Nondestructive defect measurement and surface analysis of 3C-SiC on Si (001) by electron channeling contrast imaging
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1068-C07-08
Nondestructive defect measurement and surface analysis of 3C-SiC on Si (001) by electron channeling contrast imaging Yoosuf N. Picard1, Christopher Locke2, Christopher L. Frewin2, Rachael L. Myers-Ward1, Joshua D. Caldwell1, Karl D. Hobart1, Mark E. Twigg1, and Stephen E. Saddow2 1 Electronics Science and Technology, Naval Research Lab, Code 6812, 4555 Overlook Ave. SW, Washington, DC, 20375 2 Electrical Engineering Dept., University of South Florida, 4202 E. Fowler Ave., Tampa, FL, 33620 ABSTRACT The electron channeling contrast imaging (ECCI) technique was utilized to investigate atomic step morphologies and dislocation densities in 3C-SiC films grown by chemical vapor deposition (CVD) on Si (001) substrates. ECCI in this study was performed inside a commercial scanning electron microscope using an electron backscatter diffraction (EBSD) system equipped with forescatter diode detectors. This approach allowed simultaneous imaging of atomic steps, verified by atomic force microscopy, and dislocations at the film surface. EBSD analysis verified the orientation and monocrystalline quality of the 3C-SiC films. Dislocation densities in 3C-SiC films were measured locally using ECCI, with qualitative verification by x-ray diffraction. Differences in the dislocation density across a 50 mm diameter 3C-SiC film could be attributed to subtle variations during the carbonization process across the substrate surface. INTRODUCTION The cubic silicon carbide polytype, 3C-SiC, offers many advantages for high power and high temperature device applications. However, utilizing 3C-SiC films in devices requires careful control of crystallographic defects and surface morphology. Developing high quality 3CSiC films on commercially viable substrates like Si requires optimizing the many processing parameters for chemical vapor deposition (CVD), such as precursor chemistry, process pressure and temperature, as well as optimizing processing procedures, such as the carbonization and growth steps. Progress in optimizing these multiple parameters would greatly benefit from materials analysis approaches that are fast, nondestructive, and provide useful details regarding both the crystalline and surface quality of variously processed films. Recently, the electron channeling contrast imaging (ECCI) technique was demonstrated in a commercial scanning electron microscope (SEM) using a forescatter geometry [1]. This approach has allowed direct imaging of both dislocations and atomic steps in GaN [1-2] and 4H-SiC [3] without sample preparation or significant alteration of the material surface. ECCI is demonstrated in this study for defect and surface analysis of 3C-SiC films grown by different CVD processes on Si (001) substrates. EXPERIMENT In this study, two heteroepitaxial 3C-SiC films roughly 10 µm thick were grown by CVD on Si(001) substrates and then analyzed by ECCI. Details of the reactor and processing steps used are available in the literature [4]. The substrate surfaces were prepared prior to growth
using the standard RCA clean
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