A New Methodology to Analyze Instabilities in SEM Imaging

Abstract

This paper presents a statistical method to analyze instabilities that can be introduced during imaging in scanning electron microscopy (SEM). The method is based on the correlation of digital images and it can be used at different length scales. It consists of the evaluation of three different approaches with four parameters in total. The methodology is exemplified with a specific case of internal stress measurements where ion milling and SEM imaging are combined with digital image correlation. It is concluded that before these measurements it is important to test the SEM column to ensure the minimization and randomization of the imaging instabilities. The method has been applied onto three different field emission gun SEMs (Philips XL30, Tescan Lyra, FEI Helios 650) that represent three successive generations of SEMs. Important to note that the imaging instability can be quantified and its source can be identified.

Local Stress States and Microstructural Damage Response Associated with Deformation Twins in Hexagonal Close Packed Metals

“…To quantify displacements in the range of nanometers, the precision of measurements at reduced length scales at high magnifications is critical. The accuracy of the measured displacement field from DIC, u x,y depends upon the image pixel size along x and y directions, N x,y and sub-pixel shift resolution parameter k, given by the expression [28,30]:…”

“…Under favorable imaging conditions the value of k achievable from the DIC algorithm is 0.01, which amounts to a precision of 1 × 10 −5 [30,31]. It must be mentioned here that the sub-pixel shift resolution is a major criterion for stress measurement with high spatial resolution.…”

On the 3D reconstruction of diatom frustules: a novel method, applications, and limitations

“…In addition, the presence of nonrandom artifacts (e.g., consequence of the scanning procedure) has to be avoided. Therefore, the use of statistical methods to quantify the measurement and the conditions used are strongly recommended (Mansilla et al 2013(Mansilla et al , 2014. The final step consists on the reconstruction of the surface from the displacement fields obtained by DIC by a mathematical approach that considers the rotation of the object and the change in working distance (Faber et al 2015).…”

Using Digital Image Correlation on SEM Images of Strain Field after Ion Beam Milling for the Residual Stress Measurement of Thin Films

“…It was advised that a continuous smooth secondary function can be optimized by the interpolation of a discrete digital image. The grayscale information was used from an integer pixel to a sub-pixel [7]. Later, in order to solve the six unknown varieties, he illustrated the use of the Newton-Raphson method, which was setting an initial guess value before the iteration method.…”

“…Recently, there is a new method to rebuild the image, which is named bi-cubic spline interpolation. The usage of bi-cubic spline interpolation was found to be more accurate than that of bilinear interpolation [7]. Here, by combining digital image correlation (DIC) techniques and focus ion beam (FIB) [2,3], it is possible to measure the residual stress through the independent procedure of ring core drilling for the resolving depth method without any knowledge of the crystallographic and phase structure of the thin films.…”