Ultrathin films of poly-diallyldimethylammonium chloride（PDDA）/polystyrene sulfonate（PSS） and PDDA/poly（3,4-ethylene dioxythiophene）-polystyrene sulfonate（PEDOT-PSS） were constructed on Ta2O5 films through layer-by-layer electrostatic self-assembly（ESA） method for a surface modification purpose.The self-assembly ability of PDDA/PSS and PDDA/PEDOT-PSS ultrathin films on Ta2O5film was investigated.The results showed that the ESA ultrathin films can be constructed on Ta2O5 film surface with a layer-by-layer deposition method,and the Ta2O5film covered with ESA film exhibited smoother surface roughness compared with Ta2O5film without surface modification.Moreover,the electronic performance of Ta/Ta2O5/ESA films/polymer film capacitor structure was investigated.The results revealed that the capacitor composed of ultrathin ESA film exhibited better anti-voltage endurance ability and less leakage current,which resulted from the isolation of leakage current channel in Ta2O5 films because of surface coverage of ultrathin ESA film on Ta2O5.It also can be found that the thicker ultrathin ESA film for surface modification resulted in better anti-voltage endurance ability and higher equivalent series resistance（ESR） of Ta2O5 capacitor.The further investigation confirmed that lower ESR of capacitor composed of PDDA/PEDOT-PSS ESA films because of high conductive ability of PEDOT-PSS.%采用静电自组装方法在五氧化二钽（Ta2O5）介质氧化膜上制备了聚二烯丙基二甲基氯化铵（PDDA）/聚苯乙烯磺酸钠（PSS）和聚二烯丙基二甲基氯化铵/聚-3,4-乙烯二氧噻吩-聚苯乙烯磺酸钠（PEDOT-PSS）超薄膜.研究了两种自组装超薄膜在Ta2O5介质氧化薄膜上的组装特性.结果表明两种自组装膜能够稳定地组装于Ta2O5介质膜表面,并有效降低薄膜的表面粗糙度.进一步研究了两种自组装超薄膜修饰的Ta2O5电容结构的电性能.结果表明静电自组装膜对Ta2O5介质膜表面进行修饰后,有效地隔离了介质氧化膜中的缺陷,降低了电容的漏电流并提高耐电压能力;研究还发现不同厚度的超薄膜对Ta2O5电容结构的耐压特性有不同程度的影响,较厚的薄膜可以更好地提高电容的耐压能力并降低漏电流,但会增加电容的等效串联电阻（ESR）.另外,在相同薄膜层数的情况下,聚合物电解质PEDOT-PSS良好的导电性能降低了复合超薄膜的电阻,使得PDDA/PEDOT-PSS修饰的电容结构ESR值较低.
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