Atom-probe for FinFET dopant characterization

With the continuous shrinking of transistors and advent of new transistor architectures to keep in pace with Moore's law and ITRS goals, there is a rising interest in multigate 3D-devices like FinFETs where the channel is surrounded by gates on multiple surfaces. The performance of these devices depends on the dimensions and the spatial distribution of dopants in source/drain regions of the device. As a result there is a need for new metrology approach/technique to characterize quantitatively the dopant distribution in these devices with nanometer precision in 3D.In recent years, atom probe tomography (APT) has shown its ability to analyze semiconductor and thin insulator materials effectively with sub-nm resolution in 3D. In this paper we will discuss the methodology used to study FinFET-based structures using APT. Whereas challenges and solutions for sample preparation linked to the limited fin dimensions already have been reported before, we report here an approach to prepare fin structures for APT, which based on their processing history (trenches filled with Si) are in principle invisible in FIB and SEM. Hence alternative solutions in locating and positioning them on the APT-tip are presented. We also report on the use of the atom probe results on FinFETs to understand the role of different dopant implantation angles (10° and 45°) when attempting conformal doping of FinFETs and provide a quantitative comparison with alternative approaches such as 1D secondary ion mass spectrometry (SIMS) and theoretical model values.     

窄脉冲保形全方位离子注入技术

叙述了全方位离子注入过程中,由于被处理零件与其周围离子鞘层之间厚度的增加,引起零件与鞘层之间保形性变差,导致零件表面注入剂量不均匀性;文中系统分析了注入电压、等离子体密度、脉冲宽度和脉冲频率等处理工艺参数对注入剂量不均匀性的影响,用鞘层动力学计算机数值模拟方法从理论上研究了轴承内外圈处理中工艺参数对注入剂量不均匀性的影响,并用实验方法进行了测量验证,理论研究和试验测量结果的一致性,说明所提出的窄脉冲保形全方位离子注入技术完全适用于复杂形状零件表面均匀强化处理。     

Conformality of thermal and plasma enhanced atomic layer deposition on a non-woven fibrous substrate

Alumina was deposited on a non-woven polyester fiber substrate using both thermal and plasma enhanced atomic layer deposition (ALD). The textile was confined inside a one dimensional test structure. The coverage of the ALD film on the nonwoven as a function of depth in the test structure was determined by energy dispersive X-ray spectroscopy (EDX). A model is introduced which links the precursor transport in the nonwoven (transmission, reflection and deposition) with the nonwoven properties (density, fiber surface area, density of surface sites). The experimental results are compared to simulations of the coverage profile. It is shown that longer precursor exposure times result in deposition deeper inside the nonwoven. However, the majority of precursor molecules entering the nonwoven leave the test structure without contributing to film growth. ALD from TMA and oxygen plasma had a very limited penetration into the nonwoven because of radical recombination. This effect is relevant for plasma treatment of fibrous materials in general.     

CONFORMALITY AND COMPOSITION OF FILMS DEPOSITED AT LOW PRESSURES

Conformality limitations and film composition variations inside features for films deposited at low pressures are explained using examples of studies which combine transport and reaction simulations of deposition processes and carefully designed experimental work. In the first example, the use of film profile information to decide between two kinetic models for the deposition of SiO₂ from TEOS is described. In the second example, composition profiles in sputter deposited Ti-W are explained in terms of titanium re-emission. Combined simulation and experimental studies of film profiles and composition profiles in features is a valuable tool in efforts to arrive at useful kinetic and transport models.