Growth and Metrology of Silicon Oxides on Silicon Carbide

摘要

Thermal oxidation of SiC by the afterglow method has opened new pathways of opportunity to address both thin film growth and defects that hinder electronic device development with this important semiconductor material. Oxide growth, with rates up to 700A per hour, on SiC has been demonstrated using this technique over a temperature range from 400℃ to 1100℃ at 1 Torr total pressure. Electrical and physical properties of oxide films grown by conventional means or by the afterglow method were obtained with a novel, non-contact charge-voltage (Q-V) metrology approach. This instrument employs a combination of incremental contact potential difference values obtained in response to applied corona charge generated from air. The slope of the Q-V characteristic within a bias range corresponding to accumulation of the semiconductor provides an effective dielectric permittivity value for the grown film. Effective permittivity values for afterglow oxides grown on SiC approach that of SiO_2 grown on silicon substrates whereas the values for oxides grown on SiC in an atmospheric steam oxidation process are always depressed relative to SiO_2 on silicon, indicating that the latter process always produces low-k oxides. A mechanistic discussion regarding these observed differences between the two oxidation methods is presented along with suggestions for an integrated process and metrology approach to reduce defects in oxide films on SiC.