膜.用X射线衍射、原子力显微镜表征了PZT铁电薄膜微观结构,并测试铁电性能.结果表明:制备PT层时的Pb用量对得到的PZT铁电薄膜的微观结构和铁电性能有重要影响.当Pb过量15%(摩尔分数)左右时,得到的PZT铁电薄膜不仅晶界清晰,晶粒尺寸分布均匀,具有纯钙钛矿结构,而且铁电性能优异,剩余极化强度Pr=21μC/cm2,矫顽场Ec=37kV/cm.     

热处理工艺对钙锶铋钛铁电薄膜性能的影响

用溶胶-凝胶法和快速退火技术在带白金电极和钛过渡层的硅片(Pt/Ti/SiO2/Si)上制备了钙锶铋钛(Ca0.4Sr0.6Bi4Ti4O15,CsBT-0.4)铁电薄膜.结果表明:退火温度及保温时间对CSBT-0.4铁电薄膜的微观结构、晶粒取向以及铁电性能的影响较大.x射线衍射谱表明:退火温度为750℃、保温时间为5min,得到的CsBT-0.4铁电薄膜样品的晶粒大小较均匀且致密性好,而且晶粒以a轴取向的球状晶粒为主,剩余极化强度(2Pr)和矫顽场(2Ec)分别为16.2 μC/cm2和130kV/cm.     

磁场处理对聚偏二氟乙烯复合材料介电性能的影响

以镍沉积钛酸铜钙纳米颗粒(NC)为填料,通过流延法制备聚偏二氟乙烯(PVDF)/NC复合薄膜(PNC),研究磁场对PNC复合材料介电性能的影响。结果表明：40 nm的镍颗粒沉积在直径200 nm的钛酸铜钙球形颗粒表面。不同磁场强度结合温度处理能够促进PNC复合材料的极化响应,从而有效调控其介电性能。高温强磁场(150℃-1.5 T)能够引发PNC复合材料的绝缘-导电相变。而30℃与1.0 T的最佳磁场条件下,增加PNC复合材料的界面极化强度,显著提升其介电性能,使PNC复合材料在10 Hz频率下获得高介电常数(21)、低介电损耗(0.10)和低电导率(1.0×10^-11S/cm)等介电性能。     

生长温度对单晶衬底上生长Ba(Zr_(0.2)Ti_(0.8))O_3薄膜微结构和介电性能的影响(英文)

采用脉冲激光沉积方法,在制备有LaNiO3(LNO)底电极的LaAlO3(LAO)衬底上,分别在500,600℃和700℃的沉积温度下制备了锆钛酸钡Ba(Zr0.2Ti0.8)O3(BZT)薄膜.通过X射线衍射表征薄膜的结构特性,原子力显微镜和扫描电子显微镜分别用来表征样品的表面和断面形貌.结果表明:BZT薄膜与LNO具有c轴取向,并以cube-on-cube方式排列生长.BZT薄膜表面致密无裂缝,具有柱状生长的晶粒.薄膜的介电性能测试显示:600℃下沉积的BZT薄膜具有较高的介电可调性(49.1%)和较低的介电损耗(2.5%).在600℃下沉积的BZT薄膜的优值因子(figure of merit,FOM)达到19.8.     

Mg掺杂对Ba0.5Sr0.5TiO3薄膜介电性能的影响

用醋酸盐和钛酸四丁酯为原料,采用sol-gel工艺在Pt/TiO/SiO/Si基片上制备了含有Mg元素的Sr0.5Ba0.5-xMgxTiO3薄膜,其退火处理温度为750℃.通过X射线衍射和扫描电镜分析技术研究了薄膜的相结构和形貌.采用美国HP Angilent 4294A阻抗分析仪测试了以Pt为底电极、Ag为上电极的MFM电容器的介电性能.实验结果表明:掺镁Sr05Ba05.xMgxTiO3薄膜较未掺杂的Ba05Sr0.5TiO3薄膜相对介电常数高、介电损耗低.介温谱表明在居里温度附近发生了弥散型相变,且居里温度有向低温方向漂移的趋势.     

