Highly selective dry etching techniques for VFET STI recess are provided. In one aspect, a method for dry etching includes: contacting a wafer including an oxide with at least one etch gas under conditions sufficient to etch the oxide at a rate of less than about 30 Å/min; removing a byproduct of the etch from the wafer using a thermal treatment; and repeating the contacting step followed by the removing step multiple times until a desired recess of the oxide has been achieved. A method of forming a VFET device is also provided.