一种利用夹层Ta难熔金属提高NiSi薄膜热稳定性的新方法

A Thin Tantalum Interlayer on the Thermal Stability and Electrical of NiSi Film

本文首次给出了一种具有规律性的能用来提高镍硅化物热稳定性的方法.依据此方法,首次摸索出在Ni中掺入夹层金属Ta来提高NiSi硅化物的热稳定性.Ni/Ta/Ni/Si样品经600~800℃快速热退火后,薄层电阻率保持较小值,约2Ω/□.XRD衍射分析结果表明,在600~800℃快速热退火温度下形成的Ni（Ta）Si薄膜中只存在低阻NiSi相,而没有高阻NiSi2相生成,从而将NiSi薄膜的低阻温度窗口的上限从700℃提高到800℃,使形成高阻NiSi2相的最低温度提高到850℃.AES俄歇能谱,RBS卢瑟福背散射和AFM原子力显微镜分析表明,夹层金属层Ta在镍硅化反应中向表面移动,其峰值距离薄膜顶层2nm左右,在阻止氧原子参与镍硅化反应中起到很好的屏蔽层作用.Ni（Ta）Si薄膜中Ta与Ni的原子比约为2.1∶98,硅化物薄膜界面平整,均方根粗糙度仅为1.11nm.研制的高压Ni（Ta）Si/Si肖特基硅器件在650~800℃温度跨度范围内保留了与NiSi/Si肖特基相近的整流特性,因此Ni（Ta）Si硅化物在深亚微米集成电路制造中是一种令人满意的互连和接触材料.

A novel method with the property of law was for the first time put forward to improve the thermal stability of NiSi film.According to the way,adding a thin Tantalum interlayer within the nickel film was first reported to effectively improve the thermal stability of nickel monosilicide.After rapid thermal annealing（RTA） at temperatures ranging from 600℃ to 800℃,the sheet resistance of formed Ni（Ta）Si samples was about 2Ω/□,and its value is also lower than that of nickel monosilicide without the interlayer.X-ray diffraction（XRD）,AES,RBS and AFM results both reveal that NiSi phase exists in these samples,but the high resistance NiSi2 phase does not exist because tantalum interlayer as the diffusion barrier for oxygen element moved to the top of the thin film after rapid thermal annealing.Fabricated Ni（Ta）Si/Si Schottky barrier diodes with the guard ring structure displayed good quality,with the barrier height being located generally about 0.64 eV and the ideality factor approaching unity.Therefore,It shows that Ni（Ta）Si is a satisfactory local connection and contact material.