Recent Developments in SiC Homoepitaxy Using Dichlorosilane for High Power Devices

Abstract

Thick and high quality 4H-SiC epilayers have been grown in a vertical hot-wall chemical vapor deposition system at a high growth rate on (0001) 8 0 off-axis substrates. We discuss the use of dichlorosilane as the Si-precursor for 4H-SiC epitaxial growth as it provides the most direct decomposition route into SiCl 2 , which is the predominant growth species in chlorinated chemistries. The RMS roughness of the films ranged from 0.5-2.0 nm with very few morphological defects (carrots, triangular defects, etc.) being introduced, while enabling growth rates of 30-100 µm/hr, 5-15 times higher than most conventional growths. A specular surface morphology was attained by limiting the hydrogen etch rate until the system was equilibrated at the desired growth temperature. Site-competition epitaxy was observed over a wide range of C/Si ratios, with doping concentrations as low as 2x10 14 cm -3 being recorded. X-ray rocking curves indicated that the epilayers were of high crystallinity, with linewidths as narrow as 7.8 arcsec being observed, while microwave photoconductive decay (µPCD) measurements indicated that these films had high injection (ambipolar) carrier lifetimes in the range of 2 µs. These films also appeared to be free of polytype inclusions.

Progress in Growth of Thick Epitaxial Layers on 4 Degree Off-Axis 4H SiC Substrates

“…In this work, we report the extension of our epitaxy development effort to produce low doped (<1E15/cm 3 ) epiwafers with thickness of 50-100 um on 3-in 4° off-axis substrates. Thick SiC epitaxy on 8° or 4° off-axis substrates has been reported previously [5,6,7,8,9,10]. However, to our knowledge, only O'Loughlin et.al.…”