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用于硅基含铜铁电电容器集成的Ti-Al阻挡层

Ti-Al Barrier Layer for Integrating Ferroelectric Capacitor on Si with Copper

【作者】 邢金柱

【导师】 刘保亭;

【作者基本信息】 河北大学 , 微电子学与固体电子学, 2009, 硕士

【摘要】 磁控溅射法制备了Ti-Al(40 nm),超薄Ti-Al(4 nm)薄膜,分别采用X射线衍射仪(XRD)、原子力显微镜(AFM)、四探针检测仪(Four-Point Probe)、高分辨透射电子显微镜(HRTEM)对阻挡层性能进行了分析。研究了退火温度对Ti-Al薄膜阻挡性能的影响。研究发现温度从室温到750℃样品表面粗糙度和方块电阻没有急剧升高,并且XRD曲线中没有Cu-Si等杂相出现。600℃退火后超薄非晶Ti-Al阻挡层(4 nm)临界面之间仍然是非常清晰平整,并没有反应和互扩散的发生。以上研究数据说明Ti-Al(40 nm)和Ti-Al(4 nm)阻挡层在750℃仍保持良好的阻挡效果。通过磁控溅射法制备了超薄复合阻挡层Ta(5 nm)/Ti-Al(5 nm)。通过XRD、AFM、FFP对阻挡性能进了研究。样品在高达800℃退火温度下仍然没有硅铜化合物的出现,Ti-Al保持非晶状态,样品均方根粗糙度和方块电阻并没有明显升高。以上研究数据说明超薄复合阻挡层Ta(5 nm)/Ti-Al(5 nm)在高达800℃高温下表现出了良好的阻挡性能。应用Ti-Al作为抗氧化阻挡层,采用磁控溅射法和溶胶.凝胶法构架了Pt/LSCO/Pb(Zr, Ti)O3(PZT)/LSCO/Ti-Al/Cu/Ti-Al/Si铁电电容器异质结,实现了Cu薄膜与铁电电容器的集成。通过铁电测试仪(Precision LC United)对样品的铁电性能进行了研究。研究发现在驱动电压为10 V时,样品具有饱和趋势良好的电滞回线,剩余极化强度为18μC/cm2,矫顽电压为1.5 V。研究了Ti-Al薄膜的阻挡性能和抗氧化性能,为铜与铁电电容器集成提供了重要的数据。

【Abstract】 Ti-Al film(40 nm)、ultra-thin Ti-Al film(4 nm) have been deposited on the Si(001) substrates by magnetron sputtering method. X-ray diffraction (XRD), atomic force microscopy (AFM), four-point probe measurement (FFP), high resolution transmission electron microscopy (HRTEM) have been employed to characterize the barrier performance. Impacts of annealing temperature on the barrier performance of Ti-Al film have been studied. No dramatic increases of surface roughness and sheet resistance have been observed, moreover, no impurity peaks, such as Cu-Si are found in the XRD curves of Cu/Ti-Al/Si heterostructures annealed at temperatures lower than 750℃.HRTEM results indicate that the interfaces of the samples, annealed at 600℃,are sharp and clean, and no obvious reaction or interdiffusion is observed, implying Ti-Al film(40 nm) and ultra-thin Ti-Al film(4 nm) have very good barrier performance up to 750℃.The ultra-thin bilayer Ta(5 nm)/Ti-Al(5 nm) have been deposited by magnetron sputtering, XRD,AFM, FFP techniques have been used to study the barrier performance. No copper silicide is found after 800℃annealing, moreover, Ti-Al film is still amorphous. Surface roughness and sheet resistance of the samples do not increase obviously, demonstrating that the bilayer Ta(5 nm)/Ti-Al(5 nm) can be used as a diffusion barrier layer at annealing temperature of 800℃.Pt/(La0.5Sr0.5)CoO3(LSCO)/Pb(Zr,Ti)O3(PZT)/LSCO/Ti-Al/Cu/Ti-Al/Si heterostructure has been fabricated via both Sol-Gel and magnetron sputtering methods using Ti-Al film as diffusion barrier layers. Ferroelectric tester (Precision LC Unit) has been used to measure the ferroelectric properties.It is found that the LSCO/PZT/LSCO capacitor has very good saturated ferroelectric loop, remnant polarization and coercive voltage of LSCO/PZT/LSCO capacitor, measured at 10 V, are~18.0μC/cm2 and~0.7 V, respectively. Ti-Al film is used as diffusion barrier layer between Cu and Si as well as oxygen barrier layer between Cu and oxide electrode, providing very important data for integrating Si based ferroelectric random access memory with Cu metallization.

  • 【网络出版投稿人】 河北大学
  • 【网络出版年期】2012年 02期
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