Experimental evaluation of uncertainty in sub-nanometer metrology using transmission electron microscopy due to magnification variation

Abstract

Uncertainties due to the magnification variation in sub-nanometer metrology using transmission electron microscopy (TEM) were experimentally evaluated by comparing the measured values of the (220) lattice spacing of a crystalline Si specimen acquired under various conditions. Interday variation of the magnification, intraday repeatability, rotation of the TEM image, specimen exchange, specimen position, defocusing, magnetic hysteresis of the lenses, projection lens distortion, and measurement errors were considered as the uncertainty components. The obtained results reveal that the major uncertainty components are the interday magnification variation, intraday repeatability involving nonuniformity of the specimen structure, magnetic hysteresis of the intermediate lenses, and projection lens distortion. Among these components, it is expected to be feasible to suppress the interday magnification variation to a negligible level by daily magnification calibration, suggesting that minimizing the uncertainties due to magnetic hysteresis of the intermediate lenses, projection lens distortion, and nonuniformity of the specimen structure will be the key factor for further reducing the uncertainty of sub-nanometer metrology using TEM. Furthermore, we found that magnification calibration using an appropriate reference material (e.g. the lattice fringes of crystalline Si) before every measurement should enables sub-nanometer metrology with a relative uncertainty of 3.2%, even if the specimen is introduced into the TEM system by specimen exchange after magnification calibration.

Bottom-up approach for traceable calibration of tip geometry of stylus profilometer

“…The bottom-up traceability approach has been recently developed by several NMIs [34][35][36] for nanometrology. The key concept of the approach is to apply the crystal lattice constant as an internal ruler for traceable nanometrology.…”

“…The realization of the bottom-up traceability approach has been systematically studied and published elsewhere [34][35][36]39]. Figure 2(b) illustrates the geometry of a line feature including the parameters of line width, corner rounding and sidewall angle, measured by using the bottom-up approach.…”

“…Figure 2(b) illustrates the geometry of a line feature including the parameters of line width, corner rounding and sidewall angle, measured by using the bottom-up approach. Its measurement accuracy reaches sub-nm [34][35][36], thus offering a solid metrological basis for true 3D nanometrology.…”

Development and characterization of nano line width based on the fusion of high-resolution transmission electron microscopy and scanning electron microscopy

“…The accurate measurement of the line width is a crucial task for process development and control as the line feature continues to shrink. The commonly used line width measurement technologies include atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) [3][4][5][6][7][8] . The three-dimensional line width AFM image is the convolution result between the actual surface topography and the tip geometry used during scanning [9][10][11][12] .…”