铁电薄膜存储器底电极Pt/Ti的制备及性能研究

应用射频磁控溅射方法 ,在Si基片上采用不同的溅射工艺制备了铁电薄膜底电极Pt/Ti,并分析了在不同温度下退火后材料的电导率性能和粘结力性能 ,从理论和实验上分析了不同的溅射工艺和退火处理对底电极性能的影响。     

退火工艺对Pb(Zr_(0.55)Ti_(0.45))O_3铁电薄膜结晶取向的影响

用射频磁控溅射法在Pt(111)/Ti/SiO2/Si上成功的制备了Pb(zr0.55Ti0.45)O3(PZT)铁电薄膜,通过传统退火(CFA)和快速退火(RTA)不同的退火方式,获得了(100)和(111)择优取向的铁电薄膜。对薄膜电学特性的测试表明,薄膜的织构对其电学性能有很大影响,(111)取向的薄膜与(100)取向的薄膜相比,剩余极化Pr和矫顽场Ec较大,但抗疲劳特性却较差。     

晶粒尺寸和膜厚对磁控溅射法制备Bi_(1.5)Mg_(1.0)Nb_(1.5)O_7薄膜介电性能的影响（英文）

采用磁控溅射法在Pt/Ti/Si O2/Si基底上制备立方焦绿石结构Bi1.5Mg1.0Nb1.5O7薄膜。通过控制750℃下后退火时间来控制薄膜的平均晶粒尺寸,用沉积时间控制膜厚。研究不同晶粒尺寸和膜厚对BMN薄膜相结构、微观形貌和介电性能的影响。结果表明,当BMN薄膜平均晶粒尺寸为45 nm、膜厚为430 nm时,薄膜介电性能提高显著,1 MHz下介电常数为112.4,介电损耗为0.001 82,在0.93 MV/cm外加电场条件下,介电调谐率为27.7%。     

硅基铌掺杂Bi_4Ti_3O_(12)薄膜溶胶-凝胶工艺的制备及铁电性改善研究

采用溶胶-凝胶(Sol-Gel)法制备了铌元素(Nb)取代Ti元素的Bi4Ti3O12(BTN)铁电薄膜,研究不同掺杂浓度,不同退火温度等工艺对BTN薄膜的微观特性及剩余极化强度、矫顽场等电性能的影响。研究表明,650℃进行退火的BTN薄膜生长形态,晶粒开始呈棒状生长;当温度高于850℃时,薄膜的c轴生长取向增长趋势不再明显。铁电性方面,对Ti进行2%掺杂取代的BTN薄膜的铁电性能最佳。从而获得了BTN薄膜制备的合理工艺参数。     

Electrical properties of sputtered PZT films on stabilized platinum electrode

PZT (54/46) thin films were deposited by r.f. magnetron sputtering followed by a post-annealing treatment on silicon substrates. The crucial role of a Ti adhesion layer on the Ti/Pt bottom electrode is presented. The deposition conditions and the thickness of Ti have dominant effects on the interactions between Ti and Pt during the annealing treatment. The Pt layer, whatever its thickness, did not act as a barrier against Ti-out diffusion. The stability of the bottom electrode was achieved by using a TiO_x layer instead of a pure metallic Ti adhesion layer. The electrical properties of PZT films in terms of dielectric and ferroelectric performance were evaluated, particularly as a function of the PZT film thickness.     

The preparation and properties of PZT thin film by sputering method

The ferroelectric PZT thin films were prepared on Pt/Ti/SiO₂/Si substrate by RF sputtering method followed by the rapid thermal annealing. The preparation of the Pt and Ti thin films as bottom electrode, and their influences on the PZT thin films were studied in details. The substrate temperature during sputtering was room temperature; the rapid thermal annealing temperature was 500°C-750°C and the annealing time was 30-70s. The influences of different preparation parameters on the structure and electric properties were studied with X-ray diffraction technique and RT66A Standardized Ferroelectric Test System. The electric properties of the prepared PZT thin film was: P_a=39μc/cm₂, P_r = 9.3 μc/cm², E_c=28KV/mm, ε=300, p=10⁹ω⋅cm.     

