The characteristics of charge trapping and interface states for low temperature chemical vapor deposition (LTCVD) oxide formed on 4H-SiC as carbon-free gate oxide has been studied. Observation of a large flatband voltage shift indicated the presence of many negative oxide charges in the as-deposited LTCVD oxide. Heat treatment was carried out to improve the quality of the LTCVD oxide in various conditions. Interface state density, flatband voltage, and effective oxide charge were decreased with the heat treatment. The heat treatment also greatly improved charge trapping characteristics against electron injection.