【作者】 余涛；

【导师】 诸葛兰剑； 吴雪梅；

【作者基本信息】 苏州大学 ， 材料物理与化学， 2011， 硕士

【摘要】 为了解决由栅介质层过薄而引起的漏电流显著增加的难题,人们引入了一种具有高介电常数（高k）的材料来取代传统的SiO2。其中,铪基高k材料由于具备较高的介电常数和结晶温度、优异的界面特性和热稳定性以及低的频率色散和漏电流被广泛关注。本实验采用双离子束沉积系统在本底真空5×10^-4 Pa和工作气压3.2×10^-2 Pa条件下,于电阻率为3⁸cm的Si衬底上成功制备了高质量的Ta₂O₅和HfTaO薄膜。着重探究了薄膜微结构、介电特性与辅源离子能量、掺杂含量之间的潜在关系。此外,还研究了不同金属栅电极（Ag、Au、Pt）对HfTaO基MOS电容漏电流、电容值、可靠性、导电机制的影响。实验结果显示:（a）在辅源能量200eV下制备的Ta₂O₅薄膜具有最小的表面粗糙度和优异的界面特性。由C-V/I-V特征曲线表明,200eV下制备的Ta₂O₅基MOS电容具有最小的平带电压偏移量、等效氧化层密度以及漏电流。研究表明合适的辅源能量可有效改善薄膜生长机制,使薄膜由类岛状沉积转化为层状生长,从而提高晶粒均匀性、薄膜平整度以及致密性,使薄膜具有较好的电学性质。（b）通过向HfO2中掺杂Ta元素,可有效提高其物理、电学特性。尤其是Hf0.54Ta0.46O样品显示了大的介电常数（²2）,高的结晶温度900℃,小的平带电压偏移、氧化层电荷密度以及漏电流。（c）由于Pt金属具有高的功函数φm s（Pt）=5.65eV,因此Pt/HfTaO/Si/Pt电容在等效厚度Eot小于Ag, Au样品的情况下,仍然具有最小的漏电流。总言之,Pt金属极具成为下一代MOS器件中栅电极的潜质。更多还原

【Abstract】 In order to solve a remarkable increase in tunneling leakage current through the ultra-thin gate dielectrics, materials with a high dielectric constant （high k） have been introduced as gate dielectrics alternative to conventional SiO2, Hf-based high-k materials have been drawn attention for a long time because of its high dielectric constant and crystallization temperature, excellent interfacial properties and thermal stabilities, low frequency dispersion and leakage current density.In this letter, Ta₂O₅ and HfTaO thin films were deposited on p-type Si substrate with a resistively of 3⁸ cm using an dual ion beam sputtering deposition technique （DIBSD） at a base pressure of 5×10^-4 Pa and work pressure of 3.2×10^-2 Pa. A special focus of the study is to reveal the association between the structure, dielectric properties and the various ion beam energy of the assisted ion source as well as the content of doping elements. Besides, influence of the different metal electrodes （Ag、Au、Pt） on the leakage currents, capacity, reliable characteristics and conduction mechanism of HfTaO-based capacitor have been studied.The experimental results indicated that: （a） the Ta₂O₅ film prepared under 200eV have the smallest surface roughness and excellent interfacial characteristics. C-V and I-V characteristic curves indicate that the Ta₂O₅ MOS has the minimum value of flat voltage offset, density of oxides charges and leakage current. Eventually we found the appropriate assisted source energy can effectively improve the film’s growth mechanism and makes the film growth type from the island into a layered, which will improve the uniformity of crystalline grain and the film’s roughness and compactness. （b）We significantly improved the physical and electrical characteristics of HfTaO gate dielectrics by incorporating Ta into HfO2 films. Especially, Hf0.54Ta0.46O sample exhibited the highest k value（²2） and crystallization temperature of 900℃, the smallest flat-band voltage, oxide-charge density and leakage current. （c） It is proved that the Pt-electrode capacitor still has the smallest leakage current value at a high electric field even though its Eot is lower than that of the Ag, Au-electroded. The result is mainly due to Pt with a high enough work functionφms（Pt）=5.65eV. In a word, it is thus proposed that Pt electrode has a strong potential for future nano MOS devices.更多还原