Application of μ-computed-laminography for the in-situ 3D imaging of the growth of large area SiC crystals

A NEW project, funded by the Germany Science Foundation (DFG)

Title: Analysis of the growth kinetics during high temperature crystal growth of large area SiC using μ-computed-laminography for the in-situ 3D imaging of the growth interface

Project Partners: Prof. Dr. Peter Wellmann, Crystal Growth Lab, WW6, TF, FAU, Erlangen, Germany and Dr. Norman Uhlmann, Fraunhofer Institute, IIS-EZRT, Fürth, Germany

The project proposal addresses the kinetics of the growth of single crystalline silicon carbide at ca. 2200 °C and makes use of in-situ measurement data of the growth interface acquired by 3D computed tomography as well as μ-computed-laminography imaging systems.

Based on the results of the first project phase, the scientific study focuses on growth phenomena during the crystallization of SiC boules with a large diameter. For this purpose, the multi-facetted initial growth as well as subsequent coalescence of the growth islands will be analysed for various crystal seed orientations. The goal of the project is to extend and quantify the growth model of the first project phase that already included basic aspects of the lateral overgrowth of crystal defects as well as the enlargement of the single crystalline area. As preliminary work of the anticipated project tasks, a new PVT growth machine (growth of SiC boules with a diameter of 150 mm and 200 mm) has been installed in the lab.

In order to visualize the growth processes at the growth interface of SiC crystals with a large diameter, the installation of an in-situ μ-computed laminography imaging system is planned. Because of the large crystal diameter, X-rays of an energy of 125 keV and even of 160 keV are completely attenuated in the SiC boule. Therefore, the application of a diagonal X-ray imaging system is necessary. The latter task profits significantly from the results of the first project phase in which the analysis of the imaging through a small size 75 mm SiC boule already accounted for X-ray shadowing artefacts.

Finally, the analysis of the experimental data and the systematic investigation of the related growth phenomena during the crystallization of SiC will be carried out using an electronic data base that considers the FAIR-data-principle (Findable, Accessible, Interoperable, and Re-usable). All process data during crystallization of SiC as well as all in-situ CT imaging results and SiC characterization measurements will be collected in the data base that allows a systematic and partially automated analysis.