FIB参数对低介电常数介质TEM样品制备的影响

研究了使用聚焦离子束(FIB)方法制备低k介质的TEM样品时离子束参数对介质微观形貌的影响,发现低k介质的微观形貌与离子束参数具有较强的相关性。传统大离子束流、高加速电压的FIB参数将导致低k介质多孔性增加、致密度下降;且k值越低,离子束参数影响越大。对于亚65nm工艺中使用的k值为2.7的介质,当离子束流减小到50pA、加速电压降低到5kV时,FIB制样方法对介质致密度的影响基本可忽略,样品微观形貌得到了显著改善;而对于65nm工艺中使用的k值为3.0的介质,其微观形貌受离子束参数的影响则相对较小。

Impact of FIB Parameters on Low-k Dielectric TEM Sample Preparation

Impact of FIB parameters on low-k dielectric TEM sample preparation was investigated. It is found that the micro-morphology of low-k dielectric is greatly impacted by different milling conditions of ion beam. The porosity of low-k dielectric is enhanced by the conventional FIB sample preparation method at high accelerating voltage and large milling current. The lower k value, the more porous profile are enhanced by FIB. The conditions of FIB sample preparation for low-k dielectric of 2.7 are optimized in 65 nm and sub-65 nm technologies based on this work. The optimized ion beam current and accelerating voltage are 50 pA and 5 kV, respectively. As for k value of 3.0, its micro topography is effected relatively small by FIB parameters.