Imec, Kapeldreef 75, B-3000 Leuven, Belgium.
Ultramicroscopy. 2011 May;111(6):540-5. doi: 10.1016/j.ultramic.2011.01.004. Epub 2011 Jan 12.
The laser-assisted Atom Probe has been proposed as a metrology tool for next generation semiconductor technologies requiring sub-nm spatial resolution. In order to assess its potential for the analysis of three-dimensional semiconductor structures like FinFETs, we have studied the Atom Probes lateral resolution on a silicon, silicon-germanium multilayer structure. We find that the interactions of the laser with the semiconductor materials in the sample distort the sample surface. This results in transient errors of the measured dimensions of the structure. The deformation of the sample furthermore leads to a degradation of the lateral resolution. In the experiments presented in this paper, the Atom Probe reaches a lateral resolution of 1-1.8 nm/decade. In this paper we will discuss the reasons for the distortions of the tip and demonstrate that with the present state of data reconstruction severe quantification errors limit its applicability for the quantitative analysis of heterogeneous semiconductor structures. Our experiments show that reconstruction algorithms taking into account the time dependent nanostructure of the tip shape are required to arrive at accurate results.
激光辅助原子探针已被提议作为下一代半导体技术的计量工具，要求具有亚纳米空间分辨率。为了评估其在分析三维半导体结构（如 FinFET）方面的潜力，我们研究了硅、硅锗多层结构上原子探针的横向分辨率。我们发现，激光与样品中半导体材料的相互作用会使样品表面变形。这导致结构的测量尺寸出现瞬时误差。此外，样品的变形会导致横向分辨率降低。在本文中介绍的实验中，原子探针达到了 1-1.8nm/decade 的横向分辨率。在本文中，我们将讨论尖端变形的原因，并证明在当前的数据重建状态下，严重的量化误差限制了其在异构半导体结构的定量分析中的适用性。我们的实验表明，需要采用考虑尖端形状随时间变化的纳米结构的重建算法，才能得到准确的结果。