SrBi_2Ta_2O_9薄膜的制备和铁电性能研究

用一种新的低温过程制备了SrBi2Ta2O9铁电薄膜。在Sol-Gel方法中用Pt/Ti/SiO2/Si作衬底,研究了薄膜的结构和电特性。SrBi2Ta2O9薄膜在淀积Pt上电极之前和之后都要退火,第一次退火在760乇氧压下600℃时退火30分钟,在第二次退火后薄膜结晶良好。     

Preparation of Lead Zirconate Titanate Thin Films Derived by Hybrid Processing: Sol-Gel Method and Laser Ablation

Thin films of Pb(Zr_0.52Ti_0.48)O₃ (PZT) were prepared by hybrid processing (sol-gel and excimer laser ablation) on Pt/Ti/SiO₂/Si substrates. Crystalline phases and microstructures of the PZT films were investigated by X-ray diffraction analysis and scanning electron microscopy, respectively. Electrical properties of the films were evaluated by measuring their P - E hysteresis loops and dielectric constants. The temperature of postdeposition annealing in hybrid processing was lower than that in the case of direct film deposition by laser ablation on a Pt/Ti/SiO₂/Si substrate. The preferred orientation of the films derived by hybrid processing could be controlled using the seeding layer deposited by the sol-gel process. The films fabricated by hybrid processing consisted of the perovskite phase with a (111) preferred orientation and had good ferroelectric properties.     

The influence of chemical passivation on the PZT/Pt electrode interface

It has been recognized that the interdiffusion of atomic species between a PZT film and the Pt bottom electrode leads to the gradual degradation of a PZT capacitor. In order to prevent this interdiffusion, experimental studies on chemical passivation to the bottom electrode surface were carried out by the sulfurization method. It was observed that a sulfur layer was built up on the Pt substrate with small grains, which resulted in a structural change at the Pt surface. Atomic force microscopy (AFM) showed that the film roughness of the Pt surface was increased by sulfur treatment. Pb(Zr_0.5Ti_0.5)O₃(PZT) thin films were prepared on a Pt/Ti/SiO₂Si bottom electrode by spin-coating techniques. The microstructure and the preferred orientation of the PZT films were shown to depend on the sulfur-treated electrode. The PZT capacitor on a clean Pt electrode was confirmed to be ferroelectric with Pr=17.7 μC/cm² and Ec=65 kV/cm from the P-E hysteresis curves. The fatigue behavior of a PZT film capacitor prepared on a sulfur-treated one was observed to be relaxed, but the absolute value of Pr was paid off.     

Use of Transmission Electron Microscopy for the Characterization of Rapid Thermally Annealed, Solution-Gel, Lead Zirconate Titanate Films

The microstructure and preferred orientations of rapid thermally annealed Pb(Zr_0.53,Ti_0.47)O₃ films, deposited on Pt/Ti/SiO₂/Si electrode/substrates by solution-gel spinning, have been investigated using analytical and high-resolution electron microscopy and X-ray diffraction. The temperature of pyrolysis of the PZT films was found to influence the preferred orientation of the film: lower temperatures (350°C) favored a (111) orientation, whereas higher temperatures (420°C) favored a (100) orientation. Excess Pb was used to control the A-site stoichiometry of the film particularly at the film surface where Pb-deficient crystals could often be observed. The absence of these crystals was shown to be correlated with an improvement in the dielectric response.     

Effects of a Conducting LaNiO3 Thick Film as a Buffer Layer of a Pb(Zr,Ti)O3 Film on Titanium Substrates

A conducting 8-μm-thick LaNiO₃ (LNO) film was deposited on a Ti substrate by aerosol deposition for use as a diffusion barrier between a lead zirconate titanate (PZT) and a Ti substrate during postannealing. The deposited 20-μm-thick PZT films were annealed at 800°C. The PZT film deposited without LNO was cracked and partially detached from the substrate after postannealing, presumably due to a severe reaction with the Ti substrate, while no significant reactions were observed when the LNO buffer layer was used. The remnant polarization and relative dielectric constant of the 20-μm-thick annealed PZT films deposited on the LNO-buffered Ti substrate were 43 μC/cm² and 1010, respectively.     

Highly Oriented, Chemically Prepared Pb(Zr, Ti)O3 Thin Films

We have fabricated highly oriented, chemically prepared thin films of Pb(Zr_0.04Tio._0.60)O₃ (PZT 40/60) on both insulating and conducting substrates. While (100) MgO single crystals were used as the insulating substrates, the conducting substrates. were fabricated by RF magnetron sputter deposition of 100-nm-thick (100) Pt films onto (100) MgO substrates. For comparison, we also fabricated PZT 40/60 films that had no significant preferential orientation on platinized MgO substrates. Sputter deposition of an underlying amorphous Pt film was used to fabricate randomly oriented PZT 40/60 films. Highly (001) oriented PZT 40/60 films had higher remanent polarization (61 μC/cm² compared to 41 μC/cm²) and lower relative dielectric constant (368 compared to 466) than PZT 40/60 films that were randomly oriented.