Homoepitaxial silicon carbide deposition processes via chlorine routes

Donor incorporation in SiC epilayers grown at high growth rate with chloride-based CVD

“…The more efficient silicon atom supply makes new carbon sites available faster and thus the nitrogen incorporation should increase. As previously mentioned, no reaction between chlorine and carbon, either in the gas phase or at the surface, has been found in simulations [32,33]. The increased doping, and thereby increased nitrogen incorporation, at higher Cl/Si ratio should thus be explained by the silicon chemistry.…”

“…The previously found sensitivity of the variation of the C/Si ratio at 1600 1C and at low pressure was attributed to hydrogen removal of the carbon atoms from the surface [15]. Simulation studies of chloride-based SiC CVD show that chlorine mainly reacts with silicon to form SiCl x (x=1, 2 and 3) molecules with the SiCl 2 molecule as a very important gas specie contributing to the growth [32,33]. No reactions between carbon and chlorine species either in the gas phase or at the surface were reported.…”

“…This Cl/Si=3 ratio is the Cl/Si ratio in the molecules trichlorosilane and methyltrichlorosilane, which are used without further HCl addition [3,5]. It is also a reasonable Cl/Si ratio since the SiCl 2 molecule is shown by simulation to be the most important Si specie in the chloride-based CVD [32,33], and a small excess of Cl should let the SiCl 2 formation go smoothly. The previous studies on nitrogen doping for the low growth rate chloride-based processes [23,24] do not discuss the effect of the Cl/Si ratio on the nitrogen incorporation.…”

Acceptor incorporation in SiC epilayers grown at high growth rate with chloride-based CVD

“…The effect the C/Si-ratio has on the Al doping on the C-face material could to some extent be explained by the lower growth pressure (200 mbar) used in this study, but also by the different chemistry in the chloride-based process. Simulation studies of chloride-based SiC CVD show that chlorine atoms mainly reacts with silicon atoms to form SiCl x (x=1, 2, 3) molecules with SiCl 2 as the most important gas specie contributing to the growth [25,26]. No reactions between carbon atoms and chlorine species either in the gas phase or at the surface are reported.…”

“…We have generally used a Cl/Si-ratio of 3; this is the Cl/Si-ratio in the molecules trichlorosilane and methyltrichlorosilane when used without further HCl addition [5,7]. It is also a reasonable Cl/Si-ratio since the SiCl 2 molecule is shown by simulation to be the most important Si-specie in the chloride-based CVD [25,26], and a small excess of Cl should assure that the SiCl 2 specie formation goes smoothly. The Cl/Si-ratio has however been varied in a small range (2oCl/Sio4) by only changing the flow of HCl to study the effect on dopant incorporation.…”