用于线宽测量的双探针原子力显微镜系统研究

发布时间：2018-11-22 09:40

【摘要】：近年来随着半导体工业的不断发展,集成电路的关键尺寸正向着22nm以下的技术节点迈进。器件尺寸的不断减小,导致关键尺寸成为影响器件电气性能的重要因素。如何有效测量和控制关键尺寸成为纳米计量领域的一大难题。传统的测量工具如光学显微镜(OM)、扫描电子显微镜(SEM)和原子力显微镜(AFM)都不能对关键尺寸进行有效的真三维测量。为此本文提出构建双探针原子力显微镜测量系统,利用双探针针尖对顶测量,有效消除探针尺寸对测量结果的影响。为验证双探针测量的可行性,基于石英音叉探针(A-Probe)开发了原子力显微镜测头。具体工作如下:1.介绍了A-Probe的结构特点及工作原理;建立了音叉探针的力学和电学等效模型;介绍并分析了动态AFM在幅度调制(AM)、频率调制(FM)和相位调制(PM)模式下的工作原理及特点;最后分析了双探针测量如何能消除探针尺寸的影响并给出对针方案。2.为了实现双探针AFM系统测量结果的量值溯源,课题采用了激光干涉仪系统。基于FPGA设计了细分卡接口电路,实现了上位机软件对位置数据的读取、复位操作。验证了等位移间隔触发的功能。3.基于A-Probe探针搭建了单测头实验装置,系统主要由测头、纳米位移台、视觉观测模块、锁相放大器和数字反馈控制系统构成。主要开发了探针夹持机构、探针微弱信号检测电路及基于DSP的数字反馈控制电路。基于此实验装置完成了测头在调幅、调频和调相三种工作模式下的灵敏度及分辨力测试。并对二维栅格样品进行了测量。实验表明,该测头具有纳米级分辨力,能有效对微纳结构进行成像。4.在调幅和调频模式下,进行了双探针对针实验。利用扫描探针对静止探针进行近场力扫描成像。实验结果验证了双探针对顶测量方案具有可行性。
[Abstract]:With the continuous development of semiconductor industry in recent years, the key dimensions of integrated circuits are moving towards the technical node below 22nm. The decreasing of the device size leads to the key size becoming an important factor affecting the electrical performance of the device. How to measure and control the key dimensions effectively becomes a difficult problem in the field of nanometer measurement. Traditional measuring tools such as optical microscope (OM),) scanning electron microscope (SEM) and atomic force microscope (AFM) can not measure the key dimensions effectively. In order to eliminate the influence of probe size on the measurement results, a double probe atomic force microscope (AFM) measurement system is proposed in this paper. In order to verify the feasibility of double probe measurement, an atomic force microscope probe based on quartz tuning fork probe (A-Probe) was developed. The specific work is as follows: 1. The structure and working principle of A-Probe are introduced, and the mechanical and electrical equivalent models of tuning fork probe are established. This paper introduces and analyzes the working principle and characteristics of dynamic AFM in amplitude modulated (AM), frequency modulation (FM) and phase modulated (PM) mode, and finally analyzes how double probe measurement can eliminate the influence of probe size and give the needle scheme. 2. In order to trace the measurement results of double probe AFM system, a laser interferometer system is used. The interface circuit of the subdivision card is designed based on FPGA, and the position data reading and reset operation are realized by the upper computer software. The function of equal displacement interval trigger is verified. 3. A single probe experiment device based on A-Probe probe is built. The system is composed of probe, nanometer displacement table, visual observation module, phase-locked amplifier and digital feedback control system. The probe clamping mechanism, probe weak signal detection circuit and digital feedback control circuit based on DSP are developed. Based on this experimental device, the sensitivity and resolution of the probe in three modes of amplitude modulation, frequency modulation and phase modulation are tested. The two-dimensional grid samples were measured. The experimental results show that the probe has nanometer resolution and can be used to image micro-nano structure effectively. 4. 4. In the mode of amplitude modulation and frequency modulation, double probe pair experiments were carried out. The scanning probe is used for near field scanning imaging of the static probe. The experimental results verify the feasibility of the two-probe-to-top measurement scheme.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TH742

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