X-ray Diffraction Residual Stress Measurement at Room Temperature and 77 K in a Microelectronic Multi-layered Single-Crystal Structure Used for Infrared Detection

Multilayer CdHgTe-based infrared detector: 2D/3D microtomography, synchrotron emission and finite element modelling with stress distribution at room temperature and 100 K

“…Whereas the biaxial tensile state of CdHgTe tended to be uniform at low temperature (around 30 MPa according to xx and yy consistent with the values obtained experimentally at 77 K [43] ), silicon was in compression under epoxy ( − 10 a − 20 MPa) and in tension under the solder bumps (8-18 MPa) within a depth of a few microns. Thus, using a polycrystalline behaviour law for indium, heterogeneities can already be seen pixel by pixel when applying thermal fields between the centre and the edge of the detector.…”

“…-Biaxial tension is intensified along xx and yy in the CdHgTe, with values from 30 MPa above the solder bumps to 18 MPa in the intersolder areas; the epoxy shows some values outside the scale presented (grey area: 35 MPa on average for xx and yy ). This is consistent with the experimental stress values obtained in [43] , in which the authors used X-Ray Diffraction (XRD) with a 0.8 mm 2 beam to make some mappings from the centre to the edge of the CdHgTe chip: in particular, the measurements at 77 K showed tension stress values up to about 30 MPa. The results show the great influence of the mechanical properties and the CTE mismatch between each layer of the structure on the stress values.…”

“…In the results presented in Section 3.1 ( Fig. 12 (a)), the yield stress of the CdHgTe was fixed at 30 MPa, a value estimated from literature and the residual stress measurements presented in [43] . Other simulations with a yield stress of 60 MPa were launched ( Fig.…”

Simulation and measurement of residual stress and warpage in a HgCdTe-based infrared detector at 100 K

“…Some XRD stress measurements in HgCdTe have already been published in literature, considering a simple epitaxial layer on a CdZnTe substrate [7,8] and an achieved IR detector [9,10]. For the epitaxy process, biaxial stress values were measured, mainly induced by imperfect lattice match between Hg 1-x Cd x Te and Cd 1-y Zn y Te.…”

“…Considering the IR detector, biaxial stresses (compressive at room temperature and tensile at low temperature) were also highlighted and the corresponding values were in good agreement with the above-mentioned difference in CTE between HgCdTe and silicon. A gradient between the center and the edges of the samples was reported [9], but the origin remains to be clearly identified, even with Finite Element Method (FEM) [10]. The warpage evolution with temperature for such detectors does not seem to have ever been studied before, but numerical simulations have been performed on InSb-based detectors [11,12] without any measurements at low temperature.…”