Methods and apparatuses for selective epitaxial formation of films separately inject reactive species into a CVD chamber. The methods are particularly useful for selective deposition using volatile combinations of precursors and etchants. Formation processes include simultaneous supply of precursors and etchants for selective deposition, or sequential supply for cyclical blanket deposition and selective etching. In either case, precursors and etchants are provided along separate flow paths that intersect in the relatively open reaction space, rather than in more confined upstream locations.