Assessing strain mapping by electron backscatter diffraction and confocal Raman microscopy using wedge-indented Si

Abstract

The accuracy of electron backscatter diffraction (EBSD) and confocal Raman microscopy (CRM) for small-scale strain mapping are assessed using the multi-axial strain field surrounding a wedge indentation in Si as a test vehicle. The strain field is modeled using finite element analysis (FEA) that is adapted to the near-indentation surface profile measured by atomic force microscopy (AFM). The assessment consists of (1) direct experimental comparisons of strain and deformation and (2) comparisons in which the modeled strain field is used as an intermediate step. Direct experimental methods (1) consist of comparisons of surface elevation and gradient measured by AFM and EBSD and of Raman shifts measured and predicted by CRM and EBSD, respectively. Comparisons that utilize the combined FEA-AFM model (2) consist of predictions of distortion, strain, and rotation for comparison with EBSD measurements and predictions of Raman shift for comparison with CRM measurements. For both EBSD and CRM, convolution of measurements in depth-varying strain fields is considered. The interconnected comparisons suggest that EBSD was able to provide an accurate assessment of the wedge indentation deformation field to within the precision of the measurements, approximately 2 × 10−4 in strain. CRM was similarly precise, but was limited in accuracy to several times this value.

Determination of residual stress distributions in polycrystalline alumina using fluorescence microscopy

“…The non-destructive techniques reviewed, neutron and X-ray diffraction (including that using Synchrotron X-rays), Barkhausen resonance, and ultrasonic methods exhibited a lateral resolution range of 1 µm to 10 mm and an axial penetration range of several µm to 1 cm. At the other extreme, recent work at the near nano-scale [37, 52–58] has demonstrated measurements of stress by confocal Raman microscopy and electron backscatter diffraction (EBSD) with an emphasis on microelectronic materials and structures (as opposed to the micro -scale Raman measurements of Al 2 O 3 above [43–49]), with a lateral resolution range of 10 nm to 2 µm and an axial penetration range of 10 nm to 1.5 µm. Following Rossini et al ., Fig.…”

Review: Coefficients for Stress, Temperature, and Composition Effects in Fluorescence Measurements of Alumina

“…Equation (7) is also useful because it provides the fluorescence energy shift when the orientation of the crystal is known in the sample or laboratory frame, and hence is known. Such an orientation might be known from X-ray diffraction or electron backscatter diffraction [138] measurements or from prior knowledge of the material, e.g., a polycrystal in which the grain orientations, and hence the values, are distributed randomly [43]. Combining Eq.…”

“…However, as shown below, both are small (but not negligible) relative to temperature effects. Raman spectroscopy, electron backscatter diffraction, and X-ray diffraction [138] could all be used on thermally grown oxide films to independently calibrate nonlinear effects.…”

Strain Mapping Using EBSD Cross Correlation and Raman Methods

“…To assess the accuracy of the method, several types of sample have been used: e.g. Si1-xGex deposited epitaxially on Si produces a calculable tetragonal strain state in the SiGe which has been studied to design an EBSD strain standard by Vaudin et al [2]; and indentations in Si produced by both wedge indenters [3], which create primarily a one-dimensional (1-D) strain field, and Vickers indenters [4] which create a twodimensional (2-D) strain field. We report EBSD and Raman strain measurements of the 2-D strain field around an indentation in single crystal Si produced by a conospherical indenter and discuss the good agreement between the two techniques; both techniques are potentially useful in enhancing the reliability of microelectromechanical systems (MEMS).…”

“…The reference describes how Raman data were collected using a custom confocal Raman microscope; the EBSD results were used to predict the Raman shifts at each point in the scan. The Raman work is described in more detail in [3] In the second method of shift correction, the sample is translated parallel to the stage rotation axis until an undeformed (strain-free) region of the sample is under the beam and a scan is collected with the same map geometry. The shifts from this scan are subtracted from the strained scan shifts and the analysis proceeds as before.…”