Methods of depositing boron and carbon containing films are provided. In some embodiments, methods of depositing B, C films with desirable properties, such as conformality and etch rate, are provided. One or more boron and/or carbon containing precursors can be decomposed on a substrate at a temperature of less than about 400° C. One or more of the boron and carbon containing films can have a thickness of less than about 30 angstroms. Methods of doping a semiconductor substrate are provided. Doping a semiconductor substrate can include depositing a boron and carbon film over the semiconductor substrate by exposing the substrate to a vapor phase boron precursor at a process temperature of about 300° C. to about 450° C., where the boron precursor includes boron, carbon and hydrogen, and annealing the boron and carbon film at a temperature of about 800° C. to about 1200° C.