Incorporation of dopants in epitaxial SiC layers grown with fluorinated CVD chemistry

Abstract

Fluorinated chemistry in chemical vapor deposition (CVD) of silicon carbide (SiC) with SiF4 as Si precursor has been shown to fully eliminate the formation of silicon clusters in the gas phase, making SiF4 an interesting Si precursor. However, before a fluorinated CVD chemistry can be adopted, the effect of fluorine on the dopant incorporation must be understood since dopant incorporation is of paramount importance in semiconductor manufacturing. Here, the authors present dopant incorporation studies for n-type doping with N using N2 and p-type doping with Al using TMAl in fluorinated CVD of homoepitaxial SiC. The precursors used were SiF4 as Si precursor and the source of F together with CH4 as C precursor. The authors find that it is possible to control the doping in SiC epitaxial layers when using a fluorinated CVD chemistry for both n- and p-type materials using the C/Si ratio as in standard SiC CVD. However, large area doping uniformity seems to be a challenge for a fluorinated CVD chemistry, most likely due to the very strong Si–F and Al–F bonds.