非晶层占比对TEM样品成像的影响

Effect of the Proportion of the Amorphous Layer on the Imaging of TEM Samples

研究了非晶层占比对半导体器件透射电子显微镜(TEM)样品成像的影响。聚焦离子束(FIB)是制备TEM样品的重要工具,在TEM样品制备过程中,离子束损伤会在样品表面产生非晶层而使TEM图像产生畸变失真。在28 nm技术节点以下半导体器件TEM样品制备中,传统的制备方法会使样品在TEM下呈现非晶像或者图像质量不佳而不再适用。制备了一种楔形样品并使用平面转截面的样品制备方法研究了TEM呈晶格像时和非晶层临界占比的关系。实验表明,当样品中非晶层的占比超过0.66时,其在TEM下的成像为非晶像;当低于这一数值时,其在TEM下的成像为晶格像。针对非晶层对样品成像的影响,使用了一种低电压减薄的制备方法,通过降低非晶层占比可以显著优化表面成像,提高TEM样品的质量。

The effect of the proportion of the amorphous layer on the imaging quality of the semiconductor device transmission electron microscope(TEM)sample was studied.Focused ion beam(FIB)is a very important instrument for the preparation of TEM samples.During the preparation of the TEM sample,ion beam damage will produce the amorphous layer on the surface of the sample and distortion of the TEM image.In the preparation of TEM samples of semiconductor devices below the 28 nm technology node,the conventional preparation method is no longer applicable,which makes the sample amorphous or the poor imaging quality.A wedge-shaped sample was prepared,and the relationship between the TEM pre-sented lattice imaging and the critical ratio of the amorphous layer was studied by using a sample preparation method with a planar to transection.The experiments show that when the proportion of the amorphous layer in the sample is more than 0.66,the imaging by using TEM is an amorphous image.When it is lower than 0.66,the imaging by using TEM is a lattice image.Aiming at the effect of the amorphous layer on sample imaging,applying a low voltage thinning preparation method can reduce the proportion of the amorphous layer to optimize surface imaging and improve the qualities of TEM samples.